Clinically, we judge the starting point of orthodontic treatment for children based on the order of tooth eruption and the developmental status of tooth arrangement, in order to grasp the best time for orthodontic treatment. The period of baby teeth Generally speaking, from 6.5 months to 2.5 years old, the 20 baby teeth will be erupted in order, and all teeth in the mouth are baby teeth until 6 years old. This is also known as the “teething stage”. At this time, parents need to pay attention to their children’s oral hygiene and prevent tooth decay, and try to keep the dental arch intact to avoid the lack of space caused by early tooth loss. This is also called the “preventive orthodontic period”, when orthodontic treatment is not usually performed because of the child’s young age and low level of cooperation. However, if your baby has any of the following conditions, the first orthodontic examination should be done immediately after the eruption of 4 incisors in the upper jaw: 1) retrusion (i.e. enameled teeth); 2) bony protrusion (i.e. skeletal protrusion). The mixed dentition period From 6 to 12 years old, the baby teeth gradually fall off and the permanent teeth start to erupt one after another, which is the so-called “mixed dentition period”. During this period, parents are often worried about the alignment of their children’s teeth at this stage: they are worried that their new permanent teeth will be skewed and that their children will become ugly ducklings if they are not careful. During this period, parents should cooperate with the orthodontist for some early diagnosis and local treatment. Depending on the patient’s condition, the orthodontist will do some oral examinations, such as taking impressions and taking full-mouth and lateral cranial X-rays, in order to have a thorough understanding of the situation, prevent the occurrence of malocclusion, slow down the deterioration of the problem, and determine the best time for orthodontic treatment. If necessary, functional orthodontic appliances will be used for skeletal correction to improve jaw bone growth discrepancies. Permanent Period After the age of 12, all permanent teeth erupt and enter the “permanent period”, which is commonly referred to as the “puberty period”. During this period, children will experience significant growth in height and weight, including, of course, the development of the facial bones. According to studies, about 60-70% of patients begin orthodontic treatment between the ages of 10 and 12 (6th grade to 1st grade) because this is the time when tooth replacement (replacement of baby teeth with permanent teeth) is almost complete. By taking advantage of the time before the tooth replacement is completed and the softness of the alveolar bone during the tooth replacement period, the permanent teeth are induced into the dental arch by orthodontic treatment, which can reduce the pain during treatment and make the tooth alignment and bite more stable after treatment. In short, “early diagnosis and timely treatment” is the best principle of orthodontics. Therefore, if parents suspect that their children may have problems such as malocclusion, enameled teeth, bruxism, etc., they can bring their children to the doctor for diagnosis as early as possible so as to achieve the best treatment effect in the shortest possible time.