Evaluation of Temperature Changes Promoted in Dental Enamel, Dentin and Pulp During the Tooth Whitening with Different Light Sources

Considering the great demand for aesthetic treatments in the dental hard tissues, the wide availability of whitening gels and light sources, as well as the concern with the harmful effects that the increase in temperature can bring to biological tissues, this study verified the changes in temperature of dental enamel, root dentin and pulp chamber during the in-office tooth whitening procedure with different light sources and whitening gels. Sixty recently-extracted lower human incisor teeth were prepared and randomly distributed among six experimental groups for treatments: G₁-red whitening gel without light; G₂-green gel without light; G₃-red gel and exposed to blue LED light; G₄-red gel and exposed to green LED light; G₅-green gel and exposed to blue LED lighting; G₆-green gel and exposed to red laser light. During the treatments, as well as one minute after finishing them, the pulp and surface temperature variations of the enamel and root dentin were monitored using four thermocouples. The pulp temperature changes were 0.3 °C (G₁), 0.8 °C (G₂), 1.8 ± 0.5 °C (G₃), 1.9 ± 0.5 °C (G₄), 3.35 ± 0.6 °C (G₅), 0.34 ± 0.1 °C (G₆). The temperature differences at the interface between gel and enamel were 0.3 °C (G₁), 0.9 °C (G₂), 4.42 ± 0.9 °C (G₃), 4.9 ± 1.1 °C (G₄), 4.7 ± 1.1 °C (G₅) and 1.5 ± 0.2 °C (G₆). The root surface temperature differences were 0.3 °C (G₁), 0.6 °C (G₂), 3.05 ± 0.87 °C (G₃), 2.6 ± 0.96 °C (G₄), 3.8 ± 0.27 °C (G₅) and 0.30 ± 0.1 °C (G₆) and the temperature differences on the enamel side were 0.25 °C (G₁), 0.46 °C (G₂), 3.2 ± 0.7 °C (G₃), 2.97 ± 0.6 °C (G₄), 5.13 ± 1.2 °C (G₅) and 0.70 ± 0.25 °C (G₆). None of the configurations of the experimental groups causes permanent damage to the dental tissues, however the combination of green gel + blue LED should be avoided, since it is the one that promotes greater temperature increases in these tissues.