人類牙齒屬於天然非等向性的材料，能有很好的力學表現，其研究能被應用在複合材料及生醫材料當中。牙齒經常承受不同荷重的負載以及其所帶來的應力，除承受上下咬合力的正向力外，在咀嚼與牙齒間的相互摩擦中，會使得牙齒外層琺瑯質也承受橫向的剪應力。「酸」對牙齒的磨損會加速牙齒的蛀牙率。在蛀牙問題中，最嚴重的就是長期飲用如可樂、雪碧等碳酸飲料所造成。因此本研究向診所取得蛀牙牙齒後，先進行不同類型牙齒(犬齒、前臼齒、第一大臼齒、第二大臼齒)在其縱切面與橫切面運用奈米壓痕實驗機作機械性質探討，以了解不同類型牙齒的結構及其物理意義。再利用不同碳酸飲料進行牙齒酸蝕實驗，並探討其酸蝕前後的機械性質與運用場發射槍掃描式電子顯微鏡作表面形貌差異、原子力顯微鏡作粗糙度的對照比較，我們也用酸鹼量測計量測其酸鹼值的變化。
實驗結果顯示不同部位牙齒其損壞程度不同，四種牙齒除犬齒外，在橫切面的平均硬度大約650MPa，推測為琺瑯質，然而犬齒硬度較低大約為410MPa，可能為診所取得犬齒磨損較嚴重。而四種牙齒在縱切面硬度大小為第二大臼齒>前臼齒>第一大臼齒>犬齒 ，其中第一大臼齒硬度小於第二大臼齒，是因為第一大臼齒為人類絞碎食物時最常使用的牙齒，導致牙齒琺瑯質磨損較嚴重，犬齒最外層尖銳處較易磨損，推測壓痕實驗均打在牙本質上，故硬度最低。藉由四種牙齒在縱切面與橫切面的機械性質說明了人類不同部位牙齒因在咀嚼功能角色不一，導致其磨損程度不同。
另一方面，從牙齒酸蝕實驗的結果發現四種牙齒在不同碳酸飲料中有不一樣的機制，結果顯示Coke對四種牙齒在酸蝕反應前期速率較快，後期較慢，而Sprite對四種牙齒酸蝕呈現線性下降的趨勢，Mountain Dew對四種牙齒在酸蝕前期較慢，酸蝕後期較快。且在酸蝕反應的過程中，也能看出牙齒機械性質的下降與pH值的變化有關。綜合以上實驗的結果能提供生醫領域在研發生醫複合材料的數值及受損修復上作為參考。

Human teeth are hierarchical and anisotropic materials that can withstand high stress during crushing and grinding in mastication. Each tooth has specific shapes to aid the function. Even though each tooth is made up of same components, different function and shape makes each tooth undergoes different loading in mastication which leads to various wear state. Besides mastication, acid etching from carbonated drinks is another important factor for hardness loss. In this thesis, we take four different kinds of tooth (canine, premolar, first molar and second molar) from various dental clinics and study the mechanical properties (hardness and elastic modulus) associated with each tooth. After elastic properties measurement, these teeth were immersed in Coke, Sprite and Mountain Dew drinks for acid test. The mechanical properties were evaluated by nanoindentaiton. The surface morphology and roughness were examined by SEM and AFM, respectively. The teeth were evaluated by mechanical properties variation.
The results show the mechanical properties are distinct in each tooth. For horizontal cross-section measurements, the average hardness is 650 MPa for premolar, first molar and second molar and is 410 MPa for canine. For vertical cross-section measurements, the order of average hardness is second molar > premolar > first molar > canine. The low hardness of canine is due to the fact that canine is under intermittent contact with other teeth during mastication. As a result, the erosion of enamel leads to the loss of hardness. Similarly, first molar has more contact in mastication also results in hardness reduction. The distinct role in each tooth under mastication is the reason why different tooth exhibits different hardness.
For acid etching, the response curve is different for different drink. For Coke, the erosion rate is fast in the beginning and then reduces after 3 hrs. Sprite has linear erosion rate during the whole process. The erosion begins after 6 hr for Mountain Dew. The hardness reduction during the erosion is accompanied by the increase of pH. The loss of calcium phosphate is the primary mechanism for teeth under carbonated drink acid etching.
In conclusion, the role of each tooth in mastication is exhibited by the mechanical properties. Canine seems to have the most wear rate and lowest hardness. Calcium phosphate loss is the mechanism for hardness reduction. The erosion rate depends on the type of carbonated drinks.

誌謝i
摘要ii
ABSTRACTiv
目錄vi
圖目錄viii
表目錄xiii
第一章 序論1
1.1 前言1
1.2 研究動機與目的2
1.3 文獻探討4
第二章 實驗原理9
2.1 奈米壓痕實驗9
2.1.1 影響奈米壓痕量測因素11
2.2牙齒酸蝕實驗14
2.3牙齒再礦化實驗 16
第三章 研究方法17
3.1 牙齒分類處理17
3.2牙齒試件鑲埋製作18
3.3 牙齒壓痕實驗20
3.4牙齒酸蝕實驗23
3.5牙齒試件表面形貌量測25
3.6實驗流程與架構 27
第四章 蛀牙牙齒機械性質29
4.1 犬齒蛀牙牙齒機械性質29
4.2 前臼齒蛀牙牙齒機械性質39
4.3 第一大臼齒蛀牙牙齒橫切面機械性質48
4.4 第二大臼齒蛀牙牙齒橫切面機械性質57
4.5 不同牙齒機械性質綜合比較66
第五章 不同牙齒酸蝕情形72
5.1牙齒Coke酸蝕情形72
5.2牙齒Sprite酸蝕情形80
5.3牙齒Mountain Dew酸蝕情形88
5.4 不同碳酸飲料對牙齒酸蝕比較96
5.4.1 不同牙齒對碳酸飲料酸蝕比較101
5.5 前臼齒酸蝕後再礦化情形105
第六章 結論107
參考文獻 108

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