Temperature variation in pulp chamber during dental bleaching in presence or absence of light activation

PURPOSE: In addition to the chemical damage due to bleaching gels penetration into the pulp during pulp vitality dental bleaching, another possible aggressive factor could be the heat generated by the exothermal oxidation reaction of the bleaching gel, which may also be aggravated by the use of light activation. This study assessed the temperature variation in the pulp chamber in human teeth, using three different bleaching gels with or without LED light activation. METHODS: Thirty human pre-molars were cut longitudinally to obtain buccal and lingual halves. The 60 specimens were divided into 3 groups, and the bleaching gel used varied as follows: 35% hydrogen peroxide (WHP); 37% carbamide peroxide (W) and 38% hydrogen peroxide (OX). Half of the specimens were submitted to bleaching with light activation and, the other half, without light activation. The light source used was the light emitting diode appliance (LED, 3-Light, Clean Line), and the intrapulpal temperatures were measured by using a digital thermometer. Data were analyzed by ANOVA and Tukey's tests (alpha=5%). RESULTS: The intrapulpal temperatures (inºC) were as follows: without light activation (WHP= 0.68b; W= 0.40b; OX= 0.48b); with light activation (WHP= 2.35a; W= 1.60a; OX= 1.80a ). CONCLUSION: LED light activation of bleaching gels increased the temperature in the pulp chamber, but did not achieve the critical temperature value of 5.5ºC.