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.

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.

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.

Treatment of atrophic mandibular fractures based on the degree of atrophy--experience with different plating systems: a retrospective study.

PURPOSE: The aim of this retrospective study was to evaluate the clinical outcome of fractures of the atrophic mandible based on the degree of atrophy and treatment by different plating systems. PATIENTS AND METHODS: Thirty patients with 40 fractures of atrophic mandibles were treated by open reduction and internal fixation at our department between 1994 and 2001. Twelve fractures occurred in Class I (between 15- and 20-mm bone height), 10 fractures in Class II (between 10 and 15 mm), and 18 fractures in Class III atrophy (<10 mm). The profile heights of plating systems used for stabilization varied from 0.5 to 2.2 mm and were applied with an intraoral (n = 37) and extraoral (n = 3) approach. RESULTS: In 36 fractures, bone healing was uneventful. Major complications (loose hardware or nonunion) occurred in 4 fractures: 2 in Class II and 2 in Class III atrophy. Major complications were observed with 1.4-mm (n = 3) and 2.2-mm (n = 1) plates. Minor complications (infections or dehiscence) were observed in 6 fractures: 3 in Class II and 3 in Class III atrophy. Hypesthesia of the inferior alveolar nerve was present 1 week and 1 year postoperatively in 39 and 16 fractures, respectively. CONCLUSIONS: Treatment of atrophic mandible fractures should be based on the degree of atrophy. More rigid fixation may be necessary in mandibles with less than 15 mm bone height.

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.

Stability of biodegradable implants in treatment of mandibular fractures.

BACKGROUND: Biodegradable implants have not been used on a large scale for internal fixation of mandibular fractures because of presumed inferior mechanical properties. This prospective clinical trial was designed to elucidate the stability and biocompatibility of self-reinforced poly-L/D-lactide plates and screws used to stabilize a variety of mandible fractures by open reduction and internal fixation. METHODS: Sixty-six consecutive patients (22 female, 44 male; mean age, 23.9 years) with a total of 89 fractures at various sites of the mandible were included in the study. Stability of plates and screws and bone healing were observed by clinical and radiographic assessment. Intermaxillary fixation was applied in eight patients with concomitant condylar fractures for 2 to 3 weeks. RESULTS: The self-reinforcement technique provided sufficient mechanical stability of the implants for primary healing of these high-load mandibular bone areas. Postoperative complications were transient and limited to wound dehiscence and localized wound infection (two patients). In some patients, hypesthesia (three patients) or slight pain (10 patients) was reported at the 1-year recall examination, but implant-related serious adverse tissue reactions were not observed during the follow-up (mean, 24.4 months; range 6.4 to 44.3 months). CONCLUSIONS: On the basis of these preliminary results, the authors conclude that biodegradable self-reinforced implants show efficient stability during initial bone healing and promise a high potential for successful use in osteofixation of mandibular fractures.

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.

Analysis of cell-seeded 3-dimensional bone constructs manufactured in vitro with hydroxyapatite granules obtained from red algae.

PURPOSE: Bone tissue engineering is a promising approach for the treatment of defective or lost bone in the maxillofacial region. Biocompatible and biodegradable scaffolds seeded with living cells are used to create functional tissue for load-bearing bone reconstruction. The aim of this study was to manufacture cell-seeded 3-dimensional bone constructs based on hydroxyapatite ceramic granule calcified from red algae and mesenchymal cambial-layer precursor cells. The ability of these cells to grow on hydroxyapatite ceramic was quantitatively investigated to evaluate 3-dimensional bone constructs for their potential use in bone tissue engineering. MATERIALS AND METHODS: Mesenchymal cambial-layer precursor cells were isolated from mandibular periosteum biopsy samples of 3 patients. To manufacture 72 bone constructs, these cells and hydroxyapatite ceramic granules (C GRAFT/Algipore; Clinician's Preference LLC, Golden, CO) were cultivated under osteogenic differentiation conditions in a rotating wall vessel system. After 6 and 21 days, histologic examination and scanning electron microscopy were performed. The absolute DNA content, protein synthesis, and alkaline phosphatase activity were also quantified. The osteoblastic phenotype of the constructs was confirmed by the expression of bone-specific genes (osteocalcin, osteonectin, osteopontin, and core binding factor alpha1) using semiquantitative reverse transcription-polymerase chain reaction and Western blot analysis. RESULTS: Cells within the constructs showed good viability, which was evidenced by an increase in DNA content over the culture period. The decrease in alkaline phosphatase-specific activity could be an indicator of the maturation of cells and the induction of mineralization. The osteoblastic phenotype of the constructs was demonstrated on protein and at the RNA level over the entire culture period. CONCLUSION: We observed a positive effect of hydroxyapatite ceramic granules on mesenchymal cambial-layer precursor cell behavior in cell-seeded 3-dimensional bone constructs, indicating the potential applicability of C GRAFT/Algipore composites in bone tissue engineering.

Van Der Woude syndrome: variable penetrance of a novel mutation (p.Arg 84Gly) of the IRF6 gene in a Turkish family.

Van der Woude syndrome (VWS) is an autosomal dominant disorder characterized by clefts of the lip and/or palate (CL+/-P), lip pits, bifid uvula and hypodontia. Mutations of the interferon regulatory factor 6 gene (IRF6) have been recently described in patients with VWS. The entire 9 exons of the IRF6 gene in two brothers of Turkish origin clinically diagnosed with Van der Woude syndrome and four healthy family members were screened for mutations using a newly established denaturing gradient gel electrophoresis (DGGE) method. A novel heterozygous mutation in exon 2 (DNA binding region) of the IRF6 gene, p.Arg84Gly, was found in both brothers with VWS and in their clinically asymptomatic mother. Our results suggest a dominant negative effect of the p.Arg84Gly mutation in the VWS of both patients. Non-penetrance of this mutation is suggested in the mother of the patients.