Effect of Dimethyl Sulfoxide (DMSO) on the Micro-tensile Bond Strength of Univeral Adhesives to Dentin

Abstract

Background and Aim Dimethyl sulfoxide is a polar solvent used for the biomodification of bonding substrate and to improve resin-dentin bond strength. This study assessed the effect of DMSO on the microtensile bond strength of universal adhesives to dentin.

Materials and Methods In this in vitro experimental trial, intact human third molars were selected and stored in 0.5% chloramine T until use. After removing occlusal enamel and polishing the cut surfaces by silicone carbide papers, the teeth were randomly assigned into 8 group regarding etching strategy, adhesive type and using DMSO. Universal adhesives of ALL-BOND, Prime & Bond Elect and G-Premio Bond were used in etch & rinse and self etch strategies and with and without applying DMSO. Conventional adhesives of Clearfil SE Bond (self etch) and Adper Single Bond 2 (etch & rinse) were used in the selected teeth to compare the results. Application of 5% DMSO in the etch & rinse strategy was done after dentin etching and moisture control with 50µL volume for 60 seconds using microbrush. In self etch strategy, applying DMSO was done on the dentin covered by smear layer and before primer application. The dentin surface was restored by Valux Plus composite resin and light cured. The specimens were subjected to 500 thermal cycles and after sectioning into pieces by surface sections of 1mm2, their microtensile bond stregnth were obtained by microtensile test device. Failure patterns were assessed by stereomicroscope at 10x magnification. Two-way analysis of variance (ANOVA) test was used to assess the effects of adhesive type and DMSO application on the bond strength. Student t was also used to analyze the effect of DMSO application on the bond strength of the studied adhesives.

Results The effect of DMSO application (p=0.003), adhesive type (p<0.001) and the interaction between DMSO and adhesive type (p=0.027) on the microtensile bond strength of the adhesives to dentin was statistically significant. In self-etch strategy, no significant differences were found regarding the microtensile bond strength of the studied adhesives with and without DMSO application. In etch-rinse strategy, bond strength of ALL-BOND (p=0.02), Prime & Bond Elect (p=0.02) and G-Premio Bond (p=0.001) in the DMSO application were significantly higher than the cases DMSO did not applied. Adhesive type failure patterns were the most failure mode reported in the studied groups.

Conclusion The effects of using or not using DMSO; The type and strategy of adhesive as well as the mutual effects of DMSO application and adhesive type on the microtensile bond strength of adhesives were significant. Application of 5% DMSO significantly increased the microtensile bond strength of universal adhesive to dentin in the etch & rinse strategy. However, no significant effect of 5% DMSO application was seen in the universal adhesives using self etch strategy to improve resin-dentin bond strength.