The variability of some craniofacial dimensions.

The variability of eight linear and five angular dimensions measured on 124 lateral skull radiographs of 10-year-old boys was assessed by means of Bartlett's test for homogeneity of variances and Pitman's test for the comparison of correlated standard deviations. The linear dimensions which demonstrated the greatest variability within the four constituent Angle classes (N = 31) were mandibular body length, total cranial base length, total mandibular length and lower face height. The dimensions which demonstrated the least intra-group but greatest inter-group variability were maxillary length and Angle SNB. The Class II division 2 group exhibited the greatest variation in skeletal morphology; it is therefore postulated that its etiology is mainly dentoalveolar and soft tissue in origin.