Surface and intrapulpal temperature changes in teeth using different violet LED devices under continuous or pulsed irradiation protocols: an in vitro study

Purpose To evaluate intrapulpal and tooth surface temperature increases (ΔT) produced by different violet LED devices (405 nm) under continuous and pulsed irradiation protocols in an in vitro model. Methods Three human mandibular incisors were prepared and instrumented. A 35% hydrogen peroxide gel was applied to the enamel surface and replaced at each measurement. Three violet LED devices with different configurations were tested: Device #1 (300 mW/LED), Device #2 (375 mW/LED), and Device #3 (250 mW/LED). A 2 cm distance from the enamel surface was maintained, and two irradiation protocols were applied: continuous irradiation for 30 min and a pulsed protocol (1-minute irradiation followed by a 30-second pause, totaling 30 min). Temperature was recorded in real time, and temperature increase (ΔT, °C) relative to baseline was used for the analyses. Data were analyzed using peak temperature increase (ΔT) at each 5-minute interval over the 30-minute experimental period, employing two-way repeated-measures ANOVA (α = 5%). Results No measured intrapulpal temperature increase exceeded the historical 5.5 °C reference value. Device #2 frequently showed numerically higher temperature increases; however, pairwise differences between individual devices were not statistically significant after correction for multiple comparisons. Conclusion Within the limitations of this in vitro study, numerical differences in thermal behavior were observed among the tested violet LED devices. Under the tested experimental conditions, no measured intrapulpal temperature increase exceeded the historical 5.5 °C reference value. These findings describe the thermal behavior observed in the present in vitro model and should not be interpreted as evidence of clinical safety.