Effect of chlorhexidine pretreatment on clinical performance of adhesive restorations: a systematic review and meta-analysis.

STATEMENT OF PROBLEM: The long-term stability of resin-dentin adhesion remains a major concern in restorative dentistry. Hydrolytic and enzymatic degradation of the hybrid layer contributes to the deterioration of resin-bonded restorations. Inhibition of matrix metalloproteinases (MMPs) by chlorhexidine digluconate (CHX) has been proposed to preserve the hybrid layer and improve adhesive durability. PURPOSE: This systematic review and meta-analysis evaluated the effect of dentin pretreatment with CHX on the clinical performance and longevity of resin-based restorations compared with no CHX application. MATERIAL AND METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, electronic searches were conducted in PubMed, Scopus, Web of Science, and the Cochrane Library up to September 2025. Randomized and non-randomized clinical trials assessing CHX pretreatment before adhesive application were included. Primary outcomes were restoration retention, postoperative sensitivity, and secondary caries after ≥6 months of follow-up. Data extraction and risk of bias assessment were performed independently using the Cochrane RoB 2.0 tool. Random-effects meta-analyses were performed using risk differences (RDs) with 95% confidence intervals (CIs). RESULTS: Eleven clinical trials (6 months-4 years of follow-up) met the inclusion criteria. CHX concentrations ranged from 0.2% to 2% with application times of 15-30 s. Most studies used etch-and-rinse adhesives. Pooled analyses showed no significant differences between CHX and control groups for restoration retention (RD = 0.01; 95% CI, -0.02 to 0.04; p = .53), postoperative sensitivity (RD = 0.01; 95% CI, -0.04 to 0.06; p = .67), or secondary caries (RD = -0.00; 95% CI, -0.03 to 0.03; p = .80), with no heterogeneity (I2 = 0%). CONCLUSIONS: Although CHX demonstrates MMPs inhibition in vitro, current clinical evidence does not support its routine use for enhancing the longevity of resin-dentin bonds, particularly with etch-and-rinse adhesive systems. CHX may still be useful for antimicrobial purposes or in high-caries-risk patients. Further standardized, long-term randomized clinical trials are warranted to clarify its potential benefits with self-etch and universal adhesives. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD420251165239.