腭中缝骨皮质切开辅助快速扩弓对年轻成人的上气道的影响

Evaluating the effect of midpalatal corticotomy-assisted rapid maxillary expansion on the upper airway in young adults using computational fluid dynamics 腭中缝骨皮质切开辅助快速扩弓对年轻成人的上气道的影响 1 equal first-author 2 equal 1 1 3 1 corresp Jun LIN, linjun2@zju.edu.cn Jun LIN, linjun2@zju.edu.cn linjun2@zju.edu.cn https://orcid.org/0000-0003-1587-0853 Department of Stomatology, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou310003, China Department of Stomatology, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou310003, China Department of Stomatology, the First People’s Hospital of Xiaoshan, Hangzhou311200, China Department of Stomatology, the First People’s Hospital of Xiaoshan, Hangzhou311200, China Department of Stomatology, Zhejiang Provincial People’s Hospital (People’s Hospital of Hangzhou Medical College), Hangzhou310014, China Department of Stomatology, Zhejiang Provincial People’s Hospital (People’s Hospital of Hangzhou Medical College), Hangzhou310014, China Midpalatal corticotomy-assisted rapid maxillary expansion (MCRME) is a minimally invasive treatment of maxillary transverse deficiency (MTD) in young adults. However, the effect of MCRME on respiratory function still needs to be determined. In this study, we evaluated the changes in maxillary morphology and the upper airway following MCRME using computational fluid dynamics (CFD). Twenty patients with MTD (8 males, 12 females; mean age 20.55 years) had cone-beam computed tomography (CBCT) images taken before and after MCRME. The CBCT data were used to construct a three-dimensional (3D) upper airway model. The upper airway flow characteristics were simulated using CFD, and measurements were made based on the CBCT images and CFD. The results showed that the widths of the palatal bone and nasal cavity, and the intermolar width were increased significantly after MCRME. The volume of the nasal cavity and nasopharynx increased significantly, while there were no obvious changes in the volumes of the oropharynx and hypopharynx. CFD simulation of the upper airway showed that the pressure drop and maximum velocity of the upper airway decreased significantly after treatment. Our results suggest that in these young adults with MTD, increasing the maxillary width, upper airway volume, and quantity of airflow by MCRME substantially improved upper airway ventilation. 目的 2 采用三维重建技术及流体动力学探究上颌宽度不足的年轻成人经腭中缝骨皮质切开辅助快速扩弓（MCRME）后上颌宽度、上气道形态和功能的变化及治疗效果。 创新点 2 应用三维重建技术及流体动力学评估MCRME对上气道的通气状况的影响 方法 2 本研究选择20例上颌宽度不足年轻成人患者作为研究对象，并分别于矫治前和MCRME治疗三个月后拍摄锥形束CT（CBCT），对其进行三维重建及流体动力学分析，比较矫正前后鼻腔宽度、上颌牙弓宽度、上颌基骨宽度、上气道体积、气流压降和速度的变化。 结论 2 上颌宽度不足的年轻成人采用MCRME矫正后上颌宽度扩大，鼻腔和鼻咽部上气道的体积增加，并且上气道内的气流速度减缓，气流阻力下降，上气道的通气状况整体改善。 Maxillary transverse deficiency (MTD) Rapid maxillary expansion (RME) Upper airway Computational fluid dynamics (CFD) 上颌宽度不足 快速扩弓 上气道 计算流体动力学 1 Introduction 1 Maxillary transverse deficiency (MTD) is a common clinical malocclusion in young adults, characterized mainly by a narrowing of the dental arch, crowded dentition, and negative overjet of the posterior dental region. Due to the high resistance of the mature midpalatal suture, it is not possible to perform ideal sutural separation without surgical osteotomies for expansion ( Leeet al., 2014 Lee et al., 2014 ). Therefore, doctors often use surgically assisted rapid maxillary expansion (SARME) to correct MTD in young adults. The surgical procedure of SARME includes LeFort I osteotomy with or without the pterygomaxillary junction or midline palatal split under general anaesthesia ( Menonet al., 2010 Menon et al., 2010 ). Published reports show that SARME involves potential postoperative risks, such as infection, pain, craniofacial fractures, paresthesia, occasional excess bleeding, sinusitis, and periodontal bone loss ( Derginet al., 2015 Dergin et al., 2015 ; Pereiraet al., 2018 Pereira et al., 2018 ). The surgery also increases the psychological and economic burden for patients. Therefore, in this study we used a minimally invasive method of midpalatal corticotomy-assisted rapid maxillary expansion (MCRME) to correct MTD in young adults. A previous clinical study showed that MCRME was an effective micro-invasive treatment for young adults with MTD ( Wenget al., 2017 Weng et al., 2017 ). Recent studies have found that rapid maxillary expansion (RME) can increase the width and volume of the nasal cavity ( Tausche et al., 2009 Tausche et al., 2009 ; El and Palomo, 2014 El and Palomo, 2014 ; Kim et al., 2018 Kim et al., 2018 ), reduce the resistance of the nasal airflow, and improve the nasal ventilation function ( Warren et al., 1987 Warren et al., 1987 ; Iwasaki et al., 2012 Iwasaki et al., 2012 ; Ghoneima et al., 2015 Ghoneima et al., 2015 ). In a recent review, Buck et al. (2016) Buck et al. (2016) found that SARME could produce substantial short-term volume increases in the nasal cavity of non-growing patients, while evidence rarely showed no effect on oropharyngeal volume. Some scholars have suggested that RME can be used as a treatment option for nasal stenosis caused by nasal septum deformity, nasal infection, allergic rhinitis, and obstructive sleep apnea ( Menegatet al., 2015 Menegat et al., 2015 ; Vinhaet al., 2016 Vinha et al., 2016 ). However, most studies were evaluated as having a high risk of bias. The effect of such volume changes on respiratory function still needs to be determined. Recently, computational fluid dynamics (CFD) has been used for evaluation of airway ventilation ( Iwasakiet al., 2013 Iwasaki et al., 2013 ). Because it can simulate the flow of air and evaluate air current regardless of the shape of the upper airway, we speculated that CFD assessment may be a more accurate method for the complicated evaluation of the upper airway in MTD young adults. In this study, we investigated changes in the maxillary width and upper airway ventilation after MCRME using CFD. 2 Subjects and methods 1 2.1 Subjects 2 This study was approved by the Research Ethics Committee (No. 2019-580-1) of the First Affiliated Hospital of Zhejiang University (Hangzhou, China). A total of 20 consecutive patients with transverse maxillary deficiency underwent MCRME at the Department of Orthodontics from January 2015 to June 2019. The sample comprised 8 male and 12 female subjects with a mean age of (20.55±2.95) years. The inclusion criteria were as follows: (1) according to cone-beam computed tomography (CBCT) measurements (NewTom VGi, Italy; FSV: 110 kV/4.11 mA; SSV: 110 kW/3.00 mA; pixel spacing: 0.300 mm; FOV: full), the difference in width between the mandible and maxilla was more than 5 mm before surgery ( Fig. 1 Fig. 1 ), and the diagnosis was transverse maxillary deficiency; (2) permanent dentition; (3) skeletal maturity (the lateral cephalogram shows at least cervical vertebra stage (Cvs) 4); (4) good periodontal condition; (5) no history of orthodontic or orthognathic treatment; (6) no craniofacial syndrome patients. The exclusion criteria were as follows: (1) congenital maxillofacial deformities; (2) prior orthodontic and surgical treatment on the maxilla; (3) prior maxillary trauma; (4) transverse maxillary deficiency that could be corrected by orthodontic treatment alone; (5) there is a missing or large defect of bilateral maxillary first premolar and first molar. 2.2 Surgical procedures and measurement 2 The surgery was carried out by one oral surgeon using the same surgical techniques. Surgical procedures were as follows ( Weng et al., 2017 Weng et al., 2017 ): a corticotomy in the palate was performed under local anesthesia. The depth was about half of the cortical bone thickness at the midpalatal suture from the incisive canal to the transverse palatine suture ( Fig. 2 Fig. 2 a). A periodontal dressing (Reso-PAC, HAGER WERKEN, Germany) was then applied to prevent infection and promote wound healing ( Fig. 2 Fig. 2 b). One week after surgery, a tooth-borne hyrax maxillary expansion device was attached to the maxillary first premolar and the first molar ( Fig. 2 Fig. 2 c). Each patient was instructed to rotate the device 1/4 turn each morning and evening (each quarter turn was 0.25 mm) for 21 d, then maintain for three months as a passive retainer. CBCT examinations were performed before treatment ( t 1 ) and after three months of retention ( t 2 ). Some landmarks and parameters ( Fig. 3 Fig. 3 ) were measured on the coronal CBCT images at t 1 and t 2 , including the nasal cavity width (NCW), palatal bone width (PBW), and intermolar width (IMW). 2.3 Establishment of the upper airway three-dimensional (3D) model and CFD simulation 2 Two-dimensional tomographic images of computed tomography (CT) scans were imported into Mimics 20.0 software (Materialise Software, Belgium) in digital imaging and communication in medicine (DICOM) format. The CT threshold was adjusted from -1024 to -260, and then the upper airway model was created for the region between the nostrils and the hypopharynx. The frontal sinus, sphenoid sinus, ethmoid sinus, and maxillary sinus were removed by manual editing. After region growth and 3D calculation, a 3D model of the upper airway of the patient was established (Figs. 4 4 a and 4 4 b). In accordance with a recent systematic review ( Guijarro-Martínez and Swennen, 2011 Guijarro-Martínez and Swennen, 2011 ), the upper airway was divided into four parts in the sagittal plane ( Table 1 Table 1 ), and their volumes were measured at t 1 and t 2 . S: sella; PNS: posterior nasal spine; FH: Frankfort plane. Part name Boundary location Nasal cavity Anterior limit: anterior nostrils Posterior limit: line extending from S to the PNS Nasopharynx Superior limit: inferior limit of the nasal cavity Inferior limit: plane parallel to the FH plane passing through PNS Oropharynx Superior limit: inferior limit of the nasopharynx Inferior limit: plane parallel to the FH plane passing through the superior margin of the epiglottis Hypopharynx Superior limit: inferior limit of the oropharynx Inferior limit: plane parallel to the FH plane that passes through the most anteroinferior point of the 4th cervical vertebra The 3D model was imported into ANSYS 19.0 software (ANSYS, Inc., USA) in signal temporal logic (STL) format for meshing and boundary condition setting ( Qianet al., 2013 Qian et al . , 2013 ). The bilateral nostrils were set as velocity inlets, the volumetric flow rate was 275 mL/s, the hypopharynx plane was set at a static pressure of 0 Pa as the outlet, and standard atmospheric pressure was applied. The standard κ - ε two-equation turbulence model was used to simulate the airflow field of the upper airway. This model was chosen because of its robustness, economy, and reasonable prediction of flow ( Chang et al., 2018 Chang et al., 2018 ). The walls of the model, which were assumed to be rigid and noncompliant, were set at no-slip conditions, and simulations were carried out for 1000 times to calculate mean values. The pressure drop and maximum airflow velocity of the upper airway were recorded and assessed at t 1 and t 2 ( Fig. 4 Fig. 4 c). 2.4 Statistical analysis 2 The means and standard deviations (mean±SD) of the measurements were calculated, and paired t -tests were performed on the maxillary width and relevant indicators of airflow characteristics during the t 1 and t 2 periods, using the SPSS software package (SPSS 23.0, IBM, USA). For all tests, P < 0.05 was considered statistically significant. 3 Results 1 3.1 Widths of the maxillary and nasal cavities 2 Twenty patients achieved a significant transverse width expansion after MCRME. The IMW and PBW at the first molar and first premolar level exhibited significant increases ( P < 0.01). The width between the lateral walls of the nasal cavity was also expanded significantly ( P < 0.01; Table 2 Table 2 ). The data are expressed as mean±standard deviation ( n =20). PBW6 and PBW4: palatal bone widths at the first premolar and first molar regions, respectively; IMW6 and IMW4: intermolar widths at the first premolar and first molar regions, respectively; NCW6 and NCW4: nasal cavity lateral wall widths at the first premolar and first molar regions, respectively. ** P < 0.01. 2 Position 2 Width (mm) 2 D -value Before treatment After treatment PBW6 30.6±4.5 33.0±4.8 2.3±1.6 ** IMW6 41.5±4.0 47.0±3.9 5.5±3.1 ** NCW6 34.4±2.9 35.7±3.0 1.4±0.9 ** PBW4 22.5±4.7 25.4±4.6 2.9±2.3 ** IMW4 32.1±2.8 38.2±2.7 6.1±3.3 ** NCW4 29.5±4.0 31.3±4.0 1.7±1.5 ** 3.2 Upper airway volume 2 The total volume of the upper airway increased ( P < 0.01). In particular, there was a highly significant increase in the volumes of the nasal cavity and nasopharynx ( P < 0.01). No significant changes were found in the volumes of the oropharyngeal or hypopharynx airways after treatment ( P > 0.05; Table 3 Table 3 ). The data are expressed as mean±standard deviation ( n =20). ** P < 0.01. 2 Position 2 Volume (cm 3 ) 2 D -value Before treatment After treatment Nasal cavity 16.29±3.33 18.24±3.61 1.95±1.68 ** Nasopharynx 6.44±1.83 7.19±1.68 0.76±0.68 ** Oropharynx 17.59±3.93 17.38±4.56 -0.21±2.51 Laryngopharynx 8.03±3.70 7.93±3.66 -0.09±1.41 Upper airway 48.35±9.53 50.75±9.92 2.40±4.07 ** 3.3 Upper airway ventilation 2 The CFD results of upper airway pressure and velocity before and after MCRME are shown in Tables 4 4 and 5 5 , respectively. The pressure drop and maximum velocity in the nasal cavity and nasopharynx decreased significantly after treatment ( P < 0.01). The pressure drop and maximum velocity in the oropharynx and hypopharynx also decreased after treatment ( P < 0.05). Figs. 5 5 and 6 6 show typical examples of the maximum velocities and pressures of the nasal cavity, nasopharynx, oropharynx, and hypopharynx before and after MCRME. The data are expressed as mean±standard deviation ( n =20). * P < 0.05; ** P < 0.01. 2 Position 2 Pressure drop (Pa) 2 D -value Before treatment After treatment Nasal cavity 23.99±11.83 13.08±7.42 -10.91±8.93 ** Nasopharynx 11.19±7.21 5.64±3.38 -5.55±6.00 ** Oropharynx 4.24±1.82 3.27±1.63 -0.98±1.72 * Laryngopharynx 2.92±2.11 1.96±1.96 -0.95±2.02 * 1;2;3;4; 1;2;3;4; The data are expressed as mean±standard deviation ( n =20). * P < 0.05; ** P < 0.01. 2 Position 2 Velocity (m/s) 2 D -value Before treatment After treatment Nasal cavity 5.23±1.09 3.99±0.84 -1.24±0.92 ** Nasopharynx 3.81±0.88 2.81±0.88 -1.00±0.89 ** Oropharynx 2.55±0.57 2.14±0.64 -0.41±0.72 * Laryngopharynx 2.07±0.52 1.71±0.64 -0.36±0.62 * 4 Discussion 1 Correction of MTD is more challenging for patients with a mature maxilla. SARME has gradually gained popularity as a treatment option to correct MTD in young adults. Commonly used surgical procedures include separation of the midpalatal suture, separation of the pterygomaxillary sutures, and LeFort I corticotomy. The purpose of these procedures is to remove the resistance of the midface to lateral expansion. Lee et al. (2014) Lee et al. (2014) performed finite element analysis on these three surgical models and showed that they produced similar amounts of stress and displacement along the teeth, midpalatal sutures, and craniofacial sutures. Therefore, they recommended midpalatal suture separation to complement the use of a bone-borne rapid maxillary expander in adults, which requires minimal surgical intervention. Sant'Ana et al. (2016) Sant'Ana et al. (2016) compared surgically assisted RME with and without a midpalatal split and showed that without a midpalatal split, patients suffered greater discomfort. Therefore, in our study we used midpalatal corticotomy to assist RME. As a result, a good expansion effect was achieved in 20 cases in our study. The data suggest that the maxillary width had increased significantly after maxillary expansion. The distance increases at the first premolars (6.1 mm) and the first molars (5.5 mm) were consistent with those of other studies ( Kartalian et al., 2010 Kartalian et al., 2010 ; Chang et al., 2013 Chang et al., 2013 ). However, the average transverse expansion of 2.9 and 2.3 mm of the PBW was smaller than those of a previous study after rapid palatal expansion (4.4 and 3.9 mm, respectively) ( Zandi et al., 2014 Zandi et al., 2014 ). The reason may be that Zandi et al. (2014) Zandi et al. (2014) performed osteotomy of the lateral maxillary wall from the piriform rim to the pterygomaxillary junction, and midline osteotomy between the central incisors and the pterygomaxillary disjunction, and released more resistance. The percentile increase ((level after RME/level before RME-1)×100%) at the first premolar level (average, 13.03%) was greater than that at the first molar level (average, 7.57%), as in a previous study ( Seeberger et al., 2015 Seeberger et al., 2015 ). This indicates a V-shaped opening from anterior to posterior due to the mainly posterior resistance of the maxilla. Figueiredo et al. (2016) Figueiredo et al. (2016) found bone expansion of up to 48% in children with RME. In this paper, the amount of palatal bone in the first molar region accounted for 43% of the increase. This result suggests that by using MCRME, young adults can have expansion effects similar to those of children treated with RME. Previous studies that used acoustic rhinometry to assess the airway reported an increase in nasal volume. Babacan et al. (2006) Babacan et al. (2006) and Wriedt et al. (2001) Wriedt et al. (2001) found that nasal airway volume increased by 14.09% and 21.20%, respectively. In a long-term study, Seeberger et al. (2010) Seeberger et al . (2010) found that nasal volume increased by 23.25% at 63 months after expansion. Recent studies which used CBCT and 3D model reconstruction reported a smaller increase in nasal cavity volume than that shown by acoustic rhinometry. Deeb et al. (2010) Deeb et al . (2010) reported only a 5.1% increase in the nasal airway in bone-borne expansion using CT examination. Nada et al. (2013) Nada et al . (2013) found the nasal airway of a tooth-borne SARME group increased by 9.7%. Our result, that the nasal cavity volume increased by 12.0%, was consistent with previous studies. Our finding that the oropharynx and hypopharynx volumes did not change much was in agreement with the results of previous studies ( Smith et al., 2012 Smith et al . , 2012 ; Pereira-Filhoet al., 2014 Pereira-Filho et al . , 2014 ). This indicates that MCRME may not influence the lower airway significantly. However, Liu et al. (2019) Liu et al . (2019) found a significant increase in the oropharynx airway after surgically assisted rapid palatal expansion (SARPE) combined with surgically facilitated orthodontic therapy (SFOT), and some studies ( Zhaoet al., 2010 Zhao et al . , 2010 ; Aloufi et al., 2012 Aloufi et al . , 2012 ) found a significant increase in the retropalatal space. The main reasons for this discrepancy may be the difference in the measurement method and the boundary of the upper airway. Our study used CFD to evaluate airway ventilation before and after treatment. Our results showed that the pressure drop and maximum velocity of the nasal cavity and nasopharynx were decreased after treatment ( P < 0.01). These results confirm those of previous studies ( Iwasaki et al., 2012 Iwasaki et al . , 2012 , 2014 2014 ; Ghoneima et al., 2015 Ghoneima et al . , 2015 ) which investigated upper airway airflow characteristics by CFD, indicating that the nasal airflow was more gradual after treatment. Iwasakiet al. (2019) Iwasaki et al . (2019) evaluated pharyngeal airway pressure during inspiration in young adolescents using CFD and found that the pharyngeal airway pressure was decreased with the significant reduction in nasal resistance following RME. Our results also showed that the pharyngeal airway velocity and pressure drop decreased. The reason for this may be that after the MCRME relieves the nasal resistance, the pressure of the pharyngeal airway also decreases, easing constriction in the pharyngeal airway and reducing pharyngeal airflow resistance. Some scholars believe that MTD plays an important role in the pathophysiology of obstructive sleep apnea, because it is associated with low tongue posture, which may lead to narrowing of the oropharyngeal airway ( Chang et al., 2013 Chang et al . , 2013 ). MTD can also cause nasal obstruction, which in turn triggers obstructive sleep apnea syndrome (OSAS), because the negative pressure of the pharyngeal airway increases as the pharyngeal airway shrinks ( Iwasaki et al., 2012 Iwasaki et al . , 2012 ). Our results suggest that MCRME in young adults can reduce the upper airway pressure and relieve the resistance of the upper airway. However, the functional benefit of SARME to the airway has not been fully determined ( Neeleyet al., 2007 Neeley et al . , 2007 ). Vinha et al. (2016) Vinha et al . (2016) reported that OSAS symptoms are relieved after RME. Magnusson et al. (2011) Magnusson et al . (2011) reported that a subjective improvement in nasal function was significantly improved only in patients with an initial nasal obstruction. In addition, they found no correlation between the objective volume increase of the nasal cavity and the subjective perception of nasal function improvement. Thus, one limitation of the study was the absence of physical measurements to compare with CFD-derived values and to determine differences in the effects after treatment. Another limitation was that the three-month follow-up time was not enough. Smith et al. (2012) Smith et al . (2012) found that the volume increase was related to the length of the follow-up: at the first evaluation, the volume increased, but it then relapsed and the gain was lost. 5 Conclusions 1 The use of MCRME in the correction of maxillary deficiency in these adult patients improved both the maxillary width and upper airway volume, and reduced the upper airway pressure and velocity. In short, MCRME is a minimally invasive and effective treatment for MTD in adults and is useful for improving upper airway ventilation. References Aloufi F , Preston CB , Zawawi KH , 2012 . Changes in the upper and lower pharyngeal airway spaces associated with rapid maxillary expansion . ISRN Dent , 2012 : 290964 . https://doi.org/10.5402/2012/290964 https://doi.org/10.5402/2012/290964 Changes in the upper and lower pharyngeal airway spaces associated with rapid maxillary expansion Babacan H , Sokucu O , Doruk C , et al. , 2006 . Rapid maxillary expansion and surgically assisted rapid maxillary expansion effects on nasal volume . Angle Orthod , 76 ( 1 ): 66 - 71 . https://doi.org/10.1043/0003-3219(2006)076[0066:RMEASA]2.0.CO;2 https://doi.org/10.1043/0003-3219(2006)076[0066:RMEASA]2.0.CO;2 Rapid maxillary expansion and surgically assisted rapid maxillary expansion effects on nasal volume Buck LM , Dalci O , Darendeliler MA , et al. , 2016 . Effect of surgically assisted rapid maxillary expansion on upper airway volume: a systematic review . J Oral Maxillofac Surg , 74 ( 5 ): 1025 - 1043 . https://doi.org/10.1016/j.joms.2015.11.035 https://doi.org/10.1016/j.joms.2015.11.035 Effect of surgically assisted rapid maxillary expansion on upper airway volume: a systematic review Chang KK , Kim KB , McQuilling MW , et al. , 2018 . Fluid structure interaction simulations of the upper airway in obstructive sleep apnea patients before and after maxillomandibular advancement surgery . Am J Orthod Dentofacial Orthop , 153 ( 6 ): 895 - 904 . https://doi.org/10.1016/j.ajodo.2017.08.027 https://doi.org/10.1016/j.ajodo.2017.08.027 Fluid structure interaction simulations of the upper airway in obstructive sleep apnea patients before and after maxillomandibular advancement surgery Chang Y , Koenig LJ , Pruszynski JE , et al. , 2013 . Dimensional changes of upper airway after rapid maxillary expansion: a prospective cone-beam computed tomography study . Am J Orthod Dentofacial Orthop , 143 ( 4 ): 462 - 470 . https://doi.org/10.1016/j.ajodo.2012.11.019 https://doi.org/10.1016/j.ajodo.2012.11.019 Dimensional changes of upper airway after rapid maxillary expansion: a prospective cone-beam computed tomography study Deeb W , Hansen L , Hotan T , et al. , 2010 . Changes in nasal volume after surgically assisted bone-borne rapid maxillary expansion . Am J Orthod Dentofacial Orthop , 137 ( 6 ): 782 - 789 . https://doi.org/10.1016/j.ajodo.2009.03.042 https://doi.org/10.1016/j.ajodo.2009.03.042 Changes in nasal volume after surgically assisted bone-borne rapid maxillary expansion Dergin G , Aktop S , Varol A , et al. , 2015 . Complications related to surgically assisted rapid palatal expansion . Oral Surg Oral Mol Oral Pathol Oral Radiol , 119 ( 6 ): 601 - 607 . https://doi.org/10.1016/j.oooo.2015.01.008 https://doi.org/10.1016/j.oooo.2015.01.008 Complications related to surgically assisted rapid palatal expansion El H , Palomo JM , 2014 . Three-dimensional evaluation of upper airway following rapid maxillary expansion: a CBCT study . Angle Orthod , 84 ( 2 ): 265 - 273 . https://doi.org/10.2319/012313-71.1 https://doi.org/10.2319/012313-71.1 Three-dimensional evaluation of upper airway following rapid maxillary expansion: a CBCT study Figueiredo DSF , Cardinal L , Bartolomeo FUC , et al. , 2016 . Effects of rapid maxillary expansion in cleft patients resulting from the use of two different expanders . Dental Press J Orthod , 21 ( 6 ): 82 - 90 . https://doi.org/10.1590/2177-6709.2016-001.aop https://doi.org/10.1590/2177-6709.2016-001.aop Effects of rapid maxillary expansion in cleft patients resulting from the use of two different expanders Ghoneima A , AlBarakati S , Jiang FF , et al. , 2015 . Computational fluid dynamics analysis of the upper airway after rapid maxillary expansion: a case report . Prog Orthod , 16 : 10 . https://doi.org/10.1186/s40510-015-0085-x https://doi.org/10.1186/s40510-015-0085-x Computational fluid dynamics analysis of the upper airway after rapid maxillary expansion: a case report Guijarro-Martínez R , Swennen GRJ , 2011 . Cone-beam computerized tomography imaging and analysis of the upper airway: a systematic review of the literature . Int J Oral Maxillofac Surg , 40 ( 11 ): 1227 - 1237 . https://doi.org/10.1016/j.ijom.2011.06.017 https://doi.org/10.1016/j.ijom.2011.06.017 Cone-beam computerized tomography imaging and analysis of the upper airway: a systematic review of the literature Iwasaki T , Saitoh I , Takemoto Y , et al. , 2012 . Improvement of nasal airway ventilation after rapid maxillary expansion evaluated with computational fluid dynamics . Am J Orthod Dentofacial Orthop , 141 ( 3 ): 269 - 278 . https://doi.org/10.1016/j.ajodo.2011.08.025 https://doi.org/10.1016/j.ajodo.2011.08.025 Improvement of nasal airway ventilation after rapid maxillary expansion evaluated with computational fluid dynamics Iwasaki T , Saitoh I , Takemoto Y , et al. , 2013 . Tongue posture improvement and pharyngeal airway enlargement as secondary effects of rapid maxillary expansion: a cone-beam computed tomography study . Am J Orthod Dentofacial Orthop , 143 ( 2 ): 235 - 245 . https://doi.org/10.1016/j.ajodo.2012.09.014 https://doi.org/10.1016/j.ajodo.2012.09.014 Tongue posture improvement and pharyngeal airway enlargement as secondary effects of rapid maxillary expansion: a cone-beam computed tomography study Iwasaki T , Takemoto Y , Inada E , et al. , 2014 . The effect of rapid maxillary expansion on pharyngeal airway pressure during inspiration evaluated using computational fluid dynamics . Int J Pediatr Otorhinolaryngol , 78 ( 8 ): 1258 - 1264 . https://doi.org/10.1016/j.ijporl.2014.05.004 https://doi.org/10.1016/j.ijporl.2014.05.004 The effect of rapid maxillary expansion on pharyngeal airway pressure during inspiration evaluated using computational fluid dynamics Iwasaki T , Yanagisawa-Minami A , Suga H , et al. , 2019 . Rapid maxillary expansion effects of nasal airway in children with cleft lip and palate using computational fluid dynamics . Orthod Craniofac Res , 22 ( 3 ): 201 - 207 . https://doi.org/10.1111/ocr.12311 https://doi.org/10.1111/ocr.12311 Rapid maxillary expansion effects of nasal airway in children with cleft lip and palate using computational fluid dynamics Kartalian A , Gohl E , Adamian M , et al. , 2010 . Cone-beam computerized tomography evaluation of the maxillary dentoskeletal complex after rapid palatal expansion . Am J Orthod Dentofacial Orthop , 138 ( 4 ): 486 - 492 . https://doi.org/10.1016/j.ajodo.2008.10.025 https://doi.org/10.1016/j.ajodo.2008.10.025 Cone-beam computerized tomography evaluation of the maxillary dentoskeletal complex after rapid palatal expansion Kim SY , Park YC , Lee KJ , et al. , 2018 . Assessment of changes in the nasal airway after nonsurgical miniscrew-assisted rapid maxillary expansion in young adults . Angle Orthod , 88 ( 4 ): 435 - 441 . https://doi.org/10.2319/092917-656.1 https://doi.org/10.2319/092917-656.1 Assessment of changes in the nasal airway after nonsurgical miniscrew-assisted rapid maxillary expansion in young adults Lee SC , Park JH , Bayome M , et al. , 2014 . Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis . Am J Orthod Dentofacial Orthop , 145 ( 5 ): 638 - 648 . https://doi.org/10.1016/j.ajodo.2013.12.029 https://doi.org/10.1016/j.ajodo.2013.12.029 Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis Liu PP , Jiao DL , Wang XY , et al. , 2019 . Changes in maxillary width and upper airway spaces in young adults after surgically assisted rapid palatal expansion with surgically facilitated orthodontic therapy . Oral Surg Oral Med Oral Pathol Oral Radiol , 127 ( 5 ): 381 - 386 . https://doi.org/10.1016/j.oooo.2018.11.005 https://doi.org/10.1016/j.oooo.2018.11.005 Changes in maxillary width and upper airway spaces in young adults after surgically assisted rapid palatal expansion with surgically facilitated orthodontic therapy Magnusson A , Bjerklin K , Nilsson P , et al. , 2011 . Nasal cavity size, airway resistance, and subjective sensation after surgically assisted rapid maxillary expansion: a prospective longitudinal study . Am J Orthod Dentofacial Orthop , 140 ( 5 ): 641 - 651 . https://doi.org/10.1016/j.ajodo.2010.11.024 https://doi.org/10.1016/j.ajodo.2010.11.024 Nasal cavity size, airway resistance, and subjective sensation after surgically assisted rapid maxillary expansion: a prospective longitudinal study Menegat F , Monnazzi MS , Silva BN , et al. , 2015 . Assessment of nasal obstruction symptoms using the NOSE scale after surgically assisted rapid maxillary expansion . Int J Oral Maxillofac Surg , 44 ( 11 ): 1346 - 1350 . https://doi.org/10.1016/j.ijom.2015.06.018 https://doi.org/10.1016/j.ijom.2015.06.018 Assessment of nasal obstruction symptoms using the NOSE scale after surgically assisted rapid maxillary expansion Menon S , Manerikar R , Sinha R , 2010 . Surgical management of transverse maxillary deficiency in adults . J Maxillofac Oral Surg , 9 ( 3 ): 241 - 246 . https://doi.org/10.1007/s12663-010-0034-7 https://doi.org/10.1007/s12663-010-0034-7 Surgical management of transverse maxillary deficiency in adults Nada RM , van Loon B , Schols JGJH , et al. , 2013 . Volumetric changes of the nose and nasal airway 2 years after tooth-borne and bone-borne surgically assisted rapid maxillary expansion . Eur J Oral Sci , 121 ( 5 ): 450 - 456 . https://doi.org/10.1111/eos.12068 https://doi.org/10.1111/eos.12068 Volumetric changes of the nose and nasal airway 2 years after tooth-borne and bone-borne surgically assisted rapid maxillary expansion Neeley WW , Edgin WA , Gonzales DA , 2007 . A review of the effects of expansion of the nasal base on nasal airflow and resistance . J Maxillofac Oral Surg , 65 ( 6 ): 1174 - 119 . https://doi.org/10.1016/j.joms.2006.06.295 https://doi.org/10.1016/j.joms.2006.06.295 A review of the effects of expansion of the nasal base on nasal airflow and resistance Pereira MD , Koga AF , Prado GPR , et al. , 2018 . Complications from surgically assisted rapid maxillary expansion with HAAS and HYRAX expanders . J Craniofac Surg , 29 ( 2 ): 275 - 278 . https://doi.org/10.1097/SCS.0000000000004079 https://doi.org/10.1097/SCS.0000000000004079 Complications from surgically assisted rapid maxillary expansion with HAAS and HYRAX expanders Pereira-Filho VA , Monnazzi MS , Gabrielli MAC , et al. , 2014 . Volumetric upper airway assessment in patients with transverse maxillary deficiency after surgically assisted rapid maxillary expansion . Int J Oral Maxillofac Surg , 43 ( 5 ): 581 - 586 . https://doi.org/10.1016/j.ijom.2013.11.002 https://doi.org/10.1016/j.ijom.2013.11.002 Volumetric upper airway assessment in patients with transverse maxillary deficiency after surgically assisted rapid maxillary expansion Qian YM , Qian HX , Wu YD , et al. , 2013 . Numeric simulation of the upper airway structure and airflow dynamic characteristics after unilateral complete maxillary resection . Int J Prosthodont , 26 ( 3 ): 268 - 271 . https://doi.org/10.11607/ijp.2970 https://doi.org/10.11607/ijp.2970 Numeric simulation of the upper airway structure and airflow dynamic characteristics after unilateral complete maxillary resection Sant'Ana LFM , Pinzan-Vercelino CRM , Gurgel JA , et al. , 2016 . Evaluation of surgically assisted rapid maxillary expansion with and without midpalatal split . Int J Oral Maxillofac Surg , 45 ( 8 ): 997 - 1001 . https://doi.org/10.1016/j.ijom.2016.03.005 https://doi.org/10.1016/j.ijom.2016.03.005 Evaluation of surgically assisted rapid maxillary expansion with and without midpalatal split Seeberger R , Kater W , Davids R , et al. , 2010 . Long term effects of surgically assisted rapid maxillary expansion without performing osteotomy of the pterygoid plates . J Cranio Maxill Surg , 38 ( 3 ): 175 - 178 . https://doi.org/10.1016/j.jcms.2009.07.003 https://doi.org/10.1016/j.jcms.2009.07.003 Long term effects of surgically assisted rapid maxillary expansion without performing osteotomy of the pterygoid plates Seeberger R , Gander E , Hoffmann J , et al. , 2015 . Surgical management of cross-bites in orthognathic surgery: surgically assisted rapid maxillary expansion (SARME) versus two-piece maxilla . J Cranio Maxill Surg , 43 ( 7 ): 1109 - 1112 . https://doi.org/10.1016/j.jcms.2015.05.012 https://doi.org/10.1016/j.jcms.2015.05.012 Surgical management of cross-bites in orthognathic surgery: surgically assisted rapid maxillary expansion (SARME) versus two-piece maxilla Smith T , Ghoneima A , Stewart K , et al. , 2012 . Three-dimensional computed tomography analysis of airway volume changes after rapid maxillary expansion . Am J Orthod Dentofacial Orthop , 141 ( 5 ): 618 - 626 . https://doi.org/10.1016/j.ajodo.2011.12.017 https://doi.org/10.1016/j.ajodo.2011.12.017 Three-dimensional computed tomography analysis of airway volume changes after rapid maxillary expansion Tausche E , Deeb W , Hansen L , et al. , 2009 . CT analysis of nasal volume changes after surgically-assisted rapid maxillary expansion . J Orofac Orthop , 70 ( 4 ): 306 - 317 . https://doi.org/10.1007/s00056-009-9910-5 https://doi.org/10.1007/s00056-009-9910-5 CT analysis of nasal volume changes after surgically-assisted rapid maxillary expansion Vinha PP , Eckeli AL , Faria AC , et al. , 2016 . Effects of surgically assisted rapid maxillary expansion on obstructive sleep apnea and daytime sleepiness . Sleep Breath , 20 ( 2 ): 501 - 508 . https://doi.org/10.1007/s11325-015-1214-y https://doi.org/10.1007/s11325-015-1214-y Effects of surgically assisted rapid maxillary expansion on obstructive sleep apnea and daytime sleepiness Warren DW , Hershey G , Turvey TA , et al. , 1987 . The nasal airway following maxillary expansion . Am J Orthod Dentofacial Orthop , 91 ( 2 ): 111 - 116 . https://doi.org/10.1016/0889-5406(87)90467-7 https://doi.org/10.1016/0889-5406(87)90467-7 The nasal airway following maxillary expansion Weng LX , Song XJ , Li J , et al. , 2017 . Midpalatal cortex osteotomy assisted rapid maxillary expansion for correction of maxillary transverse deficiency in young adults . J Zhejiang Univ Med Sci , 46 ( 2 ): 198 - 205 (in Chinese) . https://doi.org/10.3785/j.issn.1008-9292.2017.04.13 https://doi.org/10.3785/j.issn.1008-9292.2017.04.13 Midpalatal cortex osteotomy assisted rapid maxillary expansion for correction of maxillary transverse deficiency in young adults Wriedt S , Kunkel M , Zentner A , et al. , 2001 . Surgically assisted rapid palatal expansion an acoustic rhinometric, morphometric and sonographic investigation . J Orofac Orthop , 62 ( 2 ): 107 - 115 . https://doi.org/10.1007/pl00001921 https://doi.org/10.1007/pl00001921 Surgically assisted rapid palatal expansion an acoustic rhinometric, morphometric and sonographic investigation Zandi M , Miresmaeili A , Heidari A , 2014 . Short-term skeletal and dental changes following bone-borne versus tooth-borne surgically assisted rapid maxillary expansion: a randomized clinical trial study . J Cranio Maxill Surg , 42 ( 7 ): 1190 - 1195 . https://doi.org/10.1016/j.jcms.2014.02.007 https://doi.org/10.1016/j.jcms.2014.02.007 Short-term skeletal and dental changes following bone-borne versus tooth-borne surgically assisted rapid maxillary expansion: a randomized clinical trial study Zhao Y , Nguyen M , Gohl E , et al. , 2010 . Oropharyngeal airway changes after rapid palatal expansion evaluated with cone-beam computed tomography . Am J Orthod Dentofacial Orthop , 137 ( 4 Suppl ): S71 - S78 . https://doi.org/10.1016/j.ajodo.2008.08.026 https://doi.org/10.1016/j.ajodo.2008.08.026 Oropharyngeal airway changes after rapid palatal expansion evaluated with cone-beam computed tomography Juan LI designed the study. Lingfang SHI collected the data. Xiayao ZHANG, Luxi WENG, and Hong CHEN performed the data processing and data analysis. Juan LI, Lingfang SHI, and Jun LIN wrote and edited the manuscript. All authors have edited and approved the final manuscript, and they have full access to all the data in the study and take responsibility for the integrity and security of the data. The research is supported by the National Natural Science Foundation of China (No. 81970978), the Zhejiang Provincial Natural Science Foundation of China (No. LQ18H140004), and the Zhejiang Provincial Medical Health & Hygienic Science and Technology Project of China (Nos. 2018KY365, 2019RC156, and 2020KY449). 10.1631/jzus.B2000090 1673-1581（2021）02-0146-10 LI Juan,SHI Lingfang,ZHANG Xiayao et al., 2021. Evaluating the effect of midpalatal corticotomy-assisted rapid maxillary expansion on the upper airway in young adults using computational fluid dynamics. Journal of Zhejiang University-SCIENCE B(Biomedicine & Biotechnology), 22(2):146-155. LI Juan,SHI Lingfang,ZHANG Xiayao et al., 2021. Evaluating the effect of midpalatal corticotomy-assisted rapid maxillary expansion on the upper airway in young adults using computational fluid dynamics. Journal of Zhejiang University-SCIENCE B(Biomedicine & Biotechnology), 22(2):146-155. 2020-03-09 2020-10-12 2021-02-15 2022-05-09 © Zhejiang University Press 2021 Juan LI, Lingfang SHI, Xiayao ZHANG, Luxi WENG, Hong CHEN, and Jun LIN declare that they have no conflict of interest. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5). Informed consent was obtained from all patients for being included in the study. Additional informed consent was obtained from all patients for which identifying information is included in this article. Compliance with ethics guidelines 浙江大学学报（英文版）（B辑：生物医学和生物技术） 2 22