Does Surgical Crown Lengthening Procedure Produce Stable Clinical Outcomes for Restorative Treatment? A Meta-Analysis

The present systematic review was designed to assess whether surgical crown lengthening (SCL) procedure produces stable clinical outcomes for restorative treatment.

Based on the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, a specific PICO question was constructed: "Does the SCL procedure produce stable clinical outcomes for restorative treatment?" Electronic databases (MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register) were searched up to December 2017. The risk of bias was assessed based on the revised recommendations of the Consolidated Standards of Reporting Trials (CONSORT) statement. Forest plots were computed reporting weighted mean difference (WMD) of outcomes and 95% confidence intervals (CI) for crown length (CL), position of gingival margin (PGM), biological width (BW), and bone level changes.

Five studies were included. The risk of bias was considered high in all studies. A high degree of heterogeneity was noticed for CL, PGM, and BW. The overall mean difference for CL (WMD = -1.84, 95% CI = -0.103 to 2.05, p = 0.076), PGM (WMD = 0.87, 95% CI = 0.12 to 1.62, p = 0.02), and BW (WMD = -0.11, 95% CI = -2.21 to 1.99, p = 0.91) were not significant at follow-up. The overall mean difference for bone level changes was significant (WMD = 1.64, 95% CI = 1.26 to 2.03, p < 0.001) at follow-up.

It remains debatable whether SCL produces gingival rebound, or re-establishes BW and changes in clinical attachment level; however, further studies with low risk of bias randomized CCTs and long-term follow-up are recommended to reliably assess the restorative outcomes of SCL.