Surface and pulp chamber temperature rises during tooth bleaching using a diode laser: a study in vitro

OBJECTIVE: To measure the surface and pulp chamber temperature increases in vitro on upper and lower anterior teeth during a tooth whitening procedure using a diode laser. METHOD: A thermocouple was used to measure the temperature increase on the surface of an extracted upper central incisor tooth. Pulp chamber temperature readings were made on upper and lower central incisors, lateral incisors and canines. A diode laser recommended for tooth bleaching was tested at three different power settings (1W, 2W, 3W). Temperature measurements were made with and without the bleaching agent present on the labial tooth surface. RESULTS: The increase in surface temperature readings ranged from 37 degrees C (1W) to 86.3 degrees C (3W) with no bleaching gel present. Pulp chamber temperature increases ranged from 4.3 degrees C (1W) to 16 degrees C (3W). The presence of the bleaching gel reduced temperature increases seen at the tooth surface and within the pulp. CONCLUSIONS: The increase in the pulp chamber temperature with the laser used at 1-2W was below the critical temperature increase of 5.5 degrees C thought to produce irreversible pulpal damage. However, a power setting of 3W produced a pulp chamber temperature increase above this threshold (16 degrees C) and caution is advised when using this setting.