Clinical evaluation and quantitative occlusal change analysis of posterior implant-supported all-ceramic crowns: A 3-year randomized controlled clinical trial

Abstract

Objectives: To compare the survival and complication rates of posterior screw-retained monolithic lithium disilicate (LS₂ )/veneered zirconia (ZrO₂ ) single implant crowns (SICs), as well as analyze the occlusal changes observed during a 3-year follow-up period.

Materials and methods: Thirty-three patients were included and randomly divided into two groups. The test group consisted of 17 patients who received monolithic-LS₂ -SIC, while the control group consisted of 16 patients who received veneered-ZrO₂ -SIC. Implant/prosthesis survival rates, technical complications, peri-implant soft tissue conditions, and quantitative occlusal changes of SIC (obtained by the intra-oral scanner and analyzed in reverse software Geomagic Control 2015) were assessed at 1- and 3-year follow-ups. Bone loss and Functional Implant Prosthodontic Score (FIPS) were evaluated at a 3-year follow-up.

Results: After a 3-year follow-up period, one patient dropped out of the follow-up. No implant loss was observed. One crown was fractured, resulting in prosthesis survival rates of 93.75% for the monolithic group and 100% for the veneered group. A technical complication rate of 25% (4/16) was observed in the veneered group (p = .333). No significant differences in the marginal bone loss were observed at the 3-year follow-up (0.00 (-0.22, 0.17) mm versus 0.00 (-0.12, 0.12) mm, p = .956). The total FIPS scores for the test group were 9.0 (9.0, 9.0), while the control group received scores of 9.0 (8.0, 10.0) (p = .953). The changes in mean occlusal clearance were 0.022 ± 0.083 mm for the test and 0.034 ± 0.077 mm for the control group (at 3 years, p = .497). The changes in occlusal contact area were 1.075 ± 2.575 mm² for the test and 1.676 ± 2.551 mm² for the control group (at 3 years, p = .873).

Conclusion: After a 3-year follow-up, screw-retained monolithic LS₂ and veneered ZrO₂ SIC demonstrated similar survival rates. The occlusal performance of implant prostheses needs to be closely examined during follow-up, and appropriate occlusal adjustments need to be considered.

Keywords: complications; digital workflow; implant crown; monolithic; occlusal; screw-retained; survival; veneered.