Does the etching strategy influence the bonding of universal adhesive systems to primary teeth? A systematic review and meta-analysis of in vitro studies

Purpose To assess through a systematic review and meta-analysis of in vitro studies, the influence of the etching strategy (etch-and-rinse versus self-etch) of universal adhesive systems on bonding to primary teeth. Methods A systematic search was carried out in PubMed, Web of Science and Scopus. In vitro studies that compared the bond strength of the etching strategies of universal adhesives to primary teeth were included. Pooled-effect estimates were derived from a random-effects model by comparing the standardized mean difference between the etching strategies (a < 0.05). The risk of bias and heterogeneity between studies were also assessed (Cochrane and 12 tests). Results Seven studies were included in the review and six in the meta-analyses. For dentin, the immediate bond strength was not influenced by the etching strategy regardless of sound (Z= 0.72, p = 0.47) or caries-affected (Z=1.27, p = 0.21) substrate, nor after aging (Z= 0.24, p = 0.81). It was not possible to perform a meta-analysis for the enamel substrate. Most studies have a medium risk of bias. Conclusions This systematic review and meta-analysis of in vitro studies provides evidence that universal adhesives can be used in both etching strategies in primary dentin. The evidence is currently insufficient about whether selective acid etching of primary enamel is necessary when universal adhesive systems are used.