Lateral cephalometric landmarks used in this study. S, Sella; N, nasion; ANS, anterior nasal spine; PNS, posterior nasal spine; A, point A; B, point B; Gn, gnathion; Go, gonion; G', Glabella; Pog', soft tissue pogonion; Ls, the most anterior projection of the upper lip vermillion; Li, the most anterior projection of the lower lip vermillion; Sn, subnasale; Me', soft tissue menton; STs, upper lip stomion; STi, lower lip stomion; U1a, upper incisor apex; L1a, lower incisor apex; U1i, upper incisor incisal point; L1i, lower incisor incisal point; Pr, Porion; Or, Orbitale; SnPerp, reference line constructed by passing a line through Sn and perpendicular to the Frankfurt horizontal plane (Po-Or).