Abstract
The risk of thermal injury to pulpal tissue is recognized as a major limitation to the use of lasers for dental hard tissue procedures. This study examined thermal changes at the level of the dental pulp in human molar teeth irradiated in vitro with a CO2 dental laser using pulsed and continuous modes of operation. The laser parameters were those used clinically for procedures such as laser etching of enamel and treatment of external resorption. For a given energy, pulsed modes with low duty cycles induced markedly less thermal change than continuous wave. With regard to thermal properties of tooth structure, time required to reach the maximum temperature reduced, and time required to cool to baseline increased with increasing laser exposures. These findings suggest the importance of pulsed modes of operation in reduction of risk of injury to the dental pulp.