• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.26 no.2
• /
• pp.164-171
• /
• 2000

Purpose : This study was aimed at measuring the changes in the hyoid bone position, tongue position, and pharyngeal airway space in subjects with mandibular setback osteotomies. Methods : Twenty patients were evaluated retrospectively for their changes in pharyngeal airway space, tongue and hyoid bone positions. All patients underwent surgical mandibular setback using bilateral sagittal split osteotomies. The cephalometric analysis was performed preoperatively, and 1 week, 3-6 months, and 1 year postoperatively. Result : The hyoid bone moved inferiorly and posteriorly immediately after surgery, and it returned to the preoperative position during follow-up period. The nasopharyngeal airway space was not significantly changed after surgery. A considerable decrease in the oropharyngeal and hypopharyngeal airway spaces following mandibular setback surgery was found. The upper and lower tongue was posteriorly repositioned immediately after surgery. During follow-up period, the hypopharyngeal airway space and lower tongue posture returned to the preoperative positions, but the oropharyngeal airway space and upper tongue posture were not significantly changed. The position of pogonion remarkably changed to backward immediately after surgery, but slightly anterior advancement was found during follow-up period. Conclusion : Immediately after mandibular setback surgery, the oropharyngeal and hypopharyngeal airway spaces obviously decreased due to posterior and inferior repositions of the tongue and hyoid bone. During follow-up period, lower tongue and hyoid bone returned to the preoperative positions, it was related to advancement of the pogonion in this period. The narrowing of the oropharyngeal airway space and posterior movement of the upper tongue posture were relatively permanent after mandibular setback surgery. We suspected this phenomenon had an influence on maintaining the total volume of oral cavity against mandibular setback.

• Journal of Yeungnam Medical Science
• /
• v.5 no.2
• /
• pp.71-77
• /
• 1988

This study was made to investigate the influence of mouth breathing to tongue, mandible and hyoid bone position. It has been clinically suggested that the mouth breathing is induced by the respiratory dysfunction of nasopharyngeal airway causing by the Adenoids. The author used the 50 children, who were the nasal breathes with normal occlusion as the control group, and 50 children, who were mouth breathers with Adenoid as the experimental group. Results were as following: 1. In experimental group, the tongue was positioned more anterior and lower than that of the normal children. 2. In experimental group, the mandible was positioned more lower than that of the normal children. 3. In experimental group, the hyoid bone was positioned more anterior and lower than that of the normal children.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.42
• /
• pp.27.1-27.9
• /
• 2020

Background: Mandibular setback surgery can change the position of the mandible which improves occlusion and facial profile. Surgical movement of the mandible affects the base of the tongue, hyoid bone, and associated tissues, resulting in changes in the pharyngeal airway space. The aim of this study was to analyze the 3-dimensional (3D) changes in the hyoid bone and tongue positions and oropharyngeal airway space after mandibular setback surgery. Methods: A total of 30 pairs of cone-beam computed tomography (CBCT) images taken before and 1 month after surgery were analyzed by measuring changes in the hyoid bone and tongue positions and oropharyngeal airway space. The CBCT images were reoriented using InVivo 5.3 software (Anatomage, San Jose, USA) and landmarks were assigned to establish coordinates in a three-dimensional plane. The mean age of the patients was 21.7 years and the mean amount of mandibular setback was 5.94 mm measured from the B-point. Results: The hyoid bone showed significant posterior and inferior displacement (P < 0.001, P < 0.001, respectively). Significant superior and posterior movements of the tongue were observed (P < 0.05, P < 0.05, respectively). Regarding the velopharyngeal and glossopharyngeal spaces, there were significant reductions in the volume and minimal cross-sectional area (P < 0.001). The anteroposterior and transverse widths of the minimal cross-sectional area were decreased (P < 0.001, P < 0.001, respectively). In addition, the amount of mandibular setback positively correlated with the amount of posterior and inferior movement of the hyoid bone (P < 0.05, P < 0.05, respectively). Conclusion: There were significant changes in the hyoid bone, tongue, and airway space after mandibular setback surgery.

• The korean journal of orthodontics
• /
• v.16 no.2
• /
• pp.99-106
• /
• 1986

The author studied 21 adenoid hypertrophied children and 50 normal children by the horizontal, vertical and angular measurements to analyze, the effects of the lymphadenoid hypertrophy to the tongue, mandible, and hyoid bone position. The results were as follows; 1. The tongue of the Adenoid hypertrophy children was positioned mon anterior and lower than that of the normal children. 2. The horizontal, vertical, and angular measurements of the mandible position were larger in the experimental group and especially ANS to ME, PNS to MP, PTM to MP, PP to MP, FOP to MP showed statistically significant difference. 3. The measurements of the hyoid bone position were also larger in the experimental group.

• The korean journal of orthodontics
• /
• v.27 no.2
• /
• pp.231-243
• /
• 1997

This study was carried out in order to find out the changes of the pharyngeal airway, hyoid bone and head posture before and after tonsillectomy in functional class III malocclusion patients. For this study, 21 Angle's class I patients and 21 Angle's class III patients, totally 42 subjects were chosen. The results were as follows; 1. In comparison to Class I group, tongue was more anteriorly and hyoid bone was more inferiorly positioned in functional Class III group 2. In comparison to pre-tonsillectomy, tongue was more posteriorly positioned and larger nasopharynx depth was shown in post-tonsillectomy. In post tonsillectomy, the hyoid bone was displaced posteriorly and superiorly and counterclockwise rotation was shown. 3. The level of significance for the correlation shown was 5 percent (p<0.05) indicating that: The change of nasopharyx depth was correlated to the inclination of lower incisors. Vertical change of tongue posture was correlated to the hyoid axis change. Vertical change of hyoid bone was correlated to the horizontal change of hyoid bone, craruocervical inclination. The change of craniocervical inclination was correlated to the inclination of lower incisors. 4. After the tonsillectomy, counterclockwise rotation of hyoid axis was associated with decease of hya-NL and large nasopharyngeal airway. High posture of the tongue was associated with decrease of hya-NL. Posterior posture of the tongue was associated with increase of h-hl,and decrease of hya-ba-n.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.31 no.4
• /
• pp.294-305
• /
• 2009

Purpose: This retrospective study evaluated the changes in hyoid bone and tongue positions as well as oral cavity volume after mandibular setback by BSSRO. Materials and Methods: 18 Koreans who underwent BSSRO to correct mandibular prognathism were studied. Lateral cephalograms were taken and traced preoperatively (T0), immediately (T1) and approximately 6 months postoperatively (T2). Submentovertex radiograghs were taken and traced before surgery (T0) and about 6 months after surgery (T2). The area and volume of oral cavity, the vertical and horizontal dimensions of the hyoid bone and tongue dorsum were measured. Results: Mandibular setback surgery resulted in a significant reduction of lower oral cavity volume. The hyoid bone displaced posteroinferiorly immediately after surgery, and it tended to return to its original vertical position at 6 month after mandibular setback by BSSRO. The retropalatal space around tongue was maintained and the retrolingual space around tongue was reduced immediately postoperatively. The readaptation of tongue was not evident for that the follow up period was not long enough. No significant statistical correlations between the amounts of mandibular setback and the changes of oral cavity volume were observed. Conclusion: Mandibular setback surgery resulted in a significant reduction of lower oral cavity volume, which was most likely attributable to the posterior movement of the mandible. More subjects and long-term observations should be performed to assess the changes of oropharyngeal configuration following mandibular setback surgery.

• The korean journal of orthodontics
• /
• v.17 no.1
• /
• pp.7-13
• /
• 1987

This study was conducted to clarify the relationship of hyoid bone position to tongue position and mandible when malocclusion is categorized in the bilateral and in the vertical components. Five groups of samples (normal occlusion, unilateral and bilateral cross-bite, openbite, deep-bite) were selected for his investigation by utilizing the cephalograms. On the basis study, the following conclusions were obtained; 1. In the normal group. the mean hyoid position (H-M) was $9.83{\pm}4.27mm$. The mean distance of hyoid body to tongue dorsum (H-T) was $52.17{\pm}6.70mm$. The ratio of H-M/H-T was $18.59\%$. 2. In all malocclusion groups, the hyoid position (H-M) was found to be larger than that of the norm except the deep overbite group 3. The tongue dorsum position (H-T) was increased, compared to that of norm, in all malocclusion groups. 4. Hyoid position (H-M) was found to show high correlation to the ratio of H-M/H-T, H-T, PI-T (0.890, 0.699, 0.455). 5. The hyoid position (H-M) was found to show low correlation to the measurements of mandible, but among them the ODI was found to show conversely a little higher correlation against hyoid position (H-M).

• The korean journal of orthodontics
• /
• v.30 no.5 s.82
• /
• pp.579-589
• /
• 2000

The purpose of this study was to evaluate the position of tongue and hyoid bone in relation to vortical facial patterns in the adult and child. Lateral cephalograms taken in adults(63 cases, 11.7 years in average age) and children(69 cases, 22.6 years in average age) were traced and measured about position and posture of tongue and hyoid bone using the horizontal and vertical reference lines. The angle of mandibular plane to SN Plane was employed to classify the samples into groups of hypodivergent and hyperdivergent. The comparison of the tongue/hyoid bone measurements between hypodivergent group and hyperdivergent group in the adult and child were statistically executed with Student's f-test. The results were as follows, 1. The tongue height was lower in the hyperdivergent group than in hypodivergent group, and higher in children than in adults. 2. The vertical height of hyoid bone was higher in hypodivergent group than in hyperdivergent group and also higher in children than in adults. 3. The anteroposterior position was of no significant difference in relation to age or vortical facial pattern. 4. The inclination of hyoid bone in relation to cranial base was steeper in children than in adults.

• The korean journal of orthodontics
• /
• v.23 no.4 s.43
• /
• pp.693-705
• /
• 1993

The purpose of this study was to investigate the functional adaptation of the tongue, the hyoid bone, the digastric muscle and the upper airway and the variables predicting postoperative stability following orthognathic surgery in patients with mandibular prognathism. 18 patients were selected(8 men and 10 women) for this study, who had received orthognathic surgery. Their lateral cephalograms, those were taken preoperatively, immediate postoperatively and over 6 months follow-up, were traced and analysed. The results were as follows : 1. The downward displacement of the hyoid bone and extended head posture were recognized, right after operation. Statistically significant correlations were found between the changes of the mandibular position and the digastric muscle and the change of head posture during operation. 2. The tongue was displaced downward following the hyoid displacement postoperatively. Statistically significant correlations were found between the change of the mandibular position and the change of the distance of the tongue and hard palate, and between the change of head posture and the changes of the upper airway sizes, the digastric muscle and the hyoid position during over 6 month's follow-up. 3. The change of the distance of the tongue and hard palate was the most significant factor for prognosis during over 6 month's follow-up. 4. There were no variables before operation to predict the postoperative stability and the constriction of the upper airway.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.24 no.2
• /
• pp.347-359
• /
• 1994

The reproducibility of cephalography in repeated exposures were studied by tracing and photographic subtraction. The materials consisted of 50 pairs of 'same day' radiograph taken under identical conditions. The evaluation included skull, cervical column, hyoid bone, pharynx, tongue, soft tissue profile resulting 43 items in tracing, and 19 items in photographic subtraction. The results obtained from the differences between each pair were as follows: 1. The means and standard deviations by tracing of skull, cervical column, hyoid bone, pharynx, tongue, soft tissue profile were 0.34±0.62㎜, 1.02±1.59㎜, 1.37±1.78㎜, 0.55±1.16㎜, 0.51±1.51㎜, 0.15±0.3㎜ each. 2. The means and standard deviations by photographic subtraction of skull, cervical column, hyoid bone, pharynx, tongue were 0.09±0.35㎜, 0.70±0.95㎜, 1.22±1.33㎜, 0.53±0.86㎜, 0.27±0.41㎜ each.