Three-Dimensional Computed Tomography Analysis of Airway Volume Changes Between Open
and Closed Jaw Positions
Authors: Leslie Glupker1, Katherine Kula1, Edwin Parks2, William Babler2, Kelton Stewart1 and Ahmed
Ghoniema1
1: Department of Orthodontics and Oral Facial Genetics, Indiana University School Dentistry,
Indianapolis, IN, USA
2: Department of Oral Pathology, Medicine & Radiology, Indiana University School of Dentistry,
Indianapolis, IN, USA

Corresponding author:
Ahmed Ghoneima
Indiana University School of Dentistry
Department of Orthodontics and Oral Facial Genetics
1121 West Michigan Street, DS 201
Indianapolis, IN 46202
Phone: 317-278-1653
Fax: 317-278-1438
Email: aghoneim@iu.edu

_________________________________________________________________________________
This is the author's manuscript of the article published in final edited form as:
Glupker, L., Kula, K., Parks, E., Babler, W., Stewart, K., & Ghoneima, A. (2015). Three-dimensional computed
tomography analysis of airway volume changes between open and closed jaw positions. American Journal of
Orthodontics and Dentofacial Orthopedics, 147(4), 426–434. https://doi.org/10.1016/j.ajodo.2014.11.025

Three-Dimensional Computed Tomography Analysis of Airway Volume Changes Between
Open and Closed Jaw Positions
Abstract:
BACKGROUND: Airway dimensions are closely linked to the bone and soft tissue
cranio-facial anatomy. Reduction of the airway is seen with airway disorders and can cause
impairments to life. The purpose of this retrospective study was to determine whether changing
from open to closed jaw position affects the volume of the nasal cavity, nasopharynx,
oropharynx, soft palate, soft tissue thickness of the airway and most constricted area of the
airway. MATERIALS AND METHODS: Following reliability studies, this retrospective study
analyzed CBCT scans taken in both closed jaw and open jaw positions of 60 subjects who were
undergoing diagnosis and treatment of temporomandibular disorder. On each scan,
condyle/fossa measures, the volume of airway segments (nasal cavity, nasopharynx,
oropharynx), soft palate area, soft tissue thickness of the airway and the most constricted area of
the airway and its location were measured using Dolphin® imaging software version 11.5.
Differences between the two jaw positions were analyzed using paired t-tests, accepting p≤0.05
as significant. RESULTS: Significant changes in airway dimensions were found between closed
and open jaw positions. With jaw opening the nasopharynx volume increased, while oropharynx
volume decreased. Significant decreases were also found for measurements of Ba-Posterior
airway wall, CV2ia-Posterior airway wall, most constricted area, nasal cavity volume, and soft
palate area when the jaw was open. CONCLUSIONS: Changing jaw position significantly
affects airway dimensions.

2 
 

Introduction:
The upper human airway has two entrances, the nasal cavity and the oral cavity. They combine
in the area known as the pharynx. The pharynx consists of three sections: the nasopharynx,
oropharynx and laryngopharynx (Figure 1). The nasopharynx is the superior portion of the
pharynx that is posterior to the nasal cavity and located behind the soft palate.1 The oropharynx,
below the nasopharynx, acts as a digestive and respiratory conduit and extends to the epiglottis.
The laryngopharynx is that area of the pharynx caudual to the epiglottis.
Narrowing of the airway dimensions can lead to challenges in breathing. For example, the size
of pharyngeal and palatine tonsils, in the naso- and oropharynx, respectively, influences airway
dimensions. Respiratory diseases associated with edema/inflammation of soft tissue can cause
airway restriction and can decrease quality of life. Airway disorders commonly seen include
obstructive lung disorders, such as asthma or apneas that show collapse of soft tissue such as
obstructive sleep apnea, both showing a decrease in the volume or flow of air. Obstructive sleep
apnea (OSA) is defined as having 30 or more episodes of apnea, cessation of airflow for more
than 10 seconds, during a normal night of sleep (7 hours).2 OSA treatment by the orthodontist
can vary in invasiveness but all treatments have the aim of allowing continuous breathing
without the cessation of airflow experienced by OSA patients.3 Previous studies have shown that
open mouthed breathing can increase the severity risk of OSA during sleep.4,5 During prolonged
dental treatment, those with OSA may have an increased risk of detrimental airway changes
when their mouths are open.
Evaluation of the airway has become an important aspect in orthodontic treatment planning. The
initial orthodontic screening evaluation provides an excellent opportunity to identify symptoms
of airway disorders. Questions about snoring, interrupted sleep patterns, and daytime
3 
 

somnolence combined with imaging taken at the exam can give indications of possible sleep
disorders and support the need for a polysomnograph test for diagnosis.6 With or without a
diagnosis of OSA it is important to understand the changes that opening the mouth cause in the
airways dimensions.
Previous studies on dental patients have shown changes to the airway when patients have their
mouths opened with a mouth prop.7,8 It is important to understand what the jaw open position
does to the patient’s airway so that treatment can be adapted to the patient’s needs. Some
patients may need more breaks during treatment to keep their oxygen saturation higher. Even
though the CPAP is the “gold standard” in treatment, there are other treatment modalities that
can be used such as the use of dental appliances to improve airway function or advancing the
upper or lower jaw by orthognathic surgery. Most dental appliances aim to move the mandibular
jaw forward and open the airway. Studies have shown airway changes with both the mandibular
advancement splint and tongue stabilizing device. 9 We know that positioning the jaw forward
improves the airway, but in treating OSA patient’s with dental appliances is opening the jaw
beneficial or detrimental? It has been reported that head and jaw positions would significantly
affect the airway dimensions.8 However, comparing open jaw position to closed jaw position
and its influence on the airway dimensions using 3D CBCT imaging has not been previously
studied.
A few studies have previously evaluated the differences in airway between open and closed jaw
position. However, these were done in patients wearing rubber dams or using mouth props for
restorative dental procedures.7,8 The study by Iwatani et al had 20 adult subjects who were
imaged with MRI.8 They found that the oropharyngeal airway volume decreased significantly
with the mouth open but the retropalatal and hypopharyngeal areas were not significantly
4 
 

affected.8 The second study by Ito et al was done on 13 subjects and using lateral cephalograms,
except for one subject where a computed tomograph was taken.7 They reported a decrease in
upper airway sagittal diameter when using a mouth prop. Subjects also indicated increased
dyspnea when their mouth was maximally open.7 With the greater interest in airway disorders
and the estimated 80-90% of people with undiagnosed OSA having moderate-severe OSA, it is
important to understand the changes that occur when a patient fully opens their jaw.
Imaging methods to view the airway include cephalometric radiographs, CBCT, and Magnetic
Resonance Imaging (MRI). Lateral cephalometric radiographs were the only available method
before CBCT and MRIs. This method had the limitation of imaging a 3-dimensional structure in
2D. Volume and cross-sectional area were not able to be accurately assessed with lateral
cephalometric radiographs.10 Some additional limitations with lateral cephalometric radiographs
are image magnification/enlargement and distortion, structure overlap, limited identifiable
landmarks, and positioning problems.11 MRI was used to measure the airway 3-dimensionally
and to visualize ventilation differences in respiratory diseases.12 Studies have shown that both
CBCT and MRI imaging methods are accurate ways to measure the airway.13-15 However CBCT
offers an easier, quicker, and more accurate method to obtain a view of a patient’s airway than
MRI. 16 CBCT has been used for measuring airway in studies looking into changes related to
facial bony structure, developmental changes, before and after varying orthodontic treatments,
maxillofacial surgeries, treatment of TMD and cleft lip/palate patients. CBCT imaging is an
accurate way of visualizing the condyle and measuring condyle position and location.17,18
This retrospective radiographic study is an exploratory study to determine the effects of
mandibular positional changes on the upper airway dimensions.

5 
 

Materials/Methods:
Population and selection criteria:
Following university IRB approval, this retrospective study included 60 patients’ CBCT
images retrieved from the archive of the Indiana University School of Dentistry’s (IUSD) Oral
Pathology, Medicine and Radiology Department. Each subject had two 13.3 inch scans taken:
one in closed jaw position and one at maximum open position (some showing a limited field of
view due to jaw opening). Inclusion criteria for this study: 1. Patient age greater or equal to 18
years, 2. No previous orthognathic surgery, 3. Two CBCT images (closed/open) taken at same
session, 4. No airway pathology noted on radiology Cone Beam Report. The average age of the
subjects was 40 years, 4 months ± 17years, 8 months. All subjects were female.
Data collection and measurements:
CBCT images were downloaded into Dolphin® 3D imaging software version 11.5
(Patterson Dental Supply, Inc., Chatsworth, CA) and measured on the same computer and
monitor. All 60 patient’s CBCT’s were coded and information on age and gender recorded.
Then subject information was de-identified.
Because of the limited field of view (FOV), some of the 3D-CBCT images did not show
both maxillary and mandibular incisors. Because of this, the condyle/fossa relationship of the
jaw was used to determine the amount of opening by the amount of translation of the condylar
head along the articular eminence instead of measuring the vertical distances between the central
incisors of the maxilla and mandible. On views that show both condyle and incisors, the vertical
distance between the maxillary and mandibular incisors was also measured. Both the rotation
and translational movement along the articular eminence to the apex of the eminence lead to
6 
 

opening of the mouth.19 The magnitude of opening is based on the amount of rotation and the
amount of translation during mandibular movement.20

Both translation and rotation were

measured on both condyles in both open and closed radiographs. Translation was determined by
visually dividing the glenoid fossa into 6 sections: center of the fossa, ¼, ½, ¾, top of eminence,
and past eminence (Figure 2) and determining how far along the glenoid fossa the condyle has
translated.21 This view was obtained from a sagittal slice through the middle of both condylar
heads. Rotation was measured by taking five linear measurements from the glenoid fossa to
condyle. A sagittal slice through the middle of the condyles was obtained. Then a horizontal
plane was placed through the widest width of the condylar heads visible on the slice. Lines were
then drawn through mid-point of condylar head crossing at 45°, 90° and 135°. Five linear
measurements representing anterior, antero-superior, superior, postero-superior, and posterior
directions were taken from the fossa wall to the center of condyle (the intersection of the 5 lines)
(Figure 3). All images were oriented in the sagittal, axial and coronal planes before taking
measurements following methods used in previous airway studies.22 This allowed us to
determine changes in the condylar head position as the jaw opens.
The airway and soft tissue measurements taken on CBCTs in both open and closed jaws are
presented in Table I and Figures 4-7:22-24
Sample size:
Based on a prior study and assuming a correlation of 0.9 between the closed and open
measurements, the standard deviations of the differences between the closed and open
measurements were estimated to be 950 mm3 for nasopharynx volume, 3400 mm3 for
oropharynx volume, 4000 mm3 for total airway volume, and 50mm3 for most constricted area of

7 
 

the airway.22 With a sample size of 60 subjects, the study was designed to have 80% power to
detect differences between the closed and open image measurements of 350 mm3 for
nasopharynx volume, 1250 mm3 for oropharynx volume, 1470 mm3 for total airway volume, and
19 mm3 for most constricted airway.
Reliability Testing:
The primary investigator, L.G., performed reliability measures using 10 coded and
randomized CBCT’s on all parameters. These CBCT’s were coded and randomized by the
investigator’s mentor (A.G.). Thus, the investigator was blinded to the names of the subjects. In
two weeks, the same ten cases were re-traced in a new randomly assigned order determined by
A.G. The reliability was calculated with a goal that the intraclass correlation coefficient (ICC) ≥
0.80. This process was repeated until ICCs were ≥ 0.80.
Statistical Analysis:
The reliability data was analyzed using intraclass correlation coefficients (ICCs) and
Bland-Altman plots to assess the intra-examiner reliability. Summary statistics (mean, standard
deviation, standard error, range) were calculated for all measurements from both the closed and
open jaw positions. The differences between the measurements and the ratio of the
measurements for the two jaw positions were calculated and summarized. Comparisons between
the closed and open jaw position measurements were made using paired t-tests accepting p≤ 0.05
as significant. For measurements that were made on both the left and right sides, mixed-model
ANOVAs were used to evaluate whether the closed vs. open comparison was affected by side.
Pearson correlation coefficients were used to evaluate the associations among the airway

8 
 

parameters. Translation of the condyles was compared using Cochran-Mantel-Haenszel tests for
repeated ordered categorical data.
Results:
A correlation coefficient of >.80 was obtained for all reliability values except the anterosuperior condyle measurement which had too much variability to accept the readings.
Descriptive statistics for the measurements in the closed and open jaw positions and for the
differences (open-closed) are presented in Tables II and III. Statistically significant differences
were detected in multiple parameters between the groups (Table III). Measurements that
decreased in the open position compared to the closed position were basion - posterior airway
wall, CV2ia - posterior airway wall, most constricted area, nasal cavity volume, oropharynx
volume, and soft palate area, while nasopharynx volume and U1 tip - L1 tip increased (Table
III). The values of AA-posterior airway wall and soft palate length did not show any significant
differences. Statistics for each condyle measurement by side and jaw position are summarized
(Table IV). A summary of the condyle measurement statistics for the difference between the
closed and open jaw positions of each condyle measure is listed in Table V. Comparisons of
condyle positions shows the differences between the open and closed jaw positions with the open
position always significantly larger than closed (Table VI). This shows there was a change in
jaw position with the jaw open but no difference between right and left sides.
Correlation coefficients were calculated to evaluate the associations of the airway parameters to
the U1 tip-L1 tip and the position of the condyle. The U1 tip-L1 tip had strong positive
correlations with the posterior right and left condyle positions (r=0.81 and 0.82, respectively); all
other correlations with airway parameters were negligible (correlations between -0.20 and
9 
 

+0.25). Antero-superior left condyle position had weak negative correlation (r=-0.32) with AAposterior airway wall and antero-superior right condyle position had weak negative correlation
(r=-0.39) with soft palate length. All other correlations of the antero-superior, posterior, posterosuperior, and superior left and right condyle positions with the airway parameters were
negligible, between -0.27 and +0.29 (Table VII).
Discussion:
In the present study, we used CBCTs to look 3-dimensionally at the oropharynx changes
between closed and open jaw position. We also looked into changes to the nasopharynx, nasal
cavity and soft tissue changes for a more thorough investigation into changes that occur with
opening the jaw. Several studies have now used CBCTs to view and measure the airway
volume. 10,16,25 It has been found to be a reliable source for assessing airway dimensions. The
Dolphin® 3D imaging software version 11.5 has been shown to be accurate and it has been used
in numerous previous studies.10 A limitation with the study was that CBCTs were completed on
subjects that were undergoing TMD diagnosis and treatment. It is possible TMD symptoms may
cause the path of opening to differ from patients with no TMD symptoms; however, our data did
not show significant differences between right and left condyle movements. In our study, there
were not significant differences between the condyle movements between right and left sides.
The results demonstrated that opening the jaw causes significant increases in several parts
of the upper airway, whereas others decrease significantly. The oropharynx showed a
statistically significant decrease in volume matching the previous studies done by Iwatani and
Ito.7,8 Our study also showed a statistically significant increase in the nasopharynx volume. The
area of most constriction showed a significant decrease and tended to move into the oropharynx

10 
 

with opening of the jaw (Table VIII). Forty-nine of the subjects (82%) had the area of most
constriction in the oropharynx with the jaw open. 55% of subjects’ area of most constriction
stayed in the same portion of the airway. The only values not showing a significant change
between closed and open were AA-posterior airway wall and soft palate length. All other values
had a significant difference between open and closed jaw positions.
Out of all the measurements showing a significant difference between the two jaw
positions, only nasopharynx volume and U1 tip-L1 tip showed an increase in size with mouth
opening.

The other values showed an inverse relationship and became smaller when going

from closed to open jaw. This can be explained by the fact that as the patient opens his jaw, the
upper and lower incisor become farther apart and with opening the soft palate drops down and
shows an increase in length. With opening the tongue tends to drop posteriorly. This would
drop the tongue into the oropharynx/hypopharynx causing a decrease in oropharynx volume.
The nasopharynx volume could become larger with the lengthening of the soft palate. There was
decrease in soft tissue size for measures Basion to the posterior airway wall and CV2ia to the
posterior airway wall. This would lead to an increase in nasopharynx volume which was also
shown.
Condyle position was used to detect if there was a change in jaw position. In each value
antero-superior, posterior, postero-superior, superior there was a significant change between
closed and open jaw positions. There was no significant difference between right and left side
values. The anterior condyle value was only obtained for one scan because of the articular
eminence shape. For the posterior, postero-superior, superior, and antero-superior values, all
became larger with opening. This may be possible as the condyle translates and rotates
downward and forward with opening. The condyles were also shown to move forward and
11 
 

downward along the eminence with opening through the visual measure. With the jaw closed,
the majority of condyles were in the center of fossa position. After opening, the majority were at
¾ down the eminence. These changes show that the patients had a difference in jaw position
between with the mouth open. This means any airway changes shown are because of the change
in jaw position.
This study has shown that there are significant differences between open and closed jaw
positions. Further studies will be needed to determine if it is only valid at maximum opening or
if the oropharynx progressively decreases as the mouth opens. Further studies on oral devices
would be needed to determine the effect of vertical changes. If the same even occurs when
patients are supine and open their mouth for dental treatment, then dental treatment may be
negatively impacting the airway and in some patients’ treatment timing or positioning of the jaw
may need to be changed to accommodate the airway.
Conclusion:
There is a significant change in airway dimensions between open and closed jaw positions. The
nasopharynx volume increased with opening while the upper airway soft tissue thickness, nasal
cavity volume, oropharynx volume, most constricted area and soft palate area decreased. The
area of most constriction also appeared to move to the location of the oropharynx with opening
of the jaw or remain in its original position at the oropharynx.

12 
 

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Figure Legends 
 

Figure 1: Airway anatomy 

 

Figure 2: Condyle translation measured as distance traveled toward eminence. 

 
Figure 3: Linear condyle measurements closed jaw: anterior, antero‐superior, superior, postero‐
superior, and posterior. 
 
Figure 4:  Measurements closed jaw: airway measurements in green (A: nasal cavity; B: 
nasopharynx; C: oropharynx).  Area measurement in red (D: Soft palate).  Linear measurements in blue 
(E: soft palate; F: Ba‐posterior airway wall; G: AA‐posterior airway wall; H: CV2‐posterior airway wall). 
 
Figure 5:  Measurements open jaw: airway measurements in green (A: nasal cavity; B: 
nasopharynx; C: oropharynx).  Area measurement in red (D: Soft palate).  Linear measurements in blue 
(E: soft palate; F: Ba‐posterior airway wall; G: AA‐posterior airway wall; H: CV2‐posterior airway wall). 
 

Figure 6: Nasal cavity coronal boundary 

 
Figure 7:  3‐dimensional airway boundaries rendering.  A: Sagittal view of a. nasal cavity, b. 
nasopharynx, c. oropharynx.  B: Frontal view of a. nasal cavity, b. nasopharynx, c. oropharynx. 

15 
 

Tables
Table I: Definitions of anatomic areas
Table II: Summary Statistics for Each Measurement for open and closed jaw positions
Table III: Summary Statistics for Differences between open and closed jaw positions
Table IV: Summary statistics for each condyle measurement by side for open and closed
jaw positions
Table IV: Summary Statistics for Condyle Measurements Differences between open and
closed jaw positions
Table VI: Comparison of Condyle Positions
Table VII: Correlations of airway parameters with condyle positions
Table VIII: Area of most constriction
 

 

16 
 

Table I: Definitions of anatomic areas 

Anterior boundary

Posterior
boundary
line extending
from Sella point
(S) – Posterior
nasal spine
(PNS)

Superior
Inferior
boundary
boundary
Nasal cavity
line connecting the
line connecting
line extending
anterior nasal spine
Nasion or the
from the anterior
highest point on
(ANS) – the apex of
nasal spine
the nasal bone –
nasal bone 1mm
(ANS) –
inferior to edge of Posterior nasal
(Na)
field of view (Nm) spine (PNS)
– Sella point (S)
Nasal cavity coronal boundary: outline of nasal cavity in section containing maxillary first molar
bifurcation, starting at crista galli and running down to the nasal floor following sidewalls of right and
left nasal cavity
Nasopharynx
line extending from line extending
line extending
Sella point (S) –
from Sella point
from posterior
Posterior nasal spine (S) – tip of the
nasal spine
(PNS)
odontoid process
(PNS) – tip of
the odontoid
process
Oropharynx
the line extending
line extending
line extending
line extending
from posterior nasal from the tip of
from posterior
from posterior
spine (PNS) –
the odontoid
nasal spine (PNS) nasal spine
perpendicular
process –
– tip of the
(PNS) – tip of
dropping to line
anterior-inferior odontoid process the odontoid
parallel to ruler
border of C2
process
running through
anterior-inferior
border of C2
Soft-palate
Length: Length from PNS to the most posterior-inferior point of soft palate
Area: Confined by the area that starts and ends at PNS through the uvula tip
Soft Tissue Measurements
AA point to the posterior airway wall
CV2ia most inferior-anterior point of CV2 to the posterior airway wall
Basion to the posterior airway wall
Most constricted area of airway
 

17 
 

Table II. Summary statistics for each measurement for open and closed jaw positions.
Measurement
AA-posterior airway wall (mm)
Basion - posterior airway wall (mm)
CV2ia - posterior airway wall (mm)
Most constricted area (mm2)
Nasal Cavity Volume (mm3)
Nasopharynx Volume (mm3)
Oropharynx Volume (mm3)
Soft palate area (mm2)
Soft palate length (mm)
U1 tip - L1 tip (mm)

Open/Closed
Closed
Open
Closed
Open
Closed
Open
Closed
Open
Closed
Open
Closed
Open
Closed
Open
Closed
Open
Closed
Open
Closed
Open

N
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
57

Mean
3.37
3.32
16.95
16.61
3.94
3.68
177.11
112.05
16590
15487
7015
7556
11893
9893
286.94
272.09
37.88
38.68
-2.84
20.76

SD
1.57
1.53
3.65
3.59
0.89
1.10
79.49
59.48
4351
4182
1951
2007
4060
3499
49.24
50.24
4.35
4.15
1.99
8.13

Minimum
0.10
1.30
11.60
11.20
2.70
1.30
19.90
29.80
9440
6714
1926
1991
3209
3921
185.00
120.50
28.40
25.50
-7.20
5.20

Maximum
8.40
8.00
29.50
30.20
8.50
8.00
323.60
272.80
30230
26552
10873
11230
20110
17924
400.10
385.10
47.90
45.00
5.20
36.80

Table III. Summary statistics for the difference between open and closed jaw positions.
Measurement
AA-posterior airway wall (mm)
Basion - posterior airway wall (mm)
CV2ia - posterior airway wall (mm)
Most constricted area (mm2)
Nasal Cavity Volume (mm3)
Nasopharynx Volume (mm3)
Oropharynx Volume (mm3)
Soft palate area (mm2)
Soft palate length (mm)
U1 tip - L1 tip (mm)

N
60
60
60
60
60
60
60
60
60
57

Minimum
-1.60
-3.60
-2.30
-217.0
-5900
-2700
-10096
-190.7
-22.40
10.10

P value is significant at P ≤ .05

18 
 

Maximum
3.40
3.40
1.50
104.10
7010
2457
5322
75.20
10.40
39.20

Mean
difference
open-closed
-0.05
-0.34
-0.26
-65.06
-1103
542
-2000
-14.85
0.80
23.59

SD
0.88
1.11
0.82
68.78
2028
930
3005
43.93
4.30
8.15

P value
0.6597
0.0217
0.0173
<.0001
<.0001
<.0001
<.0001
0.0112
0.1536
<.0001

Table IV. Summary statistics for each condyle measurement by side for open and closed jaw
positions.
Measurement
Anterior (mm)

Antero-superior (mm)

Posterior (mm)

Postero-superior (mm)

Superior (mm)

Side Open/Closed N
left Closed
39
Open
1
right Closed
40
Open
1
left Closed
60
Open
34
right Closed
60
Open
37
left Closed
60
Open
60
right Closed
60
Open
60
left Closed
60
Open
60
right Closed
60
Open
60
left Closed
60
Open
56
right Closed
60
Open
57

Mean
7.78
9.00
8.05
11.40
5.55
6.20
5.67
6.16
7.24
16.91
7.29
16.46
5.59
11.55
5.74
11.80
5.72
7.11
5.84
7.13

SD
1.54
.
1.92
.
1.10
1.65
1.15
1.67
1.66
5.88
1.75
5.19
1.21
4.04
1.63
4.31
1.12
2.81
1.36
2.73

Minimum
5.10
9.00
4.80
11.40
3.60
2.20
3.70
4.00
3.90
5.20
4.00
6.20
3.30
4.40
2.80
4.60
3.50
2.20
3.30
4.10

Maximum
12.00
9.00
13.20
11.40
8.70
12.30
9.20
13.40
11.10
34.70
12.90
27.20
8.80
19.10
12.30
25.50
8.80
17.10
10.30
19.30

Table V. Summary statistics for the difference between open and closed jaw positions for each
condyle measurement by side. 
Measurement
Anterior (mm)
Antero-superior (mm)
Posterior (mm)
Postero-superior (mm)
Superior (mm)

Side
left
right
left
right
left
right
left
right
left
right

N
1
1
34
37
60
60
60
60
56
57

Minimum
0.00
-0.20
-2.50
-2.80
-0.30
0.10
-0.70
-1.60
-3.90
-2.70

Maximum
0.00
-0.20
6.70
6.30
23.60
20.60
13.30
13.40
9.90
11.80

Table VI. Comparison of condyle positions.
Measurement
Antero-superior (mm)
Posterior (mm)
Postero-superior (mm)
Superior (mm)

Comparison
left & right n.s.
Open > Closed
left & right n.s.
Open > Closed
left & right n.s.
Open > Closed
left & right n.s.
Open > Closed

Difference
-0.12
0.55
0.07
9.04
-0.15
6.00
-0.08
1.35

P value
0.2815
0.0094
0.7270
<.0001
0.3796
<.0001
0.5671
<.0001

P value is significant at P ≤ .05
19 
 

Mean
difference
open-closed
0.00
-0.20
0.77
0.44
9.67
9.17
5.96
6.06
1.40
1.27

SD
.
.
1.69
1.62
5.48
4.64
3.92
4.04
2.82
2.46

Table VII. Correlations of airway parameters with condyle positions.

Measurement
U1 tip – L1 tip
(mm)
AA-posterior
airway wall
(mm)
Basion posterior airway
wall (mm)
CV2ia - posterior
airway wall
(mm)
Most constricted
area (mm2)
Nasal Cavity
Volume (mm3)
Nasopharynx
Volume (mm3)
Oropharynx
Volume (mm3)
Soft palate area
(mm2)
Soft palate
length (mm)

U1 tip - AnteroPosteroAnteroPostero- Superior
L1 tip superior Posterior superior Superior superior Posterior superior
(mm)
(mm) (mm) left (mm) left (mm) left (mm) left (mm) right (mm) right (mm) right right
1.00

-0.07

0.81

0.12

0.09

0.09

0.82

0.24

-0.02

-0.20

-0.32

-0.14

0.16

0.09

-0.07

-0.22

-0.02

0.09

-0.19

-0.15

-0.05

0.10

-0.01

-0.09

-0.07

0.09

-0.17

0.15

-0.06

0.26

-0.10

0.21

-0.08

0.24

-0.11

0.06

-0.01

0.10

0.06

0.08

-0.18

0.24

0.08

0.02

-0.24

0.10

-0.03

0.02

-0.08

0.00

-0.05

0.07

0.04

0.06

0.20

-0.25

0.16

0.12

-0.08

-0.17

0.16

-0.01

0.02

0.25

0.10

0.27

0.06

-0.17

-0.13

0.29

0.12

-0.27

-0.21

0.03

-0.13

-0.10

-0.08

0.06

-0.09

-0.16

-0.02

-0.08

0.02

-0.15

-0.08

-0.04

-0.39

-0.09

-0.05

-0.03

Table VIII: Area of most constriction

20 
 

60
50
40
Closed

30

Open

20
10
0
Naso

Oral

Hypo

21 
 

Figures 
 

Nasal Cavity
Nasopharynx 

Soft Palate
Oropharynx 

 
Fig 1. Airway anatomy 
 
 
 
 
 
 
 
 

22 
 

 
 
 
 

Distal 
to 
center 

Condylar 
fossa 
1/4 
1/2
3/4
Apex of eminence

 
Fig 2. Condyle translation measured as distance traveled toward eminence. 
 
 
 
 
 
 
 
23 
 

 
 
 
 
 

 
Fig 3. Linear condyle measurements closed jaw: anterior, antero‐superior, superior, postero‐superior, 
and posterior. 
 

24 
 

 
Fig 4. Measurements closed jaw: airway measurements in green (A: nasal cavity; B: nasopharynx; C: 
oropharynx).  Area measurement in red (D: Soft palate).  Linear measurements in blue (E: soft palate; F: 
Ba‐posterior airway wall; G: AA‐posterior airway wall; H: CV2‐posterior airway wall). 

25 
 

  
Fig 5. Measurements open jaw: airway measurements in green (A: nasal cavity; B: nasopharynx; C: 
oropharynx).  Area measurement in red (D: Soft palate).  Linear measurements in blue (E: soft palate; F: 
Ba‐posterior airway wall; G: AA‐posterior airway wall; H: CV2‐posterior airway wall). 
 

 
Fig 6. Nasal cavity coronal boundary. 

26 
 

 

 
Fig 7. 3‐dimensional airway boundaries rendering.  A: Sagittal view of a. nasal cavity, b. nasopharynx, c. 
oropharynx.  B: Frontal view of a. nasal cavity, b. nasopharynx, c. oropharynx. 
 

27