Biphasic orthodontics is a concept that has been proposed for a long time, but is still not well understood by many patients and families. Here is a brief explanation. What we mean by malocclusion is not only a dental problem, but in many cases also a bone problem, such as a “small chin” or a “grounded skull”. These serious bony problems are often treated in two phases to achieve better orthodontic results for the right adolescent, i.e. the first phase to solve the bony problems (the best age is before the arrival of the growth hills, i.e. 9 to 11 years old for girls and 12 to 14 years old for boys), and the second phase to solve the dental problems. If the bony problems are not solved within the right time window, it will make orthodontics more difficult and some cases that do not need to be extracted will end up with tooth extraction as a substitute treatment, or in serious cases, surgery may be the only option. Due to the nutrition of children nowadays, the development of many children has advanced, and the above-mentioned optimal age for the first phase of orthodontic treatment is not always accurate, so if parents feel that their children have bone deformity problems, it is best to find a specialist to consult, so as not to miss the best time for treatment and leave regrets.