Influence of dimethyl sulfoxide on microtensile bond strength and surface morphology of tribochemically repaired nanohybrid composite: An in vitro study.

BACKGROUND: The emphasis on minimally invasive dentistry has increased the use of resin composites, but these restorations remain prone to secondary caries, fracture, and interface degradation, often requiring repair or replacement. Repairing rather than replacing can preserve tooth structure and shorten treatment. This study assessed how 50% dimethyl sulfoxide (DMSO) affected the surface topography and microtensile bond strength (µTBS) of a nanohybrid composite that had undergone tribochemical repair. MATERIALS AND METHODS: Aged nanohybrid composite blocks were assigned to three groups: Group C (control), Group CS (CoJet sandblasting), and Group CD (CoJet sandblasting +50% DMSO). All specimens received silane and universal adhesive, followed by repair with fresh nanohybrid composite. After thermocycling, µTBS was measured using the microtensile test. The surface morphology of additional specimens was assessed using scanning electron microscopy (SEM). Tukey's post hoc test (α = 0.05) and one-way analysis of variance were used to examine the data. RESULTS: µTBS differed significantly among the three groups (P < 0.05). Mean µTBS values were 69.92 ± 9.45 MPa (Group C), 106.97 ± 9.55 MPa (Group CS), and 123.86 ± 8.64 MPa (Group CD), with Group CD showing the highest bond strength. SEM revealed a relatively smooth surface in the control group, distinct microretentive features after CoJet treatment, and a more irregular, cleaner surface when DMSO was applied after tribochemical conditioning. CONCLUSION: Within the parameters of this in vitro investigation, the use of 50% DMSO following tribochemical surface treatment considerably enhanced the bond strength and surface properties of the repaired nanohybrid composite, thereby supporting its usage as a simple additional step in composite repair procedures.