Micro-shear bond strength of universal adhesives to dental enamel: a systematic review and meta-analysis

Despite manufacturers' efforts to develop and commercialize new universal adhesives, it remains to be clarified which bonding strategy favors adhesion to tooth enamel. A systematic review was conducted to determine whether the etch-and-rinse or self-etching mode is the best protocol for enamel adhesion by universal adhesives.This work followed the PRISMA guideline and a total of 8 articles were included in the meta-analysis. Two reviewers performed a bibliographic search until June 2020 in four databases: Pubmed, Cochrane Library, Web of Science and Embase. In vitro studies, which evaluated the bond strength using the universal adhesive micro-shear test applied to the enamel by means of etch-and-rinse and self-etching were eligible for selection. Statistical analyzes were performed using the RevMan 5.4 program. A global comparison was performed with random effects models at a significance level of p <0.05.The results showed that the etch-and-rinsemode improves the bond strength to microcutting in theenamelcomparedtothe self etchingmode (p≤0.05). Based on this meta-analysis, it is concluded that prior enamel etching can be considered the best strategy to optimize the bond strength of universal adhesives and that this strategy would be advisable to optimize adhesion.