External root thermal analysis of three different obturation techniques.

Background: The purpose of this study was to assess the external root surface thermal behavior when submitted to three different obturation techniques. Material and Methods: Forty-five single-rooted premolars were selected, prepared and randomly divided into three groups according to the studied obturation techniques: lateral condensation (LC), single cone technique (SCT) and injectable thermoplasticized technique (IT). Each tooth was placed in a customized apparatus and connected to a thermocouple. A FLIR T650sc infrared thermal camera was used to assess root temperature in a room under controlled temperature and humidity. Temperature values were recorded using the thermal camera and thermocouples before, during and 30, 60, 90, 120, 150s after obturation. Shapiro-Wilk, QQ-plot, Levene's, ANOVA-three-way, Mauchly's sphericity, Box's M and Bonferroni tests were used to assess data. The significance level was set at 5%. Results: Infrared assessment showed significant temperature changes between time intervals, obturation techniques and root thirds. Temperature increase was observed 30s after obturation for STL, LC and IT, followed by a gradual temperature decline, with temperature values similar to the initial temperature at 150s for LC and IT. SCT temperature values only returned to normal 60s after obturation in the apical third and 90s in the middle and cervical thirds. In all techniques, the temperature did not rise above the critical limit of 10°C. Conclusions: All studied obturation techniques increased root surface temperature with IT showing the highest temperature increase. However, the temperature increase does not exceed the acceptable limits, not causing damage to the surrounding tissues.