Comparative evaluation of two antioxidants on reversing the immediate bond strength of bleached enamel: In vitro study

Abstract

Background: Tooth bleaching causes a significant decrease in the bonding strength between the resin and human enamel. Nevertheless, the effects of different antioxidant types on the immediate bonding strength of resin and bleached enamel were significantly different. Therefore, the objective of this study was to compare the effects of 2 antioxidants for enhancing the bond strength of the resin to bleached enamel. Material/Methods: There were 48 enamel blocks performed from 48 recently extracted maxillary central incisors. There were 8 groups: NC (negative control, no bleached specimens restored without antioxidants); NA (no antioxidant, bleached specimens bonded immediately without any antioxidants); SA30, SA60, and SA120 (bleached specimens accepted the management of 10% sodium ascorbate (SA) for 30 minutes, 60 minutes, and 120 minutes, respectively, before restored); PC30, PC60, and PC120 (bleached specimens received treatment of 5% proanthocyanidins (PC) for 30 minutes, 60 minutes, and 120 minutes, respectively, before restored). We measured the micro-tensile bond strength of specimens and used 2-way ANOVA to analyze the data. Results: The mean±standard deviation bond strength measured were: NC, 29.99±4.00; NA, 14.90±1.97; SA30, 18.60±2.20; SA60, 22.57±2.71; SA120, 26.15±3.85; PC30, 16.78±2.29; PC60, 19.13±2.24, PC120, 23.90±2.01 MPa. In addition, the fracture types were mainly of an adhesive mode (88.75%), followed by mixed (7.5%), and cohesive (3.75%). Conclusions: 10% sodium ascorbate provided a comparatively more promising improvement for immediate bond strength than 5% proanthocyanidins when the same duration of antioxidant was applied.