JICDRO is a UGC approved journal (Journal no. 63927)

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ORIGINAL RESEARCH
Year : 2019  |  Volume : 11  |  Issue : 2  |  Page : 83-89

To compare volumetric dimensions of pharyngeal airway for different dentofacial skeletal patterns – Cone beam computed tomography


1 Department of Orthodontics and Dentofacial Orthopedics, Bharati Vidyapeeth Deemed to be University, Dental College and Hospital, Pune, Maharashtra, India
2 Department of Endodontics and Conservative Dentistry, Bharati Vidyapeeth Deemed to be University, Dental College and Hospital, Pune, Maharashtra, India

Date of Submission01-May-2019
Date of Decision09-May-2019
Date of Acceptance13-Jun-2019
Date of Web Publication23-Dec-2019

Correspondence Address:
Dr. Madhura A Jadhav
Department of Orthodontics and Dentofacial Orthopedics, Bharati Vidyapeeth Deemed to be University, Dental College and Hospital, Pune - 411 043, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jicdro.jicdro_8_19

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   Abstract 


After a century of controversies, we are still not certain on the relationship between airway dimensions and facial morphology. Objective: The objective of the study was to measure nasopharyngeal airway dimensions and compare it among different skeletal patterns. Materials and Methods: Forty-five cone-beam computed tomography (CBCT) scans of patients between 16 and 25 years were used in the study. The nasopharyngeal airway was divided into upper, middle, and lower segments. CBCT images were grouped into skeletal Class I, Class II, and Class III. Results: There is no statistically significant difference between all the three groups for mean height of the upper, middle, and lower pharyngeal airways (P = 0.303, 0.479, and 0.077, respectively). There is no statistically significant difference between all the three groups for mean width of the upper, middle, and lower pharyngeal airways indicated by P = 0.643, 0.791, and 0.99, respectively. There is no statistically significant difference between all the three groups for mean breadth of the upper, middle, and lower pharyngeal airways (P = 0.939, 0.48, and 0.068, respectively). Furthermore, the mean total height of pharyngeal airway in Class I, Class II, and Class III groups indicates no statistically significant difference (P = 0.097).
Conclusion: Nasopharyngeal airway dimensions seem to play no role in different skeletal patterns.

Keywords: Cone-beam computed tomography, dimensions, pharyngeal airway


How to cite this article:
Jadhav MA, Bhosale VI, Jadhav AB. To compare volumetric dimensions of pharyngeal airway for different dentofacial skeletal patterns – Cone beam computed tomography. J Int Clin Dent Res Organ 2019;11:83-9

How to cite this URL:
Jadhav MA, Bhosale VI, Jadhav AB. To compare volumetric dimensions of pharyngeal airway for different dentofacial skeletal patterns – Cone beam computed tomography. J Int Clin Dent Res Organ [serial online] 2019 [cited 2020 May 25];11:83-9. Available from: http://www.jicdro.org/text.asp?2019/11/2/83/273766




   Introduction Top


The nasopharyngeal airway includes adenoid, a complex network of lymphatic tissues located in the posterior area.[1] In growing children, predisposing factors, repeated infection, or inflammation usually leads to adenoid hypertrophy and constriction of the posterior airway. Children with narrowed nasopharynx tend to use mouth breathing because of partially impaired nasal respiration function. The ways in which variation in the airflow can influence growth and development are not completely elucidated. These questions remain unanswered because of (i) methodologic limitations related among other factors, (ii) the multifactorial etiology of malocclusion, (iii) the limitations in the cephalometric method, and (iv) the lack of longitudinal studies assessing the airway.[2] The oropharyngeal airway lies between the soft palate and the hyoid bone. Despite the vast amount of research concerning airway anatomy and its influence on craniofacial growth and development, most studies have used two-dimensional, lateral or frontal cephalograms with a limited equation of lengths and areas. As cone-beam computed tomography (CBCT) scan uses a different type of acquisition than traditional multislice CT, radiation is reduced.[3] Providing three-dimensional (3D) reconstructed images from multiple sequential planar projection images and allows the visualization of sites of interest by adjusting the image orientation and rotation. Recent quantitative 3D assessment of the pharyngeal airway revealed that the relationships between pharyngeal airway form and head posture or facial pattern among children with Class I, II, and III malocclusions are controversial.[1] Thus, our study includes the dimension assessment of pharyngeal airway in different dentofacial skeletal patterns.

Limitations of this study were as follows: 3D volumetric measurements of airway were not done, and though the pharyngeal airway is curved, linear measurements were taken from point A to Z.


   Materials and Methods Top


As the shape and size of the pharyngeal airway are irregular, curved, and conical, for accuracy and convenience, it was decided to divide the nasopharyngeal airway into three segments: upper, middle, and lower. Forty-five images were chosen which satisfied the inclusion criteria of full permanent dentition. The nasopharyngeal dimensions continue to grow rapidly until adulthood, so the age group selected for this study was between 16 and 25 years. Exclusion criteria included (i) very high-angle Frankfort-mandibular plane angle (FMA) (35–40°), (ii) very low-angle FMA (<10-15°), and (iii) noticeable pharyngeal pathology. All the images were divided into three groups as Group 1 (Class I group) having ANB angle of 1–4°, Group 2 (Class II group) having ANB angle ≥4°, and Group 3 (Class III group) having ANB angle <1°. Angle ANB was measured on the print of lateral view image (true size image). To standardize the measurements and minimize errors, all images were reoriented in a fixed position using the palatal plane as a reference plane. Each image was oriented in such a way that the palatal plane was always kept parallel to the central horizontal line of the grid of the software. Four planes were marked on each image [Figure 1] and [Table 1].
Figure 1: four planes used: anterior plane, hard palatal plane, soft palate plane, and epiglottis plane

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Table 1: Formation of four planes such as anterior plane, hard palate plane, soft palate plane, and epiglottis plane for demarcating the extent to measurement pharyngeal volume

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CBCT machine (i-Cat 17/19 C, Imaging Sciences International, USA) was used with exposure voltage of 120 kv, current of 5 mA, and exposure time of 27 s per patient. These images were loaded in Invivo 5.1 software, viewer version 1.9 of CBCT machine (I Cat 17/19C, Imaging Sciences International, USA), and stored in JPEG format.

All the above it when extended toward nasopharynx, planes divided the nasopharynx into three parts: upper, middle, and lower pharyngeal airways. All these planes also become the upper and lower boundaries of respective nasopharyngeal segments. Height, width, and breadth of the upper [Figure 2], middle [Figure 3], and lower [Figure 4] pharyngeal airways were measured. The total height of nasopharyngeal airway was also measured.
Figure 2: height measurements for the upper (a), middle (b), and lower (c) pharyngeal airways

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Figure 3: width measurements for the upper (a), middle (b), and lower (c) pharyngeal airways in frontal view

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Figure 4: Breadth measurements for the upper (a), middle (b), and lower (c) pharyngeal airways in sagittal view

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As the shape of the pharynx is more irregular, cylindrical, and curved, it was decided to measure the height, width, and breadth of the upper, middle, and lower airways at each two locations and then take the average of the two. Measuring tool was inbuilt in Invivo 5.1 software itself.

Height measurements

In the sagittal view, nine points [Figure 2] were marked: (a) posterior and superior most point on anterior surface of posterior pharyngeal wall at soft tissue covering of the base of the sphenoid; (b) intersection of anterior surface of posterior pharyngeal wall and hard palate plane; (c) intersection of soft tissue covering of base of sphenoid bone and anterior plane; (d) intersection of anterior plane and hard palate plane; (e) intersection of anterior surface of posterior pharyngeal wall and soft palate plane; (f) intersection of soft palate plane and posterior surface of soft palate; F'-point on posterior surface of soft palate at its greatest curvature; (g) intersection of anterior surface of posterior pharyngeal wall and soft palate plane; and (h) intersection of base of tongue and epiglottis plane.

Height was measured in millimeter at two locations for each segment of pharyngeal airway. Upper, middle, and lower pharyngeal airway height was measured and denoted as UH1, UH2, MH1, MH2, LH1, and LH2, respectively. All H1 measurements were done on the posterior part of the airway, and all H2 measurements were done on the anterior part of the airway.

UH1 was height measured between points A and B. UH2 was measured between points C and D. Similarly, MH1 was height measured between points B and E. MH2 height measurement was done in two steps. First, the distance between point D and F' was measured, and then, the distance between points F' and F was measured. This was done because the anterior part of the middle pharyngeal airway is more curved. For lower pharyngeal airway height measurement, LH1 distance was measured between points E and G, and LH2 measurement was done between points F and H. The average of all H1 and H2 measurements was taken, and the final height of the upper, middle, and lower pharyngeal airways was denoted as UH, MH, and LH, respectively.

Width measurements

In the frontal view of the CBCT, 12 points [Figure 3] were marked: (i) intersection of right lateral wall of upper pharyngeal airway and soft tissue covering of base of the sphenoid bone; (j) intersection of left lateral wall of upper pharyngeal airway and soft tissue covering of base of the sphenoid bone; (k) intersection of right lateral pharyngeal wall and midpoint of base of upper pharyngeal airway; (l) intersection of left lateral pharyngeal wall and midpoint of base of upper pharyngeal airway; (m) intersection of right lateral pharyngeal wall and hard palate plane; (n) intersection of left lateral pharyngeal wall and hard palate plane; (o) intersection of right lateral pharyngeal wall and midpoint of base of middle pharyngeal airway; (p) intersection of left lateral pharyngeal wall and midpoint of base of middle pharyngeal airway; (q) intersection of right lateral pharyngeal wall and soft palate plane; (r) intersection of left lateral pharyngeal wall and soft palate plane; (s) intersection of right lateral pharyngeal wall and midpoint of base of lower pharyngeal airway; and (t) intersection of left lateral pharyngeal wall and midpoint of base of the lower pharyngeal airway.

The width was measured in millimeter at two locations. They were denoted as UW1, UW2, MW1, MW2, LW1, and LW2 for upper, middle, and lower pharyngeal width, respectively [Figure 3]a, [Figures 3]b, [Figures 3]c. All W1 measurements were done at the upper part of each segment of the airway, and all W2 measurements were done at the center of the base of each airway when viewed from the base.

UW1 was width measured between points I and J. UW2 was measured between points K and L. Similarly, MW1 was width measured between points M and N. MW2 width was measured between points O and P. LW1 distance was measured between points Q and R, and LW2 measurement was done between points S and T. The average of all W1 and W2 measurements for each airway was taken, and the final width of the upper, middle, and lower pharyngeal airways was denoted as UW, MW, and LW, respectively.

Breadth measurements

In the sagittal view, additional six points [Figure 4] were marked: (u) intersection of anterior surface of posterior pharyngeal wall and midpoint of base of the upper pharyngeal airway; (v) intersection of posterior surface of hard palate and midpoint of base of upper pharyngeal airway; (w) intersection of anterior surface of posterior pharyngeal wall and midpoint of base of middle pharyngeal airway; (x) intersection of posterior surface of soft palate and midpoint of base of middle pharyngeal airway; (y) intersection of anterior surface of posterior pharyngeal wall and midpoint base of lower pharyngeal airway; and (z) intersection of base of tongue and midpoint of base of lower pharyngeal airway.

Breadth was measured in millimeter at two different locations. They were denoted as UB1, UB2, MB1, MB2, LB1, and LB2. All B1 measurements were done at the upper part of each segment of the airway, and all B2 measurements were done at the lower part but when viewed from the base.

UB1 was breadth measured between points A and C. UB2 was measured between points U and V. Similarly, MB1 was breadth measured between points B and D. MB2 was measured between points W and X. LB1 distance was measured between points E and F, and LB2 measurement was done between points Y and Z. The average of all B1 and B2 measurements for each airway was taken, and the final breadth of the upper, middle, and lower pharyngeal airways was denoted as UB, MB, and LB, respectively.

All statistical analyses were carried out using the Statistical Package for the Social Sciences software (SPSS Inc. version 17.0 I-cat 17/19C, imaging sciences International, California, USA). One-way analysis of variance test was used to compare the volumetric measurements.


   Results Top


[Table 2] depicts the mean and standard deviation of height, width, and breadth of the upper, middle, and lower pharyngeal airways in all the three groups.
Table 2: Mean height, breadth, and width (mm) of the upper, middle, and lower pharyngeal airways in all three groups

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When compared, there is no statistical significance in the mean height, mean width, and mean breadth in the upper, middle, and lower pharyngeal airways among all the three groups. This shows that the mean height, width, and breadth of the upper, middle, and lower pharyngeal airways in all the three groups were the same.

[Table 3] depicts the mean and standard deviation of the total height of pharyngeal airway in all the three groups. P = 0.097 signifies that there is no statistically significant difference in the mean total height of pharyngeal airway in different skeletal types, indicating that the total height of the pharyngeal airway is similar among the three groups [Figure 5].
Table 3: Mean total height (mm) of pharyngeal airway in all three groups

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Figure 5: comparison of height, breadth, and width of the upper pharyngeal airways in Group 1, Group 2, and Group 3

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   Discussion Top


When compared statistically among all the three groups, upper pharyngeal airway height, width, and breadth measurements do not show a statistically significant difference as is indicated by P = 0.303, 0.939, and 0.643, respectively. This signifies that the height, width, and breadth of the upper pharyngeal airway are almost the same among all the three groups.

Findings of the present study are in agreement with de Freitas et al.[2] whose results also showed that the type of malocclusion does not change the upper pharyngeal airway width. Takemoto et al.[3] reported in their study that there was no difference in the upper pharyngeal width between Class I and Class III groups.

However, Zhong et al.[4] reported a decrease in the upper airway dimensions in the inferior part (palatopharynx and hypopharynx) in Class III malocclusion cases than in Class II malocclusion cases. Similarly, the upper airway dimensions were also reduced in Class II cases when compared with Class I malocclusion cases. This reveals a close relationship between the upper airway passage and positioning of the jaws.

Going through the literature, no reference was found regarding the dimensions of the middle pharyngeal airway.

When compared statistically among all the three groups, middle pharyngeal airway height, width, and breadth measurements do not show a statistically significant difference as is indicated by P = 0.479, 0.48, and 0.791, respectively. This signifies that the height, width, and breadth of the middle pharyngeal airway are almost the same among all the three groups [Figure 6].
Figure 6: comparison of height, breadth, and width of the middle pharyngeal airway in Group 1, Group 2, and Group 3

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When compared statistically among all the three groups, lower pharyngeal airway height, width, and breadth measurements do not show a statistically significant difference as is indicated by P = 0.077, 0.068, and 0.99, respectively. This signifies that the height, width, and breadth of the lower pharyngeal airway are almost the same among all the three groups [Figure 7].
Figure 7: comparison of height, breadth, and width of the lower pharyngeal airway in Group 1, Group 2, and Group 3

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The findings of this study are in agreement with the findings of de Freitas et al.[2] whose results showed that skeletal malocclusion types do not influence the lower pharyngeal airway width.

However, Takemoto et al.[3] reported in their study that the lower pharyngeal width of prognathic girls (Class III group) was significantly larger than that of girls with normal occlusion. They also concluded that Class II patients have a tendency for narrower anteroposterior pharyngeal dimensions, specifically in the nasopharynx at the level of the hard palate and in the oropharynx at the level of the tip of the soft palate and the mandible.

[Table 3] reveals the mean total pharyngeal airway height for all the three groups. When compared statistically, P = 0.097 signifies that there is no statistically significant difference in the mean total height of pharyngeal airway in different skeletal types, indicating that the total height of the pharyngeal airway is almost same in all the three skeletal groups [Figure 8].
Figure 8: comparison of total pharyngeal height in Group 1, Group 2, and Group 3

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Findings of the study conducted by Iwasaki et al.[5] showed that a Class III malocclusion is associated with a large oropharyngeal airway compared with the Class I malocclusion. Abu Allhaija ES and Al-Khateeb[6] stated that vertical airway length was reduced in Class II participants with P < 0.01.

The mean height, width, and breadth of the upper, middle, and lower pharyngeal airways in our study do not show statistically significant difference among all the three groups. The mean total pharyngeal height is also not significant statistically among all the three study groups.


   Conclusion Top


When nasopharyngeal airway dimensions, height, width, breadth, and total pharyngeal height, were compared among different skeletal patterns, the following results of the study can be concluded as:

  1. There is no statistically significant difference between all the three groups for mean height of the upper, middle, and lower pharyngeal airways indicated by P = 0.303, 0.479, and 0.077, respectively [Table 2]
  2. There is no statistically significant difference between all the three groups for mean width of the upper, middle, and lower pharyngeal airways indicated by P = 0.643, 0.791, and 0.99, respectively [Table 2]
  3. There is no statistically significant difference between all the three groups for mean breadth of the upper, middle, and lower pharyngeal airways indicated by P = 0.939, 0.48, and 0.068, respectively [Table 2]
  4. The mean total height of pharyngeal airway in Class I, Class II, and Class III groups indicates no statistically significant difference (P = 0.097), which signifies that total pharyngeal height in all the three groups is similar [Table 3].


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Oh KM, Hong JS, Kim YJ, Cevidanes LS, Park YH. Three-dimensional analysis of pharyngeal airway form in children with anteroposterior facial patterns. Angle Orthod 2011;81:1075-82.  Back to cited text no. 1
    
2.
de Freitas MR, Alcazar NM, Janson G, de Freitas KM, Henriques JF. Upper and lower pharyngeal airways in subjects with class I and class II malocclusions and different growth patterns. Am J Orthod Dentofacial Orthop 2006;130:742-5.  Back to cited text no. 2
    
3.
Takemoto Y, Saitoh I, Iwasaki T, Inada E, Yamada C, Iwase Y, et al. Pharyngeal airway in children with prognathism and normal occlusion. Angle Orthod 2011;81:75-80.  Back to cited text no. 3
    
4.
Zhong Z, Tang Z, Gao X, Zeng XL. A comparison study of upper airway among different skeletal craniofacial patterns in nonsnoring Chinese children. Angle Orthod 2010;80:267-74.  Back to cited text no. 4
    
5.
Iwasaki T, Hayasaki H, Takemoto Y, Kanomi R, Yamasaki Y. Oropharyngeal airway in children with class III malocclusion evaluated by cone-beam computed tomography. Am J Orthod Dentofacial Orthop 2009;136:318.e1-9.  Back to cited text no. 5
    
6.
Abu Allhaija ES, Al-Khateeb SN. Uvulo-glosso-pharyngeal dimensions in different anteroposterior skeletal patterns. Angle Orthod 2005;75:1012-8.  Back to cited text no. 6
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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