Malocclusion is most likely caused by misalignment of teeth or malformation of jaw development, because only the lower jaw is movable in the head and face, and is normally symmetrical to the left and right. If the malocclusion or deviated jaw occurs due to congenital genetic factors or acquired trauma, as well as problems during the construction of the teeth, it is important to go to the hospital as soon as possible when it is discovered, otherwise it will easily cause TMJ disorder afterwards. In case of malocclusion, the best age for treatment is after 3 weeks of age and before 12 years of age, when skeletal development is still in progress, once the age of 12 years is exceeded, it is difficult to correct the skeletal deformity if the best age is missed. If the malocclusion is only caused by misalignment of teeth, treatment can be started at the age of 12 years. Parents must pay attention to the many dangers of malocclusion.