effects of at-home bleaching gel and two beverages on the microhardness of an aesthetic composite resin

Introduction: the purpose of this study was to investigate the effects of 15% carbamide peroxide, orange juice, and cola on the microhardness of composite resin restoration material. materials and methods: in this in vitro study, forty disk-shaped composite samples were prepared and randomly classified into four groups (n=10); the artificial saliva (control), bleaching agent (15% carbamide peroxide), orange juice, and cola. vickers microhardness was measured on the surface of the samples before and after immersion for 6 and 48 hours. results: the microhardness values of the 15 % carbamide peroxide, orange juice and cola groups were significantly lower after 48 hours compared to the artificial saliva group (p=0.003, p=0.002, p=0.001, respectively). however, these differences were not statistically significant after 6 hours of immersion (p=0.068). when comparing the microhardness values of these groups over time, as expected, these measures significantly decreased, except for the 15 % carbamide peroxide group in which the mean microhardness value did not significantly decrease from baseline after 6 hours immersion (p=0.106). however, there was a significant difference after 48 hours compared to baseline and 6 hours immersion (p=0.001, p=0.004). conclusion: this suggests that 15 % carbamide peroxide gel can be employed as a bleaching agent in cases with composite restorations for a limited amount of time without significant deterioration of the microhardness.