Vertical bone augmentation versus 7-mm long implants in posterior atrophic mandibles: results up to 4 months after loading

Aim of this work was to evaluate whether 7-mm long implants could be a suitable alternative to longer implants placed in verti- cally augmented bone for the treatment of atrophic posterior mandibles. Sixty partially edentulous patients having 7–8 mm of residual crestal height measured on a CT scan above the mandib- ular canal received either two to three submerged 7-mm long implants (30 patients) or 10 mm or longer implants (30 patients) placed in vertically augmented bone. Three implants in three patients failed in the augmented group versus one implant in the short implant group up to the placement of the final prostheses. Consequently three prostheses versus one prosthesis could not be placed at the planned time. Four complications (dehiscence) occurred in four patients of the autogenous bone group versus none in the short implant group (no significant statistical differ- ence). In two cases a partial loss of the graft occurred. No per- manent paraesthesia of the alveolar inferior nerve occurred. Patients subjected to vertical augmentation recovered their full mental nerve sensitivity significantly later than those treated with short implants. Within the limits of this study, the early results suggest that, when the residual bone height over the mandibular canal is between 7–8 mm, 7-mm short implants might be a pref- erable choice since the treatment is faster, cheaper and associated with less morbidity than vertical bone augmentation.