Geometrical Approaches for the Accurate Identification of Normal Vertical Positions of Sella and Nasion Points in Cephalograms

Figure 2

Linear parameters. (1) S-Ba, the linear distance between S and Ba; (2) Ba-Ptm, the linear distance between Ba and Ptm; (3) Ba-PNS, the linear distance between Ba and PNS; (4) S-Ar, the linear distance between S and Ar; (5) Ar-Ptm, the linear distance between Ar and Ptm; (6) Ar-PNS, the linear distance between Ar and PNS; (7) S-Ptm, the linear distance between S and Ptm; (8) S-PNS, the linear distance between S and PNS; (9) S-FH, the linear perpendicular distance from S to FH plane, (10) N-FH, the linear perpendicular distance from N to FH plane. S-FH: N-FH, the ratio of S-FH and N-FH distances in %.