Intrapulpal temperature during preparation with the Er:YAG laser: an in vitro study.

OBJECTIVE This investigation evaluated the variation of the intrapulpal temperature when dentine was irradiated by the Er:YAG laser. BACKGROUND DATA The effect of preparation with the Er:YAG laser on the intrapulpal temperature is probably the biggest problem in using the laser for preparation of dental hard tissue. MATERIALS AND METHODS Seventy-two bovine incisors were studied that had the enamel and dentine of the buccal surface polished to a thickness of 2.0 mm. The teeth were divided into three groups, according to the repetition rate used (Group I = 2 Hz, Group II = 4 Hz, and Group III = 6 Hz), and irradiated, with or without water cooling, using 250, 300, and 350 mJ of energy per pulse. Thermocouples were introduced inside the pulp chamber through the palatine opening of the samples and fixed to the vestibular wall of the pulp chamber using a thermal paste. RESULTS It was verified that there was a decrease of the intrapulpal temperature for all of the parameters in the Group I irradiated with water cooling and for the parameters of 350 mJ/4 Hz with water cooling. The other irradiations showed an increase of the intrapulpal temperature, varying from 0.03 degrees to 2.5 degrees C. CONCLUSION We conclude that the use of the Er:YAG laser promoted acceptable temperature increases inside the pulp chamber. However, we do not recommend this procedure without water cooling because macroscopic observations of the dentine irradiated without water cooling showed dark lesions, suggesting carbonization of this tissue.