Development of new method for root canal filling using the shape memory polymer

用交联的聚过胶（反式聚异戊二烯）制备了形状记忆聚合物。以硫和过氧化二氨基为交联剂，氧化锌和硬脂酸为交联促进剂。证明了交联桃胶的形状记忆机理。通过交联记忆的试样在超过过渡温度的加热下容易变形。该变形试样在转变温度下冷却，通过反式聚异戊二烯结晶固定试样形状。通过超转变温度加热，可以使固定形状恢复到原来的形状。这种行为是根据反式聚异戊二烯的熔融结晶。修复温度可通过加入顺式聚异戊二烯或交联剂来调节。修复温度可设定在低于口内温度。随着交联剂用量的增加，弹性模量增大，顺式聚异戊二烯用量的增加，弹性模量减小。采用形状记忆聚合物制备根管充填点，并进行充填试验。填充根管采用玻璃管、牛牙根管和丙烯酸酯人工根管。采用形状记忆聚合物对玻璃管进行密封试验，密封效果良好，密封时间长达18个月。形状记忆聚合物的密封效果优于垂直凝结法。用形状记忆聚合物对130号扩眼器扩大的人工根管进行了密封试验，结果表明其密封效果较好。

The shape memory polymer was produced by using the closs-linked gutta percah (trans polyisoprene). The Sulfur and Dicumyl peroxide were compounded for cross-linking agent, Zinc oxide and Stearic acid were compounded for cross-linking promoter. The mechanism of shape memory for closs-linked gutta percah was proved following. The test specimen that was memorized for original shape by cross-linking could be deformed easily by heating at over the transition temperature. This deformed specimen was cooled at under the transition temperature and the shape of specimen was fixed by crystallization by trans polyisoprene. The fixed shape could restore to original shape by means of the heating at over the transition temperature. This behavior was according to the melting of the crystallization of trans polyisoprene. The restoration temperature could be adjusted by the addition of cis polyisoprene or cross-linking agent. And the restoration temperature could be established at under the intra-oral temperature. As addition of the cross-linking agent increased the elastic modulus increased, and as addition of the cis polyisoprene increased the elastic modulus decreased. The point for root canal filling was produced by using the shape memory polymer and the sealing test was conducted using it. The canal for filling was used glass tube, root canal for bovine tooth and artificial root canal produced by acryl. The sealing test for glass tube using the shape memory polymer was shown superior sealing for eighteen months. The sealing test using the shape memory polymer was shown to be more superior to that using the vertical condensation method. The sealing test using the shape memory polymer for the artificial root canal which was enlarged by using #130 reamer was showed to be superior sealing.