Mandibular growth consists of a periosteal growth of cortical bone and an endochondral growth of the condyle. Active mandibular growth occurs in the condyle. It has been suggested that mandibular morphology derived from periosteal growth is attributed to condylar growth. Bjork reported that ramus height is increased, mandibular body is curved and gonial angle is small in vertical condylar growth, whereas ramus height is short, mandibular body is little curved, and gonial angle is large in sagittal condylar growth. In the treatment of Class II malocclusion with a retrognathic mandible, it is possible that both of growth at the condyle and changes in mandibular morphology are related to improvements in sagittal jaw relationships. Therefore, to better understand the effects of functional appliances, it would be helpful to evaluate the effects on mandibular growth by separating growth at the condyle and change in mandibular morphology.
The objective of this presentation is to clarify the effects of activator treatment on mandibular growth in relation to condylar growth and mandibular total rotation by regional superimpositional measurements, and to investigate the relationships between treatment responses and pretreatment facial morphology.