Whitening gel and light source influence on pulp chamber temperature

ABSTRACT

Introduction: The chemical injury caused to the pulp by the penetration of the whitening gel is already known, but another possible cause may be the heat generated by the irradiation of the whitening gel with light sources to accelerate the whitening reaction. Objective: To evaluate in vitro the temperature increasing in the pulp chamber during in-office bleaching with different gel concentrations and light sources. Material and methods: A maxillary human central incisor was used in the 6 groups evaluated. The specimen was sectioned 3 mm apical to the cementoenamel junction. The root canal and pulp chamber were cleaned and widened with a diamond bur to receive the sensor of a thermocouple thermometer. The following hydrogen peroxide gel concentrations were evaluated: 35%, 25%, 15%, and 10%; and the following light sources were applied: blue hybrid LED/laser and violet hybrid LED/laser. The specimen bleaching was repeated 6 times per group. As a control, the temperature was measured with the application of light, without applying any gel. Results were evaluated with one-way ANOVA and Tukey's test (α = 5%). Results: Significant differences between groups were observed (p < 0.05). The blue LED without the gel induced the smallest heat (37.5 ± 0.2) and the blue LED with 15% gel caused the highest heat (38.2 ± 0.3). The combination of violet LED with the 10% gel caused no significant increase in temperature compared to the control in which light was used without gel (p> 0.05). Conclusion: No increase in pulp chamber temperature was higher than 2°C.