Influence of different mucosal phenotype on early and long-term marginal bone loss around implants: a systematic review and meta-analysis

Objectives To investigate the influence of different mucosal phenotypes on peri-implant marginal bone loss. Materials and methods The search was conducted in five databases including PubMed, Embase, Cochrane, Scopus, and Web of Science (until 1st Sept. 2022) to identify relevant clinical studies. Potentially relevant journals were also manually searched. Two reviewers independently screened studies, extracted data, and evaluated the quality of the studies. Prospective clinical trials and observational studies investigating peri-implant marginal bone loss in thick-mucosa and thin-mucosa groups were included. Results A total of 14 studies were included in this systematic review. Results of the meta-analysis revealed a weighted mean difference of 0.38 mm for marginal bone loss between thick- and thin-mucosa groups (95% confidence interval = 0.02-0.74, P = 0.002). Statistical significance existed in short-term (follow-up <= 1 year) data ( WMD = 0.41 mm, 95%CI = 0.11-0.70, P = 0.007), but not in long term (follow-up >= 3 y) data ( WMD = 0.17 mm, 95%CI = - 0.02-0.36, P = 0.07). Survival rate revealed no difference between thick and thin mucosa groups. In subgroup analyses, a positive association between thick mucosa and less marginal bone loss was found in the non-submerged group, cement-retained group, and bone-level group. Conclusions A significantly less marginal bone loss occurred in implants with thick mucosa than with thin mucosa in the short term, whereas no significant difference was observed in the long term. Due to the substantial heterogeneity and limited long-term data, further high-quality evidence is warranted to confirm the results.