Temperature elevation during root canal treatment with a 445-nm diode laser—an in vitro study

Objective: This study investigated the thermal effects of a 445-nm diode laser on tooth roots of endodontic treatment. Material and methods: A total of 15 human single-rooted extracted teeth were included in the survey. Samples were sectioned at the cementoenamel junction. The root canals were instrumented using a rotary system. Each root was fitted into a resin mold and was fixed in a vertical position using clamps. All samples were placed on a support in a thermal path at 37 °C. The root canals were randomly divided into three groups (n = 5 each): samples were irradiated with 0.6 W continuous wave (CW), 0.4 W CW, and 1.2 W gated mode, at a repetition rate of 10 Hz with a pulse duration of 50 ms. The time-dependent temperature elevations of the cervical, middle, and apical thirds of the roots were recorded at a sampling rate of 2 Hz during laser irradiation with a K-type thermocouple measurement system. Results: The mean temperature rise inside the roots in this study was below 10 °C, whereas the maximum temperature rise of 9.83 °C (0.6 W CW) and 9.81 °C (1.2 W gated mode, repetition rate 10 Hz, and pulse duration 50 ms) was registered in lower incisors, and 4.97 °C was detected at 0.4 W CW. The thermal changes seen in the apical thirds of the root were statically significantly (p < 0.001) and were greater than those at the coronal and middle thirds. Conclusion: The results of this study suggest that 445-nm diode lasers may provide a safe temperature for endodontic applications. © 2018, Springer International Publishing AG, part of Springer Nature.