Effect of varying concentrations of home bleaching agents on hardness of a resin composite: An in vitro study

Aim: To evaluate the effect of 10%, 20% and 35% Carbamide Peroxide home bleaching agent on hardness of a microfilled resin composite. Materials and Methods: Forty specimens of micro filled resin composite(Z250, 3M ESPE) were prepared using moulds with dimensions of 4mm diameter x 2mm thickness and cured with a LED polymerization unit (LEDition - Ivoclar Vivadent). The specimens were polished with coarse, medium, fine and super fine polishing discs (Sof-lex, 3M ESPE) and were stored in distilled water at 37?C in an incubator for 24 hours. Specimens were then divided into four groups of 10 specimens each. One group was selected as the control group (not treated with bleaching agents) and was stored in artificial saliva for 7 days at 37?C. The other three groups were treated with 10%, 20% and 35% carbamide peroxide gels respectively (Opalesence PF 10%, Opalesence PF 20% and Opalesence PF 35%, Ultradent) as per the manufacturer’s instructions over a period of 7 days. The specimens were subjected to Shore Durometer for 15 seconds and checked for hardness. The results were analyzed using ANOVA and Post hoc Bonferroni tests. Results: There was no significant difference in the hardness of the specimens belonging to Group A, Group B or Group C when compared with the Control Group. Conclusion: It can be confirmed based on the results of this study that the hardness of the Micro filled Composite resin was not affected by10%, 20 % or 35% carbamide peroxide bleaching gels when used as per the manufacturer’s instructions. Restorations done using microfilled composite resins can be retained after bleaching procedures.