Influence of Antioxidant Agents on the Properties of Bovine Dental Enamel Subjected to Bleaching and Restorative Treatment with Composite Resin

ABSTRACT

Objective:  To evaluate the influence of two antioxidants on the fracture resistance of bleached enamel. It also assessed their impact on color change and surface microhardness.

Material and Methods:  Forty-eight bovine enamel samples underwent three bleaching sessions and were randomly divided into three groups (n=16): Control – No antioxidant application; Sodium Ascorbate – Application of sodium ascorbate for 30 min; DL-alpha-lipoic Acid – Similar to Sodium Ascorbate, but the antioxidant used was DL-alpha-lipoic Acid. Then, color was evaluated with a spectrophotometer, and microhardness was measured using the Knoop test, before the start of the bleaching treatment and immediately after the final application of the bleaching agent and the antioxidant. Afterward, the specimens were restored with composite resin. After seven days, the fracture resistance test was performed using an electromechanical testing machine. Fracture resistance and color evaluation data were subjected to one-way ANOVA, followed by Tukey’s post-hoc test. Microhardness was assessed using Kruskal-Wallis and Dunn tests (p<0.05).

Results:  Sodium ascorbate provided the highest fracture resistance compared to DL-alpha-lipoic acid and the control group after bleaching (p<0.05). The antioxidant agents did not interfere with the whitening effect of 35% hydrogen peroxide (p>0.05).

Conclusion:  Using sodium ascorbate reduced the deleterious effects on enamel microhardness and fracture resistance.

Keywords:
Tooth Bleaching; Antioxidants; Dental Enamel