Tongue and Hyoid Bone Positions and Its Relations to the Mandibular Anterior Teeth: A Cone-Beam Computed Tomography Study

Abstract

Objectives This study aimed to investigate the position of the tongue and hyoid bone at rest according to incisal relationships using cone beam computed tomography and to examine whether dentoskeletal measurements are correlated with these positions.Materials and Methods Participants were categorised into normal, open bite, cross-bite and combined open-crossbite groups according to overjet and overbite. Linear and volumetric measurements of tongue dimensions and positions of the tongue and hyoid bone were compared among the four groups using one-way analysis of variance and the Bonferroni post hoc test. Pearson correlation coefficients were calculated to evaluate the relationships of tongue and hyoid bone positions with dentoskeletal parameters.Results Downward and forward positions of the tongue and hyoid bone were observed in the cross-bite and open-crossbite groups. Overjet and mandibular incisor-to-mandibular plane angles were negatively correlated with all parameters of the vertical and horizontal tongue and hyoid bone positions. Horizontal skeletal parameters negatively correlated with tongue-to-palate distance, tongue tip ratio, oral cavity airway volume and horizontal hyoid bone position. Vertical skeletal parameters correlated with the horizontal position of the tongue and hyoid bone.Conclusion The downward and forward positions of the tongue and hyoid bone at rest were related to anterior cross-bite but not to anterior open bite, indicating that the tongue position was related to the most anteriorly positioned teeth. The inferior and anterior positions of the tongue correspond to a constricted maxilla, skeletal Class III relationship, retroclined mandibular incisors and negative overjet.