研發含TGF-β1之磷酸鈣/硫酸鈣雙相水泥於活髓治療之研究 - 材料物化性質、生物活性、生物相容性及動物實驗

Abstract

活髓治療的目的在使牙髓保持活性並形成修復性牙本質，維持牙齒正常生理結構及功能。活髓治療發展至今在臨床上仍然沒有理想之材料。磷酸鈣骨水泥(CPCs)在牙科的應用主要是作為骨頭缺損的修補材料，在牙周病、顱顏手術、外傷修復、齒顎矯正等領域都有相關應用。然而，CPCs的硬化時間過長(30-60分)、材料的低機械強度造成易崩解等性質仍舊限制了其在臨床應用的發展。CPCs用於活髓治療需改善初期硬化時間太長的缺點，因此本研究改善CPCs製程使有效縮短初期硬化時間並發展可調控硬化時間之新型磷酸鈣-高分子材料應用於活髓治療。 本研究目的為改良磷酸鈣骨水泥(CPCs)生醫陶瓷材料應用於活髓治療，藉由結合磷酸鈣骨水泥(CSC)發展改良適合活髓治療可引導牙髓組織再生之新型磷酸鈣複合生醫陶瓷材料，並以聚麩胺酸-明膠結合生長因子TGF-β1添加至磷酸鈣-硫酸鈣雙相材料系統，探討與細胞組織交互作用的機轉，以及其誘導牙本質牙髓組織再生的調控模式。本研究分為四大部分，第一部分為材料物理化學性質分析包含晶相結構、固化時間、溫度變化、機械性質、降解測試與鈣離子釋放。第二部分為生物活性指標測試，以SEM與XRD鑑定水合產物結構以及所發展之生醫材料對細胞鈣化 (礦化) 的影響。第三部分為生物相容性分析，以ISO-10993標準評估細胞存活率、細胞毒性。第四部份為建立大動物實驗模型，以犬隻評估所研發之生醫材料與市售材料於牙髓組織再生之差異。 研究結果顯示，藉由添加CSC改善CPC硬化時間長的難以單獨應用於活髓治療缺點，其硬化時間由一個小時降為十五分，符合臨床操作性質，此材料具有良好的生物相容性。此外，所研發之磷酸鈣/硫酸鈣雙相材料能誘導牙本質橋的形成，而以聚麩胺酸-明膠結合生長因子TGF-β1添加至磷酸鈣-硫酸鈣雙相材料系統在一個月即能誘導完整連續之本質橋生成。

Vital pulp therapy is to preserve the pulp vitality as well as to form the reparative dentin for maintaining the normal physical structures and functions of teeth. After years of research and development of the biomaterials, not an ideal material for vital pulp therapy Bioactive calcium phosphate cements (CPC) have been widely used for repairing bone defects because of their excellent biocompatibility and bioactivity. However, the drawbacks of poor handling properties, low initial mechanical strength, and relatively long setting time limit its application in vital pulp therapy. We synthesized and evaluated the feasibility of biphasic calcium phosphate/sulfate cements for vital pulp therapy. CPC cements were mixed with various amounts of calcium sulfate cements (CSC) to improve the physical, chemical, and mechanical properties. Poly-γ-glumatic acid (γ-PGA) is suitable candidate for drug carrier. And TGF-β1 is well-known for its ability to induce differentiation of dental pulp. The CPC-CSC biphasic biomaterial combinedγ-PGA with TGF-β1 for vital pulp therapy. The purpose of this study is to understand the mechanisms underlying pulp-dentin regeneration and test the efficacy in vivo of our materials for vital pulp therapy. We examined the biphasic biomaterials to study its physicochemical properties, bioactivity, biocompatibility and animal study. The results shows that the initial setting time of CPC-CSH biphasic cement exhibited substantial improvement compared with CPC. The cell viability and cytotoxicity exhibited no harm to the dental pulp cell and animal study presents this CPC-CSH biphasic cement can induce calcified tissue. Based on the results, the developed CPC/CSH biphasic cement has great potential as a material for vital pulp therapy.