October 2019 CAD/CAM 3D Bioprinting and 3D Printing and Restorative Craniofacial Surgery and CALIFORNIA DENTAL ASSOCIATION Journa 3D Printing

Digital Workflow and Three-Dimensional Manufacturing Processes: New Tools Shaping Clinical Practice Paulo G. Coelho, DDS, PhD Vol 47 N o 9 Want to save more on supplies than you pay in dues?

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departments

625 The Editor/The Wrong Questions

629 Impressions

679 RM Matters/Workers’ Compensation: Your Obligations as an Employer

685 Regulatory Compliance/Practice Transition and Patient Records 690 Tech Trends 629

f e at u r e s 635 Digital Workflow and Three-Dimensional Manufacturing Processes: New Tools Shaping Clinical Practice An introduction to the issue. Paulo G. Coelho, DDS, PhD

639 CAD/CAM — The Future Is Here: Overview of Restorative Digital Footprint This article describes the beginnings of CAD/CAM and covers innovations that allow dentists to be more efficient, more precise and contemporary. Gisele Neiva, DDS, MS, MS

645 Current and Future Applications of 3D Bioprinting in Endodontic Regeneration — A Short Review This manuscript is a brief overview of how 3D bioprinting may be relevant to the future of regenerative endodontics. Cristiane M. França, DDS, MS, PhD; Ashley Sercia, BS; S. Prakash Parthiban, PhD; and Luiz E. Bertassoni, DDS, PhD

653 3D Printing of Dental Restorative Composites and Ceramics — Toward the Next Frontier in Restorative Dentistry This article discuss examples of printed dental resins, composites and ceramics and highlights the applications that will pave the way for the emergence of 3D printing as a mainstream method in restorative dentistry. Luiz E. Bertassoni, DDS, PhD

667 Applications of 3D Printing in Craniofacial Surgery This review article describes the ways that 3D printing technology has been incorporated into several aspects of plastic surgery reconstructions. Maxime M. Wang, BA; Amel Ibrahim, MD, PhD; Lukasz Witek, PhD; Paulo G. Coelho, DDS, PhD; and Roberto L. Flores, MD

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Volume 47, Number 10 JournaCALIFORNIA DENTAL ASSOCIATION October 2019 CDA Classifieds.

Free postings. published by the Editorial Production Manuscript California Kerry K. Carney, DDS, CDE Randi Taylor Submissions Priceless results. Dental Association editor-in-chief senior graphic designer www.editorialmanager. 1201 K St., 14th Floor [email protected] com/jcaldentassoc Sacramento, CA 95814 Upcoming Topics Ruchi K. Sahota, DDS, CDE 800.232.7645 November/General Topics associate editor Letters to the Editor cda.org December/Dental

Student Research www.editorialmanager. Brian K. Shue, DDS, CDE January/Importance com/jcaldentassoc associate editor CDA Officers of Research and Dental R. Del Brunner, DDS Education Subscriptions Gayle Mathe, RDH president Annual subscriptions are [email protected] senior editor Advertising available to association members at a rate of $36. Richard J. Nagy, DDS Paulo G. Coelho, DDS, PhD Sue Gardner To manage your printed guest editor advertising sales president-elect Journal subscription online, [email protected] [email protected] Andrea LaMattina, CDE 916.554.4952 log in to your cda.org account or email Judee Tippett-Whyte, DDS publications manager [email protected] for vice president Permission and assistance. View the [email protected] Kristi Parker Johnson Reprints publication online at senior communications Andrea LaMattina, CDE specialist cda.org/journal. Ariane R. Terlet, DDS publications manager secretary [email protected] Joie R. Harrison [email protected] 916.554.5950 communications and Steven J. Kend, DDS media relations specialist treasurer [email protected] Blake Ellington CDA classifieds work harder to tech trends editor bring you results. Selling a practice Debra S. Finney, MS, DDS, speaker of the house Jack F. Conley, DDS or a piece of equipment? Now you [email protected] editor emeritus

can include photos to help buyers Natasha A. Lee, DDS Robert E. Horseman, DDS immediate past president humorist emeritus see the potential. [email protected] Connect to the CDA community by And if you’re hiring, candidates Management following and sharing on social channels anywhere can apply right from Peter A. DuBois executive director the site. Looking for a job? You can post that, too. And the best part— Carrie E. Gordon @cdadentists chief strategy officer it’s free to all CDA members. Kristine Allington Journal of the California Dental Association (issn 1043–2256) is published monthly by the chief marketing officer California Dental Association, 1201 K St., 14th Floor, Sacramento, CA 95814, 916.554.5950. All of these features are designed to Periodicals postage paid at Sacramento, Calif. Postmaster: Send address changes to Journal of the California Dental Association, 1201 K St., 14th Floor, Sacramento, CA 95814. help you get the results you need, Alicia Malaby communications The California Dental Association holds the copyright for all articles and artwork published faster than ever. Check it out for director herein. The Journal of the California Dental Association is published under the supervision of CDA’s editorial staff. Neither the editorial staff, the editor, nor the association are responsible for yourself at cda.org/classifieds. Cris Weber any expression of opinion or statement of fact, all of which are published solely on the authority creative and ux director of the author whose name is indicated. The association reserves the right to illustrate, reduce, revise or reject any manuscript submitted. Articles are considered for publication on condition that they are contributed solely to the Journal. The association does not assume liability for the content of advertisements, nor do advertisements constitute endorsement or approval of advertised products or services. Copyright 2019 by the California Dental Association. All rights reserved.

624 OCTOBER 2 01 9 Editor CDA JOURNAL, VOL 47, Nº10

The Wrong Questions Kerry K. Carney, DDS, CDE

If they can get you asking the wrong questions, they don’t have to worry about the answers. —Thomas Pynchon (1973) “Nicotine, despite what the cigarette companies say, is not like caffeine. It’s a neurotoxin; it hat quote was at the bottom of an email I received the other changes your brain and your nervous system … “ day. Usually, I do not even read the bon mots that, like a family motto, some folks feel compelled Tto share in their messages. However, talk about tobacco harm reduction and not The event promotes itself as a forum this one made me stop and think. nicotine addiction? Maybe it was a typo. for global public health debate. According Everywhere I look, important issues The next line in the email stated in to the website, the GFN is “unique among are being obscured by misdirection. In bold type: “For the first time in 120 years, conferences on nicotine and smoking, politics, promotions of logical fallacies we could eliminate the death and disease we ensure that consumer and consumer are part of the standard playbook. caused by the cigarette rolling machine.” advocacy organisations participate as But that tactic is becoming more and The implication is that darn machine well as manufacturers.” Their program more evident in the advertising and is the public health problem. If we just honors Michael Russell, who may have press releases about e-cigarettes. promoted alternative nicotine delivery been the first to articulate the “tobacco Editors receive frequent “pitches” systems, we could thwart the dangerous harm reduction” ideology. GFN reiterates from publicists. This summer, a public “cigarette rolling machine.” One might his tenet that, “Smoking tobacco is the relations firm contacted me with wonder, if that machine is as dangerous most harmful way of using nicotine. It the following email subject line: as a forum presenter claimed, then in is the tars and gases in cigarette smoke Global conf. aims to eliminate death accordance with the tobacco industry’s that are harmful to health. Many people from smoking through safer nicotine delivery “tobacco harm reduction initiative,” find it hard to stop smoking because It was stunning. In a dozen words, it would pull the plug on those bad they find it hard to go without nicotine. the public health issue of cigarette machines. Why would tobacco companies Making available lower-risk products smoking and its causal relationship with continue to promote cigarettes and helps people to switch from smoking sickness and death was confounded smoking on a global scale if they are and avoid the associated risks. This is with the idea that the whole problem dedicated to tobacco harm reduction? known as ‘tobacco harm reduction.’”1 is that darn cigarette. The spin is: (Or maybe I have it all wrong. Maybe The whole idea of “harm reduction” That smoldering cancer stick is the cigarette rolling machine is so works to the advantage of the tobacco the issue. If we all get behind an dangerous because it actually crushes industry in that it “disentangles the alternative nicotine delivery system that consumers. No, that can’t be right). I notion that (substance) use equals circumvents the cigarette, then “Bob’s guess the question being asked is: How harm and instead identifies the negative your uncle” — everything will be fine, can we get rid of dangerous cigarettes consequences of (substance) use as there is no public health problem. and still enjoy nicotine? But is that really the target for intervention rather The pitch went on to say: “Last week’s the question we should be asking? than (substance) use itself.”2 This is Global Forum on Nicotine in Warsaw, Then something dangerous happened. how tobacco companies can support Poland, brought together 600 delegates from I was alone with my computer and I alternative nicotine delivery systems 70 countries — experts and advocates in was bored. So I started googling the while they “simultaneously work tobacco and nicotine science and policy — Global Forum on Nicotine (GFN). to promote cigarette smoking and to discuss tobacco harm reduction on the What I found out about the convention undermine tobacco control globally.”3 theme ‘It’s time to talk about nicotine.’” and accompanying tech show (read: A little foray into the tobacco harm This forum does not sound too bad. It vendors’ marketplace) allowed me reduction discussion on the web was like a sounds very “sciency,” right? But are they to understand the misdirection and little stroll with Alice through Wonderland. asking the right question? Why is it time to newspeak that was being pitched. There were a lot of “discussions” and

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CDA JOURNAL, VOL 47, Nº10

many questions that, if followed, could brain and your nervous system … And it’s delivery systems’ effects on our clean lead the reader down one rabbit hole after very well established that the younger kids air and its secondary effect on us. another. To paraphrase Thomas Pynchon: are when they start using nicotine, the more When Alice confronts the hookah- If the tobacco industry and the makers of heavily addicted they get, the longer they smoking caterpillar in Wonderland, alternative nicotine delivery systems can use and the harder time they have quitting.”4 she had been reduced to 3 inches in get you asking the wrong questions, they Or maybe a right question is, what is height. She tries to ask him how to don’t have to worry about the answers. the role of alternative nicotine delivery grow back to her normal height again. Maybe we should be thinking a systems in cardiovascular disease? Their conversation is a study in wrong little more about the questions that Or maybe we should be asking, what questions and misdirected answers. we want answered. is the connection between alternative Alice’s confusion may have been the One right question might be, what are nicotine delivery systems and pulmonary result of the secondary smoke of the the ramifications of nicotine addiction? function or noncancer lung disease risk? caterpillar’s hookah. However, in According to Dr. Stanton Glanz, a There exists evidence “that bystanders the end, as the caterpillar gut-slides University of California, San Francisco, absorb nicotine when people around away, he indicates he was sitting on professor and nationally recognized expert them use e-cigarettes at levels comparable the answer to the right question, the on the tobacco industry, “Nicotine, despite with exposure to conventional cigarette important question, all along: One side what the cigarette companies say, is not like secondhand smoke.”5 So maybe we should of his mushroom will make her larger caffeine. It’s a neurotoxin; it changes your be asking about alternative nicotine and the other will make her small. To get meaningful answers, we must make sure we are asking the right questions. n

references 1. Seventh Global Forum on Nicotine. gfn.net.co/faq. 2. Hawk M, Coulter RW, Egan JE, et al. Harm reduction principles for healthcare settings. Harm Reduct J 2017;14:70. doi.org/10.1186/s12954-017-0196-4. 3. Elias J, Ling PM. Invisible smoke: Third-party endorsement and the resurrection of heat-not-burn tobacco products. Tob Control 27(Suppl 1):tobaccocontrol-2018-054433. doi: 10.1136/tobaccocontrol-2018-054433. tobaccocontrol.bmj. com/content/27/Suppl_1/s96. 4. Talesnik D. E-Cigarettes: Are Advocates Just Blowing Smoke? nihrecord.nih.gov/sites/recordNIH/files/pdf/2015/NIH- Record-2015-07-17.pdf. 5. Glantz SA, Bareham DW. E-cigarettes: Use, effects on smoking, risks and policy implications. Annu Rev Public Health 2018 Apr 1;39:215-235. doi: 10.1146/annurev- publhealth-040617-013757. Epub 2018 Jan 11.

CORRECTIONS In the August 2019 issue’s article by Newton et al., the MCDAS as depicted in the figure on page 524 was incorrectly referenced to Wong et al. The correct citation is Howard KE, Freeman R. Reliability and validity of a faces version of the Modified Child Dental Anxiety Scale. Int J Paediatr Dent 2007; 17:281–288. The abstract on page 579 of the September 2019 issue had an error. The X-ray exposure recommendations were last revised in 2012 not 2018.

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TOGETHER WE ARE LIMITLESS Impressions CDA JOURNAL, VOL 47, Nº10

Discovery Could Allow for Root Regeneration

Researchers are increasingly looking to understand epigenetics, the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself, to learn how the body changes over time. This scientific endeavor extends to teeth as well. Yang Chai, DDS, PhD, associate dean of research at Dedicated expertise. the Herman Ostrow School of Dentistry of USC, and colleagues discovered that epigenetic regulation can Insights, tools and resources from control tooth root patterning and development. Their Practice Support experts to help study was published in the research magazine eLife in July. “This is an aspect that doesn’t involve change in the DNA you navigate the business side of sequence, but it’s basically through the control where you dentistry. Just a few of the limitless make the genes available or unavailable for transcription, which can determine the pattern,” Dr. Chai said. member benefits at cda.org. A protein called EZH2 helps the bones of the face to develop, but it was not known how the protein affects tooth root development, according to the study. So the researchers examined what happens when EZH2 is not present in the molar teeth of developing mice. They found that EZH2 and another protein called ARID1A must be in balance to establish the tooth root CDA. THIS IS pattern and the proper integration of roots with the jaw bones. “I feel excited about this because, through human evolution, there have been changes in our diet and environment that can influence our epigenome — the ways our genes are regulated WHERE STRONG — and you can clearly see a difference between the root formation of our dentition versus Neanderthals,” said Dr. Chai. He explained that Neanderthal molars have longer root trunks MEETS SMART. than the ones seen in anatomically modern humans and show late splitting of the roots. This could be due to the effect of diet and exercise on the proteins that turn the genes on and off. The balance of regulators also has a hand in disease and wellness. In different types of cancer, research has shown that the balance of two opposing epigenetic regulators is important. Knocking out one regulator can create cancer, Dr. Chai said, but modulating its opposing regulator can stop the cancer. “These epigenetic regulators, which are not changing the DNA sequences, are important in themselves, but the level of their activity is also important,” he said. “Basically, you can’t have too much or too little — if the balance is off ® track, then you get developmental problems or disease.” The ultimate goal of Dr. Chai’s research on the regulation of tooth development is to regrow teeth. But TOGETHER generating an entire tooth is challenging because of the amount of time it takes for nature to build a tooth from WE ARE development to eruption. So he aims to find ways to LIMITLESS regenerate a molar root … and put a crown on top. Learn more about this study in eLife (2019); doi.org/10.7554/eLife.46426. n

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Treatment with a nanoparticle and hydrogen peroxide (right panel) left little in the way of bacteria (in blue) or the sticky biofilm matrix (in red). Perio Treatment Plus aPDT Lowers Glucose Levels (Credit: Koo Laboratory/University of Pennsylvania) Researchers from China found that patients with diabetes and chronic Antibiofilm Mechanism periodontitis had improved glycemic levels when their periodontal disease was treated with (SRP) plus antimicrobial photodynamic in Nanoparticles Breaks therapy (aPDT) and the antibiotic doxycycline, according to a meta-analysis Apart Dental Plaque published in BMC Oral Health. The researchers wanted to determine which periodontal treatment best In a study published recently in Nature controlled glycemic levels in patients diagnosed with Type 2 diabetes and chronic Communications, researchers from the periodontitis, so they searched medical and scientific databases for randomized University of Pennsylvania used FDA- controlled trials through May 2018 and included 14 trials in their analysis. approved nanoparticles to effectively The trials involved 629 patients with both periodontitis and Type 2 diabetes disrupt biofilms and prevent tooth decay in both an experimental human-plaque-like who had severe gum disease treated with scaling and root planing. The patients biofilm and in an animal model that mimics had no other systemic diseases. The patients had Type 2 diabetes for between four early childhood caries. The nanoparticles and almost 12 years, and their treatments primarily included diet and insulin break apart dental plaque through a unique supplementation or oral antidiabetic medications. The baseline of hemoglobin A1c pH-activated antibiofilm mechanism. levels in the patients varied between 6.2 to 10.4. “It displays an intriguing enzyme-like The use of SRP with photodynamic therapy and doxycycline improved property whereby the catalytic activity is levels of hemoglobin A1c, an indicator of how well diabetes is being dramatically enhanced at acidic pH but is controlled, better than SRP alone or SRP with antibiotics, according to the ‘switched off’ at neutral pH conditions,” research. The treatment combination was most effective for patients who didn’t said Hyun (Michel) Koo, DDS, MS, smoke or had severe Type 2 diabetes complications. PhD, professor in the UP School of While longer-term, well-executed, multicenter trials are needed to corroborate Dental Medicine. “The nanoparticles the results, the findings of the meta-analysis seemed to support that SRP with act as a peroxidase, activating hydrogen photodynamic therapy plus the use of doxycycline had the peroxide, a commonly used antiseptic, best efficacy in lowering glycemic levels. to generate free radicals that potently Read more of this study in BMC Oral Health (2019); dismantle and kill biofilms in pathological doi.org/10.1186/s12903-019-0829-y. acidic conditions but not at physiological pH, thus providing a targeted effect.” Because the caries-causing plaque is highly acidic, the new therapy is able to precisely target areas of the teeth harboring ferumoxytol and other nanoparticles tooth’s surface. That offered very strong pathogenic biofilms without harming the used for medical applications would evidence that this could work in vivo.” surrounding oral tissues or microbiota. render them catalytically inert, Dr. Koo Further studies in a rodent model The particular iron-containing and colleagues demonstrated that they that closely mirrored the stages of caries nanoparticle used in the experiments, maintained peroxidase-like activity, development in humans showed that ferumoxytol, is already FDA-approved to activating hydrogen peroxide. twice-a-day rinses of ferumoxytol and treat iron deficiency, which is a promising “We used plaque samples from hydrogen peroxide greatly reduced the indication that a topical application of caries-active subjects to reconstruct severity of caries on all of the surfaces of the same nanoparticle, used at a several these highly pathogenic biofilms on real the teeth and also completely blocked hundredfold lower concentration, would also human tooth enamel,” said Dr. Koo. “This the formation of cavities in the enamel. be safe for human use, according to the study. simulation showed that our treatment Read more about this study in Though some scientists have not only disrupts the biofilm but also Nature Communications (2019); doi.org/ questioned whether coatings used on prevents mineral destruction of the 10.1038/s41467-018-05342-x.

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Study Finds Oral Health Care Gaps Among Older Minorities Regular visits with the can be Researchers found that visits to the a challenge for older Americans and, as a dentist drop significantly after adults recent study highlights, it can be even more turn 80 due to barriers such as a lack of difficult for minorities and immigrants. access to quality dental care and dental Researchers at NYU Rory Meyers College insurance coverage. These roadblocks of Nursing and the University of Hawai‘i to dental care increase for racial and and language barriers in health care at M¯anoa led the study, which was ethnic minorities and immigrants, who settings, according to the study. published recently in Research on Aging. may experience racial discrimination Unlike previous studies that only looked at recent trends of dental care among adults in the U.S., this study focused on middle-aged and older adults across an extended Stem-Cell Mechanism Could Offer New Solution period of time. Researchers studied how often U.S. adults, 51 years and to Tooth Repair older, saw the dentist as they aged. Stem cells hold the key for tissue engineering, as they develop into Seventy percent of adults had visited specialized cell types throughout the body, including in teeth. Along those a dentist in the past two years, but this rate lines, an international team of researchers, including scientists from the decreased significantly beginning around Biotechnology Center of the TU Dresden (BIOTEC), has found a new age 80. While the frequency in visits mechanism that could offer a potential new solution to tooth repair. decreased with age, researchers found The study was published in the journal Nature Communications in August. the rates of decline for white adults were The research team, led by Bing Hu, DDS, MD, PhD, of the Peninsula slower than black and Hispanic adults. Dental School of the University of Plymouth, U.K., discovered a new “Our study went beyond prior population of mesenchymal stromal cells in a continuously growing mouse research by confirming that racial and incisor model and have shown that these cells contribute to the formation of ethnic disparities were substantial dentin. Importantly, the work showed that when these stem cells are and persistent as people became activated, they send signals back to the mother cells of the tissue to control older, regardless of their birthplace the number of cells produced through a molecular gene called Dlk1. and while adjusting for a wide range This study is the first to show that Dlk1 is vital for this process to work. In of factors,” said Bei Wu, PhD, dean’s the same study, the researchers also demonstrated that Dlk1 can enhance professor in global health at NYU Rory stem cell activation and tissue regeneration in a wound-healing model. This Meyers College of Nursing and co- director of the NYU Aging Incubator mechanism could provide an innovative solution for tooth repair, addressing as well as the study’s senior author. problems such as tooth decay, crumbling and trauma treatment. Further Additionally, the study showed that research is needed to validate the results for clinical applications to determine adults born in the U.S. of all races and the appropriate duration and dose of treatment, according to the study. ethnicities were more likely to see a Learn more about this study in Nature Communications (2019); dentist than immigrants. Researchers doi.org/10.1038/s41467-019-11611-0. noted that the gap in care between adults born in the U.S. and immigrants shrunk A group of mesenchymal (green) stem cells migrating as people aged, suggesting that age and in a tooth to further regenerate tissues. (Credit: acculturation may play a role in decreasing Media and Communications/University of Plymouth) oral health disparities over time. Learn more about this study in Research on Aging (2019); doi .org/ 10.1177/0164027519860268.

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Interprofessional Education Poor Oral Health in Childhood Associated With Improves Dental Health Heart Disease, Stroke A study published in the JAMA Network Open in August found that people Participating in interprofessional with oral infections in childhood were more likely to be at risk for heart disease education (IPE) programs can help and stroke later in life. pediatric nurse practitioner students Researchers from the University of Helsinki and Helsinki University Hospital change oral health behaviors and in Finland reviewed oral exams of 755 people who participated in the ongoing prevent dental problems in patients, according to a new study published Cardiovascular Risk in Young Finns Study; the exams took place when the recently in BMC Oral Health. participants were an average age of 8 years old and then again 27 years later. Because few studies exist that evaluate The research team found that the children with all four signs of oral IPEs in the oral health field, researchers infections (bleeding, cavities, fillings or pockets around the teeth) were 95% from the Tufts University School of Dental more likely to develop thickening of the artery walls than those with none. Even Medicine in Boston conducted a pilot study the children who only had one sign of oral infection were 87% more likely to to measure the impact these programs can develop artery damage, according to the study. have on oral health education and to assess The risk of subclinical atherosclerosis associated with oral infections was their potential to assist nurse practitioners in especially substantial in boys, although only the number of sites with increased improving pediatric oral health outcomes. periodontal probing depth and the brushing frequencies differed by sex. Male The study included 16 first-year pediatric participants with all four signs of oral infections in childhood had a 125% nurse practitioners from Northeastern increased risk for high intima-media thickness values 27 years later. University in Boston with a median age of An association between childhood oral infections with cardiovascular 33. Most of the participants were women. disease risk factors, particularly high blood pressure and BMI, was also evident. During the spring term of 2016, these This study suggests that oral infections in childhood students participated in an IPE, an oral are associated with the subclinical carotid health education seminar and a practical atherosclerosis in adulthood, according to the authors. session. Following the program, student Read more of this study in JAMA Network assessments showed that participants Open (2019); doi:10.1001/ improved their overall health knowledge, jamanetworkopen.2019.2523. with 100% of participants answering questions correctly about children’s first dental visits, bacteria causing tooth decay, age of referral and population group risk. Participants also showed significant and other nondental health care providers Supporters of these IPE programs, improvement, during and after the the adequate motivation, confidence and which include the World Health program, in their awareness of oral attitude regarding oral health issues,” Organization, the Institute of habits, examination of teeth, fluoride said Azita Khanbodaghi, DMD, of the Medicine and the American Public intake, dental counsel and baby bottle department of at Health Association, believe they help use. This was accompanied by improved the Tufts University School of Dental practitioners communicate better, confidence in the students’ abilities Medicine, who led the study. “The program improve quality of care, reduce patients’ to identify teeth with cavities, plaque is raising the importance of oral health costs and hospital lengths of stay and and enamel demineralization. Their components in nursing programs and ... cut down on medical mistakes. ability to apply fluoride varnish also nondental professionals, and in a referral Read more about this study in improved, according to the study. system between pediatric nurse practitioners BMC Oral Health (2019); doi.org/ “IPE may provide nurse practitioners with pediatric/general dentists.” 10.1186/s12903-019-0861-y.

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Excessive Computer Use Related to Teens’ Poor Oral Health Too much computer time could put and found that those who spend more teenagers at risk for poor oral health, time on computers are significantly according to a new study published in more likely to neglect their oral health. the U.S. National Library of Medicine “There is growing evidence to National Institutes of Health. Researchers suggest that computer use is linked examined more than 1,500 18-year-olds with a number of health problems for

teenagers. Much of the attention in the past has focused on its relationships Study Finds Long-Term Periodontal Therapy with obesity, smoking, drinking and changes in behavior,” said Nigel Carter, Promotes Healthy Teeth and Gums BDS, OBE, chief executive of the A recent study conducted by researchers in Switzerland found that Oral Health Foundation in the U.K. decades-long periodontal treatment can help prevent tooth loss and tissue Teenagers who spent longer on a damage, in addition to helping patients maintain healthy gums. The study was computer were less likely to brush their published in the Journal of Clinical in July. teeth, floss and visit the dentist, according “The present study shows long-term success of periodontal therapy over to researchers. Their results showed that many years can be achieved in patients attending dental care in a general boys are particularly at risk, as twice- private practice,” said lead author Véronique Müller Campanile, DDS, a daily brushing dropped below 50% for private-practice dentist in Geneva. those with excessive computer use. Researchers looked at data from 100 patients who had been previously Researchers also discovered a link treated for active periodontal therapy at Dr. Müller Campanile’s office. The between excessive computer use and patients had at least two years of maintenance periodontal therapy, including school absences with up to 25% of periodontal probing, reinforcement and plaque removal, and teens more likely to suffer from bleeding gums and almost twice as likely to researchers customized the recall time for each patient. The patients received miss school because of dental pain. periodontal therapy and maintenance at the practice for two to 28 years, and the Further findings revealed an uptick majority of patients had and were current or former smokers. in sugar consumption among teens The reduction in periodontal disease markers was greater for patients with who spent more time on a computer. more frequent visits and who had received maintenance therapy for more years, The amount and frequency of soda and according to the study, leaving researchers to assume there is no link between juices with added sugar and snacking age and periodontal health research. all increased for those with more than Periodontal complications, including recurrent active periodontitis, only three hours of computer time a day. accounted for 16 total lost teeth among patients, according to the study. “There is an urgent need for Periodontal treatment and maintenance therapy also significantly reduced more education — on both the patients’ probing depth and bleeding on probing. consequences of excessive computer “This further corroborates, under real-life conditions in a dental practice, the use and the benefits of maintaining power of regular maintenance care to reduce the incidence of residual pockets,” good oral hygiene. These need to be said Dr. Müller Campanile. communicated to children and families Learn more about this study in the Journal of before it begins to negatively affect their Clinical Periodontology (2019); doi/10.1111/ health and well-being,” said Dr. Carter. jcpe.13165. Read more of this study in the U.S. National Library of Medicine National Institutes of Health (2019); dx.doi.org/10.1002%2Fcre2.183.

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Digital Workflow and Three-Dimensional Manufacturing Processes: New Tools Shaping Clinical Practice

Paulo G. Coelho, DDS, PhD

GUEST EDITOR

Paulo G. Coelho, DDS, “We become what we behold. We digital workflow leading our profession PhD, is the Leonard shape our tools and then our tools to a new era, from diagnostics to full I. Linkow professor of shape us.” — Marshall McLuhan treatment execution. This issue of biomaterials (dentistry), the Journal provides an overview of plastic and reconstructive surgery (medicine) and uring the second decade fundamental and practical aspects of mechanical and aerospace of the 2000s, it is well the digital workflow and displays how engineering (engineering) acknowledged that health- such change allows for the immediate at New York University. related professional practice and near-future impact of 3D printed Conflict of Interest has a multitude of aspects devices in restorative and regenerative Disclosure: None reported. Dthat include scientific, artistic, dentistry as well as in surgical humanistic and economic components. specialties such as oral and maxillofacial Among these professions, dentistry by surgery and craniofacial surgery. far exceeds others when it comes to The first article, by Gisele Neiva, innovation driving new clinical practice. DDS, MS, MS, one of the pioneers of The observation made by Marshall education in the world, McLuhan is likely more impactful in demonstrates how computerized dentistry dentistry than in other health-related has become a multidisciplinary topic professions. Historically, dentistry has that has begun to be more formally become what it beholds, where clinicians taught in U.S. dental schools. This and scientists shape new technology, piece describes the beginnings of CAD/ and this new technology instinctively CAM and walks the reader through shapes the profession’s behavior toward a journey of innovations that allow the well-being of the patients. dentists to be more efficient and precise Novel technology has been a major and how such technology may be drive in clinical dentistry, but what integrated with additive manufacturing we are currently observing worldwide methods, such as 3D printing, to is not only evolution but a disruptive expedite and improve restorative and development of dental practice due to regenerative dental procedures.

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CDA JOURNAL, VOL 47, Nº10

Two articles communicate the of how successful 3D bioprinting of intraoperative 3D printed models to challenges and advances currently tissues and organs is being translated live bioprinting, 3D printing is helping encountered in restorative dental into regenerative dentistry. Through surgeons refine existing treatment composites and ceramics and regenerative careful evaluation of published content approaches, driving innovation in areas endodontics. The article concerning and preliminary laboratory data, Dr. such as tissue engineering and vascularized restorative materials by Luiz E. Bertassoni, França describes the reasons why the use composite facial allotransplantation. DDS, PhD, et al. addresses key points, of 3D bioprinting methods for dental Maxime M. Wang, BA, an MD where subtractive and additive pulp tissue engineering and regenerative candidate, unequivocally points out manufacturing technologies are contrasted endodontics have remained limited but in the article that as surgeons identify in light of important restorative dentistry extremely promising for future patients clinical needs, 3D printing applications features such as geometric constraints for in need and dental practitioners. to plastic and craniofacial reconstruction fabrication and technology compatibility Lastly, the article by a craniofacial will only continue to evolve. as well as some of the important and surgery group led by Roberto L. Flores, Altogether, these articles will provide rapidly evolving economic aspects of MD, describes how craniofacial surgery the Journal readership with the current 3D printing restorative materials. has seen an increased adoption of 3D state of the art as well as informing The article by Cristiane M. França, printing technology in all steps of the how digital workflow and 3D printing DDS, MS, PhD, et al. depicts examples reconstructive process. From sterilizable will shape the future of dentistry. n

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CDA JOURNAL, VOL 47, Nº10

CAD/CAM — The Future Is Here: Overview of Restorative Digital Footprint

Gisele Neiva, DDS, MS, MS

a b s t r ac t Digital technologies have created a permanent imprint in restorative dentistry. It is no longer possible to conceive a restorative practice that is not at least minimally involved with digital processes. Computerized dentistry has become a multidisciplinary topic that begins to be more formally taught in U.S. dental schools. This article describes the beginnings of CAD/ CAM and walks the reader through a journey of innovations that allow dentists to be more efficient, more precise and contemporary.

AUTHOR he digital revolution is here. Digital Beginnings — Chairside Systems Gisele Neiva, DDS, MS, MS, is a clinical professor Finally, digital processes Computer-aided design/computer- and director of the graduate are mainstream in everyday aided manufacturing (CAD/CAM) had restorative dentistry dentistry as they improve its origins in the aircraft and automotive program in the department workflows from the average industry in the 1950s through computer of cariology, restorative clinician to the large practice-based modeling, simulation and the use of sciences and endodontics at T the University of Michigan networks. Digital dentistry is now numerical control technologies to School of Dentistry. She part of the curriculum of the leading integrate design and manufacturing. also has a part-time dental dental schools in the country, and CAD/CAM integration between practice in Ann Arbor new graduates are generating an design and manufacturing allowed where she focuses on unprecedented digital momentum as the computer designers direct control CAD/CAM and digital dentistry technologies they aspire starting their professional over the manufacturing process, which applied to restorative careers in offices that embrace digital ensured a final product that better dentistry. Dr. Neiva has technologies for dental applications. achieved its intended outcome. been involved in clinical The purpose of this article is to CAD/CAM was first mentioned in and laboratory research elucidate the current state of digital dentistry in the 1970s by Francois Duret, for more than 20 years. Conflict of Interest dentistry, provide a background on DDS, DSO, PhD, but early reports were Disclosure: None reported. the several digital processes that primarily experimental. However, there enhance modern dentistry and dive was always a focus on the potential into the most recent innovations in the clinical applications of the technology. field of computerized dentistry, from The first report of clinical application of image acquisition to 3D printing. CAD/CAM in dentistry was in the late

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1970s by Heitlinger and Rodder,1 who described the Duret CAD/CAM system,7 fabricated a stone model by using a milling however the system was very complex technique. The model was then used and required a large setup that prevented for fabrication. In the it from making a significant impact in early 1980s, the collaboration between a the market. Around the same time, Swiss prosthodontist, Werner Mörmann, several Japanese universities started FIGURE 1. Primescan (Dentsply Sirona). DDS, and an electrical engineer, Marco to research and develop CAD/CAM Brandestini, PhD,2 at the University systems that eventually made it to the of Zurich in Switzerland led to the first Japanese domestic market.8–12 Other such as 3Shape (3Shape, Copenhagen, commercialized CAD/CAM system for groups of collaborators led by Diane Denmark) and Exocad (Exocad Gmbh, chairside applications. They explored the Rekow, DDS, PhD, of the University Darmstadt, Germany). In 2017, Planmeca direct clinical application of CAD/CAM of Minnesota and Reggie Caudill, PhD, introduced Emerald intraoral camera, with the restoration fabrication approach of the University of Alabama, among PlanCad 6.0 Design Center Software by utilizing a single picture to mill the others, were also developing CAD/ and PlanMill 40s (Planmeca, Helsinki). internal surfaces of an inlay. The first CAD/ CAM systems that became commercially And the latest innovation in chairside CAM prototype was introduced a few years available but did not achieve widespread CAD/CAM systems has recently been later in 1983 at the Granciere Conference use in the American market.13,14 introduced by Dentsply Sirona: the in France.3 A couple of years after that, An increasing number of chairside CEREC Primescan AC (FIGURE 1) with the first CAD/CAM crown was designed, systems have been introduced since intelligent automations incorporated milled and installed in a live demonstration then. The E4D Dentist System (D4D in software version 4.6 (2019). by Dr. Duret and collaborators at the Technologies, Richardson, Texas) Congres Association Dentaire Française in was introduced in 2008. The system Intraoral Scanners (IOS) Paris in 1985.4 The Chairside Economical was composed of an intraoral laser An alternative to chairside systems Restoration of Esthetic Ceramics (aka scanner, a mobile design center with that focuses primarily on data acquisition CEREC) system was introduced shortly DentaLogic software and a milling unit is the intraoral scanner (IOS). Dentists after that by SIEMENS AG, Germany with a dedicated CAM computer. In the who choose not to be involved with (now Dentsply Sirona) allowing meantime, the CEREC system has gone restoration design and manufacturing dentists to fabricate same-day ceramic through constant evolution and newer but still would like to use digital inlay restorations as an alternative versions of the system have progressively workflows may decide to replace analogue treatment to amalgam restorations.5 been introduced with parallel software impressions by digital scans using IOS. Around the same time, the price of and hardware advances such as CEREC A significant number of IOS have been gold had increased and nickel-chromium 2 (1994), CEREC 3 (2000), CEREC 3D introduced since the late 2000s, and alloys had been introduced as a substitute RedCam (2003), CEREC AC BlueCam they have constantly been updated and material, causing a drastic increase in (2009) and CEREC AC Omnicam (2012), improved. The intraoral cameras have reported cases of metal allergies. In an which was the first color intraoral scanner. become more ergonomic and faster in effort to provide an alternative treatment The CS 3500 intraoral scanner image processing, and the use of anti- option for patients with a known was introduced in 2013 as part of reflective powder to reduce glare is no allergy to nickel, Matts Andersson, the Carestream system, which also longer necessary. The scans can be edited DDS, PhD, of Sweden attempted to comprehended in-office design with CS until all necessary data is captured. The fabricate titanium copings by spark Restore software and in-office fabrication data are stitched together seamlessly erosion for fabrication of composite with a CS 3000 milling unit. Even though simply by restarting from a previously veneered restorations, which was the Carestream system had limited recorded area. Once the scan is complete, another milestone in dental CAD/CAM chairside capability, the CS digital files the data can be exported in Standard technology, that led to the introduction could alternatively be uploaded to a Tessellation Language (.stl) format to a of the Procera system by Nobelpharma dental laboratory via CS Connect as model manufacturing facility for model (now Nobel Biocare, Zurich) in 1983.6 they are compatible with a number of production or directly to the dental In 1988, Dr. Duret and collaborators commercial laboratory design programs laboratory for restoration fabrication.

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iTero (Align Technology), 3Shape Trios the most recent technologies available. (3Shape) and Trios Color (3Shape) as This demonstrates that dental CAD/ well as CEREC BlueCam (Software 4.0), CAM is an extremely volatile field CEREC BlueCam (Software 4.2) and and that technology evolves faster CEREC Omnicam (Dentsply Sirona, than the literature can record. Charlotte, N.C.). The impressions FIGURE 2. 3M Mobile True Definition Scanner (3M). were superimposed within each test Components of CAD/CAM Systems impression group, for each patient, Dental CAD/CAM systems Some IOSs have added features such as using CAD software (Geomagic Qualify comprehend three distinct processes: color rendition and spectrophotometer 12, 3D Systems, Rock Hill, S.C.). The data acquisition, CAD and CAM. capability for shade selection. authors concluded that despite significant The data acquisition process entails A few of the latest IOSs include iTero differences, all of the digital impression recording the geometry of the teeth Element 5D (Align Technology, San systems tested were capable of producing and interarch relationship by use of Jose, Calif.), 3Shape Trios 4 (3Shape) quadrant impression with precision that an intraoral optical scanner (either and 3M True Definition Scanner (3M) was clinically acceptable.15 Similarly, by confocal laser scanning or active (FIGURE 2). The 3Shape Trios 4 is the Hack and Patzalt measured the ability wavefront sampling). Alternatively, latest innovation from 3Shape. It has two of six intraoral scanners to accurately this may be accomplished by scanning a new features for caries detection, infrared capture a single molar abutment tooth stone model using a benchtop scanner transillumination and fluorescence, in vitro. The scanners tested included (by projection of a light pattern).18 The in addition to other functions already iTero (Align Technology), 3M True scanner transforms image files into digital present in previous versions of the scanner Definition Scanner (3M), PlanScan data in .stl file format, which can be such as shade selection and fast color (Planmeca), CS 3500 (Carestream), processed by the designing software. image acquisition. It is compatible with 3Shape Trios (3Shape) and CEREC CAD is done by a software that lab processing software such as Dental Omnicam (Dentsply Sirona). A master processes the digital data and generates System CAD Design, Implant Studio typodont model of a single crown a digital prototype of the final contour and 3Shape Ortho software as well as the preparation was scanned with a highly of the restoration. The design of the chairside software 3Shape TRIOS Design accurate industrial benchtop scanner 3D contours of the restoration by the Studio for same-day restorations using a and the digital file was compared CAD software can be represented by a third-party mill. The iTero Element 5D to the digital scans of the intraoral combination of geometric shapes that is the most used scanner for orthodontic scanners using a CAD software program can be translated into equations in a applications and includes unique features (Geomagic Qualify, 3D Systems). process known as “triangulation.” The such as near-infrared caries diagnosis and Precision was measured by superimposing CAD output is also in .stl file format. timeline comparisons of caries progression, the benchtop scanner digital file onto CAM can be done either by subtractive treatment planning of orthodontic aligners the digital files recorded by each scanner milling or the additive 3D method. with Invisalign Outcome Simulator and and evaluated for 3D deviations. The Progress Assessment software. The 3M authors concluded that all scanners CAM Processing Variants True Definition Scanner was the first IOS investigated produced clinically Subtractive milling is a CAM process to offer a mobile scanner that operates acceptable accuracy.16 Several other that generates the restoration by removing solely from a proprietary tablet computer. studies are mostly in agreement that material from a prefabricated block It is also available in a cart version and accuracy and precision are comparable through a computer-generated path on uses 3D-in-motion video technology. among the systems tested, especially a mill or grind with the use of diamond The in vivo accuracy and precision for quadrant impressions. In contrast, or carbide burs. The processing method of digital methods have been evaluated most chairside CAD/CAM systems and depends on how the burs are applied to by several studies. Ender and Mehl intraoral scanners are not as accurate the milling block. In 3-axis machining, compared eight digital impression systems or precise for full-arch digital scans and the burs move in two different axes as the for accuracy and precision including distortions can be easily identified.17 block advances in different speeds preset the 3M True Definition Scanner (3M), Nevertheless, no current studies contrast by the operator. More complex shapes

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FIGURE 3. Galileos Comfort Plus CBCT (Dentsply Sirona). FIGURE 4. SICAT Function (Dentsply Sirona). require either 4-axis or 5-axis milling layer by layer according to the computer Tracker can be merged with CEREC where the burs move in translation as coordinates. This is generally applied for data into SICAT Function (FIGURE 4), well as rotational patterns. The quality of 3D printing of digital models. In the CAM allowing integration of motion data in the restoration does not improve with an process “material extrusion,” the printing CEREC, which enables restoration design increased number of processing axes, but a material is selectively dispensed through a based on realistic mandibular dynamics. more detailed restoration may be obtained. nozzle and cured layer by layer by computer Similarly, Planmeca has the 4D Jaw In addition, milling may be directs. Binder jetting comprehends Motion software that uses CBCT images accomplished either dry or with water selective deposition of a liquid bonding and enables real-time visualization of cooling, depending on the material to be agent onto a reservoir of powder material mandibular movements. The system processed. Dry processing is mainly used that is also cured by layers. Lastly, powder tracks and visualizes jaw movements with for milling zirconia and is accomplished bed fusion is a CAM process that uses the Planmeca ProFace camera feature of by carbide burs. This eliminates the thermal energy to selectively fuse regions Planmeca CBCT. Captured 3D images need for a drying cycle and shortens of a bed of powder material.19–21 In general, are displayed in the Planmeca Romexis the overall processing time for the 3D printing enables manufacturing of imaging software, allowing immediate restoration. Most other chairside CAD/ materials that cannot be milled. With the diagnostics of temporomandibular CAM materials are processed via wet continuous development of functionally disorders, mandibular movement grinding where diamond burs are cooled graded materials, it is expected that 3D analysis and articulator programming with a liquid spray. This avoids heat- printing will become the main CAM as well as preoperative planning and induced damage to the restorations. manufacturing method in the future. postoperative treatment verification. Nevertheless, subtractive milling results Another option to record mandibular in wasted material and not all materials Virtual Articulators and Digital Facebows kinetics has been described by Gutman can be milled. The 3D additive method Even though a virtual articulator is and Keller. GnathTech TMJ Digital can overcome these shortcomings. an integral part of the CEREC system, Recording system consists of a jaw tracking Additive methods are also known digital facebows are not yet mainstream, device and virtual articulator package as “rapid prototyping” or “3D printing.” therefore this function tends to not that can be interfaced with existing There are seven additive methods be used on a regular basis and average dental CAD/CAM systems. It allows the for CAM, but only four are used in values are generally used for digital dentist to record and analyze the real-time medical fields: stereolithography, restoration design. However, jaw tracking trajectory of the lower jaw movement as material extrusion, binder jetting and devices are already available, mainly well as the temporomandibular joint.22 powder bed fusion.15 Stereolithography as an integrated solution to cone beam Alternatively, several systems rely is a CAM method also known as computerized tomography (CBCT). on mechanical facebows and casts that “vat polymerization,” where a tank of Galileos CBCT (Dentsply Sirona) are mounted on articulators and then photocurable liquid resin is light cured (FIGURE 3) and SICAT Jaw Motion scanned on benchtop scanners.23

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AI is also a trend in dental technologies. teeth and alveolar ridge. JDR 1989;68(Sp.):924. 10. Kimura H, Sohmura T, Watanabe T. Three-dimensional Primescan (Dentsply Sirona) (FIGURE 5) shape measurement of teeth by means of high precision laser is the first intraoral camera with AI. It displacement meter. J J Dent Mater 1988;7:552–557. has a “smart pixel sensor” with resolution 11. Kimura H, Kawanaka M, Watanbe T, Takahashi J, An H, Omura K. An approach to dental CAD/CAM (part 1) five times higher than any other intraoral measurement of coronal figure. J J Dent Mater 1988;7:413– camera currently available and “intelligent 418. processing” that filters and compresses the 12. Hikita K, Uchiyama Y. Studies on three-dimensional measurement and restoration of tooth crown form by CAD/ data at once generating 1 million 3D data CAM. J Jpn Prosthodont Soc 1989;33(S82):142. 25 points per second for a precise output. AI 13. Rekow D. Computer-aided design and manufacturing in is definitely going to become mainstream dentistry: A review of the state of the art. J Prosthet Dent 1987 Oct;58(4):512–6. in the CAD/CAM industry going forward. 14. Mehl A, Hickel R. Current state of development and FIGURE 5. CEREC Primescan AC (Dentsply Sirona). Lastly, as CAD/CAM technologies perspectives of machine-based production methods for dental evolve, dental materials for CAD/ restorations. Int J Comput Dent 1999 Jan;2(1):9–35. 15. Ender A, Zimmermann M, Attin T, Mehl A. In vivo precision CAM applications must evolve at a of conventional and digital methods for obtaining quadrant Conclusions and Future Perspectives matching rate. Currently, all chairside dental impressions. Clin Oral Invest 2016 Sep;20(7):1495– This article reviewed the CAD/CAM systems rely on subtractive 504. doi: 10.1007/s00784-015-1641-y. Epub 2015 Nov 7. 16. Hack GD, Patzalt SBM. Evaluation of the Accuracy of background of CAD/CAM dentistry, milling for restoration fabrication. As Six Intraoral Scanning Devices: An in-vitro investigation. ADA described the current status of dental printers become more efficient and able Professional Product Review 2015; vol. 10, issue 4:1–5. technologies and opened the door for to print objects of finer precision, it 17. Ender A, Mehl A. In vitro evaluation of the accuracy of conventional and digital methods of obtaining full-arch dental future advancements in the field. is imperative that printable materials impressions. Quintessence Int 2015 Jan;46(1):9–17. doi: Currently, all intraoral cameras improve in quality, appearance, speed 10.3290/j.qi.a32244. and IOS are only capable of recording of processing and longevity in the oral 18. Ueda Y, Yamaguchi T. History of and current situation regarding dental CAD/CAM systems and future perspectives. what is captured in the field of view environment. 3D printed restorations are Hokkaido J Dent Sci 2017 38 (Special Issue):104–110. of the camera. Future directives may already a reality and should continue to 19. Committee F42 on additive manufacturing technologies. explore the use of ultrasonic waves to evolve in order to match and surpass the www.astm.org/COMMITTEE/F42.htm. 20. Standard terminology for additive manufacturing record margins through tissue, saliva physical and mechanical characteristics technologies. web.mit.edu/2.810/www/files/readings/ 24 and even blood. However, if CAD/ of their milled counterparts for a more AdditiveManufacturingTerminology.pdf. CAM systems do incorporate this economical and sustainable workflow.n 21. Ian G, David R, Brent S. Additive manufacturing technologies: 3D printing, rapid prototyping and direct digital technology, the dentist would still manufacturing. 2nd ed. New York: Springer; 2014. have to manage the soft tissue prior to references 22. Gutman Y, Keller J. Jaw tracking device and methods of 1. Heitlinger P, Rodder F. Verfahren zur Herstellung von analysis of patient’s specific TMJ kinematics. Acta Scientific resin cementation of the restoration. Zahnersaltz, Vorrichtung zer Durchfuhrung des Verfahrens. De Dent Sci 2018 2(10):73–79. Patent no. 25911, 1979. Therefore, unless tissue retraction and 23. Alghazzawi TF. Advancements in CAD/CAM technology: 2. Mörmann WH, Brandestini M. Verfahren zur Herstellung hemostasis can evolve parallel with the Options for practical implementation. J Prosthod Res 2016 medizinischer und zahntechnischer alloplastischer, endo und Apr;60(2):72-84. doi: 10.1016/j.jpor.2016.01.003. Epub implementation of ultrasonic technology, exoprothetisher Passkorper. European patent no. 0 0054 2016 Feb 28. 785, 1985. this would be a less impactful advance. 24. Vollborn T, Harbor D, Pekam FC, Heger S, Marotti J, Reich 3. Passkorper. European patent no. 0 0054 785, 1985. 9. On the other hand, artificial S, et al. Soft tissue preserving computer-aided impressions: A Duret F, et coll. Demonstration pratique de l’empreinte optique, novel concept using ultrasonic 3D scanning. Int J Comput Dent intelligence (AI) is already influencing 9e. Entretiens de Grancière. Paris, 21 Septembre, 1983. 2014; 17 (4):277–96. 4. Duret F, et coll. Realisation d’une couronne par ordinateur. the interaction between people and 25. Busch A. Overview of CEREC Primescan technology. Congres ADF, Paris, 25 Novembre, 1985. technology in several fields. Computerized Cerecdoctors Magazine 2019; Q1:16–19. 5. Mörmann WH. The evolution of the CEREC system. J Am systems can be programmed to “learn” Dent Assoc 2006 Sep;137 Suppl:7S–13S. the author, Gisele Neiva, DDS, MS, MS, can be reached at patterns, identify frequent trends and 6. Miyazaki T, Hotta Y, Kunii J, Kuriyama S, Tamaki Y. A review [email protected]. act systematically in response. The of dental CAD/CAM: Current status and future perspectives from 20 years of experience. Dent Mat J 2009 Jan;28(1):44–56. most trivial example of that is the face 7. Duret F, Blouin JL, Duret B. CAD-CAM in dentistry. J Am Dent recognition feature of smartphones; it Assoc 1988 Nov;117(6):715–20. is perplexing how AI expedites several 8. Aoki H, Fujita T, Nishina T. CAD system and NC construction for the automation of dental laboratory. J Dent Technol smartphone processes, from secure 1986;14:149–1526. hands-free login to money transactions. 9. Tsutsumi S, Fukuda S, Tani Y. 3D image measurements of

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CDA JOURNAL, VOL 47, Nº10

Current and Future Applications of 3D Bioprinting in Endodontic Regeneration — A Short Review

Cristiane M. França, DDS, MS, PhD; Ashley Sercia, BS; S. Prakash Parthiban, PhD; and Luiz E. Bertassoni, DDS, PhD

a b s t r ac t 3D bioprinting has emerged as an exciting tool for regenerative medicine and tissue engineering applications. Several examples of successful 3D bioprinting of tissues and organs have been provided in the literature, including many in regenerative dentistry. Despite significant progress, the use of 3D bioprinting methods for dental pulp tissue engineering and regenerative endodontics has remained limited. Here we offer a brief overview of how 3D bioprinting may be relevant to the future of regenerative endodontics.

AUTHORS

Cristiane M. França, Ashley Sercia, BS, is a S. Prakash Parthiban, Luiz E. Bertassoni, DDS, ental pulp regeneration has DDS, MS, PhD, is a student in the DMD PhD, is a research PhD, is an associate emerged as an exciting method research associate in the program at Oregon Health associate in the division of professor at Oregon Health in clinical dentistry in the past division of biomaterials and & Science University and a biomaterials and & Science University. He biomechanics in the researcher at the Bertassoni biomechanics in the holds appointments at the decade. As such, there is a department of restorative Lab. Her major research department of restorative department of restorative growing need for regenerative dentistry at Oregon Health interests include tissue dentistry at Oregon Health dentistry, the OHSU Center Dtreatments that will advance current & Science University School engineering, biomaterials & Science University School for Regenerative Medicine, endodontic therapies. An estimated of Dentistry. Her research and regenerative dentistry. of Dentistry. His major the department of 22.3 million endodontic procedures are focus has been on the Conflict of Interest interests are hard tissue biomedical engineering and 1 effects of laser therapy in Disclosure: None reported. mineralization, vascular and the Cancer Early Detection performed every year in the U.S., which wound healing of different developmental biology. Advanced Research center represents a large section of the $117 billion tissues and different aspects Conflict of Interest (CEDAR) at the Knight annual expenditure associated with dental of tissue engineering and Disclosure: None reported. Cancer Institute. Dr. care in the U.S.2 Despite their outstanding regenerative medicine, Bertassoni leads a success rates for a wide variety of endodontic including dental pulp, multidisciplinary research vascular and bone group working on various procedures, current endodontic materials regeneration. aspects of biomaterials and largely fail to mimic the composition, Conflict of Interest tissue engineering. physical properties and regenerative Disclosure: None reported. Conflict of Interest capacity of the native pulp, therefore, the Disclosure: None reported. development of regenerative materials and therapies has been a focus of extensive research in the field. Bioactive endodontic cements, such as calcium hydroxide (Ca(OH)2), mineral trioxide aggregate (MTA) and Biodentine are used for various

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Nygaard Östby T. Yamamura Iwaya et al. Several groups Huang and Lin Rosa et al. Demonstrated that Showed that pulpal Case report using Isolation of stem cell from different sources in Proposed a Used a hydrogel blood clot promotes cell differentiation blood clot induction the oral environment as tooth germ, dental change in the term scaffold and stem tissue ingrowth into and ability to to treat immature follicle, salivary gland, apical papilla, revascularization cells to engineer pulpectomized root elaborate hard teeth with necrotic inflamed periapices, exfoliated deciduous to revitalization. dental pulp tissue canals of dogs and tissues depend pulp and apical teeth, periodontal ligament, bone marrow, in full-length root humans. on the matrix periodontitis. The term oral epithelial, gingival-derived and canals in an environment. revascularization periosteum. immunodeficient was used. mice model.

1961 1985 2001 2003 2006 2008 2013 1971 2000 2002 2004 2007 2011 2018

Nygaard Östby Gronthos et al. Gronthos et al. Banchs and Trope Murray et al. Iohara et al. Xuan et al. and Hjortdal Treated vital and Isolated human Characterized Proposed the The American Successful pulp Randomized necrotic human teeth dental pulp stem hDPSCs’ self- first protocol of Association of regeneration of clinical trial using inducing intracanal cells (hDPSCs). renewal capability, revascularization of Endodontics adopts mature dogs’ teeth autologous hDPSC blood clot (n = 47). multilineage immature permanent the term regenerative using autologous to fully regenerate Only vital teeth differentiation teeth using a triple endodontics and pulp stem cells dental pulp in young (28/35) presented and clonogenic antibiotic paste. releases a call for transplantation patients with tooth connective tissue efficiency. action. supplemented with trauma. formation. growth factors.

FIGURE 1. Timeline of advances in the field of regenerative endodontics. clinical procedures where the dental pulp of the dentin-pulp complex were pioneered alone would not be sufficient to induce is injured or indirectly affected.3 However, by Nygaard-Östby in 1961 in an original complete dental pulp regeneration. The despite the known ability of these materials study that investigated the role of blood author pointed out that young teeth with to elicit tertiary dentin formation in vital clots in endodontic therapy.8 Briefly, open apex and necrotic pulps showed young teeth, they are not biodegradable, do periapical tissue bleeding was induced to subsequent apical development after the not contain cell adhesive ligands and have fill the pulp chamber with blood clot in use of this protocol and this could be the poor ability to have their physical properties canine (n = 8) and human teeth (n = 17), most encouraging indication for blood adjusted to address patient/case specific then the cervical part of the canal was clot use in endodontics, paving the way needs, which limit their ability to elicit closed with gutta-percha and Kloroperka for future revascularization procedures. controlled and predictable cell-mediated N-O. After observation periods ranging Ten years later the same group published tissue response. Moreover, in events where from 13 days to 3.5 years, teeth were a series of clinical cases where endodontic inert materials are used to replace the extracted and processed for histological treatment using blood clot induction was entire pulp structure, the tooth vitality examination. It was found that all cases used in vital (n = 35) and necrotic (n = 12) and biological response are completely and were asymptomatic, and microscopically, all mature human teeth. The follow-up permanently depleted, potentially leaving root canals contained viable cells showing period ranged from 3.5 months to three the tooth structure weakened and prone a gradual substitution of the fibrin clot into years before the teeth were extracted for to fracture.4,5 Even though these strategies granulation tissue and finally into fibrous histological evaluation. Again, a significant have proven clinical merit, opportunities connective tissue. However, the extent of variability in the outcomes was observed exist to refine the field of endodontics by newly formed tissue inside the root and and described as fibrous tissue occupying introducing a more regenerative approach.6 pulp chamber, as well as the composition, either the entire or part of the root canal The current American Association varied considerably from case to case, and in 28 out of the 35 teeth from the vital of Endodontists’ Glossary of Endodontic three cases showed dental pulps populated group or no tissue formation in any of Terms defines regenerative endodontics by undesired cells as dense inflammatory the formerly necrotic teeth.9 In 2001, the as “biologically based procedures designed infiltrate.8 In general, the findings were paradigm that necrotic pulp could not be to physiologically replace damaged tooth promising, but the high variability on revascularized using blood clots was broken structures, including dentin and root the results, evidence of root resorption by Iwaya and collaborators.10 After this, an structures, as well as cells of the pulp-dentin and lack of an odontoblast layer close to incremental number of clinical cases using complex.”7 Efforts to induce regeneration the dentin, indicated that the blood clot variations of this technique were reported,

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acid (PLLA) scaffolds differentiated into functional odontoblasts that generated tubular dentin, as determined by tetracycline Projector Laser staining and confocal microscopy when Extrusion Light/Lithography tooth slices were implanted subcutaneously.18 Rosa et al. showed even more substantial regeneration in vivo using full-length root canal models of SHED-encapsulated collagen and PuraMatrix hydrogels.19 More recently, our group developed hydrogels that can be photocrosslinked using standard dental curing lights20 and can be used to biofabricate microconduits in the core of empty root canals, which formed vascular capillary-like structures after seven days from injection Inkjet Laser of human endothelial cells in vitro.21 One of the greatest advantages of hydrogels is FIGURE 2. Bioprinting methods, including inkjet, extrusion, laser and light/lithography bioprinting approaches. their ability to undergo patterning on the microscale using a variety of biofabrication indicating that patients with open apex from deciduous teeth was able to regenerate methods. We have reviewed a wide range teeth could benefit from revascularization dental pulp with the odontoblast layer, of possibilities in a recent paper.16 One procedures. This culminated with the blood vessels and nerves in animal models. of the more exciting developments in publication of an optimized protocol using Subsequently, the authors conducted a hydrogel biofabrication in recent years a triple antibiotic paste in 2004, which has randomized clinical trial in 30 young patients was the development of 3D bioprinting been broadly adopted in current days.11 with tooth trauma providing unequivocal tools. A wide range of applications of 3D Based on the advances in tissue evidence that autologous transplant of bioprinting has been reported in many areas engineering, cell biology and biomaterials,12 human deciduous stem cell sheets expanded of medicine and regenerative engineering in 2007 the American Association of from deciduous teeth and when placed into to date, and we encourage the reader to Endodontics launched a review explaining the traumatized tooth was able to guide refer to a recent review where we cover the the term “regenerative endodontics,” its dental pulp regeneration toward clinical specific uses of bioprinting in regenerative goals and a description of the potential outcomes as increased root length, reduced dentistry.22 3D bioprinting as applicable approaches available at that time to apical foramen the width and clinical to endodontic regeneration, nevertheless, regenerate pulp-like tissue, as follows: root- positivity to sensitivity tests when compared has seen much slower progress. Therefore, canal revascularization, postnatal (adult) to conventional apexification treatment.15 to stimulate thinking and outline recent stem cell therapy, pulp implants, scaffold Interestingly, the use of hydrogel-based advances in this area, we provide a brief implants, three-dimensional cell printing, biomaterials is common to the far majority overview of different 3D bioprinting injectable scaffolds and gene therapy.13 of materials-assisted examples of successful technologies and point toward possible Since 2011, in vivo studies in animal dental pulp regeneration in the literature. applications for these methods in dental models have demonstrated that it is possible Hydrogels consist of highly hydrated pulp regeneration in future years. to regenerate dental pulp in mature teeth polymer networks that can be engineered using autologous hDPSCs transplantation with similar composition and properties to Bioprinting Methods with associated growth factors.14 A series of the tissue of interest and can be synthesized Currently, there is an ever-expanding successful reports demonstrating some level with controllable chemistry that allows for range of bioprinting methods, and it is of dental pulp and dentin regeneration are specific cell attachment and response.16,17 For difficult to pinpoint precisely the categories summarized in FIGURE 1. A seminal study instance, Sakai et al. showed in 2010 that that accommodate all 3D printing modalities by Xuan et al. in 2018 showed that the stem cells from human exfoliated deciduous used for tissue regeneration. Therefore, implantation of autologous dental stem cells teeth (SHED) embedded in poly-L-lactic for simplicity, in the following section we

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2. Insoluble 3. Soluble 4. Alg:Dent dentin proteins dentin proteins bioink + cells + 1. Demineralization soluble molecules

Type I collagen Alginate Growth factor Ca2+ Polysaccharide Cell

5. 3D bioprinting with cell-laden bioink

FIGURE 3. Dentin-derived bioink engineered for regenerative dentistry applications. The bioink is composed of dentin-derived soluble and insoluble molecules and alginate and can be encapsulated with cells from various sources. The bioink composition makes it odontogenic and highly cytocompatible. 3D bioprinting of the cell-laden material is achieved by dispensing the alginate-dentin hybrid hydrogel prepolymer through a coaxial nozzle, which is fed with a solution of calcium alginate. Upon dispensing of the two components, the cell-laden hydrogel prepolymer undergoes gelation in the presence of Ca2+, forming a well-structured cell-laden tissue construct. (Adapted from reference 27.)

describe bioprinting methods that fall dispense the bioink, the print head is Laser-Based Bioprinting under the broad umbrellas of extrusion- usually controlled by a pneumatic-, The demand for high-resolution based systems, laser and light lithography mechanical- or solenoid-based system.23–25 bioprinting paved the way to the and inkjet 3D printing (FIGURE 2). Pressurized air is used in the pneumatic adaptation of laser-based printing from Furthermore, we refer to 3D bioprinting system while the mechanical extrusion other fields of manufacturing to the field as the methods that use cells or cell-laden uses a piston or screw to drive the of cell biology and biomanufacturing.34 biomaterials as the printing inks, whereas dispensing unit. Of these, piston-driven An example of such an adaptation 3D printing of cell-free biomaterials units give good control over the flow is the method called laser-induced is referred to as 3D printing only. of bioink through the nozzle, while the forward transfer (LIFT), which is used screw is good for high-viscosity bioinks. in computer chip fabrication for high- Extrusion-Based Bioprinting Solenoid printers use electrical pulses to resolution patterning of metals. To print Extrusion-based 3D printers dispense manipulate the valve, thereby controlling the material, LIFT uses a laser beam and bioink, typically in the form of a fiber, the flow of bioink through the nozzle.26 a donor ribbon composed of the printable in a continuous process through a print With respect to cells, this method shows material. A transport layer beneath the head in a layer-by-layer manner.23,24 good cell viability in general, however, donor ribbon absorbs and transfers the The components of extrusion-based this has been shown to be dependent laser donor ribbon. This laser energy printers usually include a fluid-dispensing upon shear stresses, nozzle diameter creates a high-pressure bubble in the system for extrusion and an automated and the pressure of the dispensing unit. donor ribbon that transfers the donor robotic system for X-Y-Z positioning Extrusion-based bioprinting is the most material onto a collecting substrate.35 of the material. To print the required ubiquitous method used in bioprinting For bioprinting, the ribbon contains the shape, 3D parameters are first fed into as it can print a variety of bioinks bioink (cells or cell-laden materials) computer-aided design (CAD) software including hydrogels,22,27,28 cell aggregates that gets deposited as droplets onto the to create a file that the printer uses to or spheroids29–31 and decellularized substrate. Thus, by moving the substrate dispense the material in a site-specific matrix components.32 Despite these or laser, the patterning of the material manner. The advantage of this method advantages, this method is limited by can be performed on the collecting is that even medical images like MRI the resolution of its printing, which substrate. For creating 3D structures, and CT scans can be converted. To usually ranges from 100–1,000 µm.33 the same process is repeated in multiple

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layers. One of the remarkable effects Droplet-Based Bioprinting Applications of Bioprinting in of this method is that it can print with Inkjet-based bioprinters create 3D Regenerative Endodontics and Dental a resolution of nearly a single cell per biological structures via drop-by-drop Pulp Tissue Engineering droplet. The lack of a nozzle further adds dispensing of the bioink. Droplet-based Application of 3D bioprinting methods to its advantage as clogging issues seen in bioprinting can be categorized into direct for fabrication of dental pulp-like tissue other methods of printing are negated. ink-jetting, acoustic-droplet-ejection and constructs is difficult. This is primarily Cells are also highly viable (> 95%) and microvalve bioprinting, to name a few.40 due to the challenging morphologies and the method allows precise positioning Inkjet bioprinting typically utilizes cartridge- size of root canals and the complexity of of cells within 5 µm. On the downside, based delivery systems to create conventional pulp tissue in native teeth, which would this method requires a bioink with fast 2D structures. 3D structures can be produced need to be replicated in the lab if one gelation kinetics owing to the high by having the Z-component and printing the intends to fully 3D print the dental pulp resolution of the printer and also a fast- structure one layer at a time. Commercially prior to implantation. Different from moving stage for fabrication. Moreover, available cartridges of inkjet printers can also systemic organs or larger tissue structures printing of large-scale tissue constructs be used for this kind of printing,41 as distinct that have been successfully bioprinted is nearly impossible due to the slow to date, the dental pulp conforms to the printing process and the requirement to semiconical and branched morphologies keep cells viable as the slow, layer-by- of root canals. These range from a few layer deposition process takes place. Different from systemic organs or microns in diameter at the root apex up larger tissue structures that have to a few millimeters in the pulp chamber. Light (Lithography) and Digital Light been successfully bioprinted to Thus, by definition, the dental pulp is a Processing (DLP) Bioprinting small, complex architecture that is difficult Sterolithography and digital light date, the dental pulp conforms to replicate with current 3D bioprinting processing bioprinting methods use a to the semiconical and branched systems given their limited resolution. solid freeform technique employing morphologies of root canals. Moreover, and of greater significance, the photosensitive monomer blends as the ability of bioprinting a pulp-like tissue scaffold material.36 The monomer ink would depend on the ability of the printing is poured onto a reservoir tray and is system to replicate the multilayered irradiated either from the bottom or bioinks can be loaded onto separate cartridges structure of the pulp tissue when analyzed from the top with either ultraviolet to create computer-controlled structures. from the pulp-dentin interface toward or blue light. This allows irradiation However, the shear stress on the bioinks and the core of the tissue. For instance, the of the photocrosslinkable monomer, cells are considerable and careful optimization pseudopalisade structure of the odontoblast resulting in curing of a thin layer of of the system needs to be done. Based on how layer, which makes its way directly into the material. Further exposure of the the droplets are ejected, inkjet bioprinting the tubules within the dentin tissue, is monomer to light in a layer-by-layer can be further subdivided into continuous, positioned immediately adjacent to the fashion results in the build-up of 3D drop-on-demand and electrodynamic dentin wall. This layer is separated from constructs. This printing method was methods.42 Acoustic bioprinting uses a the highly cellularized core of the pulp originally used to fabricate cell-free piezoelectric material to create acoustic tissue by the so-called cell-free zone. Next, structures,37 but after the availability of waves that pull the droplets from the the vasculature is denser in the core of new photocurable polymers, it is widely pool by overcoming the surface tension the tissue and branches out as it increases used in the bioprinting of cell-laden of the liquid. In microvalve bioprinting, in complexity toward the pulp-dentin scaffolds.37 Methacrylated materials electromechanical valves are used to create interface.43 Each of these structures are highly suitable for this method as droplets. Resolution of 50–100 µm can be measures approximately 50–100 µm or less, they allow cell-friendly visible light reached from droplet-based bioprinting, which fall below the current resolution as a curing source.38 This method however, clogging issues and a narrow range range of most available bioprinters, can produce 3D structures with a Z of viscosities end up limiting the usefulness especially the more widespread extrusion- resolution down to 10 µm and X-Y to of an inkjet bioprinter for the fabrication based systems. Nevertheless, current a nominal resolution of ~40 µm.39 of clinically meaningful tissue constructs. improvements in printing resolution may

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Core vessels and nerve fibers Microvasculature/ innervation Cell-free zone

Odontoblast-rich zone High-throughput microgel printing Translational Fundamental science DLP bioprinter Microgel injection (i.e., tooth slice) intracanal

FIGURE 4A. Direct bioprinting of cell-laden hydrogels. FIGURE 4B. Bioprinting of injectable microgels.

Micro CT image 3D printing of Injection and culture Engineered Engineered pulp root canal mold of cells/hydrogel pulp implantation intracanal

FIGURE 4C. 3D printing of root canal bioreactors.

FIGURES 4. Current and future examples of possible applications of bioprinting in regenerative endodontics. Cell-laden hydrogels may be bioprinted to directly fabricate pulp-like tissues in the lab (A). Bioprinting of cell-laden or cell-free hydrogels can also form injectable scaffolds that can be easily loaded into the root canal space B( ). Another variation of 3D printing as applicable to regenerative endodontics is the fabrication of root canal-shaped bioreactors, which permit the engineering and maturation of pulp-like tissues in the lab prior to implantation directly into the root canal or patient (C). make these methods more feasible. In light were able to demonstrate that when these Recent examples of 3D bioprinted of these observations, here we point toward hydrogels were loaded with odontoblast- tissues that are present in the possible future applications of bioprinting like cells in 3D, cells remained viable for craniofacial space have been reported in the field of regenerative endodontics and at least seven days after 3D geometries with outstanding success. For instance, highlight relevant examples that may pave were fabricated and cell differentiation in 2018 Murphy et al. reported on the the way for the increased use in the field. was stimulated by the presence of the fabrication of fully 3D printed cartilage, dentin-derived molecules (FIGURE 3). bone and muscle, all using cell-laden Direct Bioprinting of Cell-Laden The application of these fiber-based hydrogels that were dispensed using an Hydrogels cell-laden biomaterials for fabrication extrusion-based bioprinting method.44 Despite the significant limitations of of pulp-like tissue constructs for Similar to the previous description fabricating small and complexly shaped clinical utilization remains distant. proposed for dental pulp bioprinting, tissues using an extrusion-based system that However, the ability of patterning these hydrogels were dispensed over a has a maximum resolution in the order of tissue structures in a well-defined and sacrificial (degradable) support, which several tens of microns, the use of extrusion controllable manner in vitro enables the allowed the cell-laden hydrogels to be 3D printing systems in regenerative development of intricate model systems patterned with the desirable 3D shape, dentistry has shown encouraging results. that may be utilized to better understand cultured in vitro and implanted to show In a recent report, our group demonstrated physiologic and disease processes with remarkable similarities to the native the development of a dentin-derived greater accuracy than what is currently tissues. Using extrusion-based printing bioink that was fabricated by combining possible. This, perhaps, represents systems, several other examples of 3D an alginate hydrogel prepolymer with the greatest advantage of current printing of blood capillaries and osteo/ demineralized and processed human dentin printing systems and how they may be odontogenic materials have been matrix, which contained a wide range applied for dental pulp regeneration proposed.45–47 These illustrate the rapidly of dentin noncollagenous proteins.27 We in the short term (FIGURE 4A). emerging solutions to fabricate building

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blocks that make up the dental pulp, has the same dimension of the build- the printer how to fabricate the actual and that may inspire the regeneration of layer height, microgels can be fabricated tooth structure, which will effectively entire pulp tissue using 3D printing-based with a single light exposure, which be used as a biocompatible mold made approaches in the future. In fact, a recent allows for the fast fabrication. Given out of a biocompatible polymer. After report by our group on the fabrication that hydrogels can be photocrosslinked fabrication of this 3D mold, a cell-laden of prevascularized root canals used a 3D in as little as three seconds without hydrogel (or microgel) can be injected printing inspired method to engineer affecting cell viability,20 these methods into the 3D printed root canal space blood capillaries across the length of represent an extremely fast process of (FIGURE 4C) and the injected cell-laden a root canal model. In that report, we biofabrication that may be suitable for material can be cultured in vitro for as showed that the steps to form a blood regeneration of the dental pulp in root long as necessary under tissue culture capillary in the tooth21 followed the canals. The fact that these hydrogels conditions. After maturation of the same principles used to 3D print blood do not form a monolith, as traditional pulp-like tissue, the whole construct vessels within hydrogels.45 Overall, these materials that are currently injected can be transplanted into the patient’s methods illustrate how the field is slowly into the root canal space do, allows cells root canal space, with the expectation moving toward more feasible ways of to quickly migrate and infiltrate the site that the patient-design may stimulate enabling dental pulp tissue engineering and stimulate faster regeneration. Of a faster regeneration. Examples of this using 3D bioprinting methods. note, this method allows for improved method remain to be fully developed and cell-homing both when the gels are studied, but preliminary studies in our Bioprinting of Prepatterned and fabricated in the absence of cells or laboratory demonstrate that this feasible. Injectable Microgels when cell-laden hydrogels are used Another interesting approach because diffusion of nutrients and Conclusion that has been developed recently and oxygen to cells is improved, which in In conclusion, while 3D bioprinting appears to address other aspects that turn should enhance the metabolic approaches have not been developed are relevant to pulp regeneration activity of the embedded cells. to their full potential for dental pulp despite the lack of site-specific control regeneration, there are sufficient examples is the bioprinting of micropatterned 3D Printing of Patient-Specific in the literature that point toward their hydrogels or microgels. In this method, Regenerative Bioreactors usefulness in the toolbox of dental pulp which draws inspiration from hydrogel Another possible application of 3D tissue engineers and perhaps dental patterning via other mechanisms of printing to regenerative endodontics clinicians in the future. Much research microfabrication, researchers can use a is the concept of 3D printing patient- remains to be developed to enable DLP bioprinter to fabricate microscale specific bioreactors. In this method, effective 3D bioprinting of pulp-like scaffolds that can be loaded with the core principle of bioprinting may tissues in the lab. Nevertheless, progress different biologics (cells, growth factors, be missed because living cells are not in other areas of biomedical engineering etc.) and that are 3D printed in high- actually printed. However, it may will pave the way for the utilization of 3D throughput in a short period of time represent an enabling methodology to bioprinting in regenerative endodontics (FIGURE 4B).48 Because DLP 3D printing achieve improved biological outcomes. and dental pulp tissue engineering with allows for fabrication of cell-laden In such methods, the traditional steps the same success that they have found in hydrogels that are as small as 150 µm of bioprinting tissues are followed other areas of regenerative medicine. n in width and length, and theoretically with small modifications. For instance, acknowledgments as little as 25 µm in height, these the root canals can be imaged using This project was supported by funding from the National microgels can be injected directly into advanced radiology methods (µCT, Institute of Dental and Craniofacial Research (R01DE026170 the root canal space using a regular MRI) to create the digital imaging and 3R01DE026170-03S1 to LEB), American Academy of Implant Dentistry Foundation, Oregon Clinical and syringe needle due to their small size. and communications in medicine Translational Research Institute (OCTRI) — Biomedical As described above, DLP bioprinting (DICOM) files with patient-specific Innovation Program (BIP), IADR-GSK Innovation in Oral works by exposing a layer of the architectural data. The DICOM files Care Awards, Michigan-Pittsburgh-Wyss Resource Center — Regenerative Medicine Resource Center (MPW-RM) and monomer of interest to light only once, would then be used to create the the OHSU Fellowship for Diversity and Inclusion in Research and provided that the set scaffold height computer-aided design that will inform (OHSU-OFDIR to CMF).

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Scand J Dent Res 25;21(6). pii: E685. doi: 10.3390/molecules21060685. 42. Gudapati H, Dey M, Ozbolat I. A comprehensive 1971;79(5):333–349. 26. Bammesberger S, Kartmann S, Tanguy L, Liang D, Mutschler review on droplet-based bioprinting: Past, present and future. 10. Iwaya SI, Ikawa M, Kubota M. Revascularization of an K, Ernst A, et al. A Low-Cost, Normally Closed, Solenoid Biomaterials 2016 Sep;102:20–42. doi: 10.1016/j. immature permanent tooth with apical periodontitis and sinus Valve for Non-Contact Dispensing in the Sub-µL Range. biomaterials.2016.06.012. Epub 2016 Jun 7. tract. Dent Traumatol 2001 Aug;17(4):185–187. Micromachines 2013 4:9–21. doi:10.3390/mi4010009. 43. França CM, et al. 3D-Imaging of Whole Neuronal and 11. Banchs F, Trope M. Revascularization of immature 27. Athirasala A, Tahayeri A, Thrivikraman G, Franca CM, Vascular Networks of the Human Dental Pulp via CLARITY and permanent teeth with apical periodontitis: New treatment Monteiro N, Tran V, et al. A dentin-derived hydrogel bioink Light Sheet Microscopy. Sci Rep 2019 Jul 26;9(1):10860. doi: protocol? J Endod 2004 Apr;30(4):196–200. for 3D bioprinting of cell laden scaffolds for regenerative 10.1038/s41598-019-47221-5. 12. Langer R, Vacanti JP. Tissue engineering. Science 1993 dentistry. Biofabrication 2018 Jan 10;10(2):024101. doi: 44. Murphy SV, Atala A. 3D bioprinting of tissues and organs. May 14;260(5110):920–926. 10.1088/1758-5090/aa9b4e. Nat Biotechnol 2014 Aug;32(8):773–785. 13. Murray PE, Garcia-Godoy F, Hargreaves KM. Regenerative 28. Bertassoni LE, Cardoso JC, Manoharan V, Cristino AL, 45. Bertassoni LE, Cecconi M, Manoharan V, Nikkhah M, endodontics: A review of current status and a call for action. J Bhise NS, Araujo WA, et al. Direct-write bioprinting of cell- Hjortnaes J, Cristino AL, et al. Hydrogel bioprinted microchannel Endod 2007 Apr;33(4):377–90. Epub 2007 Feb 20. laden methacrylated gelatin hydrogels. Biofabrication 2014 networks for vascularization of tissue engineering constructs. 14. Iohara K, Imabayashi K, Ishizaka R, Watanabe A, Jun;6(2):024105. doi: 10.1088/1758-5082/6/2/024105. Lab Chip 2014 Jul 7;14(13):2202–11. doi: 10.1039/ Nabekura J, Ito M, et al. Complete pulp regeneration after Epub 2014 Apr 3. c4lc00030g. Epub 2014 May 23. pulpectomy by transplantation of CD105+ stem cells with 29. Atala A, Forgacs G. Three-Dimensional Bioprinting in 46. Miller JS, Stevens KR, Yang MT, Baker BM, Nguyen DH, stromal cell-derived factor-1. Tissue Eng Part A 2011;17(15- Regenerative Medicine: Reality, Hype and Future. Stem Cells Cohen DM, et al. Rapid casting of patterned vascular networks 16):1911–1920. Transl Med 2019 Aug;8(8):744–745. doi: 10.1002/sctm.19- for perfusable engineered three-dimensional tissues. Nat Mater 15. Xuan K, Li B, Guo H, Sun W, Kou X, He X, et al. Deciduous 0089. Epub 2019 May 6. 2012 Sep;11(9):768–74. doi: 10.1038/nmat3357. Epub autologous tooth stem cells regenerate dental pulp after 30. Norotte C, Marga FS, Niklason LE, Forgacs G. 2012 Jul 1. implantation into injured teeth. Sci Transl Med 2018 Aug Scaffold-free vascular tissue engineering using bioprinting. 47. Kolesky DB, Truby RL, Gladman AS, Busbee TA, Homan 22;10(455). pii: eaaf3227. doi: 10.1126/scitranslmed. Biomaterials 2009 Oct;30(30):5910–7. doi: 10.1016/j. KA, Lewis JA. 3D bioprinting of vascularized, heterogeneous aaf3227. biomaterials.2009.06.034. Epub 2009 Aug 6. cell-laden tissue constructs. Adv Mater 2014 May 16. Annabi N, Tamayol A, Uquillas JA, Akbari M, Bertassoni 31. Jakab K, Damon B, Neagu A, Kachurin A, Forgacs 21;26(19):3124–30. doi: 10.1002/adma.201305506. LE, Cha C, et al. 25th anniversary article: Rational design and G. Three-dimensional tissue constructs built by bioprinting. Epub 2014 Feb 18. applications of hydrogels in regenerative medicine. Adv Mater Biorheology 2006;43(3,4):509-513. 48. Bertassoni LE. Multi-ink 3D Bioprinting of Cell-laden 2014 Jan8;26(1):85–123. 32. Pati F, Jang J, Ha DH, Won Kim S, Rhie JW, Shim JH, et al. Hydrogels and CaP Bone Scaffolds. J Dent Res 2018;97(Spec 17. Xia T, Liu W, Yang L. A review of gradient stiffness hydrogels Printing three-dimensional tissue analogues with decellularized Iss B):1688. used in tissue engineering and regenerative medicine. J Biomed extracellular matrix bioink. Nat Commun 2014;5:3935. Mater Res A 2017 Jun;105(6):1799–1812. doi: 10.1002/ 33. Duan B, Hockaday LA, Kang KH, Butcher JT. 3D Bioprinting the corresponding author, Luiz E. Bertassoni, DDS, PhD, jbm.a.36034. Epub 2017 Apr 3. of heterogeneous aortic valve conduits with alginate/gelatin can be reached at [email protected].

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3D Printing of Restorative Dental Composites and Ceramics — The Next Frontier in Restorative Dentistry

Luiz E. Bertassoni, DDS, PhD

a b s t r ac t While 3D printing of materials for nonrestorative use has become a common finding in dentistry, chairside printing of restorative materials is still in its nascent years. Here we discuss the characteristics that make 3D printing an advantageous fabrication method for restorative dentistry. We discuss examples of printed dental resins, composites and ceramics and highlight the applications that will pave the way for the emergence of 3D printing as a mainstream method in restorative dentistry.

AUTHOR

Luiz E. Bertassoni, DDS, he field of 3D printing has A significant percentage of the PhD, is an associate expanded at an extraordinary common knowledge that has dominated professor at Oregon Health speed and has established itself this area can be attributed to the boom & Science University. He holds appointments at the as a mainstream technology that 3D printing technologies have seen department of restorative in virtually every field in in the popular media, most significantly dentistry, the OHSU Tthe past decade.1 From 3D printed after the expiration of several patents Center for Regenerative shoes2 to entire buildings, houses3 and that protected the intellectual property Medicine, the department human organs,4,5 one could argue that associated with 3D printing back in of biomedical engineering 7 and the Cancer Early virtually anything is “printable” since the early 2000s. With such a rapid Detection Advanced the inception of 3D printing in day- expansion and the free-flowing volume of Research center (CEDAR) at to-day life. Dentistry has benefited information in the unspecialized media, the Knight Cancer Institute. tremendously from this new wave of much of the hype that has been geared Dr. Bertassoni leads a technology6 because manual fabrication toward the potential utilization of 3D multidisciplinary research group working on various of materials in 3D is part of the daily printing in the medical and dental fields aspects of biomaterials and routine of the dental practitioner, and has been somewhat poorly rationalized tissue engineering. many of the technologies that have been to clinicians and patients. Consequently, Conflict of Interest used in dentistry for a number of years many are left to wonder why 3D printing Disclosure: None reported. (i.e., CAD/CAM) are built on similar has often been referred to as the next fundamental concepts to those that industrial and medical revolution.8 In support the foundations of 3D printing this manuscript, we try to elucidate — that is, 3D design and fabrication. some of the overarching concepts that

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Two-photon polymerization Continuous Selective laser sintering Inkjet printing Fused deposition modeling Direct ink printing liquid interface

FIGURE 1. 3D printing examples of high-complexity structures at (top) various length scales, including (bottom) two-photon polymerization, continuous liquid interface production, selective laser sintering, inkjet printing, fused deposition modeling and direct ink writing. (Adapted from references 23, 69–71.)

make 3D printing such a powerful tool Additive Versus Subtractive: Unique justify the hype the 3D printing in the arsenal of those interested in Advantages of 3D Printing industry has received over the past rapid 3D fabrication of dental materials, The process of a subtractive decade. We also give examples of how prototyping and personalized dental manufacture is built on the these individual characteristics may be care. We give emphasis to the emerging fundamental concept that the starting advantageous, if not transformative, technologies that are either in the process material is constructed as a “blank over subtractive methods in the scope of being implemented in clinical dentistry canvas” of a certain 3D shape that can of clinical restorative dentistry. or will soon be utilized by clinicians in be reduced (subtracted) to a certain the next generation of restorative care. shape and size.12 The best examples Geometrical Constraints We anticipate that, different from what of that in dentistry are the well- In 3D printing, there are virtually has typically been acknowledged by the known and widely utilized methods no limits to the internal geometrical general dental community, chairside 3D of CAD/CAM, where a set of burs constraints of a built part. A 3D material printing of indirect crowns and bridges carve out geometric structures in a may be fabricated with intricate internal utilizing both polymeric, ceramic and polymer/ceramic block, giving rise geometries and arbitrary angles, for composite materials is already possible. to their 3D morphology for a certain instance, as the framework of a dental That is in spite of the uncertainty of the clinical application.13,14 In additive bridge or a crown. This can all be regulatory agencies in regulating this manufacturing, on the other hand, performed based on a rationally designed process and making it widely attainable the part is built incrementally, and architecture to better distribute the to practitioners, which is currently the starting point is a 3D computer- masticatory loads using a higher strength perhaps one of the major bottlenecks aided design that is sent to a robotic framework material, whereas the preventing the widespread use of the system that will construct the part out remainder of the crown/bridge structure technology clinically. Literature in of the raw material that is used as an is impregnated with a tougher polymer. this scope has been expanding at a fast “ink.”1 Regardless of the specific details Using subtractive methods, such as pace,9–11 and we hope that this manuscript of each individual printing method, CAD/CAM technology, such intricate helps to pave the way for the transition which we discuss in more detail in internal framework would be difficult of almost exclusively subtractive (i.e., subsequent sections, there are common to fabricate because there are severe milling) manufacturing processes in characteristics that make the method constraints to the angulations that the restorative dentistry to a more equal of additive manufacturing substantially milling unit can reach in order to create distribution of additive (i.e., 3D advantageous over existing subtractive voids and undercuts. This is perhaps the printing) and subtractive manufacturing methods. In the following section, we biggest difference between printing and technologies in the dental practice. list 10 criteria that in our judgement milling — the fact that one allows for

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internal geometrical complexity with in exposing the photopolymer to one Consequently, the cost associated virtual no limits, whereas milling allows large area or many small areas. This is with material waste that is incurred for virtually none (FIGURE 1). The further discussed in the 3D Printing upon the manufacturer, or the fabrication of lightweight parts15,16 with Methods section below. Dental dentist and patient for that matter, stronger frameworks that better distribute laboratories are currently taking is greatly reduced in 3D printing in working loads is a trend that has been advantage of these characteristics comparison to subtractive processes. used in the construction and aerospace to print hundreds of dental crowns engineering fields for nearly half a century at a time (usually overnight) as Scalability (i.e., think of the metallic skeleton of a opposed to having lab technicians While subtractive systems have plane versus the same plane part built out fabricating them one by one. The been built in a variety of sizes for of a monolithic block: which one would cost per minute of use of a printer various applications, the scalability of be lighter?). Still, these characteristics ultimately is the same, however, 3D printing is unique. For instance, have yet to find an application in clinical the throughput can be increased 3D parts have been fabricated using dentistry. 3D printing may enable these by a few orders of magnitude. photolithography methods down to advanced systems to be integrated to the nanometer scale for a range of clinical and/or laboratorial dentistry. applications,17 such as photonics, semiconductors and others.18 These Cost for Variation With 3D printing it can have been used to make polymer parts In traditional manufacturing, the be argued that there is and even high-toughness ceramic complexity of the part dictates how virtually no difference for coatings on microscale architecture difficult it is to fabricate it. Similarly, systems.19,20 At the same time, 3D the more complex the part, the longer the 3D printer to fabricate printing has been used to fabricate it takes to build it; consequently, the a highly complex part or entire rideable cars21 or concrete cost of frabrication is higher. In short, to 3D print a solid block. houses that are fabricated in a matter complexity has traditionally dictated the of a few days.3 These illustrate cost of a certain part, perhaps more so the scalability of the technology, than the price of the raw materials. This from nanometer scale structures of is especially true for manual processes of Material Waste high complexity to massive scale crown, bridge and denture fabrication Dental materials have a high buildings of desirable functionality. in the lab, where technician hours are cost. Therefore, minimizing waste The additional advantage of this a significant component of the cost. is highly desirable. During a milling particular aspect lies in the fact On the other hand, with 3D printing it process, a significant percentage that there are transferable skills can be argued that there is virtually no of the raw material is wasted.6 For and processes that are being difference for the 3D printer to fabricate instance, a single-unit all-ceramic simultaneously optimized for various a highly complex part or to 3D print a crown starts as an individual block, applications, which may ultimately solid block. This effectively means that and after the milling process is inform the best criteria for fabrication there is little cost difference to a printed done, the ceramic block is reduced of dental parts. For instance, the material, regardless of the complexity to a fraction of its original size. The ranges of viscosity that are optimal of the part being fabricated. For some milled material is not reutilized, for printing certain polymers in the 3D printers (i.e., digital light processing but the cost of the restoration still automotive industry may inform [DLP] printers), it takes the same amount considers the cost of all of the raw similar processes that use polymers to of time to print one layer with 100 parts material that was milled. With 3D 3D print dental materials. In other as it does to print one layer with one printing systems, the material waste is words, this means that all fields, part. That is because DLP printers1 print reduced drastically. That is because, regardless of the scale being studied, one layer at a time by exposing the entire in most cases, the amount of material may assist in the development and build envelope of a printer to a digital needed is only what is required optimization of the technology photomask, and there is no difference to build the part and its supports. for various other applications.

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Robotic Precision While many procedures in dentistry remain labor intensive due to the manual character of the protocols, 3D printers, much like CAD/CAM systems, are 100% reliant on the accuracy of robotic instruments. Not only is the precision of these systems invariably improved in comparison to the traditionally manual dental laboratorial methods, but they are also highly repeatable and reproducible. For instance, the ability of prototyping dental parts, inspecting them in a model without worrying about the time and difficulty of repeating long fabrication steps, could be more conducive to better clinical outcomes. In many instances, it is not uncommon for manual processes to result in lightly FIGURE 2. Self-toughening 3D printed composites, where a soft 3D printed material (black) guides the underperforming results, which end up trajectory of a growing crack through a long path to increase the fracture toughness of a rigid material (blue). leading to improvisation and typically a (Adapted from reference 25.) lower quality service. Thus, the ability of being able to quickly replicate a printed part, making the iterations as printers that are designated to the dental Similar to a regular ink printing in needed and testing it again until the market are either small-scale desktop a home or professional office, once desirable part is achieved, are aspects printers or wheeled machines that are a file is sent to the 3D printing unit, that are feasible with 3D printing comparable in size to a CAD/CAM one can expect to simply click a technology. Moreover, once the desired digital impression/computer system. For button and have the part printed at outcome is achieved, the 3D file is instance, printers such as Formlabs’ entire the end of the process. In fact, recent stored in a software, one click away series, 3D Systems’ NextDent 5100 and developments have even removed from obtaining the exact same part. FabPro 1000, Stratasys’ J700 and J720 the requirement for the 3D CAD These are likely to yield better outcomes Dental and Envisiontec’s VIDA and model to be configured to the specs for patients and clinicians alike. Perfectory series are all desktop units. of the printer of choice because many Therefore, the technology is compatible printing systems are compatible with Portable Technology with other apparatus that are typically 3D impression units that can generate One interesting aspect to note kept chairside in a dental office. a CAD file and submit it directly to with regard to the rapid expansion the printer of choice. This enables of 3D printers is the wide variety of Skill Level easy and near seamless replication of printing systems available in the market. Although 3D printers can require an existing part by simply copying its Interestingly, while several industrial a substantial level of engineering external 3D outline and 3D printing. printers remain rather large, the far and materials expertise, these are Moreover, the familiarity of the dental majority of commercially available off- typically limited to those interested clinician with existing subtractive the-shelf printing systems are desktop in understanding or modifying the processes makes the transition to compatible or sufficiently small to fit in machine itself and much less so for a 3D printing process much more a dental office. In fact, the majority of the ones interested in simply printing. user friendly than in other fields.

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Fabrication Time FabPro 1000 and Envisiontec’s VIDA such that the crack length is increased Printing time is a subject of much and Perfectory series. As such, the substantially, thereby increasing the overall debate in the field of 3D printing and basic principles that guide the field of toughness of a material25 (FIGURE 2). something that may be considered a contemporary restorative dentistry, such This is a strategy that remains poorly significant drawback preventing immediate as free-radical polymerization, share explored in dentistry, but would certainly and widespread implementation of 3D strong similarities to the driving principles be leveraged to produce restorative systems printing technology in the dental office. of many 3D printing methods. This with built-in toughening mechanisms With existing technologies, 3D printing means that materials systems that have that are only possible due to the nature of a high-resolution dental prosthesis can originally been developed for clinical use of the printing process. Again, this is an be time-consuming, and the possibility of and have been extensively characterized advantage of 3D printing that would never doing this chairside as the patient waits are, by and large, compatible with a be possible with subtractive technologies. seems less than ideal at this point. Having range of 3D printing systems. This is In summary, the advantages of 3D said that, simpler provisional restorations especially true for polymeric materials printing technologies are many and the and smaller single-unit crowns can already and light-/laser-assisted 3D printers. potential benefits for dentistry are palpable. be 3D printed in as little as 20 minutes In the following section, we describe recent or less,22 with the advantage that the examples of printed restorative materials, clinician or assistant can be working on inclusive of polymer composites and other aspects of the treatment as the printer While the fabrication of ceramics, which illustrate the potential of fabricates the restoration. Moreover, a a metal-ceramic restoration, 3D printing in the future of dental care. large body of research is being performed for instance, remains far-fetched on newer methods to reduce printing 3D Printing Methods time for fabrication of various materials. at the moment, printing of It is hard to pinpoint exactly how One recent technology was able to reduce multimaterial polymeric parts many types of 3D printing systems are the time required to print a complex and is certainly a reality. available in the market to date. The relatively sizeable 3D structure from more popularity of 3D printing methods makes than three hours to less than 10 minutes;23 the variations of the more common this technology is now commercialized by printing types to be developed with the company Carbon 3D. Technologies Combination of Materials surprising speed nowadays. Add to like this are likely to have a major impact Multimaterial printing is still a nascent that the fact that printing methods are in the implementation of 3D printing area in 3D printing, and it has been mostly often developed exclusively for a type in dentistry. Recent research has also restricted to variations of the same material of material of interest, and very seldom developed innovative methods to 3D print type. For instance, Stratasys commercializes one can find a 3D printer that can print the outer geometries of a part in its entirety a printing system called PolyJet, where various types of materials without some without the need for printing one layer at a many photocrosslinkable monomers can modification. For instance, an extrusion time.24 This is another example that is likely be dispensed simultaneously and in a 3D printer that dispenses plastics, which to be useful for printing of simpler objects coordinated fashion to fabricate parts with is very common, is invariably incapable that can be useful to dental applications. spatially coordinated polymer composition. of performing extrusion of metals or While the fabrication of a metal-ceramic glass26,27 using the same mechanisms of Technology Compatibility restoration, for instance, remains far- dispensing. The same can be said for One advantageous feature of 3D fetched at the moment, printing of 3D printers used for tissue fabrication in printing technology is that a significant multimaterial polymeric parts is certainly a regenerative medicine in comparison to component of the 3D printing market reality. These have been used to fabricate more common thermoplastic materials. devoted to dentistry relies on the polymer parts that have self-toughening So much so that the field of 3D printing concept of light polymerization of mechanisms, for instance, by combining of tissues and organs is more commonly photoactive monomers.22 This is the very soft, rubbery materials and very rigid referred to as 3D bioprinting,4,5 and in case for systems such as Formlabs’ entire photopolymers and guiding the trajectory fact it must account for a series of highly series, 3D Systems’ NextDent 5100 and of cracks through the soft component complex biological parameters that can

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be easily ignored when printing with coordinates the motion of the tri-axial Another common type of 3D printer plastics, metals or ceramics. That is stage/robot and dispense speed of the that uses light polymerization is the because printing of living cells is far more printed ink. It is this coordinated motion digital light processing (DLP) 3D printer difficult and specific than printing with of these axes with the dispense rate of the (i.e., EnvisionTEC’s Perfactory/Vida/ inert plastic materials, for obvious reasons. ink that allows a material to be printed EnvisionOne, Autodesk’s Ember, etc.). Despite the specificity of each individual in 3D in a spatially controlled manner. In this process, printing is obtained by printing system described above, one can creating a sequence of digital photomasks generally classify 3D printers under three Light/Laser Polymerization using a computer software for each layer broad categories: extrusion, light/laser Different from extrusion 3D printers, of a printed part. A common projector polymerization and inkjet. There are a light and laser polymerization-based 3D shines the light against the bottom multitude of subtypes to these categories printers (FIGURE 3B) do not necessarily surface of a monomer vat and the entire that fall beyond the scope of this review, rely on the X-Y motion of a dispensing layer is photocrosslinked at the same but generally speaking, 3D printers will robot or the coordinated Z-movement of time in the areas predefined by the fall under one of these categories. a print head or a build platform. Instead, digital photomask. As the build platform moves up, a new layer of prepolymer is Extrusion 3D Printing added underneath the cured part and In extrusion 3D printing (FIGURE 3A), the final product is built incrementally typically a thermoplastic polymer, shear- There are a multitude of one layer at a time. There is certainly a thinning material — either polymeric subtypes to these categories range of advantages and disadvantages or not — or a material of adjustable that fall beyond the scope of to each type, and we encourage the viscosity is loaded to a container that is reader to refer to review papers on these connected to a print head.28,29 Depending this review, but generally topics to determine the best use for on the mode of polymerization or the speaking, 3D printers will fall each application.34,37 It is interesting to characteristics of the material, the print under one of these categories. note, however, that DLP 3D printers head has to be specific to the mode of (and variations thereof) have become delivery of the material. For instance, a more common choice for printing of extrusion of a thermoplastic polymer restorative dental materials, which are the happens via heating of the print head to in light and laser polymerization-based focus of this article, including polymers a certain temperature; upon dispensing 3D printers, a photocurable monomer and ceramics, and it appears that DLP of the molten material, the quick drop in is dispensed onto a vat and either the printers may have some advantages for temperature solidifies the printed ink.30 vat itself moves down while a top-down these classes of materials22 given their This is the common mode of action of light/laser raster shines on the surface rapidly expanding popularity. Noteworthy more traditional extrusion desktop 3D of the monomer or a build platform aspects include the greater speed of printers, also referred to as fused deposition moves up as a bottom-up projected light fabrication of multiple parts and resolution modeling (FDM) 3D printers, which photocrosslinks the material.34–36 This of DLP versus laser-rastering printers. currently dominate the commercial market process repeats itself for each layer of a worldwide. In a different example, when 3D structure, thus giving rise to a 3D Inkjet 3D Printing using a preceramic paste, for instance, part. The more common types of 3D In comparison to extrusion and temperature control may not be as critical printers that fall under this category are lithography 3D printing, inkjet 3D because the viscosity of the material or stereolithography printers, where a laser printing (FIGURE 3C) has received its “shear-thinning” capacity becomes the light controlled by a digital mirror travels less attention with regard to its more important parameter that needs to on the bottom surface of the monomer potential application for restorative be regulated such that the material can be vat while a build platform travels up, treatments. In inkjet printing, the squeezed through a needle.28,31–33 Regardless allowing another layer of monomer same requirements for the integration of the print head mechanism, extrusion to seep under the photopolymerized of X-Y-Z robots that were described 3D printers are mounted on some form material, thus resulting in the layer- in extrusion printing also exist — of X-Y-Z robot, and a computer software by-layer construction of a 3D part. meaning, a dispensing robot needs

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Projector Laser

FIGURE 3A. Extrusion. FIGURE 3B. Light/lithography. FIGURE 3C. Inkjet. FIGURES 3. Schematic drawing of mechanism of action. to dispense the monomer ink in X applications, it is not hard to imagine market, the streamlining of the full digital and Y while either the build platform situations where a multimaterial operation process in the dental clinic has or the dispenser itself moves in the dental restoration would be printed remained less than desirable because the alternate direction to allow for the using a system like this if the majority of digital scanners do not yet incremental layer build-up.36,38 One correct monomers are tuned to be communicate seamlessly with 3D printers; key difference, of course, is that compatible with the PolyJet system. similarly, dental restorative “inks” are the ink must be of a substantially At this stage, it appears that this not as broadly compatible with various lower viscosity to permit “jetting” of falls beyond the commercial scope of 3D printers as conventional restoratives droplets of the material.39–41 This has the manufacturers of the PolyJet. are, comparatively, “compatible” the potential to make inkjet printing with any clinician. Secondly, another far more accurate because literally 3D Printed Restoratives — Polymers important reason that explains the slow one drop of material at a time can be and Composites implementation is the fact that dental deposited onto a desired substrate. As mentioned at the beginning of materials for restorative applications The disadvantage of that, on the other this article, although 3D printing has have fallen under somewhat complex hand, is that printing time can be expanded at a tremendous pace as of late regulatory hurdles by the FDA and other increased quite drastically, thus making and dentistry has been one the fields that regulatory bodies worldwide.43–45 Materials the overall printing time quite slow in has more substantially benefited from used intraorally (either 3D printed or comparison to other printing methods. the technology, it appears as though the not) must undergo regulation as a class II One key advantage of inkjet standard perception of most clinicians is device that requires a series of biological systems is that these have been that 3D printing of restoratives is not yet testing methods, and it remains unclear far more advanced in their ability clinically feasible, despite recent efforts how the FDA regulates the process of of printing multiple monomers at to review potential applications.11 This is printing differently from the final printed the same time (i.e., multimaterial despite the fact that commercial printers product (i.e., restorative inks and 3D printing). This is probably due to and printing manufacturers that heavily printers themselves). In other words, there the level of advancement that the target the clinical dentistry market have is little variability in the manufacture technology of inkjet printing has been available for a number of years (i.e., of a commercial composite material, accumulated over many years from EnvisionTEC, Stratasys, 3D Systems, however, a 3D printable composite ink home office printers. Stratasys, one DWS, Formlabs, NextDent and several can have far different outcomes depending of the larger manufacturers of 3D others). Perhaps this is due to the fact that on the type of printer that is used and printers worldwide, holds the patent printing of restoratives remains far more the printing parameters that are set up for a system called PolyJet.42 The complex and difficult to attain than other in the machine, as we and others have PolyJet printer works by dispensing dental products, such as dental models, demonstrated recently.22,46–48 How one multiple photocrosslinkable monomers mouthguards, orthodontic appliances may regulate these discrepancies remains of potentially various mechanical and so on. Similarly, the knowledge a topic of debate,43 and it appears that properties and colors at the same time. required to confidently implement that this has halted the implementation of 3D Although these materials have yet in a dental practice remains quite specific printing in dentistry to a certain extent. to cross the boundaries of simplified at this stage. Moreover, despite the fact Despite these limitations, 3D printing monomers that have relatively poor that the 3D printing industry has been of polymeric restoratives has been mechanical performance for clinical introduced into the clinical dental accomplished with relative success in

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the past few years, and that goes beyond the more widespread printing of surgery guides, models, orthodontic appliances and so on, which in this author’s opinion are not as critical to the restorative dentist. Readers are encouraged to refer to a recent FIGURE 4A. Bridge. FIGURE 4B. Crown. review paper that describes some basic FIGURES 4. Examples of 3D printed dental composites. (Adapted from references 22 and 72.) principles and opportunities of 3D printing of polymeric materials for dentistry.37 On the commercial side, although various the manufacturers’ websites, the printed and, according to the company’s website, companies have contributed significantly E-Dent 400 can reach a flexural strength is approved for long-term provisional to the introduction of 3D printing in of approximately 107 MPa, while a restorations in Europe. It is also worth clinical dentistry (i.e., Stratasys, 3D conventional Filtek P60 (3M ESPE) noting that despite the fact that these Systems, Formlabs, DWS, Autodesk and composite reaches approximately 160 commercially available resins are many others), EnvisionTEC arguably has MPa and a Z100 reaches about 130 MPa. technically only approved for long-term established a leadership position on the Of interest, the material can also be (up to one year) provisional crown and manufacture of 3D printers for restorative stained with standard composite staining bridge applications, their composition dental applications in the U.S. The kits that allow for blending with other and chemistries are very similar to a company currently has at least four 3D shades of restorations and natural teeth. variety of composite resins currently printers that are compatible and engineered Another interesting development available in the dental market. Although for printing of restorative dental materials, on the commercial end of printable the specifics of their composition are including the Envision One cDLM Dental, resins for restorative dentistry is the not disclosed due to patent protection, Vida HD, Vida HD Crown and Bridge establishment of manufacturers that, these materials are essentially composed and the more advanced Perfactory P4K for a long time, were exclusively of dimethacrylate monomer mixtures series. These printers are capable of a focused on the commercialization of with ~50% w/v of inorganic filler in the printing resolution of up to ~25 µm in X, printable monomers without necessarily range of 0.04–0.7 µm in size, which are Y and Z and can reach printing speeds commercializing a 3D printer itself. This essentially similar compounds to those of up to 80 mm/hour, depending on the is the case of the European company used in traditional restorative . For instance, at maximum speed, NextDent, which currently has a portfolio materials already clinically available. according to manufacturer information, of 30 biocompatible resins for dental Despite the commercial use of these a printer would be capable of printing six applications, out of which two were materials in the dental market, myriad orthodontic arch models in less than 15 developed for provisional crowns and aspects remain largely unknown in minutes (Envision One cDLM Dental). bridges and one for printed dentures, the scope of 3D printing of restorative Of greater relevance to the context that are indirect restorative materials dental materials, which also justifies of this article, as with a number of that the clinician can use as opposed their slow introduction into the other 3D printing companies (DWS, to printable materials that are mostly market. Research in this space has also 3D systems and others), EnvisionTEC marketed to lab technicians. As of been slower than desirable, and only currently commercializes a composite recent, NextDent has entered the 3D recently research groups have begun to resin material called E-Dent 400 MFH, printing market and now commercializes address the intricacies of the printing which is a microhybrid resin printing the NextDent 5100 system, which is process that are likely to determine material that is biocompatible according manufactured in partnership with 3D the usefulness of printed materials in to a Class IIa determination by the FDA Systems, one of the larger companies the dental practice. The following and is approved for 3D printing of crowns in the field of 3D printing. Similar to section describes some of the research and bridges. The material can also be EnvisionTEC, NextDent’s crown and that our group and others have done used for the 3D printing of veneers that bridge resin (NextDent C&B MFH) is to elucidate some of the important have a reasonable surface finish as well also a microfilled hybrid material that aspects influencing the properties of 3D as denture try-ins. For comparison, per reaches a flexural strength of ~107 MPa printed dental restorative materials.

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One of the first set of research studies design.22 Using these parameters, there need to be created. Moreover, the finish and addressing the influence of the printing was no significant influence of number polish quality of the printed material will method on the performance of 3D printed of layers on the mechanical properties increase proportionally with the number resins was the study by the Wismeijer Lab of the printed part, different to what of layers that are printed. Similarly, what is at the Academic Center for Dentistry Alharbi et al. reported. Moreover, 3D the influence of printing orientation in the in Amsterdam.10,46–48 To the best of our printed samples had comparable peak clinical performance of a printed bridge or knowledge, the first publication from stress to Integrity and were significantly crown over the years? Does it matter if a this group in the area of 3D printing of stronger than Jet, which is a gold standard crown is printed at 0 degrees or 90 degrees? indirect restorative materials for clinical material for clinical use. On the degree One recent publication suggests that these intraoral use came out in 2016. The of conversion, 3D printed samples also parameters matter quite significantly.47 investigators studied the effects of build appeared to have higher and more How much exactly they matter depending direction on the mechanical properties homogenous polymerization than both on the type of printing (inkjet, extrusion of 3D printed complete-coverage interim Integrity or Jet. These results underline or lithography) remains to be determined. dental restorations.48 The authors the potential of 3D printed materials to Also, are there postprinting processes showed that a 3D printed interim dental that are better to prevent delamination of material (Temporalis, DWS) had higher printed layers or to improve mechanical compressive strength when printed in a performance? Is the chemistry of current 90-degree orientation than when printed Does it matter if a crown dental resins, such as photoinitiators in a 0-degree orientation. The authors is printed at 0 degrees or and other monomer molecules, optimal proposed that the compression of the 90 degrees? One recent for printing systems as much as they are sample led to microcracks that expanded for chairside photopolymerization using from main cracks formed between publication suggests that the conventional dental curing light? individual printed layers. This is in line these parameters matter These are questions that are relevant to with previous reports that the mechanical quite significantly. be addressed if the field of 3D printing properties of printed materials that are in dentistry intends to expand and anisotropic in nature can be influenced play a role in the clinical setting like by the printing orientation25 and that CAD/CAM systems currently do. the adhesion between successive layers match (and even surpass) the properties An additional thought worth keeping is weaker than the adhesion within the (mechanics and degree of conversion) of in mind is that current methods of 3D same layer.12 In a follow-up paper, our conventionally cured restorative dental printing and much of the investment that group compared the effects of a variety of materials. Examples of these 3D printed has been put forth in the field have been printing parameters that are preset in a composites are shown in FIGURES 4. geared toward processes and methods low-cost, commercially available desktop Overall, these comparisons and research that are lab-technician friendly and very 3D printer (Formlabs+) when used in papers highlight some of the fundamental little in comparison has been targeted to combination with an unfilled provisional questions that come up when delving the clinician or 3D printing of intraoral resin (NextDent C&B). We then deeper into the complexities of 3D printing restorative materials. From a clinical compared the mechanical performance of intraoral restorative materials. Many standpoint, one may argue that it is more and degree of conversion obtained aspects of the printing process and how it valuable for the dental practitioner to using the 3D printed material versus may influence clinical performance remain have a chairside 3D printer that can that obtained with standard temporary unknown. For instance, what are the precise address the aspects of the practice that are crown and bridge materials such as effects (beyond the mechanical ones) when currently done manually (i.e., 3D printed Integrity and Jet. Our results showed that the clinician chooses to print a crown using restoratives) than 3D printers that can samples printed at a 90-degree printing incremental layers of 10 µm as opposed handle laboratorial work (i.e., models, orientation relative to the build platform to 100 µm? This is especially difficult working and study casts, mouthguards and using a preset determined for a considering that a printed dental crown (or and so on). In short, very little of the “3D white resin color resulted in the higher any part) will take longer to be produced printing revolution” has directly reached printing accuracy relative to the CAD depending on the number of layers that the practice of intraoral restorative dentistry.

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TABLE 1 Ceramic 3D Printers and Specifications (Adapted from reference 60.) 3D printer Technology Build volume (mm) Price (US$ or €) Country of production 3D Systems ProX DMP 200 Powder 140 x 140 x 100 > $250K United States Dental 3d-figo FFD 150H FFF/FDM 150 x 150 x 120 $50K–$100K Germany 3DCeram Ceramaker Resin 300 x 300 x 110 > $250K France Admatec ADMAFLEX 130 Resin 96 x 54 x 120 €125,000 Netherlands AIM3D ExAM 255 FFF/FDM 255 x 255 x 255 $50K–$100K Germany DDM Systems LAMP Resin — > $250K United States ExOne Innovent Jetting 160 x 65 x 65 $100K–$250K Germany HP Jet Fusion 3D 4210 Jetting 406 x 305 x 406 $100K–$250K United States Kwambio Ceramo One Jetting 350 x 350 x 380 $25K Ukraine/United States Lithoz CeraFab 7500 Resin 76 x 43 x 150 > $250K Austria nScrypt 3Dn 450HP FFF/FDM — > $250K United States Prodways ProMaker V6000 Resin 120 x 500 x 150 > $250K France Voxeljet VX4000 Jetting 4000 x 2000 x 1000 > $250K Germany XJet Carmel 1400 Jetting 500 x 280 x 200 > $250K Israel

Another aspect that is imperative for discrepancies between the general in desirable load-bearing mechanical widespread use of 3D printing in restorative perception and existing market in 3D properties for intraoral dental use. In order dentistry is that 3D digital impression systems printing of dental polymers because for preceramic materials to be extrudable need to be engineered to communicate printing of ceramic materials is not as or printable using traditional 3D printing better with existing 3D printers to allow common and widespread as printing of methods, they need to have a relatively for a seamless interface between these polymer plastics for the general public. The low viscosity (or be shear thinning) and complementary modalities of digital dentistry. latter have been highly accessible to the include a variety of binders and other Technically, this is already possible because nonspecialized community for many years additives to permit fine-tuning of the there are digital impression devices that allow now and effective printing of high-density presetting properties that make the material one to save and export STL files that are ceramics with potential for intraoral moldable or extrudable. Early work from readable in 3D printers.49,50 Different from clinical application is in its nascent years.51 Lewis et al.57,58 paved the way for more CAD/CAM systems that have gone above Having said that, 3D printing of ceramic substantial contributions on 3D printing and beyond in the integration of scanning structures has been used in dentistry for of ceramic materials, which more recently and building, 3D printers have remained regeneration of bone tissue for a number have been reported by Smay et al.59 These stagnated in their individual niches. More of years, and the reader is encouraged groups, however, focused primarily on the frequently than not, manufacturers either to refer to other recent reports by our “direct writing,” or extrusion 3D printing, focus on the 3D printing machine, the resin group for an update on that field.5,52–55 of colloidal ceramic materials that solidify or some combination thereof, and virtually Despite the use of a variety of 3D to reach higher properties upon sintering, no company has yet come up with a seamless printing techniques to fabricate ceramic- and it was not until the establishment interface between digital scanner, 3D printing based scaffold materials for craniofacial of far more advanced ceramic printing system and a set of printable resins, especially regeneration, printing of dental ceramics technologies that printing of high-density for intraoral use in the restorative realm. for restorative applications has received and high-strength dental ceramics began little attention and most of the published to take form. TABLE 1 summarizes recent 3D Printed Restoratives — Ceramics works date back to only a few years ago.56 developments in the 3D printing industry Perhaps even more than printing of This is because printing of ceramics has that are applied to ceramic printing, dental composites, 3D printing of dental traditionally been done with the use which are also illustrated in FIGURE 5. ceramics for intraoral use has commonly of preceramic pastes or slurries, which And although only a fraction of these been seen as a distant reality. This is generally cannot reach the level of density systems are compatible with high-strength perhaps more understandable than the that usual dental ceramics have to result dental ceramics 3D printing, the summary

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FIGURE 5. Sintered ceramic parts 3D printed using the standard stereolithography or lithography-based ceramic manufacturing (LCM) techniques. (Adapted from ceramic-monomer mixture undergoes a references 61 and 63.) process of cleaning and debinding, upon which the polymer is removed without affecting the stability of the preceramic structure. Upon sintering, an average 25% of linear shrinkage occurs, and the ceramic particles fuse to result in a high- density (> 90%) ceramic part that can be fabricated at virtually any geometry, with a maximum resolution of about 25 µm. The method is theoretically compatible with any type of ceramic material. The mechanical properties of these parts are excellent and reach flexural strength values that are as high as 430 MPa, which closely approximate the flexural strength of some dental alumina ceramics, for instance.64 This method was originally developed illustrates the breadth of machines and loss and 30% linear shrinkage.61 Still, the at the Vienna University of Technology,65 methods available in the market. mechanical properties of these preceramic and high-density (97%–99%) zirconia and Polymer-derived ceramics,61 a class of monomers are below par in comparison to alumina structures with Vickers hardness of printable ceramics introduced in recent traditional dental ceramic materials. While as high as 17.5 GPa (as rigid as dentin) have years, are photocrosslinkable materials these ceramics are relatively weak in the been produced.66 The LCM technology is that upon heating (typically under inert context of dental restorations, they paved currently owned and commercialized by atmosphere) can pyrolyze into more stable the way for more advanced printing of Lithoz GmbH, a spin-off company from the and rigid ceramic structures. Recent work high-strength ceramics with properties that lab that developed the method, and our team has demonstrated that by attaching thiol, are more adequate for intraoral use, such has done considerable work in collaboration vinyl, acrylate, methacrylate or epoxy as those obtained via a lithography-based with Lithoz to test the mechanics of a groups to an inorganic backbone, such ceramic manufacturing (LCM) method. variety of high-density alumina samples 3D as a siloxane, silazane or carbosilane, In fact, perhaps the most relevant printed by LCM. We have also replicated these preceramic monomers can be introduction into the dental market some of the microarchitectural complexities photocrosslinked with standard UV has been the development of the LCM of dental enamel in the form of printed light and fabricated with highly intricate technology,63 which simply modifies existing ceramics, which we hope will form the basis shapes.62 This allows for straightforward methods of DLP 3D printing to make it for the next generation of “bioinspired” stereolithography printing of preceramic compatible with printing of a high-density dental ceramic crowns and bridges with monomers with virtually any size and a very ceramic slurry mixed with a binder and the same durability, strength and toughness high printing resolution. For instance, a UV- photoactive monomers. Although not as the native dental enamel. Lithoz has curable siloxane resin was formulated with much information is available on the also partnered with large dental ceramics methylsiloxane and vinylmethoxysiloxane precise mechanisms of action of LCM- companies in Europe, and in principle, 3D and 3D printed using a Formlabs Form based 3D printing, the system generally printers that are capable of fabricating high- 1+ 3D printer. Pyrolysis at 1,000 degrees operates as a standard DLP 3D printer resolution, high-density and high-strength Celsius in argon formed fully dense intricate and the key difference is in the material dental ceramics are already available to be ceramic parts, with no porosity or surface composition. The ink is composed of a purchased for clinical/lab use (regulatory cracks observed by scanning electron mixture of ceramic microparticles (~60%) concerns notwithstanding). The feature microscopy and transmission electron in a photocrosslinkable matrix, which resolution generated using LCM has been microscope (TEM). This was, as one sets upon exposure to the projected light. reported to reach 25 μm and several examples would expect, accompanied by 42% mass After printing, the 3D printed “green” of complex structures have been reported,67,68

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TABLE 2 Comparison of 3D Printing Technologies Used for Ceramics Printing (Adapted from reference 66.)

Material Technology Forming Power source Part size Resolution Speed Surface Process type method quality cost Slurry-based Stereolithography Polymerization Laser 100 μm– μm Slow High Medium 100 cm Digital light Laser 100 μm– μm Medium High Medium processing Polymerization 100 cm Two-photon Polymerization Laser 1 μm–1 mm nm–μm Slow High High polymerization Inkjet Binder bonding Thermal energy 100 μm–10 mm mm Slow High Low Direct ink writing Extrusion Thermal energy 100 μm–10 cm μm–mm Medium Low Low Powder-based Extrusion Binder bonding Thermal energy 10 mm–10 cm μm–mm Medium Medium Medium Selective laser Powder fusion Laser 10 mm–10 cm μm–mm Medium Low High sintering Selective laser Powder fusion Laser 10 mm–10 cm μm–mm Medium Low High melting Solid-based FDM Extrusion Thermal energy 100 mm–10 cm mm Medium Low Medium

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Adv Healthc Mater 2018 Manufacturing of Implantable 3D-Printed Medical Devices. Clin jeurceramsoc.2018.11.013. Apr;7(8):e1701161. doi: 10.1002/adhm.201701161. Epub Transl Sci 2015 Oct;8(5):594–600. doi: 10.1111/cts.12315. 64. Guazzato M, et al. Strength, fracture toughness and 2017 Dec 28. Epub 2015 Aug 3. microstructure of a selection of all-ceramic materials. Part I. 29. Kyle S, et al. ‘Printability’ of Candidate Biomaterials for 46. Osman RB, Alharbi N, Wismeijer D. Build Angle: Does It Pressable and alumina glass-infiltrated ceramics. Dent Mater 2004 Extrusion Based 3D Printing: State-of-the-Art. Adv Healthc Mater Influence the Accuracy of 3D-Printed Dental Restorations Using Jun;20(5):441–8. 2017 Aug;6(16). doi: 10.1002/adhm.201700264. Epub 2017 Digital Light-Processing Technology? Int J Prosthodont 2017 Mar/ 65. Zanchetta E, et al. Stereolithography of SiOC Ceramic May 30. Apr;30(2):182–188. doi: 10.11607/ijp.5117. Microcomponents. Adv Mater 2016 Jan 13;28(2):370–6. doi: 30. Tan DK, Maniruzzaman M, Nokhodchi A. Advanced 47. Alharbi N, Osman RB, Wismeijer D. Factors Influencing 10.1002/adma.201503470. Epub 2015 Nov 6. Pharmaceutical Applications of Hot-Melt Extrusion Coupled with the Dimensional Accuracy of 3D-Printed Full-Coverage Dental 66. Rongxuan H, Wei L, Ziwei W, et al. Fabrication of complex- Fused Deposition Modelling (FDM) 3D Printing for Personalised Restorations Using Stereolithography Technology. Int J Prosthodont shaped zirconia ceramic parts via a DLP-stereolithography-based Drug Delivery. Pharmaceutics 2018 Oct 24;10(4). pii: E203. doi: 2016 Sep-Oct;29(5):503–10. doi: 10.11607/ijp.4835. 3D printing method. Ceram Int 2018. 44 (3): p. 3412–3416. doi. 10.3390/pharmaceutics10040203. 48. Alharbi N, Osman R. Wismeijer D. Effects of build direction on org/10.1016/j.ceramint.2017.11.135. 31. Rider P, et al. Additive Manufacturing for Guided Bone the mechanical properties of 3D-printed complete coverage interim 67. Felzmann R, et al. Lithography-Based Additive Manufacturing Regeneration: A Perspective for Alveolar Ridge Augmentation. dental restorations. J Prosthet Dent 2016 Jun;115(6):760–7. doi: of Cellular Ceramic Structures. Adv Eng Mater 2012 Int J Mol Sci 2018 Oct 24;19(11). pii: E3308. doi: 10.3390/ 10.1016/j.prosdent.2015.12.002. Epub 2016 Jan 21. May;14(4):1052–1058. ijms19113308. 49. Lee B, et al. Evaluation of the fit of zirconia copings 68. Schwentenwein M, Homa J. Additive manufacturing of dense 32. Gleadall A, et al. Review of additive manufactured tissue fabricated by direct and indirect digital scanning procedures. J alumina ceramics. Int J Appl Ceram Tec 2015 Sep;12(1):1–7. doi. engineering scaffolds: Relationship between geometry and Prosthet Dent 2018 Aug;120(2):225–231. doi: 10.1016/j. org/10.1111/ijac.12319. performance. Burns Trauma 2018 Jul 3;6:19. doi: 10.1186/ prosdent.2017.08.003. Epub 2018 Feb 7. 69. Kinstlinger IS, et al. Open-Source Selective Laser Sintering s41038-018-0121-4. eCollection 2018. 50. Wesemann C, et al. Accuracy and efficiency of full-arch (OpenSLS) of Nylon and Biocompatible Polycaprolactone. PLoS 33. Jammalamadaka U, Tappa K. Recent Advances in Biomaterials digitalization and 3D printing: A comparison between desktop One 2016 Feb 3;11(2):e0147399. doi: 10.1371/journal. for 3D Printing and Tissue Engineering. J Funct Biomater 2018 Mar model scanners, an intraoral scanner, a CBCT model scan and pone.0147399. eCollection 2016. 1;9(1). pii: E22. doi: 10.3390/jfb9010022. stereolithographic 3D printing. Quintessence Int 2017;48(1):41– 70. Vidimce K, Wang SP, Ragan-Kelley J, Matusik W. OpenFab: A 34. Kotz F, et al. High-Performance Materials for 3D Printing 50. doi: 10.3290/j.qi.a37130. programmable pipeline for multi-material fabrication. ACM Trans in Chemical Synthesis Applications. Adv Mater 2019 51. Barazanchi A, et al. Additive Technology: Update on Current Graph 2013 Sep; 32(136). doi: 10.1145/2461912.2461993. Jun;31(26):e1805982. doi: 10.1002/adma.201805982. Epub Materials and Applications in Dentistry. J Prosthodont 2017 71. Truby RL, Lewis JA. Printing soft matter in three dimensions. 2019 Feb 18. Feb;26(2):156–163. doi: 10.1111/jopr.12510. Epub 2016 Nature 2016 Dec 14;540(7633):371–378. doi: 10.1038/ 35. Taormina G, et al. 3D printing processes for photocurable Sep 23. nature21003. polymeric materials: Technologies, materials and future trends. 52. Annabi N, et al. 25th anniversary article: Rational design and 72. Revilla-Leon M, et al. A review on chemical composition, J Appl Biomater Funct Mater 2018 Jul;16(3):151–160. doi: applications of hydrogels in regenerative medicine. Adv Mater mechanical properties and manufacturing work flow of additively 10.1177/2280800018764770. Epub 2018 Apr 2. 2014 Jan 8;26(1):85–123. manufactured current polymers for interim dental restorations. 36. Marro A, Bandukwala T, Mak W. Three-Dimensional Printing 53. Bertassoni LE. Bioprinting and Microscale Technologies for J Esthet Restor Dent 2019 Jan;31(1):51–57. doi: 10.1111/ and Medical Imaging: A Review of the Methods and Applications. Regenerative Dentistry. J Dent Res 2015 94A:0009. jerd.12438. Epub 2018 Oct 27. Curr Probl Diagn Radiol 2016 Jan–Feb;45(1):2–9. doi: 54. Ferracane JL, Pfeifer CS, Bertassoni LE. Biomaterials for 10.1067/j.cpradiol.2015.07.009. Epub 2015 Jul 21. Oral Health. Dent Clin North Am 2017 Oct;61(4):xi–xii. doi: the author, Luiz E. Bertassoni, DDS, PhD, can be reached at 37. Stansbury JW, Idacavage MJ. 3D printing with polymers: 10.1016/j.cden.2017.07.001. Epub 2017 Jul 29. [email protected]. Challenges among expanding options and opportunities. 55. Thrivikraman G, et al. Biomaterials for Craniofacial Bone Dent Mater 2016 Jan;32(1):54–64. doi: 10.1016/j. Regeneration. Dent Clin North Am 2017 Oct;61(4):835–856. dental.2015.09.018. Epub 2015 Oct 20. doi: 10.1016/j.cden.2017.06.003.

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CDA JOURNAL, VOL 47, Nº10

Applications of 3D Printing in Craniofacial Surgery

Maxime M. Wang, BA; Amel Ibrahim, MD, PhD; Lukasz Witek, PhD; Paulo G. Coelho, DDS, PhD; and Roberto L. Flores, MD

a b s t r ac t Plastic surgery has seen an increased adoption of 3D printing technology in all steps of the reconstructive process. From sterilizable intraoperative 3D printed models to live bioprinting, 3D printing is helping surgeons refine existing treatment approaches, driving innovation in areas such as tissue engineering and vascularized composite allotransplantation. As surgeons identify clinical need, 3D printing applications to plastic and craniofacial reconstruction will only continue to evolve.

AUTHORS

Maxime M. Wang, BA,  Lukasz Witek, PhD, is an Roberto L. Flores, MD, he classic principles of plastic is a medical student at the assistant professor in the is the Joseph McCarthy surgery practice mandate the NYU School of Medicine department of biomaterials associate professor of restoration of form and function and a research fellow at the and biomimetics at the reconstructive plastic Hansjörg Wyss Department NYU College of Dentistry surgery at the Hansjörg by balancing aesthetic and of Plastic Surgery at the in New York. Wyss Department of Plastic physiological demands while NYU Langone Medical Conflict of Interest Surgery and the director Tlimiting morbidity. Plastic surgeons Center in New York. Disclosure: None reported. of the cleft lip and palate routinely operate on all parts of the body, Conflict of Interest program at the NYU with virtually no anatomic barriers, and Disclosure: None reported. Paulo G. Coelho, DDS, Langone Medical Center in PhD,  is the Leonard New York. therefore often collaborate with a broad Amel Ibrahim, MD, I. Linkow professor of Conflict of Interest array of medical, surgical and dental PhD, is the director of the biomaterials (dentistry), Disclosure: None reported. specialists. While each anatomical domain human stem cell research plastic and reconstructive has its own set of considerations, a common program in the department surgery (medicine) and plastic surgery principle is the replacement of biomaterials and mechanical and aerospace biomimetics at the NYU engineering (engineering) of “like with like.” In other words, the use of College of Dentistry, the at New York University. autogenous tissue with similar histologic and Hansjörg Wyss Department Conflict of Interest mechanical properties is often preferable of Plastic Surgery and the Disclosure: None reported. to prosthetic replacement and is a guiding NYU Langone Medical principle to reconstructive and aesthetic Center in New York. She is a member of the Royal surgery. In craniofacial reconstruction, for College of Surgeons. example, autogenous tissue is commonly Conflict of Interest preferable in the restoration of deformities Disclosure: None reported. caused by congenital, oncologic, traumatic and iatrogenic insults. Still, there remain limitations to the gold standard of autogenous reconstruction

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TABLE Types of 3D Printing Primarily Used in Craniofacial Surgery Technique Pros Cons Material Fused deposition modeling (FDM)1,2 No need for secondary support Heat-driven extrusion process. Thermoplastic polymers structure. Limitation of materials. Stereolithography (SLA)3 Complex features can be Only applicable for use with Poly (propylene fumarate) (PPF) incorporated. photo-polymeric resins. Series of post-processing steps to clean uncured resin. Single-material printing. Selective laser sintering (SLS)5,6 Support structure is not required. Requires a high-powered laser to fuse Various powder form materials (nano-HA, Limited post-processing steps particles together. carbonated HA, β-TCP) necessary. Resolution is a function of laser beam. Single-material printing. 3D plotting/direct ink writing Fabrication feasible at room Commonly associated with a sintering Biomolecules (DIW)/robotic assisted deposition/ temperature; capable of bioplotting. step when working with ceramics. Cells robocasting7–9 Higher resolution (50 μm–1,000 μm). Bioactive ceramics (HA, β-TCP) Multiple materials may be printed/ Bioactive glasses codeposited. including size, shape and stock of donor layers composed of liquid, polymer or to photopolymerization-based 3D printing, tissue and increased length of the colloidal gel material to construct the SLS utilizes a high-powered CO2 laser operation as well as donor-site morbidity. final object. Layer dimensions vary to fuse or sinter layers of particles. The These challenges, however, present an based on printing technique, printer laser scans the material — commonly opportunity for innovative approaches to resolution and printing material. ceramics — in a preset pattern, heating craniofacial reconstruction, such as the 3D printing technologies are currently it to its material melting point, resulting application for additive manufacturing or categorized into four platforms (TABLE). in selective sintering in a layer-by- 3D printing. The benefits of 3D printing Fused deposition modeling (FDM):1,2 layer fashion to build the 3D form. technology to the field of plastic surgery FDM is an extrusion-based 3D printing 3D plotting/direct ink writing (DIW)/ include the manufacture of customized system. Objects are printed using a robotic assisted deposition/robocasting:7–9 patient models, surgical templates and thermoplastic polymer dispensed from a DIW-based 3D printing, commonly cutting guides, personalized implants spool through a heated extrusion nozzle referred to as robocasting, utilizes a and tissue engineering scaffolds. and deposited onto a build platform. computer-controlled microprinter Most polymers solidify immediately upon equipped with a syringe gantry. DIW 3D Printing deposition on the build platform. This allows for the assembly of a synthetic 3D printing is the process by method allows for printing in multiple structure, commonly composed of which two-dimensional (2D) forms colors and is commonly used to print ceramic-based material, in a layer- are sequentially deposited or fused in dental models or facial prosthesis patterns. by-layer fashion.10 DIW allows for layer-by-layer fashion to produce a 3D Stereolithography (SLA):3 Originally printing of a precisely tailored lattice product. To begin the process, a computer- introduced in the early 1980s, SLA structure with defined parameters. aided design (CAD) model is digitally is often referred to as the first rapid DIW customized modifications can created using data from sources including prototyping processing technology.4 be systematically incorporated on the photographic, computed tomography (CT) In SLA, a build platform is submerged macro-, meso-, micro- and nanometer and magnetic resonance imaging (MRI) in a vat of photocurable resin. With levels to allow printing of an array of images or by using 3D rendering software. exposure to a concentrated ultraviolet materials at room temperature with Once the digital CAD model is light beam, layers of this curable resin minimal post processing.11,12 Due to finalized, it is segmented into a set of digital are polymerized and solidified in a its versatility in printing materials slices that are then exported to a readable predetermined CAD pattern. Subsequent and high level of construct design file, exported to a compatible 3D printer layers are printed as the platform is raised customizability, DIW has shown and printed into the final physical model. by microns at a time from the resin. increasing adoption for printing of tissue The printer deposits or fuses successive Selective laser sintering (SLS):5,6 Similar engineering constructs (FIGURE 1).12,13

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syringe pumps

X, Y, Z gantry robot patient-specific, clinical needs, anatomic resulted in positive patient ratings and considerations and limitations of any generated requests to use models in reconstruction. This review describes future consultations.16 The use of these the current application of 3D printing models has been described in primary17 in craniofacial surgery including patient and secondary rhinoplasty18 (FIGURE 3). education, surgical planning, surgical Models can be printed to assist tools and patient-specific implant creation surgeons in preoperative preparation and tissue engineering (FIGURE 2). for the reconstruction of rare FIGURE 1. Schematic of direct ink writing (DIW) craniofacial conditions or anatomically or robocasting 3D printer. Syringe pumps attached Customized 3D Patient Models complex areas. Engel et al. described to an X, Y, Z gantry robot allow for precise printing Using CAD/CAM technology, the printing of a skull model of a of ceramic-based materials in 3D. One of many 3D surgeons commonly manufacture 3D patient with hypertelorism in order to printing modalities, DIW is commonly employed in 3D printing of tissue engineering scaffolds. craniofacial models from STL files optimize surgical approach and reduce converted from biologic images and surgery time.19 These models offer scans. This process can be completed substrate for practice and planning not Limited access to resources and through a commercial vendor or available with cadavers as congenital high cost were previously prohibitive through in-house manufacturing. One conditions are commonly treated in the dissemination of this technology, advantage of 3D printed models over at the pediatric age and congenital but recent advances in 3D printing 2D images is the ability to visualize facial deformities are rarely present technology have made it more widely the relationships between points and in a cadaver. Longfeld et al. 3D available. In particular, the decreasing surfaces in 3D, which is particularly printed a temporal bone training cost of 3D printers combined with the advantageous in a craniofacial context model that was used to train surgeons increasing array of hardware options where more complicated relationships through preoperative simulation.20 has resulted in a growing adoption and exist compared to other anatomical Additionally, 3D printed, patient- implementation of 3D printing in both areas of reconstruction. Furthermore, specific models can be sterilized academic and commercial settings. bony surgery can be performed on and brought to the operative field Plastic surgery has witnessed the advent craniofacial skeletal models, effectively to serve as intraoperative guides of 3D printing across the reconstructive simulating critical parts of the when reconstructing complex 3D process, from surgical planning procedure. The opportunity to simulate geometries. These models can templates to implantable biomaterials the procedure provides a critical be particularly advantageous in and regenerative technologies.14 advantage to surgical preparation and uncommonly performed reconstructions Many surgeons are integrating 3D planning in cases where the patient’s or procedures requiring exact 3D printing into their workflow as condition is rare, the anatomical precision. Although 3D printed commercial and in-house systems of defect is complex or the surgical models are commercially available 3D manufacturing harness computer- approach is unique/customized. from third-party vendors, in-house aided design and manufacturing Commercially available, custom 3D manufacture of patient-specific models (CAD/CAM) to translate acquired printed patient models are being used in using preoperative scans can further biologic scans into applied 3D tools. patient consultation and reconstructive streamline the processes. Rather than At present, 3D printing has myriad planning in cosmetic surgery, particularly using commercial services, in-house applications in plastic surgery, and in rhinoplasty.15 In these systems, CT and design and fabrication can lead to there is immense potential for greater photographic images of the patient are reduced costs and permit greater integration into clinical practice. used to print preoperative and planned control by the surgeon on the design Ultimately, plastic and reconstructive postoperative 3D models of patients’ faces and precision of their reconstruction. surgeons must remain actively involved and are used to discuss goals and explain Flores et al. described an in-house in the planning, design and application reconstructive options. Klosterman and technique for design and fabrication of 3D printing technologies as they are Romo reported that use of these 3D of models for ear reconstruction21 uniquely positioned to understand the printed models in patient consultations and rhinoplasty22 (F IG u re 4).

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Patient education Patient data Surgeon training Sterilizable models (CT/MRI/3D photo) Intraoperative models Models for fixation plate prebending

Cutting guides Templates Splints CAD/CAM Custom plates Patient-specific implants Custom implants Combined positioning systems

3D printed scaffolds 3D printing Tissue engineering Live bioprinting

FIGURE 2. Schematic of workflow from patient data to 3D printing and its various applications in plastic and reconstructive surgery.

The use of patient-specific Surgical Templates and Guides these cases, positioning is crucial because models is not limited to soft misplacement within the occlusal plane tissue reconstruction; sterilized Maxillary and Mandibular might result in an inability to use the stereolithographic models have been Reconstruction reconstructed bone for fixation of the used to fit operative hardware such as 3D modeling and printing have prostheses. Additionally, by preoperatively titanium plates. Plates can be prebent allowed for major advances in designing cutting guides that determine and custom molded to the patient microvascular free-flap reconstruction, the angle of osteotomies that create pieces for reconstruction during routine particularly of the upper and lower jaw. that reassemble the desired reconstruction, and complex craniofacial trauma, One of the more sophisticated applications this technique minimizes ischemia time significantly reducing operative time of this technology to jaw reconstruction of the harvested flap. Finally, guides and increasing operative precision.23–25 involves the microvascular reconstruction are fabricated for precise placement of These models can be constructed of the mandible/maxilla with concurrent osteointegrated implants directly into the using mirror-image duplication of placement of osteointegrated implants fibula flap prior to inset onto the face, the contralateral, unaffected side, and prosthetics, restoring occlusion and such that a dental prosthesis can then providing a target bony form to which providing full oral restoration in a single be placed immediately after surgery, a a titanium plate can be molded. intervention or Jaw in a Day (3D Systems, service that would not be feasible using In more complex reconstructions Rock Hill, S.C.).32 Ordinarily, the time traditional reconstructive techniques. of large or composite defects such between bony and soft tissue microvascular The authors attribute their development as free-fibula flap reconstruction, reconstruction of the jaw and full dental of this method to the clinical demand CAD/CAM has been used to design restoration can take several months or of successfully completing increasingly osteotomies, and 3D models are even years.32 Levine et al. published their complex head and neck surgery while printed, sterilized and used to prebend protocol for Jaw in a Day, whereby they limiting patient morbidity and the time to fixation plates prior to harvesting of describe the use of virtual surgical planning full-functional restoration. This method the flap to decrease ischemia time.26 (VSP) in order to design and prefabricate has been adopted by other large academic Particularly, this technology may be patient-specific cutting guides to allow centers and has likewise been applied useful when the original architecture for the precise and expeditious harvesting to reconstruction of large neoplastic of the mandible has been altered or and repositioning of a fibular-free flap for resections of the edentulous mandible destroyed.27 The use of models for mandibular reconstruction. The authors and to reconstruction of the maxilla.32–36 accurately bending fixation plates note that 3D technology facilitates the Through this technique, the authors has also been applied in cranial28 shaping of the fibula to allow for a one- cited the ability to better restore form and and orbital wall reconstruction.29–31 stage, patient-specific reconstruction. In function of the jaw by optimizing angle

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FIGURE 4. 3D printed auricular segments based on unaffected contralateral side can be used as intraoperative guides for shaping of costal cartilage in auricular reconstruction.

FIGURE 3. 3D photograph scan data can be used including revision craniosynostosis, facial In orthognathic surgery, VSP and to generate a computer representation of patients’ bipartition, four-wall box osteotomy, CAD/CAM have also been used to faces (left). These scans can be digitally manipulated reduction cranioplasty and distraction preoperatively design and 3D print to create 3D printed custom patient models of planned 40 post-op rhinoplasty results (right). Commercial 3D osteogenesis. Proponents of VSP-CAD/ custom, patient-specific occlusal 41 44 custom models are used in patient education and CAM note favorable safety and cost splints. Schneider et al. conducted can be fabricated and sterilized in-house to serve as profiles resulting from decreased operative retrospective randomized controlled trials intraoperative models. time42 due to the precision of pretemplated of VSP-designed, 3D printed splints that osteotomies, however, these studies are demonstrated less required intraoperative pending and it is certainly possible that modification of splints to achieve and positioning with an overall decreased dependence on this technology may, in desired occlusion, decreased operating number of final procedures and cost fact, increase the cost of care for certain times while resulting in high-fidelity, reduction. They note that the procedure procedures. Therefore, it is critical to postoperative orthognathic outcomes is not without disadvantages, stating that demonstrate a measurable benefit to compared to conventional methods.45 there may be a steep learning curve to the patient outcomes or cost of care in order Given that conventional methods require design, implementation and effectiveness to justify the use of this technology. multiple steps that may amplify errors of 3D printing technology. Additionally, in the creation of intraoral splints, there loss of the fibular flap may result in loss of Orthognathic Surgery remains interest in the development dental implants and prostheses, though VSP-CAD/CAM and 3D printing of in-house protocols for splint design long-term rates of implant survival have have seen adoption in orthognathic and manufacture via 3D printing.46 yet to be assessed. As such, long-term surgery as well and have become studies regarding the survival of Jaw in a commonly available through commercial Vascularized Composite Tissue Day dental implants remain necessary.35 vendors. Polley and Figueroa published Allotransplantation their experience with an intraoperative The application of VSP in Cranial Reconstruction positioning system that combines craniofacial vascularized composite tissue 3D cutting guides have also been CAD/CAM-designed drilling guides, allotransplantation (VCA) illustrates applied in cranial reconstruction. detachable occlusal guides and occlusal its ability to facilitate the planning and Dorafshar et al. published their experience splints.44 These cutting guides may be of execution of high-complexity, high- using 3D printed guides for cranial particular benefit, but are not limited to precision, multidimensional procedures. reconstruction in patients with metopic, use in orthognathic procedures involving In addition to conventional 3D CT unicoronal and multisutural synostosis.37 complex movements of the jaws or in craniofacial skeletal and vascular evaluation Their group described the application of patients with severe facial scoliosis in commonly employed in VCA, VSP has VSP and 3D printed guides for cranial which the ideal midline is not easily been used to design and translate planned cuts in a patient with late-presenting realized. As discussed with other forms of osteotomies via the printing of customized scaphocephaly38 as well as multisuture and craniomaxillofacial surgery, investigation donor cutting guides (FIGURES 5). In revision craniosynostosis.39 They propose in this area suggests that preoperative bimaxillary facial transplantation, lack that because of their center’s experience evaluation of dental occlusion with VSP- of conventional landmarks may interfere and familiarity with VSP-CAD/CAM CAD/CAM results in more accurate with the ability of a surgical team to applications, use of 3D printing technology correction compared to conventional orthotopically attach the transplanted facial could improve operative results and methods, decreased operating time, saved structure onto the cranial base. Dorafshar may be indicated in complicated cases costs and favorable safety profile.42–44 and Rodriguez et al. demonstrated in a

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viability, compatibility and time-saving potential of VSP-CAD/CAM systems in creating cutting guides and PSIs with favorable mechanical properties52 without increased risk for infection53 that may reduce the need for pre- and postoperative orthodontic treatment.

Orbital Wall Reconstruction FIGURE 5A. Virtually designed cutting guides for the FIGURE 5B. Virtually planned nasal and genial donor skeleton (yellow). Custom-tailored cutting guides skeletal segments to be removed (green) and The ability to customize implants to (pink) for precise guidance of osteotomies. (Printed with orbitozygomatic regions to be augmented (green). complex geometries based on CT data permission and copyrights retained by Eduardo D. Custom-tailored cutting guides (pink) designed to achieve has made 3D printing of PSIs particularly Rodriguez, MD, DDS.) precise bony segments. (Printed with permission and suited to orbital wall reconstruction. In copyrights retained by Eduardo D. Rodriguez, MD, DDS.) the orbit, a change in orbital volume resulting from an imprecise orbital wall reconstruction can significantly affect sentinel case series that VSP could be Patient-Specific Implants the position of the globe and secondary used to plan and produce cutting guides ocular function.54 Stoor et al. described to perform full-facial osteomyocutaneous Orthognathic Surgery a protocol for the design and placement transplantation (based on the LeFort Conventional methods of surgical of titanium mesh PSI designed with III segment) with six rotational axes in planning and intraoperative fixation CAD/CAM by mirroring the intact a series of five cadaveric cases and one in orthognathic surgery require manual maxilla and orbit.54 Using mirror-imaged clinical case.47 The authors reported bending of titanium plates to rigidly and age-matched control scans, PSIs good to excellent outcomes in five of the fix the maxilla in its new 3D position can be designed to have a high surface six degrees of freedom.48 In a multistep, and rotation. Following orthognathic contact area with intact orbital bone to multiteam procedure, the authors reported surgery, preoperative and postoperative ensure optimal positioning and stability successful translation of virtually planned are commonly employed of the implant. The development of osteotomies to end product. While the and may further be required to correct increasingly robust, safe, accurate orbital authors acknowledge the challenges of imperfections in occlusion secondary wall PSIs continues to be an active timing computer reconstruction with regard to relapse or suboptimal restoration area of development, however, because to suddenly available donors in a trauma of dental relationships. 3D imaging, of the delicate nature of orbital wall setting, they and other authors advocate for planning and prototyping technology reconstruction compared to conventional the usefulness of VSP and 3D printing in is evolving such that concurrent to scan resolution, small inaccuracies can be VCA, especially in cases of known, stable the development of the 3D printed amplified in the CAD/CAM process.55–57 recipients.49 Overall, in the rapidly evolving strategies described above, there has VCA landscape, there has been increasing been rapid development of patient- Cranial Reconstruction implementation of VSP and CAD/ specific implants (PSI) that may The benefit of 3D printed PSIs in CAM technology. However, the ability obviate the need for splint placement cranial reconstruction can be readily of current CAD/CAM-generated guides or prebending of titanium plates appreciated given the limitations may be limited in their ability to account based on models.50 Fabricating PSI of autogenous reconstruction and for dynamic movement of a multisegment, via additive manufacturing can result conventional reconstructive implants of composite tissue structure. Outcomes related in accurate translation, rotation and the calvarium. Limited size and stock of to the influence of soft tissue and muscles fixation of the maxilla that do not donor bone and decreasing osteogenic of mastication on allograft function, for require the use of wafers or splints.51 capacity of the dura after 12–18 months, example, have not been evaluated48 and the Adoption of 3D printed cutting guides particularly across critically sized defects, utility of CAD/CAM in VCA continues and PSI have not been widely adopted can present challenges to successful to be an active area of development. as of yet, but reports underscore the cranial reconstruction.58 To this end,

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Dean et al. presented a protocol that utilizes additive manufacturing in order to print custom, sterilizable plates that can be used in cranial reconstruction.59 They found that 3D printed implants were less expensive and better fitting, thus more likely to protect the brain FIGURE 6A. CAD model of tissue engineering FIGURE 6B. Resulting 3D printed scaffold from trauma and infection and more scaffold. Micro-, meso- and macrostructure of 3D comprised of 100% B-TCP. Lattice structure allows for cosmetically suitable compared to printed scaffolds can be precisely optimized. osseoconduction of osteoprogenitor cells in vivo. manually generated skull plates.60 Likewise, Gordon et al. presented their experience performing single-stage site morbidity, limited tissue stock and Optimization studies have delineated cranioplasty for benign and malignant shape, incomplete graft take, prolonged ideal ratio of pore to strut size of skull neoplasms using 3D printed, patient- operative time and extended hospital stay. lattice structures in order to facilitate specific implants.61 The authors reported Prosthetic replacements are challenged osteoconduction and osteoinduction no implant-related complications at by infection, fracture, exposure and the of native osteoprogenitor cells.70 This one to 16 months and ideal long-term morbidity of extrication and replacement. lattice-based scaffold design further aesthetic results, with quantitative In craniofacial reconstruction, the allows for scaffolds to be used as carriers analysis showing correction of soft tissue combination of scaffold support for osteoinductive pharmacologic agents, defects.62 Further, these cranial implants constructs, osteogenic factors and stem which further promote differentiation have been successfully modified to cell therapies are popular novel avenues and proliferation of regenerated integrate a built-in hydrocephalus shunt of investigation in this rapidly evolving bone.67,69,71,72 Short-term studies of valve device in human patients.63 landscape.64,65 By combining CAD/CAM these scaffolds additionally suggest strategies and biomaterial engineering, that 100% β-TCP scaffolds undergo 3D Printing and Tissue Engineering well-characterized materials such as improved remodeling and resorption in beta-tricalcium phosphate (β-TCP) can vivo, suggesting favorable degradation 3D Printed Biomaterials be geometrically optimized to achieve of these constructs.69 Meanwhile, these The ideal bioregenerative construct ideal regenerative capacity, degradation scaffolds have been shown to be safe should be biocompatible, facilitate profiles and macrogeometry, customizable in animal models, without scaffold tissue regeneration, have favorable to any defect shape or size66 (FIGURES 6). fragmentation, ectopic bone growth or degradation kinetics and eventually be These customizable 3D printed scaffold negative impact on craniofacial sutures. replaced by vascularized, uninterrupted constructs have been investigated in a 3D printing technologies have also native tissue. 3D printing technology variety of contexts including craniofacial been shown to effectively regenerate has a potentially unique role in the field reconstruction and stand to address cranial bone in immature animal models, of tissue engineering as the macro-, many of the limitations associated with notably without disruption of growing meso, micro- and nanoarchitecture of conventional reconstructive strategies. cranial sutures.69,70 Pediatric craniofacial scaffolds can be tailored to optimize Adult large animal models have reconstruction is a particularly challenging osteoconduction, vascularization and demonstrated that these scaffolds can area of investigation, as pediatric patients absorption. Furthermore, 3D printed regenerate bone across even critically sized tend to have more limited donor- osteoinductive constructs can be craniomaxillofacial defects of the cranium, bone stock and shape.58 Additionally, customized to fit and fill any size or shaped mandible and maxilla.67,68 In contrast to the growth and development of the defect, providing an ideal pathway to unfilled defects, these 3D printed scaffolds pediatric skeleton traditionally requires personalized hard tissue replacement have been shown to regenerate bone multiple operations, especially when constructs. The significance of potentially across critically sized craniotomies and xenografts are used. Degradable β-TCP regenerating bone and cartilage in the surgically created clefts with evidence scaffolds have the potential to address face and skull cannot be overstated. of maturing lamellar morphology and this important need, though thus far Autogenous sources are limited by donor vascularization of newly formed bone.69,70 investigation in animals has been limited

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Tissue harvest Differentiated cells Implantation Hydrogel matrix Differentiation/ growth factors

Stem cell isolation/expansion Extrusion/3D printing Scaffold construct Bioreactor incubation

FIGURE 7. Schematic representation of cartilage/bone bioprinting process. Stem cells are isolated and harvested from donor tissue, suspended in a hydrogel matrix, 3D printed into a scaffold construct and incubated in a bioreactor prior to in vivo implantation. to the short term — long-term safety vascularized and incorporated with chondrocyte or adipocyte precursor cells. and efficacy studies through the time of minimal donor site morbidity and no Initial reports demonstrate good ability facial maturity are currently underway. permanent alloplastic implants. of 3D printing to generate constructs in 3D printing technology has also been The practice of bioprinting is complex 3D configurations that ultimately applied in efforts to generate anatomic complicated and the critical steps of allow for proliferation of human cells.79,80 cartilage tissue. One area of investigation the process are under active refinement However, the technology remains in early is in temporomandibular joint (TMJ) disc (FIGURE 7). Stem cells are first harvested development, with no current optimized reconstruction in the treatment of TMJ from the patient and expanded in protocol for the combination of scaffold disc thinning or following discectomy for vitro. The cells are suspended in a design, production and chondrocyte severe TMJ disease. Like in other areas hydrogel matrix and printed into a induction yet established.81 Furthermore, of tissue engineering, investigation of scaffold containing the appropriate the mechanical integrity of the scaffolds TMJ disc regeneration has incorporated cell signaling agents and placed into a and generated cartilage is an area of active construction of various flexible scaffold bioreactor, an incubator that provides development as many cartilage constructs components with cell therapies. 3D printers the stem cell the necessary oxygen undergo contracture and see progressively have been used to print scaffolds to more and nutrients to differentiate and structural deformity over time. closely approximate TMJ disc fibrocartilage proliferate. The scaffold with the now Bioprinting of bone tissue has also microstructure and hence better reproduce differentiated, mature and expanded seen advancement in recent years. Like mechanical properties of tissue engineered cells are implanted into the patient. cartilage bioprinting, bone bioprinting discs.73 Investigation in this area remains Cartilage bioprinting has been combines hydrogel-based matrices with preliminary, however, and groups have investigated in total auricular bone-marrow derived mesenchymal cells investigated different extracellular matrix reconstruction, where conventional and has shown promise in fabricating formulations,74 scaffold cell-seeding reconstruction using a costal cartilage mechanically stable 3D printed methods,75 3D delivery of growth factors76 framework is technically demanding, constructs with viable bone-precursor and scaffold-free self-assembling discs.77 spatially complex and requires multiple cells. The matrix as well as cellular operations, often with less than ideal components of this strategy continue Bioprinting restoration of form and function.78 Soft to be refined.82–84 For example, Fischer Additive fabrication of cellular, tissue scaffold-based tissue engineering et al. investigated the combination biointegratable live tissue is another continues to be challenging secondary of collagen I with agarose hydrogels active area of investigation and to contracture or necrosis of poorly in order to improve the mechanical represents some of the most sophisticated vascularized cartilage and soft tissue. stiffness and printing contours of their applications of 3D printing. Ideally, Protocols have been proposed for 3D printed constructs.85 Furthermore, they bioprinting of human cells suspended in printing of cartilage that use hydrogel- report that the addition of collagen a biodegradable matrix would produce a (cellulose or agar) based scaffolds that give induced changes in cell morphology and tissue construct that could be implanted, the structural foundation for seeding of enhanced osteogenic differentiation.

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Summary/Discussion overhead costs for 3D manufacturing well as other novel permutations of 3D This review has described the ways equipment, software and training remain a printing will continue to broaden our in which 3D printing technology has significant obstacle for many. While many surgical reconstructive horizons.92 Surgeons been incorporated into several aspects reports suggest the cost-effectiveness of stand to overcome longstanding obstacles in of plastic surgery reconstruction. From incorporating 3D printing into surgical craniofacial plastic surgery as they continue patient-centered models to intraoperative protocols, 3D printing may initially increase to adopt, evaluate and improve the templates to CAD/CAM cutting guides, operative costs.86 On the other hand, 3D possibilities of 3D printing technology. n implants and tissue engineering constructs, printing of small-sized standard objects 3D printing technology has demonstrated such as the printing of cutting guides and references 1. Doraiswamy A, Narayan R, Harris M, Qadri S, Modi R, an overall ability to accurately translate orthognathic splints are proving increasingly Chrisey D. Laser microfabrication of hydroxyapatite-osteoblast- 3D imaging data into customizable tools cost-effective compared to commercially like cell composites. J Biomed Mater Res A 2007 Mar that can be leveraged by surgeons. sourced services.87,88 While 3D printing 1;80(3):635–43. 2. Harris M, Doraiswamy A, Narayan R, Patz T, Chrisey Across these various applications, patient-centric models and VSP-designed D. Recent progress in CAD/CAM laser direct-writing of 3D printing stands to be a less labor- cutting guides are commonly outsourced to biomaterials. Mater Sci Eng C 2008;28(3):359–65. doi: intensive, streamlined and high-fidelity commercial providers, the above described 10.1016/j.msec.2007.04.013. 3. Williams JM, Adewunmi A, Schek RM, Flanagan CL, solution to complex 3D visualization and reports demonstrate that active surgeon Krebsbach PH, Feinberg SE, et al. Bone tissue engineering reconstruction. By addressing 3D planning collaboration in the clinical applicability, using polycaprolactone scaffolds fabricated via selective laser preoperatively, 3D printing has been shown relevance and testing can drive innovation sintering. Biomaterials 2005 Aug;26(23):4817–27. Epub 2005 Jan 23. to decrease OR times, which ultimately in 3D printing reconstructive technology. 4. Chia HN, Wu BM. Recent advances in 3D printing of can result in significant cost reduction. Further, in-house design and fabrication of biomaterials. J Biol Eng 2015 Mar 1;9:4. doi: 10.1186/ VSP has been demonstrated to produce 3D printed solutions have been achieved s13036-015-0001-4. eCollection 2015. 5. Kalita SJ, Bose S, Hosick HL, Bandyopadhyay A. more predictable outcomes compared at many centers by leveraging available Development of controlled porosity polymer-ceramic to conventional planning methods in resources to address clinical need.21,22,49 composite scaffolds via fused deposition modeling. Mater orthognathic surgery and has begun to As 3D printing becomes more widely Sci Eng C 2003;23(5):611–20. Doi: 10.1016/S0928- 4931(03)00052-3. be a de facto part of VCA protocols and adopted, important regulatory and safety 6. Tsang VL, Bhatia SN. Three-dimensional tissue fabrication. other challenging reconstructions due to questions will need to be addressed.89 To Adv Drug Deliv Rev 2004 Sep 22;56(11):1635–47. its ability to account for multiple spatial that end, more high-quality studies that 7. Chrisey DB. The power of direct writing. Science 2000;289(5481):879–81. doi: 10.1126/ and anatomical variables and facilitate directly compare 3D printed approaches science.289.5481.879. intersurgeon communication to ultimately to conventional methods are necessary. 8. Smay JE, Lewis JA. Solid free-form fabrication of 3-D ceramic reduce pre- and postplanning variability. 3D Future directions for 3D printed structures. Ceramics and composites processing methods. 1st ed. Hoboken, N.J.: Wiley; 2012:459–84. printing is becoming increasingly available technologies include development and 9. Winder J, Bibb R. Medical rapid prototyping technologies: in a commercial setting, and the ability to refinement of both computer aided design State of the art and current limitations for application in oral design custom implants and reconstructive and manufacturing. While at present and maxillofacial surgery. J Oral Maxillofac Surg 2005 Jul;63(7):1006–15. solutions is shaping the demands and most commonly used VSP systems take 10. Jardini AL, Larosa MA, Maciel Filho R, de Carvalho approaches of industry and academic leaders into account one or two tissue systems Zavaglia CA, Bernardes LF, Lambert CS, et al. Cranial alike. Lastly, CAD/CAM and 3D printing (bone, vasculature or soft tissue) in reconstruction: 3D biomodel and custom-built implant created using additive manufacturing. J Craniomaxillofac are integral parts of novel tissue engineering isolation, combined tissue modeling and Surg 2014;42(8):1877–84. doi.org/10.1016/j. strategies, as they make it possible to printing that takes into account dynamic jcms.2014.07.006. customize organic and inorganic constructs interactions of muscle, soft tissue and 11. Wauters LD, San Miguel-Moragas J, Mommaerts 48,90 MY. Classification of computer-aided design–computer- on a micro-, meso- and macroscale. bone or incorporates multifunctional aided manufacturing applications for the reconstruction While prevalence of 3D printing in printed technology91 will prove crucial for of cranio-maxillo-facial defects. J Craniofac Surg reconstructive surgery is growing in certain increasingly sophisticated reconstructions, 2015 Nov;26(8):2329–33. doi: 10.1097/ SCS.0000000000001845. contexts, i.e., commercially and at highly made possible as 3D printed technology 12. Kang S-H, Kim M-K, Kim H-J, Zhengguo P, Lee S-H. resourced academic centers, widespread evolves. Furthermore, 3D printing Accuracy assessment of image-based surface meshing for adoption of this technology may be technology itself continues to rapidly evolve volumetric computed tomography images in the craniofacial region. J Craniofac Surg 2014 Nov;25(6):2051–5. doi: limited by cost, infrastructure and surgeon — development of in situ or intraoperative 10.1097/SCS.0000000000001139. familiarity with this technology. At present, bioprinting directly into surgical fields as 13. Lopez CD, Witek L, Torroni A, Flores RL, Demissie

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follow-up. J Craniomaxillofac Surg 2018 Oct;46(10):1814– 67. Bekisz JM, Flores RL, Witek L, Lopez CD, Runyan CM, printed porous tissue bioscaffolds for craniofacial soft 1817. doi: 10.1016/j.jcms.2018.07.011. Epub 2018 Jul 23. Torroni A, et al. Dipyridamole enhances osteogenesis of three- tissue reconstruction. Otolaryngol Head Neck Surg 2015 54. Stoor P, Suomalainen A, Lindqvist C, Mesimäki K, dimensionally printed bioactive ceramic scaffolds in calvarial Jan;152(1):57–62. doi: 10.1177/0194599814552065. Danielsson D, Westermark A, et al. Rapid prototyped patient defects. J Craniomaxillofac Surg 2018 Feb;46(2):237–244. Epub 2014 Oct 3. specific implants for reconstruction of orbital wall defects. doi: 10.1016/j.jcms.2017.11.011. Epub 2017 Nov 21. 80. Kang H-W, Lee SJ, Ko IK, Kengla C, Yoo JJ, Atala A. A 3D J Craniomaxillofac Surg 2014 Dec;42(8):1644–9. doi: 68. Lopez CD, Bekisz JM, Corciulo C, Mediero A, Coelho PG, bioprinting system to produce human-scale tissue constructs 10.1016/j.jcms.2014.05.006. Epub 2014 May 23. Witek L, et al. Local delivery of adenosine receptor agonists with structural integrity. Nature Biotechnol 2016;34(3):312. 55. Callahan AB, Campbell AA, Petris C, Kazim M. Low- to promote bone regeneration and defect healing. Adv Drug 81. Nayyer L, Patel KH, Esmaeili A, Rippel RA, Birchall cost 3D printing orbital implant templates in secondary Deliv Rev 2018 Jun 18. pii: S0169-409X(18)30149-2. doi: M, O’toole G, et al. Tissue engineering: Revolution and orbital reconstructions. Ophthalmic Plast Reconstr 10.1016/j.addr.2018.06.010. [Epub ahead of print]. challenge in auricular cartilage reconstruction. Plast Reconstr Surg 2017 Sep/Oct;33(5):376-380. doi: 10.1097/ 69. Lopez CD, Coelho PG, Witek L, Torroni A, Greenberg Surg 2012 May;129(5):1123–37. doi: 10.1097/ IOP.0000000000000884. MI, Cuadrado DL, et al. Regeneration of a pediatric PRS.0b013e31824a2c1c. 56. Day KM, Phillips PM, Sargent LA. Correction of a alveolar cleft model using 3D printed bioceramic scaffolds 82. Wenz A, Borchers K, Tovar GE, Kluger PJ. Bone matrix posttraumatic orbital deformity using three-dimensional and osteogenic agents: Comparison of dipyridamole and production in hydroxyapatite-modified hydrogels suitable for modeling, virtual surgical planning with computer-assisted rhBMP-2. Plast Reconstr Surg 2019 May 7. doi: 10.1097/ bone bioprinting. Biofabrication 2017 Nov 14;9(4):044103. design and three-dimensional printing of custom implants. PRS.0000000000005840. [Epub ahead of print]. doi: 10.1088/1758-5090/aa91ec. Craniomaxillofac Trauma Reconstr 2018 Mar;11(1):78–82. 70. Maliha SG, Lopez CD, Coelho PG, Witek L, Cox 83. Wenz A, Janke K, Hoch E, Tovar GE, Borchers K, doi: 10.1055/s-0037-1601432. Epub 2017 Apr 3. M, Meskin A, et al. Bone tissue engineering of the Kluger PJ. Hydroxyapatite-modified gelatin bioinks for bone 57. Huang Y-H, Seelaus R, Zhao L, Patel PK, Cohen M. growing calvarium using dipyridamole-coated 3D printed bioprinting. BioNanoMaterials 2016;17(3–4):179–84. doi. Virtual surgical planning and 3D printing in prosthetic orbital bioceramic scaffolds: Construct optimization and effects org/10.1515/bnm-2015-0018. reconstruction with percutaneous implants: A technical case to cranial suture patency. Plast Reconstr Surg Glob 84. Fedorovich NE, De Wijn JR, Verbout AJ, Alblas J, Dhert report. Int Med Case Rep J 2016 Oct 31;9:341–345. Open 2018 Apr; 6(4 Suppl):80–81. doi: 10.1097/01. WJ. Three-dimensional fiber deposition of cell-laden, viable, eCollection 2016. GOX.0000533966.01882.35. patterned constructs for bone tissue printing. Tissue Eng Part A 58. Lam S, Kuether J, Fong A, Reid R. Cranioplasty for large- 71. Ishack S, Mediero A, Wilder T, Ricci JL, Cronstein BN. Bone 2008 Jan;14(1):127–33. doi: 10.1089/ten.a.2007.0158. sized calvarial defects in the pediatric population: A review. regeneration in critical bone defects using three-dimensionally 85. Duarte Campos DF, Blaeser A, Buellesbach K, Sen KS, Craniomaxillofac Trauma Reconstr 2015 Jun;8(2):159–70. printed β-tricalcium phosphate/hydroxyapatite scaffolds Xun W, Tillmann W, et al. Bioprinting organotypic hydrogels doi: 10.1055/s-0034-1395880. Epub 2014 Nov 20. is enhanced by coating scaffolds with either dipyridamole with improved mesenchymal stem cell remodeling and 59. Dean D, Min KJ, Bond A. Computer aided design of large- or BMP-2. J Biomed Mater Res B Appl Biomater 2017 mineralization properties for bone tissue engineering. Adv format prefabricated cranial plates. J Craniofac Surg 2003 Feb;105(2):366–375. doi: 10.1002/jbm.b.33561. Epub Healthc Mater 2016 Jun;5(11):1336–45. doi: 10.1002/ Nov;14(6):819–32. 2015 Oct 29. adhm.201501033. Epub 2016 Apr 13. 60. Volpe Y, Furferi R, Governi L, Uccheddu F, Carfagni M, 72. Lopez C, Bekisz J, Corciulo C, Mediero A, Coelho P, 86. Tack P, Victor J, Gemmel P, Annemans L. 3D-printing Mussa F, et al. Surgery of complex craniofacial defects: Witek L, et al. Local delivery of adenosine receptor agonists techniques in a medical setting: A systematic literature review. A single-step AM-based methodology. Comput Methods to promote bone regeneration and defect healing. Adv Drug Biomed Eng Online 2016 Oct 21;15(1):115. Programs Biomed 2018 Oct;165:225–233. doi: 10.1016/j. Deliv Rev 2018 Jun 18. pii: S0169-409X(18)30149-2. doi: 87. Banks J. Adding value in additive manufacturing: cmpb.2018.09.002. Epub 2018 Sep 5. 10.1016/j.addr.2018.06.010. [Epub ahead of print]. Researchers in the United Kingdom and Europe look to 61. Berli JU, Thomaier L, Zhong S, Huang J, Quinones 73. Legemate K, Tarafder S, Jun Y, Lee C. Engineering 3D printing for customization. IEEE Pulse 2013 Nov- A, Lim M, et al. Immediate single-stage cranioplasty human TMJ discs with protein-releasing 3D-printed Dec;4(6):22–6. doi: 10.1109/MPUL.2013.2279617. following calvarial resection for benign and malignant scaffolds. J Dent Res 2016 Jul;95(7):800–7. doi: 88. Schubert C, Van Langeveld MC, Donoso LA. Innovations skull neoplasms using customized craniofacial implants. J 10.1177/0022034516642404. Epub 2016 Apr 6. in 3D printing: A 3D overview from optics to organs. Br J Craniofac Surg 2015 Jul;26(5):1456–62. doi: 10.1097/ 74. Hagandora CK, Gao J, Wang Y, Almarza AJ. Ophthalmol 2014 Feb;98(2):159–61. doi: 10.1136/ SCS.0000000000001816. Poly (glycerol sebacate): A novel scaffold material for bjophthalmol-2013-304446. Epub 2013 Nov 28. 62. Zhong S, Huang GJ, Susarla SM, Swanson EW, Huang temporomandibular joint disc engineering. Tissue Eng 89. Ventola CL. Medical applications for 3D printing: Current J, Gordon CR. Quantitative analysis of dual-purpose, patient- Part A 2013 Mar;19(5–6):729–37. doi: 10.1089/ten. and projected uses. P T 2014 Oct;39(10):704–11. specific craniofacial implants for correction of temporal tea.2012.0304. Epub 2012 Nov 16. 90. Ibrahim A, Suttie M, Bulstrode NW, Britto JA, Dunaway D, deformity. Neurosurgery 2015 Jun;11 Suppl 2:220–9; 75. Almarza AJ, Athanasiou KA. Seeding techniques Hammond P, et al. Combined soft and skeletal tissue modelling discussion 229. doi: 10.1227/NEU.0000000000000679. and scaffolding choice for tissue engineering of the of normal and dysmorphic midface postnatal development. J 63. Gordon CR, Wolff A, Santiago GF, Liebman K, temporomandibular joint disk. Tissue Eng 2004 Nov– Craniomaxillofac Surg 2016 Nov;44(11):1777–1785. doi: Veznedaroglu E, Vrionis FD, et al. First-in-human experience with Dec;10(11–12):1787–95. 10.1016/j.jcms.2016.08.020. Epub 2016 Sep 2. integration of a hydrocephalus shunt device within a customized 76. Tarafder S, Koch A, Jun Y, Chou C, Awadallah MR, Lee 91. MacDonald E, Wicker R. Multiprocess 3D printing for cranial implant. Oper Neurosurg (Hagerstown) 2019 Feb 7. CH. Micro-precise spatiotemporal delivery system embedded increasing component functionality. Science 2016 Sep doi: 10.1093/ons/opz003. [Epub ahead of print]. in 3D printing for complex tissue regeneration. Biofabrication 30;353(6307). pii: aaf2093. Epub 2016 Sep 29. 64. Tevlin R, McArdle A, Atashroo D, Walmsley G, Senarath- 2016 Apr 25;8(2):025003. doi: 10.1088/1758- 92. Ozbolat IT, Yu Y. Bioprinting toward organ fabrication: Yapa K, Zielins E, et al. Biomaterials for craniofacial bone 5090/8/2/025003. challenges and future trends. IEEE Trans Biomed Eng 2013 engineering. J Dent Res 2014 Dec;93(12):1187–95. doi: 77. Vapniarsky N, Huwe LW, Arzi B, Houghton MK, Mar;60(3):691–9. doi: 10.1109/TBME.2013.2243912. 10.1177/0022034514547271. Epub 2014 Aug 19. Wong ME, Wilson JW, et al. Tissue engineering toward Epub 2013 Jan 30. 65. Patel M, Fisher JP. Biomaterial scaffolds in pediatric tissue temporomandibular joint disc regeneration. Sci Transl Med engineering. Pediatr Res 2008 May;63(5):497–501. doi: 2018 Jun 20;10(446). pii: eaaq1802. doi: 10.1126/ the corresponding author, Maxime M. Wang, BA, can be 10.1203/01.PDR.0b013e318165eb3e. scitranslmed.aaq1802. reached at [email protected]. 66. Lopez CD, Witek L, Torroni A, Flores RL, Demissie 78. Tollefson TT. Advances in the treatment of microtia. Curr DB, Young S, et al. The role of 3D printing in treating Opin Otolaryngol Head Neck Surg 2006 Dec;14(6):412– craniomaxillofacial congenital anomalies. Birth Defects 22. Res 2018 Aug 1;110(13):1055–1064. doi: 10.1002/ 79. Zopf DA, Mitsak AG, Flanagan CL, Wheeler M, Green bdr2.1345. Epub 2018 May 20. GE, Hollister SJ. Computer aided-designed, three-dimensionally

OCTOBER 2 0 1 9 677 Specializing in selling and appraising dental practices for over 40 years!

LOS ANGELES COUNTY ORANGE COUNTY OCEANSIDE— Established in 1990 with 4 eq ops in a one story busy shopping center. PPO CANOGA PARK— 25+ years of goodwill GP w/ CORONA DEL MAR— Well established GP with and Cash Only. Grossed approx. $560K in 4 eq ops and 1 plmbd not eq op. Located in a walking distance to the ocean. Consists of 3 eq ops. Grossed $898K in 2018. Net $214K. 2018. NET $181K. Property ID #5267. single story bldg. Proj. approx. $369K for Property ID #5285. 2019. Property ID #5241. RANCHO BERNARDO—With 23 yrs of goodwill LADERA RANCH— Beautiful GP in premier this GP grossed approx. $861K in 2018. Net of CENTURY CITY—GP in 11 story prof med bldg. shopping center. Has 11 eq ops. Grossed $348K. Has 4 eq ops. Prorperty ID 5280. Has 5 eq in a 1,955 sq ft. Grossed approx. $1.9M in 2018. NETSOLD $400K. Property ID 5262. $715K. Buyer’s net of $184K. Property ID CARMEL VALLEY — Price Reduced! Turn key LAGUNA NIGUEL—COMING SOON! 4509. practice with 3 eq ops and 1 plumbed not eq CERRITOS— Located in a busy strip mall, this ORANGE—(Turn-Key) General practice located on an approx. 1,815 sq ft suite. PPO and Cash GP has almost 50 yrs of gdwll. Consists of 6 eq in med/dent building. Has 4 eq operatories. only. Grossed approx. $325K in 2018. ID # ops. Property IDSOLD #5286. Grossed approx. $165K in 2018. Great oppor- 5274. tunity for a full time dentist. Property ID 5277. CULVER CITY— GP w/ 60 yrs of goodwill to RIVERSIDE COUNTY YORBA LINDA— GP established in 1987 con- offers is located in 2 story free standing bldg. RANCHO MIRAGE— Beautiful Fee for service Averaging 30 new patient/mo. Grossed $365K sists of 4 eq ops in a 1,150 sq ft suite. PPO & SOLD General / Implant practice located in free in 2018. NET $71K. Property ID #5283. Cash Only. Grossed $658K in 2018. NET $260K. Property # 5258. standing bldg. Has 4 eq ops. . Grossed $1M in DIAMOND BAR— Beautiful GP w/ 6 eq ops in 2018. NET $333K. Property ID #5284. a 2 story building. Grossed approx. $434K in WESTMINSTER/FOUNTAIN VALLEY— Estab- lished in 1978 paperless GP in 2 story free 2018. Long term lease. Property ID #5279. TEMECULA - Pedo and Ortho Practice! It’s standing bldg. Grossed $737K in 2018. Has DUARTE— GP established in1964 located in a reasonable rent. Property ID #5291. located in a duplex single story building. 2 story mixed bldg. Grossed $404K in 2018. Grossed $1.7M with a Buyer’ net of $712K. NET $73K. Property ID #5183. PPO/Cash/Denti-cal. Has 8 eq ops in a 3,500 sq ft office. Property ID # 5243. GRANDA HILLS— With 50 yrs of goodwill this SAN DIEGO COUNTY general practice grossed approx. $328K in TEMECULA—Absentee owner GP with 2 GP CARLSBAD— This beautiful practice has over 22 2018. NET $206K. Property #5276. Associates. Has 4 eq ops in busy shopping yrs of goodwill. Has 4 eq ops in a 1,800 sq ft LONG BEACH —GP w/ 35 yrs goodwill. Has 3 suite. Fee for service office. Grossed approx. center. Grossed $327K in 2018. ID 5259. $440K for 2018. Property ID # 5256. eq ops in a 1,698 sq ft suite. Grossed $336K in LA QUINTA— Price Reduced!! Well estab- 2018. NET $122K. Property ID #5282. CARMEL VALLEY — Price Reduced! Turn key lished GP with over 8 years of goodwill. This practice with 3 eq ops and 1 plumbed not eq on LYNWOOD— GP in single story busy shopping modern designed practice has 8 eq ops. On a an approx. 1,815 sq ft suite. PPO and Cash only. the busiest major intersection. Grossed ap- center. Absentee owner. Grossed $570K in Grossed approx. $325K in 2018. ID # 5274. 2018. NET $255K. Property ID #5264. prox. $1.6M for 2018. NET $568K. Property CHULA VISTA (Turn-Key) —Well laid out prac- ID #5130. ROWLAND HEIGHTS— Estab. in 2009, this GP tice in a 2 story med/dent building. Has 3 eq is located in a 1 story free standing bldg. operatories and 1 plumbed not eq. On a ap- SAN BERNARDINO — General practice located prox. 1,400 sq ft suite. Grossed approximately Grossed $772K in 2018. NET $225K. Property in single story free standing bldg w/ 4 eq ops. $588K in 2018. Great potential for a full time Seller owns building. Grossed $401K in 2019. ID 5278. dentist. Property ID #5273. Property ID #5289. TORRANCE— Located right off the PCH, this EL CAJON - GP + Real State. Consists of 5 eq GP is Collecting $43K in monthly revenues. ops and equipped with 3D Sirona CBCT Digital X UPLAND—Beautiful general practice located in Net of $123K. Property ID #5281. -ray. Grossed over $1M in the past 10 years. 2 story building with 4 equipped operatories. NET $365K. Property ID # 5265. Grossed $943K in 2018. Buyer’s net of $221K.

Property ID #5237.

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CONTACT US FOR A FREE CONSULTATION WWW.CALPRACTICESALES.COM Phone: (800) 697-5656 CA BRE #00283209 RM Matters CDA JOURNAL, VOL 47, Nº10

Workers’ Compensation: Your Obligations as an Employer TDIC Risk Management Staff

he responsibilities of dental regarding her attendance and arriving practice owners extend far Your insurance carrier late for work. On this occasion, the beyond patient care. As an employee failed to show up for her employer, you also have an can help you determine the scheduled shift. The office manager obligation to ensure you are specific obligations in your called the employee to determine why Tfollowing workers’ compensation laws. state, such as compliance she hadn’t arrived, but was unsuccessful Workers’ compensation insurance in making contact with her. Later that provides state-mandated benefits to postings, statute of day, the office received a fax from the employees who suffer an injury or illness limitations and injury office of an orthopedic surgeon advising that arose out of or occurred in the course reporting requirements. that the employee would be off work and scope of employment. Your insurance for several months. Eventually, the carrier can help you determine the office manager reached the employee, specific obligations in your state, such as compliance postings, statute of limitations and injury reporting requirements. Other local, state and federal leave laws run parallel and at times intersect with workers’ compensation laws. The Dentists Insurance Company offers workers’ compensation coverage to California Dental Association members, and TDIC’s Risk Management team has answered a wide range of questions that relate to workplace injuries and answers illnesses, leaves of absence, workplace accommodations and termination. The following are a few common scenarios related to workers’ compensation that have been addressed by analysts.

Scenario 1: Notification of a Workers’ Compensation Injury by a Doctor From one-on-one risk management advice by phone A front-office staff member was to informed consent forms to expert-led seminars, injured at work. The employee did not notify the dentist that she had we’re here to help you practice with confidence. sustained an injury, was currently We are The Dentists Insurance Company. receiving medical treatment or that she was scheduled for upcoming Learn more at tdicinsurance.com/rm surgery. To compound the situation, the employee had performance issues ® that were well documented in her Protecting dentists. It’s all we do. personnel file. The employee had 800.733.0633 | tdicinsurance.com | Insurance Lic. #0652783 been counseled on several occasions

OCTOBER 2 0 1 9 679 OCT. 2019 RM MATTERS

CDA JOURNAL, VOL 47, Nº10

who stated that the communication workers’ compensation laws are medical work status reports and from the orthopedic surgeon stemmed available on the U.S. Department assist with the employee’s return from a back injury she sustained at of Labor’s website at dol.gov/owcp/ to work. However, know that this work. The office manager and the dfec/regs/compliance/wc.htm. is not required once the injured dentist were shocked by the employee’s ■■ Continue to engage with your worker is no longer your employee. assertion that she sustained a workplace employee throughout their ■■ Notify your carrier of an injury injury, as she had not earlier provided leave and attempt to check in involving an employee to any notice to the office. The office with the employee every 30 to begin the process of filing a followed normal protocol in assisting 45 days to obtain a work status workers’ compensation claim. the employee to file a claim for workers’ report. The employee should ■■ Know that in California if compensation benefits. While the office also advise you of the date they an employee was terminated attempted unsuccessfully to obtain more expect to return to work. If the and is represented by an information regarding the employee’s employee is not communicating attorney, the assigned workers’ medical leave, the employee did send with your office, document your compensation adjuster will multiple text messages stating that attempts in the employee’s file. ensure that the employee is she was unable to return and needed treated by a physician in the to extend her leave. The employee’s Scenario 2: Filing a Workers’ medical provider network absence created a strain on overall office Compensation Claim After (MPN). As an employer, operations, and the office ultimately Termination you do not need to authorize decided to terminate her employment. A morning huddle at an office treatment for the employee. In California, even if an employee didn’t begin well and actually ended ■■ Continue to cooperate with is terminated due to personnel issues, with two employees arguing about a the insurer and third-party their workers’ compensation claim can patient scheduling error. One of the administrator during the continue. TDIC’s Risk Management employees left immediately after the investigation of a claim, analyst recommended that the office meeting without notifying anyone. The such as providing a copy of consult with an employment attorney office manager attempted to contact the employee’s personnel for advice on how to proceed. the employee, but the employee refused file and statements to the If facing a similar scenario, TDIC to speak to her and simply hung up. defense attorney. All evidence recommends the following: The employee did not return to work will be used to provide the ■■ Immediately notify your carrier of or notify the office for the remainder defense of the claim. an injury involving an employee of the week. The following week, Every claim is unique and is based to begin the process of filing a the office sent the employee a letter on the specific facts and events leading workers’ compensation claim. recounting her actions and informed up to the employee’s workplace injury. ■■ While workers’ compensation her that they were therefore accepting After filing a workers’ compensation laws vary from state to state, most her resignation. Several weeks later, claim, be sure to stay in contact states generally require employers the employer received a letter from with your carrier so you may better to provide a workers’ compensation a workers’ compensation attorney understand regulations, processes claim form to the employee within representing the ex-employee. The and your role as an employer. one working day after becoming letter advised that the employee was ■■ Be familiar with employer- aware of the work-related injury or filing a cumulative trauma claim required postings and employee illness. In California, for example, related to pain in her neck, shoulders notifications, as you are required once you have knowledge of and thigh, as well as mental stress. to ensure your employees are the injury, you have 24 hours to If facing a similar scenario, aware of workers’ compensation provide your employee with a TDIC recommends the following: and the benefits it may provide. DWC-1 claim form. Additional ■■ Engage in required discussion with ■■ Notify your carrier or third- information on state-specific an injured employee and obtain party administrator within 24

680 OCTOBER 2 01 9 CARROLL “Matching the Right Dentist to the Right Practice” V & C O M P A N Y

4359 SANTA CRUZ GP offering 30+ years of goodwill within 4355 SAN FRANCISCO ENDO Endodontic practice in signature walking distance to the beach! Located in a well-established, building with wealth of referral sources. State-of-the-Art, modern, attractive, single story professional building complex w/ample 1,027 square foot office with 2 fully equipped ops. Well established, parking, good visibility and easy access. 2 doctor days/week, 2 seller with sterling reputation willing to help for smooth transition. hygiene days/week, 380 active patients with approx. 10 new patients/mo. 3 fully equipped ops in 850 sq. ft. Average GR $250K 4331 SAN FRANCISCO GP Downtown SF practice in gorgeous, with Average adj net of $135K. Asking price $150K. remodeled 1,300 office with panoramic views. Suite includes 4 fully equipped ops, reception area, business office, private office, staff 4351 SEBASTOPOL AREA GP & BLDG. Charming practice lounge, lab area, and sterilization area. Beautiful, modern cabinetry situated amidst rolling hills, soaring redwood trees and lush and equipment. 1,600 acStivOeLpDatients with 15-20 new patients/mo. vineyards. Where coffee shops roast their own beans, dining Owner/doctor works 3 days/wk with 5 hygiene days/wk. Average options vary from down-home to gourmet, and people are friendly. gross receipts $738K with average adj. net of $305K. Asking Offering 70+ years of goodwill. Beautiful, modern facility with 3 fully- $495K. equipped ops (room for a 4th op) and digital x-ray. Equipment in pristine condition, most purchased 2016-2018. Dental suite has lots 4358 SAN MATEO GP Unique opportunity to own a downtown of natural light with views looking into a courtyard and garden. 2019 San Mateo GP surrounded by a variety of retail, restaurant, service GR annualized at $679K+ with adj. net of $210K. Average 3.5 and shops generating significant foot traffic and daily doctor days/week and 4 hygiene days/week. 800 active patients, all business draw. 1,498 square foot facility with 4 ops, reception area, fee-for-service. Seller owns the building, it is available for purchase. business office, privaPteEoNfficDeI,NstGaff lounge, lab area, sterilization area, Asking $305K for practice, $425K for building. Owner/doctor willing bathroom, storage & dedicated parking spaces. Family oriented to help for smooth transition. practice with an emphasis on Restorative care. Average annual Gross Receipts $400K+. 4338 PENINSULA PROSTHODONTIC PRACTICE Preeminent 45 year Prosthodontic practice located in mid peninsula 4336 SAN BRUNO GP Legacy practice centrally located in a neighborhood. State-of-the-art 1,242 square foot facility with 5 combined commercial & residential neighborhood, convenient to operatories. Seller willing to help in the transition. Outstanding highways 101, 280, and 380 and close to the BART station. referral sources. AveragPe EGNrosDsINReGceipts $1.3M with 4 doctor-days Elegant, remodeled 1,463 sq. ft. office with 5 fully-equipped ops. & per week. Asking $884K. digital radiography. 5SyOeaLr Daverage Gross Receipts $922K+. 1,000 active patients with an average of 10 new patients per month. Asking 4256 SANTA CRUZ COUNTY GP Seller moving out-of-state and $661K. offering 33 years of goodwill. Wonderful location on major thoroughfare in a charming beach community close to wineries and 4216 SIERRA NEVADA FOOTHILLS 23 year practice located in the water. Tranquil and modern, beautifully appointed, 5 op facility. the heart of the Sierra Nevada foothills in modern building close to Approx. 1,300 active patieSntOs (LaDll fee-for-service). Seller will help for downtown area. 1,024 square foot office with 4 fully- equipped ops., smooth transition. Asking $180K. upgraded major equipment and digital radiography. Average Gross Receipts $890K+ wPithE5N6D%IaNveGrage overhead. Asking price for 4343 CAPITOLA GP Gorgeous, state-of-the-art practice offering practice $604K. Seller is offering real estate for sale to the buyer of 33+ years of goodwill. Beautifully appointed office environment and his practice. building, located within minutes of charming downtown Capitola, known for its colorful, seaside shops and restaurants tucked into a COMING SOON: hillside along Soquel Creek. Must see this office to appreciate its Napa County GP, Marin County GP, Monterey County GP, splendor. EZ freeway access. 5 fully equipped ops. 850-900 Alameda County Pediatric Dentistry, Santa Cruz County GP, active patients (all fee-for-service). 4 doctor days/4 hygiene days & Mid-Peninsula GP per week. 2018 GR $928K with adj. net of $328K. Seasoned staff willing to stay on and Owner/Doctor willing to help for smooth transition. Asking $643K for practice. Seller owns building, it is Carroll & Company available for purchase, or to lease. 2055 Woodside Road, Suite 160 Redwood City, CA 94061 4261 CAPITOLA GP Retiring doctor offering an established DRE #00777682 practice in professional office complex built around a garden setting. Average gross $743K+ withS3OdLoDctor days and 6 hygiene days per week. Asking $562K. Mike Carroll Pamela Carroll-Gardiner Mary McEvoy Carroll

carroll.company [email protected] (650) 362-7004 (650) 362-7007 OCT. 2019 RM MATTERS

CDA JOURNAL, VOL 47, Nº10

hours of your notification of the those returning to work after an For guidance specific to your work-related injury so a claim injury or claim) differently than practice’s situation, contact TDIC’s can be set up immediately. other employees. This will eliminate Risk Management Advice Line at ■■ Provide the state-required the potential for an allegation of 800.733.0633. You may be referred to an forms to your employee after discrimination based upon filing employment attorney for matters dealing first notice of injury. a workers’ compensation claim. with personnel issues and termination. If ■■ Contact your carrier to determine ■■ Engage in an interactive discussion your employee seeks legal representation, where you can send your employee with your employee to determine if your workers’ compensation carrier for their first medical visit and you can accommodate temporary should obtain a workers’ compensation subsequent care. In the event work restrictions and provide attorney to defend your case. If you have your employee needs immediate transitional work (light duty) questions about your policy or coverage medical care, do not hesitate to while the employee heals from the options, contact your carrier directly. n call 911 or send the employee to injury. Document your discussions the nearest emergency room. in writing, as the notes could be ■■ Do not treat employees who file used as part of the claim process workers’ compensation claims (and and determination of benefits.

682 OCTOBER 2 01 9 Making your transition a reality.

Dr. Thomas Dr. Russell Dr. Rishi Jim Jay Kerri Gina Steve Jaci Kim Thinh Wagner Okihara Salwan Engel Harter McCullough Miller Caudill Hardison Ta Tran LIC #01418359 LIC #01886221 LIC #02085289 LIC #01898522 LIC #01008086 LIC #01382259 LIC #02015193 LIC #00411157 LIC #01927713 LIC #02085576 LIC #01863784 (916) 812-3255 (619) 694-7077 (909) 239-2800 (925) 330-2207 (916) 812-0500 (949) 300-0312 (707) 391-7048 (951) 314-5542 (949) 675-5578 (408) 687-5001 (949) 675-5578 45 Years in Business 38 Years in Business 10 Years in Business 46 Years in Business 36 Years in Business 35 Years in Business 30 Years in Business 30 Years in Business 26 Years in Business 16 Years in Business 11 Years in Business PRACTICE SALES • VALUATIONS/APPRAISALS • TRANSITION PLANNING • PARTNERSHIPS • MERGERS • ASSOCIATESHIPS NORTHERN CALIFORNIA SONOMA COUNTY: 2018 GR $906K. 1,000 sf. BAKERSFIELD AREA: New Listing! 5 Ops, SAN GABRIEL VALLEY: 4 Ops, Digital X- 3 Ops w/ opportunity to expand. Paperless, 4 Dr. and 4 hyg days/wk. Most specialty referred rays, 65 yrs. Goodwill. Most specialty work is CONCORD: East Bay, Digital, 3 Ops, modern/ Dentrix PM, XDR Digital sensors, and I/O cam. out. Room to grow! Real estate also available to referred out, most PPO plans are accepted. Busy attractive bldg and space, PPO, 1,200 sf, Dentrix. Selling both Practice and portion of dental bldg. purchase. 2018 GR $375K.#CA623 road with great visibility, open 4 days/wk. Nicely 2018 GR $1M+ on 34 avg. Dr. hrs/wk. #CA595 ownership. #CA594 Rare partnership appointed; excellent opportunity. #CA596 Goodwill/ BAKERSFIELD PEDO: CONTRA COSTA COUNTY: SONOMA COUNTY: Modern GP offering a opportunity at a successful 30+ yr. old Pedo SIMI VALLEY: New Listing! 6 Ops, 39 yrs. Records for only the Pedo and/or Ortho portion broad range of service. 6 Ops in 2,200 sf. space. practice with ortho and oral surgery services. Over Goodwill. Strong hyg. program. Prof. bldg. in a of Practice. 11+ yrs Goodwill. Buyer must be Seller owned facility. 2018 GR of $802K with 4 4K active patients, averaging 40 NP per month. GR great location. EagleSoft, Digital, Pano. 2018 GR within 15 miles of Contra Costa County. Asking hyg. days/wk. Dexis Digital X-ray, Dentrix PM, $2.5M+ for the past 3 yrs. #CA599 $783K. #CA617 Price is below appraised value. #CA576 I/O Camera, Laser. MOVE-IN READY, this will BURBANK: 4 Ops, est. in 1976. Modern, prof. SIMI VALLEY: New Listing! 3 Ops, 30+ yrs FREMONT: 4 Ops in approx. 1,800 sf. suite. not last! #CA564 designed suite was newly built in 2016. 2018 GR Goodwill. Older 1,100 sf. office in strip mall Dentrix PMS, Digital X-ray, Diode Laser, I/O SONOMA COUNTY: GP 1,890 sf. office, 4 Ops $751K w/ $202K Adj. Net. #CA587 shopping ctr near residential area. Most Specialty Camera. 2017 GR $446K on 3 day/wk. #CA547 2017 GR $529K on 3 Dr. days/wk. and 3.5 days/ New Listing! GP w/ great visibility, procedures referred out. 2018 GR $263K. #CA626 New Listing! Priced to sell! 40+ yrs hyg. Dexis, Dentrix, I/O Cam, laser. Real Estate COVINA: FREMONT: 4 Ops, digital X-rays. Most Specialty referred out SOUTH BAY, LOS ANGELES AREA: High Goodwill in Fremont. 2,900 sf, 9 equipped Ops available for purchase. Doctor retiring. #CA563 so there is room to grow. Bright, cheery space, income area. Prof. bldg. next to hi-end shopping in stand-alone bldg. 2018 GR $631K. #CA607 SONOMA COUNTY: Large GP. 2018 GR above word-of-mouth referrals. #CA634 ctr. 5 Ops, Digital X-rays, Laser, Long-term staff. GREATER AUBURN:1,330 sf. office w/ 3 Ops $2.8M. Stand-alone 3,000 sf. Prime Real Estate, 4 Ops, 3 Equipped, EagleSoft, 2018 GR $740K w/ $307K Adj. Net. #CA589 and 4th plumbed. Rent: $1,550/mo. Carestream 72 NP/mo. & 10 days of hyg/wk. 6 Ops, Pano X- GLENDALE: Digital, I/O Camera, and newer equipment. SOUTH BAY/TORRANCE AREA: New software. 2018 GR $474K on less than 3 days/ ray, Dexis, Cameras, Laser, Dentrix. Both Convenient prof. bldg. 2018 GR $508K w/ $249K Listing! 6 Ops in prof. bldg. 44 yrs. Goodwill. wk. Retiring seller refers out all Endo, Perio, Business & Real Estate for sale or Lease. Doctor Adj. Net. #CA575 SoftDent, Digital X-rays, I/O cam, and Laser. Ortho and surgery. #CA570 Retiring. #CA544 GLENDALE: 4 Ops, prof. bldg. Seller retiring, 14 Visiting specialists keeps procedures in-house. GREATER EL DORADO HILLS: Multi- SONOMA COUNTY: New Listing! 2018 GR yrs. Goodwill, A-dec equip, CEREC, Digital X- Strong hyg. program. 2018 GR $1M+. #CA624 doctor practice, 3,000 sf. Possible 8 Ops, 7 equip. $2 M+, 8 Ops, in a 4,600 sf. facility, 13 hyg/days rays, 35+ hrs hyg/wk. 2018 GR $499K. #CA573 I/O Cam, Digital X-rays, Digital Pan. Sellers will on 4.5 day/wk. 42 yrs. Goodwill. Doctor retiring WESTERN SAN FERNANDO VALLEY: HUNTINGTON BEACH: New Listing! 4 Ops, New Listing! 5 Ops, 4 Equipped, EagleSoft, consider working P/T. #CA578 and will work back. Paperless, Digital, hi-tech, Digital, Laser, and I/O Cam. 12+ yrs. Goodwill. modern. #CA601 50+ yrs. Goodwill. EagleSoft, 2 days hyg./wk. GREATER SACRAMENTO: 3 Op, PPO Upside potential as most specialty services referred Prof. bldg. location near a hospital. Accepts PPO practice in approx. 1,399 sf. High-end TI's and WESTERN CONTRA COSTA CO.: 1,625 sf. out. 2018 GR $356K. $141K Adj. Net. #CA613 and 3 HMO plans. 2018 GR $484K w/ $218K neighborhood, SoftDent, Carestream sensors, I/O 4 Ops, 1 plumbed. Fully digital, paperless charts, Adj. Net. #CA614 Cam. 2017 GR $506K on 4.25 day/wk. #CA543 Digital Pan, Digital X-ray, Eaglesoft PMS. 2018 LAKE ARROWHEAD/SAN BERNARDINO GR $764K, 5 days/hyg. Avg. 65 NP/mo. #CA569 MTNS: PRICE REDUCED! PPO/FFS. 6 Ops, WESTERN SAN FERNANDO VALLEY GREATER SACRAMENTO: Price Reduced! SoftDent, Dexis Digital X-rays, I/O Cam, Pano, PEDO PRACTICE: VERY MOTIVATED North Area: Modern 4 Op w/5th Open, PPO YUBA CITY AREA: 46 yrs. Goodwill, 3 Ops w/ and laser. 2018 GR $1.08M w/ $300K+ Adj. Net. SELLER! Great opportunity to purchase a Pedo practice, 1,664 sf. Higher-end TI's and 4th Open in 1,400 sf. Priced below professional Bldg. also for sale. #CA517 practice in the SF Valley. In an upscale location, neighborhood, Gendex sensor, I/O Cam, Nomad, Valuation. 2018 GR $271K. #CA580 4 Ops, EagleSoft, I/O Camera. 10+ yrs. Goodwill. Pano and Laser. 2018 GR $786K. #CA550 LOS ANGELES: New Listing! 5 Ops plus 3 chair 2017 GR $266K on 3 day/wk. #CA399 CENTRAL CALIFORNIA ortho bay. Visiting Perio and 2 hyg/days. EZ GREATER SACRAMENTO: 6 fully equipped Dental, Digital, 3DCBCT, Digital Ceph. 2018 GR SAN DIEGO Ops., Digital X-rays, pano, lasers, and Dentrix CENTRAL COAST ENDO PRACTICE: 3 over $1.7M. #CA619 software. 2018 GR $1.3M+. 7-8 hyg days/wk. Ops, Digital X-rays, Paperless, Cone Beam CT, LOS ANGELES: New Listing! 7 Ops, prof. bldg. ENCINITAS: 4 Ops. Busy retail center. Owner Retiring. #CA584 and PBS Endo Software. 2018 GR $1.1M+ w/ Remodeled 5 yrs. ago with new equipment. $635K Adj. Net. #CA489 Great location of LA. Strong hyg. program w/ 5+ GREATER STOCKTON AREA: Established days hyg./wk. 37 yrs. Goodwill. 2018 GR $983K Dentrix, Digital, Pano, and Laser. 4 hyg. days/ "All-Pedo" Limited GP Practice with 3 Ops. FRESNO PERIO/IMPLANT PRACTICE: 6 w/ $277K Adj. Net. #CA606 wk. 2018 GR $813K. #CA574 1,169 sf, attractive children-designed setting, 2 Ops, large conference room for teaching/meetings, LOS ANGELES, HANCOCK PARK: 4 Ops, NORTH COUNTY PERIO: 4 Ops, 3 Equip. Digital Sensors, Nitrous, 3 Cavitron units. 2017 20 yrs Goodwill. 2017 GR $649K & 2018 GR Newer equipment including a CT Scanner, GR $273K on avg. 3 Dr. days/wk. #CA555 $408K. 2 day/wk. Cash only office. #CA518 street frontage and signage. This office has been a Dental practice since 1928. Doctor retiring due to Digital and Dentrix. Excellent location in a well- LAKE TAHOE AREA ENDODONTIC FRESNO AREA: GP and Prosthodontic Practice illness. 2018 GR of $283K, older office equipment maintained complex. Priced to sell quickly. 2018 PRACTICE: New Listing! Endo Practice: 3 Ops, prime for a GP to purchase. 4 Ops in 1,500 sf. in a great location. #CA565 GR $269K. #CA605 3 digital sensors, Cone Beam in 1,100 sf. 2017 Digital Sensors, Pano (film), DentalMate LOS ANGELES, WEST SIDE: 4 Ops, Est. 54 SAN DIEGO COUNTY ORTHO: GR $523K on 32 avg. Dr. hrs/wk, with similar Software, attractive office bldg. and space. 2018 New Listing! Seller works out of 2 sites over 4 2018 and 2019 GR. #CA602 GR $386K. #CA588 years, SoftDent, Laser, Strong hyg. program, refers out most Specialty work. Great opportunity! 2018 day/wk. Utilizes Ortho II and Itero Element II LAKE TAHOE AREA: New Listing! 5 Ops w/ GREATER MODESTO: 4 Ops in approx. 1,400 GR $575K. #CA531 scanner. Upgrades to computer hardware. 6th Open, Operatory views of Lake Tahoe, only sf. 2018 GR $408K on 3 Dr. days/wk. Dental bldg Paperless. Over 26 yrs. Goodwill. Rare and 34 Delta Premier patients, 2,100 sf, 2018 GR must be purchased with practice. #CA546 NORTH ORANGE COUNTY: This 5 Op excellent opportunity that will sell quickly. $711K on 22 avg. Dr. hrs/wk. #CA608 practice has been open since 1965. Dentrix, digital #CA615 MADERA: GP & bldg. Centrally located, high Pano. Retiring seller will assist w/ a smooth MONTEREY PENINSULA: New Listing! visibility. 3,141 sf. 7 Ops, Dexis Digital X-rays, transition. One-story prof. bldg. 2018 GR $231K. SAN DIEGO EAST COUNTY: New Listing! Beautiful 1,130 sf. office w/ 3 Ops. 70 yrs Invisalign, Delta PPO. $968K GR w/ low Room to grow as most specialty procedures are Spring Valley, 3 Ops, strip mall location. PPO, Goodwill, 32 with present owner. Dentrix PMS, overhead. #CA566 referred out. #CA558 Digital, EZ Dental, Excellent area. #CA636 Dexis Digital X-ray, I/O Camera, Diode Laser. Modern 4 Op (room for 5th) PPO and 5 Ops, 4 equipped, in 2018 GR $528K on 4 days/wk. #CA625 MADERA: ORANGE COUNTY ENDO PRACTICE: Built SAN DIEGO PERIO: Denti-Cal practice with newer equipment, 1,800 in 2018, 6 Ops, 5 equipped, 3 Scopes, Cone Beam an excellent, bright location. Digital X-rays and NEVADA CITY/GRASS VALLEY AREA: sf. 2017 GR $233K on 2 Dr. days/wk. Bldg CT, fully digitized and paperless. GR for the past 3 Dentrix. Seller is retiring. 2017 GR $379K. 3 Ops, 55% of patients are "100% Out of facility also available for purchase. #CA542 yrs. at $1.3M+. Very low overhead. Excellent Room to grow! #CA559 Pocket". 1,700 sf, SoftDent, Film-based Pano. New opportunity. Seller retiring. #CA593 2018 GR $270K on 24 Dr. hrs/wk. #CA611 MODESTO AREA PERIO PRACTICE: OUT OF CALIFORNIA Listing! Specialty w/ 4 Ops and 5th Open in 1,600 PALM SPRINGS AREA: New Listing! 6 Ops, 5 PALO ALTO: 3 Ops, 700 sq. ft. in downtown sf. LANAP Laser and Digital Sensor. 2018 GR equip, utilizes MacPractice, Digital X-rays, and CENTRAL OAHU, HAWAII: Family-oriented leased office. Curve Hero PMS, Dexis, paperless $494K on 4 days/wk. Dental bldg. avail. #CA598 Microscope. 6 days hyg./wk. Most specialty work GP practice located in a busy shopping area. charting. 2018 GR $459K. #CA592 TRACY: New Listing! Practice established 55+ referred out. Big upside potential. No PPO or Newly refurbished, 3 Ops with new equipment, SACRAMENTO: Downtown/Midtown: Hi- yrs, central location. 1,700 sf. w/ 4 Ops, Digital X- HMO. 2018 GR $705K. $210K Adj. Net #CA612 Digital X-Rays, Upgradeable 2D Panorex, traffic, 4 Ops, under 5% Delta Premier patients. ray, Digital Pano, CAD/CAM. 2018 GR $732K. Dentrix. Excellent opportunity. Seller is PALM SPRINGS AREA MULTI-SPECIALTY: relocating. #HI112 2018 GR $607K on 30 Dr. hrs./wk. #CA590 #CA630 New Listing! 5 Ops, 1 plumbed. 2,500 sf. 27 yrs. SACRAMENTO: 3 Ops, shopping center VISALIA: New Listing! Practice and bldg. for Goodwill. Hi-end patient base. Rent is $3,600/ HONOLULU, HAWAII OMFS PRACTICE: location, Digital X-ray, move in ready. 2017 GR sale, 5 Ops, 2,000 sf. Street frontage. 2018 GR month! Dentrix, Digital, CT Scan and Gemini Dual 4 Ops. Consistent GR of $1M+ for past 3 yrs. $572K, 30 hrs./wk., 29 yrs Goodwill. #CA527 $334K. Great deal for quick sale, Refers out most Wave Laser. History of collecting $1.2M+/yr. Convenient location with ample free parking. Specialty procedures. #CA628 #CA604 PPO with no hospital affiliations. Dentrix, SAN FRANCISCO: New Listing! 2018 GR Digital Pano. Seller retiring. #HI113 $561K on reduced schedule. 4 Ops in modern SOUTHERN CALIFORNIA POMONA: New Listing! Great potential! Low 1,130 sf. 41 yrs. goodwill, 18 in current 450 rent. 4 Op practice. Only open 2 days/wk. Seller is NORTH COAST, OREGON: New Listing! Sutter location. #CA618 retiring. 2018 GR $279K. Priced to sell. #CA610 Nestled on a lake inlet minutes to the ocean. Dr BAKERSFIELD AREA: New Listing! 6 Ops, works 3 days/wk, 2 days hyg/wk. 2018 GR SANTA CRUZ COUNTY: New Listing! Well- 39 yrs. Goodwill, Dentrix, I/O Cam. 2018 GR $366K. Dr. retiring. #OR112 estab. Growing community. 1,410 sf, 4 Ops, $475K w/ $165K Adj. Net. Most specialty referred Carestream PMS, Dexis sensors, 6½ hyg days/ out, room to grow. #CA622 SOUTH COAST, OREGON: New Listing! wk. 2018 GR $1.1M+. Owner retiring. #CA609 Turnkey, 3,200 sf. 6 ops, Eaglesoft, Dexis, Pano. 2018 GR $740K. Bldg. avail. #OR113 Northern California Office www.henryscheinppt.com Southern California Office 1.800.519.3458 1.888.685.8100 Henry Schein Corporate Broker #01230466 Specialists in the Sale and Appraisal of Dental Practices Practices Serving California Dentists since 1966 How much is your practice worth?? Wanted Selling or Buying, Call PPS Today!

NORTHERN CALIFORNIA SOUTHERN CALIFORNIA (415) 899-8580 – (800) 422-2818 (714) 832-0230 – (800) 695-2732 Raymond and Edna Irving Thomas Fitterer and Dean George [email protected] [email protected] www.PPSsellsDDS.com www.PPSDental.com California DRE License 1422122 California DRE License 324962 6169 VACAVILLE Long established Delta PPO practice. 5-days of 4000 SOUTH ORANGE COUNTY - FEE FOR SERVICE High profile hygiene. 2019 trending collections of $700,000+ with Available Profits of Shopping Plaza. Can do $2 Million with energized Buyer & Associate. $250,000. Great northside location. Grosses $1.45 Million. 6168 SACRAMENTO’S CAMPUS COMMONS “Bread & butter” Delta 4001 PALM SPRINGS / LA QUINTA ~ Location, Location, Location! PPO practice averages $480,000 in collections per year. Well liked Dentist. 10+ Grossing $1.5 Million. Well equipped. High Identity. $2 Million achievable. weeks off a year. 4-days of Hygiene. 3-D Cone Beam. Integrate implants here 4003 PEDO CHINESE / HISPANIC 3,000 Charts. Established 35 years. Move as retirees in area require this service. Full Price $200,000. into your nearby office. Full Price $150,000. 6167 NORTH SANTA CLARA COUNTY - “OUT-OF-NETWORK” 4004 INLAND EMPIRE – UNION PRACTICE Can do over $1 Million. 5 ops. Perfect for Skilled Dentist who seeks strong patient relationships and wants 4005 REDLANDS HISTORIC COLLEGE CITY Long established, moved into new condo in 2015. Beautiful 6-ops. New equipment & cone beam. Seller to be insurance independent! 2019 trending $800,000+. 5-days of will transition 2 days/week at $500 per day for 2 years. Grosses $961,000 on Hygiene. Entire office has been upgraded and charting is paperless. 2.5 day week. 3.5 hygiene days. $5,000/month in HMO. Nets $400,000. Can 6166 TRI-VALLEY’S PLEASANTON 2019 trending $850,000+ in grow to $2 Million. Full Price Practice $961,000. Condo $1,100,000. collections. Averages 20 new patients per month. Attractive 4-op office, 4006 ALTA LOMA High identity shopping center. Grosses $700,000 with Digital Pan and Fabrication Center. Available Profits of $400,000. Absentee Owner. Hands-on Successor will do $1 Million. 5 ops, 3 equipped. 6165 ROSEVILLE ORTHO – “OUT-OF-NETWORK” Stanford Ranch. 4007 WEST COVINA Grosses $650,000. 2 days Hygiene. Absentee owned. Great satellite office. $455,000 invested in build-out, furnishings, 4009 IRVINE Lady DDS grossing $1 Million. 5 Ops. computers and equipment. 3-chair Bay. Digital Pan with Ceph. 51 active 4011 DIAMOND BAR Dream Million Dollar location. 5 ops equipped. Several patients and averages 3 New Patients per month. Full Price $150,000. restaurants bring in droves of customers daily. Full Price $150,000. 6164 SAN FRANCISCO BAY AREA - “OUT-OF-NETWORK” Highly 4013 ORANGE COUNTY BEACH CITY Grossed $70,000 last month. 4 ops regarded practice as evidenced by 25+ new patients per month. Collec- in 1,800 sq.ft., room for more. Seller will transition. Full Price $800,000. tions have topped $2 Million in each of the last 3-years with enviable 4014 VENTURA CTY Grossing $1.6 Million, HMO $10,000 month. Profits. Paperless. 3D Cone Beam. Great location. Seller shall work- 4015 HEMET Easy way to gross $500,000. Grossing $180,000 on 1-day. back to affect an orderly transition. Rare opportunity for that Dentist Seller must sell. Building & Practice. Full Price $110,000. seeking a Super Platform to practice their craft at the highest level. 4018 SOUTH ORANGE COUNTY Two separate practices doing approxi- 6163 LAKEPORT Attractive option to practicing in ultra-competitive mately $800,000 each. Owned by same DDS. settings in expensive housing markets. Appeal of practicing in Lakeport is 4019 $1 MIILLION NET PROFIT Opportunity of a lifetime. Phone Tom at ability live a less hectic life. Decompress, have more time for yourself. 714-832-0230. Beautiful 6-op facility with high-end technology and completely networked. 4022 VENTURA Cash and PPO. 4 days Hygiene, 4 ops. Trending $620,000+. 2018 collected $956,000 with Profits of $360,000. 2019 trending $1.1+ 4023 ORANGE Grossing $380,000 on 3-days. 1.5 days of Hygiene. Lease up in 6 months. Three 5-year options. Close to Chapman Tustin streets. Million in collections. Building optional purchase. Full Price $295,000. and 6162 REDDING Great alternative to practicing in uber-competitive markets 4021 WEST LOS ANGELES Prestigious Medical building. 39-years established. 4-ops. 4024 LA HABRA / LA MIRADA Professionally designed ffice. Next to in ultra-expensive housing communities. ng foundation evidenced by o Sto several ast ood estaurants. Cash, PPO, some Denti-Cal. HMO $3,000 per 1,500+ patients and 8-day Hygiene. Charges totaled $709,800 - f f r s of in 2018 month. Grossing $520,000+. down from 2017 which realized $779,000 Owner chooses to work less and . 4027 IRVINE - NEWPORT BEACH - SOUTH SANTA ANA - COSTA MESA takes 9-weeks off. read & butter” practice ll specialty work referred. "B . A - TUSTIN Dentist retiring. Lost Lease. Will work back. $800,000 Fee for Service. Roll-up sleeves and do $1+ Million if you choose. Patients are here. Seller BAKERSFIELD AREA Grossing $40,000 on 2 day week. 1,800 sq ft. 5 op. previously owned very busy Group Practice in Orange County beach Full Price $330,000 includes RE. community. Comparing both, he prefers his Redding practice. 2,000 sq.ft. CAPISTRANO BEACH Senior DDS. Grosses $200,000 on 16-hours. Full suite leases for $2,296/month and enjoys river views. Full Price $175,000. Price $150,000. 6158 FORTUNA Relaxed lifestyle in Humboldt County’s Banana Belt. INLAND EMPIRE DentiCal grossing near $300,000. 4 ops Rent $1,350. Full Adjacent to Ferndale. Perfect for Dentist seeking small town living. 2018 Price $195,000. Collected $395,000 with $156,000 in Profits. 2019 trending INLAND EMPIRE – UNION PRACTICE Grosses $650,000+. Nets $400,000+. 6-weeks off. Lots of work referred. Full Price $75,000. approximately $400,000 on 2.5 days. 6157 SACRAMENTO’S ELK GROVE AREA - “SOLD” 2018 collected LAGUNA WOODS Absentee owned. Grossing close to $800,000. High end area. $909,000 on Owner’s 3-day week. Successor can increase to 4-days as High identity shopping center. practice is rich in patients. 25+ new patients per month. 5-ops, digital Pan, LOS ANGELES Miracle Mile. Established 40 years. Beautiful corner suite with strong Recall, great staff. great Wilshire view. 3 ops, recently remodeled. Gross $285,000. Asking $285,000. 6152 SAN RAFAEL - “SOLD” Across from Marin Academy. 2018 ORANGE COUNTY BEACH CITY Absentee owned. Grossed $934,000 in collected $520,000. Stand-alone building optional purchase. Nearby DDS 2018. Working owner shall do $1 Million first year. who desires their own building should vertically integrate their practice REDLANDS 5 ops. Grossing $500,000. Low overhead. Long established. Female grossing $300,000. 3 ops. here and have instant $1+ Million practice in superior location. RIVERSIDE Full Price $250,000. SANTA CLARTA DDS wants to share and remain 1-day in 2 ops. 8 ops available. 6147 SAN FRANCISCO BAY AREA - “OUT-OF-NETWORK” - “SOLD” 70,000 autos pass daily. This location did almost $2 Million with previous owner 2018 collected $2.2 Million. Hygiene produced $1+ Million. $700,000+ in . VAN NUYS Starter Practice. Over 2,500 Patients. $150,000 or Make Offer. profits. Seller available for long transition. Regulatory Compliance CDA JOURNAL, VOL 47, Nº10

Practice Transition and Patient Records CDA Practice Support

dentist, “Dr. Defgh,” is retiring household hazardous waste program that vendor provides the EHR as a after 25 years of practice due to accepts waste from very small-quantity service under a cloud model, a permanent disability. Several generators. Because radiographs contain you typically would not have years earlier, she had switched silver, state law requires proper disposal received the software. Therefore from using paper charts to or recycling. Dr. Defgh must have a the EHR contract should impose Aan electronic health record system. What HIPAA business associate agreement an obligation on the vendor to is Dr. Defgh required to do with her with each of these service providers. maintain copies of all software patients’ information upon retirement? Prepare paper charts for storage by versions and to provide services The answer depends on what she organizing them by year and then to facilitate your access to the will do with the practice. Her options alphabetically by patient name. Identify software in the circumstances are to close it, to sell the practice in its a secure storage area for the charts. Dr. discussed above. You could entirety or to sell or otherwise transfer Defgh also needs to consider who will include a mechanism in your only the patient records to another dental retrieve records if needed — herself or an EHR contract to pay a reasonable practice. For purposes of this article, employee of the facility where the charts amount for these services (if Dr. Defgh is a HIPAA-covered entity. are stored. A HIPAA business associate the vendor required).”2 agreement must be obtained from any Practice Closure third party that stores the records. Practice Sale California law requires health care Determine when to end use of the Dr. Defgh is successful in finding providers ceasing operations to retain electronic health record software. Create a buyer for her practice. With regard records for at least seven years from PDF documents of each electronic to her patients’ records, she and her the date a patient was discharged or patient chart and have them stored on staff should take the following steps. last seen. With regard to the records an encrypted device. The PDF copies Notify active patients (those seen in of unemancipated minors, the records allow the dentist to email or to print the practice in the past two years) of the must be kept at least one year after and send records to patients who request dentist’s retirement and of the transition to the minor has reached the age of 18 copies. Ensure any unencrypted patient the new practice owner. Include a partially years and, in any case, not less than information is wiped from devices. completed release of records form that seven years.1 A professional liability In case of a malpractice claim, Dr. the patient can sign and return indicating carrier may recommend retaining Defgh may want to retain a secure archival authorization to release their record to the the records for a longer period. copy of the software and all documentation. new owner. Authorization is implied if a Dr. Defgh and her staff If this was not included in the original patient who did not return the release of should take these steps: software contract, she should inquire records form makes an appointment to be Notify active patients (those seen with the software company. According to seen by the practice. Patient authorization in the practice in the past two years) the Office of the National Coordinator in this regard is a requirement of of the dentist’s retirement and of the for Health Information Technology: California law and not of HIPAA. process for obtaining a copy of their “The (contract language) could Reach an agreement with the buyer on records for their new dentist. Include a be important to you in the the disposition of patient records. It is likely release of records form with the notice. defense of a medical malpractice the buyer will want to keep only the Pull paper charts of patients who claim since it may be necessary active patient records but may end up have not been seen in more than to use an old version of the EHR with all of Dr. Defgh’s records. Whoever seven years. Check for records located vendor’s software to determine has physical possession of the records is at off-site storage, if used. Separate what information could have responsible for its security and proper radiographs from paper. Shred paper been available to a health care disposal, according to California law. In or use a document destruction service. professional who reviewed a case of a malpractice claim, Dr. Defgh For disposal of radiographs, contact patient’s records at a particular should arrange for access to her records an X-ray film recycler or the local point in time. If your EHR for a recommended period of 10 years.

OCTOBER 2 0 1 9 685 OCT. 2019 REGULATORY COMPLIANCE

CDA JOURNAL, VOL 47, Nº10

Contact the electronic health record ■■ Separate the charts as described ■■ Notify patients of Dr. Defgh’s company to arrange for transfer of the previously and dispose retirement and include a release software license to the new owner. materials appropriately. of records form. The notification If the new practice owner thinks ■■ Agree to formal terms for records should include the date when the they may switch later to a different storage and retrieval, fees, access other dentist will start fulfilling electronic health record system, they by Dr. Defgh and procedures patient access to record requests. will need to ensure appropriate contract permitting the other dentist to ■■ Arrange for PDF copies of patient language is included to allow for the convert Dr. Defgh’s patients to charts as described previously. transition. Dr. Defgh should arrange for their practice. The terms should Provide an encrypted drive an archival copy of the software and include a requirement that a patient with the patient records to the information as described previously. sign an authorization releasing other dentist per agreement. their record to the other dentist. ■■ In case of a malpractice claim, Transfers Records If that dentist has no interest in arrange for access to Dr. Defgh’s Dr. Defgh is not successful in finding converting the patients to their records for a recommended period a buyer for the practice but finds a dentist practice and is simply providing of 10 years and arrange for an who is willing to store the patient records a records storage and retrieval archival copy of the electronic and to fulfill patient access to record service, a HIPAA business associate health record and documentation requests. Dr. Defgh and her staff should: agreement should be signed. as described previously.

Death or Incapacity of a Dentist If Dr. Defgh was suddenly unable to practice, California law would allow her estate or legal representative to operate the dental practice for no longer than 12 months under specified conditions, which include notifying the dental board.3 The estate or legal representative must notify patients of the dentist’s death or incapacity within 30 days of the event and provide any relevant information about the continuation of the dental practice. The dentist or dentists contracted by the estate or legal representative to operate the practice must obtain patients’ signed authorization releasing records to the dentist or dentists. n

references 1. California Health and Safety Code Section 123145. 2. Transition Issues, The Office of the National Coordinator for Health Information Technology, www.healthit.gov/sites/ default/files/playbook/pdf/ehr-contract-guide-chapter-9.pdf. Accessed July 22, 2019. 3. California Business and Professions Code Sections 1625.3 and 1625.4.

Regulatory Compliance appears monthly and features resources about laws that impact dental practices. Visit cda.org/practicesupport for more than 600 practice support resources, including practice management, employment practices, dental benefits plans and regulatory compliance.

686 OCTOBER 2 01 9

LDM_CDA_Journal_1.3_Square_LindaBrown_05_23_17.indd 1 5/24/2017 9:21:40 PM QUESTIONS MOST OFTEN ASKED BY SELLERS:

1. Can I get all cash for the sale of my practice?

2. If I decide to assist the Buyer with financing, how can I be guaranteed payment of the balance of the sales price?

3. Can I sell my practice and continue to work on a part time basis?

4. How can I most successfully transfer my patients to the new dentist?

5. What if I have some reservation about a prospective Buyer of my practice?

6. How can I be certain my Broker will demonstrate absolute discretion in handling the transaction in all aspects, including dealing with personnel and patients?

7. What are the tax and legal ramifications when a dental practice is sold? QUESTIONS MOST OFTEN ASKED BY BUYERS:

1. Can I afford to buy a dental practice?

LEE SKARIN 2. Can I afford not to buy a dental practice? INC. & ASSOCIATES

3. What are ALL of the benefits of owning a practice?

4. What kinds of assets will help me qualify for financing the purchase of a practice?

5. Is it possible to purchase a practice without a personal cash investment?

6. What kinds of things should a Buyer consider when evaluating a practice? 7. What are the tax consequences for the Buyer when purchasing a practice? Offices: Lee Skarin & Associates have been successfully assisting Sellers and Buyers 805.777.7707 of Dental Practices for nearly 30 years in providing the answers to these and other questions that have been of concern to Dentists. 818.991.6552 Call at anytime for a no obligation response to any or all of your questions Visit our website for current listings: www.LeeSkarinandAssociates.com 800.752.7461 CA DRE #00863149 Timothy Giroux, DDS John M. Cahill, MBA Edmond P. Cahill, JD Your Life’s Work Jon B. Noble, MBA Mona Chang, DDS Comes Down To BAY AREA BAY AREA CONTINUED BAY AREA CONTINUED NORTHERN CALIFORNIA CONTINUED

This Decision AC-989 SAN FRANCISCO (Facility): Busy Retail Shopping CC-960 SONOMA: Great location in one-of-a-kind set- DN-1031 CUPERTINO: This remarkable practice awaits only your talent and skill! HG-815 TRUCKEE AREA: Busy, productive practice with 3 days of hygiene! ~1000 Plaza w/ major anchor tenants! 3 ops $125k ting! 950 sf w/ 3 ops. $385k/ Real Estate Available 1500sf w 3 ops + 1 add’l. Reduced $1.1M sf w/ 3 ops $165k/ Real Estate $437k What separates us from AC-1059 DALY CITY: Amazing practice w/ seasoned staff $350k DN-1032 PLEASANTON Facility: The perfect place to live, practice & raise a HG-983 GRASS VALLEY: Newly remodeled office in highly desirable neighborhood! in highly desirable neighborhood. 1500 sf w/ 4 ops CC-979 NOVATO: Seller Retiring. 803 sf w/ 3 ops near family! 1400sf w/4ops. Includes CTScan! $185k ~1250 sf w/ 3 ops. Reduced Price $195k/Real Estate Available other brokerage firms? $345k downtown and Old Town Novato. $195K (Real Estate DN-1041 SAN JOSE: This stunning practice is an excellent opportunity for new HG-987 LAKE TAHOE AREA: State-of-the-Art Practice located in picturesque

AG-871 SAN FRANCISCO: Seller Motivated! ~600 sf w/ 2 $215k) grads! 1207sf w 2ops + 1 add’l. $195k mountain setting! ~ 3,400 sf w/ 6 Ops CALL FOR DETAILS Western Practice Sales is locally ops Price Reduced $65k CC-1017 VACAVILLE: Maximize your work days and DN-1003 PLEASANTON Facility: This is an excellent opportunity for a graduate or HN-618 SIERRA FOOTHILLS: Seller Retiring! Huge opportunity for growth by in- owned by dentists and has been AG-944 SAN FRANCISCO: An opportunity like this does watch your production increase! ~ 1500 sf w/ 4 ops a dentist seeking a Satellite location. 1000sf w/ 3ops. $68k creasing office hours! 750 sf w/ 2 ops $65k not come along very often! ~980 sf w/ 3 ops Reduced $130k DN-1046 SANTA CRUZ AREA: Opportunities like this does not come along, HN-879 SONORA: Great Cash-Flow for Only 3 Days a Week! 2950 sf w/ 3 ops proudly serving dentists in $575k CC-1020 SANTA ROSA: Cash Flow of over $270k. except once in a lifetime! Office 2050 sf w/ 5 ops. Total sq ft 3880. $595k / Reduced Price: $265k California for over 45 years. Our AG-945 SOUTH SAN FRANCISCO: Be a part of this vi- Unique FFS Practice. 1320 sf w/ 4 ops. $450k Real Estate: $1.1mil HG-934 GRASS VALLEY: Underworked PT base should support larger production personal attention to our sellers brant, diverse population. ~1800 sf w/ 4 ops $495k CC-1030 SANTA ROSA: Condo office in modern bldg numbers! ~1200 sf w/ 3 Ops Reduced $168,750/Real Estate Available AG-990 SAN FRANCISCO: Build the practice of your w/ ample parking & adjoining Ortho practice! 1683 sf NORTHERN CALIFORNIA HN-999 CALAVERAS Co. (Facility/Real Estate): 1,500 sf w/ 2 equipped Ops + 1 fully and reputation of integrity and dreams! ~850 sf w/ 3 ops $228k w 5 ops $325k plumbed & 3 partially plumbed.$ 500k honesty has made us Northern AG-993 WEST PORTAL AREA: Desirable area w/ easy CC-1049 SANTA ROSA: Fully Remodeled, Amazing EC-1005 YOLO CO: Highly Successful w/ Great Reputation in the Community! HN-991 PLACERVILLE: Quality, conservative and compassionate practice! Will California’s Preferred Dental commute to downtown San Francisco. ~1000sf w/ 3 Location. 2000 sf w/ 5 ops $685k Real Estate Also 1239 sf w/ 3 fully equipped ops $720k consider work back. 1,654 + 473 sf w 5 ops. $675k Practice Broker. ops Reduced Price: $410k Available EG-910 MIDTOWN SACRAMENTO: A thriving practice does not come along AG-994 SAN FRANCISCO: Highly profitable with net CG-616 NAPA COUNTY: State-of-the-Art office! ~850 very often! ~1107 sf w/ 2 + 1 add’l. Reduced $210k CENTRAL VALLEY & SOUTHERN CALIFORNIA

profit over $400k! ~850 sf w/ 3 Ops $825K sf w/ 2 Ops. Price Reduced – Seller Motivated $250k EG-968 SACRAMENTO: Desirable, mid-town neighborhood, w/ ample parking

Our extensive buyer BC-741 DANVILLE (FACILITY): Move in Ready! ~ 1600 CG-995 VALLEJO: Live, play and practice here where in garage! ~1527 sf w/ 5 Ops. Reduced $480k IC-975 MODESTO: Established 33 years. 1,100 sf w/ 3 ops $225k sf w/ 3 ops. PRICED TO SELL! $10k your lifestyle can’t be beat! ~2035 sf w/ 7 ops EG-972 ELK GROVE: Prime location! Real Estate available to purchase in the IG-881 TURLOCK: Long established has unsurpassed quality care. ~3500 sf w/ 10 database BC-926 ANTIOCH: Long established, well respected $1.175M future! ~ 3500 sf w/ 8 ops+. Reduced $495k Ops (shared). Reduced: $295k allows us to offer you… office. 1866 sf w/ 5 ops $495k CG-1037 SONOMA COUNTY: Your lifestyle and prac- EG-1012 EAST SACRAMENTO: A practice like this one does not come available IG-1007 GREATER MODESTO AREA: Combines a quality learning environment BC-949 ALBANY: Desirable commercial/residential tice will indeed be the envy of many dentists! ~1310 very often! ~ 2900 sf w/ 8 ops. $2.5M with relaxed rural living. ~3000sf w/ 6 ops. $645k Better Exposure area. Medical Prof Bldg w/ good frontage. 3200sf w/ sf w/4 ops $395k EG-1016 LINCOLN: Look no further than this growing community to spring- IG-1009 TRACY: This opportunity is waiting for you to sink your roots down and 4 ops $695k Real Estate: $1.8 CG-1048 SONOMA: This highly successful family- board into your success! ~1800 sf w/ 4 Ops Reduced $570k invest your future here! ~1200sf w/ 4 ops. $745k Better Fit BC-1010 ANTIOCH: Amazing Opportunity in Health oriented practice has it ALL! ~1500 sf w/ 4 ops $650k EG-1039 EL DORADO HILLS VICINITY: The ideal opportunity to practice in this IN-917 MERCED AREA: Well established practice with a stable, loyal patient Prof. Complex 2118 sf w/ 2 equipped ops + 3 add’l CN-911 SANTA ROSA: “Quality Care & Patient well- community! ~1100 sf w/ 4 Ops. $350k base! 1300 sf w/ 3 Ops. Reduced! $295k Better Price! $250k being FIRST”. 2250 sf w/4 ops + 1add’l. Now: $520k EG-1061 SOUTH AUBURN VICINITY: Come live, play and practice in the heart of JC-811 FRESNO COUNTY: Seller willing to consider Associateship for qualified DDS BC-1022 OAKLAND: “Pill Hill” Area adjacent to hospi- DG-862 MID-PENINSULA: Rare gem with up to 7 opera- this pristine town! ~1100 sf w/ 4 Ops. $350k w. intention to Buy In! 3,000 sf w/ 6 ops $350k tal! 1064 sf & 2 ops. Plumbed for 1 add’l $150k tories in the Bay Area! ~2274 sf w/ 6ops + 1 add’l. EN-1051 SACRAMENTO: Location, Accessibility and Quality Relationships! JC-823 LOS BANOS: Heavy emphasis on hygiene. 1000 sf w/ 3 ops $80k BC-1056 SAN RAMON (Facility): Move-in ready! Well $475k 1,671sf w/ 5ops. $395k JC-1054 VISALIA: Practice AND REAL ESTATE! Prof Bldg on major thoroughfare. maintained prof complex. 1698 sf w/ 4 ops $100k DG-936 SUNNYVALE: Hesitate and you may lose out on EN-1052 EAST SACRAMENTO: Remarkable, long-established opportunity, loaded 2,260 sf w/ 6 ops $275k/ Real Estate $517k BG-981 BERKELEY: Long established, family-oriented this opportunity of a lifetime! ~1000 sf w/ 3 ops. $495K w/ goodwill! 1100 sf w/ 4 ops. $950k KG-921 SANTA MARIA: Live and practice in this desirable collegiate coastal com- practice. ~1100 sf w/ 3 Ops $345k/ Real Estate $499k DG-986 CAMPBELL: The ~988 sf w/ 3 ops Seller Moti- EN-1055 ROCKLIN Facility: Build your own success here in this family-oriented munity! ~930 sf w/ 3 ops Seller Motivated $285k BG-1025 WALNUT CREEK: You won’t find a more out- vated $288k community! 1650 sf w/ 4 ops +1 add’l. $95k standing opportunity than this extraordinary practice! DG-1006 MONTEREY AREA: This practice is one which FC-650 FORT BRAGG: Family-oriented practice. 5 ops in 2000 sf $350k for the SPECIALTY PRACTICES ~2138 sf w/ 6 ops. $750k Real Estate: $995k every dentist aspires to! ~3400 sf w/ 8 ops $1.395M Practice & $400k for the Real Estate BN-952 BERKELEY: Don’t hesitate on this incredible DG-1009 CARMEL: Amazing fee-for-service practice w/ FG-841 ARCATA: Great demographics w/ very little competition! ~1114 sf w/3 BC-784 CENTRAL CONTRA COSTA CO Perio: Seasoned Staff. Office runs like well- opportunity! ~835 sf w/ 3 Ops. Seller Motivated $200k no contracts! ~1150 sf w/ 4 ops $625K ops Reduced Price: $200k/ Real Estate Available oiled machine! 3 ops $295k BN-1023 RICHMOND: This is a rich opportunity for the DG-1014 MONTEREY: Don’t miss your opportunity to FN-961 EUREKA: Where the quality of life can’t be beat! 1400sf w. 4 ops. BG-843 WALNUT CREEK Perio: Priced at 50% of collections! ~1085 sf w/ 4 ops astute dentist! 1450sf w/2 ops + 2 add’l. $50k/ Real live and practice in beautiful Monterey! ~1125 sf w/ Practice Reduced: $395k/ Real Estate Available $395k! $390k Estate $750k 4 Ops. $875k FN-855 NO. HUMBOLDT: Seller relocating! Long-established, 100% FFS practice! BG-1024 WALNUT CREEK Prosth: Stellar reputation for providing the highest level BN-1038 BERKELEY: A perfect opportunity to own a DG-1034 BELMONT: Med Prof Bldg on bustling com- 1600 sf w/ 3ops + 1 add’l. $190k/ Real Estate Available of treatment! ~2138 sf w/ 6 ops. $750k Real Estate: $995k practice in one the Bay Area’s most popular cities! mercial corridor. ~2000 sf w/ 5 ops $425k GN-953 CHICO: Established for 55 years and the seller is passing their goodwill BN-998 WALNUT CREEK/SAN RAMON AREA Ortho: Looking for your dream Or- 1000sf w/ 3ops. $385k DG-1035 LOS GATOS: Over 40 years Goodwill in this on to you! 1067sf w/ 3ops. Now Only $275k! thodontic practice! 1450 sf w/ 5 Open bays/Chairs.$ 1.150M BN-1045 CONCORD: Imagine owning a highly success- charming community! ~1010 sf w/ 4 ops. $790k GN-924 TEHAMA COUNTY: Don’t miss this ideal opportunity! 3000 sf w/ 6 ops. DC-835 TRI-VALLEY Perio: Collections over $1.2M. 2,100 sf $800k ful, family-oriented practice! 1150sf w/ 3 ops. $165k DG-1040 SUNNYVALE: Don’t hesitate on this remark- Practice $495k / Real Estate $455k DN-1044 FOSTER CITY Pedo: Shared Space Situation. Conveniently located Call or email today for a free CC-846 SAN RAFAEL: Prof/Retail Building Complex. 3 ops able opportunity! ~3477 sf w/ 6 ops $1.085M Real GN-988 YUBA CITY: Excellent Merger Opportunity! Location and Lifestyle! 1,600 sf within walking distance of major corporations. 830sf w/ 3 ops. $195k copy of Dr Giroux’s book 640 sf Collections $433k in 2017 $275k Estate Available w/ 3 ops. $100k GG-940 NORTH OF SACRAMENTO Pedo: Practice is on track to collect more than CC-927 SAN RAFAEL: Build the practice of your dreams DG-1042 MOUNTAIN VIEW: Amazing opportunity HG-1053 GRASS VALLEY: Well-established practice of 40+ years, known for its $1,000,000 in revenues this year! ~4300 sf w/ 5 ops. Reduced $555k by increasing this 2-day work week! 800 sf w/ 3 ops providing quality, high-end dentistry! ~ 890 sf w/ 3 quality dentistry! ~1200 sf w/ 3 ops $420K JG-757 VISALIA Perio: Incredible Giveaway at this price! Collections over Top Ten Issues for $175k Ops CALL FOR DETAILS $800k! ~2000 sf w/ 5 ops Steal at $150k Dentists Contemplating Retirement in Ten Years or Less 800.641.4179 [email protected] “ASK THE BROKER” can now be found at WWW.WESTERNPRACTICESALES.COM Timothy Giroux, DDS John M. Cahill, MBA Edmond P. Cahill, JD Your Life’s Work Jon B. Noble, MBA Mona Chang, DDS Comes Down To BAY AREA BAY AREA CONTINUED BAY AREA CONTINUED NORTHERN CALIFORNIA CONTINUED

This Decision AC-989 SAN FRANCISCO (Facility): Busy Retail Shopping CC-960 SONOMA: Great location in one-of-a-kind set- DN-1031 CUPERTINO: This remarkable practice awaits only your talent and skill! HG-815 TRUCKEE AREA: Busy, productive practice with 3 days of hygiene! ~1000 Plaza w/ major anchor tenants! 3 ops $125k ting! 950 sf w/ 3 ops. $385k/ Real Estate Available 1500sf w 3 ops + 1 add’l. Reduced $1.1M sf w/ 3 ops $165k/ Real Estate $437k What separates us from AC-1059 DALY CITY: Amazing practice w/ seasoned staff $350k DN-1032 PLEASANTON Facility: The perfect place to live, practice & raise a HG-983 GRASS VALLEY: Newly remodeled office in highly desirable neighborhood! in highly desirable neighborhood. 1500 sf w/ 4 ops CC-979 NOVATO: Seller Retiring. 803 sf w/ 3 ops near family! 1400sf w/4ops. Includes CTScan! $185k ~1250 sf w/ 3 ops. Reduced Price $195k/Real Estate Available other brokerage firms? $345k downtown and Old Town Novato. $195K (Real Estate DN-1041 SAN JOSE: This stunning practice is an excellent opportunity for new HG-987 LAKE TAHOE AREA: State-of-the-Art Practice located in picturesque

AG-871 SAN FRANCISCO: Seller Motivated! ~600 sf w/ 2 $215k) grads! 1207sf w 2ops + 1 add’l. $195k mountain setting! ~ 3,400 sf w/ 6 Ops CALL FOR DETAILS Western Practice Sales is locally ops Price Reduced $65k CC-1017 VACAVILLE: Maximize your work days and DN-1003 PLEASANTON Facility: This is an excellent opportunity for a graduate or HN-618 SIERRA FOOTHILLS: Seller Retiring! Huge opportunity for growth by in- owned by dentists and has been AG-944 SAN FRANCISCO: An opportunity like this does watch your production increase! ~ 1500 sf w/ 4 ops a dentist seeking a Satellite location. 1000sf w/ 3ops. $68k creasing office hours! 750 sf w/ 2 ops $65k not come along very often! ~980 sf w/ 3 ops Reduced $130k DN-1046 SANTA CRUZ AREA: Opportunities like this does not come along, HN-879 SONORA: Great Cash-Flow for Only 3 Days a Week! 2950 sf w/ 3 ops proudly serving dentists in $575k CC-1020 SANTA ROSA: Cash Flow of over $270k. except once in a lifetime! Office 2050 sf w/ 5 ops. Total sq ft 3880. $595k / Reduced Price: $265k California for over 45 years. Our AG-945 SOUTH SAN FRANCISCO: Be a part of this vi- Unique FFS Practice. 1320 sf w/ 4 ops. $450k Real Estate: $1.1mil HG-934 GRASS VALLEY: Underworked PT base should support larger production personal attention to our sellers brant, diverse population. ~1800 sf w/ 4 ops $495k CC-1030 SANTA ROSA: Condo office in modern bldg numbers! ~1200 sf w/ 3 Ops Reduced $168,750/Real Estate Available AG-990 SAN FRANCISCO: Build the practice of your w/ ample parking & adjoining Ortho practice! 1683 sf NORTHERN CALIFORNIA HN-999 CALAVERAS Co. (Facility/Real Estate): 1,500 sf w/ 2 equipped Ops + 1 fully and reputation of integrity and dreams! ~850 sf w/ 3 ops $228k w 5 ops $325k plumbed & 3 partially plumbed.$ 500k honesty has made us Northern AG-993 WEST PORTAL AREA: Desirable area w/ easy CC-1049 SANTA ROSA: Fully Remodeled, Amazing EC-1005 YOLO CO: Highly Successful w/ Great Reputation in the Community! HN-991 PLACERVILLE: Quality, conservative and compassionate practice! Will California’s Preferred Dental commute to downtown San Francisco. ~1000sf w/ 3 Location. 2000 sf w/ 5 ops $685k Real Estate Also 1239 sf w/ 3 fully equipped ops $720k consider work back. 1,654 + 473 sf w 5 ops. $675k Practice Broker. ops Reduced Price: $410k Available EG-910 MIDTOWN SACRAMENTO: A thriving practice does not come along AG-994 SAN FRANCISCO: Highly profitable with net CG-616 NAPA COUNTY: State-of-the-Art office! ~850 very often! ~1107 sf w/ 2 + 1 add’l. Reduced $210k CENTRAL VALLEY & SOUTHERN CALIFORNIA

profit over $400k! ~850 sf w/ 3 Ops $825K sf w/ 2 Ops. Price Reduced – Seller Motivated $250k EG-968 SACRAMENTO: Desirable, mid-town neighborhood, w/ ample parking

Our extensive buyer BC-741 DANVILLE (FACILITY): Move in Ready! ~ 1600 CG-995 VALLEJO: Live, play and practice here where in garage! ~1527 sf w/ 5 Ops. Reduced $480k IC-975 MODESTO: Established 33 years. 1,100 sf w/ 3 ops $225k sf w/ 3 ops. PRICED TO SELL! $10k your lifestyle can’t be beat! ~2035 sf w/ 7 ops EG-972 ELK GROVE: Prime location! Real Estate available to purchase in the IG-881 TURLOCK: Long established has unsurpassed quality care. ~3500 sf w/ 10 database BC-926 ANTIOCH: Long established, well respected $1.175M future! ~ 3500 sf w/ 8 ops+. Reduced $495k Ops (shared). Reduced: $295k allows us to offer you… office. 1866 sf w/ 5 ops $495k CG-1037 SONOMA COUNTY: Your lifestyle and prac- EG-1012 EAST SACRAMENTO: A practice like this one does not come available IG-1007 GREATER MODESTO AREA: Combines a quality learning environment BC-949 ALBANY: Desirable commercial/residential tice will indeed be the envy of many dentists! ~1310 very often! ~ 2900 sf w/ 8 ops. $2.5M with relaxed rural living. ~3000sf w/ 6 ops. $645k Better Exposure area. Medical Prof Bldg w/ good frontage. 3200sf w/ sf w/4 ops $395k EG-1016 LINCOLN: Look no further than this growing community to spring- IG-1009 TRACY: This opportunity is waiting for you to sink your roots down and 4 ops $695k Real Estate: $1.8 CG-1048 SONOMA: This highly successful family- board into your success! ~1800 sf w/ 4 Ops Reduced $570k invest your future here! ~1200sf w/ 4 ops. $745k Better Fit BC-1010 ANTIOCH: Amazing Opportunity in Health oriented practice has it ALL! ~1500 sf w/ 4 ops $650k EG-1039 EL DORADO HILLS VICINITY: The ideal opportunity to practice in this IN-917 MERCED AREA: Well established practice with a stable, loyal patient Prof. Complex 2118 sf w/ 2 equipped ops + 3 add’l CN-911 SANTA ROSA: “Quality Care & Patient well- community! ~1100 sf w/ 4 Ops. $350k base! 1300 sf w/ 3 Ops. Reduced! $295k Better Price! $250k being FIRST”. 2250 sf w/4 ops + 1add’l. Now: $520k EG-1061 SOUTH AUBURN VICINITY: Come live, play and practice in the heart of JC-811 FRESNO COUNTY: Seller willing to consider Associateship for qualified DDS BC-1022 OAKLAND: “Pill Hill” Area adjacent to hospi- DG-862 MID-PENINSULA: Rare gem with up to 7 opera- this pristine town! ~1100 sf w/ 4 Ops. $350k w. intention to Buy In! 3,000 sf w/ 6 ops $350k tal! 1064 sf & 2 ops. Plumbed for 1 add’l $150k tories in the Bay Area! ~2274 sf w/ 6ops + 1 add’l. EN-1051 SACRAMENTO: Location, Accessibility and Quality Relationships! JC-823 LOS BANOS: Heavy emphasis on hygiene. 1000 sf w/ 3 ops $80k BC-1056 SAN RAMON (Facility): Move-in ready! Well $475k 1,671sf w/ 5ops. $395k JC-1054 VISALIA: Practice AND REAL ESTATE! Prof Bldg on major thoroughfare. maintained prof complex. 1698 sf w/ 4 ops $100k DG-936 SUNNYVALE: Hesitate and you may lose out on EN-1052 EAST SACRAMENTO: Remarkable, long-established opportunity, loaded 2,260 sf w/ 6 ops $275k/ Real Estate $517k BG-981 BERKELEY: Long established, family-oriented this opportunity of a lifetime! ~1000 sf w/ 3 ops. $495K w/ goodwill! 1100 sf w/ 4 ops. $950k KG-921 SANTA MARIA: Live and practice in this desirable collegiate coastal com- practice. ~1100 sf w/ 3 Ops $345k/ Real Estate $499k DG-986 CAMPBELL: The ~988 sf w/ 3 ops Seller Moti- EN-1055 ROCKLIN Facility: Build your own success here in this family-oriented munity! ~930 sf w/ 3 ops Seller Motivated $285k BG-1025 WALNUT CREEK: You won’t find a more out- vated $288k community! 1650 sf w/ 4 ops +1 add’l. $95k standing opportunity than this extraordinary practice! DG-1006 MONTEREY AREA: This practice is one which FC-650 FORT BRAGG: Family-oriented practice. 5 ops in 2000 sf $350k for the SPECIALTY PRACTICES ~2138 sf w/ 6 ops. $750k Real Estate: $995k every dentist aspires to! ~3400 sf w/ 8 ops $1.395M Practice & $400k for the Real Estate BN-952 BERKELEY: Don’t hesitate on this incredible DG-1009 CARMEL: Amazing fee-for-service practice w/ FG-841 ARCATA: Great demographics w/ very little competition! ~1114 sf w/3 BC-784 CENTRAL CONTRA COSTA CO Perio: Seasoned Staff. Office runs like well- opportunity! ~835 sf w/ 3 Ops. Seller Motivated $200k no contracts! ~1150 sf w/ 4 ops $625K ops Reduced Price: $200k/ Real Estate Available oiled machine! 3 ops $295k BN-1023 RICHMOND: This is a rich opportunity for the DG-1014 MONTEREY: Don’t miss your opportunity to FN-961 EUREKA: Where the quality of life can’t be beat! 1400sf w. 4 ops. BG-843 WALNUT CREEK Perio: Priced at 50% of collections! ~1085 sf w/ 4 ops astute dentist! 1450sf w/2 ops + 2 add’l. $50k/ Real live and practice in beautiful Monterey! ~1125 sf w/ Practice Reduced: $395k/ Real Estate Available $395k! $390k Estate $750k 4 Ops. $875k FN-855 NO. HUMBOLDT: Seller relocating! Long-established, 100% FFS practice! BG-1024 WALNUT CREEK Prosth: Stellar reputation for providing the highest level BN-1038 BERKELEY: A perfect opportunity to own a DG-1034 BELMONT: Med Prof Bldg on bustling com- 1600 sf w/ 3ops + 1 add’l. $190k/ Real Estate Available of treatment! ~2138 sf w/ 6 ops. $750k Real Estate: $995k practice in one the Bay Area’s most popular cities! mercial corridor. ~2000 sf w/ 5 ops $425k GN-953 CHICO: Established for 55 years and the seller is passing their goodwill BN-998 WALNUT CREEK/SAN RAMON AREA Ortho: Looking for your dream Or- 1000sf w/ 3ops. $385k DG-1035 LOS GATOS: Over 40 years Goodwill in this on to you! 1067sf w/ 3ops. Now Only $275k! thodontic practice! 1450 sf w/ 5 Open bays/Chairs.$ 1.150M BN-1045 CONCORD: Imagine owning a highly success- charming community! ~1010 sf w/ 4 ops. $790k GN-924 TEHAMA COUNTY: Don’t miss this ideal opportunity! 3000 sf w/ 6 ops. DC-835 TRI-VALLEY Perio: Collections over $1.2M. 2,100 sf $800k ful, family-oriented practice! 1150sf w/ 3 ops. $165k DG-1040 SUNNYVALE: Don’t hesitate on this remark- Practice $495k / Real Estate $455k DN-1044 FOSTER CITY Pedo: Shared Space Situation. Conveniently located Call or email today for a free CC-846 SAN RAFAEL: Prof/Retail Building Complex. 3 ops able opportunity! ~3477 sf w/ 6 ops $1.085M Real GN-988 YUBA CITY: Excellent Merger Opportunity! Location and Lifestyle! 1,600 sf within walking distance of major corporations. 830sf w/ 3 ops. $195k copy of Dr Giroux’s book 640 sf Collections $433k in 2017 $275k Estate Available w/ 3 ops. $100k GG-940 NORTH OF SACRAMENTO Pedo: Practice is on track to collect more than CC-927 SAN RAFAEL: Build the practice of your dreams DG-1042 MOUNTAIN VIEW: Amazing opportunity HG-1053 GRASS VALLEY: Well-established practice of 40+ years, known for its $1,000,000 in revenues this year! ~4300 sf w/ 5 ops. Reduced $555k by increasing this 2-day work week! 800 sf w/ 3 ops providing quality, high-end dentistry! ~ 890 sf w/ 3 quality dentistry! ~1200 sf w/ 3 ops $420K JG-757 VISALIA Perio: Incredible Giveaway at this price! Collections over Top Ten Issues for $175k Ops CALL FOR DETAILS $800k! ~2000 sf w/ 5 ops Steal at $150k Dentists Contemplating Retirement in Ten Years or Less 800.641.4179 [email protected] “ASK THE BROKER” can now be found at WWW.WESTERNPRACTICESALES.COM Tech Trends CDA JOURNAL, VOL 47, Nº10

A look into the latest dental and general technology on the market

Cash App (Free, Square Inc.) IvoSmile (Free, Ivoclar Vivadent) Cash App, from the makers of Square and available for iOS and Augmented reality (AR) is the technology that allows computers to Android, makes it easy to send and receive money from people, overlay information onto the real world. Since 2013, AR has seen make purchases at merchants and even buy cryptocurrency. an explosion in use, and now companies like Amazon, Google and Disney have integrated it into multiple facets of their products. Cash App is a service that requires a verified mobile phone number Without leaving their homes, consumers can see whether a new and/or email address to start. The account setup process is fast, couch will fit in their living rooms, check out the latest fashions and once the process is complete, users assign themselves a unique without having to try them on and test the latest gadgets without the identifier called a $Cashtag to identify themselves to other Cash gadgets themselves being physically present. Dentistry has taken App users. The home screen is a simple interface to send and notice of AR, and Ivoclar Vivadent has been a forerunner of AR’s receive money to and from peers. Users enter a dollar amount and clinical usage. This review focuses on the iPhone deployment of tap “Request” or “Pay,” specify a person using their name, phone IvoSmile, which is a demo version of the application and does not number, email address or $Cashtag along with its purpose and fully reflect capabilities of the subscription-based iPad version of the then complete the transaction. With Bluetooth and app permissions application. An iPhone X was utilized for this review. enabled on mobile devices, users can also search for Cash App users close by. Funds are deposited or withdrawn from a Cash Card Released in 2018, IvoSmile for iPhone demonstrates the capabilities account, easily accessible using a button at the top of the home of its AR. Opening the application activates the front-facing camera screen. The Cash Card can be funded from a bank account debit and superimposes an outline of a head. The screen is divided into a card at no charge. Users can also request a physical Cash App debit left half and right half: The left half is labeled “Before” and the right card to be sent to their mailing address, which draws from available half is labeled “After.” When a user’s smiling face is maneuvered funds in their Cash Card account. The Cash Card can also be added into the outline, IvoSmile replaces the user’s maxillary teeth with to Apple Pay Wallet, making it easy to make mobile payments at two possible sets of Ivoclar teeth that can be selected. Additionally, merchants. Cash App payments can also be made using a linked users can activate a slider to adjust their tooth shade. Pressing the credit card, which will incur a 3 percent additional charge. pause button freezes the frame so that the image can be captured and shared. The application is easy to use and, for a demo Unique to Cash App is the ability to easily purchase Bitcoin. From deployment, is remarkably accurate and robust in its AR capabilities. the Cash Card account view, users can select Bitcoin and see its Ultimately, IvoSmile for iPhone is a novelty, albeit one that succinctly current market price and year-to-date historical data. Users can then demonstrates the commitment to AR that Ivoclar Vivadent has made directly purchase or sell Bitcoin with available funds in their Cash and generates excitement for the potential of the subscription-based App. There are no fees to buy or sell Bitcoin. Additionally, there are iPad version. no fees to receive or send money to Cash App peers with available Cash Card account funds. Annual reporting forms for tax purposes — Alexander Lee, DMD from Bitcoin sold are available through the Cash App. Easy-to-use, cross-platform and versatile in function, Cash App Would you like to write about technology? greatly reduces the need to carry physical cash in many cases. Dentists interested in contributing to this section should contact Because its primary function is a peer-to-peer payments service, all Andrea LaMattina, CDE, at [email protected]. users must interact directly with the Cash App to take advantage of its features. Otherwise, users may still need to carry cash, which is still accepted everywhere. — Hubert Chan, DDS

690 OCTOBER 2 01 9 The Art and Science of Dentistry

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Like us @cdadentists Follow us Anaheim #cdaANA San Francisco #cdaSF @cdadentists May 14–16, 2020 Sept. 10–12, 2020 Connect with us California Dental Association May 13–15, 2021 Sept. 9–11, 2021 Follow us @cdadentists CheerfulMY SMILE IS

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Augustina, from China—a data analyst, painter, and kickboxer—travels the world with a smile. Opalescence® Boost® in-office whitening quickly whitens her smile to keep up with her jet-setting lifestyle. A brighter, whiter smile will help each of your patients live their best life. That’s the power of a smile. Find out more at ultradent.com/mysmileispowerful.

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