牙本質結構與牙齒修補材料之固態核共振研究

本篇論文主要卓重於利用固態核磁共振(solid-state NMR)的技術來研究磷酸鈣相關之生物成礦(biomineral)與其相關之材料的合成。在第三章中，以牙齒填補材料的合成為主。無機聚合物(geopolymer)是一種鋁矽酸鹽的材料，其前趨物的來源主要為天然礦物或其它性質類似的材料，所含有的雜質不一，因此在生醫方面的利用價值較低。在此，我們先以溶膠–凝膠法(sol-gel method)製備出不含雜質之高嶺土作為無機聚合物的前趨物，並進行一系列的光譜研究來確認其性質。我們所得到的結果與利用市售天然高嶺土所製備出的無機聚合物性質非常接近，而且在外觀上為白色的色澤較於高嶺土的黃色色澤更適合應用於牙齒修補上。第二個部分主要卓重在磷酸鈣礦物的研究。在第四章中，我們利用水熱法成功的合成出高結晶性的含有鎂離子取代的氫氧基磷灰石(hydroxyapatite)，並且將鎂離子的含量控制在1∼2 wt%之間，來模擬生物樣品。由於鎂離子在磷酸鈣礦物的生長過程中具有重要的影響力，我們可以比較鎂取代標準品與生物樣品之間的差異性進而判斷鎂離子在晶格中取代的位置。第五、六章中，主要研究的是不同年齡層的大鼠(Wistar rat )與人類之牙本質樣品。跟據不同的脈衝技術所得到的數據，我們發現在老鼠的牙本質中，可區分出三種磷，分別為hydroxyapatite (HAp)、OH-deficient apatite (HDAp)、與amorphous calcium phosphate (ACP)。隨著老鼠年齡的增加，磷的總含量趨於減少，而其減少部分的主要來自於ACP部分的降低。而老鼠牙齒的成長速度也隨著年齡的上升而下降的，因此我們推論ACP在牙齒生長上扮演很重要的角色。進一步的利用另一套NMR的技巧，我們推論，這三種磷彼此之間的相對排列是以HAp為核心，周圍以一層HDAp包覆，而最外圍是非結晶相的ACP基質。將同樣的技術套用到人類牙本質樣品上，同樣可以發現這三種磷。然而人類牙本質中，三種磷的含量並沒有明顯的增減情況，此項特性也符合臨床上人類牙齒的生長特性。此外我們發現人類牙本質中ACP基質的含量僅有大鼠的一半，因此，可以推論出老鼠、與人類牙質生成速度上的差異性，再次驗證ACP在牙齒發育上所扮演的重要性。

關鍵字

牙本質結構；氫氧基磷灰石；無機聚合物；高嶺土；溶膠-凝膠法；鋁矽酸鹽

並列摘要

The main subject of this thesis is focused on the study of calcium phosphate biominerals using novel solid-state NRM techniques and the synthesis of the related materials. Geopolymer is a material based on aluminosilicates. In chapter 3, the sol-gel method is used to synthesize precursor materials for the preparation of geopolymers. The results are very similar to those obtained for the geopolymers prepared from natural kaolinite. The well-defined chemical composition in this synthetic approach offers a good opportunity for the mechanistic studies and medical applications in the future. In chapter 4, magnesium-substituted hydroxyapatite of high crystallinity is prepared as a model compound for the 25Mg high-field solid state NMR study. The study of this model compound will help us to solve the problem of the location of magnesium. In chapter 5 and 6, the structure of Wistar rat dentin and human dentin were studied by varieties of spectroscopic techniques, especially emphasize on the solid-state NMR method. The phosphorus structures of rat dentin, base on the solid-state NMR data, could be distinct into three species, viz. hydroxyapatite (HAp), hydroxyl-deficient apatite (HDAp) and amorphous calcium phosphates. We find that the amount of amorphous matrix (ACP) decreased upon the rat age. Because the growing rate of rat incisor decreased with age as well as the amorphous matrix content, it is reasonable to deduce that the amorphous matrix of dentin plays an important role for the teeth growth. Moreover, we find that the apatite crystal is a core-shell structure, with HAp surround by HDAp, embedded in the amorphous matrix. Finally, the human dentin with different ages is studied by the strategies which have been applied on Wistar rat dentin. However, no significant changes on the phosphorus units are observed. This result is consistent with the clinical observation because the growth of human teeth nearly stops after the tooth mature. Besides, the ACP content of human dentin is only half the amounts of that in rat dentin. This is also an evidence showing that the different growing rate of the rat dentin and the human dentin.

並列關鍵字

dentin structure ； hydroxyapatite ； calcium phosphate ； geopolymer ； kaolinite ； sol-gel method ； aluminosilicates

參考文獻

(60) Meyers, M. A.; Chen, P.-Y.; Lin, A. Y.-M.; Seki, Y. Progess in Materials Science 2008, 53, 1 - 206.

(69) Cho, G. Y.; Wu, Y. T.; Ackerman, J. L. Science 2003, 300, 1123 - 1127.

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(151) Tseng, Y. H.; Mou, C. Y.; Chan, J. C. C. Journal of the American Chemical Society 2006, 128, 6909 - 6918.

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牙本質結構與牙齒修補材料之固態核共振研究

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