All-ceramic single crowns supported by zirconia implants: 5-year results of a prospective multicenter study

To assess survival/success rates and patient-reported outcome of zirconia-based posterior single crowns (SCs) supported by zirconia implants in a prospective two-center study after five years of observation.

Forty-five patients were restored with 45 zirconia implant-supported posterior SCs composed of zirconia frameworks hand-layered with a leucite-reinforced feldspathic ceramic. Survival rates of SCs were assessed and technical success was evaluated according to modified United States Public Health Care (USPHS) criteria. Furthermore, patient-reported outcome measures (PROMs) were assessed by applying visual analog scales (VAS). Wilcoxon matched-pairs signed-rank test, mixed-effects ordered logistic regression, and linear mixed models were used to evaluate time effects on response variables.

Forty patients were available after a mean observation period of 61.0 ± 1.4 months. One SC had to be replaced, resulting in a Kaplan-Meier (KM) survival estimate for the SCs of 97.5 ± 2.47%. Since nine reconstructions showed at least in one category a major deviation from the ideal (five major chippings, four with increased occlusal roughness, one significant crevice, and one pronounced over-contouring), the KM success estimate was 79.3 ± 5.8%. Incidence of chipping (n = 19) and occlusal roughness (n = 35) was frequent (p < 0.001). All PROMs at prosthetic delivery except for speech (p = 0.139) showed significantly improved VAS scores (81%-94%; p < 0.001) compared to pre-treatment evaluations. Thereafter, no decrease in satisfaction could be observed until the 5-year follow-up (93%-97%).

Veneered zirconia-based SCs supported by zirconia implants showed high survival rates and highly satisfied patients' needs. However, significant incidence of technical complications is compromising the clinical long-term outcome for this indication.