The ancients pursued "eyes like pearls, teeth like shells", but now people care about "beauty, bright eyes and white teeth", which is an obstacle to people's gradual beauty. It is a common problem in the field of stomatology, and the incidence rate in the population is as high as 80%~90%. China people belong to Mongolian race, most of them are convex, and the total number of teeth is relatively large relative to the amount of jaws. With the development of mankind, the fineness of food is getting higher and higher, the intensity of mandibular stimulation is getting lower and lower, and the incidence of malocclusion is getting higher and higher. Tooth deformity will not only affect the normal chewing function to varying degrees, but also affect the normal development of maxillofacial region, thus affecting the beauty of the whole face; Tooth and jaw deformities, such as uneven tooth arrangement and crowded dislocation, have poor self-cleaning effect on teeth and unsatisfactory brushing effect. Food residues and dental plaque are not easy to remove to form soft scales and dental calculus, and they are prone to dental caries and gingivitis over time, which can develop into periodontal disease seriously, causing teeth to loosen and fall off; For example, irregular teeth, open lips to expose teeth, facial disharmony caused by maxillary protrusion, mandibular protrusion, mandibular retraction, long face shape and short face shape will all affect the beauty of face shape. If children's dentofacial deformities cannot be corrected in time and early, it will affect the development of soft and hard tissues in the oral cavity and face, resulting in obvious facial deformities, such as protruding teeth, protruding face, tiled face and asymmetrical face, which will affect the overall image of patients and have a negative impact on their future study, life, job selection and social interaction. It has a great influence on the physical and mental health of patients (see Zhong Jia's blog post-Types of malocclusion and what are the hazards of malocclusion? ), so that these children have inferiority complex when interacting with others, leading to psychological barriers. The sooner you do orthodontics, the better. However, it is understandable that patients and their parents who need orthodontic treatment will stop when they hear that orthodontics needs to remove one or even several healthy teeth, and they are worried that their children's face will sag after tooth extraction, and their chewing function will be affected, and that other teeth in their mouths will loosen and shift after tooth extraction (see the blog post of Zhong Jia Tooth Xi-What are the adverse effects of orthodontic treatment). -Orthodontic sequelae). But you can't give up treatment because you don't want to pull out your teeth and miss the best age for treatment. To correct the malocclusion of teeth, it is often necessary to provide enough clearance by extracting teeth, so as to arrange the teeth and establish a harmonious shape and proper functional relationship. Especially when the dentition is crowded, the number of teeth and the number of bones are not harmonious. Only extraction can arrange teeth, establish a good occlusal relationship, improve dental arch protrusion, correct molar relationship, and improve the coordination between upper and lower dental arches and between jaw and craniofacial area. Mild crowding (the degree of crowding is 2~4 mm), and the limited gap can be obtained by expanding the dental arch; Moderate crowding (the degree of crowding is 5~9 mm), most of them should be treated with tooth extraction. Of course, not all orthodontic patients need to have their teeth extracted. When correcting dentofacial deformities, some patients really need to have their teeth extracted to obtain satisfactory treatment results. Will they receive treatment? Do it or not? You need to weigh the pros and cons yourself. After all, you make your own decisions. So why do some patients need tooth extraction treatment? In the design of orthodontic treatment, some patients need orthodontic treatment after tooth extraction. Tooth extraction is a necessary step to treat some malocclusion. As for the disharmony between the amount of teeth and bone, and the disharmony of jaw position, only tooth extraction can make the patient's jaw, jaw and face establish a coordinated shape and a suitable functional relationship, and maintain a stable effect. 1. Relieve the crowding and make room for tooth arrangement: when the teeth are unevenly arranged, there will be severe crowding or close to severe crowding (the degree of crowding is greater than 10 mm). If you want to arrange the teeth, meet the aesthetic requirements and ensure the stability of the effect after orthodontic treatment, you should extract the teeth as needed. Use the gap between tooth extraction to relieve crowding, make the crowded teeth in order, coordinate the tooth quantity and bone quantity, make the teeth in order on the dental arch, and establish a good occlusal relationship; Patients with crowding degree II-III are more likely to have their teeth extracted. If the teeth are not extracted and the dentition is barely arranged, the orthodontic effect will be unstable and it will easily relapse into the original crowded malocclusion. 2. Improve the protruding face shape by extracting teeth and adduction: When the teeth are arranged neatly and there is no crowding phenomenon, such as maxillary protrusion and bimaxillary protrusion, if you want to correct the protruding deformity, you need to extract teeth to correct it. Retract the front teeth by using the extraction gap to improve the protrusion of dental arch and correct the molar relationship, so as to correct the disharmony between the upper and lower dental arches and between the jaw and the occlusal surface, thus improving the protrusion of dental arch and correcting the protruding facial shape. For example, some people's lips are protruding, and the protruding amount of lips will become smaller after tooth extraction correction, and the face shape will become softer and more beautiful (for details, please refer to Zhong Jiaya Xi's blog post-Orthodontic Methods). 3. Use tooth extraction to coordinate the relationship between upper and lower dental arches. The occlusal relationship of the posterior teeth is adjusted by the extraction interval, so that the posterior teeth are staggered, the maximum occlusal contact area is achieved, and the best chewing efficiency is formed. In the case of vertical disharmony of dental arch (opening and closing of anterior teeth, deep overbite), uneven width of dental arch (locked occlusion of posterior teeth, asymmetric molar relationship, midline deviation), and uneven tooth quantity of upper and lower dental arch (congenital missing teeth), orthodontic treatment of tooth extraction can be considered. What are the factors that determine orthodontic tooth extraction? Orthodontic tooth extraction treatment is generally harmless. Usually, doctors prefer to choose the diseased teeth in the mouth or the teeth that have the least influence on chewing function, and generally will not cause the decline of chewing function. Moreover, orthodontics can also improve the original teeth with poor chewing function, which not only enhances the function, but also improves the appearance. As for whether or not to pull out teeth, how many teeth to pull out and which teeth to pull out, the doctor should accurately measure the tooth crowding, Spee curve height, dental arch protrusion, bone surface shape, the estimation of anchorage molar deviation and the outline of soft tissue according to clinical examination, X-ray examination and model analysis. In order to ensure the coordination of the upper and lower teeth and the symmetry of the left and right sides, it is common to pull out four bicuspids in the upper, lower, left and right mandibles. At the end of orthodontic treatment, the tooth extraction gap will be accurately closed by the orthodontist, so patients and parents don't have to worry. After orthodontic treatment, the function and health of teeth will not be affected. About 50%~60% of orthodontic patients in China need tooth extraction. The method of tooth extraction in orthodontic treatment: 1. For most cases that must be extracted, the first pair of fangs is the most commonly extracted tooth. The teeth are located behind the canine teeth, at the junction of the front teeth and the rear teeth. The extracted gap can be easily used by the crowded or protruding front teeth, and its shape is similar to that of the second bicuspid teeth. After the gap is closed, the canine and the second bicuspid can have a good abutment relationship. Generally speaking, the extraction of bicuspids has little effect on the shape and function of dental arch. Secondly, in order to maintain the left-right symmetry of the corrected tooth arrangement and ensure that the midline of the tooth does not deviate, the left and right sides are usually removed at the same time; Similarly, in order to establish a good occlusal relationship between upper and lower teeth after correction, upper and lower dental arches are usually used to extract teeth at the same time; In this way, the most commonly used tooth extraction treatment scheme is to extract the first pair of fangs up, down, left and right respectively; Of course, some patients may also adopt other tooth extraction schemes, and then decide after specific diagnosis and analysis. 1. Pull out two mandibular first premolars and two maxillary second premolars. If the patient's back teeth tend to be completely close to the middle, but the upper teeth are not very crowded, this extraction mode can be considered. By extracting the maxillary second premolar, more maxillary first molars can be moved forward. To promote the establishment of class I occlusal relationship between maxillary and mandibular first molars. This tooth extraction mode is mainly suitable for patients with skeletal type I and mild type III. During the proximal movement of the maxillary first molar, attention should be paid to prevent the midplane collapse caused by excessive lingual movement of the upper anterior teeth. 2. The molar relationship of the patients who extracted four first premolars is near-middle-tip-to-tip or neutral occlusion, and the upper anterior teeth are severely crowded, and the lower anterior teeth are accompanied by severe crowding or protrusion. Consider this extraction mode. A large part of the maxillary extraction space is used to relieve the crowding of anterior teeth, a small part is used to close the posterior teeth, and the mandibular extraction space is mainly used to relieve the crowding and protrusion of lower anterior teeth. The lower posterior teeth should not move forward as far as possible, and finally the class ⅱ occlusal relationship between the left and right first molars and the normal overbite relationship of the anterior teeth should be established. This tooth extraction mode is mainly suitable for V-type patients. 3. When the maxillary dental arch is basically normal or slightly crowded when the mandibular first premolar is extracted, it can be relieved by lip expansion or a small amount of arch expansion of the anterior teeth. In order to make the postoperative appearance beautiful and harmonious, only the method of extracting the mandibular first premolar can be chosen. At the end of the treatment, the relationship between the upper and lower first molars of the patient was completely Class III, and the relationship between canine teeth was Class I. The problem of mandibular overgrowth was corrected by retracting the anterior teeth. The advantage of this model is that two maxillary premolars are removed less, which reduces the fear and pain caused by excessive tooth extraction. At the same time, it is helpful to keep the maxillary dental arch and soft tissue full, and the postoperative aesthetic effect is good. The only fly in the ointment is that the relationship between maxillary and mandibular molars can only maintain class III relationship. Although this relationship is not an ideal occlusal relationship, it is still an ideal tooth extraction treatment as long as the occlusal function is good, which is usually chosen by patients with bone type ⅲ. 4. Pull out two mandibular second molars. Early extraction of the mandibular second molar, moving the first molar away to make it neutral with the maxilla, the mandibular third molar will adjust itself to the middle to replace the second molar. The advantage of this tooth extraction mode is that both molars and canines meet the standard class I occlusion relationship, but the disadvantage is that sometimes some patients' mandibular third molars are not ideal in self-adjustment and need orthodontic assistance, so the correction cycle will be appropriately extended, and the cost and time will increase accordingly. 5. In some patients, the relationship between the lower central incisors and the posterior teeth is completely Class III malocclusion, and the disharmony between the upper and lower teeth leads to mild malocclusion or opposite occlusion of the anterior teeth. After Bolton index analysis, this kind of patients can choose the extraction method of lower central incisors after confirming that the extraction of lower central incisors can make the Bolton index close to or reach the normal range. After operation, the maxillary and mandibular first molars were kept completely close to each other, and the normal overlapping relationship of anterior teeth was established. The disadvantage of this model is that it sacrifices the midline relationship of mandibular incisors and cannot be consistent with the midline of maxillary incisors. Matters needing attention in orthodontic treatment: Orthodontic treatment is a long-term and slow process, patients need a good attitude, doctors need your good cooperation and regular follow-up visits. Before each review of orthodontic force, orthodontists will make a preliminary assessment of the direction and degree of tooth movement. However, due to individual differences, the alveolar bone of each patient reacts differently to orthodontic force, and the actual situation of tooth movement is also different from the estimated situation. Therefore, it is necessary to follow up the patients on schedule, so that doctors can grasp the patient's situation and the progress of denture movement in time. At the same time, regular follow-up visits can also make you accept sustained and stable orthodontic force, which is beneficial to the continuous movement of teeth, the gradual reconstruction of alveolar bone and the maintenance of orthodontic effect.