Survival of single crystal sapphire implants supporting mandibular overdentures

One hundred and sixteen sapphire (Bioceram, Kyocera) implants were inserted in 30 patients between 1984 and 1991 to support mandibular overdentures. Survival analyses were made on the basis of clinical and radiographic follow-up evaluation for 15 patients with 56 implants. For the 15 patients who were lost to follow-up, 7 of whom were deceased, reviews of records and available radiographs determined outcome and observation time. The resulting Kaplan-Meier cumulative survival rate for the sapphire implants was 68.66%, mean survival time 11.44 years, 95% confidence interval 10.56-12.32 years. Uni- and multivariate analysis using the Cox Regression model, indicated an increased risk of implant failure in patients over 60 years at time of operation, and in patients who smoke. Limited experience in implant surgery were associated with increased implant failure rate. A qualitative analysis of survived implants showed a mean annual bone loss of 0.2 mm, moderate to excellent plaque control, and excellent to good subjective global assessment of the treatment. The long-term results of the sapphire implant system used for mandibular overdenture support are inferior to other implants systems.