Effect of several thermoplastic canal filling techniques on surface temperature rise on roots with simulated internal resorption cavities: an infrared thermographic analysis.

AIM: To evaluate the surface temperature rise using an infrared thermal imaging camera on roots with and without simulated internal resorption cavities, during canal filling with injectable (Obtura II), carrier-based (Soft-Core) gutta-percha and continuous wave of condensation (System B) techniques. METHODOLOGY: Root canals of 60 mandibular premolar teeth were instrumented to an apical size of 40. Circular artificial internal resorption cavities with a diameter of 2.40 mm were prepared on the root canal walls of 30 teeth. All teeth were divided into six groups of 10 specimen and root filled as follows: group 1 (teeth with internal resorption): thermoplasticized injectable gutta-percha (Obtura II), group 2 (teeth without internal resorption): thermoplasticized injectable gutta-percha (Obtura II), group 3 (teeth with internal resorption): carrier-based gutta-percha (Soft-Core), group 4 (teeth without internal resorption): carrier-based gutta-percha (Soft-Core), group 5 (teeth with internal resorption): continuous wave of condensation (System B) and group 6 (teeth without internal resorption): continuous wave of condensation (System B). The surface temperature changes during filling of canals were measured with an infrared thermal imaging camera. The thermograms were recorded at 2-s intervals over a period of 40 s to determine the maximum temperature rise at the apical, middle and cervical thirds of the root surface. The data were statistically analysed with one-way anova and Tukey HSD post hoc or Kruskal-Wallis and Bonferroni-adjusted Mann-Whitney U-tests if appropriate. RESULTS: The temperature rise on the surface of roots with artificial resorptive defects was significantly higher compared with the ones without defects in the Obtura II and System B groups (P < 0.001). The System B group with internal resorption was associated with the maximum temperature rise in the apical (4.3 +/- 2.1) and middle (19.5 +/- 8.9) thirds amongst the groups (P < 0.001). CONCLUSION: Use of System B and Obtura II for filling canals with internal resorptive cavities resulted in surface temperature rise over the critical threshold. However, Soft-Core root filling did not increase the temperature over 10 degrees C.