Efficacy of anti-oxidants when used for distinctive time to re-establish bond strength

Introduction: The objective was to evaluate the effect of three antioxidants Sodium thiosulphate, Sodium ascorbate and Rosemarinic acid with different application times in reversing the bond strength of dentine compromised by sodium hypochlorite (NaOCl) and EDTA. Material and Method: Crowns of bovine incisors were cut to expose the dentine pulp chamber from which 84 (buccal and lingual surface) samples were selected. The specimens were polished and randomly distributed into 6 groups. Each group has n=7 i.e 6 X 7= 42 samples. Group 1:0.9% sodium chloride for 30mins (negative control), Group 2: 5.25% NaOCl for 30mins, 17% EDTA for 3mins and 5.25% NaOCl for 1min (positive control). Groups (3, 4, 5 and 6) were treated in the same manner as positive control. Group 3 samples were neutralized by immersion in an inert solution (saline) for 10mins.The samples of Groups 4, 5, 6 were neutralized with the antioxidant reagents mentioned above. Group 4, 5, 6 were sub-grouped for 3mins, 5mins and 10mins i.e 4a, 4b, 4c 5a, 5b, 5c and 6a, 6b, 6c. The specimens were dried and etched with total adhesive system according to manufactures instructions. Followed by 3 mm build-up of composite resin incrementally to bonded dentine and light cured for 20 seconds. The micro tensile bond strength was determined using universal testing machine and was statistically analysed with independent sample t-Test with 95% confidence limits. Results: At 3 mins and 5mins rosemary extract performed better than sodium thiosulphate and sodium ascorbate (with P values: 0.000,0.000 and 0.000,0.040). Rosemary extract when used for 3mins and 5 mins showed a significantly better performance than at 10mins (with P values 0.000 and 0.001). At 3 mins and 5mins rosemary did not show any significant difference.