研發聚胺酯根管封填材料：熱、機械性質和鍵結強度

Abstract

傳統根管封填材中，馬來膠長久以來居於主流地位。研究顯示雖然各種封填系統不斷地發展，馬來膠與各式封填劑終究沒有合適根管封填技術可搭配，而得以提供適當的根管系統密封性。馬來膠對於牙本質並無黏著效果，機械強度不足而易彎折變形；且當加溫冷卻或使用溶劑揮發時，還得面臨體積收縮。為了要達到與牙本質鍵結的目的，必須藉助高分子工程的專業技術，發展以樹酯為基底的替代封填材料。如此既可提供良好的密封性，也許還可強化根管治療後的齒質。我研究團隊已初步研發出新型高分子根管封填系統，以熱塑型聚胺酯為材料基質，並使用氧化鋅為填料，成為應用於牙科根管封填錐體之氧化鋅及聚胺酯複合材料。而根管封填劑部份，則利用可見光可硬化之胺酯壓克力樹酯做為基質，並使用三丙烯乙二醇雙丙烯酸酯做為稀釋單體，以提高胺酯壓克力樹酯於牙科根管封填劑上之基本需求。本研究的目的主要在探討新型熱塑型聚胺酯根管封填系統與與市售根管封填材料在熱性質、機械性質以及與根管牙本質間之鍵結強度，作為評估新型根管封填系統於臨床應用與操作的可行性。結果顯示在機械性質方面，氧化鋅聚胺酯複合材料已明顯超越市售封填材；而在熱性質方面也具有相似於臨床材料之熔點以及較低的熔化熱。同時在推離鍵結強度測試方面，胺酯壓克力樹酯/ 氧化鋅聚胺酯複合材料的搭配為具有最高鍵結強度的組別。於掃描式電子顯微鏡的觀察，以胺酯壓克力樹酯為基底的封填劑能流入牙本質小管。因此，不論機械性質、熱性質以及鍵結強度方面，以氧化鋅聚胺酯複合材與胺酯壓克力樹酯材料做為根管封填材，在未來臨床根管治療的應用上深具潛力。

The commonly obturation material used in conventional endodontics is gutta-percha (GP). Although various obturation systems have been developed, studies with using GP and sealers have revealed that no suitable technique can offer an adequate seal of the root canal system. GP has no dentinal adhesion, lacks sufficient rigidity, and shrinks after thermal obturation. In order to achieve the aim of dentin bonding, the employment of polymer technology have led to the recent development of resin-based obturation materials. Our research team has developed a novel polymer-based root canal obturation system. Thermoplastic polyurethane (TPU) was synthesized and zinc oxide (ZnO) was used as fillers to form the ZnO/ TPU composite. For the resin part of sealer, visible-light photopolymerizable urethane-acrylate (UA) oligomer was synthesized and mixed with dilute monomer to form UA/ TPGDA resin. The purpose of this study was to investigate the thermal, mechanical properties and bonding strength of TPU polymer-based obturation materials as well as commercial polymer-based obturation materials. The results showed that tensile strength and elastic modulus of the ZnO/TPU composites were higher than that of GP and Resilon. Enthalpy change of the ZnO/TPU composite during phase transition was similar to GP but lower than Resilon. For the push-out bonding test, the results revealed that the group of UA/ PU had the highest bonding strength among test materials. From the micrographs of SEM, UA based sealer was able to flow into dentinal tubules. Therefore, ZnO/TPU composite and UA oligomer have great potential in the materials of root canal obturation, no matter in mechanical, thermal properties or bonding strength.