A Cephalometric Study of the Mesio-Distal Axial Inclinations of the Teeth

Abstract

Eighteen adult human skulls with "normal occlusion" were examined with oriented lateral, 15, 25, 45, 75, and 90 degree cephalograms from which the mesio-distal axial inclinations of the teeth were measured. This study indicates that a large variation of the mesio-distal axial inclinations of the teeth may occur and still have a "normal occlusion". The standard deviations varied from a maximum of 11.0 degrees for the maxillary third molar to a minimum of 3.4 degrees for the maxillary cuspid. Rotation of the midsagittal plane of the head with the film effected the measurements of the maxillary first molars and cuspids, and the mandibular bicuspids by producing divergence of their roots on the film image. No relationship was found between measurements of this sample and measurements of mandibular plane, A-B plane, Y-axis, facial angle, angle of convexity, Down's occlusal plane, lower incisor - A-Pg, and interincisal angle. A positive relationship was found between the measurements of this sample and the posterior one-half of nasal floor, posterior occlusal plane, and the labiolingual axial inclination of the lower incisor.