Clinical evaluation of 121 lithium disilicate all-ceramic crowns up to 9 years

Objective: The aim of this prospective clinical study was to evaluate the clinical performance of lithium disilicate allceramic crowns for a period from 12 to 156 months. Method and Materials: One hundred and twenty five lithium disilicate all-ceramic crowns were placed in 35 patients between 2001 and 2007. One patient who received four all-ceramic crowns was excluded from the study. The remaining 34 patients received 121 all-ceramic crowns and were recalled. Ninety-eight anterior and 23 posterior crowns were inserted. All crowns were applied on vital teeth except for 11 crowns which were placed on endodontically treated teeth. Follow-up appointments were performed 6 months after insertion, then annually. Replacement of a restoration was defined as failure. Marginal integrity, marginal discoloration, secondary caries, sensitivity, color match, and ceramic surface were evaluated following modified California Dental Association/Ryge criteria. The survival rate of the crowns was determined using Kaplan- Meier statistical analysis and log-rank test (P = .05). Results: Ten crowns were fractured. The cumulative survival rate according to Kaplan-Meier was 87.1% after mean 104.6 months (range 12 to 156 months). Location (anterior vs posterior) of all-ceramic crown did not significantly affect the survival rate according to log-rank test (P = .89). Endodontically treated teeth without post-and-core restorations exhibited a higher failure rate after all-ceramic crown application according to log-rank test (P .001). Conclusion: In this in vivo study, lithium disilicate all-ceramic crowns exhibited a satisfactory clinical performance with an estimated survival probability of 87.1% over 104.6 months and they can be used clinically in the anterior and posterior region. Restoring endodontically treated teeth with post-and-core restorations should be considered before all-ceramic crown application. Keywords: adhesive luting, all-ceramic crowns, clinical study