Superior Airway Space Research Articles

Cephalometric Screening Assessment for Superior Airway Space Narrowing-Added Value of Three-Dimensional Imaging.

Background: Assessing the morphology of the superior airway space is a crucial diagnostic step in the treatment planning of patients with obstructive sleep apnea syndrome (OSAS) or prior to orthognathic surgery. The aim of this study is to evaluate the necessary scope of a two-dimensional cephalometric assessment and the necessity of three-dimensional imaging in the identification of superior airway space narrowing (SASN). Methods: The computed tomography studies of 100 non-obese, non-OSAS patients were evaluated and analyzed retrospectively. Multiplanar reconstructions were created and underwent cephalometric evaluation. The three-dimensional superior airway morphology was segmented and measured for the minimal cross-sectional area (Amin) and volume (V0). Patients were grouped according to Amin < 80 mm2 and V0 < 12 cm3. Cephalometric parameters (CPs) were analyzed according to Amin and V0 with an unpaired t-test, Pearson correlation, and ROC-curve analysis. Results: The CPs regarding sagittal airway space dimensions (IPAS, MPAS, SPAS) and mandibular body length (GoGn) show the strongest correlation to the three-dimensional minimal cross-sectional area (Amin). The ROC-curve analysis classifying for SASN led to an AUC of 0.86 for IPAS, 0.87 for MPAS, 0.88 for SPAS, and 0.63 for GoGn. Three-dimensional imaging may further improve the diagnostic accuracy in the identification of SASN for IPAS below 13.5 mm, MPAS below 10.2 mm, SPAS below 12.5 mm, and GoGn below 90.2 mm. Conclusions: Two-dimensional cephalometric sagittal airway space diameters and mandibular body length are useful initial screening parameters in the identification of superior airway space narrowing. Nevertheless, as the correlation of two-dimensional cephalometric parameters with three-dimensional upper airway space narrowing is varying and highly dependent on acquisition circumstances, indications for three-dimensional imaging, if possible, in the supine position to evaluate upper airway space morphology should be provided generously, especially in patients with low but normal airway space parameters in two-dimensional cephalometry.

Cephalometric changes associated with MAD therapy

Study objectives: The main objectives of this study were to assess the effect of mandibular advancement device (MAD) therapy on the upper airway morphology, as well as the occurence of dental and skeletal side effects following 1-year MAD therapy in patients with mild to moderate obstructive sleep apnea (OSA). Methods: In this study we included 15 patients with mild to moderate OSA treated with MAD therapy. All subjects underwent sleep study and lateral cephalometric radiography at baseline and at 1-year follow-up. Lateral cephalograms were analyzed with respect to relevant variables. Results: MAD therapy reduced apnea-hypopnea index (AHI) from 22.9±5.9 to 9.7±4.5 events/h (P&amp;lt;0.001) after 1-year of therapy. Oral area enclosure (3697.0±372.4 vs. 3381.5±336.4 mm2, P&amp;lt;0.001), superior airway space width (8.9±2.0 vs. 10.0±2.0 mm2, P=0.039), soft palate width (10.9±1.0 vs. 9.8±1.4, P=0.005) and length (45.4±3.8 vs. 43.9±4.2 mm, P=0.033) were significantly larger with the MAD intra-orally. Additionally, the tongue length decreased (84.1±5.3 vs. 80.7±5.9 mm, P=0.002), while the tongue height increased significantly (27.0±2.4 vs. 29.9±2.5 mm, P=0.003) with the MAD intra-orally. There were no significant changes in skeletal and dental cephalometric variables after 1 year of MAD therapy. Conclusions: Our results show significant enlargement of the upper airway dimensions with the MAD intra-orally in patients with mild to moderate OSA. Although there were no significant changes in skeletal and dental cephalometric variables after 1 year of MAD therapy, close follow-up during MAD therapy is advisable to prevent potentially relevant occlusal changes.

Quantifying Upper Airway Changes Following Mandibular Orthognathic Surgery.

The aim of this study was to quantify upper airway changes following mandibular orthognathic surgery. Treatment records of 50 patients who underwent mandibular orthognathic surgery were divided into 2 groups, that is, Group 1: Cases treated with Mandibular Advancement Surgery and Group 2: Cases treated with Mandibular Setback Surgery with 25 patients in each group. The Lateral Cephalogram and Acoustic Pharyngometry records of both groups were studied at T0 (01 week before surgery) and T1 (01 year postsurgery) for changes in linear airway measurements (Nasopharyngeal Airway Space - NAS, Superior Airway Space - SAS, Posterior Airway Space - PAS and Hypopharyngeal Airway Space (HAS)), hyoid bone position (Mandibular Plane Hyoid distance), mean area and mean volume. The percentage change and change in these parameters per millimeter advancement or setback of mandible at T1 was calculated. A significant increase in linear airway parameters (SAS and PAS); decrease in hyoid distance; and increase in volume and area of upper airway was observed at T1 in Group 1 and reverse was observed in Group 2. The change in airway parameters (SAS, PAS, mean volume and area) was more significant in Group 1 as compared to Group 2. In the current airway centric approach, meticulous assessment and prediction of long-term airway changes post surgery should be an integral part of ortho-surgical diagnosis and treatment planning and suitable modifications in the treatment plan must be made to cater for any potential adverse effects on airway.

Predictability of pharyngeal airway space dimension changes after orthognathic surgery in class II patients: A mathematical approach

IntroductionAngle Class II malocclusion due to mandibular retrognathia is a common dentofacial deformity. It is well known that mandibular advancement increases pharyngeal airway dimensions. The aim of this study was to evolve a mathematical method for predicting posterior pharyngeal airway space (PAS) changes based on 2D lateral cephalographic radiographs (LCRs) and expected extent of mandibular advancement prior to BSSO. Materials and methodsLinear regression analyses were performed in order to investigate the relation between the posterior airway space and mandibular advancement. LCRs where carried out to assess skeletal landmarks and pharyngeal airway space pre- (T0) and postoperatively (T1). To detect changes postoperatively, the posterior airway space was divided into three units: nasopharyngeal airway space (superior airway space — SPAS), oropharyngeal airway space (mid airway space — MAS) and hypopharyngeal airway space (inferior airway space — IAS). The differences between the distances of distinct measurement points (DIFF) were measured pre- and postoperatively. DOA referred to the distance of mandibular advancement and DP to the distance between the measurement points preoperatively. The parameters a, b1 and b2 were the regression coefficients that were determined separately for each unit (SPAS, MAS, and IAS). Results49 patients (16 male and 33 female) with a mean age of 27.2 years (SD: 10.09), ranging from 18 to 51 years, who underwent mandibular advancement surgery (BSSO) were enrolled in this study. The mean distance of mandibular advancement was 5.05 mm (SD: 1.63). Regarding SPAS and IAS, mandibular advancement did not affect dimensions significantly: SPAS DIFF, 0.33 mm ± 1.13 mm (b1, p = 0.0881; b2, p = 0.087); IAS DIFF, 0.66 mm ± 2.45 mm (b1, p = 0.342; b2, p = 0.765). DOA and DP did not influence DIFF significantly in both sections. Regarding MAS, the mean effect of mandibular advancement was an expansion of 2.47 mm ± 2.24. The linear regression model showed a statistically significant (b1, p = 0.0064; b2, p = 0.0240) influence of DOA and DP on DIFF in posterior airway dimensions pre- and postoperatively. DiscussionBased on preoperative LCR imaging data, a linear regression model was developed as a mathematical approach to allow prediction of PAS development in patients with Angle Class II malocclusions of different degrees. Increasing mandibular advancement was shown to be linked to increasing PAS, while a greater distance between the measuring points preoperatively led to smaller predicted PAS increases postoperatively. ConclusionPredicting pharyngeal airway space (PAS) development after mandibular advancement by analysing lateral cephalometric radiographs (LCR) may be useful in the screening and treatment of obstructive sleep apnea syndrome (OSAS) patients. Our mathematical approach is a simple and sustainable prediction tool based on LTR data for patients with Class II malocclusions.

Evaluation of Denture Wear on Upper Airway Dimensions and Oxygen Saturation in Completely Edentulous Patients

Background: Majority of the elderly people complain of difficulty in sleeping. Although the causes for the sleep disturbances may be multifactorial in nature, the sleep disordered breathing (SDB) is one of the primary disorder. The study was undertaken to study the effect of complete denture rehabilitation which could have profound impact on rehabilitation protocol on complete edentulous patients. Aim: The aim of this study is to cephalometrically evaluate the effect of complete denture rehabilitation on upper airway dimensions and position of hyoid bone and also to examine if complete denture rehabilitation influences oxygen saturation and degree of sleepiness by overcoming upper airway collapsibility. Material and Method: Of 30 edentulous patients who complained of snoring during sleep were selected for the study. The baseline lateral cephalogram of all the patients were taken by asking the patient to attain the natural head position. MAS (Minimal Airway Space), PAS (Posterior Airway Space), SAS (Superior Airway Space), MP-H (Perpendicular distance from hyoid bone to mandibular plane) were also recorded. The patients were also subjected to pulse oximetry test to assess the oxygen saturation and ESS (Epworth Sleepiness Scale) to assess the day time sleepiness. All these subjects were rehabilitated using conventional complete denture fabricated using standard prosthodontic protocol and after 6 weeks to 8 weeks they were subjected to same tests again with dentures in situ. Results: The results of this study showed no statistically significant difference on minimal airway space (MAS), posterior airway space (PAS), superior airway space (SAS), perpendicular distance from hyoid bone to mandibular plane (MP-H), epworth sleepiness scale (ESS) and oxygen saturation. Conclusion: Wearing the complete denture during night does not improve the airway space, oxygen saturation and day time sleepiness significantly among edentulous patients.

Evaluation of uvuloglossopharyngeal dimensions in patients with thalassemia intermedia and major

The uvuloglossopharyngeal dimensions (UGPDs) are assumed to be affected by thalassemia major (TM). Because thalassemia intermedia (TI) is a milder form without need for blood transfusions, this study aimed to evaluate whether the UGPDs in thalassemic patients are equally affected by the two forms. The study sample comprised 52 lateral cephalograms from thalassemic patients (31 TM; 21 TI) aged 12.98 ± 1.66 years. The control group comprised 25 lateral cephalograms from non-thalassemic subjects aged 13.64 ± 1.55 years with ANB > 3°. Linear measurements including tongue length (TGL), tongue height (TGH), soft palate length, uvula thickness (UT), superior airway space, middle airway space, inferior airway space, and mandibular plane to hyoid (MP–H) were recorded using AutoCAD 2007 software. Mean TGL, TGH, and MP–H in the thalassemic patient group were significantly smaller than those in the control group (all P < 0.05). Conversely, the mean UT was significantly greater than that in the control group (P < 0.001). The mean TGH, TGL, and MP–H in the control group were significantly greater than those in the TM and TI groups and the mean UT in the control group was significantly smaller than those in the TM and TI groups (all P < 0.05). There were significant differences in some airway components (TGL, TGH, MP–H, UT) between the thalassemic patient group and the control group based on lateral cephalograms as a reliable tool. However, there were no significant differences in these measurements between TM and TI patients.

Three-dimensional evaluation of superior airway space after orthognathic surgery with counterclockwise rotation of the maxillomandibular complex

Three-dimensional evaluation of superior airway space after orthognathic surgery with counterclockwise rotation of the maxillomandibular complex

Three-dimensional evaluation of superior airway space after orthognathic surgery with counterclockwise rotation and advancement of the maxillomandibular complex in Class II patients

The aim of this study was to assess changes in the superior airway space (SAS) in Class II patients undergoing orthognathic surgery with counterclockwise rotation of the maxillomandibular complex (MMC). A total of 23 patients (15 females and 8 males; mean age, 33 years) with symptoms of respiratory disease (mouth breathing) were studied. The patients were subjected to computed tomography analyses at two time intervals: T1 (preoperatively) and T2 (postoperative minimum of 6 months). The computed tomography images were exported to Dolphin Imaging 11.5 software to measure the surface area, minimum axial area, and volume of the SAS. The surgery (including a median mandibular advancement of 14 mm with an average rotation of 8 degrees) significantly increased the static SAS, with mean postoperative increases of 178 mm(2) in SA, 76.67 mm(2) in minimum axial area, and 10118.5 mm(3) in volume. A significant increase was also observed in the three-dimensional airspace following orthognathic surgery, which provided a greater permeability of the SAS in Class II patients. This confirmed the efficacy of this technique in the treatment of respiratory disorders.

Three-dimensional Evaluation of Superior Airway Space in Class II Patients Undergoing Orthognathic Surgery with Counterclockwise Rotation of the Maxillomandibular Complex

The aim of this retrospective study was to evaluate alterations in the superior airway space in Class II patients undergoing orthognathic surgery with counterclockwise rotation of Maxillomandibular Complex using Cone-beam computer tomography (CBCT) scans and the software program Dolphin Imaging® 11.5 (Dolphin Imaging and Management Solutions, Chatsworth,CA,USA) for three-dimensional measurement of surface area (AS) , minimum axial area (MAA) and volume (VOL) of the superior airway space. Twenty-three patients with a history of respiratory disorders were assessed, 15 females and 8 males with a mean age of 34.04 years (16 to 64 years). They were subjected to computer tomographies analyzes at two time intervals: T1 (preoperatively) and T2 (postoperative minimum of 6 months). The data obtained were tabulated and statistically analyzed. A t-Student and Wilcoxon paired test was used, with statistically significant results being obtained (p< 0.05), regarding an increase in superior airway space in patients undergoing orthognathic surgery with counterclockwise rotation of the MMC in this study.

Evaluation of Upper Airway Dimensional Changes and Hyoid Position Following Mandibular Advancement in Patients With Skeletal Class II Malocclusion

Class II skeletal malocclusion due to mandibular deficiency is considered a risk factor for sleep disorders due to oropharyngeal airway deficiencies. In view of the above, a prospective interventional study was undertaken to evaluate upper airway dimensional changes and position of hyoid bone by comparing pretreatment and posttreatment lateral cephalograms. The objective also included the establishment of the ratio of mandibular advancement to increase in airway dimensions. Pretreatment and posttreatment lateral cephalograms of 20 adults (13 females and 7 males) with skeletal class II malocclusion treated by combined orthodontics and bilateral sagittal split ramus osteotomy was evaluated for changes in posterior airway space (PAS), superior airway space (SAS), minimum airway space (MAS), hyoid bone position (MP-H), effective mandibular length (Co-Gn), mandibular corpus length (Go-Pg), and pogonion position (N perpendicular-Pg). The cephalograms were manually traced by a single operator and the data analyzed using MINITAB 13.2 version software. There was a statistically highly significant (P = 0.0001) increase in PAS, SAS, MP-H, Co-Gn, and Go-Pg. The mean ratio of mandibular advancement to increase PAS, SAS, and MAS was 1:0.35, 1:0.34, and 1:0.24, respectively. Hyoid bone moved superiorly and in an anterior direction by 2.1 ± 2.8 mm and was found to be statistically highly significant (P = 0.0001). The study showed an overall increase in airway dimension and improvement in hyoid position. Thus, the procedure may be considered beneficial in reducing upper airway collapsibility and preventing sleep disorders due to oropharyngeal airway deficiencies in skeletal class II malocclusion.

Evaluation of the relationship between obstructive sleep apnea syndrome severity and cephalometric and clinical variables

To evaluate the cephalometric features of patients with obstructive sleep apnea syndrome (OSAS) and to elucidate the relationship between the severity of OSAS and cephalometric and clinical variables. Materials and methods: Ninety-three patients (71M/22W) with OSAS were classified into 3 subgroups according to the apnea-hypopnea index (AHI). Various cephalometric and clinical measurements were carried out for all patients. Results: Inferior airway space (IAS), maximum soft palate thickness (MSPT), SNGoGn°, and distance of hyoid bone to mandibular plane (Hy-MPPerp) were found to be higher in severe OSAS for both sexes. Middle airway space, IAS, MSPT, and Hy-MPPerp were correlated positively with AHI; however, superior airway space (SAS) was correlated negatively. In the stepwise regression analysis, mean SaO2, neck circumferences for men, and mean SaO2 and uvula length (PNS-PA) for women were included in the model to estimate AHI properties. Conclusion: The values of IAS, MSPT, SNGoGn°, and Hy-MPPerp showed a tendency to increase with the severity of OSAS. Although the cephalometric variables used to estimate OSAS severity had no effect in men, PNS-PA was found to have an influence in women. However, it is thought that it is difficult to use cephalometric variables to estimate AHI severity in both sexes.

Obstructive Sleep Apnoea: Dental Implications &amp; Treatment Strategies

The management and treatment of patients who suffer from snoring and obstructive sleep apnoea (OSA) have long since been addressed by medical and specialist dental publications and were recently highlighted by a number of mainstream dental articles. These articles inform of the medical implications of the problem and the medical and dental treatment options available, but provide little technical information on constructing these appliances. The article reviews the concepts, rationale and technical aspects of appliance design and discusses clinical and financial issues. RATIONALE AND CONCEPTS OF APPLIANCE DESIGN Snoring is a sign of partial upper airway obstruction during sleep. Snoring and OSA are caused by abnormal airway (base of tongue and soft palate) anatomy and altered respiratory control mechanisms. Dental appliances may prevent snoring and OSA by modifying the position of the upper airway structures so as to enlarge and/or reduce collapsibility of the airway.[12345] Both the superior airway space (between the soft palate and posterior nasopharynx) and the posterior airway space (between the base of the tongue and posterior oropharynx) may be increased.[6] Three dimensional reconstructions of computed tomography and magnetic resonance imaging scans demonstrate significant increases in airway dimensions with the appliances.[78] The effectiveness of appliance therapy, however, depends on the severity of the sleeping disorder, the airway anatomy and whether the patient can tolerate the appliance. It is generally advocated for mild OSA and simple snoring (i.e. snoring in the absence of OSA) and moderate to severe OSA as an alternative to nasal continuous positive airway pressure (nCPAP) or craniofacial surgery.[9] The use of intra-oral appliances is simple, non-invasive, reversible and cost effective and may be the basis of definitive lifelong treatment. Originally there were three concepts for a dental appliance to modify the airway, which could be used alone or in combination depending on where the airway obstruction occurred: Soft palate lifting – the prosthesis lifts and/or stabilizes the soft palate, preventing vibration during sleep. Tongue retention – tongue-retaining devices (TRDs) incorporate an anterior hollow bulb, which generates a negative pressure vacuum when the tongue is inserted. The tongue is held forward, away from the posterior pharyngeal wall, opening up the airway. Owing to muscle anatomy, this appliance simultaneously modifies the position of the mandible. Mandibular repositioning – these appliances (MRAs) hold the mandible in an anteroinferior position, which, as a consequence of muscle attachment, indirectly brings the tongue forward, opening up the posterior airway (Figure 1). The repositioning may also stretch and reduce the collapsibility of the soft palate via its connection to the base of the tongue and increase the superior airway space. The soft palate lifting design is not often used because of patient tolerance and the fact that tongue posture rather than soft palate position is considered to have a significant influence on the patency of the upper airway.[10] An example of this type of appliance is clearly shown in the paper by Clark and Nako1no.5 Whilst TRDs directly move the tongue to open the airway, patient tolerance is not satisfactory. Obstructive Sleep Apnoea: Dental Implications & Treatment Strategies 2 of 6 When appliances are indicated the consensus appears to be a type of MRA, which Johal and Battagel consider most suitable for obstructions at the level of the tongue.[2] However, there is considerable variation with respect to the vertical and horizontal planes of mandibular repositioning and the material used for construction. MANDIBULAR REPOSITIONING CONSIDERATIONS Appliances for the treatment of snoring and OSA have been described with different degrees of horizontal and vertical repositioning. The most common mandibular repositioning dimension quoted is 50–75% of maximal protrusion (approximately 5–7 mm) with minimal vertical opening.[111215] The rationale for minimal opening is that, as the mandible opens, it rotates in an inferior and posterior direction. Concurrent posterior movement of the tongue and soft palate with wider opening may narrow the pharyngeal airway.7 An extensive review led by Ivanhoe found a variety of protrusive dimensions were associated with successful outcomes.[13] This, along with Lowe’s text [14] suggests that most protrusive positions are effective. MATERIAL CONSIDERATIONS To date either poly-vinyl vacuum-formed thermoplastic materials (soft or stiff blanks depending on the Shorehardness) or hard acrylic (predominantly heat cured) can be used. The choice of material often depends on appliance design and operator preference. To optimize retention for the vinyl appliances it is recommended that the flanges extend at least 3 mm past the gingival margin but, if softer vinyl is used, this depth should be increased.