Gakuji Tsukada1, Masayuki Tokuda2, Mitsuo Torii2. 1. Department of Restorative Dentistry and Endodontology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan. Electronic address: tsukada@dent.kagoshima-u.ac.jp. 2. Department of Restorative Dentistry and Endodontology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
Abstract
INTRODUCTION: Pure gutta-percha (trans-1, 4-polyisoprene [TPI]) has been used extensively as a main component of gutta-percha for root canal filling. TPI has the interesting shape memory property by cross-linking, and this polymer was commercialized under the product name of SMP-2 (Kuraray Corp, Kashima, Japan). Therefore, the purpose of this study was to examine the thermal properties and the mechanism of the shape memory function of cross-linked SMP-2. METHODS: The crystalline of the TPI was observed by x-ray diffraction. The effects of temperature on shape recovery, recovery stress, and relaxation modulus (Er[5]) were measured in cross-linked cylindrical specimens of SMP-2. Differential scanning calorimetry was used to monitor thermal events. RESULTS: On heating, a pronounced increase in recovery stress, a marked decrease in Er(5), and endothermic DSC peaks were observed over the same temperature range (38°-51°C) with shape recovery. On the other hand, on cooling, a pronounced decrease in recovery stress, a marked increase in Er(5), and an exothermic DSC peak were observed over the same temperature range (27°-33°C). CONCLUSIONS: The shape memory property of TPI is derived from its crystallinity and cross-linking ability. Fixing the deformed shape and shape recovery from the deformed shape to the original shape is relatively easy to achieve by changing the temperature of SMP-2. The shape memory function of the cross-linked SMP-2 was expected to be very useful as a root canal filling material by the modification of its some thermal properties.
INTRODUCTION: Pure gutta-percha (trans-1, 4-polyisoprene [TPI]) has been used extensively as a main component of gutta-percha for root canal filling. TPI has the interesting shape memory property by cross-linking, and this polymer was commercialized under the product name of SMP-2 (Kuraray Corp, Kashima, Japan). Therefore, the purpose of this study was to examine the thermal properties and the mechanism of the shape memory function of cross-linked SMP-2. METHODS: The crystalline of the TPI was observed by x-ray diffraction. The effects of temperature on shape recovery, recovery stress, and relaxation modulus (Er[5]) were measured in cross-linked cylindrical specimens of SMP-2. Differential scanning calorimetry was used to monitor thermal events. RESULTS: On heating, a pronounced increase in recovery stress, a marked decrease in Er(5), and endothermic DSC peaks were observed over the same temperature range (38°-51°C) with shape recovery. On the other hand, on cooling, a pronounced decrease in recovery stress, a marked increase in Er(5), and an exothermic DSC peak were observed over the same temperature range (27°-33°C). CONCLUSIONS: The shape memory property of TPI is derived from its crystallinity and cross-linking ability. Fixing the deformed shape and shape recovery from the deformed shape to the original shape is relatively easy to achieve by changing the temperature of SMP-2. The shape memory function of the cross-linked SMP-2 was expected to be very useful as a root canal filling material by the modification of its some thermal properties.
Authors: Lu Lu Taung Mai; Min Min Aung; Sarah Anis Muhamad Saidi; Paik San H'ng; Marwah Rayung; Adila Mohamad Jaafar Journal: Polymers (Basel) Date: 2021-06-30 Impact factor: 4.329