Cephalometric identification of the 13 landmarks used in this study. S: sella, N: nasion, Or: orbitale, Po: porion, A: A-point, B: B-point, Pog: pogonion, Me: menton, UIB: upper incisor border, LIB: lower incisor border, PNS: posterior nasal spine, ANS: anterior nasal spine, Ar: articulare.