Heat transfers to periodontal tissues and gutta-percha during thermoplasticized root canal obturation in a finite element analysis model

Objectives. The aim of this study was to measure the temperature distributions on the periodontal ligament and apical gutta-percha during thermal obturation with different plugger activation time. Study design. The multirooted model of mandibular first molar development and root canal treatment were performed by finite element analysis. The apical thirds of canals were obturated by continuous-wave condensation technique, with 3 seconds and 4 seconds of activation time. The remainder was backfilled with injected gutta-percha in 2 segments (Obtura II). Results. The highest temperatures on the periodontal ligament reached 46.914 degrees C and 48.887 degrees C, in the "dangerous zone" between the root canals, when activation times were 3 seconds and 4 seconds, respectively. The greatest temperature rise within the apical gutta-percha was only 0.859 degrees C. Conclusion. With 3 seconds of activation, the temperature elevation reached almost 47 degrees C, so one should be careful not to extend the activation time beyond 3 seconds, which is clinically difficult to control. The apical gutta-percha temperature was always below the desired level to achieve proper thermoplasticity. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 110: 257-263)