Methods: Teeth (n=5) were placed into a 37°C thermostatic water container. Shaped (taper .04) root canal were irradiated using Nd:YAP 1.34µm pulsed laser (Lokki, France) at [0.9W/5Hz], [1.4W/5Hz], [1.8W/5Hz], [2W/10Hz], [3W/10Hz] and [4W/10Hz] without water cooling. One to five sequences of laser irradiation were delivered thru a 200µm glass fibre tip at the apical and medial third of the root canal. Temperature changes were recorded at the external surface of the root using a thermal camera (Thermacam B4, Flir, USA).
Results: Temperature maxima did not exceed 41°C after laser irradiation using recommended endodontics values (0.9W/5Hz, 1.4W/5Hz, 1.8W/5Hz). Whatever the power settings the temperature maxima did not exceed 41°C after a single sequence of irradiation. Whatever the power settings, the temperature increase was higher and faster in the apical third. The return of temperature to pre-irradiation values was reached after 60 s maximum.
Conclusions: The observed thermal effects of Nd:YAP root canal laser irradiation exhibit low potential damage to the periradicular tissues and can be considered as a safe procedure for clinical endodontic applications when used in the recommended power/frequency range.