Conditions for success in guided bone regeneration: retrospective study on 376 implant sites

BACKGROUND: Used alone or in association with bone, guided bone regeneration is a clinically accepted method to increase the volume of bone during implant placement. Concerns about appropriate surgical techniques and the predictability of the results questions still exist. The aim of this study was to assess the conditions for success. METHODS: Three-hundred-seventy-six implants were placed in association with 214 non-resorbable membranes. In 109 implants, the membrane was secured on a blood clot; for 213 implants, membrane was placed with autogenous bone; and for 54 implants it was placed with allogenic bone. The surgical procedure, the primary closure, the timing of re-entry, and the density of regenerated tissue were studied. RESULTS: In 19 membranes, barrier exposure occurred before 3 months in these instances, the regenerated tissue was removed; another 7 membranes were exposed between 3 and 6 months. The 188 non-exposed membranes were removed between 6 and 12 months. In cases of exposure before 3 months, the regenerated tissue was soft and then removed. After closure for 6 months or more, the regenerated tissue was dense and resistant to probe pressure. The best results were obtained when the membranes were placed with autogenous bone. CONCLUSIONS: If all the clinical steps are appropriately followed, guided bone regeneration using an autogenous bone graft and implant placement is a predictable technique for increasing bone volume.