Effect of chemical surface pretreatments on microtensile bond strength of resin composite to dentin when using universal adhesives: a systematic review of laboratory studies

Objective To evaluate the effect of different chemical pretreatments of sound dentin on the microtensile bond strength (µTBS) of resin composite to dentin. Methods A comprehensive online search was performed across four electronic databases: PubMed (Medline), Web of Science, Scopus, and the Cochrane libraries to identify relevant studies, followed by screening based on established eligibility criteria. In vitro studies examining the effect of chemical pretreatment on the microtensile bond strength of sound dentin to resin composite were included. Only English studies published from 2013 until February 10, 2026 were considered. Studies that used animal teeth, focused on carious, sclerotic, or desensitized dentin, or assessed mechanical or laser pretreatments were excluded. The protocol followed PRISMA guidelines and was registered with PROSPERO (CRD420261299181). Selected studies underwent a risk-of-bias analysis. Results A total of 17 studies met the inclusion criteria. Across the included studies, microtensile bond strength results revealed that certain chemical pretreatments can significantly enhance immediate bond strength as well as maintain long-term bond durability. Pretreatment with 50% Dimethyl Sulfoxide (DMSO), acetone wet-bonding, glutaraldehyde desensitizers, and copper-based (Cu-P) pretreatments significantly increased µTBS of the majority of dental adhesives and preserved their long-term stability. Selective dentin etching (SDE) for 3 seconds, along with glycolic acid and zirconium oxynitrate (ZON) etchants, yielded significantly higher immediate bond strengths than traditional 15-second phosphoric acid etching. In cases of blood contamination, grape seed extract and hesperidin collagen cross-linkers restored bond strength to nearly uncontaminated control levels. Conversely, silver-based solutions significantly reduced µTBS, and limonene had no significant effect on bond strength. Conclusion Several chemical pretreatments, including selective dentin etching, solvent-based pretreatments, copper-based (Cu-P) pretreatments, glutaraldehyde desensitizers, and collagen cross-linkers, enhanced the bond strength of universal adhesives to sound dentin.