Effect of heating antioxidants and delayed bonding on bond strength to bleached enamel

Abstract

Objective: The aim of this study was to evaluate the influence of heating natural antioxidants on their antioxidant activity and on micro shear bond strength of composite resin to bleached enamel. Materials and methods. A hundred-eighty flowable composite cylindrical specimens of 0.8 mm diameter and 1 mm length were bonded to enamel substrate for microshear bond strength evaluation. Six study groups were created (n=30). Group 1: No bleaching, Group 2: Bleaching only, Group 3: Bleaching+ Pine Bark Extract at Room temperature, Group 4: Bleaching + Pine Bark Extract preheated to 60° C. Group 5: Bleaching+ Grape Seed Extract at Room temperature, Group 6: Bleaching+ Grape Seed Extract preheated to 60° C. All groups were tested immediately (subgroup a), after one week (subgroup b) and two weeks (subgroup c). Both extracts were tested for their antioxidant activity using DPPH assay at room temperature, 40° and 60°. Two- and one- way ANOVA were used to explore the effect of different surface treatments and bonding time on microshear bond strength. Results. DPPH results showed the heated antioxidant extracts to have significantly higher antioxidant activity than their non-heated counterparts.