Purpose: To evaluate the effect of crosslinking agents combined with dimethyl sulfoxide (DMSO) on collagen crosslinking, long-term bond strength and interfacial integrity of a universal adhesive applied to eroded dentine.

Methods: Eighty human molars were randomly distributed into 10 groups according to 1) dentine treatment (no treatment, DMSO; DMSO+proanthocyanidin, and DMSO+riboflavin-UVA); 2) adhesive strategy (etch-and-rinse and self-etch); and 3) storage time at 2 levels (24 h or 6 years). Untreated sound dentine (SD) served as a positive control. One universal adhesive was used in etch-and-rinse and self-etch mode (iBond Universal; Kulzer). Composite fillings were performed, and specimens were sectioned into resin-dentine bonded beams (0.8 mm2) and tested under tension (0.5 mm/min) until fracture after 24 h or 6 years of water storage, nanoleakage and to determine the crosslinking rate by micro-Raman analysis. Data on bond strength, nanoleakage and relative crosslinking rate were analysed using repeated-measure ANOVA and Tukey test (α = 0.05).

Results: DMSO pretreatments, whether associated with crosslinking agents or not, significantly increased bond strengths and reduced nanoleakage levels of eroded dentin, regardless of the adhesive strategy applied (p < 0.002). After 6 years, eroded dentin pretreated with DMSO, alone or associated with crosslinkers, produced significantly higher bond strength than untreated eroded dentin (p < 0.05).

Conclusion: Dental erosion poses a significant challenge to achieving long-term resin bonding. Such negative effects can be reverted by DMSO pretreatments, without detrimental effects on collagen crosslinking. DMSO may help extend the service life of composite fillings bonded to eroded dentine.