Tomographic analysis of volumetric fresh frozen allograft in the posterior mandible

Abstract

Residual bone ridge atrophy in the posterior mandible is one of the most challenging conditions for the surgeon regarding the reconstruction and installation of dental implants. Several techniques and materials have been proposed and studied to try to solve this problem such as only autografts, interposition autografts, bone distraction, lateralization of the lower alveolar bundle, and use of short implants among others. Each technique has its limitations and different morbidity levels. In cases of extreme atrophy, when the residual ridge height is lower than 5 mm, it is impracticable to install short implants, perform bone distraction or interposition grafts. In these clinical situations, the more traditional ways of rehabilitation are nerve lateralization or autogenous grafting with autogenous blocks, usually harvested from the iliac crest. Both techniques have some disadvantages for the patient and increase the surgical time. Alternatively, grafting with allogenous fresh frozen bone has gained importance in recent years both due to the amount of bone available, and to avoid the harvesting of the autograft. Other advantages of using this modality of graft are the reduction of surgical time, simplicity of work, and decreased trans and postoperative morbidity to the patient. The literature reports few studies about the fresh frozen bone allograft incorporation to extremely atrophic mandibular ridges, its volume maintenance, and bone quality. Objective: the aim of the study is to evaluate clinical, histological, histomorfometrical, and tomographically the behavior of fresh frozen bone allograft when applied in an unusual technique to increase bone ridge in the atrophic posterior mandible as well the osseointegration of the implant in the graft area. Materials and Methods: Fifteen Hemi-mandibles of patients presenting critical alveolar atrophy will be 3-D reconstructed using allograft fresh frozen bone block, fixed with titanium screws, and covered with mineral bovine bone particulate (Bio-Oss®) and collagen membrane (BioGide®). After six months, implants will be installed. CT cone beam scans will be taken both at immediate postoperative bone grafting and pre-operative surgery for implant placement, in order to perform volume and linear analysis. The primary stability of the implants will be measured by torque, and their osseointegration evaluated until the prosthetic rehabilitation is concluded. The results will be analyzed through ANOVA. (AU)