Three-year clinical performance of different monolithic single CAD/CAM crowns. A randomized controlled clinical trial.

Abstract

Aim: The objective of the present study was to evaluate the survival rate and clinical performance of three CAD/CAM materials used for the fabrication of monolithic single crowns: lithium disilicate glass-ceramic (LiSi); feldspathic ceramic (FC); and polymer-infiltrated ceramic network (PICN).

Materials and methods: Fifty patients requiring a maxillary or mandibular posterior single crown were included in the present prospective randomized controlled clinical trial. Patients were randomly assigned to one of three study groups (LiSi, FC, PICN). The primary outcome was survival; the secondary outcomes were biologic and technical parameters as well as modified-USPHS (mUSPHS, United States Public Health Service) criteria. Outcomes were assessed after crown insertion at baseline (BL) and at a 1- and 3-year follow-up (1y-FU, 3y-FU). Statistical analysis included descriptive statistics and Kaplan-Meier curves, with the log-rank test for survival and the Kruskal-Wallis test for the comparison of biologic and technical parameters.

Results: At the 3y-FU, the survival rate was 100% for both LiSi and PICN crowns, while FC crowns exhibited a significantly lower survival of 76.9% (P = 0.039). The failures in the FC group were attributed to three complete crown fractures. Regarding the secondary outcomes, PICN crowns showed significantly more plaque accumulation than FC and LiSi crowns after 1 and 3 years.

Conclusions: Monolithic single crowns fabricated using CAD/CAM techniques, specifically in LiSi and PICN, demonstrated high survival rates at the 3y-FU. However, crowns made of FC showed a higher rate of both minor and catastrophic fractures. Therefore, the use of FC may not be recommended for single posterior crowns, especially when restoring teeth with reduced tooth substance.

Clinical implications: The present study highlights the clinical superiority of LiSi and PICN over FC for single crowns in the posterior region, with LiSi and PICN showing significantly higher 3-year survival rates.