Layered approach with autogenous bone and bone substitute for ridge augmentation on implant dehiscence defects in dogs

Objectives: This study compared the efficacies of different layered approaches using autogenous bone and synthetic bone substitute for ridge augmentation on implant dehiscence defects in dogs. Materials and methods: Right mandibular second, third, and fourth premolars and the first molar were extracted, followed by standardized one-wall defect preparation in five dogs. After a healing period of 12 weeks, three implants (Implantium^®) were installed. Each of the three implant dehiscence defects was grafted with a different material as follows: (i) synthetic bone substitute combined with collagen (SBC; SBC group), (ii) inner autogenous bone layer and outer SBC layer (IAB group), and (iii) inner SBC layer and outer autogenous bone layer (OAB group). The grafted sites were covered with a resorbable collagen membrane. Quantitative and qualitative analyses of the subsequent bone regeneration were performed at 12 weeks postoperatively. Results: The dome-like augmented shape was relatively well maintained in the IAB and OAB groups, while the graft particles in the SBC group were dispersed. The bone-to-implant contact values tended to be significantly higher in the OAB group (49.51%) than in the SBC (36.58%) group. The amounts of newly formed bone within an area designated as 1 × 3 mm (width × height) from the implant platform in the IAB, OAB, and SBC groups were 35.59%, 28.10%, and 16.71%, respectively. Conclusion: Application of the layered approach using autogenous bone and synthetic biomaterial resulted in substantial new bone formation and volume maintenance on implant dehiscence defects, irrespective of the position of the autogenous bone layer.