Objectives: To measure the tooth whitening and the surface and intra-pulpal temperature increase in vitro on extracted upper human incisors after chemical, zoom light and diode laser activated bleaching. Materials and Methods: Thirty caries-free upper human incisors were selected. Teeth were divided into three equal
groups according to the methods of activation of the bleaching agent (n=10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel. Group II was bleached with high intensity advanced power zoom activation light, for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 watt
diode laser for three applications of 30 sec each. Degree of whitening was assessed using an image analysis system,
while temperature rise was recorded using a thermocouple on the external tooth surface and intrapulpal. Results: The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Conclusions: Chemical bleaching produces the same whitening effect as zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than zoom AP light. Diode lasers used to activate bleaching gels are not considered dangerous to the vitality of dental pulps using power settings of 2W.