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

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 mm(2) for the test and 1.676 +/- 2.551 mm(2) 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.