Effect of Dentin Pretreatment With Dimethyl Sulfoxide Solution on Interfacial Fracture Toughness of Composite Resin to Wet and Dry Dentin.

OBJECTIVES

This study aimed to investigate the effect of dentin pretreatment with dimethyl sulfoxide (DMSO) on the interfacial fracture toughness (IFT) of composite resin bonded to dentin under varying collagen hydration conditions, addressing conflicting findings in existing literature.

METHODS AND MATERIALS: A total of 84 dentin samples were randomly assigned to six groups based on the following variables: initial collagen hydration condition (wet or dry), dentin pretreatment (DMSO/ethanol or control), and collagen moisture condition prior to hybridization as follows: (1) Wet dentin control (no pretreatment, blot-dried), (2) Wet dentin + DMSO/EtOH pretreatment (blot-dried), (3) Wet dentin + DMSO/EtOH pretreatment (air-dried), (4) Dry dentin control (no pretreatment, air-dried), (5) Dry dentin + DMSO/EtOH pretreatment (blot-dried), and (6) Dry dentin + DMSO/EtOH pretreatment (air-dried). A two-step etch-and-rinse (E&R) bonding technique was utilized. After bonding, samples were stored in distilled water for 24 h and subjected to 3000 thermocycling cycles. IFT was measured, and fracture patterns were analyzed using stereomicroscopy and scanning electron microscopy (SEM). Statistical analysis employed ANOVA at a significance level of 0.05.

RESULTS

The average IFT revealed significant differences between initial dentin conditions (p  < 0.001), with higher values in the wet condition compared to dry. Both initial dentin condition (p  < 0.001) and DMSO pretreatment (p = 0.010) significantly influenced IFT, while their interaction effect was not significant (p = 0.937). Notably, the Dry (Control) group exhibited lower IFT compared to the Dry-DMSO/EtOH-Blot group, which showed higher average IFT (p = 0.032). Adhesive failure was the predominant mode across all groups, with no significant differences in fracture patterns.

CONCLUSIONS

The DMSO/EtOH solution, used as a dentin pretreatment, positively affected the IFT of composite resin, particularly for wet dentin surfaces.