In vitro analysis of human tooth pulp chamber temperature after low-intensity laser therapy at different power outputs

Abstract

In vitro studies have provided conflicting evidence of temperature changes in the tooth pulp chamber after low-level laser irradiation of the tooth surface. The present study was an in vitro evaluation of temperature increases in the human tooth pulp chamber after diode laser irradiation (GaAlAs, λ = 808nm) using different power densities. Twelve human teeth (three incisors, three canines, three premolars and three molars) were sectioned in the cervical third of the root and enlarged for the introduction of a thermocouple into the pulp chamber. The teeth were irradiated with 417mW, 207mW and 78mW power outputs for 30s on the vestibular surface approximately 2mm from the cervical line of the crown. The highest average increase in temperature (5.6°C) was observed in incisors irradiated with 417mW. None of the teeth (incisors, canines, premolars or molars) irradiated with 207mW showed temperature increases higher than 5.5°C that could potentially be harmful to pulp tissue. Teeth irradiated with 78mW showed lower temperature increases. The study showed that diode laser irradiation with a wavelength of 808nm at 417mW power output increased the pulp chamber temperature of certain groups of teeth, especially incisors and premolars, to critical threshold values for the dental pulp (5.5°C). Thus, this study serves as a warning to clinicians that "more" is not necessarily "better".