Influence of supracrestal tissue attachment thickness on radiographic bone level around dental implants: A systematic review and meta-analysis

The present systematic review and meta-analysis was carried out to determine the extent to which supracrestal tissue attachment (STA) thickness affects marginal bone loss (MBL) around dental implants. An electronic search was conducted in PubMed (MEDLINE), EMBASE, and complementary sources covering the period up to June 2018. The studies were meta-analyzed based on implant position with respect to the alveolar bone crest (crestal/supracrestal). The MBL values were categorized according to STA width (thick/thin). Of the 1062 eligible titles, nine articles were included in the review. The implants were positioned crestal or supracrestal with respect to the alveolar ridge. The difference between (thin/thick) STA was statistically significant among analytical subsets in terms of lesser MBL (crestal-positioned: weighted mean difference [WMD] = 0.52, 95% CI [0.03-1.01]; P = 0.036; supracrestal-positioned: WMD = 1.26; 95% CI [1.12-1.39]; P = 0.00; pooled analysis: WMD = 0.73; 95% CI [0.033-1.13]; P < 0.01). Implant positioning and patient age showed statistical significance in the meta-regression analysis. The heterogeneity explained by age was R-2 = 39.8%. Despite its limitations, the present study demonstrates that implants with thin STA result in greater MBL. There is moderate certainty of the evidence for a large effect of MBL prevention in favor of a thick STA environment in crestal-positioned implants and the pooled analysis, but lesser certainty when only supracrestal-positioned implants are considered. No trials studying this topic in subcrestal-positioned implants were found.