Occlusal stability after extraction orthodontic therapy in adult and adolescent patients.

In this study we compared the posttreatment stability of occlusion in adults and adolescents treated for crowding or maxillary protrusion with four-premolar extractions and edgewise mechanics at an average of more than 4 years out of treatment. The adolescent sample showed a significantly greater posttreatment increase in mandibular anterior crowding than the adult sample. Posttreatment overjet and overbite remained more stable in the adolescents. We noted a correlation between in-treatment expansion and posttreatment narrowing of mandibular intercanine width in the adults. Differences in postorthodontic occlusal changes were noted between the adult and adolescent samples.