Temperature and surface changes of dentine and cementum induced by CO2 laser exposure.

The thermal effects of a CO2 laser on the external root surface and inside the root canal were studied in vitro by means of computerized infrared (IR) thermography and a digital thermometer. One-hundred-and-eighty 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 laser was used in two operating modes: pulsed (pulse 0.5 s) and continuous mode with exposure time of 10 s. Under the conditions of this experiment, temperature rises of between 1.5 and 19.1 degrees C at the external root surface and 1.5 and 12 degrees C inside the root canal and horizontally across the sectioned root surface were recorded. The results 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.