British and West African facial form in ideal occlusion

True lateral cephalometric radiographs of 20 adult male British subjects and 20 Nigerian adult males were collected. All subjects showed an ideal occlusion of the teeth. These radiographs were analysed using a facial polygon joining the points Nasion, Sella, Articulare, Gonion and Menton. Additionally, measurements were made of the axial inclination of the incisor teeth and the distances from the incisal edges and apices of the teeth to the facial plane. Statistical examination of the results using "t" tests revealed that the average British mandible had a longer ramus but shorter body joined at a wider angle than the Negro, that the nasal part of the face was longer on average in the British group and that the incisor teeth, on average, projected further and were inclined further forward in the Nigerian group. A linear discriminant function in only three variables predicted with 100 per cent accuracy membership of the two groups. The three variables were the mandibular body length, the height of the nasal part of the face, and the amount by which the incisal edges of the lower incisor teeth projected beyond the facial plane.