Shear bond strength analysis of self-etch and total-etch adhesive systems on antioxidant-treated dentin in post-endodontic restoration.

Abstract

Aim: To evaluate the effect of antioxidant pretreatment on the shear bond strength and failure modes of total-etch and self-etch adhesive systems applied to sodium hypochlorite (NaOCl)-treated dentin.

Materials and methods: Eighty extracted human premolars were prepared and irrigated with NaOCl. The specimens were allocated into two groups based on the adhesive strategy employed: total-etch and self-etch. Each group was further subdivided according to antioxidant pretreatment: control (no antioxidant), sodium ascorbate, alpha-tocopherol, and nanocurcumin. Composite resin was bonded, and shear bond strength was tested using a universal testing machine. Failure modes were evaluated microscopically. Data were analyzed using one-way ANOVA with post-hoc tests, two-way ANOVA to assess the effects of antioxidant type and adhesive system, and chi-square analysis for failure modes (P < 0.05).

Results: NaOCl-treated dentin without antioxidant pretreatment showed the lowest bond strength values in both adhesive systems. Sodium ascorbate and nanocurcumin significantly improved bond strength compared with control and alpha-tocopherol, with no significant difference between them. Self-etch adhesives demonstrated lower baseline bond strength but greater recovery following antioxidant pretreatment. Two-way ANOVA revealed significant effects of antioxidant type, adhesive system, and their interaction. Control groups predominantly exhibited adhesive failures, while antioxidant-treated groups showed increased mixed and cohesive failures.

Conclusion: Antioxidant pretreatment effectively restores bonding to NaOCl-treated dentin. Sodium ascorbate and nanocurcumin demonstrated comparable efficacy, with greater benefit observed for self-etch adhesives.