Root surface temperature increase during Er:YAG laser irradiation of root canals.

The authors measured the temperature of the root surface during root canal preparation using Er:YAG laser irradiation and evaluated the thermal effect on the periodontal region. Twenty extracted human teeth with single roots were divided into two groups of 10. These were irradiated using an Er: YAG laser at 2 Hz and 136 to 184 or 170 to 230 mJ/pulse for 1 min with a water spray. The temperature of the root surface was monitored using thermocouples throughout the procedure. The teeth were longitudinally bisected and observed by stereoscopy and scanning electron microscopy. The temperature on the root surface increased by less than 6 degrees C at the apical area and by less than 3 degrees C at the central area. A morphological evaluation revealed no carbonization or melting. These results suggest that the thermal effect on periodontal tissues during root canal preparation using an Er: YAG laser at less than 230 mJ/pulse for 1 min is minimal.