Análise termográfica e volumétrica de dentes submetidos a diferentes técnicas de obturação endodôntica e remoção de Guta-Percha

Abstract

Introduction: Endodontic obturation techniques are constantly improving to promote the three-dimensional hermetic sealing of the root canal. Removing gutta-percha for retreatment or prosthetic rehabilitation is a routine practice in the dental clinic. Both endodontic filling and gutta-percha removal require the use of heated instruments or heat generators, which can damage the periodontal tissues at a temperature above 10 ° C. Objective: To evaluate the root surface temperature and the volume of the filling material using different endodontic filling techniques; and evaluate the root surface temperature during gutta-percha removal using different methods of gutta-percha removal. Methodology: This study was divided into two axes corresponding to the two articles derived from this research. The total sample of the research consisted of 135 single-rooted premolars. Axis I: 90 teeth were used in this axis, 45 for thermal analysis and 45 for volumetric analysis. For each group, three filling techniques were assessed: single cone, lateral condensation and thermomechanical, at different times according to the analysis performed. For thermal analysis, the FLIR Infrared thermal camera model T650sc was used. The thermography laboratory was maintained under controlled conditions of temperature and humidity. The thermal camera was positioned 30cm from the teeth, arranged on a support built for this purpose. Thermal images were acquired at 15-second intervals, starting before the endodontic filling procedure until temperature normalization. Volumetric analysis was performed on the remaining 45 filled teeth in a controlled laboratory environment, and scanned 5 days after obturation, using the NIKON microtomograph, model XTEK XT-H 225 ST with parameters that allowed a resolution of 11 µm. The microtomographic analysis of the volumes was performed by double segmentation of volumes using imageJ® software. The thermal images were analyzed by thirds with the aid of the straight tool from the FLIR Tools v software. 6.4. at different study. Axis 2: 45 teeth were equally divided according to the gutta-percha removal instruments assessed: Largo Peeso, Protaper retreatment and Reciproc. The temperature variation was analyzed simultaneously by infrared thermography (axis 1 methodology); and by three K thermocouples connected to a digital thermometer (RDXL4SD, Omega) adhered to the cervical, middle, and apical thirds of the teeth under study. The temperatures recorded with the thermocouple followed were done in the same study times as the infrared thermography. Statistical analysis was performed in a descriptive and inferential way using the statistical package SigmaPlot 12. Mann Whitney, Kruskal-Wallis and Friedman non-parametric tests were chosen, respecting the nature of dependence and number of groups of the samples, non-parametric tests were used Mann-Whitney, Kruskal-Wallis and Friedman chosen respecting the nature of dependence and number of groups of the samples, with two-way Tukey analyzes. Results: Axis 1: the highest median temperature was 7.5 ° C (Q25 5.2 - Q75 13.3), observed in the thermomechanical technique 15 seconds after endodontic filling, only after 60 seconds did the temperature decline significantly in all groups. The cervical third had the highest temperatures (Md 18.6 - Q25 15.4 / Q75 26.2). The thermomechanical obturation technique showed the largest volume of gutta-percha (p = 0.011) with an average of 67.27 ± 25.61 mm3. The lateral condensation technique showed a higher volume of voids (29.91 ± 15.37 mm3). Axis 2: The highest temperature of removal of the gutta-percha observed was 15 seconds after the end of the Largo technique with a median of 20.3 ° C (Q2513.5- Q7527.7). Conclusions: The temperature increase generated by filling techniques is within the acceptable limits. There was no statistical difference between endodontic filling techniques for void volume. Higher volume of endodontic cement was observed in the single cone and lateral condensation techniques. The temperature variation caused by the Largo instrument generated an increase in the root surface temperature above that considered safe.