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

Abstract

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. 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. 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). 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 °C.