研發低水解聚胺酯根管封填材料：機械性質、細胞毒性及水解

Abstract

傳統根管封填材主要以馬來膠錐體搭配各類傳統封填劑，然而馬來膠錐體及各類傳統封填劑之間黏著力不足，和牙本質之黏著亦不理想，因此無法達到根管密封的目的。我研究團隊以樹酯為基底研發出聚胺酯根管封填系統，發現以PBA (polybutyleneadipate polyol)合成之聚胺酯根管封填材料在臨床操作而言有極佳的機械性質及熱性質，並且與牙本質有非常好的鍵結，可達良好密封性的目的，然而在材料接觸組織液的穩定性仍有疑慮，因此再研發以PC(polycarbonate polyol)合成之低水解聚胺酯根管封填材料。本研究目的主要在探討以PC合成之低水解封填系統材料的熱性質、機械性質及與根管牙本質間之鍵結強度，以及對聚胺酯根管封填系統材料及其他市售材料做細胞毒性及水解程度的評估。結果顯示以PC合成之聚胺酯錐體材料在熱性質方面熔點太接近體溫且稍微加熱後過於黏稠不利臨床操作；但以PC合成之胺酯壓克力樹酯封填劑在流動性是具臨床操作性的。在推離鍵結強度測試方面，以PC合成之胺酯壓克力樹酯與PBA合成之聚胺酯錐體材料的組合比其他市售材料有顯著較高的鍵結強度。在細胞毒性測試上，聚胺酯錐體在生物相容性優於馬來膠錐體，而PC合成之胺酯壓克力樹酯在完全聚合後生物相容性優於EndoREZTM，與AH plusTM相近，但PBA合成之胺酯壓克力樹酯在完全聚合後仍具細胞毒性，可能是起始劑所致。在水解程度的測試，PBA合成之聚胺酯錐體水解程度遠小於ResilonTM，而PBA及PC合成之胺酯壓克力樹酯封填劑皆有不錯的安定性。因此，依據各方面的測試，PC合成之胺酯壓克力樹酯與PBA合成之聚胺酯錐體在未來臨床根管治療的應用上深具潛力；而在PBA合成之胺酯壓克力樹酯及PC合成之聚胺酯錐體還有改善空間。

Conventional root canal materials do not have enough dentinal adhesion and can not achieve the ideal sealing properties. Our research team has developed the polyurethane root canal obturation system containing ZnO/TPU cone and dual cured urethane acrylate(UA) sealer. Although these materials has good mechanical properties and bonding strength to dentin, the cytotoxicity and hydrolytic stability are questioned. The purposes of this study was to develop the low hydrolytic polyurethane root canal obturation system by replacing the PBA polyol with PC polyol and investigate the mechanical properties、bonding strength、cytotoxicity and hydrolysis of PBA and PC-based polyurethane root canal obturation system. The results showed that the PC-based ZnO/TPU cone can not be used in humen because the low melting point, but the PC-based urethane acrylate sealer fits the clinical use. In the push-out bonding test, the results revealed that PBA-based UA sealer/ PBA-based PU cone and PC-based UA sealer/PBA-based PU cone have the higher bonding strength than other commercial products. From cytotoxicity and hydrolysis evaluations, PBA-based ZnO/TPU cones have better biocompatibility than GP cones and much lower hydrolysis than ResilonTM. The PBA-based UA sealer has good stability to hydrolysis but has high cytotoxicity even in aged specimens. We estimate the reason is that the PBA-based UA sealer does not have good interaction with the AIBN and the residual AIBN causes the cytotoxicity. The PC-based UA sealer has good stability to hydrolysis and the cytotoxicity decreased at the fresh and aged specimens. We conclude that PBA-based ZnO/TPU cones and PC-based UA sealer have high potential for clinical use, and the thermal property of PC-based ZnO/TPU cone and the initiators of PBA-based UA sealer should be improved and changed.