Evaluation of Temperature Rise on the External Root Surface During the Application of Laser in Root Canals: an in Vitro Study

Background: Laser systems play an eminent role in endodontic treatment; however, some parameters should be investigated so that damage to the periodontal tissues can be prevented. Hence, in this context, the purpose of this study was to evaluate the temperature rises during the application of different power levels of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and erbium-doped yttrium aluminum garnet (Er:YAG) laser to the external root surface of permanent teeth. Materials and Methods: Sixty mandibular single-rooted premolars were selected and prepared chemomechanically. Nd:YAG laser (Group I) activated irrigation was performed in 30 teeth and remaining 30 received Er:YAG laser (Group II) treatment at three different power levels (1, 1.5, and 2.0 Watt), applied to 10 samples from each group. Type K thermocouple wire, along with a digital calibrated thermometer, was used to measure the temperature changes on the external root surface. Data were assessed with unpaired Student's t-test and two-way ANOVA. Results: With increasing power levels, temperature of external root surface also increased to some extent in both the groups. For apical third, at power level of 1.5 and 2 Watt, the difference in mean temperature between the two groups was found to be significant (6.30°C and 7.75°C; P = 0.005 and 9.11°C and 10.05°C; P = 0.036), whereas for middle third region, it was found that at power level of 2 Watt, the difference in mean temperature between the two groups was significant (6.69°C and 7.91°C; P = 0.007). Conclusion: Both Nd:YAG laser and Er:YAG laser at various power levels lead to rise in temperature on the external root surface, but the temperature changes in all the tested groups remained below the critical threshold.