RESUMO
The purpose of this investigation was to compare in vitro the sealing ability of root canal treatments performed in situ with injected thermoplasticized gutta-percha compared with the lateral condensation technique. Thirty single-rooted teeth with straight canals, due for extraction for orthodontic or periodontal reasons were prepared using a step-back technique. Teeth were then divided randomly into groups A and B and obturated, respectively, with the sectional injection thermoplasticized gutta-percha and the lateral condensation techniques. Teeth were extracted after 15 days, immersed in India ink for 3 days and the leakage was determined using area-metric analysis. The roots were ground transversally and the root portion was incrementaly removed with successive steps of 250 microns each, up to the coronal level of the dye penetration. Every section was photographed with a stereoscopic microscope under the same magnification (x20); 310 photographs were taken. Measurements of the area covered by ink as well as the whole cross-sectional area of the canal were made from each photograph with the aid of a digitizing computer. The measurements were subjected to non-parametric statistical analysis. No significant difference was found (P > 0.05). The technique of lateral condensation proved to be better in the first five sections (1.2 mm from the foramen) while thermoplasticized gutta-percha technique was superior in the rest of the root canal.
