"The pitfalls and merits of using commonly accepted orthodontic cephalometric analyses".
With these thoughts in mind, a realistic, systematic approach can be designed to better develop and interpret cephalometric tracings. After all landmarks are traced and located, connect Sella to Nasion to D point. The triangle formed by connecting these landmarks without other planar values interfering will facilitate evaluation of these three landmarks to each other. With the apex of the triangle formed at D point, the angle formed by Sella-D point and D Axis should be anterior to an iscosoles triangle position. If not, the patient is likely to evidence a vertical growth and mandibular retrognathism, or the Sella-Nasion pattern plane has a severely flat cant. In cases where this same apex (SDN) is severely anterior to an "iscosoles angle," this patient is likely to have either mandibular prognathism or a steep cant of the Sella-Nasion Plane (see Figs. 11 and 12). To determine the relative cant of Sella-Nasion, locate and trace the desired planar position of Frankfurt Horizontal using one of the three choices listed previously. If the Sella-Nasion Plane is 10 degrees or more greater than the cant of Frankfurt Horizontal, the Sella-Nasion plane will be inaccurate as a reference plane for A point, B point and D point gnathic relations, as well as Occlusal Plane to Sella-Nasion. Once it has been established which horizontal reference plan is to be used, the relative positions of the remaining planar values can be traced and compared. In so doing, more accurate interpretation of cephalometric data can be achieved without the puzzling conflicts with other analysis values that might otherwise occur.
Murray
T M
TM
Gibson General Hospital, Princeton, IN 47670, USA.
D002508:Cephalometry / Q000379:methods*; D005147:Facial Bones / Q000033:anatomy & histology; D006801:Humans; D008310:Malocclusion / Q000175:diagnosis*; D009970:Orthodontics / Q000379:methods; D012016:Reference Values; D015203:Reproducibility of Results; D012886:Skull / Q000033:anatomy & histology