2003 – VOLUME 32 – Issue 3

The timing of orthodontic treatment should be judged by two criteria, effectiveness (how well it works) and efficiency (benefit relative to costs and risks). Ideally, treatment would be done at the time it is most effective and efficient. For most children, that time is during the adolescent growth spurt, in the late mixed dentition or early permanent dentition. Treatment after adolescence is indicated primarily when prolonged growth would lead to relapse. This occurs especially in mandibular prognathism and sometimes in anterior open bite. Early treatment, before the adolescent growth spurt, has been advocated recently to make arch expansion more successful, but there is no evidence to show that this produces better results than expansion at adolescence. Only if extreme crowding exists is there an indication for early (serial) extraction. Data from recent randomized clinical trials show clearly that early Class II treatment for most children is not more effective than later treatment at adolescence, and it is less efficient. Early Class II treatment, therefore, is indicated only for children with special problems. A primary indication for early treatment is maxillary deficiency, because the window of opportunity for orthopedic maxillary advancement closes at about age 8. Mandibular growth at adolescence, however, can negate the advantage of early maxillary advancement, so it is important to distinguish between Class III problems due to maxillary deficiency from mandibular prognathism.