Close to 30% of all orthodontic patients in the United States are adults. Despite this growing trend towards adult orthodontics, it pays to start orthodontic treatment early for maximum effectiveness. The American Dental Association recommends that children receive an orthodontic evaluation by age seven. Orthodontics is a specialty of dentistry that is concerned with the study and treatment of malocclusions (improper bites), which may be a result of tooth irregularity, disproportionate jaw relationships, or both. Orthodontic treatment can focus on dental displacement only, or can deal with the control and modification of facial growth. In the latter case it is better defined as "dentofacial orthopedics".