TEMPERATURE AND SURFACE CHANGES OF DENTIN AND CEMENTUM INDUCED BY CO2-LASER EXPOSURE

The thermal effects of a CO2 laser on the external root surface and in side the root canal were studied in vitro by means of computerized inf rared (IR) thermography and a digital thermometer. One-hundred-and-eig hty tooth roots with single root canals were irradiated internally and externally with laser power set at 0.5, 1, 1.5, 2, 3 and 4 W. The las er was used in two operating modes: pulsed (pulse 0.5 s) and continuou s mode with exposure time of 10 s. Under the conditions of this experi ment, temperature rises of between 1.5 and 19.1-degrees-C at the exter nal root surface and 1.5 and 12-degrees-C inside the root canal and ho rizontally across the sectioned root surface were recorded. The result s obtained with IR camera showed a higher temperature on the external root surface than the digital thermometer during and after lasing the root canal. Scanning electron microscope (SEM) analysis revealed that even low laser energy significantly damaged the external root cementum surfaces.