Intuitively, the number of teeth that each person can hold in his mouth is limited. We call the sum of oral bone mass and the width of all teeth as tooth quality. According to the relationship between bone mass and tooth mass, the following three situations appear:
1, bone and teeth are equal, which is the most ideal, because the two match, most of them do not need correction, or just need simple alignment;
2. The bone mass is less than the tooth mass. This is the most common situation, that is, the total number of existing teeth can not be accommodated in the mouth, which is characterized by irregular teeth and oblique displacement. Generally speaking, the congestion below 4 mm can be corrected without tooth extraction, and the congestion above 4 mm can be corrected by tooth extraction. The specific location and number of tooth extraction need to be determined after measurement and analysis;
3, the bone mass is greater than the tooth mass, indicating that the teeth have cracks. In this case, tooth extraction is not necessary. The backlash can be used to adducte protruding teeth, or the teeth can be moved forward to close the backlash.
Patients with crowded dentition can only arrange their teeth by expanding the arch if they don't extract teeth, but the stability of the dentition after expanding the arch is not good, so they need to wear retainers for a long time. After tooth extraction, the gaps are all closed, the tooth arrangement is relatively stable, and the protruding teeth can be retracted to improve the facial appearance. Parents and friends don't have to worry about eating, they are arranged neatly, and the chewing efficiency is greatly improved compared with that before correction, and will not be affected by the reduction of the number of teeth.