Changes in mandibular growth direction during and after cervical headgear treatment

Cervical headgear is widely used to modify sagittal growth in growing patie nts. However, cervical headgear can affect vertical growth as well. The pur pose of this retrospective cephalometric study was to examine mandibular gr owth 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 rad iographs for the control subjects. During the 4-year treatment or observati on period, the mean mandibular rotation was 0.25 degrees in the treatment g roup 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 tr eatment 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 differe nt between the 2 groups. Mandibular rotation during retention did not show any significant inverse correlation with mandibular rotation during treatme nt. These findings suggest that mandibular rotation during retention reflec ts the inherent growth pattern of an individual that is reasserted after tr eatment, 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 clinical ly significant bearing on mandibular rotation. Vertical changes in the maxi llary and mandibular molars showed no significant correlation with mandibul ar rotation, which suggests that the changes in vertical dimension of the d entition are not a major determinant of the rotational change of the mandib le.