• The korean journal of orthodontics
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• v.28 no.4 s.69
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• pp.547-561
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• 1998

Obstructive sleep apnea (OSA) is a disorder characterized by repetitive episode of upper airway collapse during sleep. Recent studies showed that not only the anatomic factors but the physiologic factors of the upper airway also have effcts on the occurrence of apnea and that the genioglossus muscle also plays an important role in the maintenance of the upper airway. A variety of therapies were performed to treat OSA, and among them the use of mandibular repositioning appliances showed reasonable results. But there is still a lack of research on the structural and physiological mechanism upon the use of mandibular repositioning appliances. The author selected 26(male 17, female 9) OSA patients that came to the Yonsei University Dental Hospital, Department of Orthodontics, and 20 normal adults (male 10, female 10) and took cephalometric radiographs of them in a supine position before and after the placement of the mandibular repositioning appliance to see the structural changes of the upper airway and compare the therapeutic effects between the two groups. We also studied the waking genioglossus muscle activity in OSA patients and investigated the difference in the electromyogram of the genioglosssus muscle upon the change in body posture and the use of mandibular repositioning appliance. Following results were obtained. 1. Among the cephalometric measurements of the upper airway structure, the length of the soft palate, maximum thickness of the soft Palate and SPAS, MAS, VAL, H-H1, MP-H showed statistically significant differences between the normal and OSA groups, but the IAS and EAS showed no statistically significant differences between the two groups. 2. In both the normal and OSA groups, as the epiglottis moved forward on wearing the mandibular repositioning appliance, the epiglottis level of the upper airway increased and the maximum thickness of the soft palate changed and the hyoid bone also moved forward, but the IAS in both groups showed various results and the effect of the mandibular repositioning appliance on the structure of the upper airway was different in the two groups. 3. Upon changing the position, the electromyogram of the genioglossus muscle showed a increasing tendency but there was no statistically significant differences, and when the mandibular repositioning appliance were worn there was a statistically significant increase in the electromyogram of the genioglossus muscle in both the upright and supine positions. The mandibular repositioning appliances not only have an effect on the anatomical structure of the upper airway but also on the physiology of the upper airway. There are different responses to the use of mandibular repositioning appliance between the normal and OSA groups therefore it could be considered to have the different physiology of the upper airway between the two groups.

• The korean journal of orthodontics
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• v.53 no.5
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• pp.317-327
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• 2023

Objective: This study aimed to evaluate the association between low tongue position (LTP) and the volume and dimensions of the nasopharyngeal, retropalatal, retroglossal, and hypopharyngeal segments of the upper airway. Methods: A total of 194 subjects, including 91 males and 103 females were divided into a resting tongue position (RTP) group and a LTP group according to their tongue position. Subjects in the LTP group were divided into four subgroups (Q1, Q2, Q3, and Q4) according to the intraoral space volume. The 3D slicer software was used to measure the volume and minimum and average cross-sectional areas of each group. Airway differences between the RTP and LTP groups were analyzed to explore the association between tongue position and the upper airway. Results: No significant differences were found in the airway dimensions between the RTP and LTP groups. For both retropalatal and retroglossal segments, the volume and average cross-sectional area were significantly greater in the patients with extremely low tongue position. Regression analysis showed that the retroglossal airway dimensions were positively correlated with the intraoral space volume and negatively correlated with A point-nasion-B point and palatal plane to mandibular plane. Males generally had larger retroglossal and hypopharyngeal airways than females. Conclusions: Tongue position did not significantly influence upper airway volume or dimensions, except in the extremely LTP subgroup.

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

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.443-448
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• 2015

Obstructive sleep apnea (OSA) is a syndrome characterized by the repetitive episodic collapse of the upper airway. Maxillomandibular advancement surgery is one of the most effective surgical treatment methods in treating obstructive sleep apnea. The advancement of both maxill and mandible can enlarge the cross-sectional areas and volumes of the postero-superior airway. The purpose of this study is to analyze flow patterns in the upper airway before and after maxillomandibular advancement surgery. Here, we analyzed flow phenomena of inspiration and expiration to prevent obstructive sleep apnea patient from happening side effect. Modeling of the upper airway carried out from clinical CT scanned images. We used time-dependent values for boundary condition. CFD analyses were performed and evaluated section of minimum area (SMA), compared with patient inside upper airway before and after maxillomandibular advancement surgery in SMA, and negative pressure effects. The study showed the greatest enlargment of the section of minimum cross-sectional area. Moreover, the velocity and the negative airway pressure were decreased. According to the result of this study, the maxillomandibular advancement surgery stabilizes the airflow in the postero-superior airway of OSA patients.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.2
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• pp.148-156
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• 2007

Purpose: The aim of this study is the changes of upper respiratory airway space in patients with mandibular prognathism after 2-jaw orthognathic surgery in patients with skeletal classs III malocclusion. Method: We measured the lines between selected upper airway landmarks on lateral cephalometric x-ray films of skeletal class III 64 persons who had not been operated yet, were 6 months after operation. The test subjects were divided into 3 groups according to maxillary movement, as follows; maxillary advancement (MA) group, maxillary posterior impaction (MPI) group, maxillary posterior impaction and superior repositioning (MPI+MSR) group. Result: In this study, nasopharyngeal airway space in MPI+MSR group was significantly increased after operation (p<0.05). Oropharygeal and hypopharyngeal airway space in MA group and MPI group were significantly decreased after operation (p<0.05). From hyoid bone to anterior mandible point distance in MA group and MPI group were significantly decreased after operation (p<0.05). Conclusion: Oropharygeal and hypopharyngeal airway space were influenced more by mandibular set-back than maxillary movement. Maxillary movement surgery as well as mandibular setback surgery should be taken into consideration in order to minimize symptoms related to obstructive sleep apnea syndrome after operation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.2
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• pp.88-93
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• 2017

Objectives: Any change in maxilla and mandible position can alter the upper airway, and any decrease in the upper airway can cause sleep disorders. Thus, it is necessary to assess airway changes after repositioning of the maxilla and mandible during orthognathic surgery. The purpose of this study was to evaluate linear and volumetric changes in the upper airway after bimaxillary surgery to correct class III malocclusion via cone-beam computed tomography (CBCT) and to identify correlations between linear and volumetric changes. Materials and Methods: This was a prospective cohort study. CBCTs from 10 class III patients were evaluated before surgery and three months after. The Wilcoxon one-sample test was used to evaluate the differences in measurements before and after surgery. Spearman's rank correlation coefficient was used to test the correlation between linear and volumetric changes. Results: The results show that the nasopharyngeal space increased significantly, and that this increase correlated with degree of maxillary advancement. No significant changes were found in volumes before and after surgery. A correlation was found between linear and volumetric oropharyngeal changes. Conclusion: Bimaxillary surgical correction of class III malocclusion did not cause statistically significant changes in the posterior airway space.

• Tuberculosis and Respiratory Diseases
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• v.43 no.3
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• pp.449-454
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• 1996

Functional upper airway obstruction due to vocal cord dysfunction is being increasingly recognized and has been variously described as "Munchausen's stridor", "Emotional laryngeal wheezing", "Nervous asthma". It's features are symptoms of acute reversible recurrent dyspnea associated with an inspiratory stridor, normal anatomy of the upper airway, demonstration of variable severe exthrathoracic upper airways obstruction with pathologic adduction of the vocal cord at bronchoscopy. The patients with this condition are frequently misdiagnosed as asthma and the diagnosis is often delayed. So they can present a serious medical problem and are exposed to the complication of treatment and investigation. We report a case of functional upper airway obstruction due to vocal cord dysfunction who showed paradoxical vocal cord motion at bronchoscopy and typical features of variable exthrathoracic obstruction on Flow-volume loop during a symptomatic period.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.96-102
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• 2020

Oral cancer surgery changes the morphologic characteristics of the human upper airway. These changes can affect the flow patterns. In this study, computational fluid dynamics (CFD) simulations with transient solver were performed to numerically investigate the air flows in the human upper airways depending oral cancer surgery. 3D reconstructed models were obtained from 2D CT images of one patient. For the boundary condition, the realistic breathing cycle of human was applied. The hydraulic diameters of cross-sections for post-surgical model are changed greatly along streamwise direction, so these variations can cause higher wall shear stress and flow disturbance compared to pre-surgical model. The recirculation flows observed in the protruding region result in the relatively large pressure drop. These results can be helpful to understand the flow variations after resection surgery of oral cancer.

• The Journal of the Korean dental association
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• v.53 no.12
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• pp.926-934
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• 2015

Obstructive sleep apnea (OSA), most common respiratory disorder of sleep, is characterized by intermittent partial or complete occlusions of the upper airway due to loss of upper airway dilating muscle activity during sleep superimposed on a narrow upper airway. Termination of these events usually requires arousal from sleep and results in sleep fragmentation and hypoxemia, which leads to poor quality of sleep, excessive daytime sleepiness, reduced quality of life and numerous other serious health consequences. Untreated OSA may cause, or be associated with, several adverse outcomes, including daytime sleepiness, increased risk for motor vehicle accidents, cardiovascular disease, and depression. Various treatments are available, including non-surgical treatment such as medication or modification of life style, continuous positive airway pressure (CPAP) and oral appliance (OA). Skeletal surgery for obstructive sleep apnea (OSA) aims to provide more space for the soft tissue in the oropharynx to prevent airway collapse during sleep. Conventional surgical techniques include uvopalatopharyngoplasty(UPPP), genioglossus advancement (GA), and maxillomandibular advancement (MMA). Surgical techniques, efficacy and complications of skeletal surgery are introduced in this review.

• The korean journal of orthodontics
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• v.39 no.2
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• pp.72-82
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• 2009

Objective: The purpose of this study was to investigate the structural changes of the hyoid bone and upper airway after orthognathic surgery for skeletal class III anterior open bite patients, and make comparisons with normal occlusion. Methods: Pre- and post-operative computed tomography (CT) examinations were performed on 12 skeletal class III anterior open bite patients who were treated with mandibular setback osteotomy. Using the V-works $4.0^{TM}$ program, 3-dimensional images of the total skull, mandible, hyoid bone, and upper airway were evaluated. Results: In the Class III open bite group, the hyoid bone were all positioned anteriorly, compared to the Normal group (p < 0.05). The angle between the hyoid plane and mandibular plane in the Class III openbite group before surgery was greater than in the Normal group (p < 0.05), and the difference increased after surgery (p < 0.01). In the Class III openbite group, the volume of the upper airway decreased after surgery (p < 0.001) and the volume of the upper airway was smaller than the Normal group before and after surgery (p < 0.001). Conclusions: The narrow upper airway space in skeletal Class III openbite patients decreased after mandibular setback osteotomy. This may affect the post-surgical stability.