AVERAGE AFRICAN-AMERICAN 3-DIMENSIONAL COMPUTED-TOMOGRAPHY SKULL IMAGES - THE POTENTIAL CLINICAL IMPORTANCE OF ETHNICITY AND SEX

The production of average 'normative' three-dimensional (3D) computed tomography surface images of the bony skull has only recently been exp lored. The authors wish to determine the effect of using sex- and ethn icity-specific adult average 3D skull images for comparisons with pati ent images at various stages of craniofacial surgical management (i.e. , diagnosis, treatment planning, prosthetic design, image-guided opera tive procedures, and outcomes assessment). Craniofacial surgical recon struction for abnormal patterns of development, cancer resection, or t rauma are most likely to benefit from these comparisons. To morphometr ically test the significance of separating normative 3D skull data by sex: and ethnicity, the authors collected 52 3D, anatomical landmarks from 3D computed tomography scans of dry skulls of 20 Americans of Eur opean ethnicity and 20 Americans of primarily African (i.e., primarily African and some European) ethnicity. A Procrustes-based morphometric analysis of shape detects 1.2 times as much interethnic variance as i ntersex variance. The African American sample presents 4.2% more dolic hocephaly, wider orbits, flatter nasal area, larger gnathic anatomy, a nd more procumbent dentition. Pooling the sexes across both groups, it is seen that men tend to have less bulbous crania, more protruding br ews, noses, and masticatory muscle attachments, and relatively less pr otrusive palettes and anterior mandibles. Despite a small sample size (N = 40), the authors' results are statistically significant (P simila r to 0.001 overall) for both of the main factors, sex and ethnicity, s eparately.