Dentofacial orthopedics in relation to somatic maturation. An analysis of 70 consecutive cases treated with the Herbst appliance.

Mandibular treatment changes were related to somatic maturation in 70 consecutive cases of Class II malocclusion (52 boys and 18 girls, aged 10 to 16 years) treated with the Herbst appliance for an average period of 7 months. Sagittal and vertical alterations in mandibular condylar growth and sagittal changes in molar and incisor tooth position were analyzed by means of mouth-open profile roentgenograms. The somatic maturity level of the patients was assessed by means of longitudinal growth records of standing height. The treatment period was related to the peak height velocity by dividing the patients into three growth-period groups: prepeak, peak, and postpeak. Herbst treatment resulted in Class I dental arch relationships in all patients. Post-Herbst treatment changes were not evaluated in this study. Sagittal condylar growth was increased and the mandibular molars and incisors were moved anteriorly. When the mandibular skeletal and dental changes were related to the subjects' somatic maturation, significant differences between the different growth periods existed in boys and tendencies were noted in girls as follows: sagittal condylar growth was most pronounced in the peak period, anterior molar movement was equally large in all growth periods, and anterior incisor movement was most extensive in the postpeak period. To take advantage of the increase in condylar growth response and to reduce the time of posttreatment retention, it is suggested that Herbst therapy be instituted close to peak height velocity.