RESUMO
BACKGROUND: Due to the chemical and morphological differences between primary vs. permanent teeth, the time reduction of the acid etching or acidic primer can result in higher values of bond strength. AIM: To assess through a systematic review and meta-analysis the influence of the reducing etching (acid etching or acidic primer) time on the bond strength of adhesive systems to primary dentin. DESIGN: A systematic search was carried out in 3 databases: PubMed, Web of Science and Scopus. Studies that evaluated the effect of reducing the etching time on the bond strength of adhesive systems to primary dentin were included. Meta-analyses were performed using a random-effects model, with subgroups for etch-and-rinse and self-etching adhesives, with a significance level of P < .05. The risk of bias and heterogeneity between studies (Cochrane and I2 tests) were assessed. RESULTS: Eight studies were included in the systematic review and seven in the meta-analyses. The shortening etching time did not influence the immediate dentin bond strength for etch-and-rinse (Z = 0.07, P = .95) and self-etching adhesives (Z = 0.41, P = .69). After ageing, however, the shorting etching time improved the bond strength for etch-and-rinse adhesives (Z = 2.01, P = .04). All studies presented high bias risk. CONCLUSIONS: Reducing the acid-etching time to primary dentin improves the long-term bond strength to this substrate.