Further studies on heat generation during obturation techniques involving thermally softened gutta‐percha

Summary. A study in vitro investigated the heat generated at the root face of human single‐rooted canine teeth during the use of thermally softened gutta‐percha root‐filling techniques. The temperature rise was recorded at two points on the outer surface of each tooth using thermocouples linked to a chart recorder. Four groups of specimens were used in the study. In the first group, the teeth were root filled using a plugger at a rotational speed of 8000 rev/minute. In the second group, the teeth were obturated with a plugger of the same design but at a rotational speed of 16,000 rev/minute. The third group was root filled with a combination of lateral condensation of gutta‐percha and mechanical compaction, and in the final group, filling was carried out using the Unitek Obtura system. The results showed that significant temperature rises occurred in the four groups and that these rises were greater at the central point than apically. An increase in the rotational speed of compaction caused an increased temperature rise at the apical region. The heat generated by the injection of thermally softened gutta‐percha was slower to dissipate than with the other techniques. The results of these investigations would indicate that the temperature rises generated during the use of thermally softened gutta‐percha in endodontic obturation lie within the range likely to cause tissue damage.