Long-term stability of mandibular incisors following successful treatment of Class II, Division 1, malocclusions.

The purpose of this study was to evaluate the long-term stability of mandibular anterior alignment in a large group of Class II, Division 1, patients who demonstrated successful occlusal results at the end of active treatment. The specific aim was to search for predictors of relapse and associations between relapse and other post-retention changes. The sample of 78 adolescents was limited to successfully treated cases as judged by subjective evaluation of intercuspation and incisor occlusion of posttreatment study models. Neither cephalometric characteristics nor post-retention occlusion were considered in sample selection. Of these patients, study models and cephalograms were available pretreatment, at the end of active treatment, and a mean of 14 years post-retention. The results demonstrated an increase of incisor irregularity and a reduction of intercanine width and arch length post-retention. At post-retention, 9.0% had irregularity index values of 6.5 mm or more and 47.4% had values equal to 3.5 mm or less. Stepwise backward multiple regression analyses revealed that narrow pretreatment intercanine width and high pretreatment incisor irregularity were significant predictors of relapse. Treatment increase of intercanine width and post-retention decrease of intercanine width and arch length were associated with relapse.