人牙釉质内有机物和水分对其微摩擦磨损行为的影响研究

发布时间：2018-03-20 08:03

本文选题：人牙釉质　切入点：微摩擦磨损　出处：《西南交通大学》2012年硕士论文　论文类型：学位论文

【摘要】：牙齿是人体消化系统中的重要器官,优异的摩擦学特性是其行使生理功能的保证。牙齿主要由牙釉质、牙本质和牙髓腔构成,其中,外层的牙釉质是人体内最硬的组织,对咀嚼磨耗有较大的抵抗力。牙釉质由占总重量96-97%的无机物以及1-2%有机物和3-4%水所组成。人牙釉质是目前尚无法人工复制的一种天然生物材料,研究釉质化学组成及其内部独特的天然微结构对其摩擦磨损行为的影响,不仅可以深化对天然生物材料的科学认识,而且可以丰富生物摩擦学和仿生摩擦学的基础知识,为牙科修复材料的仿生设计提供理论基础。本论文采用纳米划痕、纳米压痕等微纳米摩擦学测试手段,研究了人牙釉质内有机物和水分含量对其微摩擦磨损行为的影响,旨在分析人牙釉质中有机物和水分与其摩擦磨损机制的关系。研究取得的主要结果和结论如下： 1、经次氯酸钠水溶液萃取表层有机物后,人牙釉质表面的纳米压痕硬度无明显变化；在萃取初期,人牙釉质表面的弹性模量迅速减小,随后减小速度明显变缓,最后趋于稳定。纳米划痕测试结果显示,人牙釉质表面的摩擦系数随萃取时间增长略有减小,波动加剧；人牙釉质表面的划痕深度随萃取时间增长而增大,釉质磨损加剧。通过SEM图可以看出,次氯酸钠萃取有机相时间的增长,表面出现隆起,逐渐呈现明显的磨屑及材料去除现象,由划痕沟槽内往沟槽外扩展堆积。进一步的微观分析结果还显示,经次氯酸钠水溶液萃取表层有机物后,釉质内的羟基磷灰石颗粒尺寸变大。 2、人牙釉质表层的含水量对其纳米力学性能和微摩擦磨损行为存在显著影响。随着干燥时间增长,牙釉质表面的弹性模量减小,纳米压痕硬度增大。纳米划痕实验结果显示,随着干燥时间增长,牙釉质表面摩擦系数增大,且呈现显著波动,划痕深度增加,磨损加剧。微观分析结果显示,经干燥脱水处理后,人牙釉质表层局部出现空隙,干燥时间越长,空隙越明显。可见,人牙釉质内的水分对其具有明显的润滑作用,可以减小釉质表面的摩擦磨损。脱水干燥的人牙釉质试样经浸水处理后,其表层的摩擦磨损性能可以得到一定程度的恢复,摩擦系数和磨损量均呈现明显降低。这可能是由于溶液中的水分通过吸附在釉质表面,与釉质表层的羟基磷灰石晶体结合,构成晶体的水合外层,使得牙齿的摩擦磨损性能得以恢复。
[Abstract]:Teeth are important organs in the human digestive system, and their excellent tribological properties are the guarantee of their physiological functions. Teeth are mainly made up of enamel, dentin and pulp cavity, and the outer enamel is the hardest tissue in the human body. The enamel is made up of 96-97% inorganic material, 1-2% organic matter and 3-4% water. Human enamel is a kind of natural biological material which can not be artificially copied. The study of the chemical composition of enamel and the influence of its unique natural microstructure on its friction and wear behavior can not only deepen the scientific understanding of natural biomaterials, but also enrich the basic knowledge of biological tribology and bionic tribology. It provides a theoretical basis for the bionic design of dental restoration materials. In this paper, the effects of organic matter and moisture content in human enamel on the micro-tribological behavior of human enamel were studied by means of nano-scratch and nano-indentation. The aim of this study is to analyze the relationship between organic matter and moisture in human enamel and its friction and wear mechanism. The main results and conclusions are as follows:. 1. After the surface organic matter was extracted by sodium hypochlorite solution, the hardness of nano-indentation on the surface of human tooth enamel did not change obviously, and at the beginning of extraction, the elastic modulus of the surface of human tooth enamel decreased rapidly, then the decreasing rate of enamel surface decreased obviously. Finally, the results of nano-scratch test showed that the friction coefficient of human enamel surface decreased slightly with the increase of extraction time, and the fluctuation increased, and the scratch depth of human enamel surface increased with the increase of extraction time. The wear of enamel was aggravated. It can be seen from SEM diagram that the time of extraction organic phase of sodium hypochlorite increased, the surface appeared bulge, and gradually showed obvious wear debris and material removal phenomenon. The microcosmic analysis also showed that the size of hydroxyapatite particles in enamel increased after the surface organic matter was extracted by sodium hypochlorite solution. 2. The moisture content of human enamel surface has a significant effect on the nano-mechanical properties and micro-friction and wear behavior. With the increase of drying time, the elastic modulus of enamel surface decreases and the hardness of nano-indentation increases. With the increase of drying time, the friction coefficient of enamel surface increased, and showed obvious fluctuation, the scratch depth increased and the wear increased. The results of microcosmic analysis showed that after drying and dehydration, there was a gap in the surface of enamel. The longer the drying time is, the more obvious the void is. It can be seen that the moisture in human enamel has obvious lubricating effect on the enamel surface, which can reduce the friction and wear on the enamel surface. The friction and wear properties of the surface layer can be recovered to a certain extent, and the friction coefficient and the wear amount are decreased obviously, which may be due to the fact that the water in the solution binds to the hydroxyapatite crystal of the enamel surface by adsorption on the enamel surface. The hydrated outer layer of the crystal can restore the friction and wear properties of the teeth.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TB30;R783.1

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