Effects of tooth bleaching on the color and translucency properties of enamel.

PURPOSE: To investigate the changes in color and translucency properties of enamel following 14 days treatment with carbamide peroxide. METHODS: 24 extracted premolars were used in this study. Two enamel-dentin specimens were prepared from each tooth and randomly assigned to be bleached with carbamide peroxide for 14 days or stored in artificial saliva as control. A spectrophotometer (Spectrascan PR650) was employed to measure the color of specimens according to the CIELab system. Color measurement of enamel-dentin specimens was performed prior to and after bleaching. After 14 days bleaching, enamel slabs were prepared by removing dentin parts using a low-speed saw. Then the color and translucency parameter (TP) of enamel slabs was measured over a black and a white background. Data between the experimental group and the control group were analyzed by paired t-test. RESULTS: After bleaching, the color of enamel slabs and controls differed significantly both over the black and white background in L* and b* values (all P < 0.001). The translucency parameter (TP) of bleached enamel slabs was significantly lower than that of controls (P < 0.01). Both the deltaE values of enamel on the two backgrounds were significantly correlated to that of enamel-dentin specimens (P = 0.003; P = 0.012).