Relationship of natural head position to craniofacial morphology

Abstract

This investigation aimed at discussing the utility of natural head position–based cephalometric variables and to evaluate the relationship between natural head position and craniofacial morphology. Lateral facial photographs and cephalograms of 284 young adult males taken in a natural head position were analyzed. The average inclination of the intracranial reference planes, Frankfurt horizontal, and palatal plane, in relation to the true horizontal were nearly similar and smaller than 1°. Variables based on the true vertical to describe mandibular sagittal position like B-N(vert) and Pg-N(vert) had very high variances. To study the topographic error, flexors and extenders were identified on basis of four positional variables: NSL/VER; FH/VER; PP/VER; and PMvert/VER. Only 15 measurements were different, according to at least 2 of the 4 positional variables. The 3 that were different in all categories were: facial axis (NBa/PmGn), lower face height (ANS-Me), and the facial ratio (N-ANS/ANS-Me). The “extenders” had higher values for the facial axis and lower face height, and smaller for the face height ratio. Besides these 3 measurements, there was a tendency for the extenders to have increased anterior vertical height, distal sagittal relations, and smaller and retrognathic mandibles. Correlation coefficients between postural and morphologic variables tended to confirm these observations. (Am J Orthod Dentofacial Orthop 2000;117:406-17)