“Orthodontic brackets bonded to bleached enamel: a comparative study of the effects of two antioxidants on the shear bond strength”

Abstract

Advancements in dentistry require better management of teeth whitening and orthodontic procedures. Hydrogen peroxide whitening can reduce adhesive strength due to enamel changes and residual oxygen. This investigation in-vitro compared the effects of two antioxidant mediums regarding the strength of the bond between orthodontic brackets applied to teeth bleached 24 hours prior. The goal was to develop guidelines for optimizing bracket bond strength in cases where bleaching precedes orthodontic bonding. It evaluated how in-office teeth whitening with 35% hydrogen peroxide affects orthodontic bracket bond strength and tested the efficacy of antioxidants in reversing this effect. Sixty sound human premolars were separated into four groups: a control group with standard bonding, a bleaching group, and two antioxidant groups treated with 7% sodium bicarbonate or 10% sodium ascorbate following bleaching. Using a universal testing apparatus, the shear bond strength was determined after 24 hours. The study showed that bleaching with 35% hydrogen peroxide significantly reduced orthodontic bracket bond strength (6.60 MPa) compared to the control group (12.98 MPa). However, applying 10% sodium ascorbate or 7% sodium bicarbonate restored bond strength to levels similar to the control group.