A study of mandibular shape.

The technique of medial axis transformation of the outline form was used for the specific analysis of mandibular shape. When used to compare mandibular shape derived from lateral cephalographs between three equal samples of 30 female patients aged 12-15 years, marked overall similarity was noted between patients with Classes I, II and III occlusions. There were however subtle contrasts including the degree of coronoid and condylar separation and orientation of the ramus relative to the corpus. Such constancy of mandibular form derived from this technique of investigation was marked contrast to the data of traditional cephalometric studies which combine both size and shape parameters together. This study therefore demonstrated that shape appears less variable than size.