Are Hyoid Bone and Tongue the Risk Factors Contributing to Postoperative Relapse for Mandibular Prognathism?

Figure 1

Reference lines and landmarks used in the lateral cephalometric analysis. S: sella. N: nasion. ANS: anterior nasal spine. PNS: posterior nasal spine. Me: the most inferior point on the mandibular symphysis. G: the most prominent point of the mandibular symphyseal posterior border. H: hyoid bone, the most superior and anterior point of hyoid bone. V: vallecula epiglottica. Tm: midpoint of tongue dorsum, the point of tongue intersecting by G-PNS line. -axis: constructed by drawing a line through nasion 7° up from SN line. -axis: constructed by drawing a line through sella (S) perpendicular to the -axis. H-G: distance between H and G. H-V: distance between H and V. Tongue depth: distance between Tm and G. Tongue base length: distance between V and G. G-PNS-ANS angle. H-PNS-ANS angle. G-H-V angle.