Volume shrinkage mechanism of gutta-percha point studied by differential scanning calorimetry and volume dilatometer in vitro. (February 2019)

• Record Type: Journal Article
• Authors: Dong, Mengjie; Zhang, Jichuan; Liu, Li; Yu, Yang; Yuan, Chongyang; Wang, Xiaoyan
• Is Part Of: Polymer testing. Volume 73(2019)
• Page Start: 115
• Page End: 123
• Publication Date: 2019-02
• Subjects: Gutta percha point -- Volume shrinkage -- Volume shrinkage rate -- Crystalline phase transition -- Differential scanning calorimetry; Polymers -- Testing -- Periodicals; Polymères -- Tests -- Périodiques; 620.1920287
• DOI: 10.1016/j.polymertesting.2018.10.006
• Languages: English
• ISSNs: 0142-9418

Abstract

Abstract: The mechanism of the volume shrinkage of gutta-percha (GP) point was investigated from the viewpoints of crystalline phase transition of GP and thermal expansion and contraction of thermal-conductive filler. Differential scanning calorimetry (DSC) was employed to calculate the volume shrinkage rate (VSR) of GP point indirectly by determining enthalpy changes that were caused by the crystalline phase transition. Volume dilatometer was utilized to determine the VSR directly to verify the result of DSC. The VSR of GP point calculated by DSC was approximately 2%, which was in good consistence with the result of volume dilatometer tested directly. The volume shrinkage of GP point was driven by two factors, one was the crystalline phase transition of GP that contributed to approximately 99% of the VSR of GP point, and the other was the cold contraction of thermal-conductive filler that could be ignored completely because its contribution rate was only approximately 1%. It was valuable to understand the volume shrinkage behavior of GP point materials and decrease the adverse effect of volume shrinkage in clinical therapy. Highlights: The volume shrinkage of endodontic gutta percha (GP) point is a serious problem in clinical therapy, the mechanism of the volume shrinkage is not clear. Therefore, the object of this study is to investigate the mechanism of the volume shrinkage of GP point; Differential scanning calorimetry (DSC) was employed to calculate the volume shrinkage rate (VSR) of GP point indirectly by determining enthalpy changes that were caused by the crystalline phase transition; We also analyzed the effect of crystal forms (alpha and beta) on volume shrinkage according to the results of DSC, which was one of the concerns for the dentists; Volume dilatometer was utilized to determine the VSR directly to verify the results of DSC and the mechanism aforementioned; A filling model in vitro was built to explain the generation process of the gap caused by the volume shrinkage, which further verified the mechanism of the volume shrinkage of GP point; It is valuable to understand the volume shrinkage behavior of GP point materials and decrease the adverse effect of volume shrinkage in clinical therapy.