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

To investigate the changes in color and translucency properties of enamel following 14 days treatment with carbamide peroxide.

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.

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).