【作者】 郑靖；

【导师】 周仲荣；

【作者基本信息】 西南交通大学 ， 机械设计及理论， 2004， 博士

【摘要】 作为一种自然的生理现象，牙齿磨损是不可避免的。随着人类平均寿命的提高，牙齿磨损引发的诸多问题日益凸现。全面了解天然牙及牙科修复材料的摩擦学特性对临床防治天然牙过度磨耗和开发新型牙科修复材料具有非常重要的理论意义和现实意义。 本文在可控气氛卧式往复滑动摩擦磨损试验机上，采用球-平面接触模式，对人体健康牙齿(乳牙和恒牙)、病理性牙齿(四环素牙)和树脂牙(三种成品树脂牙)进行了体外磨损试验。使用显微硬度仪、表面轮廓仪、激光共聚焦扫描显微镜(LCSM)、扫描电子显微镜(SEM)、电子能谱仪(EDX)、X射线光电子能谱仪(XPS)、X射线衍射分析(XRD)、傅立叶红外光谱仪等材料表面分析测试设备，系统地研究了天然牙及树脂牙的摩擦磨损行为。取得的主要结果和结论如下： 1、健康恒牙不同区域的硬度和摩擦学特性存在显著差别：与牙本质相比，牙釉质硬度高，表现出较低的摩擦系数和较好的耐磨性。此外，牙齿微观结构取向会显著影响牙齿的摩擦磨损行为，鉴于釉柱和牙本质小管的取向，同一颗牙齿在(牙合)向截面上的耐磨性优于轴向截面。 2、深入地研究了天然牙冠外层釉质的摩擦磨损行为和主要影响因素，结果表明：在摩擦接触过程中，随着釉质表面开始发生脆性剥落，磨损从两体直接接触磨损逐渐转变为三体磨粒磨损，磨损加剧；随着接触时间增长，硬质磨屑的尺寸逐渐变小，磨损率降低，进入稳定磨损阶段。微观分析结果表明，牙釉质磨损主要为机械磨损过程。此外，随着法向载荷增大，釉质的脆性本质导致磨损加剧：鉴于食物颗粒的润滑和应力分散作用，牙釉质在食物浆介质中具有较好的耐磨性，摩擦系数和磨损深度均显著低于人工唾液介质。 3、天然牙的摩擦磨损行为与年龄密切相关。年轻和中年恒牙的摩擦磨损行为较为相似，磨损表面主要呈现轻微犁削和剥落痕迹，耐磨性较好；乳牙及老年恒牙的摩擦系数变化波动较大，破坏以显著的犁削效应和大块剥落为主，耐磨性差。 4、四环素牙的摩擦学特性与其变色程度相关。与健康恒牙相比，轻度四环素牙的摩擦磨损行为无明显变化；随着变色程度加深，四环素牙的摩擦系第日页西南交通大学博士研究生学位论文数出现波动，磨损表面呈现显著的犁削效应和剥落，耐磨性降低。 5、树脂牙在人工唾液介质中同钦球对摩时表现出较好的摩擦磨损性能。随着法向咬合力增加，树脂牙的磨损机制由轻微磨粒磨损转变为严重粘着磨损，耐磨性能变差;人工唾液和碳酸饮料长期浸泡对树脂牙摩擦磨损性能影响很小;而在0一60℃温度范围内热循环老化预处理后树脂牙的耐磨性显著降低;食物颗粒导致树脂牙的耐磨性降低，在磨斑表面上犁削和剥落并存。关键词:天然牙;树脂牙;摩擦磨损;磨损机制更多还原

【Abstract】 The wear of human teeth is an inevitable physiological process. Clinical problems due to tooth wear have being increased, because people are keeping their own teeth for more years. Understanding of the tribological property of teeth would help the clinical treatment for excessive wear of teeth and develop new dental restorative materials.Normal human teeth (primary teeth and permanent teeth), pathological teeth (tetracycline stained teeth) and plastic teeth (three types of plastic teeth) have been tested under ball-on-flat contact using a reciprocating apparatus. Various analyses by using microhardness tester, profilometer, laser confocal scanning microscopy (LCSM), scanning electron microscopy (SEM), energy dispersive spectroscope (EDX), X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD) and Fouriee transform infrared spectrometer (FT-IR), have been performed. Main conclusions are drawn as follows:1. Microhardness and tribological properties differ remarkably between layers in permanent tooth. Higher microhardness, lower friction coefficient and better wear-resistance are observed in the enamel zone than in the dentin, which appears both on the occlusal section and on the axial section. Furthermore, friction and wear behaviors of tooth depend strongly on microstructure orientations. A tooth shows better wear-resistance along the occlusal section than along the axial section due to the orientation of the enamel rods and the dentinal tubule.2. Friction and wear test results show that the wear of human tooth enamel changes gradually from two-body wear into three-body wear with plastic delamination occurring on the enamel surface during wear process. With the number of cycles increasing, wear rate decreases and finally the wear of enamel stays in a stable stage. In conclusion, the wear of human tooth enamel is controlled by mechanical removal process. It is also found that increasing normal load is associated with a progressive increase in the wear volume of enamel. In addition, because of the lubrication and the stress decentralization of food slurry on the contact, enamelshows better wear-resistance in food slurry medium than in artificial saliva medium. Therefore, both low friction coefficient and small wear depth can be observed in food slurry medium.3. Tribological behavior of human tooth depends strongly upon its age. The friction and wear behaviors of permanent teeth at the young age are similar to those of permanent teeth at the middle age, and the worn surfaces are characterized mainly by slight plough and delamination traces, which have better wear-resistance. However, significant plough and massive delamination are dominant for the primary teeth and permanent teeth at the old age, accompanying with strong fluctuation in the evolution of friction coefficient.4. Tribological properties of tetracycline stained teeth are found to be correlative with its color. Friction and wear behaviors of lightly tetracycline stained teeth are similar to those of normal permanent teeth. For heavily tetracycline stained teeth, strong fluctuation and rather high stable value are found in the evolution of friction coefficient, and significant plough and delamination are dominant on the wear scar, whose tribological properties are inferior to normal permanent teeth. It is suggested that the resistance against wear of human teeth decreases with the increase of tetracycline stained extent.5. Plastic teeth are found to have good friction and wear properties sliding against titanium ball in artificial saliva medium. They are characterized by mild abrasive wear at relatively small normal loads and by severe adhesive wear at high normal loads. The immersion of plastic teeth samples in the artificial saliva or carbon beverage has little effect on the tribological properties. However, the thermally cycling of plastic teeth samples within 0-60 leads to a significant decrease in the wear-resistance. Furthermore, plastic teeth are more readily worn away by food particles. In this case, plough and更多还原