An 18-year retrospective evaluation of glass-infiltrated alumina crowns

Objective: To evaluate the long-term performance of conventionally luted In-Ceram crowns with a maximum follow-up period of 18.6 years. Method and Materials: Eighty patients (39 females and 41 males) were treated at the University of Göttingen with a total of 272 In-Ceram restorations (163 anterior and 109 posterior). All participated in a clinical followup examination (mean observational period, 13.5 ± 3.6 years). Time-dependent crown survival (in situ criteria) and success rates (event-free restorations) were calculated according to Kaplan-Meier and analyzed in relation to the crown position (anterior vs posterior crowns) using a Cox regression model. Results: Forty-three complete failures (overall survival, 80.5%) were recorded; 73.4% remained event-free after 15 years. Of the 163 anterior restorations, 18 crowns failed (9 fractures and 9 biologic reasons), resulting in a survival rate of 87.5% after 15 years (success rate, 82.7%). The remaining complete failures (10 fractures, 8 biologic reasons, and 7 changes of treatment plan) were recorded for posterior crowns (survival rate, 68.3%; success rate, 56.9%). Cox regression revealed a significant difference in survival (P = .00523) and success rates (P = .000297) of anterior and posterior crowns. Conclusion: The survival and success rates of anterior In-Ceram crowns at 15 years are comparable to those published for metal-ceramic crowns. Significantly lower survival rates and an increased rate of complications should be expected if In-Ceram crowns are placed on premolars and molars. Chipping of the veneering material was the most frequent technical complication in the posterior area. Keywords: all-ceramic, aluminous core restorations, clinical performance, retrospective study, single crowns