A Comparative Study of Bone Densitometry During Osseointegration: Piezoelectric Surgery Versus Rotary Protocols

QUINTESSENCE INTERNATIONAL

A comparative study of bone densitometry during osseointegration: Piezoelectric surgery versus rotary protocols

Luca Di Alberti, DDS, PhD1/Federica Donnini, RDH2/ Claudio Di Alberti, DDS2/Michele Camerino, DDS3

Objectives: To date, there have been no studies on the outcome of osseointegration of alveolar bone around dental implants inserted with piezoelectric osteotomy versus conventional osteotomy. The aim of this study was to compare the radiographic differences, through evaluation of peri-implant bone density, between implant insertion using traditional surgical technique and piezoelectric technique. Method and Materials: Forty patients were selected whose treatment consisted of a minimum of two implants placed in nonpathologic native bone. A single type of implant surface (SLA) was chosen. The implants were placed following the manufacturer protocol for traditional surgical technique and piezoelectric technique. Radiographs were taken following surgery and 30, 60, and 90 days after surgery. The bone density was studied with the densitometry application. Results and Conclusion: All patients completed the study period with success. Despite a limited number of treated patients, the results of this pilot study demonstrated that (1) piezoelectric implant site preparation promotes better bone density and osteogenesis, and (2) the piezoelectric technique is predictable, with a 100% success rate in this study. (Quintessence Int 2010;41:639-644)

Key words: bone density, implants, osseointegration, surgery, ultrasound.

Osseointegration of dental implants is highly Piezoelectric osteotomy is a technique predictable when implants are completely based on piezoelectric vibration of an embedded in bone.1 In recent years, numerous osteotomic device that permits precise cut- efforts have been made to make implant ther - ting of bone structures without damaging apy safer and with certain clinical results for adjacent soft tissues.3 Ultrasonically moved potential patients by simplifying clinical proce- knives have the ability to cut hard tissues, dures. One of these efforts has been the reduc- such as teeth and bone. In contrast, soft tis- tion of the healing period using new implant sues (eg, gingiva, blood vessels, nerves, and surfaces that may shorten and improve the sinus membranes) are preserved from injury osseointegration process. Albrektsson et al2 because they vibrate with the tip. This makes recognized in the early age of implantology that piezoelectric surgery particularly suitable for the implant surface, including topography, a broad spectrum of surgical applications, chemistry, surface charge, and wettability, is including apicectomy, bone block section- one of the important factors influencing ing, sinus lifting, split-crest technique, nerve osseointegration. lateralization, resective bone surgery, bone scraping, and biopsy sampling.4–9 The Piezosurgery instrument, first developed in 1988, uses a modulated ultrasonic frequency that permits highly precise and safe cutting 1 Visiting Professor, Department of Dental Sciences, University of Foggia, Foggia, Italy. of hard tissue. Nerves, vessels, and soft tis-

2 Private practitioner, Pescara, Italy. sue are not injured by the microvibrations (60

3 Private practitioner, Chieti, Italy. to 200 mm/s), which are optimally adjusted to target only mineralized tissue. The selec- Correspondence: Dr Luca Di Alberti, Via Colonnetta 22, 66100 Chieti, Italy. Fax: +39-0871-562938. Email: [email protected] tive and thermally harmless nature of the

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piezoelectric instrument results in a low bone calcification, and needed a minimum of bleeding tendency. In addition, the instru- two implants placed. All implant sites were in ment can be used in operations requiring nonpathologic native bone. Extraction sites either local or general anesthesia.3 were implanted at least 6 months after tooth The precise nature of the instrument allows extraction. exact, clean, and smooth cut geometries during surgery. The difference in time require- Implant selection ment for surgical procedures using the To better define and restrict this clinicoradio- piezoelectric instrument in comparison with logical study, a single kind of implant surface the conventional drill is negligible. Post- was chosen: sandblasted, large grit, acid- operatively, excellent wound healing of soft etched (SLA). Also, all implants used were tissue injuries could be observed. The range Seven and Biocom (MIS, Shlomi, Israel). The of application of piezoelectric surgery is not implant lengths used were 10 mm, 11.5 mm, limited to minor oral surgery procedures. and 13 mm. Because of its highly selective and accurate nature, with its cutting effect exclusively tar- Traditional surgical technique geting hard tissue, its use may be extended to The implant insertion with traditional surgical more complex oral surgery cases, as well as technique was performed following the manu- to other interdisciplinary problems.10 facturer’s protocol, which includes this drilling The application of ultrasound is emerging procedure: a round bur was used first, fol- as a potent therapy for the treatment of com- lowed by 2- and 3-mm-diameter burs. A single- plex bone fractures and tissue damage. use drill, specific for the implant diameter and Ultrasonic stimuli accelerate fracture healing present in the implant packaging of the com- by up to 40% and enhance tendon and liga- pany, was used to make the final osteotomic ment healing by promoting cell proliferation, bone preparation for implant insertion. migration, and matrix synthesis through an unresolved mechanism.11–15 Piezoelectric technique To date, however, there have been no stud- The implant insertion with piezoelectric tech- ies on the outcome of osseointegration of nique was performed using the new implant alveolar bone around dental implants inserted tips kit made by EMS (Nyon, Switzerland) with piezoelectric osteotomy versus conven- for 20 patients and the new implant tips kit tional osteotomy. The present study evaluated for anterior and poterior maxillary jaws made piezoelectric versus conventional osteotomy by Mectron (Genova, Italy) for the other 20 in alveolar bone osseointegration processes. patients. The aim of this study was to compare the The manufacturer protocols define the radiographic differences, through evaluation of use of the following tip sequence: MB1 to the peri-implant bone density, between implant MB6 for EMS protocol and OP5, IM2, OT4, site preparation with traditional surgical tech- and IM3 for Mectron protocol. The surgical nique burs and piezoelectric technique with perforation was rinsed with sterile double-dis- implant tips (Piezosurgery, Mectron, Genova, tilled water using the perfusion from the tip of Italy; EMS, Nyon, Switzerland). the Piezosurgery or Piezon Master Surgery after every use of the tips. After the use of the last tip, the implants were inserted using the surgical micromotor METHOD AND MATERIALS without the final single-use drill of the implant manufacturer. Patient selection Forty patients (22 males, 18 females) were Radiological follow-up procedure selected to be enrolled in this study. The age Periapical radiographs were taken using the range was 38 to 47 years (mean age 42.5). same x-ray apparatus (Image Rx System, De All patients were healthy, not taking med- Gotzen, Legnano, Italy) and the Kodak 6000 ications that could alter bone metabolism or RVG as a digital sensor (Kodak Carestream

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1 week 12 weeks 1 week 12 weeks Fig 1 Bone densitometry 1 week after surgery and Fig 2 Bone densitometry 1 week after surgery and at 12-week at 12-week follow-up with traditional (left implant) follow-up with traditional (left implant) and piezosurgical site and piezosurgical site preparation (right implant). preparation (right implant). Similar bone density is shown in this clinical case.

Fig 3 Bone densitometry at 6-week follow-up with traditional (left implant) and piezosurgical site preparation (right implant). Bone implant gaps are present 6 weeks 6 weeks in the traditional implant site preparation and a 128 147 124 158 170 142 lower densitometry compared with Piezosurgery.

Health, NY, USA). The exposure time was the RESULTS same for all radiographs. The radiographs were taken immediately after implant inser- All patients successfully completed the tion and 30, 60, and 90 days after surgery. study. All implants were stable and osseoin- Using RVG software analysis, the bone tegrated at the end of the study period, and density was studied with the densitometry no inflammation was recorded during the application. For every implant, four defined healing time (Figs 1 to 9) . and repeatable points were chosen: the The mean bone density value of all microthreads area, the first coronal thread, implants after piezoelectric implant insertion the middle part of implant, and the last apical (bone density at T0 = 167 for the Mectron thread of the implant. The values were evalu- group and 160 for the EMS group) was high- ated mesially and distally for every implant. er than the traditional drilling procedure (bone Every data point was converted into a data density at T0 = 135 and 137 for traditional value, which was correlated with the same data groups) and did change after a 3-month peri- point/value over the follow-up period to create od (bone density at T1 = 168 for the Mectron a histogram of the bone density during the group and 175 for the EMS group vs 142 and osseointegration process. All data points/val- 140 for the traditional groups). ues were recognized in every implant placed Bone quality was categorized according to using both surgical procedures. Then, all data the classification by Norton and Gamble16 points/values of a single implant surface, (Table 1), who correlated their findings of mesially and/or distally, were summarized. bone density of alveolar bone with the sub- The mean and the median values were com- jective quality classification described by pared between the traditional surgical proce- Lekholm and Zarb.17 In Lekholm and Zarb’s dure and the piezoelectric procedure. classification, quality 1 describes homoge- nous compact bone of high quality. Quality

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1 week 4 weeks 1 week 4 weeks Fig 4 Bone densitometry 1 week after surgery and Fig 5 Bone densitometry 1 week after surgery and at 4-week follow-up with traditional site prepara- at 4-week follow-up with EMS ultrasonic site prepa- tion. A good bone implant contact is present. ration. Presence of a more dense bone at 4 weeks.

4 weeks 12 weeks 12 weeks 12 weeks Fig 6 Bone densitometry 4 weeks after surgery and at 12-week follow-up with traditional site Fig 7 Bone densitometry at 12-week follow-up preparation. The cementoma lesion is still present with traditional (left implant) and piezosurgical site and with same volume. preparation (right implant).

4 weeks 12 weeks Fig 8 Bone densitometry 4 weeks after surgery Fig 9 Bone densitometry after 12-week follow-up and at 12-week follow-up with EMS ultrasonic site with EMS ultrasonic site preparation. A definitive preparation. A high density bone is present at 12 presence of highly dense bone is present, and the weeks and resembles the histological bone canali- implant appears fully osseointegrated. culi view of a calcified bone.

2/3 describes a “straightforward therapeutic There was no statistically significant differ- situation,” providing the implant with good pri- ence in resorption rates between implants mary fixation. Caution is warranted over the inserted in the maxilla and in the mandible placement of implants into inadequate quality with the piezoelectric technique. The statisti- 4 bone. Quality 4 describes a “failure zone.” cal significance was P = .042 (ANOVA).

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Table 1 Bone quality according to the classiﬁcation by Norton and Gamble16

Quality Bone density range (HU) Region of interest (Lekholm and Zarb17) (Norton and Gamble16)

Quality 1 > + 850 Anterior mandible Quality 2/3 + 500 to + 850 Posterior mandible/anterior maxilla Quality 4 0 to + 500 Posterior maxilla Quality 4* < 0 Tuberosity region

DISCUSSION purines, such as adenosine triphosphate, activating P2Y receptors, mainly the P2Y(1) Piezoelectric osteotomy is a technique based receptor.12 Research on LIPUS in animal frac- on ultrasonic vibration of an osteotomic device ture models has demonstrated promising that permits precise cutting of bone structures results for acceleration of fracture healing and without damaging adjacent soft tissues.3 for promotion of fracture healing in compro- The application of ultrasound is emerging mised tissue beds. A large body of cellular as a potent therapy for the treatment of com- and animal research exists, which shows that plex bone fractures and tissue damage. The LIPUS may be beneficial for accelerating nor- ultrasonic devices transform the vibrations of mal fracture healing or for promoting fracture the tips into motion energy and heat. The healing in compromised tissue beds.12–15 motion energy produces the cutting action, Scheven and colleagues postulate that low- and the heat produced is reduced with irri- frequency, low-intensity ultrasound may stimu- gation. Some devices are capable of trans- late endogenous coronal tooth repair by forming most of the vibrations into energy stimulating dentin formation from existing and will not produce heat on the end of the odontoblasts or by activating dental pulp stem tip. Other devices may become too hot and cells to differentiate into new reparative dentin- can cause burns on the soft tissues, while producing cells. They also believe that ultra- other devices remain cold during use. sound therapy could promote dentin formation Ultrasonic stimuli accelerate fracture heal- and repair and that it may have the potential ing by up to 40% and enhance tendon and lig- benefit of alleviating dentin hypersensitivity by ament healing by promoting cell proliferation, inducing occlusion of dentinal tubules. It is migration, and matrix synthesis through an envisaged that therapeutic ultrasound may be unresolved mechanism.11–15 Ramli et al11 inves- used in the future to facilitate dental tissue engi- tigated the effect of short-wave (1-MHz) and neering and stem cell therapy applications for long-wave (45-kHz) ultrasound on the vascu- dental tissue regeneration.15 larity of the chorioallantoic membrane (CAM) As ultrasound is able to promote biological of a fertilized egg and demonstrated that effects on odontoblast-like cells,15 on osteo - ultrasound methods showed evidence of an blasts, and on osteogenic cells, we have pos- angiogenic effect compared to controls. The tulated that ultrasound could have potential most effective results were seen with direct benefits in osseointegration. Our results, based application of a 45-kHz wave at an intensity of on radiological findings, denote promising 15 mW/cm2 and indirect application of the results on bone density surrounding implants. media of fibroblasts ultrasonicated at 1 MHz Since this density measurement is based on with an intensity of 0.4 W/cm2. This model has the pseudo-color visualization of the digital confirmed that ultrasound can induce neo - imaging software, a future study for revalidation angiogenesis in vivo.11 Low-intensity pulsed of the density measurements with another type ultrasound (LIPUS) is commonly used in the of analysis, such as cone beam computed treatment of fractures and nonunion-promoting tomography, is indicated. The short follow-up acceleration of healing fractures, and it period is exclusively associated with the time in induces osteoblastogenesis via the release of the market of the two ultrasonic implant kits.

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