1, front teeth: located in the front of the mouth, with S * * * up, down, left and right. Its * * * feature is that the crown is shovel-shaped from the lip surface, wedge-shaped from the adjacent surface, the neck is thickest, and it gradually becomes thinner towards the cutting edge, becoming a full ridge. The front teeth are single.
2, fangs: located near the corners of the mouth, there are four * * * supporting lips on the top, bottom, left and right to make them plump. Its characteristic is that the crown is conical, and the center of the cutting edge has a prominent sharp point, which is single, long and straight, and is the largest root.
3, bicuspids: located behind the fangs, also known as premolars. There are 8 teeth on the upper, lower, left and right sides, and there are two sharp points on the occlusal surface (the bicuspid teeth on the lower collar sometimes have three sharp points). The crown is an irregular cube with a flat root, but the first bicuspid tooth on the upper collar usually has two roots.
4. Molar: located behind bicuspid teeth, with *** 12 upper, lower, left and right teeth. The crown is large and cuboid, and the occlusal surface of the upper teeth is irregular diamond, while the occlusal surface of the lower teeth is rectangular. There are usually 4-5 sharp points. Generally there are three upper molars and two lower molars.
Extended data
The structure of teeth is mainly composed of dentin, enamel, cementum and pulp. Dentin is dense and hard, which constitutes the main body of the tooth and is located inside the tooth. There is a layer of adhesive (cementum) outside the dentin at the root of the tooth, while the surface of the crown has white, bright and hard enamel. Enamel has the highest degree of calcification and is the hardest tissue in human body.
Crown cavity and root canal are collectively called dental cavity, which is filled with blood vessels, nerves, lymphatic vessels and connective tissue, and is called dental pulp. Lactobacillus in oral cavity can ferment sugar to produce acid, which leads to decalcification of enamel and tooth cavity, which is called dental caries clinically. If the cavity deepens and spreads to the nerve of the pulp, it will cause severe pain.
Baidu encyclopedia-tooth
Baidu encyclopedia-tooth