“…10,15,[18][19][20] In studies using cephalometric measurements, various reference planes were used to examine vertical and horizontal changes. 1,[20][21][22][23][24][25][26][27][28][29] Frequently used ones among these planes are Sella Nasion plane or the plane ±7 degrees angled to this plane 10,11,19,20,24,25,[30][31][32][33] and Frankfort horizontal 9,15,34 as the horizontal reference plane, and the planes drew from Nasion or Sella point to these planes as the vertical plane. 9,10,15,19,24,25,30,32,34 Frankfort horizontal was selected as an HRL, and the perpendicular to the HRL through the Porion point was taken vertical reference line.…”