Evaluation of the effect of heat on root surface during the continuous wave condensation technique by finite element analysis

.109- SUMMARY The purpose of this study was to evaluate the thermal effects of continuous heat obturation technique on the tooth and surrounding tissues by using a three dimensional finite element method. In this study the temperature changes in periodontal ligament and bone tissues of a maxillary canine tooth, which had a root canal obturated with continuous heat obturation technique, were analyzed by using a three dimensional finite element method. The finite element model of the maxillary canine tooth was prepared with MSC/PATRAN® software by using data from Wheeler65. The obturation of the root canal was assumed to be done with System B heat source. Analysis of the heat transfer during the obturation was analyzed with MSC/NASTRAN® software. Periodontal ligament, enamel, dentine, cement, spongeous and compact bones were first assumed to have an average body temperature of 36°C. In order to simulate an ongoing root canal treatment process, the free heat convection from mouth was also assumed to take place. The ambient temperature was taken as 22°C. As a first step, 5 mm gutta percha was placed at the apical region. Then, 200°C heat was applied to a portion of gutta percha in order to simulate System B heat source application and the tooth and surrounding tissues were let to cool down for 5 seconds. During these steps, the temperatures of all the elements were changed. In the second step another 4 mm gutta percha in room temperature was added to the root canal. In the third step, in accordance with the vertical condensation technique, 100°C heat was applied to the additionally placed gutta percha and again it was let to cool down for another 5 seconds. Following similar steps, the root canal was increamentally obturated in seven steps. In each step, the temperature changes of all elements were determined.-1 10- ln the second stage of the study the first step, which was determined to be the most critical one, was repeated for a 250°C initial setting of System B heat source. it was found that, when the initial setting of System B heat source is 250°C, the temperature increase in periodontal ligament reaches to the critical 10°C value.