Changes in mandibular growth direction during and after cervical headgear treatment.

Cervical headgear is widely used to modify sagittal growth in growing patients. However, cervical headgear can affect vertical growth as well. The purpose of this retrospective cephalometric study was to examine mandibular growth changes in 30 growing Class II patients treated with cervical headgear and full edgewise appliances and to compare those changes with the changes occurring in 26 untreated controls. Cephalometric data were obtained from lateral cephalometric radiographs representing pretreatment, posttreatment, and postretention for each patient and from chronologically comparable radiographs for the control subjects. During the 4-year treatment or observation period, the mean mandibular rotation was 0.25 degrees in the treatment group and -1.7 degrees in the control group. After an average posttreatment period of 6 years 5 months, the mandible had rotated -1.5 degrees in the treatment group and -0.7 degrees in the control group. Mean changes in the y-axis angle and the mandibular plane angle during retention were not different between the 2 groups. Mandibular rotation during retention did not show any significant inverse correlation with mandibular rotation during treatment. These findings suggest that mandibular rotation during retention reflects the inherent growth pattern of an individual that is reasserted after treatment, rather than rebound. There were no significant differences in the size of the mandible between the 2 groups during the study period. None of the variables reflecting pretreatment morphology of the face had a clinically significant bearing on mandibular rotation. Vertical changes in the maxillary and mandibular molars showed no significant correlation with mandibular rotation, which suggests that the changes in vertical dimension of the dentition are not a major determinant of the rotational change of the mandible.