Clinical evaluation of zirconia-based all-ceramic single crowns: an up to 12-year retrospective cohort study

Objectives: This study aims to investigate the incidence of clinical complications with tooth-supported zirconia-based all-ceramic single crowns and identify pertinent risk parameters. Materials and methods: A retrospective cohort study (May 2004 to April 2016) utilizing clinical records of patients receiving yttrium-oxide–partially stabilized zirconia (Y-TZP)-based all-ceramic crowns placed at Tohoku University Hospital was performed. The length of time of treatment success (complication event-free) and restoration survival (including minor complication events and remaining clinically functional) were estimated using Kaplan–Meier analysis. Multilevel survival analysis was used to identify risk factors. Results: One hundred thirty-seven crowns were evaluated (mean follow-up time, 7.0 years). A total of 21 crowns experienced at least one complication with fracture of veneering ceramic being the most common (16 crowns). Estimated success and survival rates at 5 years (96.9 and 98.5%, respectively) decreased at 10 years to 62.1 and 67.2%, respectively. The risk of complications was significantly higher for molar crowns compared to anterior crowns (p < 0.01). A significant association of complications with metal antagonist restorations was shown by univariate analysis (p < 0.01). Conclusions: Given the study limitations, Y-TZP single crowns placed on anterior teeth demonstrated encouraging clinical results over a period of up to 10 years. However, there is a substantial risk of complications with posterior teeth within 10 years of restoration placement. Clinical relevance: Treatment with zirconia-based all-ceramic crowns for molar teeth with metal antagonist occlusion should be undertaken with caution.