Rapid maxillary expansion effects of nasal airway in children with cleft lip and palate using computational fluid dynamics

Changes in upper airway airflow after rapid maxillary expansion considering normal craniofacial development as a factor: a retrospective study using computer fluid dynamics

Background/Objectives

Evidence suggests nasal airflow resistance reduces after rapid maxillary expansion (RME). However, the medium-term effects of RME on upper airway (UA) airflow characteristics when normal craniofacial development is considered are still unclear. This retrospective cohort study used computer fluid dynamics (CFD) to evaluate the medium-term changes in the UA airflow (pressure and velocity) after RME in two distinct age-based cohorts.

Materials/Methods

The study included 48 subjects who underwent RME divided into two cohorts: a 6−9-year-old group (EEG group: early expansion group − 25 subjects) and an 11−14-year-old group (LEG group: late expansion group − 23 subjects). The nasal cavity and pharyngeal anatomy were segmented from Cone-beam computed tomography reconstructions taken before RME (T0) and 12 after RME (T1). The two UA airflow variables (pressure and velocity) were simulated using CFD. The maxillary expansion (PW) amount, two cross-sectional area measurements (CS1 = anterior cross-section and CS2 = posterior cross-section), and four UAs’ subregions (NC = nasal cavity, PAtotal = pharyngeal airway, NP = nasopharynx, VP = velopharynx, and OP = Oropharynx) were also considered. All data were statistically analyzed.

Results

At the baseline, the airflow pressure, velocity, and noted obstructions were significantly higher in the EEG compared to LEG. At T1, there was a significant improvement in the median airway parameters in both groups, which was remarkably greater in the EEG. A significant negative correlation was found between pressure/velocity and both CS2 and NP. According to the CFD plots, the airflow pressure and velocity changes could be attributed to the reduction of the adenotonsillar tissues’ sizes, which were remarkably more marked in the EEG.

Limitations

The results of this study cannot be generalized since they referred to a retrospective orthodontic sample without obstructive adenotonsillar hypertrophy.

Conclusions/Implications

Twelve months after RME, normal craniofacial developmental changes and spontaneous adenotonsillar tissues volume regression could represent the most significant factors influencing UA airflow changes.

Nasal Airflow Dynamics following LeFort I Advancement in Cleft Nasal Deformities: A Retrospective Preliminary Study

Unilateral cleft lip and palate (UCLP) nasal deformity impacts airflow patterns and pressure distribution, leading to nasal breathing difficulties. This study aims to create an integrated approach using computer-aided design (CAD) and computational fluid dynamics (CFD) to simulate airway function and assess outcomes in nasal deformities associated with unilateral cleft lip and palate (UCLP) after LeFort I osteotomy advancement. Significant alterations were observed in nasal geometry, airflow velocity, pressure dynamics, volumetric flow rate, and nasal resistance postoperatively, indicating improved nasal airflow. The cross-sectional area increased by 26.6%, airflow rate by 6.53%, and nasal resistance decreased by 6.23%. The study offers quantitative insights into the functional impacts of such surgical interventions, contributing to a deeper understanding of UCLP nasal deformity treatment and providing objective metrics for assessing surgical outcome.

Nasal Airway Volumes are More Asymmetric in Skeletally Mature Patients With Cleft lip and Palate Than Controls on 3-Dimensional Analysis

BACKGROUND

This study assesses nasal airway volumes in skeletally mature patients with CLP and healthy controls and examines the relationship among nasal volumes, cleft laterality, and facial asymmetry.

METHODS

Computed tomography images from patients with CLP and controls were analyzed using Mimics Version 23.0 (Materialise, Leuven, Belgium). Relationships among nasal airway volume, cleft laterality, and facial asymmetry were compared.

RESULTS

The 89 patients in this study included 66 (74%) CLP and 23 (17%) controls. Nasal airway volumes in CLP were more asymmetric than controls (26.8±17.5% vs. 17.2±14.4%; P=0.015). In UCLP, the smaller nasal airway was on the cleft side 81% of the time (P<0.001). Maximum airway stenosis was on the cleft side 79% of the time (P<0.001), and maximum stenosis was on the same side as the smaller airway 89% of the time (P<0.001). There was a mild linear relationship between nasal airway asymmetry and maximum stenosis (r=0.247, P=0.023). On 3-dimensional image reconstruction, the septum often bowed convexly into the cleft-sided nasal airway with a caudal deviation towards the noncleft side. Nasal airway asymmetry was not associated with facial midline asymmetry (P>0.05).

CONCLUSION

The nasal airway is more asymmetric in patients with cleft lip and palate compared with the general population, with the area of maximum stenosis usually occurring on the cleft-sided airway. In patients with unilateral cleft lip and palate, the septum often bows into the cleft side, reducing the size of that nasal airway. Nasal airway asymmetry did not correlate with facial asymmetry.

Impact of palatopharyngeal sizes changing on pharyngeal airflow fluctuation and airway vibration in a pediatric airway

Snoring is common in children and is associated with many adverse consequences. One must study the relationships between pharyngeal morphology and snoring physics to understand snoring progression. Although some model studies have provided fluid-structure interaction dynamic descriptions for the correlation between airway size and snoring physics, the descriptions still need to be further investigated in patient-specific airway models. Fluid-structure interaction studies using patient-specific airway structures complement the above model studies. Based on reported cephalometric measurement methods, this study quantified and preset the size of the palatopharynx airway in a patient-specific airway and investigated how the palatopharynx size affects the pharyngeal airflow fluctuation, soft palate vibration, and glossopharynx vibration with the help of a verified FSI method. The results showed that the stenosis anterior airway of the soft palate increased airway resistance and airway resistance fluctuations, which can lead to increased sleep effort and frequent snoring. Widening of the anterior airway can reduce airflow resistance and avoid obstructing the anterior airway by the soft palate vibration. The pharyngeal airflow resistance, mouth inflow proportion, and soft palate apex displacement have components at the same frequencies in all airway models, and the glossopharynx vibration and instantaneous inflow rate have components at the same frequencies, too. The mechanism of this same frequency fluctuation phenomenon can be explained by the fluid-structure interaction dynamics of an ideal coupled model consisting of a flexible plate model and a collapsible tube model. The results of this study demonstrate the potential of FSI in studying snoring physics and clarify to some degree the mechanism of airway morphology affecting airway vibration physics.

Does Differential Maxillary Expansion Prior to Alveolar Cleft Bone Grafting Affect Nasal Width?

OBJECTIVE

Determine the effects of differential maxillary expansion on nasal width in patients with unilateral cleft lip and alveolus with or without cleft of the secondary palate (UCLA ± P).

DESIGN

Retrospective radiographic study.

SETTING

Institutional.

PARTICIPANTS

Forty patients with UCLA ± P who had alveolar bone grafting (ABG) between 2015 and 2020 and available preexpansion and postexpansion cone beam computed tomography (CBCT) scans. Twenty patients with UCLA ± P who underwent ABG without expansion were included as controls.

MAIN OUTCOME MEASURE

Percent change in width at the nasal pyriform, inferior turbinates, and alar base on cleft and noncleft sides.

RESULTS

The study included 40 patients (24 males, mean age 9.6 years) and 20 controls (10 males, mean age 10.1 years). After maxillary expansion, there was an increase in width on the cleft and noncleft sides compared to nonexpanded controls at nasal pyriform (10.9% cleft side, P ≤ 0.001 and 4.3% noncleft side, P ≤ .001), inferior turbinate (8.7%, P ≤ .001 and 4.5%, P = .01), and alar base (6.7%, P = <.001 and 0.8% P = .54). The increase in width was greater on the cleft side than the noncleft side at the nasal pyriform (7.1%, P ≤ .001), inferior turbinate (4.3%, P ≤ .001), and alar base (7.0%, P ≤ 0.001) in the expansion group. There was good to excellent intra-rater and inter-rater agreement for measurements.

CONCLUSION

Patients with UCLA ± P who undergo differential maxillary expansion before ABG exhibit greater nasal widening on the cleft side.

Does rapid maxillary expansion improve nasal airway obstruction? A computer fluid dynamics study in patients with nasal mucosa hypertrophy and obstructive adenoids

INTRODUCTION

Rapid maxillary expansion (RME) expands the maxillary dentition laterally and improves nasal airway obstruction. However, the incidence of nasal airway obstruction improvement after RME is approximately 60%. This study aimed to clarify the beneficial effects of RME on nasal airway obstruction in specific pathologic nasal airway diseases (nasal mucosa hypertrophy and obstructive adenoids) using computer fluid dynamics.

METHODS

Sixty subjects (21 boys; mean age 9.1 years) were divided into 3 groups according to their nasal airway condition (control, nasal mucosa hypertrophy, and obstructive adenoids), and those requiring RME had cone-beam computed tomography images taken before and after RME. These data were used to evaluate the nasal airway ventilation condition (pressure) using computer fluid dynamics and measure the cross-sectional area of the nasal airway.

RESULTS

The cross-sectional area of the nasal airway significantly increased after RME in all 3 groups. The pressures in the control and nasal mucosa groups significantly reduced after RME but did not change significantly in the adenoid group. The incidence of improvement in nasal airway obstruction in the control, nasal mucosa, and adenoid groups was 90.0%, 31.6%, and 23.1%, respectively.

CONCLUSIONS

The incidence of improvement in nasal airway obstruction after RME depends on the nasal airway condition (nasal mucosa hypertrophy and obstructive adenoids). In patients with nonpathologic nasal airway conditions, the obstruction may be sufficiently improved with RME. Furthermore, to some extent, RME may be effective in treating nasal mucosa hypertrophy. However, because of obstructive adenoids, RME was ineffective in patients with nasal airway obstruction.

The role of rapid maxillary expansion in pediatric obstructive sleep apnea: Efficacy, mechanism and multidisciplinary collaboration

This review aims to provide current knowledge about the efficacy, mechanism, and multidisciplinary collaboration of rapid maxillary expansion (RME) treatment in pediatric obstructive sleep apnea (OSA). OSA is a chronic disease characterized by progressively increasing upper airway resistance, with various symptoms and signs. Increasingly the evidence indicates that RME is a non-invasive and effective therapy option for children with OSA. Besides, the therapeutic mechanism of RME includes increasing upper airway volume, reducing nasal resistance, and changing tongue posture. Recent clinical researches and case reports also show that a multidisciplinary approach improves sleep-disordered breathing in children. Applied with adenotonsillectomy, mandibular advancement, continuous positive airway pressure, and comprehensive orthodontic treatment, RME can be more effective in recurrent or residual OSA.

Evaluation of computational fluid dynamics models for predicting pediatric upper airway airflow characteristics

Computational fluid dynamics (CFD) has the potential for use as a clinical tool to predict the aerodynamics and respiratory function in the upper airway (UA) of children; however, careful selection of validated computational models is necessary. This study constructed a 3D model of the pediatric UA based on cone beam computed tomography (CBCT) imaging. The pediatric UA was 3D printed for pressure and velocity experiments, which were used as reference standards to validate the CFD simulation models. Static wall pressure and velocity distribution inside of the UA under inhale airflow rates from 0 to 266.67 mL/s were studied by CFD simulations based on the large eddy simulation (LES) model and four Reynolds-averaged Navier-Stokes (RANS) models. Our results showed that the LES performed best for pressure prediction; however, it was much more time-consuming than the four RANS models. Among the RANS models, the Low Reynolds number (LRN) SST k-ω model had the best overall performance at a series of airflow rates. Central flow velocity determined by particle image velocimetry was 3.617 m/s, while velocities predicted by the LES, LRN SST k-ω, and k-ω models were 3.681, 3.532, and 3.439 m/s, respectively. All models predicted jet flow in the oropharynx. These results suggest that the above CFD models have acceptable accuracy for predicting pediatric UA aerodynamics and that the LRN SST k-ω model has the most potential for clinical application in pediatric respiratory studies.

Effects of rapid maxillary expansion on hearing loss and otitis media in cleft palate children

PURPOSE

Otitis media with effusion (OME), recurrent acute otitis media and conductive hearing loss (CHL) are significantly prevalent in children with cleft palate (CP) and cleft lip and palate (CLP). Rapid Maxillary Expansion (RME) appears to have a positive effect also on middle ear disorders in these patients. The study aims to offer a prospective evaluation of RME effects in a group of patients with CP/CLP in terms of OME, CHL.

METHODS

A prospective observational study was conducted. Thirty-four CP, CLP and submucosa cleft patients who received orthodontic indication to RME treatment for OME or conductive hearing loss in a tertiary institutional Care Unit of San Paolo Hospital, Milan (IT), were included. Twenty-two patients matched for age and with analogous inclusion criteria except for indication to RME treatment were enrolled in the control group. Clinical otolaryngological evaluation, pure tone audiometry and tympanogram were performed at the beginning of treatment (T0), at the end of the expansion (T1) and at 6-month follow-up (T2).

MAIN OUTCOME MEASURES

Air-bone gaps and tympanogram results at each time interval.

RESULTS

In the main group, RME allowed a statistically significant improvement of air-bone gaps (according to frequency, p < 0.001-0.089 T0 vs. T1 and < 0.001-0.044 T0 vs. T2, Friedman's test) and tympanometry results (p = 0.002 T0 vs. T1 and p < 0.001 T0 vs. T2, Friedman's test). Improvements were stable during follow-up and were significantly better in the main group than in the control group.

CONCLUSION

CHL and middle ear effusion improved significantly overtime during RME and after 6 months of follow-up.

Thermographic analysis of postoperative changes in the nasal breathing efficiency in infants and young children with unilateral cleft lip

PURPOSE

Nowadays, cheilorhinoseptoplasty is one of the most efficient methods of cleft lip primary surgical treatment eliminating both functional and esthetic issues. In this work, we have proposed, developed, and experimentally tested a new thermography-based algorithm for studying the efficiency and symmetry of nasal breathing prior to and after the surgery.

METHODS

To investigate and analyze the external respiration function of an infant with unilateral cleft lip after surgical respiration symmetry restoration followed by anatomically shaped postoperative endonasal retainer installation, we have applied contactless thermal imaging in real time.

RESULTS

The developed algorithm enables effective analysis of the respiratory function in infants before and after the surgery. Its combination with applied surgical technique experimentally demonstrated the potential of this approach for improving further the efficiency and symmetry of the airflows through the patient's nasal passages after the primary cheilorhinoseptoplasty.

CONCLUSIONS

The results of our study constitute a novel and promising avenue of investigation into the breathing function in infants and young children prior to and after their surgery for unilateral cleft lip. The adaptation of our technique to the conditions of a pediatric hospital will make it a safe and informative tool for noninvasive diagnosing the respiratory function in infants in the early postoperative period.

Evaluating the effect of midpalatal corticotomy-assisted rapid maxillary expansion on the upper airway in young adults using computational fluid dynamics

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.

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.