• The korean journal of orthodontics
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• v.53 no.1
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• pp.35-44
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• 2023

Objective: Surgically assisted maxillary protraction is an alternative protocol in severe Class III cases or after the adolescent growth spurt involving increased maxillary advancement. Correction of the maxillary deficiency has been suggested to improve pharyngeal airway dimensions. Therefore, this retrospective study aimed to analyze the airway changes cephalometrically following surgically assisted maxillary protraction with skeletal anchorage and Class III elastics. Methods: The study population consisted of 15 Class III patients treated with surgically assisted maxillary protraction combined with skeletal anchorage and Class III elastics (mean age: 12.9 ± 1.2 years). Growth changes were initially assessed for a mean of 5.5 ± 1.6 months prior to treatment. Airway and skeletal changes in the control (T0), pre-protraction (T1), post-protraction (T2), and follow-up (T3) periods were monitored and compared using lateral cephalometric radiographs. Statistical significance was set at p < 0.05. Results: The skeletal or airway parameters showed no statistically significant changes during the control period. Sella to nasion angle, N perpendicular to A, Point A to Point B angle, and Frankfort plane to mandibular plane angle increased significantly during the maxillary protraction period (p < 0.05), but no significant changes were observed in airway parameters (p > 0.05). No statistically significant changes were observed in the airway parameters in the follow-up period either. However, Sella to Gonion distance increased significantly (p < 0.05) during the follow-up period. Conclusions: No significant changes in pharyngeal airway parameters were found during the control, maxillary protraction, and follow-up periods. Moreover, the significant increases in the skeletal parameters during maxillary protraction were maintained in the long-term.

• The korean journal of orthodontics
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• v.50 no.4
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• pp.238-248
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• 2020

Objective: To investigate the effects of the long-term use of a maxillary protraction facemask with miniplate (FM-MP) on pharyngeal airway dimensions in growing patients with cleft lip and palate (CLP). Methods: The study included 24 boys with CLP (mean age, 12.2 years; mean duration of FM-MP therapy, 4.9 years), divided into two groups according to the amount of A point advancement to the vertical reference plane (VRP): Group 1, > 4 mm; Group 2, < 2 mm; n = 12/group. After evaluating the skeletodental and airway variables using lateral cephalograms acquired before and after FM-MP therapy, statistical analyses were performed. Results: Group 1 showed greater forward and downward displacements of the posterior maxilla (posterior nasal spine [PNS]-horizontal reference plane [HRP]; PNS-VRP), greater increase in ANB, more forward tongue position (tongue tip-Pt vertical line to Frankfort horizontal plane), and greater increase in the oropharynx (superior posterior airway space [SPAS]; middle airway space [MAS]) and upper nasopharynx (PNS-adenoid2) than did Group 2. While maxillary advancement (A-VRP and PNS-VRP) correlated with increases in SPAS, MAS, and PNS-adenoid2, downward displacement of the PNS (PNS-HRP) correlated with increases in SPAS, MAS, PNS-adenoid1, and PNS-adenoid2, and with a decrease in vertical airway length (VAL). Mandibular forward displacement and decrease in mandibular plane correlated with increases in MAS. Conclusions: FM-MP therapy had positive effects on the oropharyngeal and nasopharyngeal airway spaces without increases in VAL in Group 1 rather than in Group 2. However, further validation using an untreated control group is necessary.

• The korean journal of orthodontics
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• v.52 no.5
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• pp.345-353
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• 2022

Objective: To investigate airway volumes using cone-beam computed tomography (CBCT) by skeletal patterns, sex, and cervical vertebral maturation (CVM) stages in Korean adolescents. Methods: The sample consisted of pretreatment CBCT and cephalograms of 95 adolescents (aged 12-19) obtained out of 1,611 patients examined for orthodontic treatment from 2018 to 2020 in Kyungpook National University Dental Hospital. The samples were classified into two sex groups; three skeletal pattern groups, four chronological age groups and four CVM stages. Nasopharyngeal volumes (NPV), oropharyngeal volumes (OPV), total pharyngeal airway volume (TAV) and minimum cross-sectional area (MCA) measurements were taken from the CBCT. Multiple linear regression analyses to find out which one of the independent variables are good predictors for airway variables. Significant factors were analyzed by two-way multivariate analysis of variance (MANOVA) then multiple comparisons were analyzed using a t-test, and Fisher least significant difference. Results: Age, sex, CVM, and Sella-Nasion-B point have significant influence on airway variable. Males and females showed similar patterns of change in chronological age groups 1-3; however, males had larger NPV, OPV, and MCA at CVM in group 4. According to CVM stages, males had larger OPV, TAV, and MCA at CVM stage 6 (p-value: 0.019, 0.021, 0.015, respectively) and no sex differences at CVM stages 3, 4, and 5. Conclusions: Skeletal patterns have an effect on airway volume. Sex differences were found in CVM 6.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.1
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• pp.9-13
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• 2012

Introduction: To evaluate the 3-dimensional changes in the pharyngeal airway of skeletal class III patients after bimaxillary surgery. Materials and Methods: The study sample consisted of 18 Korean patients that had undergone maxillary setback or posterosuperior movement and mandibular bilateral sagittal split osteotomy setback surgery due to skeletal class III malocclusion (8 males, 10 females; mean age of 28.7). Cone beam computed tomography was taken 1 month before and 6 months after orthognathic surgery. Preoperative and postoperative volumes of the nasopharyngeal, oropharyngeal, and laryngopharyngeal airways and minimum axial areas of the oropharyngeal and laryngopharyngeal spaces were measured. Moreover, the pharyngeal airway volume of the patient group that had received genioplasty advancement was compared with the other group that had not. Results: The nasopharyngeal and laryngopharyngeal spaces did not show significant differences before or after surgery. However, the oropharyngeal space volume and total volume of pharyngeal airway decreased significantly (P<0.05). The minimum axial area of the oropharynx also decreased significantly. Conclusion: The results indicate that bimaxillary surgery decreased the volume and the minimum axial area of the oropharyngeal space. Advanced genioplasty did not seem to have a significant effect on the volumes of the oropharyngeal and laryngopharyngeal spaces.

• The korean journal of orthodontics
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• v.53 no.6
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• pp.358-364
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• 2023

Objective: This study aimed to three-dimensionally evaluate the pharyngeal airway space (PAS) of patients with anterior open bite (AOB) by using cone-beam computed tomography (CBCT) and compare the findings with those obtained in individuals with normal occlusion. Methods: The open bite group (OBG, n = 25) consisted of patients with an anterior overbite of -3 mm or less, while the control group (n = 25) consisted of age- and sex-matched individuals with an anterior overbite of 1-3 mm, Angle Class I malocclusion (1° ≤ point A-nasion-point B angle ≤ 4°), and a normodivergent profile (22° ≤ Frankfort mandibular plane angle ≤ 28°). After the CBCT data were reconstructed into a three-dimensional image, the PAS was segmented into four parts, and the volume of each part was measured. Pharyngeal airway length (PAL) and the area and transverse width of the part showing minimal constriction were also measured. Pearson's correlation analysis was used to evaluate the correlation between changes in the PAS and the amount of anterior overbite. Results: The OBG showed a significantly narrower airway space in the nasopharyngeal, hypopharyngeal, and total airway volumes. The OBG also showed a significantly smaller area and transverse width of the part with minimal constriction. The OBG showed a significantly longer PAL, but there was no correlation between the amount of anterior overbite and the changes in PAS. Conclusions: The PAS was associated with AOB. Patients with AOB had a narrower PAS and a smaller part showing minimal constriction.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.39
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• pp.22.1-22.9
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• 2017

Background: Two-jaw surgery including mandibular and maxillary backward movement procedures are commonly performed to correct class III malocclusion. Bimaxillary surgery can reposition the maxillofacial bone together with soft tissue, such as the soft palate and the tongue base. We analyzed changes of pharyngeal airway narrowing to ascertain clinical correlations with the prevalence of snoring after two-jaw surgery. Methods: A prospective clinical study was designed including a survey on snoring and three-dimensional (3D) computed tomography (CT) in class III malocclusion subjects before and after bimaxillary surgery. We conducted an analysis on changes of the posterior pharyngeal space find out clinical correlations with the prevalence of snoring. Results: Among 67 subjects, 12 subjects complained about snoring 5 weeks after the surgical correction, and examining the 12 subjects after 6 months, 6 patients complained about the snoring. The current findings demonstrated the attenuation of the largest transverse width (LTW), anteroposterior length (APL), and cross-sectional area (CSA) following bimaxillary surgery given to class III malocclusion patients, particularly at the retropalatal level. The average distance of maxillary posterior movements were measured to be relatively higher (horizontal distance 3.9 mm, vertical distance 2.6 mm) in case of new snorers. Conclusions: This study found that bimaxillary surgery could lead to the narrowing of upper airway at the retropalatal or retroglossal level as well as triggering snoring in subjects with class III malocclusion. Based on the current clinical findings, we also found that upper airway narrowing at retropalatal level may contribute to increasing the probability of snoring and that polysonography may need to be performed before orthognathic surgery in subjects with class III malocclusion.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.5
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• pp.401-406
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• 2011

Purpose: The purpose of this study was to investigate changes in the position of the hyoid bone and soft palate and the amount of airway space after bilateral sagittal split ramus osteotomy (B-SSRO). Methods: This study is a review of lateral cephalometric tracings of 30 patients who underwent B-SSRO with setbacks at Kyunghee Dental Hospital from 2005 to 2009. Lateral cephalograms were taken before (T0), within one month (T1), and more than six months after the surgery (T2). Results: The hyoid bone at T1 changed significantly towards the inferoposterior position. At T2, it had significantly moved superiorly, but not anteriorly. At T1, the nasopharyngeal space, extending from the posterior nasal spine to the posterior pharyngeal space, decreased significantly, but did not show a significant increase at T2. The nasopharyngeal space, extending from the middle of soft palate to the posterior pharyngeal space, decreased significantly at T1, but did not show a significant decrease at T2. The oropharyngeal airway space decreased significantly at T1 and did not return to its original position at T2. The hypopharyngeal space, extending from the anterior to the posterior pharyngeal space at the level of the most anterior point of the third cervical vertebrae, slightly decreased at T1, but the amount was insignificant; however, the amount of decrease at T2 was significant. The hypopharyngeal space extending from the anterior to the posterior pharyngeal space at the level of the lowest point of the third cervical vertebrae, decreased significantly at T1 but returned to its original position at T2. Conclusion: B-SSRO changes the position of the hyoid bone and muscles inferoposteriorly. These change allows enough space for the tongue and prevent airway obstruction. Airway changes may be related to post-operative edema, posterior movement of the soft palate, anteroposterior movement of the hyoid bone, or compensation for decreased oral cavity volume. The position of the pogonion which measures anterior relapse after surgery did not show significant differences during the follow-up period.

• Sleep Medicine and Psychophysiology
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• v.12 no.2
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• pp.105-110
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• 2005

The pathogenesis and mechanism of obstructive sleep apnea (OSA) has been under investigation for over 25 years, but its etiology and mechanism remains elusive. Skeletal (maxillary and/or mandibular hypoplasia or retrodisplacement, inferior displacement of hyoid) and soft tissue (increased volume of soft tissue, adenotonsillar hypertrophy, macroglossia, thickened lateral pharyngeal walls) factors, pharyngeal compliance (increased), pharyngeal muscle factors (impaired strength and endurance of pharyngeal dilators and fixators), sensory factors (impaired mechanoreceptor sensitivity, impaired pharyngeal dilator reflexes), respiratory control system factors (unstable respiratory control) and so on facilitate collapse upper airway. Therefore, OSA may be a heterogeneous disorder, rather than a single disease entity and various pathogenic factors contribute to the OSA varies person to person. As a result, patients may respond to different therapeutic approaches based on the predominant abnormality leading to the sleep-disordered breathing.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.38.1-38.6
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• 2015

Background: The posterior movement of mandible was known as the main cause of the changes in the pharyngeal airway space (PAS) and the postoperative obstructive sleep apnea (OSA). The purpose of this study was to know the changes of PAS and position of hyoid bone. Methods: Lateral cephalographies of 13 patients who had undergone sagittal split ramus osteotomy (SSRO) setback surgery were taken preoperatively (T1), postoperatively within 2 months (T2), and follow-up after 6 months or more (T3). On the basis of F-H plane, diameters of nasopharynx, oropharynx, and hypopharynx were measured. The movements of the soft palate, tongue, and hyoid bone were also measured. Results: The amount of mandible setback was $7.5{\pm}3.8mm$. In the measurements of PAS, there was a statistically significant decrease of $2.8{\pm}2.5mm$ in nasopharynx (P < 0.01), and $1.7{\pm}2.4mm$ in oropharynx (P < 0.01) were observed after surgery. The hypopharynx decreased $1.0{\pm}2.1mm$ after surgery and continuously decreased $1.0{\pm}2.8mm$ at follow-up. The changes in hyoid bone position showed the posterior movement only after surgery and posteroinferior movement at follow-up. Conclusions: The PAS such as nasopharynx, oropharynx, and hypopharynx showed relatively high correlation with the amount of mandibular setback. The change of resistance in upper airway may be important for the prevention of OSA after mandibular setback surgery.

• The korean journal of orthodontics
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• v.40 no.3
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• pp.145-155
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• 2010

Objective: Lateral cephalometric radiographs have been the main form of resource for assessing two dimensional anteroposterior airway changes. The purpose of this study was to evaluate the three dimensional volumetric change in the upper airway space in Class III malocclusion patients who underwent mandibular setback surgery. Methods: Three dimensional cone-beam computed tomographs (CBCT) and their three dimensional reconstruction images were analyzed. The samples consisted of 20 adult patients (12 males and 8 females) who were diagnosed as skeletal Class III and underwent mandibular setback surgery. CBCTs were taken at 3 stages - Baseline (1.8 weeks before surgery), T1 (2.3 months after surgery), and T2 (1 year after surgery). Pharyngeal airway was separated according to the reference planes and reconstructed into the nasopharynx, the oropharynx and the hypopharynx. Measurements at Baseline, T1, and T2 were compared between groups. Results: The result showed the volume of the pharyngeal airway decreased significantly 2.3 months after surgery (p < 0.001) and the diminished airway did not recover after 1 year post-surgery. The oropharynx was the most decreased area. Conclusions: These findings suggest that mandibular setback surgery causes both short-term and long-term decrease in the upper airway space.