Proposed cephalometric diagnosis for osteogenic obstructive sleep apnea (OSA): the mandibular/pharyngeal ratio.

: The purpose of this laboratory study is to devise a simple, diagnostic test to assess possible osteological deficiency as a probable cause of OSA. Modern day skulls of fifty males and forty eight females of Tuscan origin and an additional seventy-five skulls, from India, with their cephalograms were used for this study. Mandibular length and antero-posterior dimension of the nasopharynx--pharyngeal tubercle (PhT) to posterior nasal spine (PNS)--were measured on the Tuscan skulls. The nasopharynx was similarly measured on the Indian skulls and readings multiplied by 1.14, the magnification factor of the cephalometric apparatus used. The PhT-PNS distance was then plotted on the cephalogram of Indian skulls with point PhT at the basiocciput. The possible presence of an osteogenic etiology of OSA can be determined by comparison of the mandibular/pharyngeal ratio obtained from the skull cephalograms to that of the individual patient.