[3,13,24,25] Despite the relevance and importance of the Enzastaurin manufacturer X-ray, microanalysis and diffraction techniques in the screening of some chemical elements and compounds present in GP brands, there are some limitations to the use of these techniques for quantitative analysis. For rigorous quantitative X-ray microanalysis, the atomic number of the analyzed element must be greater than 11. Thus, important elements such as hydrogen, carbon, nitrogen and oxygen could not be correctly quantified. In addition, the element concentration has to be greater than 5% and the specimen must be homogeneous in the volume sampled.[22,24,25] Assumptions concerning the relative contents of elements present in the material were made based on the results and zinc was found to be universally present in large amounts.

These results indicate that zinc oxide is the main ingredient in these brands, which is in accordance with many studies.[3,6,9,13,23] Despite the differences in chemical compositions of the materials analyzed, there were no differences in their thermal behavior. This fact leads us to believe that gutta-percha percentages above 15% of the chemical composition probably determine the thermal behavior of the sample. In the present study, all specimens showed two typical major endothermic peaks in the first DSC run [Table 3], indicating that they are a ��-form material. These results are in line with the data obtained by Schilder et al.[18] and Maniglia-Ferreira et al.;[19] however, during the second run, no peaks occurred at a temperature higher than 53.7��C, which contradicts the findings of Combe et al.

[21] DSC allows for an appraisal of the estimated thermal range required to plasticize GP between 40��C and 60��C.[17] In endodontic therapy, dental GP is plasticized by a heat carrier (System B, Obtura II, Thermafil and Microseal microflow) or by Thermomechanical compaction (Microseal cone), which heats to a temperature higher than the maximum allowed to avoid partial degradation (100��C), according to the Merck index[26] and Maniglia-Ferreira et al.[27] The low fusion temperature of the tested materials is due to the high percentage of organic compounds in their composition (GP and wax/resins). The high quantities of wax and resins found in TH, OBF and MF can jeopardize the longevity of the endodontic treatment, as they are easily degraded, damaging the dimensional stability of the obturation material.

[19,25,27,28] Our DSC results, which are similar Entinostat to those of Schilder et al.,[18] indicated that GP in the ��-phase begins its transition to ��-phase when heated from 51��C to 53��C, and the ��-phase material begins its transition to an amorphous phase when heated between 60��C and 62��C. Our results suggest that after the material has cooled off and is heated up again, beginning a new heating cycle, the amorphous GP finds itself crystallized into the ��-phase and is therefore, not able to return to the ��-phase.