A comparison of four root canal obturation methods employing gutta-percha: a computerized analysis of the internal structure.

The purpose of the present investigation was to compare the internal structure of gutta-percha for presence/absence of empty spaces when used in four different obturation methods: thermoplastic, chloroform-softened, thermomechanical, and warm lateral condensations. Each obturation was performed five times in a metal mold representing a root canal system. Following obturation the mold was disassembled and the gutta-percha was freeze-fractured at the 1.0, 3.5, and 6.5 mm levels as measured from the tip of the obturations. The fractured gutta-percha was placed in a scanning electron microscope, the image transferred to a computer, and converted to digital data. The results were subjected to statistical evaluation. The results demonstrated no difference between the obturation methods at the 1 mm level, however at the 3.5 mm level, thermomechanical condensation produced an internal structure characterized by a greater number of empty spaces (p < 0.0007). At the 6.5 mm level, thermomechanical condensation differed only from the chloroform-softened gutta-percha (p < 0.01).