Objective To determine the effects of three acidoid bleaching agents on tooth color and dental hard tissues.Methods Bovine tooth blocks with 5 mm×3 mm enamel surface exposure were randomly divided into four groups: white vinegar group (group A),apple vinegar group (group B), 30% hydrogen peroxid group （group C) and deionized water (group D), each containing ninety blocks. In each group, the tooth blocks were further equally divided into three sub-groups,exposing to their respective bleaching agents for 30 s,1 min and 3 min, respectively.The experiment was performed under simulated oral environment.The changes in color,microhardness and morphological characteristics of the tooth blocks were tested by ShadeEye NCC,microhardness tester and SEM. Results Tooth blocks exposed to white vinegar had the most notable decrease in hardness, changes in color and morphological characteristics enamel surface. Conclusion White vinegar,apple vinegar and hydrogen peroxidhave bleaching effects on teeth, but white vinegar may causehigher levels of damage to the hardness and surface configuration of teeth.
