The most common time for orthodontic treatment is between 11 and 15 years of age, or just after all the permanent teeth have erupted. Sometimes treatment is necessary purely for esthetic reasons (crooked teeth, spaces, crooked smile), however, often times it is due to a malocclusion or severe crowding which can contribute to poor oral health.
In most cases, it is important to treat children while they are still growing so we can influence the growth to create an optimal bite.