MEANDROS MEDICAL AND DENTAL JOURNAL, sa.3, ss.204-214, 2020 (ESCI)
Objective: This study aimed to evaluate the effect of four experimental antioxidant protocols on the shear bond strength of a resin-based composite to bleach the enamel and dentin. Materials and Methods: Using extracted bovine incisors, 140 enamel/140 dentin specimens were prepared. Both enamel and dentin samples were assigned into seven groups, individually (n=20): ENC/DNC= negative control, EPC/DPC= positive control, EDR/DDR= delayed restoration, ESA/DSA= sodium ascorbate, EGT/DGT= green tea, ER/DR= rosemary and EGTR/DGTR= green tea and rosemary combination. Experimental antioxidant solutions prepared from sodium ascorbate, green tea, or rosemary extracts were applied to the bleached enamel/dentin samples in the ESA/DSA, EGT/DGT and ER/DR groups, respectively. The mixture of the green tea/ rosemary extract solutions at a 1:1 ratio was applied to the EGTR/DGTR groups to investigate possible synergistic antioxidant interaction. The shear bond strength (SBS) test was conducted at a crosshead speed of 0.5 mm/minute. Failure modes were assessed under a stereomicroscope at x40 magnification. Data were analysed statistically using Welch-ANOVA and Tamhane post-hoc tests. Results: The lowest and highest mean SBS values were obtained in the positive control groups (EPC/DPC) and negative control groups (ENC/DNC), respectively (p<0.05). Delaying of the composite resin restorations for 15 days improved bonding to the bleached enamel/dentin compared to the positive control groups (p<0.05). All the antioxidant protocols, except green tea and rosemary combination, exhibited a bonding strength that was statistically similar to that of the relevant delayed restoration groups (p>0.05). Synergistic antioxidant interaction could not be obtained in the green tea and rosemary combination protocol. Conclusion: Natural plant-derived antioxidants can be an alternative to synthetic sodium ascorbate and may enable immediate resin restorations of bleached tooth structures.