Lower cranial height vs craniofacial dimensions in Angle Class II malocclusion

From the serial sample of the Burlington Growth Centre, 68 children with Angle Class II malocclusion were contrasted with 148 children with Class I occlusion. Body height, cranial height, cranial base flexure and jaw position relative to the cranium were compared at ages 8, 12 and 16 years. In the Class II groups, the cranial base angle was significantly (P less than .05) larger, upper cranial height was slightly larger, lower cranial height was slightly smaller, the maxilla was slightly more posterior to Sella, and the mandible was significantly more posterior. Between ages 8 and 16 years, lower cranial height increased and cranial base angle decreased, with a strong negative correlation. Lower cranial height and the anterior position of the maxilla and mandible from Sella correlated significantly (P less than .01) with body height in Class I children, but in Class II only in boys 8 and 12 years of age. This lower correlation in Class II children was accounted for by those with a moderate to tall stature but disproportionately small lower cranial height. In Class II children the jaws, especially the mandible, had a more posterior position under the cranium, and there was a more open flexure of the cranial base and shorter lower cranial height. Correlation of stature with lower cranial height and with the anterior position of the jaws relative to the cranium was much lower in Class II children, especially in girls.