Temperature changes accompanying near infrared diode laser endodontic treatment of wet canals.

INTRODUCTION: Diode laser endodontic treatments such as disinfection or the generation of cavitations should not cause deleterious thermal changes in radicular dentin. METHODS: This study assessed thermal changes in the root canal and on the root surface when using 940 and 980 nm lasers at settings of 4 W/10 Hz and 2.5 W/25 Hz, respectively, delivered into 2000-mum fibers to generate cavitations in water. The root surface temperature in the apical third was recorded, as was the water temperature in coronal, middle, and apical third regions, by using thermocouples placed inside the canal. Lasing was undertaken with either rest periods or rinsing between 5-second laser exposures. RESULTS: Both diode lasers induced only modest temperature changes on the external root surface at the settings used. Even though the temperature of the water within the canal increased during lasing by as much as 30 degrees C, the external root surface temperature increased by only a maximum of 4 degrees C. Irrigation between laser exposures was highly effective in minimizing thermal changes within the root canal and on the root surface. CONCLUSIONS: Diode laser parameters that induce cavitation do not result in adverse thermal changes in radicular dentin.

Cavitational effects in aqueous endodontic irrigants generated by near-infrared lasers.

INTRODUCTION: Laser-generated pressure waves may have application for removing debris and smear layers from root canals. Past work has employed middle infrared erbium lasers. The present study examined whether near infrared 940 and 980 nm diode lasers (Biolase Ezlase and Sirona Sirolaser, respectively) could induce cavitations in aqueous media. METHODS: Laser energy was delivered into a capillary tube using a 200 microm fiber, and the formation of cavitations observed with a microscope. In the first part of the study, a range of laser parameters were trialled to establish conditions which form cavitations within 5 seconds of the commencement of laser irradiation. The second part of the study compared cavitation in distilled water, aerated tap water, degassed distilled water, ozonated water, 3 and 6% hydrogen peroxide using panel setting of 2.5 W/25 Hz for the Sirolaser, and 4 W/10 Hz for the Ezlase. RESULTS: Both diode laser systems could induce cavitation in water-base media by the formation and implosion of water vapour. Laser power played a more important role than pulse frequency or pulse interval. Optimal laser-initiated cavitation occurred when weak (3%) peroxide solutions were used as the target irrigant, rather than water. CONCLUSION: This phenomenon has potential for enhancing debridement in endodontics.