|Year : 2015 | Volume
| Issue : 3 | Page : 139-144
Analysis of pharyngeal airway space and tongue position in individuals with different body types and facial patterns: A cephalometric study
Rohit Kulshrestha1, Ragni Tandon2, Kamlesh Singh3, Pratik Chandra4
1 PG Student, Department of Orthodontics and Dentofacial Orthopedics, Saraswati Dental College, Lucknow, Uttar Pradesh, India
2 Professor and Head of Department, Department of Orthodontics and Dentofacial Orthopedics, Saraswati Dental College, Lucknow, Uttar Pradesh, India
3 Professor, Department of Orthodontics and Dentofacial Orthopedics, Saraswati Dental College, Lucknow, Uttar Pradesh, India
4 Senior Lecturer Department of Orthodontics and Dentofacial Orthopedics, Saraswati Dental College, Lucknow, Uttar Pradesh, India
|Date of Submission||13-May-2015|
|Date of Acceptance||09-Aug-2015|
|Date of Web Publication||16-Sep-2015|
Room No. 3, PG Boys Hostel, Saraswati Dental College, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Aim: To evaluate if the different body types and facial patterns have any effect on the dimensions of the pharyngeal airway space and tongue position. Materials and Methods: Ninety subjects (age 13-30 years) with no history of previous orthodontic treatment, jaw surgeries, or functional jaw orthopedics were taken and divided into different groups based on their body built. They were further subdivided into different groups based on their Frankfort Mandibular Angle. Group I included 30 subjects (15 males, 15 females) who were ectomorphic (body mass index [BMI] < 20). Group II included 30 subjects (16 males, 14 females) who were mesomorphic (BMI between 20 and 25), and Group III included 30 subjects (14 males, 16 females) who were endomorphic (BMI > 25). Lateral cephalograms were traced manually to evaluate the pharyngeal airway passage and tongue position. Results: When the comparison between different facial growth patterns was done, differences in soft palate inclination (P < 0.004) and upper pharyngeal wall - pterygomaxillary (P < 0.012) was found to be statistically significant. A significant difference among different growth patterns was observed for the soft palate inclination between the hypo- and hyper-divergent groups (P < 0.003). No significant differences were seen when a comparison between different facial types (irrespective of growth) was done. No significant difference was seen in the position of the tongue in all the groups. Conclusion: Different body types and facial patterns had a significant effect on the dimension of the pharyngeal airway space but no significant effect on the position of the tongue.
Keywords: Facial pattern, pharyngeal airway passage, tongue position
|How to cite this article:|
Kulshrestha R, Tandon R, Singh K, Chandra P. Analysis of pharyngeal airway space and tongue position in individuals with different body types and facial patterns: A cephalometric study. J Indian Orthod Soc 2015;49:139-44
|How to cite this URL:|
Kulshrestha R, Tandon R, Singh K, Chandra P. Analysis of pharyngeal airway space and tongue position in individuals with different body types and facial patterns: A cephalometric study. J Indian Orthod Soc [serial online] 2015 [cited 2019 May 19];49:139-44. Available from: http://www.jios.in/text.asp?2015/49/3/139/165555
| Introduction|| |
Human beings are normally nasal breathers. The nasal and the oral cavities serve as pathways for respiratory airflow, however in some individuals due to nasal airway inadequacy or habit; the oral cavity becomes the predominant route for the respiratory airflow.  Changes in the dimensions of the respiratory tract that is, constriction can cause a decrease in airflow at times. 
There are significant relationships between the pharyngeal dimensions and craniofacial abnormalities.  Literature supports the notion that mandibular deficiency is frequently associated with a narrower pharyngeal airway passage.  Using computed tomography (CT), Trenouth and Timms  found that the effects of rapid maxillary expansion (RME) on the nasal cavity are not uniform and the changes in the nasal dimensions are progressively less toward the back of the nasal cavity. Mean cross-sectional nasal cavity enlargements of between 1.4 and 4 mm for rapid expansion, 0.8 mm for a quad helix, and 0.5 mm for a removable appliance have been reported. ,
According to Saitoh,  the growth of the face (excluding the mandible) is completed at a relatively early age. Sixty percent of craniofacial development takes place during the first 4 years of life and 90% by age 12. Based on these observations, any intervention to open the airway must take place at an early age. A significant relationship exists between airway space and facial morphology; also, airway space may be affected by conditions such as functional anterior shifting, head posture, sagittal skeletal relation, and maxillary protraction.  There are not enough studies which describe the dimensions of the pharyngeal air space and tongue position among subjects with different body types and facial patterns. To overcome the lacuna which was seen in the previous studies the present study was done to assess the pharyngeal airway space dimension and position of the tongue in individuals of different body builts and with different facial patterns.
| Materials and Methods|| |
Pretreatment lateral cephalograms of patients were taken from the Department of Orthodontics and Dentofacial Orthopaedics, Saraswati Dental College, Lucknow, who came for orthodontic treatment.
Each subject met the following inclusion criteria:
- Aged between 13 and 30 years
- No history of previous orthodontic treatment or functional jaw orthopedic treatment
- No history of trauma or any surgery involving the jaws and adenoids (Quincy)
- No breathing disorders (such as snoring, or obstructive sleep apnea)
- No history of cleft lip and palate, nasal stenosis, and any systemic disease affecting normal growth.
Based on the body mass index (BMI) = Mass (kg)/height (meters) 2 , all the subjects were divided into three groups. In addition, each group was further divided into subgroups according to their Frankfort Mandibular Angle (FMA) (hypodivergent, normal, and hyperdivergent) [Table 1]. Ninety subjects were taken in the study after the inclusion criteria were used (30 subjects in each group). Each subgroup had 10 subjects.
- Group I included 30 ectomorphic subjects with their BMI <20
- Group II included 30 mesomorphic subjects with their BMI between 20 and 25
- Group III included 30 endomorphic subjects with their BMI >25.
All of the cephalograms were recorded with the same exposure parameters (kVp - 80, mA - 10 exposure time 0.5 s) with the same magnification and the same machine (Kodak 8000C Digital and Panoramic System Cephalometer Rochester, NY, USA) The cephalogram was exposed at the end-expiration phase of the respiration. All cephalograms were traced manually using lead acetate paper and 4B tracing pencil by the same operator. Various landmarks [Figure 1], reference planes, linear, and angular parameters [Figure 2] used for the evaluation of the pharyngeal airway space and tongue position were based on methods described by Jena et al. and Ucar and Uysal.  Once the subjects BMI and FMA were taken they were placed into their respective groups.
|Figure 2: Various cephalometric reference planes and linear and angular parameters|
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A master file was created, and the data was statistically analyzed on a computer with Statistical Package for Social Sciences (version 17) (SPSS Inc. Released 2008. Chicago: SPSS Inc). A data file was created under dBase and converted into a microstat file. The data was subjected to descriptive analysis for mean, standard deviation, range, and 95% confidence interval. Group differences were analyzed with one-way analysis of variance. For multiple comparisons, a post-hoc Tukey honestly significant difference test was used. To identify the errors associated with the radiographic measurements, 15 radiographs were selected randomly. Their tracings and measurements were repeated 8 weeks after the first measurements were taken. A paired sample t-test was applied to the first and second measurements, and the differences between measurements were insignificant.
| Results|| |
When comparison in different facial growth patterns was done, statistically significant differences in SNB (P < 0.007), ANB (P < 0.001), gonial angle (P < 0.001), y-axis (P < 0.001), soft palate inclination (P < 0.004), and upper pharyngeal wall - pterygomaxillary (P < 0.012) (hypodivergent, normal, and hyperdivergent groups) were found [Table 2]. When the comparison between growth patterns was done, statistically significant difference was seen in the gonial angle and y-axis (P < 0.001) between the hypodivergent and normal groups. Statistically significant difference was seen in SNB angle (P < 0.005), ANB angle (P < 0.001), gonial angle (P < 0.001), y-axis (P < 0.001), and soft palate inclination (P < 0.003) between the hypo- and hyper-divergent groups. Statistical significant differences were also seen in the gonial angle (P < 0.031), y-axis (P < 0.001) between the normal and hyperdivergent groups [Table 3]. No significant differences were seen when comparison in different body types (irrespective of growth) was done [Table 4]. None of the differences was significant statistically when the comparison was done between body types (respective of growth) [Table 5].
|Table 2: Comparison of all parameters in different facial growth patterns irrespective of facial type|
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|Table 4: Comparison of different body types irrespective of growth pattern|
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The upper pharyngeal airway space was greatest in the mesomorphic/normal Group V while it was lowest in the ectomorphic/normal Group II, the differences were not statistically significant. The lower pharyngeal airway space was greatest in the endomorphic/hyperdivergent Group VII while it was lowest in the ectomorphic/hypodivergent Group III, the differences were not statistically significant. The tongue was most forwardly placed in the mesomorphic/normal Group V while it was most backwardly placed in the mesomorphic/hypodivergent Group IV; the difference was not statistically significant. The depth of the nasal cavity was greatest in the ectomorphic/hypodivergent Group I while it was the least in the endomorphic/normal Group VIII, the difference was not statistically significant.
| Discussion|| |
The pharynx is a tube-shaped structure that plays an important role in respiration and deglutition. , The dimensions of the pharynx continue to grow rapidly until 13 years of age and then there is a minimal growth until adulthood.  The depth of the upper pharyngeal airway increases with age, whereas the depth of the lower pharyngeal airway is established in early life.  Taylor et al. reported no significant change in the depth of the nasopharynx after 12 years of age. Hyperdivergent patients with certain skeletal features such as the retrusive mandible and vertical maxillary excess, may have narrower antero-posterior airway dimensions. , The role of fat deposition in the pharyngeal wall and the resulting narrowing of the pharyngeal airway space are not clear in the literature, they might have an important role in airway obstruction. 
Various studies have stated that cephalometric films are significantly reliable and reproducible in determining airway dimensions. ,, Kerr  reported that Class II malocclusion subjects showed narrow nasopharyngeal airway space compared to Class I and normal occlusion subjects.
The size of the nasal cavity in the current study did not show any significant difference. Negative readings were seen mainly due to the fact the linear measurements were being taken on a two-dimensional (2D) cephalogram while the structure is three-dimensional (3D). This is supported by studies done by Grauer et al. and Jena et al.  This could be the case because the dimensions of the bony nasopharynx are a relative dependent variable in relation to other dimensions of the facial complex.  Grauer et al. used cone-beam CT records of 62 nongrowing patients to evaluate the pharyngeal airway volume (superior and inferior compartments) and shape.
Few studies have shown that there is an increase in the nasal airway volume after RME. ,, The opening of the mid palatal suture leads to the lateral displacement of the two halves of the maxilla. This leads to increase in size, which helps in nasal respiration as there is an increase in the airway space. 
The soft palate was elongated in the ectomorphic group in most of the groups. This can be due to the lack of fat deposition in the soft palate region.  The inclination and thickness were seen higher in the endomorphic group. The inclination showed a statistically significant difference among the three groups based on facial growth patterns. Tangugsorn et al. took lateral cephalograms of 100 subjects and divided them into two groups based on BMI while Jena et al. took lateral cephalograms of 91 subjects and divided them into three groups based on the sagittal mandibular development, both the studies showed the same result.
In the present study, the position of the tongue shows no significant difference between all the groups. The FMA and the BMI played no role in the position of the tongue. We previously reported changes in tongue posture with the respiratory mode and indicated that the tongue moved forward during oral respiration. ,, It has also been reported that the posterior part of the tongue body moved antero-inferiorly during oral respiration.  Takahashi et al. recorded the EMG activities of the masseter and anterior temporalis muscles in 10 skeletal Class I adults found that the position of the tongue varies greatly in patients with different malocclusions.
The antero-posterior dimension of the upper airway is usually maintained by the adaptation of both tongue and hyoid bone. , The hyoid bone is located more posterior in Class II skeletal pattern, the genioglossus, the main protruder of the tongue, generates upper airway dilating forces to maintain upper airway patency. 
The ANB angle showed statistically significant difference between the ectomorphic/hyperdivergent and the endomorphic/hypodivergent, endomorphic/hyperdivergent groups. This may be due to the fact that in hyperdivergent cases the mandible may be rotated downward and forward which may lead to forward or backward positioning of point B. Ceylan and Oktay  found that changes in the ANB angle may affect nasopharyngeal airway size and that the oropharyngeal space was reduced in subjects with an increased ANB angle.
The gonial angle showed a significant difference in many groups. This is mainly due to the growth pattern (horizontal, vertical) of the individual patient along with the downward and backward rotation of the mandible. This significance could be seen as the groups for the study were made according to the FMA. The FMA was taken according to the one defined by Downs.  The gonial angle has no significant role in the dimensions of the pharyngeal airway space and position of the tongue. The recent study by Hwang et al. showed that airway space measurements in low and neutral angle Class II subjects did not differ from those of the skeletal Class I control group, while in the high-angle groups upper airway space was significantly smaller. Ucar and Uysal  also found that vertical growth patterns, but not malocclusion type, influenced upper airway dimensions. They reported a significant difference between a low angle and high angle Class I groups at the level of the nasopharyngeal airway space and they showed that vertical growth patterns have significant correlations with the upper portion of pharyngeal airways.
The y-axis also showed a significant difference between groups. As stated earlier this was seen due to the nature of the grouping system. Akcam et al. in their study took 72 lateral cephalograms while Sheng et al.  took 239 lateral cephalograms, and they both showed that skeletal morphology plays an important role in the development of the craniofacial structures. Other studies also showed the same result. ,, The upper and lower pharyngeal space in the all the patients was nearly the same and showed no statistical significance. This was also seen in other studies where cone-beam CT was used instead of lateral cephalogram. ,,
Lateral cephalograms suffer from severe limitations with inherent errors such as 2D representation of a distorted 3D structure, differences in magnifications, superimposition of bilateral craniofacial structures, and low reproducibility as a result of difficulties in landmark identification.  Another important drawback of lateral cephalograms is the lack of information about cross-sectional area and volume. Further studies are required which will evaluate the airway flow capacity, the role of gender dimorphism, malocclusion, and different growth patterns in the pharyngeal airway space and tongue position.
| Conclusion|| |
- The upper pharyngeal airway space was greatest in the mesomorphic/normal Group V while it was lowest in the ectomorphic/normal Group II
- The lower pharyngeal airway space was greatest in the endomorphic/hypodivergent Group VII while it was lowest in the ectomorphic/hyperdivergent Group III
- The soft palate thickness, length, and inclination was greatest in the ectomorphic/hypodivergent Group I, mesomorphic/normal Group V and endomorphic/hyperdivergent Group IX, respectively. It was lowest in endomorphic/normal Group VIII, endomorphic/hyperdivergent Group IX and ectomorphic/hyperdivergent Group III
- The tongue was most forwardly placed in the mesomorphic/normal Group V while it was most backwardly placed in the mesomorphic/hypodivergent Group IV
- The depth of the nasal cavity was greatest in the ectomorphic/hypodivergent Group I while it was least in the endomorphic/normal Group VIII
- Growth pattern had an independent impact on parameters irrespective of facial type whereas facial type had a limited role independent of growth pattern.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]