Study On The Three-body Wear Of Human Enamel

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 three-body wear of human enamel would help the clinical treatment for excessive wear of teeth and develop new dental restorative materials.In this paper, the sand and buckwheat were selected as the food particles, the size of which was classified into three grades. The effect of the size and hardness of food particles on the three-body wear of human enamel was investigated under ball-on-flat contact using a reciprocating apparatus. The surface characteristics of samples were examined by micro-hardness tester, optical microscopy (OM) and laser confocal scanning microscope (LCSM). Main conclusions are drawn as follows:1. When the sand particles act as third body, the stable value of friction coefficient decreases a little with the decrease in the size of the particles, and the morphologies of the enamel worn surfaces transform from delamination to ploughing. In addition, When the buckwheat particles act as third body, the stable friction coefficient decreases remarkably with the decrease in the size of the particles, meanwhile, the morphologies of the enamel worn surfaces transformed from ploughing to slight scratch.2. When the size of food particles is similar, the stable friction coefficient is higher under the condition of hard particles than that under the condition of soft particles, which is more and more significant with the size of food particles decreasing. The worn surfaces of enamel are characterized mainly by delamination and ploughing under the condition of hard particles, while slight scratch is dominant on the worn surfaces of enamel under the condition of soft particles.3. Compared with the two-body wear of enamel, the food particles with low hardness and small size may act as solid lubricant and alleviate the three-body wear of enamel, however, the food particles with high hardness and large size could aggravate the three-body wear of enamel.