Prospective randomized clinical comparison of 2 dental implant navigation systems.

PURPOSE: The aim of this prospective randomized study was to compare the clinical accuracy of and surgical time required for mandibular dental implant placement with 2 computer-assisted navigation systems using pre- and postoperative computerized tomographic (CT) data. MATERIALS AND METHODS: In 16 patients with edentulous mandibles, 4 interforaminal implants per patient were placed with computer-assisted navigation. The implant bed was prepared by transmucosal drilling without mucosal punching. Patients were randomly allocated to either the VISIT navigation system (32 implants; 8 patients) or the Medtronic StealthStation Treon navigation system (32 implants; 8 patients). Pre- and postoperative CT scans were matched using the normalized mutual information 3D registration algorithm to compare preplanned and final implant positions. Operation room time was recorded from start of preoperative preparations to end of surgery. RESULTS: All implants were placed as planned; there were no intra- or postoperative complications. Average implant deviation errors of 0.7 mm and 0.9 mm were recorded for the VISIT and StealthStation Treon navigation systems, respectively. Timing revealed an average operation room time of 81.3 +/- 15.8 minutes for the VISIT navigation system and 60 +/- 10.4 minutes for the StealthStation Treon navigation system. CONCLUSIONS: The accuracy of implant bed preparation and placement was similar in both systems. Both navigation systems are equally precise in a clinical environment. However, total operation room time was 25% shorter with the StealthStation Treon navigation system, probably because of the faster tracking system update rate.

Navigated flapless transmucosal implant placement in the mandible: a pilot study in 20 patients.

PURPOSE: The aim of this study was to assess whether navigated flapless transmucosal implant bed preparation allows placement of dental implants in edentulous mandibles. MATERIALS AND METHODS: Each patient was scheduled to receive 4 screw-shaped Ankylos (Dentsply Friadent) implants in the interforaminal region. The VISIT navigation system was used for guided drilling. The mucosa was penetrated without flap elevation. The study protocol did not allow direct visualization of the bone surface during surgery. Data analysis included computed measurements on pre- and postoperative computerized tomographic (CT) images. RESULTS: Twenty patients with fully edentulous mandibles (14 male, 6 female) were included in the study. Computer-based planning for 80 implants was performed intraoperatively. Two implants (2.5%) were not primarily stable because of buccal bone fenestration, which occurred because of uncontrollable shifting of the dental implant drill. These implants were immediately removed. Postoperative CT image evaluation revealed a mean deviation of 0.7 mm in all directions. CONCLUSIONS: Navigated flapless transmucosal interforaminal implant placement was found to be a precise, predictable, safe procedure in patients with smooth wide regular mandibular ridges. The technique was less accurate and more complicated in areas where irregular bone existed.

Surface area analysis of dental implants using micro-computed tomography.

OBJECTIVES: In this study, we present and evaluate a micro-computed tomography (micro-CT)-based method for the calculation of the potential bone/implant contact area (p-BICA) on the surface of dental implants. MATERIAL AND METHODS: For seven commercially available implants (Ankylos implant, Brånemark System, Frialit CELLplus, Replace((R)) Select Tapered, Straumann Solid screw, XiVE S CELLplus, 3i Osseotite XP Threaded Miniplant, the p-BICA surface is determined by means of three-dimensional X-ray computed-tomography and computer-based data processing. Measurements were repeated two times, and the stability and repeatability of the measurement method were evaluated. RESULTS: Our analysis revealed a p-BICA of 118 mm(2) for the XiVE S CELLplus implant, 134 mm(2) for the Ankylos, 136 mm(2) for the Frialit CELLplus, 138 mm(2) for the Brånemark System, 139 mm(2) for the Replace((R)), 159 mm(2) for the 3i Osseotite XP and 199 mm(2) for the Straumann Solid screw implant. The measurement method proved to be stable and led to reproducible results. CONCLUSIONS: The micro- and macrostructure of dental implants define the surface and the p-BICA. Precise determination of this parameter can be achieved by means of the micro-CT-based method as presented in this study. The value of p-BICA lies in the predictability of industrial design before preclinical and clinical testing. Based on this method, dental implant properties become comparable even if geometrical details are not disclosed by the manufacturer.

Computer-guided flapless placement and immediate loading of four conical screw-type implants in the edentulous mandible.

AIM: The aim of this prospective study was to evaluate the outcome of computer-guided flapless placement and immediate loading of four conical screw-type implants in the interforaminal region. PATIENTS AND METHODS: From May to August 2003, 25 consecutive patients (m : f=16 : 9) with edentulous mandibles were included in the study. After transmucosal drilling with computer-assisted navigation, four implants were placed in the interforaminal region. The lower dentures were converted and implants immediately loaded. RESULTS: One-hundred implants were successfully placed. In two patients, all implants had to be submerged because of insufficient primary stability of one of the implants; another patient declined to receive immediate loading of implants after surgery and was lost to follow-up. During follow-up of the remaining 22 patients with 88 immediately loaded implants, loosening of four implants (4.5%) was seen in three patients. In these cases, immediate loading was terminated and all implants submerged; subsequently, two implants were lost in one patient, while the other two implants re-osseointegrated. The cumulative survival and success rates of immediately loaded implants were 97.7% after 2 years. Prosthetic success was 100%. CONCLUSION: Transmucosal computer-assisted placement and immediate loading of mandibular implants is a high-end approach to edentulism that provides excellent results while being minimally invasive.

Preliminary report on a staged ridge splitting technique for implant placement in the mandible: a technical note.

PURPOSE: Narrow edentulous alveolar ridges less than 5 mm wide require horizontal augmentation for the placement of screw-type dental implants. A staged approach to ridge splitting in the mandible to decrease the risk of malfracture during osteotomy is presented. MATERIALS AND METHODS: Five consecutive patients with 6 long-span edentulous areas of the mandibular ridge were included in this study. After corticotomy of a rectangular buccal segment and a 40-day healing period, the mandibular ridge was split, leaving the buccal periosteum attached to the lateralized segment. Seventeen dental implants were placed, and the gap between the implants and the bone filled with a mixture of venous blood and a porous algae-derived hydroxyapatite. RESULTS: All buccal segments fractured as planned at the basal corticotomy during ridge splitting. After 6 months, all implants were stable and surrounded by bone; prosthetic loading with fixed partial dentures was successful in all cases. DISCUSSION: In the mandible, greenstick fracture during widening with osteotomes has not been controllable to date because of cortical thickness of the bone; the risk of malfracture during single-stage ridge splitting was high. With this approach, the location of the greenstick fracture is predetermined, and the perfusion for the buccal segment remains intact, although vascularization shifts from internal perfusion from spongy bone after the first intervention to external perfusion from the periosteum after the second intervention. The buccal cortical segment remains a pedicled graft after ridge splitting. CONCLUSION: The preliminary results of this report indicate that staged ridge splitting can be a safe technique which overcomes the problems associated with single-stage ridge expansion/ridge splitting procedures without causing significant delay in treatment.

Computer-guided flapless transmucosal implant placement in the mandible: a new combination of two innovative techniques.

OBJECTIVE: To assess whether computer-guided flapless transmucosal implant bed preparation without mucosal punching allows placement of dental implants in edentulous mandibles. STUDY DESIGN: Twenty patients with fully edentulous mandibles (11 male; 9 female) were included in the study. Each patient was scheduled to receive 4 screw-shaped Ankylos (Dentsply Friadent, Mannheim, Germany) implants in the interforaminal region. The StealthStation Treon navigation system (Medtronic, Minnesota, MN) was used for computer-guided drilling. Using conventional implant drills the mucosa was penetrated without flap elevation or mucosal punching. The study protocol did not allow direct visualization of the bone surface during surgery. RESULTS: For 78 implants (97.5%) the preoperative plan could be transfered to the patient by intraoperative navigation with a mean deviation of 0.9 mm (Implant tip 0.8 +/- 0.6 mm; coronal implant end 1.1 +/- 0.7 mm) as measured by comparing pre- and postoperative computerized tomography images. Two implants (2.5 %) were not primarily stable and failed to osseointegrate. CONCLUSIONS: Computer-guided transmucosal interforaminal implant placement without mucosal punching is a precise and predictable procedure. It is, however, not yet suitable for all bone morphologies. Future developments may include miniaturization of hardware and simplification of the drilling procedure.

Complications after zygoma fracture fixation: is there a difference between biodegradable materials and how do they compare with titanium osteosynthesis?

OBJECTIVE: Biodegradable materials are particularly useful for the fixation of zygomatic fractures. Different systems are commercially available. The aim of this study was to compare the clinical outcome of zygomatic fracture fixation using 3 biodegradable systems and a titanium osteosynthesis system. STUDY DESIGN: Patients with displaced fractures of the zygomatic bone presenting at our department from October 2001 to May 2003 were randomly allocated to 1 of 3 treatment groups for fracture fixation (study group A: LactoSorb: n = 18; study group B: BioSorb: n = 18; study group C: Delta: n = 18). Treatment outcome and complication rates were compared with a historic patient group with zygomatic fractures fixed with titanium osteosynthesis (control group D: n = 15). RESULTS: A total of 64 patients (study groups A + B + C: n = 49; control group D: n = 15) were followed for at least 24 months (range: 24 to 44 months). Forty-nine patients in the biodegradable study groups (group A: n = 15; group B: n = 17; group C: n = 17) who had their fractures fixed with biodegradable plates and screws alone or in combination with titanium plates and screws were reviewed postoperatively. Uneventful healing occurred during the entire follow-up period in 39 (80%) out of 49 patients in the biodegradable groups (A + B + C) and in 12 (80%) out of 15 patients in group D. Ten patients in groups A + B + C developed postoperative complications (infection: n = 3; soft tissue dehiscence: n = 2; implant-related tissue reactions: n = 5), compared with 3 patients in group D (soft tissue dehiscence: n = 1; unspecific pain: n = 2) (P = .97). Complications occurred in 4 patients in group A and 3 patients each in groups B and C. Smokers developed significantly more postoperative complications than nonsmokers in groups A + B + C (P = .01). CONCLUSION: There was no significant difference between biodegradable osteosynthesis materials or between biodegradable materials and titanium fixation with respect to fracture healing and postoperative complications. Postoperative complications were of a minor nature and resolved spontaneously or after local therapy. Smoking habits may play a significant role in the incidence of complications with biodegradable materials.

An evaluation of the clinical application of three different biodegradable osteosynthesis materials for the fixation of zygomatic fractures.

OBJECTIVE: The aim of this prospective study was to compare the clinical handling of 3 different biodegradable osteosynthesis materials and to determine whether they can be used for the fixation of all types of zygomatic fractures. STUDY DESIGN: A total of 54 consecutive patients who presented with displaced fractures of the zygomatic bone between October 2001 and May 2003 were randomly allocated to 3 biodegradable material groups for the fixation of the fractures. A titanium fixation system was used as rescue osteosynthesis whenever biodegradable materials failed. RESULTS: Seventy-one (75.5%) of 94 fracture sites were fixed with biodegradable osteosynthesis; 23 (24.5%) had to be fixed with titanium plates and screws. No statistically significant difference was found between the 3 biodegradable materials with regard to their suitability for zygomatic fracture fixation (P = .16). Nonstable fixation (n = 7) or the need to fix small fragments (n = 16) were the reasons for using the titanium fixation system as rescue osteosynthesis at these sites. Biodegradable materials were most frequently unfeasible for use at the infraorbital rim and in the zygomaticomaxillary/anterior sinus wall area. CONCLUSIONS: It was possible to stabilize 3 of 4 zygomatic fractures with 1.5- or 1.7-mm biodegradable osteosynthesis. Insufficient fracture stabilization, especially at the infraorbital rim and the zygomaticomaxillary crest/anterior sinus wall, was the main reason to switch to titanium osteosynthesis. The biodegradable screw design is possibly too bulky for these particular bony structures.

Analysis of complications following alveolar distraction osteogenesis and implant placement in the partially edentulous mandible.

OBJECTIVE: The purpose of this retrospective study was to evaluate complications before, during, and after vertical alveolar distraction osteogenesis and to assess the survival rate of dental implants placed in distracted bone. STUDY DESIGN: In a consecutive series, 37 patients with 45 alveolar ridge deficiencies of the partially edentulous mandible were treated with 14 intraosseous and 31 subperiosteal distraction devices. Seventy-two dental implants could be placed at the time of distractor removal and 21 implants at a second stage. RESULTS: Complications associated with the distraction procedure affected 75.7% of patients. The majority of complications were of minor nature with the exception of fractures of basal bone (n = 3), fracture of transport segment (n = 1), breakage of distractor (n = 1), and severe mechanical problems (n = 3). Eleven secondary grafting procedures were necessary to allow the placement of dental implants. Implant survival was 95.7% (mean postloading follow-up: 35.7 months). CONCLUSION: Vertical alveolar distraction osteogenesis is not an uncomplicated procedure; however, long-term survival of dental implants inserted into distracted areas is satisfactory.

Biodegradable fixation of mandibular fractures in children: stability and early results.

OBJECTIVE: The aim of this study was to assess the safety and efficiency of biodegradable self-reinforced (SR-PLDLA) bone plates and screws in open reduction and internal fixation of mandible fractures in children. STUDY DESIGN: Thirteen patients (5 female, 8 male; mean age 12 years, range 5-16 years) were operated on various fractures of the mandible (2 symphyseal, 6 parasymphyseal, 4 body, 3 angle, 1 ramus, 2 condylar fractures). The mean follow-up time was 26.4 months (range 10.9-43.4 months). Intermaxillary fixation was applied in cases with concomitant condylar fractures up to 3 weeks. RESULTS: Primary healing of the fractured mandible was observed in all patients. Postoperative complications were minor and transient. The outcome of the operations was not endangered. Adverse tissue reactions to the implants, malocclusion, and growth restrictions did not occur during the observation period. CONCLUSIONS: Pediatric patients benefit from the advantages of resorbable materials, especially from faster mobilization and the avoidance of secondary removal operations. Based on these preliminary results, self-reinforced fixation devices are safe and efficient in the treatment of pediatric mandible fractures. However, further clinical investigations are necessary to evaluate the long-term reliability.

Experience with microvascular free flaps in preoperatively irradiated tissue of the oral cavity and oropharynx in 303 patients.

This study examined free flap reconstruction of surgical defects of the oral cavity and oropharynx after preoperative radiochemotherapy. Included in this analysis are 303 prospectively followed patients who underwent a multimodal treatment regime for advanced oral and oropharyngeal carcinoma. All patients received preoperative radiochemotherapy (Mitomycin C, 5-FU, 50 Gy), ablative surgery, and primary free flap reconstruction. Patient characteristics, surgical parameters like duration of surgery and ischaemia, size of defect, type of transplant, and clinical outcome parameters like duration of intensive care and hospitalization, type of complications, necessity and type of revision surgery were statistically evaluated. Overall flap success rate was 93.1%. Sixty seven patients required revision and 21 flaps (6.9%) were lost. Overall complication rate was 22.1%. Mean duration of intensive care (DOIC) and duration of overall postoperative hospitalization (DOH) were 11.0+/-9.6 days and 35.9+/-26.3 days, respectively. Flap success and flap related complications after 50 Gy focal radiation dosage were found in a comparable range as in published series of reconstructions in uncompromised tissue.

Self-reinforced biodegradable plates and screws for fixation of zygomatic fractures.

PURPOSE: The aim of this retrospective clinical study was to evaluate zygomatic fracture fixation with the BioSorbFX osteosynthesis system by assessing stability of reduction as well as complications in the first postoperative year and by conducting a survey to document surgeons' opinions on biodegradable osteosynthesis for this indication. MATERIAL: From January to September 2003, 25 patients with displaced non-infected unilateral fracture of the zygoma were operated upon (m:f = 20:5; age 17-81 years; mean 39.4 years) using the BioSorbFX 2.0 and/or 1.5 mm osteosynthesis systems. METHODS: A: Clinical and radiographic examinations were carried out immediately postoperatively and after 1, 3, 6, 9 and 12 months. METHODS: B: Surgeons were asked to participate in a survey critically evaluating their experience with biodegradable osteosynthesis systems. RESULTS: A: All fractures of the zygoma healed uneventfully. An excessive soft tissue reaction due to the degradation process was not seen. Three minor complications which resolved after local therapy occurred in the immediate postoperative phase. RESULTS: B: In the survey, the handling of biodegradable plates in general was rated worse than metal plate osteosynthesis. CONCLUSION: Fixation of fractures of the zygoma with the BioSorbFX system was simple and safe. The fixations remained stable and bony healing was uneventful. Postoperative complications were few, of a minor nature and not related to the process of biodegradation.

Conservative treatment of large cystic lesions of the mandible: a prospective study of the effect of decompression.

Our aim was to evaluate prospectively the effects of decompression as the primary treatment of large mandibular cysts, irrespective of their histological type. Twenty patients with large mandibular cysts completed treatment successfully. After a mean duration of decompression of 446 days, cysts had shrunk by a mean of 81%. Mean follow-up was 527 days after removal of the decompression stent and removal of the cyst. There were no recurrences. The advantages of this approach are simplicity, immediate gathering of information on the type of cyst with simultaneous start of treatment, low morbidity and low incidence of complications during treatment. Despite the length of the treatment, we recommend the use of decompression stents in the treatment of large mandibular cysts.

Fixation of mandibular fractures with biodegradable plates and screws.

OBJECTIVE: Little data exist regarding the use of biodegradable plates and screws for the internal fixation of human mandibular fractures. The purpose of this study was to evaluate the stability of biodegradable, self-reinforced poly-L-lactide plates and screws for the internal fixation of fractures of the human mandible. STUDY DESIGN: Twenty-two individuals (14 male, 8 female; average age, 26.3 years) with a variety of fracture patterns of the mandible underwent management with a biodegradable fixation system. After surgery, maxillomandibular fixation was applied in 3 cases. Images (panoramic radiograph, computed tomographic scan) were taken immediately after surgery and at the 4-week, 8-week, 12-week, and 24-week intervals. The follow-up period averaged 49.1 weeks (range, 22 to 78 weeks). RESULTS: Mucosal dehiscences over the resorbable devices were present in 2 patients. In 1 of these 2 cases, the material had to be replaced with titanium plates. Mucosal healing and consolidation of the fracture were normal in all other patients. CONCLUSION: Self-reinforced biodegradable osteosynthesis materials provide a reliable and sufficient alternative to conventional titanium plate systems.