Full-arch implant-supported rehabilitations: A prospective study comparing porcelain-veneered zirconia frameworks to monolithic zirconia

Objectives To evaluate the performance of two types of zirconia frameworks. Material and Methods From 2014 to 2016, in a prospective clinical trial, 150 patients were rehabilitated with 83 and 110 implant-supported, screw-retained, full-arch ceramic-veneered zirconia (PVZ) rehabilitations and monolithic zirconia with porcelain veneering limited to buccal (MZ) rehabilitations, respectively. Patients were consecutively enlisted according to pre-defined inclusion criteria and evaluated on 4 months intervals. A Kaplan-Meier estimator was adopted, and the log-rank test and Wilcoxon test used to test differences in survival and successful function in the two different groups. Results The average follow-up time (+/- SD) and implant success rate was 608.80 +/- 172.52 days with 99.53% implant success for the PVZ group and 552.63 +/- 197.57 days with 99.83% success for the MZ group. According to the Kaplan-Meier estimator, the mean cumulative survival rate at the 2-year follow-up for framework fracture, major chipping, minor chipping, or any of the former combined to occur was 0.99, 0.95, 0.93 and 0.85 for the PVZ group (n = 18) and 0.99, 0.95, 0.95 and 0.89 for the MZ group (n = 15). No significant differences were found between the two groups. Conclusions Results suggest zirconia as a suitable material for frameworks in full-arch implant-supported rehabilitations. Both groups presented a low incidence of technical complications. When comparing the two different designs, the MZ group presented a lower technical complication rate, thus presenting itself as a viable alternative for full-arch implant-supported rehabilitations. Further clinical studies with longer follow-ups (5 years) should be performed to evaluate the long-term stability of such rehabilitations.