Objective: The objective of this study was to evaluate, in vitro, the influence of two concentrations of carbamide peroxide bleaching agents with and without topical desensitizing gels on enamel microhardness, roughness, and shear bond strength to orthodontic metal brackets.
Methods: One hundred and sixty-eight (168) human extracted premolars for orthodontic purpose were obtained and randomly divided into seven groups (n =24): Group 1, control group (Neither bleaching nor desensitizing); Group 2, bleached with 22% carbamide peroxide; Group 3, bleached with 22% carbamide peroxide followed by Minerals desensitizing gel; Group 4, bleached with 22% carbamide peroxide followed by ‘'D.M. Sense'' desensitizing gel; Group 5, bleached with 35% carbamide peroxide; Group 6, bleached with 35% carbamide peroxide followed by Minerals desensitizing gel; Group 7, bleached with 35% carbamide peroxide followed by ‘'D.M. Sense'' desensitizing gel. Microhardness test and roughness measurements were carried on specimens immediately after finishing of treatment, using Vickers Diamond Microhardness Tester and Roughness Analyzer respectively. Only specimens for brackets shear bond strength (SBS) were stored for 7 days in distilled water after treatments and before testing. Shear bond strength were tested using Instron Universal Testing Machine
Results: Statistical significant differences were found between groups. Groups that received bleaching treatments only, showed greater deterioration in all tested properties than, groups received desensitizing treatments after bleaching treatment.
Conclusion: Application of desensitizing agent after in-home bleaching is highly recommended to minimize deleterious effects of bleaching agents.