The mechanism of synergistic effect between wear and microbe corrosion in the degradation process of dental materials

本研究的目的是开发测试方法，以评估口腔中暴露于微生物腐蚀和牙齿碰撞引起的机械力的联合攻击的牙科材料。动态磨损条件的确定：使用载荷传感器（Tekscan）测量咀嚼软、硬食物时牙齿上产生的应力，得到最大载荷范围、加载速度和接触时间，其范围分别为4-13 kgf、0.03-0.07 kgf/ms、420-500 ms.口腔材料的降解过程及降解指标：考虑到牙体高度降低导致的牙体接触不良，选择牙体高度降低作为降解指标.试验方法的发展：对于金属材料，通过平板（试件）和球体（Al_2O_3）的组合来模拟牙齿接触。重复载荷通过t施加 ...更多信息 在试样表面产生压痕，压痕直径与压痕深度成正比，即齿高减小，齿高随加载时间的增加而增加，与加载频率成指数函数关系，这与位错的延迟运动有关。在3%NaCl溶液中的试验结果很好地反映了金属材料在磨损和腐蚀联合作用下的特性。对于牙科树脂材料，由于它是由三种不同类型的树脂组成的复合材料，因此使用了一整片假牙作为试验样品。多次碰撞试验表明，齿高的降低不是由于磨损而是由于整个齿片的变形引起的，其次，在碰撞频率约为5万次时，变形行为发生了变化，三是低载荷的多次碰撞试验揭示了材料不同于高载荷的一次加载试验的特性.在此基础上，提出了口腔环境下牙科材料的测试方法。少

The purpose of this investigation is to develop testing methods to evaluate dental materials that are exposed in mouth to the combined attack of microbe corrosion and mechanical forces that are caused through the collision of teeth.1. The determination of dynamic wear condition : Stresses which are originated on teeth while chewing soft or hard foods were determined by use of a load sensor (Tekscan) to obtain the extent of the maximum load, loading speed and the contact duration, which were ranged from 4-13 kgf, 0.03-0.07 kgf/ms, 420-500 ms respectively.2. The degradation process of dental materials and the index of degradation : The delinquent in teeth meeting due the decrease in teeth height was taken up so that the decrease in the teeth height was chosen as the index of degradation.3. Development of testing method : As to metallic materials, the teeth meeting were simulated through the combination of a flat plate (specimen) and a sphere (Al_2O_3). Repeated load was applied through t … More he sphere to the specimen to produce an indentation on the surface of which diameter is proportional to the depth of indentation, that is, the decrease in teeth height.It increased with the test duration as an exponential function of loading frequency, which revealed some relation with the delayed movement of dislocation. Those test results obtained in a 3 % NaCl solution were proved to represent well the characteristic behavior of metallic materials that are exposed to the combined attack of wear and corrosion.As to dental resin materials, a whole piece of false tooth was used as test specimen because it is a composite that consists of three different types of resin. Repeated collision test revealed firstly that the decrease in teeth height is caused not through wear but through the deformation of whole tooth piece, secondly that the deformation behavior changes its manner at the collision frequency of about 50000 times, and thirdly that the repeated collision test with low load reveals a characteristic behavior of material different from that of a single time loading test with a much higher load.4. Basing on the test results, a new test method for the dental materials in mouth environment were proposed. Less