The thermomechanical properties of gutta-percha. Part V. Volume changes in bulk gutta-percha as a function of temperature and its relationship to molecular phase transformation.

A variety of gutta-percha materials was subjected to dilatometric analysis to measure volume changes which take place with heating and cooling. The volume changes were found to be related directly to the molecular transformation kinetics of the polymer material and to the temperature ranges within which they take place. If the gutta-percha in the apical segment is not elevated above 45 degrees C, molecular transformation is avoided and the ultimate volume changes which accompany temperature cycling are small, predictable, and controllable.