Effect of mouthguard bleaching on enamel surface.

PURPOSE: To evaluate in vitro the effect of 10% carbamide peroxide in a mouthguard on the shear bond strength of resin composite to bleached enamel surfaces and morphological changes in these surfaces. MATERIALS AND METHODS: Thirty anterior extracted were divided into a control and a test group. Plastic trays were made for each tooth and the test group treated with Opalescence bleaching gel and incubated at 37 degrees C humid environment for 8 hours. The bleaching agent was washed and the trays replaced with water-soaked cotton wool for another 16 hours in the incubator. This procedure was repeated every day for 21 days. The control group was just treated with the water-soaked cotton wool. Selected teeth from both groups were evaluated with the SEM and 72 hours after the bleaching treatment, Scotchbond 2/Silux Plus rings were bonded to the enamel surfaces in both groups and sher bond strength testing performed. RESULTS: Bleaching created some enamel porosity and significant reduction in the resin composite shear bond strength.