An analysis of craniofacial form; the need for new analytic techniques.

This study was based on lateral cephalographs of 443 patients aged 7--18 years to determine the effects of age and occlusal (Angle) relationships on craniofacial form. From 33 datum points, 56 linear and angular dimensions were subjected to the multivariate statistical technique termed principal component analysis. This technique not only enabled a number of parameters to be combined together but also computed a series of orthogonal variates (components) accounting for over 90 percent of the total variance. The subsequent analysis of the component scores revealed marked contrasts in craniofacial form not only between age groups but also between different occlusal categories. The interpretation of such data remains controversial, since not only do traditional craniofacial parameters combine both size and shape together, but they are based upon datum points of unknown degrees of homology. This study therefore confirmed the complexity of craniofacial form and demonstrated the need to develop more appropriate analytic techniques with the specific objective of defining shape and shape change.