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

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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.