Effect of simulated pulpal microcirculation on intrachamber temperature changes following application of various curing units on tooth surface.

OBJECTIVE: The purpose of this study was to evaluate ex vivo the rise in intrachamber temperature induced by the application of various curing units on tooth surface, under conditions of continuous water flow inside the pulp chamber simulating pulp microcirculation.
METHODS: Fifteen extracted intact human teeth were selected. Intrachamber temperature increases were induced by applying the following curing units to the buccal aspect of the tested teeth: a conventional halogen lamp, two high-intensity halogen lamps, a plasma arc curing light, a mercury/metal-halide lamp, and a diode laser. Temperature changes on the tooth surfaces were recorded using thermocouples connected to a data logger. The Greenhouse-Geisser and Bonferroni tests in the SPSS software package were used for analysis of the data. The level of significance was set at 0.05.
RESULTS: Under conditions of water flow the average intrachamber temperature rise was less than 6 degrees C, for all curing units. Without water flow, the increase in pulp temperature exceeded 6 degrees C for all units except the conventional halogen lamp. The diode laser produced a significantly greater temperature increase than any other curing unit. Application of the diode laser and the two high-intensity halogen lamps to lateral incisor specimens produced significantly greater temperature increases than other teeth.
CONCLUSIONS: When the simulated pulp microcirculation was absent, the temperature increases produced by all curing units except the conventional halogen lamp were large enough to be potentially harmful to the pulp. On the contrary, with the cooling effect of water flow inside the pulp chamber, all units proved to be safe for use.