A retrospective cephalometric study on upper airway spaces in different facial types
Sprenger et al. Progress in Orthodontics
A retrospective cephalometric study on upper airway spaces in different facial types
Roselaine Sprenger 2
Luciano Augusto Cano Martins 1
Júlio Cesar Bento dos Santos 0
Carolina Carmo de Menezes 0
Giovana Cherubini Venezian 0
Viviane Veroni Degan 0
0 Department of Orthodontics, Araras Dental School-UNIARARAS , Araras, SP , Brazil
1 Department of Radiology, Piracicaba Dental School, University of Campinas , Piracicaba, SP , Brazil
2 Araras Dental School-UNIARARAS , Araras, SP , Brazil
Background: Craniofacial growth pattern has been correlated with variations in size of the upper airway spaces. The objective of this study was to evaluate the nasopharyngeal, oropharyngeal, and hypopharyngeal airway spaces variations according to the craniofacial growth pattern, by comparing brachyfacial, mesofacial, and dolichofacial in Angle Class I individuals. Methods: To measure the spaces, 45 lateral teleradiographs were used and divided into 3 groups per the craniofacial growth pattern, determined by the Tweed cephalometry angular measurements: FMA and Y-axis. To evaluate the airways, sleep apnea cephalometry was used, containing 28 points that compose 14 factors. Three groups were compared relative to each of the 14 sleep apnea cephalometry measurements. Adherence test to the normal curve was performed. For the non-normally distributed data-measurement of the inferior pharyngeal space-the Kruskal-Wallis test was used for comparison between the groups. For the remaining data, the distribution was normal and ANOVA test was used. Results: Statistically significant difference was verified among the groups for the measurement of the median posterior-palatal space, with the difference being pointed out by the post hoc test between the brachyfacial and dolichofacial groups. For the other measurements, there was no statistically significant difference. Conclusions: It could be concluded that there was difference in the median posterior-palatal space measurement, in the oropharynx region, which was reduced for individuals with a dolichofacial pattern.
Orthodontics; Cephalometry; Nasopharynx; Oropharynx; Hypopharynx; Facial types
The upper airway is composed of the nasopharynx,
oropharynx, and hypopharynx. Pharyngeal space size is
determined primarily by the relative growth and size of the soft
tissues surrounding the dentofacial skeleton [
A normal upper airway improves nasal breathing and
is considered important in the growth and development
of craniofacial structures [
An obstructive upper airway is present when
obstructive processes of a morphological, physiological, or
pathological nature occur, such as hypertrophy of adenoids
and tonsils, chronic and allergic rhinitis, irritant
environmental factors, infections, congenital nasal deformities,
nasal traumas, polyps, and tumors cause functional
imbalance and result in oral breathing patterns [
The upper airway dimensions may be influenced by the
facial skeletal pattern, in which the relationship between
the position of the maxilla and mandible in the
anteroposterior direction has great influence on space [
There are studies in the literature about changes in
the upper airways resulting from orthodontic treatment,
orthognathic surgery or in individuals diagnosed with
sleep apnea [
]; however, few studies have shown
evidence of the airspace related to facial types and Angle
Class I individuals, and this information is relevant to
assist in orthodontic planning.
The aim of the present study was to evaluate the
nasopharyngeal, oropharyngeal, and hypopharyngeal airway
spaces in brachyfacial, mesofacial, and dolichofacial in
Angle Class I individuals.
Sample characteristics and data collection
The sample size calculation for the difference between
two measurements was made considering the test power
of 80 and 95% confidence coefficient. The values with
reference to the mean and standard deviation of the
variable median posterior palatal space when compared
with two independent groups, and the estimate of the
minimum difference to be detected, required for the
calculation, were retrieved from the previous results [
The sample was composed of 45 digital lateral head
teleradiographs of adult individuals, with permanent
dentition, skeletal Class I determined by Steiner’s variable ANB
], mean SNA of 82.65° (standard deviation = 1.94), and
SNB 81.11° (standard deviation 1.95).
Excluded from the study were teleradiographs lacking
distinctness of structures in the image, previous history of
palatine tonsil and/or pharyngeal tonsil surgeries,
orthodontic treatment and/or orthognathic surgeries, volunteers
submitted to extractions, or those with dental agenesis.
Teleradiographs were obtained by using the same
equipment (Cranex D® Soredex Orion Corporation,
The cephalometric analyses were performed digitally by
means of the Radiocef Studio 2 program (Radiomemory
Ltda, MG, Brazil), using a resolution of 300 dpi for the
]. For this purpose, the radiographs were
digitized by a table scanner (Cranex D® Soredex Orion
Corporation, Tuusula, Finland) [
], coupled to a
transparency reader, using a resolution of 300 dpi, and
saved in TIFF format (Tagged Image File Format)
The measurements were performed by a single, blinded,
duly calibrated examiner. Intra-examiner reliability was
tested by re-doing 30% of the cephalometric analyses. Five
teleradiographs were randomly selected from each group,
totaling 15 teleradiographs of patients whose sleep apnea
cephalometries were repeated after 30 days.
The Tweed FMA [
] and Y-Axis measurements were
used to select the facial type. Teleradiographs were
randomly selected at a radiology center and classified
according to the FMA and Y-axis, and all
teleradiographs presented the same FMA measures and Y-axis
classification. The FMA measurement corresponded to
the angle between the mandibular plane (GoMe) and the
Frankfort plane (PoOr), and its reference value was 25°.
Values above 30° were considered a vertical growth trend
(dolichofacial); below 20°, a horizontal trend
(brachyfacial), and the Y-axis, also called the angle of facial growth,
formed by the sella-gnathion line and the Frankfort
horizontal plane intersection. The mean value was 59°. An
increase in this value indicated a vertical growth trend,
and a reduction, a horizontal growth trend [
Fifteen teleradiographs were selected of each
craniofacial growth pattern, classified into mesofacial (5 males
and 10 females, aged 16–31 years, mean age = 22.21),
brachyfacial (8 males and 7 females, aged 17–34 years,
mean age = 25.6), and dolichofacial patterns (11 male e 4
females, aged 16–31, mean age = 25.0). To evaluate the
upper airways, sleep apnea cephalometry, validated for
], was used, containing 28 points that
compose 14 factors (Figs. 1, 2, 3, 4, 5 and 6).
The groups were compared for each of the 14 factors.
For the inferior airway space measurement that
presented non normal distribution, the Kruskal-Wallis test
was used for inter-group comparison. For the remaining
data, whose distribution was normal, one-way ANOVA
followed by complementary Tukey tests was used. The
significance level was 5%.
Fig. 1 Factors for sleep apnea analysis
The Intraclass Correlation Coefficient (ICC) showed
excellent replicability (0.9636).
In the comparison of the three groups for each of the
14 sleep apnea cephalometric measures, statistically
significant difference was verified among the groups for the
median posterior palatal space (p = 0.020), with the
complementary Tukey test pointing out difference between
the brachyfacial and dolichofacial groups.
When the measurements presented in Table 1 were
analyzed, it was verified that the median posterior palatal
measurement in the oropharyngeal region was lower for
individuals with a dolichofacial (10.64 ± 1.83) pattern
when compared with mesofacial (12.64 ± 2.30) and
brachyfacial (12.91 ± 2.74) patterns.
For the other measurements, there was no statistically
significant difference (p > 0.05). However, for the
dolichofacial group, it was observed that on an average,
numerically, the inferior pharyngeal space measurements
(12.79 ± 4.72), atlas-maxilla distance (35.22 ± 3.25), and
posterior airway space (12.31 ± 2.86) were shown to
be smaller in comparison with those of the other
The contribution of this study was to present the use of
a cephalometric analysis, commonly used in
orthodontics, with the aim of identifying anatomical changes in
the upper airways, which may predispose to respiratory
Cephalometric performed by means of lateral
teleradiography has been shown to be an important
instrument in the multidisciplinary field for evaluating the
upper airways [
] because it is easily accessible and
low cost, highly reproducible, and the individual is
submitted to a low dose of radiation [
innumerable studies have sought associations of the
physical characteristics related to these airway spaces, as
a way of predicting pathologies [
However, there are studies that use computed
tomography for morphological evaluation of the airway spaces,
particularly due to the possibility of measuring areas and
volumes, which is impossible to do by means of other
radiographic exams [
]. Therefore, the authors
point out that one of the limitations of the present study
refer to not measuring the airway volumes, due to the
type of exam used for evaluation [
]. There was also
difficulty in the methodologies with two-dimensional
radiographs when performing superimposition of tracings
]; however, in the present study, no superimpositions
were made. Many studies have evaluated the airways by
using lateral cephalograms and associated their
dimensions with the vertical skeletal pattern of the face and
facial morphology [
1, 26, 27
]. A recent longitudinal study
also used lateral cephalometric radiographs for
associating changes in the morphology of the nasopharyngeal
space in different facial patterns [
], which did not
make this method of evaluation unfeasible.
In this study, the authors opted to use the sleep apnea
cephalometry instrument because it has been validated
for Brazilians and presents standard values that may be
used as reference [
The authors were able to identify reduction in the
median posterior palatal space in individuals with a
dolichofacial pattern. A previous study also observed
changes in the dimensions of the upper airway related to
the reduction in the medial posterior palatal space in
individuals with the obstructive sleep apnea syndrome
]. This measurement expresses the distance
from the soft palate to the posterior wall of the pharynx
and has a close relationship with the dimensions of the
soft palate. The increased length of which was related to
presence of OSAS in other researches [
8, 29, 30
] and the
present study. The highest alteration values in upper
airway dimensions in OSAS patients occur in the
] and were related to the reduction of the median
posterior palatal space [
]. In individuals with a vertical
pattern, the mandible is normally retracted and rotated
downwards and backwards, thus diminishing the
oropharyngeal space [
] Furthermore, the base of the
tongue accompanies the direction of mandibular
rotation, being positioned downward and backward, thus the
soft palate is in a more retrusive position, diminishing
the median posterior palatal space.
Some authors have pointed out that when the
nasopharyngeal space was reduced, there would be a tendency
towards neuromuscular adaptation, leading to vertical
growth of the face that is associated with a dolichofacial
]. However, in this study, no difference was
found in the upper airway dimensions in the
nasopharyngeal region in the studied volunteers with this
facial type. This could be attributed to different sample
characteristics in others studies in which the sample was
composed of the youngest participants [
]. This aged
group could be more susceptible to narrower
nasopharyngeal airway spaces due to adenotonsillar
hypertrophy, for example [
]. In addition, authors
 compared Angle Classes I and II, differently from the
present study, in which the sample was composed of only
Class I patients.
Obstruction of the upper airways forces the patient to
breathe through the mouth, and in addition to OSAS,
these factors cause oral dysfunction, such as lip
incompetence, low position of the tongue in the floor of the
mouth, tongue thrust, and may lead to unbalanced
muscle and function [
] disturbances in swallowing,
mastication, speech [
], and stability of occlusion [
This study was performed using two-dimensional
digital lateral cephalogram that is a limitation.
Therefore, it is important to recognize that three-dimensional
evaluation of the airways by means of cone-beam
computed tomography, respecting legal and ethical
aspects, due a higher dose of radiation, could be useful
for improved assessment in further studies to minimize
Under the conditions of this study and considering the
results, the authors could conclude that there were no
differences in nasopharyngeal and hypopharyngeal
airway spaces in brachyfacial and mesofacial individuals.
Oropharyngeal space reduction was observed in Angle
Class I dolichofacial individuals, characterized by
reduction in the median posterior palatal measurement.
RS, VVD, GCV, and CCdM conceived and designed the experiments. RS, GCV,
LACM, and JCS performed the experiment. GCV, CCdM, and VVD analyzed
the data. RS, GCV, LACM, and JBS contributed material/analysis tools. RS, VVD,
GCV, and CCdM wrote the manuscript. RS, VVD, GCV, LACM, and JCBS
prepared the figures and tables. VVD, GCV, and CCdM reviewed drafts of the
paper. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Ethics approval and consent to participate
This retrospective study was approved by the Research Ethics Committee of
the institution at which the study was conducted (no. 33799614.1.0000.5385).
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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