Does the application of dimethyl sulfoxide improve resin bonding to eroded dentine? Four-year in vitro evaluation

Objective: To evaluate the effect of dimethyl sulfoxide (DMSO) on the microtensile bond strength (mu TBS) and nanoleakage (NL) of universal adhesives on eroded dentine, immediately and after four years of water storage.Methods: Sixty-four sound human molars were distributed into 16 groups according to (1) Dentine surface (sound and eroded dentine); (2) dimethyl sulfoxide application (with or without); (3) Application mode (etch-and-rinse or self-etch) and (4) Storage time (immediate and four years). One mild universal adhesive was used (Scotchbond Universal). The restoration was then performed with a composite resin and the specimens were sectioned into resin-dentine bonded sticks. Resin-dentine bonded sticks were tested (immediately and after four years of water storage) for mu TBS (0.5 mm/min) or used to assess NL. Data on mu TBS and NL were analyzed using four-way ANOVA and Tukey's test (alpha = 0.05).Results: Only the 3-way cross-product interaction 'substrate vs DMSO vs time' was statistically significant (p = 0.007). Eroded dentine showed a lower mean of mu TBS and a higher mean of NL values than sound dentine. However, when DMSO was applied, no significant decrease of mu TBS or NL values was observed after four years of water storage, regardless of adhesive strategies, or dentine evaluated, when compared to immediate results.Significance: Water-based DMSO pre-treatments not only prevent degradation of MDP-containing simplified adhesives but also serve as a potential alternative to improve long-term bonding properties to eroded dentine. The versatility of using a single pre-treatment for both self-etch or etch-and-rinse bonding to eroded dentin may facilitate future clinical applications.

Automated summary

This study evaluated the effect of DMSO on the bonding strength and nanoleakage of universal adhesives on eroded dentine. The results showed that there was no significant decrease in mu TBS and NL values after four years of water storage when DMSO was applied.