Objectives
1. To define the normative airway of Chinese population using three-dimensional imaging and computer analysis
2. To evaluate the upper airway differences in patients with normal facial profile and those with skeletal class III deformity
3. To evaluate the differences in upper airway models among patients with different dentofacial deformities and describe the role of computational fluid dynamics (CFD) in the human upper airway
Materials and Methods
Part I : Three-Dimensional Analysis of the Normative Upper Airway in Chinese
This was a cross-sectional observational study. Cone beam computerized tomography (CBCT) scans of one hundred patients were analyzed. Computer analysis of the different upper airway parameters were studied including airway length and volume, as well as airway dimensions at the axial level of the soft palate, hard palate, base of tongue, and epiglottis. The most constricted airway location was identified and correlation analysis with variables of interest was done.
Part II: A Cone Beam Computerized Tomography Study of Airway in Skeletal Class I and Class III
Cone-beam computed tomography (CBCT) records of 200 patients were used to evaluate the upper airway dimensions. This sample consisted of patients with normal facial profile (Class I) and those demonstrating skeletal class III deformities. Computer analysis of the upper airway parameters such as airway length, airway volume, airway anterior-posterior and cross-sectional area dimensions at the hard palate, soft palate, base of tongue and epiglottis were performed. The most constricted airway sites were identified.
Part III: Computational fluid dynamics study of upper airway in different dentofacial deformities
Cone-beam computed tomography records of 12 patients were used to evaluate the upper airway. This sample consisted of facial skeletal Class I, II and III subjects. The upper airway models were constructed to allow CFD simulations in the airway from the epiglottis to the hard palate. Cross-sectional area, pressure, velocity and resistance were measured based on the reconstructed meshed models.
Results
Part I : Three-Dimensional Analysis of the Normative Upper Airway in Chinese
In 100 subjects (40 males, 60 females) aged 16-40 years with normal facial profile, we found that the most constricted site occurs at the level of the soft palate. This surface area of this site was found to be linearly correlated to the airway volume, suggesting a significant relationship between the most constricted area and the total airway volume. Gender differences were found in airway length, volume, and in the dimensions at the base of tongue and epiglottis region. The mean airway length was 54.12 mm + 6.19 for males and 49.25 mm + 4.86 for females; airway volume of 15.09 cm3 + 4.92 for males and 13.12 cm3 + 4.72 for females.
Part II: A Cone Beam Computerized Tomography Study of Airway in Skeletal Class I and Class III
The sample consisted of 100 Class I (41 males, 59 females) with a mean age of 25.4 years and 100 Class III (38 males, 62 females) with a mean age of 23.5 years. Gender differences were noted in the airway length, airway volume and dimensions at the base of tongue and epiglottis for both groups. Males showed longer airway length, larger airway volume, larger airway dimensions at the base of tongue and epiglottis compared to females. Significant differences in all the airway parameters between the two groups were found except for airway length. The soft palate was found to be the most constricted airway site observed in the Class I subjects while Class III subjects showed restriction in both the soft palate and epiglottis region.
Part III: Computational fluid dynamics study of upper airway in different dentofacial deformities
The airflow was variable among airway in different skeletal deformities. The pressure changes along airway of Class II were the largest, followed by Class I. The pressure drop in the airway of Class III subjects were the smallest. The larger pressure differences would cause greater resistance in the airway. The highest resistance was observed in the airway of Class II subjects.
Conclusion
Part I : Three-Dimensional Analysis of the Normative Upper Airway in Chinese
This airway data provide a normative reference that can be used in various dentofacial analysis as well as for diagnosis and treatment planning for related dentofacial deformities and in understanding the pathophysiology for sleep-related breathing disorders.
Part II: A Cone Beam Computerized Tomography Study of Airway in Skeletal Class I and Class III
The upper airway is larger in patients with Class III deformity than those with a normal facial profile. The site of restriction is commonly observed at the soft palate in the Class I group whereas patients with Class III deformity, the airway restriction sites are at both the soft palate and epiglottis. Understanding of the upper airway differences in between class I and class III facial deformities can have implications on treatment planning for orthognathic surgery.
Part III: Computational fluid dynamics study of upper airway in different dentofacial deformities
The results in this study suggest that skeletal pattern showed a significant correlation with pressure and resistance along the upper airway. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/180083 |
| Date | January 2012 |
| Creators | Chong, Mei-man., 臧薇敏. |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B48542027 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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