# In Vitro Evaluation of Root Surface Temperature Using Different Endodontic Filling Techniques
## 4 Discussion
This particularly concerns the canals of the inferior mandibular incisors and the mesial canals in the inferior molars. Inferior mandibular incisors were also included in the present study, but excessive temperature rise over 10 \({}^{\circ}\)C was not observed in any of the samples. It can therefore be concluded that when the periodontal blood flow is taken into consideration, warm obturation methods can also be performed in inferior mandibular incisors without further precautions. In the present study, all of the obturation methods were performed after sealer had been applied in the root canal, which may also lead to smaller temperature increases. Studies investigating tooth surface temperatures during the application of different obturation methods have reported that using sealer reduces the temperature rise on the outer surface by up to 1 \({}^{\circ}\)C [34; 35]. Although a sealer was used, the results of this study still show an increase in temperature due to the use of heated instruments. To investigate the cooling effect of a sealer, the setup used in the present study could also provide the basis for examining different obturation methods with and without sealer. A Finite Element Analysis (FEA) study comparing warm obturation techniques with and without a simulated periodontal blood flow concluded that warm obturations carried out with a simulated periodontal blood flow resulted in a lower overall temperature increase when compared to those without simulated periodontal blood flow [18]. The highest temperature recorded was 46.5 \({}^{\circ}\)C in the mesiolingual canal. Another FEA study confirmed these findings and reported that the highest temperature rise, up to 50.048 \({}^{\circ}\)C, was at the bifurcation [36]. A molar was chosen as the model in both FEA studies. For further research, the methods used in the present study could also be applied to multirooted teeth to investigate temperature rise in different roots or bifurcations. In order to implement this, further development of the methodology is required to be able to include multi-rooted teeth. Moreover, the thermal imaging camera must be able to capture various areas such as the function, several roots and areas of curvature in multi-rooted teeth. FEA is an approximation method that relies solely on numerical calculations, and it can be difficult to gauge its divergence precisely from real conditions. The foundation of FEA assumes linear relationships. However, heat development is an exponential process, which means FEA can only approximate it. A major advantage of FEA is its ability to account for heating over the entire surface, unlike the present study, which selected specific points to represent different sections of the root. Therefore, the present study is limited to a two-dimensional perspective. However, it benefits from the real-time recording of heat development using a thermal imaging camera (VarioCAM HD; InfraTec GmbH, Dresden, Germany). FEA studies focus on a single specimen, neglecting individual variations such as dentin thickness, which can vary significantly between individuals. In addition, the cementum was not incorporated into the FEA model. In contrast, human dental material was used in this study so that a certain variance from factors such as age and gender could be taken into account. In addition, the obturation was performed by a human practitioner, which reflects real clinical practice. This has both advantages and disadvantages, as individual patient needs must be considered in clinical situations, and the approach will be influenced by the patient's tolerance and specific circumstances. The operator's experience must also be taken into account, since there are differences between obturation carried out by specialists or students [37]. In order to limit this factor in the present study, a general practitioner without specialization performed the obturation to ensure the generalizability of the data. The FEA study mentioned above examined a single blood flow rate.