A New Approach to Maintenance of Regenerated Autogenous Bone Volume: Delayed Relining with Xenograft and Resorbable Membrane

Purpose: The aim of this case series is to propose an approach to help maintain autogenous bone grafts. This is done by applying a collagen membrane (CM) and anorganic bovine bone (ABBM) at the time of implant surgery, rather than at the time of ridge augmentation, to avoid volume loss after implants are inserted. Materials and Methods: Ten patients with severe horizontal bone atrophy were consecutively enrolled in this study. A staged approach was chosen for implant placement following horizontal ridge augmentation. A block graft was harvested from the retromolar area and secured to the recipient site with fixation screws; contour overbuilding was avoided. The width of the ridge was measured before and after horizontal augmentation. After 4 months of healing, implants were inserted, the augmented site was relined with ABBM, and CM was applied to prevent bone volume loss. Another 4 months later, at the time of abutment placement, cone beam computed tomography was performed to quantify the end result. Results: The mean horizontal ridge width prior to treatment was 2.1 ± 0.5 mm. Mean postsurgical crest width was 6.9 ± 0.5 mm. After the 4-month healing period, the mean alveolar crest width was 6.6 ± 0.6 mm. At the time of abutment connection, the mean width of the regenerated ridge, as measured on three-dimensional cone beam images, was 7.7 ± 0.8 mm. Conclusions: Minimal bone loss occurred in unprotected autogenous bone grafts with respect to alveolar bone contour (0.25 ± 0.29 mm). After the implants were inserted, no further remodeling/resorption occurred with sites treated by ABBM and CM relining; moreover, an additional increase in alveolar crest width was evident. The nonresorbable ABBM osseointegrated clinically and radiologically, preventing bone loss prior to implant loading. This layer appeared to maintain the regenerated crest volume. Keywords: autogenous bone graft, bone augmentation, bone resorption, volume maintenance