Clinical Evaluation of All-Ceramic Aluminous Core Single Crowns: 15-Year Results

Objective: Recent studies demonstrated survival rates of all-ceramic single crowns only on mid-time base up to 5 years of clinical observation time. Glass-infiltrated aluminous core restorations (In-Ceram) have been applied already since 20 years. The purpose of this study was to evaluate the long-term clinical performance of In-Ceram single crowns in the anterior and posterior region of the oral cavity. The null-hypothesis was the localization has no influence on the clinical survival or success rates. Methods: 265 aluminous core all-ceramic single crowns were included in the study (159 inserted on anterior teeth, 106 inserted on posterior teeth). 76 patients (38 female/38 male) participated in a clinical follow-up examination after a mean observation period of 12.8 (±3.4) years. Time-dependent survival (in-situ criteria) and success rates (event-free-restorations) were calculated according to Kaplan Meier. The survival and success rates were analyzed in relation to the crown position (anterior vs. posterior crowns) using the log-rank test. Results: Regarding the in-situ criterion 46 failures were recorded. 18 crowns got lost in the anterior region, 28 failed on premolars and molars. Main reasons were biological complications followed by fractures of the ceramics. An overall survival rate of 79.9% was determined, 88.5% for restorations in the anterior region and 65.7% for the posterior region. The success rate (event-free restorations) for anterior single crowns was 83.6%. Posterior crowns showed a success rate of 55.1% and the overall success rate was 72.0%. The Log-rank tests revealed a significant difference in survival (p=0.001) and success rates (p=0.0001) of anterior and posterior In-Ceram crowns. Conclusions: Anterior In-Ceram single crowns offer suitable long-term results regarding their clinical performance, comparable to those demonstrated for metal-ceramic crowns. Significantly lower survival rates and an increased rate of complications have to be expected if In-Ceram crowns are placed on premolars and molars.