International Journal of Oral Implantology, 01/2009

Purpose: To evaluate whether 7-mm-long implants could be a suitable alternative to longer implants placed in vertically augmented bone for the treatment of atrophic posterior mandibles. Materials and methods: Sixty partially edentulous patients having 7 to 8 mm of residual crestal height and at least 5.5 mm thickness measured on a computed tomography scan above the mandibular canal were randomised to receive either two to three submerged 7-mm-long NanoTite External Hex implants (Biomet 3i) or 10-mm or longer implants (30 patients per group) placed in vertically augmented bone. Bone was augmented with anorganic bovine bone blocks (Bio-Oss) using a sandwich technique and resorbable barriers. The grafts were left healing for 5 months before placing the implants, which were submerged. Four months after implant placement, provisional acrylic prostheses were delivered. Definitive screw-retained metal-ceramic prostheses were delivered 4 months later. Outcome measures were: prosthesis and implant failures, any complications, and time needed to fully recover mental nerve sensitivity. All patients were followed up to the delivery of the final restorations (4 months after loading). Results: No patient dropped out. In two patients of the augmented group, there was not enough space to place 10-mm or longer implants as planned and 7-mm-long implants were used instead. The most likely reason for this is that the Bio-Oss blocks fractured in many pieces at placement. One prosthesis could not be placed when planned in the 7-mm group versus three prostheses in the augmented group, because of failure of one implant in each patient. The difference was not statistically significant. All implants were successfully replaced and final prostheses delivered. Four complications (wound dehiscence) occurred during graft healing in the augmented group (one possibly associated with the failure of one implant) versus none in the 7-mm-long implant group. The difference was not statistically significant. No patient suffered from permanent paraesthesia of the alveolar inferior nerve; however, sensitivity was recovered significantly faster in the short implant group. Conclusions: The early results of this study suggest that, when the residual bone height over the mandibular canal is between 7 and 8 mm, 7-mm short implants might be a preferable choice since the treatment is faster, cheaper and associated with less morbidity than vertical bone augmentation. These preliminary results must be confirmed by follow-ups of 5 years or more in order to monitor the performance of short implants over time. Keywords: bone augmentation, bovine anorganic bone, inlay graft, short dental implants, vertical augmentation

Purpose: To evaluate the efficacy of 10- to 16-mm-long implants inserted in maxillary sinuses augmented according to a lateral approach technique with 50% particulated autogenous bone harvested from the oral cavity and 50% Bio-Oss, versus 8-mm-long hydroxyapatite-coated implants placed in crestally augmented sinuses with autogenous bone according to the Cosci technique. All implants were early loaded at 45 days after placement. Materials and methods: Forty partially or fully edentulous patients having 3 to 6 mm of residual crestal height and at least 4 mm thickness below the maxillary sinuses (measured on a CT scan) were randomised to receive one to three, 10- to 16-mm-long implants (20 patients) after lateral sinus lifting with 50% anorganic bovine (Bio-Oss) and 50% autogenous bone, or 8-mm-long implants (20 patients) after crestal sinus lifting with autogenous bone. Implants were submerged and left to heal for 45 days. Within 1 week of abutment connection, implants were loaded with screw-retained full acrylic provisional prostheses. Definitive metal-ceramic prostheses were provisionally cemented 45 days after abutment connection. Outcome measures were the number of prosthesis and implant failures, and any complications. In addition, the stability of individual implants was assessed with Osstell and Periotest at abutment connection (baseline) and after 1 year of loading by a blinded outcome assessor. All patients were followed up for 1 year after loading. Results: No patient dropped out. In three patients of the 8-mm implant group, primary stability could not be initially obtained. However, after immediately replacing the unstable implants with implants with a larger diameter, sufficient primary stability was obtained. One implant failed in the short implant group and five implants failed in three patients of the longer implant group. The difference was not statistically significant. There were no differences in complications between groups. However, two major post-operative complications occurred in the longer implant group: one abscess and one sinusitis, which determined the complete failure of the treatment in two patients (4 implants lost). Osstell values increased, whereas Periotest valves decreased over time, and there were no differences between groups at any time point. Conclusions: This study suggests that in atrophic maxillary sinuses with a residual height of 3 to 6 mm, it may not be necessary to perform lateral sinus lifting to place longer implants (10 to 16 mm); 8-mm short implants might be a preferable choice as the treatment appears to be associated with less morbidity. This study also suggests that it is possible to load early (at about 7 weeks) implants placed in lifted sinuses that achieved a sufficient primary stability at placement. These preliminary results must be confirmed by larger trials with follow-ups of 5 years or more to monitor the performance of short implants over time. Keywords: bone augmentation, bovine anorganic bone, early loading, short dental implants, sinus lift

Purpose: To evaluate the efficacy of Emdogain versus placebo (its carrier) for the treatment of deep infrabony defects. Materials and methods: Thirty patients with an infrabony defect of at least 4 mm deep and at least 2 mm wide were randomly allocated for treatment with either Emdogain or placebo (the Emdogain carrier). The treating clinician was completely blinded to the therapy provided and performed all evaluations blindly up to the third year of follow-up. Outcome measures were tooth loss, complications, post-operative healing, patient's satisfaction with treatment and aesthetics, changes in probing attachment levels (PAL), probing pocket depths (PPD), gingival recessions (REC) and radiographic bone levels (RAD). Results: One year after treatment, both therapies had significantly improved clinical outcome measures: placebo group PAL gain = 3.3 mm, PPD reduction = 3.9 mm, and RAD gain = 2.5 mm; Emdogain group PAL gain = 3.4 mm, PPD reduction = 4.2 mm, and RAD gain = 2.5 mm. Both therapies induced statistically significant gingival recession (0.6 mm in the placebo and 0.8 mm in the Emdogain group). There were no statistically significant differences between groups for any of the outcomes tested. No teeth had to be extracted up to 3 years after treatment. Conclusions: There does not appear to be any clinical advantage when using Emdogain over its carrier (placebo) in the treatment of deep and wide infrabony defects. Keywords: Emdogain, infrabony defect, periodontitis, randomised controlled clinical trial

Purpose: To present clinical results of an implant placement protocol using 4 or 6 implants supporting immediately loaded fixed prostheses. Materials and methods: This retrospective clinical study included 20 patients (restoring 19 maxillae and 9 mandibles) with 127 loaded implants that supported immediately fixed complete-arch acrylic prostheses followed for at least 2 years. Outcome measures were failures of the prosthesis and of the implants, an approximate radiographic evaluation, and any complication. Results: A total of 116 implants were immediately loaded. Eleven implants were not immediately loaded because they did not reach the planned insertion torque. These implants were loaded after the osseointegration period when the final prostheses were delivered. Four implants failed during the osseointegration period and all of them were successfully replaced. The survival rate was 96.9% (96.7% in the maxilla and 97.2% in the mandible). No prosthesis was lost. Eight patients experienced fractures of their provisional prosthesis that were repaired in the clinic. Seven implants out of 127 experienced marginal bone loss up to the first and the second thread. Conclusions: The results indicate that the 'all on four' and 'all on six' immediate-function concept postextraction could be a viable and predictable treatment. Keywords: fresh extraction sites, full edentulism, immediate loading

This section presents concise educational articles for practising dentists. The series aims to educate practitioners regarding statistics and methods of conducting and interpreting research. Keywords: forest plot, meta-analysis, randomised clinical trials