Prospective Evaluation of Posterior Fixed Zirconia Dental Prostheses: 10-Year Clinical Results

Purpose: To investigate the clinical survival and success rates of conventionally luted three- and four-unit fixed dental prostheses (FDPs) with zirconia frameworks (Cercon Smart Ceramics, DeguDent) after a mean observation period of 119 ± 36 months. Materials and Methods: A total of 75 patients were treated in the Department of Prosthodontics at the University of Goettingen, Germany, and a total of 99 posterior FDPs were inserted and luted with zinc phosphate cement. Time-dependent survival and success rates were calculated using Kaplan- Meier curves, and their relationships with the type of veneer (ceramic), location (maxilla vs mandible), and span length (three-unit vs four-unit) were analyzed with a Cox regression model (P .05). Results: Of the 99 inserted FDPs, 24 were lost to follow-up, 51 remained functional and passed the 10-year examination (overall survival rate: 75.0%; 95% confidence interval [CI]: 0.64, 0.85), and 13 were absolute failures caused by technical events (technical survival rate: 84%; 95% CI: 0.64, 0.85). In 50 FDPs, relative failure required a clinical intervention to maintain function (overall success rate: 40%; 95% CI: 0.29, 0.52). For 35 of these FDPs, the relative failure was caused by technical events (technical success rate: 61%; 95% CI: 0.49, 0.73). None of the evaluated factors showed an association with overall or technical survival or success. Conclusion: Zirconia-based posterior FDPs produced with a first-generation computer-assisted manufacturing (CAM) system revealed high rates of absolute and relative failure, mainly due to technical events, after a mean observational period of 10 years. Further clinical studies with updated computer-assisted design (CAD)/CAM systems are needed to determine the long-term performance of zirconia-based FDPs.