State of Art on Tribomechanical andTribo chemical Wear of Human Dental Enamel

The application of tribology in dentistry is one of the rapidly growing and expanding fields. Intensive research has been conducted to understand dental tribology for selection of artificial dental materials. In the current paper, an overview on tribomechanical and tribochemical wear, combined with a description of the different wear simulating equipment and devices which allows us to better understand the multifactorial nature of wear has been presented. Wear and tear of the dental enamel due to tribomechanical factors such as two-body abrasion and three-body abrasion has been emphasized. Dental erosion due to chemical effect and the effect of oral environments has also been considered. In addition to these, overview of wear modes and wear locations has also been covered. According to results obtained by the authors and from the literature, the main progress in the area of dental tribology on natural dental enamel is reviewed. Basically human teeth are mainly composed of enamel, dentine and pulp. Dental enamel is the hardest and most mineralized tissue in the human body. Enamel, consists of 92–96% of inorganic substances, 1–2% of organic materials, and 3–4% of water by weight. Human teeth act as a mechanical device during masticatory processes such as cutting, tearing, and grinding of food particles and food bolus. The tooth is the only mineralized organ that is located partially internal and partially external to the human body. From advanced materials science point of view, a tooth is a functionally graded composite material with mineralized matrix and organic reinforcements (Fig.1). It is composed of three basic structural parts, namely enamel, dentin and the dentin-enamel junction (DEJ). The anatomical crowns of teeth are covered by dental enamel. Enamel comprises a mineral phase and an organic matrix. Dental enamel has a unique microstructure consisting of aligned prisms or rods, which run approximately perpendicular from the DEJ towards the tooth surface. The interfacial area between rods is termed interred enamel which is protein-rich material. The DEJ can be considered as a biological interface between the external enamel and underlying dentin. It is a unique junction between highly mineralized tissues of different embryogenic origins, matrix composition and physical properties. Figure 1.Schematic sectional view of various parts of the teeth Tribology is the science of the mechanisms of wear, friction and lubrication of interacting surfaces which are in relative motion. Wear is defined as material removal whenever a surface is exposed to another surface or to chemically active substances, which can result in a progressive removal of material from surfaces through mechanical or chemical action. Wear of human Enamel