Zirconia versus Titanium Implants: 1-year Prosthetic Outcome of Screw-Retained Single Crowns in a Randomized Clinical Trial.

Abstract

To compare one-year prosthetic, technical, and esthetic outcomes of screw-retained, implant-supported all-ceramic single crowns placed on two-piece zirconia (ZrO₂) versus titanium implants. In this randomized, prospective, multicenter clinical trial, patients received screw-retained, implant-supported all-ceramic single crowns placed either on a two-piece zirconia implant with a titanium base connection or on a titanium implant with a conventional titanium base (implant diameters: 4.1 mm). Restoration survival and technical complications were systematically recorded. Peri-implant soft-tissue parameters, including plaque index (PI), papilla bleeding index (PBI), and papilla index (PaI), were assessed at baseline and at the one-year follow-up. Baseline was set at three weeks after crown insertion. Statistical analyses were performed using descriptive statistics. Chi-square tests were used to compare outcomes between the zirconia and titanium implant groups, with the level of significance set at p < 0.05. A total of 117 implants were restored, and 112 restorations were available for analysis after one year of function. Restoration survival was 100% in both the zirconia and titanium implant groups. No statistically significant differences were observed between groups with regard to overall technical complication rates. Veneered zirconia crowns exhibited significantly higher complication rates compared with monolithic restorations, irrespective of the supporting implant material. Peri-implant soft-tissue parameters, including PI, PBI, and PaI, did not differ significantly between groups. Within the limitations of this prospective randomized clinical trial, restorations supported by zirconia implants with a screw-retained titanium base connection demonstrated short-term clinical performance comparable to that of restorations placed on titanium implants. Both groups showed a 100% restoration survival rate, with no significant differences in technical complications or peri-implant soft-tissue parameters. These findings should be interpreted considering the one-year follow-up, the study design primarily powered to detect differences in marginal bone loss, and the exclusive use of regular-diameter implants. Overall, the results support the favorable short-term clinical performance at 1 year. The study is registered at the German Clinical Trial Register (https://drks.de/search/de/trial/DRKS00013209) as well as at the Federal Office of Public Health's (FOPH) portal for human research in Switzerland (kofam.ch).