Three-Second Short Dentin Etching: Systematic Review of In Vitro Evidence in Adhesive Dentistry

Short dentin etching, or selective dentin etching (SDE) for 3 s, has emerged as a potential strategy to enhance the bond strength of adhesive systems while preserving dentin integrity. This systematic review aimed to evaluate whether a 3-s SDE protocol improves bond strength and interface durability compared to other adhesive strategies, such as conventional etch-and-rinse or self-etch protocols, with or without variations in etching time or application method.

A systematic search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines across PubMed, Scopus, Scielo, Embase, and ISI Web of Science, with no restrictions on publication year. Studies included human or bovine dentin as the substrate, employed SDE for 3 s before adhesive placement, and compared bond strength outcomes using conventional etching protocols. The outcome of interest was bond strength. Two independent reviewers screened and extracted data.

Nine in vitro studies met the inclusion criteria. Evidence suggests that 3-s SDE improves immediate bond strength and, in some cases, long-term durability of universal adhesives by preserving hydroxyapatite and preventing over-demineralization of dentin. Excessive etching time (≥ 15 s) was associated with thicker, poorly infiltrated hybrid layers prone to hydrolytic degradation. The effect of SDE varied with adhesive type, presence of 2-hydroxyethyl methacrylate (HEMA), application method (with or without rubbing), solvent content, and hybrid layer composition, highlighting the importance of both material selection and etching technique.

SDE for 3 s enhances bonding performance and may increase the longevity of adhesive restorations. Clinicians should consider adhesive type, etchant viscosity, and substrate variability when applying this protocol. Future studies should explore standardized clinical protocols and long-term outcomes in vivo.