LED polywave light irradiance affects the temperature of the pulp and buccal surface during bleaching

This is the authors' abstract. We don't add key points for this paper.

Objective: The intrapulpal and buccal surface temperatures were evaluated during in-office bleaching with 40% carbamide hydrogen peroxide using different irradiant values of polywave LED light. Methods: Forty bovine incisors received in-office bleaching for 40 minutes (Opalescence Boost) with application of different irradiant values of polywave light (Valo Corded): control (absence of light), Standard (1000 mW/cm2), High (1400 mW/cm2) and Xtra (3200 mW/cm2). The light was applied in fractions of 8 cycles (15 seconds of light and 5 minutes without light). A type k thermocouple was used to evaluate intrapulpal and buccal surface temperatures at the end of each light activation cycle throughout the clinical session. Results: There was significant variation in pulp chamber temperature (p<0.0001) throughout the treatment in all groups. Xtra showed a significantly higher temperature than the control at all time intervals as from the 2nd activation onwards (p<0.05). On the buccal surface, the control was the only group that did not show a significant change in temperature (p>0.05) over time. Conclusion: The irradiant exposure value of the Xtra polywave LED light can lead to greater increase in intrapulpal and buccal surface temperatures when compared with other types of irradiance. Although the temperature values did not exceed the limits considered capable of damaging the pulp, the use of light for dental bleaching reinforces the contraindication, as the results do not support this claim.