There are many reasons for irregular teeth: First, if the milk teeth are seriously decayed, in the process of milk teeth falling off and permanent teeth erupting, it is easy to have irregular permanent teeth, this is the most common reason. Second, if the child has the habit of licking the teeth, often use the tongue against the teeth, it is easy to cause the teeth misalignment. Third, if there is trauma, such as milk teeth, just erupted permanent teeth, encounter external factors, easy to cause the phenomenon of malocclusion. If the teeth are not aligned, it not only affects the beauty, but also affects the good bite relationship, you can go to the orthodontic department of the hospital to do orthodontic treatment to restore the alignment of the teeth, the best age for treatment is around 12-13 years old.