• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.51.1-51.8
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• 2019

Purpose: It has been reported before that the amount of pharyngeal airway space (PAS) significantly decreases following mandibular setback (MS) surgery in patients with mandibular prognathism (MP). Further, MP patients with an anterior open-bite (AOB) presentation may show a larger decrease in PAS compared with those without AOB. However, studies on postoperative PAS changes in MP patients with AOB remain rare. This study sought to evaluate changes in PAS and hyoid bone positioning following MS surgery in MP patients with and without AOB. Patients and methods: Twenty patients who underwent two jaw surgery involving MS movement were included. Patients were divided into a non-AOB group (n = 10; overbite > 2 mm) and an AOB group (n = 10; overbite < - 4 mm). Three-dimensional changes in PAS and hyoid bone positioning were compared and statistically evaluated pre- and postoperatively using computed tomography (CT). Results: The mean magnitude of MS was 6.0 ± 2.8 mm and 5.6 ± 3.2 mm in the non-AOB group and AOB group, respectively. The oropharyngeal volume and upper hypopharyngeal volume were significantly reduced after surgery in both the groups (p = 0.006 and p = 0.003), while the retroglossal cross-sectional area was significantly reduced only in the AOB group (p = 0.028). Although the AOB group showed a larger decrease in PAS, the difference was not statistically significant between the groups. The position of the hyoid bone showed significant posterior and inferior displacement only in the AOB group, while the vertical displacement of the hyoid bone showed a statistically significant difference between the two groups. Conclusion: PAS was significantly decreased after MS in both the groups, while only the AOB group presented a statistically significant reduction in the retroglossal cross-sectional area. Vertical displacement of the hyoid bone showed a statistically significant difference between the groups, while the PAS change was not. Surgeons should be aware of potential postoperative airway problems that may arise when performing MS surgeries.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권1호
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• pp.27-34
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• 2006

After orthognathic surgery in skeletal class III patients, the hyoid bone position and the upper airway dimension could be changed due to mandibular setback. There has been many studies about airway dimension of the patients with skeletal class II malocclusion or obstructive sleep apnea. but not with skeletal class III. The purpose of this study was to examine the change of position of the hyoid bone and the consequent change of airway space as the result of retrusion of mandible after orthognathic surgery in skeletal Cl III malocclusion patients. It is also to apply this results in predicting, diagnosing and treating the subsequent obstructive sleep apnea. Forty patients who were diagnosed as skeletal Cl III maloccusion, received orthoganthic surgery of both jaws including mandibular setback, and were followed up post-operatively for more than 6 months were selected. There were 10 male patients 30 female patients. The preoperative and postoperative lateral cephalograms were traced and the distances and angles were measured. The nasopharyngeal space increased postoperatively while the oropharyngeal space decreased. Except for the change of oroparyngeal space, the changes in male patients were greater than female patients. The hyoid bone moved in the posterior-inferior direction, and the change was greater in males than in females. If the postoperative mandibular setback is great, then a significant decrease of airway space and posterior and inferior movement of the hyoid bone were observed. This can result in symptoms related to obstructive sleep apnea. This result should be considered in the diagnosis and treatment planning of orthognathic surgery patients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권3호
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• pp.173-181
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• 2003

Purpose : This study was intended to evaluate the positional relationship between the hyoid bone and the mandible in patients with mandibular protrusion after mandibular set-back surgery by means of 3D-CT. Materials and methods : Preoperative(3 weeks before) and postoperative (6 weeks after) 3D-CT & cephalogram were taken on 32 patients(12 male, 20 female, mean age of 23.2) treated by bilateral sagittal split osteotomy with rigid fixation. The angular measurement on 3D-CT basilar view were deviation of Me & H, long axis angle of left & right cornu majus. The lineal measurement on 3D-CT basilar view were composed of intercondylar line and coordinates(x,y) of Me & H. The angular & lineal measurement of lateral cephalogram were composed of mandibular plane angle, SNA, SNB, ANB, FH-NA & FH-NB, and coordinates(x,y) of B, Pog, Me & H, PAS, Lpw, MPH and IAS. On the frontal cephalogram, deviation of Me were evaluated. Results : The mean mandibular set-back was 8.0mm horizontally and mandibular plane angle was slightly increased. The hyoid bone was displaced postero-inferiorly, the distance between MP(mandibular plane) and H(hyoid bone) was increased and the posterior airway space values (PAS, Lpw, IAS) were decreased. The coordinates Me(x,y), H(x,y) and deviation angle Me'& H' were revealed the strong positive correlation. Conclusion : The results revealed that the horizontal, vertical and transverse relationship of the mandibular and the hyoid bone movements were significantly correlated in patients performed mandibular set-back surgery.

• 대한치과교정학회지
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• 제17권1호
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• pp.7-13
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• 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).

• Imaging Science in Dentistry
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• 제50권2호
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• pp.105-115
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• 2020

Purpose: This study investigated the position of the hyoid bone and its relationship with airway dimensions in different skeletal malocclusion classes using cone-beam computed tomography (CBCT). Materials and Methods: CBCT scans of 180 participants were categorized based on the A point-nasion-B point angle into class I, class II, and class III malocclusions. Eight linear and 2 angular hyoid parameters(H-C3, H-EB, H-PNS, H-Me, H-X, H-Y, H-[C3-Me], C3-Me, H-S-Ba, and H-N-S) were measured. A 3-dimensional airway model was designed to measure the minimum cross-sectional area, volume, and total and upper airway length. The mean crosssectional area, morphology, and location of the airway were also evaluated. Data were analyzed using analysis of variance and the Pearson correlation test, with P values <0.05 indicating statistical significance. Results: The mean airway volume differed significantly among the malocclusion classes(P<0.05). The smallest and largest volumes were noted in class II (2107.8±844.7 ㎣) and class III (2826.6±2505.3 ㎣), respectively. The means of most hyoid parameters (C3-Me, C3-H, H-Eb, H-Me, H-S-Ba, H-N-S, and H-PNS) differed significantly among the malocclusion classes. In all classes, H-Eb was correlated with the minimum cross-sectional area and airway morphology, and H-PNS was correlated with total airway length. A significant correlation was also noted between H-Y and total airway length in class II and III malocclusions and between H-Y and upper airway length in class I malocclusions. Conclusion: The position of the hyoid bone was associated with airway dimensions and should be considered during orthognathic surgery due to the risk of airway obstruction.

• 대한치과교정학회지
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• 제30권5호
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• pp.579-589
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• 2000

혀와 설골의 위치가 안모형태와 어떤 양태로 상관성을 갖는지 비교평가하기 위해 69명의 성인군과 63명의 성장군에서 두부방사선계측사진을 얻었다. 성인군과 성장군에서 SN평면에 대해 큰 하악평면각을 갖는 군과 작은 하악평면각을 갖는 군으로 구분하여 다음과 같은 결론을 얻었다. 1. 혀의 높이는, 큰 하악평면각을 갖는 군보다는 작은 하악평면각을 갖는 군에서, 성인군보다는 성장군에서 높게 나타났다. 2. 설골의 수직적 높이는 큰 하악평면각을 갖는 군보다는 작은 하악평면각을 갖는 군에서, 성인군보다는 성장군에서 높게 나타났다. 3. 연령과 안모형태의 수직적 분류에 따른 설골의 전후방적인 위치는 차이가 없었다. 4. 두개저에 대한 설골의 기울기에 있어, 성인군보다 성장군에서 좀 더 가파른 경사도를 갖고 있었다.

• 구강회복응용과학지
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• 제22권4호
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• pp.271-281
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• 2006

Long term prediction of surgical result of skeletal class III has not been evaluated adequately because the stability of orthognathic surgery would be affected by not only set back amount of mandible but also many other factors like skeletal pattern, hyoid position, and airway size. The aimof this study is to discriminate the factors which affect the stability of post-treatment result of surgical outcome of sagittal split ramus osteotomy. We have collected 37 patients (male: 17, female: 20) from patients who have been treated at Orthodontic Department in Dankook University. The patients underwent 3 times Cephalometric X-ray taking at pre-, post-orthognathic surgery and after 12 months retention. The subjects were divided into 2 groups (Stable group: 21, Relapse group: 16) according to their relapse amount. We have taken following results from Students t-test and discriminant analysis. The discriminant factors which discern relapse and stable groupe among treatment change variables were BX and Ba-HY. Hyoid bone moved to posterior and inferior position due to surgery and repositioned superiorly and posteriorly during retention period. Skeletal patterns of the relapse group are smaller mandibular plane angle, anterior mandibular position, and greater distance from hyoid bone to cervical bone and mandible respectively.

• Advances in pediatric surgery
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• 제7권2호
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• pp.137-141
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• 2001

Thyroglossal duct cyst is ectodermal remnant, which may develop along the line of descent of the thyroid gland from the foramen cecum of the tongue to the pyramidal lobe of the thyroid gland. Meticulous dissection of the cyst and duct, along with the body of the hyoid bone is necessary to avoid recurrence. Eighty-one patients with thyroglossal duct cyst treated at Hanyang University Hospital between January 1980 and December 2000 were reviewed to determine the incidence and to analyze the result of management. The male-to-female ratio was 1.4:1(47:34) with a male preponderance. They are most commonly present at 3-8years(54.2 %) of age, but rarely present at infancy. The most common symptom was a painless midline neck mass(76.5 %, 62cases). Eighty-one patients underwent modified Sistrunk operation without evidence of recurrence. Eight-nine percent(72 cases) of these lesions were located between thyroid substance and hyoid bone, and 11 %(9 cases) were above the hyoid bone. There were 22 infected cysts(27.2 %). The Sistrunk operation is a gold standard for treating the thyroglossal duct cysts. For best results in thyroglossal duct cyst surgery, one should make every effort to remove the cyst intact in continuity with the body of the hyoid bone. In our institute, Sistrunk operation modified by the authors showed a good result.

• 대한치과교정학회지
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• 제27권4호
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• pp.569-584
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• 1997

본 연구는 상악골 급속확장술식 후 호흡변화와 연관된 두경부 자세의 변화와 이에 따른 설골 위치 변화의 양상을 알아보기 위하여 시행하였다. 평균연령이 12세 9개월이고 Hellman stage IIIc에서 adult stage까지의 인두강이 정상적이며 상악골 급속확장술식을 시행 한 Angle씨 III급 골격 양상의 남녀 환자 32명을 대상으로 하여 이들 중 상악골 급속확장술식 시행 후 두경부각도가 증가된 군을 A군으로, 감소된 군을 B군으로 분류하였고 대조군은 연구대상과 동일한 Hellman stage이며 평균연령 12세 7개월의 Angle씨 I급 골격양상을 띠는 남녀환자 23명으로 이들을 C군으로 하여 골격양상과 인두강크기, 두경부 자세, 설골 위치에 대한 항목을 연구하여 다음과 같은 결론을 얻었다. 1 골격양상과 인두강 비교 1) A, B군의 치료 전후 비교에서, 두 군 공히 하악이 하방경사되었고 인두강 크기는 변화가 없었다. 2) 세 군간의 치료 전후를 각각 비교한 결과, A, B군의 PMV에 대한 골격 양상과 인두강 크기는 정상이었다. 2. 두경부 자세 비교 1) A, B군의 치료 전후 비교에서, A군에서는 두경부 각도가 상방으로 B군은 두경부 각도와 하악하연이 하방으로 경사됨을 보였다. 2) 세 군간의 치료 전후를 각각 비교한 결과, 치료전에 두경부 각도가 A군은 정상적이었으며, B군은 정상보다 상방 경사짐을 보였다. 치료후에는 A, B군 모두 정상적인 두경부각도를 보였다. 3. 설골 위치 비교 1) A, B군의 치료 전후 비교에서, 두 군 공히 설골장축 각도의 변화가 없었고 전후방적으로 A군은 설골이 후방위치 되었으며 B군은 변화가 없었다. 수직적으로는 A군의 APHFH가 증가되었을 뿐 나머지 항목에서는 두 군 모두 변화가 없었다. 2) 세 군의 치료 전후를 각각 비교한 결과, 설골장축 각도는 A, B군 모두 정상적이었으며, 전후방적으로 치료전에 A군이 B, C군보다 설골이 전방에 위치되었으나 치료후에는 A, B군 공히 정상적 위치였었다. 설골의 수직적 위치는 치료 전후에 A, B군 모두가 정상적이었다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권4호
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• pp.294-305
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• 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.