Root Surface Temperature Changes During Root Canal Laser Irradiation with Dual Wavelength Laser (940 and 2780 nm): A Preliminary Study.

OBJECTIVE: This study aimed to evaluate the temperature changes on the root surface during root canal irradiation using 2780 nm erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) and 940 nm diode lasers in an alternating sequence.

MATERIALS AND METHODS: Eighteen single-rooted human teeth were randomly divided into three groups (n = 6). Teeth were embedded in a resin block, and six thermocouples were introduced at different positions on the tooth surfaces, while immersed in a 37°C thermal bath during laser irradiation. The laser radial firing tip (RFT)2 was operated in helicoidal movements and withdrawn from the root canal in a coronal direction at a speed of 2 mm/sec. Group A was irradiated with the Er,Cr:YSGG laser (1.25 W, 25 mJ, 50 Hz, 50 μs pulse duration, 50% water, and 30% air spray); Group B was irradiated with the Er,Cr:YSGG laser (same settings) and a 940 nm diode (2 W, with 20% duty cycle), and Group C was irradiated with the Er,Cr:YSGG laser (same settings) and a 940 nm diode (2 W, 50% duty cycle).

RESULTS: The maximum temperature recorded was in the apical thirds of Groups A-C, resulting in increments of 8.35°C, 7.33°C, and 3.82°C, respectively. All measured temperatures were considerably below the critical value of 10°C.

CONCLUSIONS: The alternate use of Er,Cr:YSGG and 940 nm diode lasers can be considered biologically safe to be used in endodontics.