A Thermal Investigation During Dental Bleaching in Vitro Study

Objective: Investigate the surface temperature variation of cervical region (infrared thermography) as well as the temperature within pulpal chamber (thermocouples) of human mandibular incisors when submitted to dental bleaching using two different 35% hydrogen peroxide gels, red (HP) and green (HPM) activated by Halogen light (HL) and LED. Background data: temperatures above 5.5¢ªC can be considered potentially threatening to pulp vitality while higher than 10¢ªC can result in periodontal injury. Methods: The samples were randomly divided into 4 groups (n=10), according to the bleaching agent and catalyst light source. Results: Mean values and standard deviations of the temperature increase inside the pulpal chamber in the HL groups was 4.4 +/- 2.1° using HP, and 4.5 +/- 1.2° using HPM; whereas in the groups using LED, it was 1.4 +/- 0.3° for HP, and 1.5 +/- 0.2° using HPM. For the root surface, the maximum temperature variations in the groups irradiated with HL were 6.5 +/- 1.5° for HP, and 7.5 +/- 1.1° using HPM; whereas in the groups irradiated with LED, it was 2.8 +/- 0.7° using HP, and 3 +/- 0.8° for HPM. There were no statistically significant differences in pulpal and surface temperature increases between the groups using different gels although the mean temperature increase values were significantly higher for the groups irradiated with HL when compared with those irradiated with LED (Tukey test, p < 0.05). Conclusion: LED could be safe for periodontal and pulpal tissue when using this method, but HL should be used with care.