臨床研究指出，飲食後口腔中的酸鹼值降低，酸性會影響牙齒的礦物質密度，其攸關牙齒的機械性質，包括：硬度、抗磨耗性、楊氏係數等等，因此在臨床上，牙齒礦物質密度為牙齒健康狀況的指標。目前牙齒礦物質密度的相關研究，大多屬於破壞性的方法，無法針對牙齒礦物質密度進行長期追蹤，因此本研究藉由非破壞性的高解析度電腦斷層掃描儀，分析經過酸蝕與漂白後之牙齒礦物質密度以及影響深度，此外，隨著時間的變化牙齒礦物質密度，並將其量化及進行長期追蹤，希望能更了解牙齒去礦化速度以及影響深度等等之機制。
實驗研究目的為發展一個使用高解析度電腦斷層掃描儀進行體外分析牙齒接觸不同酸性物質後的礦物質密度改變。由於高解析度電腦斷層掃描儀是屬於非破壞樣本的量測儀器，利用這種非破壞性的量測方式，可以持續追蹤經過處理前中後樣本的礦物質密度變化，為了比較樣本在不同時間所獲得影像資料的同一位置，本研究使用影像處理中的三維模型對位方法，將不同時間得到的資料進行影像對位，經過對位校準之後，得以量測評估比較牙齒同一位置的變化。
本研究結果顯示利用三維模型重新對位的方式對量測牛牙型態與礦物質密度變化的評估具有其可行性。連續使用1%檸檬酸(酸鹼值為3)酸蝕牛牙三天，酸蝕造成的物質流失在牙釉質與牙本質上分別為33及304微米，其在牙釉質與牙本質造成的損害深度分別為64微米及400微米；使用37%磷酸酸蝕牛牙15秒以及60秒的組別的組別也有被侵蝕的狀況；使用10%漂白劑的組別方面，並沒有觀察到明顯礦物質密度的變化。
本研究與其他對牙齒去礦化的研究相比，應用對位的方法可以觀察牛牙處理前中後的連續變化，發現牛牙經過檸檬酸去礦化作用之後，侵蝕的狀況非常明顯，由本研究的結果得知，若是太強烈的去礦化作用會將牙釉質或牙本質整個挖除。
本研究應用影像處理在牙齒上，將三維模型對位的方法應用於牛牙的影像資料，加上高解析度電腦斷層掃描儀非破壞性量測的特性，對持續追蹤牛牙形態與密度改變的觀察與評估是可行的。

Clinical studies indicated that the intake of acid foods or drinks would affect the mineral density of teeth which was relevant to its mechanical properties including hardness, wear resistance and Young`s modulus,etc.. The mineral density of teeth was an index of healthy on teeth. The research about the mineral density of teeth mostly belonged to destructive methods such as the hardness test. This study was to investigate the effects of acid etching and bleaching on teeth mineral density by non-destructive and high resolution computer tomography for quantification and serial long-term analysis.
In this study, bovine teeth were processed by different experiments of erosion including acid etching and bleaching. After that, three-dimensional images were obtained at different time by high resolution computed tomography. The image data was reconstructed and registered then the tooth mineral density was evaluated by selecting region of interest.
The results showed that acid etching by the citric acid (pH=3) eroded both bovine enamel and dentine. The substance loss depth in the enamel and dentin of bovine teeth after immersing in 1% citric acid for three days were 33µm and 304µm, respectively. The lesion depth in the enamel and dentin were 64µm and 400µm, respectively. The enamel and dentin of bovine teeth after immersing in 37% phosphoric acid for 15s and 60s were eroded. On the other hand, enamel and dentin in bovine teeth after immersing in 10% bleach were not observed with significant changes in mineral density.
The demineralization of citric acid on bovine teeth was significant-compared to phosphoric acid and bleaching.
The study confirmed the feasibility of micro-CT to continuously measure the mineral density in tooth by registration of three-dimensional model.

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