Selected cephalometric angular norms in Kikuyu children.

Fifty-six standardized lateral head radiographs of Kikuyu children, represented equally by sex and aged nine to 15 years, were evaluated to determine norms for six dentoskeletal angles. The mean values obtained for the measured variables in the two sexes were: SNA = 84.4 degrees (+/- 4.0 degrees); SNB = 79.3 degrees (+/- 4.1 degrees); ANB = +5.1 degrees (+/- 2.0 degrees); FMA = 34.0 degrees (+/- 5.1 degrees); IMPA = 96.2 degrees (+/- 5.0 degrees) and 1/1 = 111.6 degrees (+/- 7.7 degrees). Angle SNB was found to be significantly larger in females. A comparison of the means of the cephalometric angles for the Kikuyu children with those of black American children demonstrated a steeper Frankfort-mandibular plane angle and a more acute lower incisor to mandibular plane angle in Kikuyu children. The Kikuyu children were also noted to have a more prognathic maxilla relative to the cranial base and mandible, a greater inclination of the lower incisors to mandibular plane and a more acute interincisal angle when compared to white children. The study emphasizes the need for use of group specific norms for orthodontic diagnosis and treatment planning.