Carbonate-type Polyurethane-based Root Canal Filling Material: Mechanical and Thermal Properties

Objectives: The objective of obturation is to create a fluid-tight seal along the length of the root canal system. A more appropriate material for root canal obturation still needs to be developed. Carbonate-type thermoplastic polyurethane exhibits good biocompatibility and hydrolysis resistance. In this study, we developed a novel carbonate-type polyurethane-based root filling material and evaluate its mechanical and thermal properties. Methods: We synthesized zinc oxide/ carbonate-type thermoplastic polyurethane (ZnO/carbonate-type TPU) composite as a root canal filling material. The mechanical and thermal properties of the ZnO/carbonate-type TPU composite, including tensile strength, elastic modulus, melting point and enthalpy change, were compared with those of gutta-percha and Resilon. Results: The tensile strength and elastic modulus of the ZnO/carbonate-type TPU composite were 23.2±3.2 Mpa and 102.4±20.2 Mpa respectively, which were markedly higher than those of gutta-percha and Resilon. The melting point of the ZnO/carbonate-type TPU composite (48.6℃) was lower than gutta-percha (61.3℃) and Resilon (64.2℃), however, the enthalpy change of ZnO/ carbonate-type TPU (26.62 J/g) were lower to those of Resilon (28.9 J/g) but higher than those of gutta-percha (10.9 J/g). Conclusions: The results indicate that ZnO/carbonate-type TPU composite exhibits better mechanical strength and it require lower thermal energy than Resilon. Therefore, ZnO/carbonate-type TPU composite has strong potential to be used as root canal filling material.