Implants in the posterior atrophic mandible
Part 1 -The rehabilitation of the partially edentulous posterior mandible is a common clinical problem. The ideal solution would be an implant-supported fixed prosthesis. The main obstacle associated with this treatment option is the lack of sufficient bone height. As a consequence the ideal approach would be to augment the bone vertically in a predictable and successful way. A possible approach is to use an interpositional bone graft. Horizontal osteotomy with the interposition of bone in the form of a “sandwich” involves raising a coronal osteotomised segment of the mandible, which is still attached to the lingual periosteum, and interpositioning of a bone block graft. This technique offers the advantage of guaranteeing a greater vascular supply, coming from the lingual periosteum and from the residual bone, to the inlay graft; it also allows optimum use of the native basal bone, which should be less prone to resorption. Frequently, the interpositional technique was associated with autologous bone harvesting which involves discomfort and post-surgical morbidity, however data show that heterologous bone blocks in the inlay technique are similar in results to autogenous bone blocks. The use of heterologous bone blocks allows avoiding grafting with significant patient discomfort, postoperative morbidity and complications. Hence, the interpositional technique with its latest development in the posterior atrophic mandible rehabilitation can be considered a reliable solution that allows an increase in bone height sufficient for implant placement quite stable over time avoiding for autogenous bone harvesting.
Part 2 - Implant therapy is a recognized treatment for edentulous areas with long term success. Nevertheless, in some critical situations we must use different techniques of advanced oral surgery and/or bone regeneration to allow the implant placement avoiding the damage of important anatomical structures, like the inferior alveolar nerve (IAN). In severe cases of posterior mandible atrophy we must use specific techniques to solve the problem, like short or tilted implants ( on the anterior zone) or even more advanced techniques like nerve transposition, trespass and lateralization in the posterior atrophic mandible.