Vertical ridge augmentation using xenogenous bone blocks : a comparison between the flap and tunneling procedures

Abstract

Objective. Previous studies have shown that the subperiosteal tunneling procedure accelerates post-grafting healing and prevents graft exposure with minor post-operative complications because it is minimally invasive. It is conceivable that new bone formation would be greater with the tunneling procedure than with the flap procedure. This hypothesis was tested in this study by comparing new bone formation between the flap and tunneling procedures after vertical ridge augmentation using xenogenous bone blocks in a canine mandible model.Study design. Bilateral, edentulated, flat alveolar ridges were created in the mandibles of 6 mongrel dogs. After 3 months of healing, 2 Bio-Oss® blocks were placed on the edentulated ridge in each side of the mandible. The blocks in each side were randomly assigned to 1 of the following 2 surgical techniques: 1) grafting with a flap procedure (flap group) or 2) grafting with a tunneling procedure (tunneling group). Six months later, biopsy specimens of the graft sites were obtained and prepared for ground sectioning and analysis.Results. In the flap group, the newly formed bone was mostly observed in the apical portion of the block. In the tunneling group, the newly formed bone was observed not just at the base of the block but also in the more coronal regions of the graft. Some of the specimens in the tunneling group showed fairly extensive bone formation close to the top of the graft. The mean percentage of newly formed bone within the block was 15.3 ± 6.6 % in the flap group and 46.6 ± 23.4 % in the tunneling group. The difference was statistically significant. Conclusion. Based on the data presented in this study, when a tunneling procedure is used to place xenogenous bone blocks for vertical ridge augmentation, bone formation in the graft sites is significantly greater than when a flap procedure is used. Based on these results, ridge augmentation using a subperiosteal tunneling procedure with Bio-Oss® blocks might be useful for implant placement in atrophic alveolar ridges.