Fabricating complete with CAD/CAM technology

Luis Infante, DDS,a Burak Yilmaz, DDS, PhD,b Edwin McGlumphy, DDS, MS,c and Israel Finger, DDS, MSd School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, La; Division of Restorative and Prosthetic Dentistry, The Ohio State University, College of Dentistry, Columbus, Ohio

Conventional complete denture prosthetics require several appointments to register the maxillomandibular relationship and evaluate the esthetics. The fabrication of milled complete dental prostheses with digital scanning technology may decrease the number of appointments. The step-by-step method necessary to obtain impressions, maxillomandibular relation records, and anterior tooth position with an anatomic measuring device is described. The technique allows the generation of a virtual denture, which is milled to exact specifications without the use of conventional stone casts, flasking, or processing techniques. (J Prosthet Dent 2014;-:---)

Present-day advances have led to restoration with the CAM portion of software that allowed the milling of the incorporation of computer-aided the system. the tooth sockets in the denture base design/computer-aided manufacturing In 2007, Quaas et al6 studied the according to the desired arrangement. (CAD/CAM) technology into the measurement uncertainty and the 3- The use of computer-generated design and fabrication of dental res- dimensional accuracy of a mechanical dentures is changing the procedures torations, including complete den- digitizing system and concluded that for denture fabrication. CAD/CAM tures. Different systems for making the measurement uncertainty for the technology differs from the conven- impressions and fabricating casts of a system was low and the precision was tional method in that the laboratory patient’s dental structures have been high. However, they discouraged the work is simplified and fewer appoint- introduced,1,2 some of which also application of this method for the ments are needed.10 Recently, Bidra11 allow for the production of specific digitization of flexible impression ma- reported the use of CAD/CAM tech- restorations in the laboratory, in the terials because the physical contact of nology for the fabrication of mandib- dental office, or at a centralized pro- the probe with the soft material might ular implant-retained overdentures in duction center.3-5 lead to deformation and increased in- only 2 clinical appointments. This The information for the develop- accuracy. In 2012, Goodacre et al2 report describes a technique to fabri- ment of a CAD/CAM cast or restora- proposed a technique to obtain maxil- cate a complete dental with tion can be acquired extraorally from lary and mandibular definitive impres- CAD/CAM technology. The technique an impression or from a cast of sions of the edentulous arches so these presented uses a standard clinical pro- the object or intraorally by directly could be scanned and data acquired to cedure to fabricate dentures for a pa- recording the structures intraorally. mill denture bases with CAD/CAM tient with existing dentures in only 2 Different systems use different tools to technology. They also described the appointments. The measurements were collect this information. Mechanical process for recording the neutral zone, recorded at the first appointment and digitizing systems rely on touch probes the maxillary and mandibular anterior inserted at the second appointment. (tactile),6,7 whereas optical digitizing teeth position, the palatal morphology, systems use cone beam computed to- the occlusal vertical dimension, and the TECHNIQUE mography,8,9 laser,5 or light-emitting interocclusal relation so these could be diode scanners.5,6 These data are pro- included as part of the process of 1. Make a definitive impression cessed by software and then used fabricating the bases. Furthermore, they with the impression materials and ther- to fabricate the desired object or used a prototype of 3-dimensional moplastic moldable trays which are aAssistant Professor, Louisiana State University Health Sciences Center. bAssistant Professor, Division of Restorative and Prosthetic Dentistry, The Ohio State University. cProfessor, Division of Restorative and Prosthetic Dentistry, The Ohio State University. dAdjunct Clinical Professor, Division of Restorative and Prosthetic Dentistry The Ohio State University. Infante et al 2 Volume - Issue -

available in different sizes (AvaDent). the residual ridge (Fig. 3). If the residual AMD as far posteriorly as possible and Initially, mix the 2 part heavy-consistency ridge is between sizes, use the smaller place it horizontally (Fig. 4). polyvinyl siloxane (PVS) and press it AMD size. With the existing dentures in 6. Place both AMDs into the into the existing denture to create a the mouth, assess the occlusal vertical mouth and attach the AvaDent ruler PVS cast. dimension (OVD) and rest position (Fig. 5). Align the ruler parallel to the 2. Measure the residual ridge and with a preferred assessment method.12 interpupillary line and record the angle select the appropriate thermoplastic Establish whether these dimensions are that will be used to correlate the tray. Place the tray in a hot water bath correct or whether they need to be completed AMD to the virtual (77C) and mold to the cast. altered. Once established, place dots mounting with software algorithms. 3. Evaluate the tray intraorally to on the patient’s facial features and re- With the central bearing tracing device ensure it covers all the appropriate cord the OVD with a caliper. resting on the mandibular tray, adjust anatomic areas and adjust the borders 5. Coat the AMD maxillary tray the OVD by turning the fitting on the as needed. As with any conventional with the specified adhesive (Express fast side of the AMD to raise and lower the edentulous impression technique, dry set polyvinyl siloxane PVS max- central bearing pin (Fig. 6). Then the tissue with gauze. First, border the illomandibular registration record; Xer- confirm the OVD. To confirm the mold with heavy-body material and tec) material onto the tray and place with a gothic arch make the definitive impression with a intraorally to stabilize the AMD on the tracing, coat the tip of the bearing pin regular-set light-body PVS material residual ridge before making the re- with a marking agent, coat the (Figs. 1, 2). cords. Coat the AMD mandibular tray mandibular tray with occlusal spray, or 4. Choose the correct size anatomic with adhesive, express the PVS max- rub it with occlusal paper. Guide the measuring device (AMD) (1 of 3 avail- illomandibular relationship record ma- patient’s mandible back and trace able sizes) (AvaDent) by using the terial onto the tray, and place the tray lateral, anterior, and posterior excur- caliper to measure the widest part of in the mouth. Extend the mandibular sions on the mandibular tray with the

1 Maxillary definitive impression. 2 Mandibular definitive impression.

3 Maxillary and mandibular anatomic measuring devices 4 Maxillomandibular relationship record material being (AMDs). expressed into AMD maxillary tray. The Journal of Prosthetic Dentistry Infante et al - 2014 3

5 Registration of interpupillary line. 6 OVD adjustment by turning screw on side of AMD.

7 Stabilization of AMD by injecting maxillomandibular 8 Use of composite resin to stabilize transparent guide. relationship record material into area between maxillary and mandibular trays. bearing pin. Direct the patient to “keep the esthetic transparent guide onto the 11. Once processed, the dentures are jaws together,”“slide lower jaw as far existing denture. Use 1 of 3 overlay returned to the for delivery to forward as possible,”“as far back as esthetic transparent guides, which repre- the patient (Fig. 10). possible,” and “as far left and right as sent different tooth sizes. Once the possible.” Create the gothic arch proper transparent guide is chosen, tracing accordingly. establish the desired gingival height and DISCUSSION 7. Remove the mandibular tray and mark it on the prescription. Mark the drill a divot into the tray at the tip of midline and incisal edge for the anterior Many materials have been used in the arrow. Replace the tray intraorally, teeth on the lip support. Place composite the fabrication of denture bases. From place the tip of the pin into the divot, resin (Tetric EvoFlow; Ivoclar Vivadent) wood to porcelain, no material has and stabilize the AMD by liberally onto the transparent guide and adhere received the same attention or gained injecting maxillomandibular relation- this to the lip support. With the AMD in the same popularity as PMMA [poly(- ship record material into the area be- the mouth, verify the esthetics and OVD methyl methacrylate)].13-15 Although tween the maxillary and mandibular (Fig. 8). it is the most common material AMD trays (Fig. 7). Remove any record 9. Send both the completed im- used today, PMMA is not without material from the maxillary AMD that pressions and the final AMD to the problems. These problems are related to might interfere with the drape of the lip. laboratory for fabrication of the processing, porosity, fracture strength, Adjust the lip support to the desired lip dentures. dimensional stability, color stability, fullness by turning the fitting on the 10. Examine the digital preview vir- and biocompatibility (allergenic re- anterior of the lip support. tual setup sent by the laboratory, and actions).16,17 Challenges with the use of 8. As a guide for selecting the modify the design of the denture if PMMA bases are being met by either appropriate denture tooth mold, overlay needed (Fig. 9). improving the qualities and properties Infante et al 4 Volume - Issue -

sockets are milled with a 5-axis milling machine. The sockets for the selected teeth are milled according to the posi- tion of the selected teeth. The selected teeth are chemically bonded to the AvaDent base material by means of a proprietary PMMA bonding technique that uses heat and pressure, or if requested, a clinical evaluation of the denture can be selected. The teeth are set into the milled sockets in wax and returned to the dentist for evaluation, allowing for movement of the anterior and posterior teeth, adjustment of 9 Virtual arrangement. the , and adjustment of the denture base. In the wax evaluation method, the teeth are attached to the base with conventional techniques. Should the patient not have existing dentures, irreversible hydrocolloid im- pressions are made and casts are poured. The thermoplastic trays are adapted to these casts. The vertical dimension of rest is obtained by the use of phonetics, specifically the bilabial sounds. Once obtained, the OVD is calculated. The same technique is then followed as with a patient who has existing dentures. 10 Maxillary and mandibular complete dental prosthesis. The stability of a denture, that is the ability to “resist displacement by func- of the material or the use of alternative vertical height. A virtual record base is tional horizontal or rotational stresses,” materials.18-22 The AvaDent dentures created, and functional controls are depends to a great degree on the oc- are produced by machining a pre- then applied. The algorithms for the clusion and base adaptation.24 The formed cylinder of acrylic resin mate- occlusal arrangement are written using transfer of concentrated stresses from rial. This cylinder is produced under traditional rules.12 The occlusal plane the denture base to the underlying high pressure and heat, which prevents is set from the incisal edges of the supporting structures has been associ- shrinkage of the definitive milled pros- mandibular teeth to halfway up the ated with trauma to the tissues and thesis. As a result of the highly con- retromolar pad, and the curves of accelerated bone resorption.25-27 In the densed resin, there is a decrease in free Spee and Wilson are incorporated into currently described technique, there monomer, a decrease in the porosity the software to create the optimum should be reduced dimensional sta- when compared to a conventionally occlusal arrangement on the basis of bility problems because the denture is processed denture, and a decrease in the operator’s preference. Lingualized milled from preformed acrylic resin. the retention of Candida albicans by the or monoplane occlusal schemes may be This quality should compare favorably denture base.10 Manufactured acrylic chosen.23 The designed software ar- to bases fabricated with conventional resin teeth, which are not CAD/CAM ranges the teeth according to the spe- processing techniques. This may con- produced, are used. cific guidelines of the desired occlusion, tribute to the improved stability and The fabrication in the laboratory with the transparency being the guide retention of the denture base with less starts with relating the scanned maxil- for the maxillary anterior teeth. A digital trauma and fewer postinsertion ad- lary and mandibular impressions to the preview is sent to the dentist, who can justment visits. scanned AMD. The 2 files are digitally examine the virtual setup and modify The digital system facilitates the overlaid and merged by best-fit trian- the design of the denture. completion of dentures in 2 visits. Im- gulation. Millions of digital triangles Once the design of the teeth is pressions, occlusal relation records, and overlap each other to form a vertical accepted by the clinician, the intaglio an orientation record are made at the representation of jaw position and surfaces of the denture and tooth first visit and the dentures inserted at the The Journal of Prosthetic Dentistry Infante et al - 2014 5

second. This significantly reduces the alternative techniques are being intro- 10. Bidra AS, Taylor TD, Agar JR. Computer- time the patient spends in the dental duced. Further, the system does not aided technology for fabricating complete fi dentures: systematic review of historical of ce. Unlike in the fabrication of con- provide for all schemes of occlusion, background, current status, and future ventional dentures, there is no facebow and no long-term results have been perspectives. J Prosthet Dent 2013;109: record. If the maxillomandibular record published. Long-term clinical trials 361-6. 11. Bidra AS. The 2-visit CAD-CAM implant- is made at the correct OVD, the lack of should be performed to evaluate the retained overdenture: a clinical report. J Oral facebow should not cause any error. A success of the technique presented. Implantol. In press. repository of the digital record is stored, 12. Boucher CO. Swenson’s . and an exact duplicate denture can be SUMMARY St Louis: Mosby; p. 125-6. 13. Moriyama N, Hasegawa M. The history of reproduced at any time. The denture can the characteristic Japanese wooden denture. be designed according to the dentist’s A technique for the fabrication of a Bull Hist Dent 1987;35:9-16. specifications. Bases can be fabricated CAD/CAM denture is described. By using 14. Ladha K, Verma M. 19th century denture an AMD, the dentist can make clinical base materials revisited. J Hist Dent with various anatomic features, in- 2011;59:1-11. cluding stippling, rugae, thickness of records in 1-step appointments. The 15. Yap CC. Developments in prosthetic dentistry the actual base, and borders of the AMD allows the clinician to gather all the in the nineteenth century. Bull Hist Dent clinical information needed with a single 1987;35:43-51. dentures. A wax evaluation can also be 16. Rickman LJ, Padipatvuthikul P, requested. Various shades of acrylic intraoral device. The virtual denture is Satterthwaite JD. Contemporary denture resins are available for the fabrication of milled to exact specifications without the base resins: part 1. Dent Update 2012; the bases, and manufactured acrylic use of conventional stone models or 39:25-8, 30. fl 17. Rickman LJ, Padipatvuthikul P, resin teeth are used. The denture teeth asking and processing techniques. Satterthwaite JD. Contemporary denture are placed virtually and the bases with base resins: part 2. Dent Update 2012;39: tooth sockets milled. The exact positions REFERENCES 176-8, 180-2, 184. 18. Matthews E, Smith DC. Nylon as a denture of the teeth are recorded. These tooth 1. Davidowitz G, Kotick PG. The use of CAD/ base material. Br Dent J 1955;98:231-7. positions are compared to a scan made CAM in dentistry. Dent Clin North Am 19. Hargreaves AS. Nylon as a denture-base of the denture and tooth positions after 2011;55:559-70. material. Dent Pract Dent Rec 1971;22: 2. Goodacre CJ, Garbacea A, Naylor WP, 122-8. the dentures have been fabricated. A Daher T, Marchack CB, Lowry J. CAD/CAM 20. Stafford GD, Huggett R, MacGregor AR, virtual remount is possible, and where fabricated complete dentures: concepts and Graham J. The use of nylon as a denture-base discrepancies are noted, the equilibra- clinical methods of obtaining required material. J Dent 1986;14:18-22. morphological data. J Prosthet Dent tion of the teeth is completed in the 21. Jameson WS. Fabrication and use of a metal 2012;107:34-46. reinforcing frame in a fracture-prone milling center and clinical remount 3. E4D CAD/CAM systems. Put dental team in mandibular complete denture. J Prosthet procedures are avoided. A denture kit is control. Compend Contin Educ Dent Dent 2000;83:476-9. 2012;33:542. provided with all the materials required 22. Fredrickson EJ. A one-piece, all vinyl denture. 4. Christensen GJ, Child PL Jr. Fixed prostho- Quintessence Dent Technol 1979;3:9-12. to make the initial records and impres- dontics: time to change the status quo? Dent 23. Lang BR. Complete denture occlusion. Dent sions. The actual scanning of records is Today 2011;30:66, 68, 70-73. Clin N Am 2004:641-65. made off-site, eliminating the need for 5. Beuer F, Schweiger J, Edelhoff D. Digital 24. The glossary of prosthodontic terms. dentistry: an overview of recent developments J Prosthet Dent 2005;94:10-92. the dentist to purchase expensive ma- for CAD/CAM generated restorations. Br 25. Carlsson GE. Responses of jawbone to pres- chines. Commercial laboratories can Dent J 2008;204:505-11. sure. Gerodontology 2004;21:65-70. now scan impressions and design the 6. Quaas S, Rudolph H, Luthardt RG. Direct 26. Jozefowicz W. The influence of wearing den- mechanical data acquisition of dental dentures; however, all denture base tures on residual ridges: a comparative study. impressions for the manufacturing of CAD/ J Prosthet Dent 1970;24:137-44. milling is done at the central laboratory. CAM restorations. J Dent 2007;35:903-8. 27. Atwood DA. Some clinical factors related to Complete dentures, immediate den- 7. Persson AS, Andersson M, Oden A, Sand- rate of resorption of residual ridges. borgh-Englund G. Computer aided analysis J Prosthet Dent 2001;86:119-25. tures, and implant dentures can be of digitized dental stone replicas by dental fabricated with this system. CAD/CAM technology. Dent Mater 2008; Although initial results are prom- 24:1123-30. Corresponding author: ising, the technique has some disad- 8. Kanazawa M, Inokoshi M, Minakuchi S, Dr Burak Yilmaz Ohbayashi N. Trial of a CAD/CAM system The Ohio State University, College of Dentistry vantages. The central bearing tracing for fabricating complete dentures. Dent Division of Restorative and Prosthetic Dentistry device can be a challenging method of Mater J 2011;30:93-6. Columbus, Ohio 43210 recording jaw relationships. Although 9. Inokoshi M, Kanazawa M, Minakuchi S. E-mail: [email protected] Evaluation of a complete denture trial the recording of the gothic arch tracing method applying rapid prototyping. Dent Copyright ª 2014 by the Editorial Council for in some patients may be difficult, Mater J 2012;31:40-6. The Journal of Prosthetic Dentistry.

Infante et al