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 m andibular anterior alignment in a large group of Class II, Division 1, patients who demonstrated successful occlusal results at the end of a ctive treatment. The specific aim was to search for predictors of rela pse and associations between relapse and other postretention changes. The sample of 78 adolescents was limited to successfully treated cases as judged by subjective evaluation of intercuspation and incisor occl usion of posttreatment study models. Neither cephalometric characteris tics nor postretention occlusion were considered in sample selection. Of these patients, study models and cephalograms were available pretre atment, at the end of active treatment, and a mean of 14 years postret ention. The results demonstrated an increase of incisor irregularity a nd a reduction of intercanine width and arch length postretention. At postretention, 9.0% had Irregularity Index values of 6.5 mm or more an d 47.4% had values equal to 3.5 mm or less. Stepwise backward multiple regression analyses revealed that narrow pretreatment intercanine wid th and high pretreatment incisor irregularity were significant predict ors of relapse. Treatment increase of intercanine width and postretent ion decrease of intercanine width and arch length were associated with relapse.