Survival analysis of endosseous implants in bone grafts used for the treatment of severe alveolar ridge atrophy.

PURPOSE: The aim of the current study was to evaluate the long-term results of endosseous implants placed into autogenous bone grafts in severely atrophic alveolar ridges.

PATIENTS AND METHODS: A total of 871 implants were placed in 137 patients. The success rate was determined using survival analysis, log rank tests, and a cox regression analysis.

RESULTS: Seventy-four implant failures were encountered in 23 patients. Most implants were lost because of a lack of osseointegration at the time of abutment connection or by asymptomatic loosening during the first months thereafter. The overall 1-year cumulative survival rate (CSR) was 83.4%, with a decrease to 67.8% after 5 years. The only parameter of prognostic relevance in the multivariate analysis of the whole study population was the patients' gender, with a significantly worse prognosis in female patients (5-year CSR, 62.3%). However, when the patients were divided into edentulous and partially edentulous jaws, a change was observed in the overall significance of the parameters introduced into the analysis. In edentulous patients, the maxilla appeared to over-rule all other parameters, with a 5-year cumulative survival rate of 48.8%, whereas the mandible presented a significantly higher rate of implant survival (5-year CSR, 89.3%).

CONCLUSION: This study shows a poorer success rate in females than in males, probably because of differences in the quality of the bone grafts.