Normal people's teeth are divided into four areas: upper, lower, left and right. According to the shape and function of teeth, they are divided into incisors, canines, bicuspids (premolars) and molars, with *** 16 pairs. Paired left and right, paired up and down. Cutting teeth:
They are mainly distributed in upper, lower, left and right pairs, with a total of 8 teeth, namely, maxillary central incisors, maxillary lateral incisors, mandibular central incisors and mandibular lateral incisors as shown below. The main function is to cut food, which will also affect our pronunciation and the beauty of our face. The best state is that the size, shape and position are in harmony with the face, mouth and lips.
Fangs: Located in the far middle corner of the lateral incisors, there are four fangs, namely upper fangs and lower fangs. The main function is to tear food.
Bicuspid: Also known as premolar, there are eight teeth on the upper, lower, left and right sides, which are located at the distal end of the canine and the proximal end of the first permanent molar, and mainly assist in tearing and mashing food.
Molar: There are three molars, one *** 12, which is located in the far middle of bicuspid teeth. Molar teeth are the most important functional teeth in the oral cavity. Premature defect of molars can easily lead to decreased masticatory function, even affect temporomandibular joint, resulting in abnormal facial development and occlusal pain. Take on the main chewing task and grind food. If you have problems with your molars, you must seek medical advice in time.
From the longitudinal section of the tooth, we can see that there are three layers of hard tissue and one layer of soft tissue, namely enamel, dentin, cementum and gum. Enamel:
Generally covering the surface of teeth, it is the hardest part of tooth tissue and has a high degree of calcification. It is translucent and milky white, and the color change is related to the calcification degree of enamel.
Cementum: It mainly covers the surface of gums, and its hardness is similar to that of bones. It is thinner at the neck of the tooth, thicker at the bifurcation of the root tip and molar root, and the color is light yellow.
Dentin: located in the inner layer of enamel and dentin, it is the main body of teeth, with light yellow color and lower hardness than enamel, but higher than bone.
Dental pulp: loose connective tissue located in the pulp cavity, mainly blood vessels, nerves and lymphatic vessels, surrounded by hard dentin.
Tooth body is generally composed of crown, neck and root. Crown:
It is the covering part of the teeth exposed in the mouth, and the outer layer is enamel. Its main function is to chew food.
Root: the part of the tooth below the neck and buried in the alveolar bone, and it is also the main supporting part of the tooth. The shape and number change with the function and change of teeth. For example, tooth cutting is mainly used to cut food, so it is a single root; The main function of molars is chewing, and the roots are bifurcated into 2-3 roots to enhance stability.
Dental neck: located at the junction of crown and root, it is arc-shaped and called dental neck.