The reliability and variability of SN and PFH reference planes in cephalometric diagnosis and therapeutic planning of dentomaxillofacial malformations

Various interpretations of clinical and cephalometric data lead to differen t diagnostic and surgical planning in the study of dentoskeletal malformati ons. Many authors have identified this discrepancy as an incorrect position ing between the skeletal structures and the Frankfurt plane (PFH)-a plane t hat is used routinely for the sagittal measurement of the upper and lower j aw. The aim of this study was to establish a control method to verify the c orrect positioning of the sella-nasion point plane (SN) and the PFH. To fin d a reference plane, the authors concentrated their attention on measuring the intersecting angles between these two planes and the vertical posterior maxillary (PM) plane. Fifty patients (33 women and 17 men), all of whom we re aesthetically and structurally harmonious class I dentoskeletal types, w ere analyzed using this method. Student's t-test the Kolmogorov-Smirnov tes t, and Fisher's F-test were used for statistical analysis. The results were compared with those proposed by the University of Michigan. To achieve a c orrect diagnosis and to obtain good functional and cosmetic results in the treatment of these kinds of malformations, it is necessary to make use of t he PM vertical plane during cephalometric analysis.