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

Expert consensus on pediatric orthodontic therapies of malocclusions in children

Malocclusion, identified by the World Health Organization (WHO) as one of three major oral diseases, profoundly impacts the dental-maxillofacial functions, facial esthetics, and long-term development of ~260 million children in China. Beyond its physical manifestations, malocclusion also significantly influences the psycho-social well-being of these children. Timely intervention in malocclusion can foster an environment conducive to dental-maxillofacial development and substantially decrease the incidence of malocclusion or reduce the severity and complexity of malocclusion in the permanent dentition, by mitigating the negative impact of abnormal environmental influences on the growth. Early orthodontic treatment encompasses accurate identification and treatment of dental and maxillofacial morphological and functional abnormalities during various stages of dental-maxillofacial development, ranging from fetal stages to the early permanent dentition phase. From an economic and societal standpoint, the urgency for effective early orthodontic treatments for malocclusions in childhood cannot be overstated, underlining its profound practical and social importance. This consensus paper discusses the characteristics and the detrimental effects of malocclusion in children, emphasizing critical need for early treatment. It elaborates on corresponding core principles and fundamental approaches in early orthodontics, proposing comprehensive guidance for preventive and interceptive orthodontic treatment, serving as a reference for clinicians engaged in early orthodontic treatment.

Breathing changes following mini-implant-supported maxillary skeletal expander treatment in late adolescent or adult patients : Assessment of objective and subjective functional breathing changes

PURPOSE

The aim of this study was to assess objective and subjective breathing changes in adult patients who underwent maxillary skeletal expansion with the mini-implant-supported maxillary skeletal expander (MSE).

METHODS

Twenty-nine patients (mean age 18.1 ± 4.3 years) who underwent expansion using the MSE were compared pre- and posttreatment and with a control group (mean age 19.9 ± 2.6 years) to assess objective and subjective functional breathing changes. Objective measurements of the airway including peak nasal inspiratory flow (PNIF) and peak oral inspiratory flow (POIF) were measured utilizing the In-Check medical device (Clement Clarke, Harlow, United Kingdom). Patients reported subjective breathing assessment utilizing the visual analog scale (VAS). Intragroup comparisons were performed with Wilcoxon tests and intergroup comparison with Mann-Whitney U tests. Spearman correlation coefficients were calculated among the studied variables (P < 0.05).

RESULTS

Following MSE treatment, there were significantly higher values for PNIF total (P < 0.0001), PNIF right (P < 0.0001), PNIF left (P < 0.0001), and POIF (P < 0.01) compared to pretreatment and control group results. Also, patients reported a significant decrease in troubled breathing as measured by the VAS for breathing through the right nostril (P < 0.01), left nostril (P < 0.001), and both nostrils (P < 0.01). Comparing the objective and subjective variables for both the pre-MSE or post-MSE groups, the results indicated no significant correlation between total PNIF and total VAS. However, the values had significant correlations between PNIF and VAS on each side when the patients were asked to block one nostril.

CONCLUSIONS

Objective functional breathing measurements were increased immediately after treatment with MSE. Subjective functional breathing measurements changes were significantly higher after MSE treatment and compared with the control group. MSE presents a nonsurgical alternative to achieving orthopedic expansion in adult patients which may provide a benefit for patients with nasal airway obstruction.

Respiratory Fluid Mechanics of the Effect of Mouth Breathing on High-Arched Palate: Computational Fluid Dynamics Analyses

Computational fluid dynamics (CFD) was introduced into the study of palate growth and development to explain the mechanisms by which mouth breathing affects palate descent from an aerodynamic perspective. Cone beam computed tomography (CBCT) data were used to reconstruct a 3-dimensional model during natural mouth breathing of a volunteer. The model was imported into CFX 19.0 for numerical simulation of nasal breathing, mouth-nasal breathing, and mouth breathing. The pressure in the oronasal cavity was analyzed, and the pressure difference between the oral and nasal surfaces of hard palate under different breathing patterns was calculated. CFD can be used to simulate the stress on the oral and nasal surfaces of the palate under different breathing patterns. The pressure differences and resultant force between the oral and nasal surfaces of the hard palate during nasal inspiration, nasal expiration, mouth-nasal inspiration, mouth-nasal expiration, mouth inspiration, and mouth expiration were 0 Pa, 4 Pa (upward), 9 Pa (upward), 3 Pa (downward), 474 Pa (upward), 263 Pa (downward), respectively, and 87.99 N (upward), 88.03 N (upward), 88.01 N (upward), 88.01 N (upward), 88.05 N (upward), 87.94 N (upward), respectively. Therefore, CFD can be used to investigate the growth and development of the palate. When the volunteer opened his mouth, the pressure difference between the oral and nasal surfaces of the hard palate was about 88 N upward regardless of whether there was airflow in the mouth. The reversal of the direction of the force on the hard palate may be one of the factors affecting its descent of it.

Condylar morphology and position changes after miniscrew-assisted rapid palatal expansion in skeletal Class III malocclusion adult patients with mandibular deviation and unilateral posterior crossbite

BACKGROUND

To evaluate the morphological and positional changes of mandibular condyle after miniscrew-assisted rapid palatal expansion (MARPE) in skeletal Class III malocclusion adult patients with horizontal mandibular deviation (MD).

METHODS

The sample consisted of 15 patients with MD (6 males and 9 females, mean age 21.58 ± 3.12 years). The CBCT scans were taken before and after MARPE immediately. The pre- and post-registered images of the cranial base and mandible were measured, respectively, by Mimics.

RESULTS

After expansion, the distance between superior condylar point and the Frankfort horizontal plane on the deviated side and the non-deviated side increased by 0.96 ± 0.60 mm (P = 0.011) and 0.70 ± 0.65 mm (P = 0.046); coronal condylar angle of the deviated side increased by 0.39° ± 0.34 (P = 0.028) and 0.06° ± 0.49 (P = 0.917) on the non-deviated side. No statistically significant differences were found when comparing the condylar position on both sides before and after treatment. The degree of mandibular deviation decreased 0.43 mm (P = 0.270).

CONCLUSIONS

This study suggested that for skeletal Class III malocclusion adult patients with horizontal MD, the condyle on the deviated side rotated toward the non-deviated side in the coronal direction; the condylar remodeling occurred mainly on the deviated side after MARPE in the vertical direction.

Upper airway changes in Class III patients using miniscrew-anchored maxillary protraction with hybrid and hyrax expanders: a randomized controlled trial

OBJECTIVES

The aim of this study was to compare the upper airway space changes after miniscrew-anchored maxillary protraction with hybrid (HH) and conventional hyrax (CH) expanders.

MATERIAL AND METHODS

The sample comprised Class III malocclusion growing patients that were randomized into two groups of miniscrew-anchored maxillary protraction. The group HH was treated with a hybrid hyrax appliance in the maxilla and two miniscrews distally to the canines in the mandible. Class III elastics were used from the maxillary first molar to the mandibular miniscrews until anterior crossbite correction. The group CH was treated with a similar protocol except for the conventional hyrax expander in the maxilla. Cone-beam computed tomography was obtained before (T1) and after 12 months of therapy (T2). The shape and size of upper airway were assessed. Intergroup comparisons were performed using Mann-Whitney U test (p < 0.05).

RESULTS

The group HH was composed of 20 patients (8 female, 12 male) with a mean age of 10.76 years. The group CH was composed of 15 patients (6 female, 9 male) with a mean age of 11.52 years. Anteroposterior and transverse increases of the upper airway were found for both groups. The oropharynx and the most constricted area increased similarly in both groups.

CONCLUSIONS

No differences in upper airway changes were observed using protraction anchored on hybrid or conventional hyrax expanders.

CLINICAL RELEVANCE

Maxillary protraction anchored on hybrid or conventional hyrax expanders may benefit patients with breathing disorders due to the increase of the upper airway volume and most constricted area. Registration: ClinicalTrials.gov (NCT03712007).

The Impact of Maxillary Expansion on Adults' Nasal Breathing: A Systematic Review and Meta-Analysis

OBJECTIVE

Nasal surgery fails to restore nasal breathing in some cases. Maxillary constriction is suggested as a major cause of failure. It is thought that maxillary constriction leads to the closure of the internal and external nasal valves. Moreover, it is well established in the literature that maxillary expansion, both in adults and children, increases upper airway volume. However, it is yet unclear whether maxillary expansion may improve nasal function.Review Methods: Pubmed (Medline), the Cochrane Library, EMBASE and Trip Database were checked by two authors from the Rhinology Study Group of the Young Otolaryngologists section of the International Federation of Otorhinolaryngological Societies. Two authors extracted the data. The main outcome was expressed as the value (in variable units) prior to treatment (T0), after expansion procedures (T1), after the retention period (T2), and after a follow-up period (T3).

RESULTS

A total of 10 studies (257 patients) met the inclusion criteria. The data pooled in the meta-analysis reveals a statistically significant reduction of 0.27 Pa/cm³/s (CI 95% 0.15, 0.39) in nasal resistance after palatal expansion As far as subjective changes are concerned, the pooled data for the change in the NOSE score shows a statistically significant mean reduction after maxillary expansion of 40.08 points (CI 95% 36.28, 43.89).

CONCLUSION

The initial available evidence is too limited to suggest maxillary expansion as a primary treatment option to target nasal breathing. However the data is encouraging with regards to the effect of maxillary expansion on nasal function. Further higher quality studies are needed in order to define clearer patient selection criteria, distinguish optimal techniques, and demonstrate long-term efficacy in long term follow up studies.

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.