A DETERMINATION OF CEPHALOMETRIC NORMS FOR NEGRO RACE

This study was designed to determine a mean and range of normal for each lateral cephalometric measurement in the American Negro. Statistical analyses were performed, comparing the measurements of the American Negro to accepted means in the Caucasian to determine significant differences between the two races. Lateral cephalometric radiograms of forty American Negro patients with clinically acceptable occlusion and Angle Class I molar relation were obtained. Standard tracings were performed, and fourteen measurements were made. These measurements were then compared with the norms of forty Southern Caucasian children taken from a study performed at the University of Alabama. The Tweed triangle (MPA-IMPA-FMIA) was significantly different in the Negro sample (P < .001). The mandibular plane was steeper, and lower incisors were more procumbent. Both incisors (1-NA; 1-NB) were shown to be more procumbent in relation to their bony base (P < .001). The mandibular location in relation to the anterior cranial base (SNB) was not significantly different (P > .2). In the Negro sample the maxilla was significantly anterior to the mandible (ANB) (P < .001) and the mandible in relation to the anterior cranial base (SN-GoGn) was steeper (P < .001). The maxilla (SNA) in relation to the anterior cranial base was positioned more anteriorly in the Negro sample (P < .001). The primary difference seems to be the bimaxillary dental protrusion, the steep mandibular plane, and the anterior placement of the maxilla in the American Negro population. © 1968.