The purpose of this study was to determine how the mandibular growth pattern, maxilla and craniofacial pattern was effected by the forces translated to this area by chin cup. Both control and treatment groups were composed of 10 persons and were 9 years old. The subjects of treated sample were requiered to wear chip cup 18 hours per day. The total force delivered was 900 gr, 450 gr per side and the direction of force was on average through the condyle. Some patients wore removable posterior bite planes for the correction of cross-bite if necessary. The study was constructed on the first and second lateral cephalometric roentgenograms of individuals. The results of this study indicate that chin cup caused a closing of cranial flexure angle NS Ba..... Mandibule was positioned distally and gonial angle was decreased.

Keywords: Chin cup, Class III malocclusion, mandibular growth pattern