Monolithic lithium-disilicate single crowns supported by zirconia oral implants: three-year results of a prospective cohort study.

Abstract

To determine the survival and success rate of CAD/CAM-fabricated monolithic lithium-disilicate crowns supported by zirconia oral implants after 3years. Twenty-four patients in need of a single tooth replacement received a zirconia implant and were finally restored with 24 single crowns (SCs) ground out of pre-crystallized lithium-disilicate blanks. The restorations were adhesively cemented and evaluated using modified United States Public Health Service (USPHS) criteria. In case of clinically relevant defects that could be repaired to an acceptable level, SCs were regarded as surviving. Restorations with minor chippings, a small-area roughness (ø<2mm), slightly soundable marginal gaps, minimal under-/overcontours, and tolerable color deviations (<1 Vitashade) were regarded as success. The Kaplan-Meier method and log-rank tests were used for the success/survival analyses and the calculation of potential group differences (gender, location, jaw). Additionally, several patient-reported outcome measures (PROMs) were evaluated. Twenty-three patients were seen 3years after implant placement. No SC had to be replaced, resulting in 100% survival. No chippings were observed. As one SC showed a major occlusal roughness, the Kaplan-Meier success rate after a mean observation period of 31months was 95.7%. No group differences could be calculated. Compared with the pre-treatment surveys, the further PROMs showed a permanently improved perception of function, esthetics, sense, and speech. Monolithic lithium-disilicate SCs supported by zirconia implants showed promising survival and success rates after an observation period of 3years. It remains to be seen whether the further observation period confirms this positive results.