Loss of root length and crestal bone height before and during treatment in adolescent and adult orthodontic patients.

It is broadly documented that orthodontic tooth movement enhances the risk of apical root resorption and loss of alveolar crestal bone height, but virtually all studies have focused on the conventional adolescent patient. In this study, samples from adolescent and adult patients were matched for sex, malocclusion, and treatment regimen. In-treatment changes in root length were the same for both groups, whereas loss of crestal bone height was somewhat greater in adults. Major differences, however, were found at the start of treatment: Adults (mean = 28 years) had significantly shorter roots and greater alveolar recession than the young teenagers (mean = 12 years). Consequently, treatment per se does not place adults at greater risk; it is the involvement extant at the start of mechanotherapy that merits careful evaluation.