According to the characteristics and functions of teeth, they can be divided into the following categories:
1. Incisors: located in the front of the mouth, there are a total of s up, down, left and right. The common feature is that the crown of the tooth is shovel-shaped when viewed from the lip surface and wedge-shaped when viewed from the adjacent surface. The tooth neck is the thickest, until the incisal edge gradually becomes thinner, becoming all ridges. The incisor is a single root.
2. Fangs: located near the corner of the mouth, there are 4 upper, lower, left and right fangs to support the lips to make them plump. It is characterized by the crown of the crown and the protruding tip at the center of the incisal margin. The root is a single root, long and straight, and the largest of the roots.
3. Bicuspid teeth: located behind the canines, also known as premolars. There are 8 top, bottom, left, and right cusps. There are two cusps on the occlusal surface (the lower collar bicuspid teeth sometimes have three cusps), the crown is an irregular cuboid, the root is flat, and it is a single root. A pair of canines usually has two roots.
4. Molar teeth: Behind the bicuspid teeth, there are 12 upper, lower, left and right teeth. The crown is large and cubic, the occlusal surface of the upper collar molar is irregular, and the occlusal surface of the lower collar molar is rectangular. Usually there are 4^-5 cusps. An upper collar molar generally has three roots, and a lower collar molar has two roots.