I. What is orthodontics? Orthodontics is the best way to treat various malocclusions, such as misalignment of teeth in different directions, torsion, narrow arch, crowded teeth, sparse teeth, abnormal tooth alignment, anticuspidity, maxillary protrusion, mandibular protrusion, bimaxillary protrusion, facial asymmetry, deep overbite of anterior teeth, insufficient height of lower 1/3 of the face, anterior open bite, etc. Malocclusion has a serious impact on the growth and development, facial appearance, bite function and psychology of the child. For adult patients who have missed the best treatment time for various reasons, modern orthodontic technology can also help them improve their facial appearance, restore normal bite function, promote oral health and restore self-confidence. Second, the appropriate time for orthodontics? Modern orthodontic technology allows people of any age to straighten their teeth. Although adults have passed the growth period, they can still be treated for malocclusion to improve their appearance, restore normal occlusal function and promote oral health. They can also provide space for dental implants and restorations. There is no age limit for adult orthodontic treatment. The oldest adult patient who has undergone orthodontic treatment in our hospital is 69 years old. In foreign countries, many elderly patients in their eighties are still orthodontically treated symptomatically. However, for very severe malocclusion (e.g., diastema), early orthodontic treatment (4-5 years old) is recommended. For children with malocclusion, there are three optimal ages for orthodontic treatment. 1. 4-5 years of age (the teething period). It is suitable for the treatment of malocclusion (diastema) and deep overbite (upper front milk teeth completely cover the lower front milk teeth), at this time, through simple early orthodontic treatment, to provide a favorable environment for the growth of the upper and lower jaws, to guide the jaws to grow in a normal direction, to correct bad habits, and to avoid or simplify orthodontic treatment in the permanent dentition. 2, girls: 8-10 years old, boys: 9-12 years old (period of tooth replacement). This period is suitable for the correction of functional malocclusion (caused by bad habits or occlusal interference) or bony malocclusion (caused by bad habits or genetics). For example, anterior malocclusion (diastema), severe jaw recession or hypoplasia, misalignment of the upper and lower dental arches, severe misalignment of individual teeth, eruption of permanent cuspids but the gap between the upper front teeth is still not closed, and various malocclusions caused by bad habits. Orthodontic treatment at this time can take advantage of the growth potential of the jawbone, promote or inhibit the growth of the jawbone, and provide the possibility of coordinated development of the upper and lower jawbone. Early breaking of bad habits allows the jaws and teeth to develop along a normal track. Correction of severe misalignment provides a favorable environment for normal eruption and replacement of the remaining teeth. Thus, the purpose of correcting misalignment and facial shape can be achieved. 3, girls: 11-14 years old, boys 13-16 years old, (early permanent teeth), at this time, the arch development has been basically completed, malocclusion stereotypes, a variety of malocclusion in this period can be actively orthodontic treatment, the use of jaw and facial jaw alveolar growth and development of the reconstruction, so as to achieve a more stable orthodontic effect. Third, is it necessary to extract teeth for orthodontic treatment? The need for tooth extraction is a combination of the following considerations: age, severity of malocclusion, degree of tooth crowding, jaw growth and development, facial shape, and an estimate of the child’s jaw growth and development in the next few years. After a comprehensive consideration, the doctor will make a careful decision whether to extract the tooth or not. In general, teeth are extracted because, relative to the jawbone, there is an excessive amount of teeth. Extraction is not terrible and will not lead to gaps between teeth at the end of orthodontics, let alone affect normal chewing function after orthodontics. Fourth, what kinds of orthodontic appliances are there? Commonly, there are fixed orthodontic appliances and movable orthodontic appliances. The movable orthodontic appliances are mostly used for individual teeth misalignment (e.g., antitussive) or upper and lower jaw misalignment caused by functional factors. More commonly used are fixed orthodontic appliances. Fixed orthodontic appliances can be divided into several major categories. 1, ordinary metal brackets aligners, the most widely used, practical, inexpensive, but has a certain impact on the aesthetics. 2, ordinary ceramic brackets aligners, similar to the color of the teeth, beautiful, but slightly higher cost. 3, self-locking metal brackets aligners, self-locking metal brackets can directly lock the orthodontic wire in the groove of the brackets, reducing the friction between the wire and brackets to improve the efficiency of orthodontic treatment, but the cost is higher than ordinary metal brackets. And ordinary metal brackets need ligature ring (wire) fixed orthodontic wire. 4, self-locking ceramic brackets aligners, low friction, foreign body sensation, high orthodontic efficiency, aesthetics, but the cost is higher 5, lingual aligners, bonded to the tongue, completely invisible. Tongue movement and pronunciation have a certain impact, the cost is high. 6, invisible braces, a series of transparent plastic braces, according to each patient personalized production. The orthodontic treatment is more limited, can only correct mild to moderate malocclusion, the cost is high. V. Will there be discomfort in the orthodontic process? During the orthodontic process, there will be mild loosening of teeth. It is normal to feel sore and swollen teeth after each follow-up visit with force, which lasts about 3-6 days. VI. How long does orthodontic treatment take? Simple orthodontic treatment for individual teeth during the milking and replacement period takes less time, about a few months. The more complex the malocclusion, the longer the orthognathic surgery and orthodontic treatment, the longer it takes. Tooth movement has its own rules, limited by physiological conditions, the speed of tooth movement can not be too fast, fast does not mean good. Otherwise, it affects the normal reconstruction of periodontal tissues, eventually destroying the teeth, periodontal health, the so-called “speed is not enough”, as if the high-speed rail also needs to control the speed. 7.When is combined orthognathic surgery and orthodontic treatment needed? For severe bony malocclusion such as bony bimaxillary protrusion, bony open bite, bony anterior bite, especially for adult patients, orthognathic surgery with preoperative orthodontic treatment and postoperative orthodontic treatment is the best choice.