ABSTRACT
OBJECTIVES: The presence of insufficient peri-implant supracrestal tissue height (STH) may increase marginal bone resorption. This study aims to evaluate the effect of STH on marginal bone level changes (ΔMBC) in platform-switched posterior implants placed crestally and subcrestally. METHODS: A total of 80 implants were included in this study. There were two main groups in the study; STH≤2 mm (A) and STH> 2 mm (B) and four subgroups according to the implant placement level, crestally (I) and subcrestally (II): A-I, A-II, B-I, and B-II. Intraoperatively, STH and placement depths of implants were measured from mesial and distal aspects. The mesial and distal peri-implant marginal bone levels were measured on periapical radiographs at immediately (T0), 6 months (T1), 9 months (T2), and 12 months (T3) after functional loading, and the difference between the marginal bone levels was calculated as the ΔMBC. RESULTS: Statistically significantly more mesial ΔMBC was detected in the A-I than in the B-I at the time of T0-T1. In the group with STH greater than 2 mm, the difference in ΔMBC between the crestally and subcrestally placements was not statistically significant. CONCLUSIONS: This study was found that STH is effective at protecting the marginal bone in the early period, and in cases where the STH is insufficient, subcrestally placement may increase long-term implant success by preventing marginal bone loss from occurring beyond the implant shoulder. The clinical trial number is NCT05595746. CLINICAL SIGNIFICANCE: In this study, it was demonstrated that an STH greater than 2 mm is important for marginal bone stabilization, regardless of crestal and subcrestal levels, and that subcrestally placement is beneficial in cases of insufficient STH.
