Investigation of the effects of miniscrew-assisted rapid palatal expansion on airflow in the upper airway of an adult patient with obstructive sleep apnea syndrome using computational fluid-structure interaction analysis

Effects of minimally invasive surgical and miniscrew-assisted rapid palatal expansion (MISMARPE) on the nasal cavity and upper airway: a comparative cohort study

This study was performed to evaluate the impact on the upper airway and nasal cavity of a new minimally invasive surgical and miniscrew-assisted rapid palatal expansion (MISMARPE) technique for the treatment of adult patients with transverse maxillary deficiency, in comparison to surgically assisted rapid palatal expansion (SARPE). Computed tomography scans of 21 MISMARPE and 16 SARPE patients were obtained preoperatively (T0) and at the end of the activation period (T1) and analysed. Linear and volumetric measurements were performed in the dental, alveolar, nasal cavity, and oropharynx regions. Generalised estimating equations were used to consider the intervention time and surgery type, and their interaction. In both groups, measurements were increased at T1 (P < 0.001), except for oropharynx volume (P > 0.05). A greater expansion in nasal cavity floor and median palatal suture was shown for MISMARPE when compared to SARPE (P < 0.001), with the same degree of expander activation (P = 0.094). A trapezoidal (coronal plane) and 'V' shape (axial plane) expansion pattern, was observed after MISMARPE. Both surgical techniques were effective for maxillary expansion in adults. However, MISMARPE was performed without osteotomy of the pterygomaxillary suture, in an outpatient setting and with local anaesthesia.

Does Miniscrew-Assisted Rapid Palatal Expansion Influence Upper Airway in Adult Patients? A Scoping Review

(1) Objective: This scoping review evaluates the effects of miniscrew-assisted rapid palatal expansion (MARPE) on different regions of the upper airway in adult patients and investigates various methods of measurement. (2) Methods: The search encompassed Pubmed, Cochrane Library, Scopus and Web of Science. This review was conducted following the PRISMA_ScR guidelines, and the inclusion criteria for examined studies were chosen in accordance with the PICOS framework. (3) Results: Seven studies were included in this review, comprising four retrospective studies, one prospective and two case reports. All studies involved the use of Cone Beam Computed Tomography (CBCT) for measurements of the areas of interest. The percentage of increase in the volume of the nasal cavity varied between 31% and 9.9%, depending on the study. Volumetric variations in the nasopharynx were reported as increases between T0 (before expansion) and T1 (immediately after expansion) of 6.4%, 20.7% and 14.1%. All studies considered T0 before expansion and T1 immediately after expansion. Only one study evaluated remote follow-up to assess if the results were maintained after one year. (4) Conclusions: MARPE appears to lead to a statistically significant increase in the upper airway, especially in the nasal cavity and nasopharynx immediately after expansion. However, further prospective and retrospective trails with long-term controls are required to verify the effects of MARPE on the upper airway.

An adult case of unilateral posterior crossbite caused by maxillary transverse deficiency treated with miniscrew-assisted rapid palatal expansion

This report describes the successful treatment of an adult case of unilateral posterior crossbite caused by maxillary transverse deficiency with miniscrew-assisted rapid palatal expansion (MARPE). A female patient aged 35.5 years presented with masticatory disturbance, facial asymmetry, and unilateral posterior crossbite. She was diagnosed with unilateral posterior crossbite with a skeletal Class III jaw-base relationship and high mandibular plane angle. Her maxillary right and mandibular bilateral second premolars were congenitally absent, and the maxillary left second premolar was impacted. After the improvement of the posterior crossbite with MARPE, 0.018″ slot lingual brackets were placed on the maxillary and mandibular dentition. The total active treatment period was 22 months, and acceptable occlusion with a functional Class I relationship was achieved. Pretreatment and posttreatment cone-beam computed tomography images showed the disarticulation of the midpalatal suture after MARPE, and changes in the dental and nasomaxillary structures, nasal cavity, and pharyngeal airway. The case results demonstrate that MARPE produces greater skeletal expansion with minimal buccal tipping of the molars. MARPE may be effective for the treatment of maxillary transverse deficiency in adult patients.

Short-term outcomes in the upper airway with tooth-bone-borne vs bone-borne rapid maxillary expanders

BACKGROUND

This study compared the area and minimal section of the nasal cavity, nasopharynx, oropharynx, and hypopharynx in cases treated with different methods of microimplant-assisted expansion.

METHODS

Based on a pilot study to calculate the sample size, 30 patients with transverse maxillary deficiency over 14 years of age were retrospectively selected. These patients had received two different types of microimplant-assisted maxillary expansion treatment (MARPE and BAME). The patient underwent Cone-Beam computed tomography (CBCT) before and after treatment (mean time 1.5 months) with MARPE or BAME and upper airway measurements (volume and minimum cross-sectional area) were taken to assess upper airways changes and compare changes between the groups. A paired sample t-test was performed to evaluate the T0-T1 change of airway measurements obtained with MARPE and BAME, and a student t-test to compare changes in airway measurements between MARPE and BAME.

RESULTS

This investigation shows a statistically significant increase in total nasopharyngeal airway volume (0.59 ± 1.42 cm3; p < 0.01), total oropharyngeal airway volume (3.83 ± 7.53 cm3; p < 0.01) and minimum oropharyngeal cross-section (53.23 ± 126.46 mm2; p < 0.05) in all cases treated with micro-screw assisted expansion. The minimal cross-sectional area of the oropharynx ((79.12 ± 142.28 mm2; p < 0.05) and hypopharynx (59.87 ± 89.79 mm2; p < 0.05) showed significant changes for cases treated with BAME. As for the comparison between cases treated with MARPE and BAME, no differences in upper airway changes have been observed, except for the minimum cross-sectional area of the nasal cavity, which increases for MARPE (52.05 ± 132.91 mm2) and decreases for BAME (-34.10 ± 90.85 mm2).

CONCLUSIONS

A significant increase in total area and minimal section at the level of nasopharynx and oropharynx was observed in cases treated with BAME. Regarding the comparison of MARPE and BAME treatments, no differences were found in the total airway volume and minimal section in upper airway except for the minimum cross section of the nasal cavity that increases for MARPE and decreases for BAME.

The effects of miniscrew-assisted rapid palatal expansion on the upper airway of adults with midpalatal suture in the last two degrees of ossification

BACKGROUND

Transverse deficiencies of the maxillary basal bone have been treated in adult patients using miniscrew-assisted rapid palatal expansion (MARPE) therapy. However, the midpalatal suture's degree of ossification may affect the upper airway dimensions. This study compared the volumetric changes of the total upper, retropalatal, retroglossal airways, and the minimal transverse airway constriction after MARPE therapy in patients with midpalatal suture in the last stages of ossification.

METHODS

This controlled clinical trial included a total of 20 adult patients (mean age 24.5 ± 6.2 years) with maxillary atresia treated with MARPE. Preoperative (T0) cone-beam computed tomography scans were used to determine the degree of midpalatal suture ossification. Two groups were formed considering the last two stages of sutural ossification "D" or "E" (n = 10 per group). After 120 days of the therapy (T1), cone-beam computed tomography assessments were performed to compare the pre and post-treatment outcomes. The total upper, retropalatal, and retroglossal airways and the minimal transverse airway constriction were evaluated. The three-dimensional reconstruction was performed with OsiriX MD software. The comparisons were carried out using mixed models for repeated measures at fixed time points (α = 0.05).

RESULTS

Groups D and E showed no significant difference for any of the analyzed parameters (P > 0.05). Both groups showed a statistically significant increase for all airway segments after the treatment with MARPE (P < 0.05). The total upper airway increased (11.6% and 16.1%) for groups D and E, respectively (P = 0.3356).

CONCLUSIONS

MARPE therapy resulted in dimensional gains of the upper airway for adult patients, irrespective of the intermaxillary sutural degree of ossification.

Management of Class III Malocclusion and Maxillary Transverse Deficiency with Microimplant-Assisted Rapid Palatal Expansion (MARPE): A Case Report

Microimplant-assisted rapid palatal expansion (MARPE) has been demonstrated successfully in maxillary expansion in late adolescence and adulthood. The maxillary advancement accompanied by expansion is frequently anticipated, which is beneficial for the treatment of class III malocclusion. Airway volume increase can also be noted in some cases from the measurement of cone beam computerized tomography (CBCT) after expansion. The objective of this case report is to demonstrate the feasibility of applying MARPE on late adolescence patients with maxillary transverse deficiency and to present the changes in transverse and anteroposterior dimensions as well as the volume increase in velopharyngeal airway after MARPE. A 15-year-old female presented class III skeletal pattern. She had maxillary transverse deficiency with moderate crowding and posterior/anterior crossbites. Maxillary Skeletal Expander (MSE; Biomaterials Korea Inc.) type-2 was used as a MARPE device in this case. After four weeks of maxillary expansion, a significant amount of expansion was achieved and the anterior crossbite was spontaneously corrected. Fixed appliance treatment was commenced four weeks after MARPE with 0.022-slot preadjusted brackets (MBT prescription). Temporary anchorage devices (TADs) were placed over the mandibular buccal shelves for posterior teeth distalization and crowding relief. After 25 months of treatment, the facial profile was improved with maxillary advancement (SNA: 83° to 83.5°) and mandibular backward rotation (SNB: 83° to 82°; SN-MP: 34.5° to 35°). In this case, MARPE not only engenders significant transverse correction but also aids in anteroposterior change. The treatment effects of maxillary advancement and mandibular backward rotation can lead to a more esthetic profile in skeletal class III cases.

Changes in the nasal and pharyngeal airway volume with miniscrew-assisted rapid palatal expansion appliances

Objectives:

The purpose of this study was to assess the volumetric changes in the nasal and pharyngeal airway volume in patients with maxillary transverse deficiency treated with miniscrew-assisted rapid palatal expansion (MARPE) appliances.

Material and Methods:

The pre- and post-treatment cone-beam computed tomography scans of 20 subjects who underwent treatment with the MARPE appliance as part of their orthodontic treatment were included in the study. Pre- and post-expansion airway volume measurements of the nasal cavity, nasopharynx, and oropharynx were measured. Linear measurements of the skeletal structures surrounding the nasal cavity were taken to assess the pattern of airway expansion. Paired t-tests were used to evaluate nasal and pharyngeal airway volume changes with expansion. Pearson correlation test was utilized to assess the relationship between nasal and pharyngeal volume changes.

Results:

A total of 17 out of 20 samples had a successful split of the mid-palatal sutures. A significant increase in nasal airway volume (12.0%) was found post-expansion. In addition, a significant increase in linear measurements of the nasal cavity base width in the frontal plane (7.1%) and both the anterior and posterior widths in the transverse dimension (9.4% and 3.4%, respectively) were found. Significant positive correlations were found between airway volumes and increase in width of the maxillary expansion appliance.

Conclusion:

The effects of maxillary expansion with a MARPE appliance include an increase in nasal cavity volume, but not the nasopharyngeal and the oropharyngeal airway volume. The nasal cavity expands in a triangular pattern in both the frontal and transverse dimensions following orthopedic expansion with the MARPE appliance. Increase in airway volume is a result of the increase in width of the maxillary expansion appliance.

Effects of the Nasal Cavity Complexity on the Pharyngeal Airway Fluid Mechanics: A Computational Study

The impact of the human nasal airway complexity on the pharyngeal airway fluid mechanics is investigated at inspiration. It is the aim to find a suitable degree of geometrical reduction that allows for an efficient segmentation of the human airways from cone-beam computed tomography images. The flow physics is simulated by a lattice Boltzmann method on high-performance computers. For two patients, the flow field through the complete upper airway is compared to results obtained from three surface variants with continuously decreasing complexity. The most complex reduced airway model includes the middle and inferior turbinates, while the moderate model only features the inferior turbinates. In the simplest model, a pipe-like artificial structure is attached to the airway. For each model, the averaged pressure is computed at different cross sections. Furthermore, the flow fields are investigated by means of averaged velocity magnitudes, in-plane velocity vectors, and streamlines. By analyzing the averaged pressure loss from the nostrils to each cross section, it is found that only the most complex reduced models are capable of approximating the pressure distribution from the original geometries. In the moderate models, the geometry reductions lead to overpredictions of the pressure loss in the pharynx. Attaching a pipe-like structure leads to a higher deceleration of the incoming flow and underpredicted pressure losses and velocities, especially in the upper part of the pharynx. Dean-like vortices are observed in the moderate and pipe-like models, since their shape comes close to a [Formula: see text]-bend elbow pipe.

Experimental study on the influence of model variations on the airway occlusion of an obstructive sleep apnea patient

This study deals with the analysis of model parameters to mimic the airway collapse of an obstructive sleep apnea patient during nasal breathing. Different material properties and geometry variations of a patient-specific airway model are analyzed in detail. The patient-specific airway geometry is obtained from MRI data. A completely rigid model is compared to two partly elastic variations with different elasticities. Furthermore, the influence of the nasal cavities and the treatment effect of a mandibular protrusion are studied. Rigid model parts are 3D-printed and elastic parts cast from silicone. The models are analyzed under the impact of a transient airflow which is realized through a computer controlled piston pump. The results suggest, that, for moderate deformations, the elasticity of the soft tissue replicate influences rather the level of the pressure drop inside the airway than the shape of the pressure curve. The same suggestion can be made for the influence of the nasal cavities. Often, the spatial location of the minimum pressure is taken as the collapse site of the airway geometry. This study demonstrates, that the spatial locations of the minimum pressure and the maximum deformation do not match. This reveals the importance of a coupled approach of soft tissue and airflow analysis in the search of the collapse site and therefore the best treatment option. A treatment effect of the mandibular protrusion can be anticipated with an accurate patient-specific airway model.

Open oral cavity has little effects on upper airway aerodynamics in children with obstructive sleep apnea syndrome: A computational fluid dynamics study based on patient-specific models

Obstructive sleep apnea syndrome (OSAS) is a common disorder with recurrent pharyngeal airway collapse and sleep disruption. Recently, great progress has been made in investigating the physical mechanism of OSAS development and treatment using computational fluid dynamics (CFD). However, previous studies always neglected the oral cavity artificially in the patient's upper airway CFD model, but did not give any specific explanation. The oral cavity effect on the OSAS upper airway flow is still a matter of unclear. This paper reconstructed the patient-specific upper airway models based on the cone beam computed tomography images of ten children subjects (seven boys and three girls) and used CFD to simulate both the steady and unsteady expiration and inspiration states in the upper airway model with or without the oral cavity. A series of pressure measurement experiments based on the in vitro 1:1 scaled airway model were performed to validate the reliability of the present CFD methods. Finally, the CFD results indicate that the open oral cavity is almost a region of flow stasis with constant pressure, and both the upper airway aerodynamics with and without the oral cavity have the similar trends, with the maximum average relative difference less than 6%. The present study shows that the open oral cavity causes very little impacts on the upper airway flow of the children patients with OSAS using the nasal respiration only, and confirms the reasonability of ignoring the oral cavity for CFD simulation.

Computational Fluid Dynamics Analysis of Nasal Airway Changes after Treatment with C-Expander

The use of the C-expander is an effective treatment modality for maxillary skeletal deficiencies which can cause ailments and significantly reduce life expectancy in late adolescents and young adults. However, the morphological and dynamic effects on the nasal airway have not been reported. The main goal of this study was to evaluate the nasal airway changes after the implementation of a C-expander. A sample of nine patients (8 females, 1 male, age range from 15 to 29 years) was included. The morphology parameters and nasal airway ventilation parameters of pretreatment and posttreatment were measured. All study data were normally distributed. A paired t-test was used to evaluate the changes before and after treatment. After expansion, the mean and standard deviation values of intercanine maxillary width (CMW) and intermolar maxillary width (MMW) increased from 35.75 ± 2.48 mm and 54.20 ± 3.17 mm to 37.87 ± 2.26 mm (P < 0.05) and 56.65 ± 3.10 mm (P < 0.05), respectively. The nasal cavity volume increased from 20320.00 ± 3468.25 mm³ to 23134.70 ± 3918.84 mm³ (P < 0.05). The nasal pressure drop decreased from 36.34 ± 3.99 Pa to 30.70 ± 3.17 Pa (P < 0.05), while the value of the maximum velocity decreased from 6.50 ± 0.31 m/s to 5.85 ± 0.37 m/s (P < 0.05). Nasal resistance dropped remarkably from 0.16 ± 0.14 Pa/ml/s to 0.08 ± 0.06 Pa/ml/s (P < 0.05). The use of C-expander can effectively broaden the area and volume of the nasal airway, having a positive effect in the reduction of nasal resistance and improvement of nasal airway ventilation. For patients suffering from maxillary width deficiency and respiratory disorders, a C-expander may be an alternative method to treat the disease.

Decreased maxillary sinus volume is a potential predictor of obstructive sleep apnea

OBJECTIVES

To investigate the associations between nasal airway volume and the presence and severity of obstructive sleep apnea (OSA) in adults.

MATERIALS AND METHODS

The medical records of adult patients who visited the sleep clinic at University Hospital between June 2013 and April 2017 and underwent overnight polysomnography for the diagnosis of obstructive sleep apnea were reviewed retrospectively. Using computed tomography, the volumes of the nasal airways and maxillary sinuses were measured, and associations with the presence and severity of OSA were analyzed while controlling for the effects of possible confounders such as lateral cephalometric variables, maxillary widths, tongue/hyoid position, and soft palate dimensions.

RESULTS

Comparison between normal subjects and patients with OSA revealed that the latter had decreased ratios of maxillary sinus volume to whole nasal airway volume (P = .029) than normal subjects. OSA severity was greater in those with inferior positions of the hyoid (P = .010), in older patients (P = .011), and in those with high body mass index (P = .001). The volume of the total nasal airway or maxillary sinuses were not associated with OSA severity.

CONCLUSIONS

A decreased ratio of maxillary sinus volume to whole nasal airway volume is associated with adult OSA. However, OSA severity is not associated with either maxillary sinus volume or whole nasal airway volume.

A comparative analysis of aerodynamic and anatomic characteristics of upper airway before and after mini-implant-assisted rapid maxillary expansion

INTRODUCTION

The objective of this research was to observe changes in aerodynamics and anatomic characteristics of the upper airway after mini-implants assisted rapid maxillary expansion and to evaluate the correlation between the 2 changes of the upper airway in young adults.

METHODS

Thirty consecutive patients (mean age, 23.82 ± 3.90 years; median, 24.5 years; 9 males, 21 females) were involved. Cone-beam computed tomography was taken before activation and over 3 months. Three-dimensional models of the upper airway were reconstructed on the basis of cone-beam computed tomography. The anatomic characteristics of the upper airway, including volume, area, transverse, and sagittal diameter, were measured. The aerodynamic characteristics of the upper airway were calculated on the basis of 3-dimensional models using computational fluid dynamics. The correlation between the changes in aerodynamics and anatomic characteristics of the upper airway was explored.

RESULTS

The enlargements of the volume of the total pharynx, nasopharynx, and oropharynx were found (9.99%, 20.7%, and 8.84%, respectively). The minimum cross-sectional area increased significantly (13.6%). The airway resistance (R) and maximum velocity (V_max) decreased significantly in both the inspiration and expiration phase (inspiration: R, -26.8%, V_max, -15.7%; expiration: R, -24.7%, V_max, -16.5%). The minimum wall shear stress reduced significantly only in the inspiration phase (-26.3%). The correlations between decreased R and increased volume and minimum cross-sectional area were observed.

CONCLUSIONS

Mini-implants assisted rapid maxillary expansion is an effective device for improving anatomic characteristics represented by the total volume of the upper airway and minimum cross-sectional area, which contributed to the respiratory function depending on the favorable changes of aerodynamic characteristics including resistance, velocity, and minimum wall shear stress.

Nasomaxillary effects of miniscrew-assisted rapid palatal expansion and two surgically assisted rapid palatal expansion approaches

This retrospective study was performed to evaluate nasomaxillary changes in 36 patients at an advanced stage of skeletal maturity who underwent miniscrew-assisted rapid palatal expansion (MARPE) or surgically assisted rapid palatal expansion (SARPE) with/without an alar base cinch. Cone beam computed tomography images taken before and after expansion were analysed. Changes in the width of the dental arch (D66S, D66I), maxillary base (MxMol), and nasal floor and nasal cavity in the molar and canine regions (NaFMol, NaFCan, NaCMol, NaCCan) were compared, as well as changes in the choanal aperture (CA) and nasal soft tissue (NW). The MARPE technique produced smaller dental changes (D66S; P=0.025) and greater nasomaxillary expansion (MxMol, P=0.010; NaCMol, P=0.016; NaCCan, P=0.017; NaFMol, P=0.001; CA, P=0.002) than both SARPE techniques. Changes in NW did not differ significantly between the groups (P=0.200). MARPE uniformly increased the anterior and posterior widths of the nasal cavity. SARPE expanded the nasal cavity in a 'V-shape' pattern. Changes in the nasal cavity and choanal aperture related to the amount of dental arch expansion were greater for MARPE than for SARPE. All three approaches increased the width of the nasal soft tissue, although the cinch in SARPE limited this increase.

Rapid Maxillary Expansion Has a Beneficial Effect on the Ventilation in Children With Nasal Septal Deviation: A Computational Fluid Dynamics Study

Nasal septal deviation (NSD) is one of the most common nasal diseases. Different from common clinical examination methods, computational fluid dynamics (CFD) can provide visual flow information of the nasal cavity. The dimension and volume of the nasal cavity are easily affected by rapid maxillary expansion (RME). The purpose of this study was to use CFD to evaluate the effect of RME on the aerodynamics of the nasal cavity in children with maxillary transverse deficiency and NSD. Computational fluid dynamics was implemented after 3D reconstruction based on the CBCT of 15 children who have completed RME treatment. After treatment, the volume increases in the nasal cavity, nasopharynx, oropharynx, and pharynx were not statistically significant. The wall shear stress of the nasal cavity after RME, 1.749 ± 0.673 Pa, was significantly lower than that before RME, 2.684 ± 0.919 Pa. Meanwhile, the maximal negative pressure in the pharyngeal airway during inspiration was smaller after RME (-31.058 Pa) than before (-48.204 Pa). This study suggests that RME has a beneficial effect on nasal ventilation. The nasal airflow became more symmetrical in the bilateral nasal cavity after RME. Pharyngeal resistance decreased with the reduction in nasal resistance and the increase in the volume of oropharynx after RME.

The role of micro-implant-assisted rapid palatal expansion (MARPE) in clinical orthodontics — a literature review

A maxillary transverse deficiency is a common craniofacial problem. Rapid palatal expansion (RPE) has been traditionally considered for the treatment of children and young adolescents, but this is not applicable in late adolescents or adults due to the ossification of facial sutures. A surgically assisted rapid palatal expansion (SARPE) was initially advocated for this group of patients, but the surgical procedure is associated with morbidity. As temporary anchorage devices (TADs) have been recently and popularly applied in clinical orthodontics, micro-implant-assisted rapid palatal expansion (MARPE) has been employed to facilitate maxillary expansion in skeletally mature patients. There have been various proposed MARPE designs and the outcomes appear promising. The aim of the present article is to discuss the role of MARPE in clinical orthodontics by reviewing its background, design, indications, treatment effects, stability, and limitations in the current literature. The treatment effects of two types of MARPE, bone-borne and tooth-bone-borne (hybrid), will be individually assessed.

Miniscrew-assisted rapid palatal expansion: A review of recent reports

The miniscrew-assisted rapid palatal expander (MARPE) has extended not only skeletal effects with fewer dental changes and but also the age limit of nonsurgical maxillary expansion treatment. Amid its gaining popularity in clinical orthodontics, our current understanding of treatment effectiveness, efficiency, and stability needs to be reassessed. In this review article, the authors have attempted to evaluate MARPE from various aspects with a focus on recent studies.

Dental arch form and interdental widths evaluation in adult Caucasian patients with obstructive sleep apnea syndrome

OBJECTIVE

To evaluate the hypothesis that dental arch form and inter-canine, inter-premolar, and inter-molar widths differ between OSAS patients and non-snoring, non-apneic controls.

METHODS

Dental digital models from 64 OSAS patients and 64 control subjects were used to obtain dental arch forms and to compare them between the two groups. Arch forms were extracted from the lower arch models using a professional graphics program and an orthodontic digital template. Through an orthodontic software, inter-molar, inter-premolar, and inter-canine widths were measured for both upper and lower arches.

RESULTS

The dental arch forms distribution differed between OSAS patients and controls. OSAS patients had reduced inter-canine, inter-premolar, and inter-molar widths for both arches compared to controls.

DISCUSSION

These results suggest that OSAS patients have narrower and more tapered arches than controls. Dental arch morphology and interdental widths differ between OSAS and control groups, supporting the hypothesis that they are an etiological factor.

Effects of Maxillary Skeletal Expansion on Upper Airway Airflow: A Computational Fluid Dynamics Analysis

The effect of maxillary skeletal expansion (MSE) on upper airway in adolescent patients is not clear. The purpose of this study was to determine the upper airway airflow with MSE treatment using computational fluid dynamics analysis. Three-dimensional upper airway finite element models fabricated from cone beam computed tomography images were obtained before and after treatment in an adolescent patient with maxillary constriction. Turbulent analyses were applied. The nasal cavity (NC) was divided into 6 planes along the y-axis and the pharynx was divided into 7 planes in the z-axis. Changes in cross-sectional area, airflow velocity, pressure, and total resistance at maximum expiration and maximum inspiration were determined at each plane after MSE treatment. The greatest increase in area occurred in the oropharynx which was around 40.65%. The average increase in area was 7.42% in the NC and 22.04% in the pharynx. The middle part of pharynx showed the greatest increase of 212.81 mm and 217.99 mm or 36.58% and 40.66%, respectively. During both inspiration and expiration, airflow pressure decreased in both the NC and pharynx, which ranged from -11.34% to -23.68%. In the NC, the average velocity decrease was -0.18 m/s at maximum expiration (ME) and -0.13 m/s at maximum inspiration (MI). In the pharynx, the average velocity decrease was -0.07 m/s for both ME and MI. These results suggest that treatment of maxillary constriction using MSE appliance may show positive effects in improvement of upper airway cross-sectional areas and reduction of upper airway resistance and velocity.

Clustering-based characterization of clinical phenotypes in obstructive sleep apnoea using severity, obesity, and craniofacial pattern

OBJECTIVES

To identify and characterize the phenotypes of adult obstructive sleep apnoea (OSA) patients based on clustering using OSA severity, obesity, and craniofacial pattern.

MATERIAL AND METHODS

The samples consisted of 89 adult OSA patients whose polysomnography and lateral cephalogram were available. With cluster analysis using apneahypopnea index (AHI, events/hour), body mass index (BMI, kg/m2), ANB (degree), and mandibular plane angle (MPA, degree), three clusters were identified. Cephalometric variables including craniofacial, soft palate, hyoid bone, and pharyngeal space compartments were compared among clusters by one-way analysis of variance or Kruskal-Wallis test. Multivariable linear regression analysis was performed to find contributing factors to OSA severity within each cluster.

RESULTS

Cluster-1 (obesity type; 49.4 per cent) exhibited moderate OSA, obesity, and normal sagittal and vertical skeletal pattern (AHI, 22.4; BMI, 25.5; ANB, 3.2 degrees; MPA, 26.3 degrees) without significant upper airway abnormality. Cluster-2 (skeletal type; 33.7 per cent) was characterized by moderate OSA, severe skeletal Class II hyperdivergent pattern with narrow pharyngeal airway spaces, without obesity (AHI, 27.9; BMI, 23.5; ANB, 7.5 degrees; MPA, 36.6 degrees). Cluster-3 (complex type; 16.8 per cent) included severe OSA, obesity, skeletal Class II hyperdivergent pattern (AHI, 52.8; BMI, 28.0; ANB, 4.5 degrees; MPA, 32.2 degrees), with posteriorly displaced hyoid and retroclined soft palate. The main contributing factors to AHI were obesity in Cluster-1; hyperdivergent vertical pattern with narrow pharyngeal space in Cluster-2; and hyperdivergent pattern, obesity, displaced hyoid, and soft palate in Cluster-3.

CONCLUSION

Three OSA phenotypes resulted from this study provide a clinical guideline for differential diagnosis and orthodontic intervention in the interdisciplinary treatment for OSA patients.