Effect Of The Hardness Of Abrasive On The Microwear Of Human Enamel

Enamel is the most highly mineralized biological tissue. It is the hardest material in human body which locates in the outermost layer of the crown of a tooth. It is made up of a small amount of organic matter and water as well as content as high as 96-97% of inorganic. The main ingredient of inorganic is hydroxyapatite crystallites, which are glued together by proteins. Enamel acts as a function to protect the underlying soft dentin and pulp from mechanical destruction and chemical attacks. Enamel has a complex hierarchical structure. Dental friction and wear is inevitable in daily chewing process. The hardness of food and the surrounding liquid environment show an strong effect on wear of enamel. Knowledge of the wear mechanism of human tooth enamel under different conditions not only help us understand the tribological behavior of tooth enamel, but also provide useful suggestions for dental clinical treatment and development of bionic dental restorative materials.In this paper, the wear of human tooth enamel by abrasive particles with different hardness was studied by a multipiont contact nano-fabrication apparatus under similar contact pressure. By analyzing wear topography and debris on enamel surface, the wear mechanism between enamel and the abrasive particles was observed. The mechanic properties of human tooth enamel are affected by the surrounding environment. The micro-tribology performance of tooth enamel after water soaking was investigated by using a nano-indentation/scratch tester and atomic force microscope (AFM). In addition, this paper also made a preliminary study on the micro-wear mechanism of enamel under different loads, and estimate the critical load of enamel crystallites refinement. The main conclusions of the research can be summarized as follows:1、The effect of the abrasive hardness on microscopic wear mechanism of the tooth enamel was investigated. It was found that the abrasives with different hardness can wear the enamel surface under a certain condition. The higher hardness of the abrasives, the more serious.2、The effect of the mechanical properties of enamel surface soaking in water on microscopic wear was studied. Water soaking treatment can form a thin softened layer on the enamel surface. The longer the soak time, the lower hardness of soften layer, the more serious the scratch damage.3、The microscopic wear mechanism of tooth enamel was preliminarily revealed. At the micro scale, enamel wear mainly manifests as plastic deformation, material removal and grain refinement. Meanwhile, enamel particles can be refined at a critical contact pressure between 1.63 GPa and 1.71 GPa.