Authors: Schilder H, Goodman A, Aldrich W.
Title: 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.
Journal: Oral Surg Oral Med Oral Pathol
Date: Mar 1985
Citation: 59(3):285-96
Category: Obturation
Evidence-based Ranking: 5
Purpose/Objectives: To determine the changes in gutta percha when subjected to temperature cycling and plunge tests. Materials & Methods: Ten different brands of gutta percha were analyzed in the study. The gutta percha was subjected to temperature cycling (slow and rapid) tests in order to determine what effect, if any, these conditions had on volume change and transformation of the material. In the slow cycling tests, the GP was raised to a temperature of 80 deg C over a period of 2 hrs and was allowed to cool gradually. In rapid cycling the GP was rapidly cycled between temps of 37 deg C and 80 deg C and 37 deg C and 45 deg C, which would be more similar to a clinical situation.

Results: Results showed small volume reduction in cooling to 37 deg C in all GP brands tested. Both rapid and slow cycling data showed molecular-phase transformation if heated above 45 deg C, as well as volume reduction. AuthorÂ’s Conclusion: If gutta percha in the apical segment is not elevated above 45 deg C, molecular transformation is avoided and the ultimate volume changes which accompany temperature cycling are small, predictable and controllable. Validity of Conclusion: Conclusions are valid based on the parameters of the study. ReviewerÂ’s Comments: Good study and very applicable to any warm GP obturation technique.