effects of le fort i osteotomy on airway
TRANSCRIPT
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CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY
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Effects of Le Fort I Osteotomy onthe Nasopharyngeal Airway—6-Month
Follow-Up
*Depar
sgow, U
yPostgrllege, G
zMedic
sgow, U
xPostgrsgow, U
kConsusgow, U
{Professgow D
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Mohammed Almuzian, BDS, MScOrtho, MScHCA, DClinDentOrtho,*
Anas Almukhtar, BDS, MScOrtho,y Xiangyang Ju, BEng, PhD,zAli Al-Hiyali, BDS, MScOMFS,x Philip Benington, BDS, MSc,k
and Ashraf Ayoub, BDS, MDS, PhD{
717273
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Purpose: The literature discussing the impact of a single Le Fort I osteotomy on nasopharyngeal airwaysis limited. This study assessed the volumetric changes in the nasopharyngeal airway after a single Le Fort I
osteotomy and explored the correlation between these changes and 3-dimensional surgical movements of
the upper jaw.
Materials and Methods: This retrospective study was conducted in 40 patients who had undergone a
single Le Fort I (maxillary advancement with or without impaction) to correct Class III malocclusion from
maxillary hypoplasia. Preoperative (T1) and 6-month postoperative (T2) cone-beam computed tomo-
graphic (CBCT) scans of these patients were used for analysis. Maxillary surgical movements and volu-
metric changes in the nasopharyngeal airway were measured. The reproducibility of the measurements
was evaluated using paired t tests and intraclass correlation coefficients. The Wilcoxon test and Pearson
correlation coefficient were applied to evaluate the importance of volumetric changes in the nasopharyn-geal airway space and assess the correlations of these changes to the maxillary surgical movements.
Results: Six patients were excluded from the study owing to major differences (>5�) in their head andneck posture between the T1 and T2 CBCT scans. The errors of the repeated measurements were insig-
nificant (P > .05), with a high level of agreement (r = 0.99; P < .05) between the repeated digitization
of the landmarks. There was a statistically significant impact of a Le Fort I osteotomy on the right maxillary
sinus (decreased by 17.8%) and the lower retropalatal space (expanded by 17.3%; P < .05). The correlation
between the change in airway volume and the magnitude of surgical maxillary movements was moderate
(r = .4). Similarly, there was a moderate correlation between changes in the upper nasopharynx and those
in the hypopharynx.
Conclusion: The single Le Fort I osteotomy was found to increase the retroglossal airway volume. This
could be important for the treatment of obstructive sleep apnea in patients with maxillary deficiency.
A long-term follow-up assessment of a larger sample with a functional assessment of airwaywould be bene-
ficial to confirm these findings.� 2015 American Association of Oral and Maxillofacial Surgeons
J Oral Maxillofac Surg -:1-12, 2015
tment of Orthodontics, GlasgowDental Hospital & School,
K.
aduate Student, Glasgow University Medical School, MVLS
lasgow Dental Hospital & School, Glasgow, UK.
al Devices Unit, NHS Greater Glasgow and Clyde,
K.
aduate Student, Glasgow Dental Hospital & School,
K.
ltant Orthodontist, Glasgow Dental Hospital & School,
K.
sor, Department of Oral and Maxillofacial Surgery,
ental Hospital & School, Glasgow, UK.
Address correspondence and reprint requests to Dr Almuzian:
Department of Orthodontics, Glasgow Dental Hospital and School,
378 Sauchiehall Street, Glasgow, UK; e-mail: dr_muzian@hotmail.
com
Received February 23 2015
Accepted June 26 2015
� 2015 American Association of Oral and Maxillofacial Surgeons
0278-2391/15/00907-6
http://dx.doi.org/10.1016/j.joms.2015.06.172
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Table 1. POINTS AND LANDMARKS
Point Definition
A Deepest (most posterior) midline point on the curvature between the ANS and the prosthion
ANS Tip of the bony anterior nasal spine at the inferior margin of the piriform aperture in the midsagittal plane
(often used to define the anterior end of the palatal plane)
Ba Basion; most anterior inferior point on the margin of the foramen magnum in the midsagittal plane
C2 Second cervical vertebra
C2sp (or C2od) Superoposterior extremity of the odontoid process of the C2
C3ai Most anteroinferior point of the body of the third cervical vertebra
Cg Most superior point of the crista galli
Cv2ig Tangent point at the superoposterior extremity of the odontoid process of the C2
Cv2ip Most inferoposterior point on the body of the C2
Cv4ip Most inferoposterior point on the body of the fourth cervical vertebra
Cvod Most superior point of the odontoid process of C2
LOr Lowest point on the left inferior orbital margin
Lpo Most superior point of the outline of the left external auditory meatus (anatomic porion)
LtLtPtg Most posterior point of the left lateral pterygoid plate as viewed on the coronal section
Lzyg Most lateral point in the left frontozygomatic suture
N Nasion; junction of the nasal and frontal bones at the most posterior point on the curvature of the bridge
of the nose
PNS Most posterior point on the bony hard palate in the midsagittal plane
Pr Prosthion; most anterior inferior point of the alveolar bone crest of the maxillary incisors
ROr Lowest point on right inferior orbital margin
RtLtPtg Most posterior point of right lateral pterygoid plate as viewed in the coronal section
Rzyg Most lateral point in the right frontozygomatic suture
S Sella; center of the hypophyseal fossa (sella turcica)
So Midpoint of line between the sella and basion
Spip Most posterior point of the middle of the soft palate
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
2 LE FORT I OSTEOTOMYAND NASOPHARYNGEAL AIRWAY Q25
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The impact of corrective jaw surgery on the upper
airway spaces depends on the type of operation, the
amount and direction of the skeletal movements, anda patient’s age, gender, and variations. Mandibular
setback surgery results in a decrease in airway patency;
therefore, bimaxillary osteotomy is indicated for the
correction of large anteroposterior discrepancies.1-5
Rhinomanometric techniques to measure nasal airway
resistance have shown that maxillary impaction
increases alar width, with a subsequent decrease in
nasal airway resistance.6,7 Another study based on2-dimensional cephalometric analysis has proved that
maxillary advancement meaningfully increases dimen-
sions of the airway.8
The lack of information on the impact of a Le Fort I
osteotomy on 3-dimensional measurements of the
nasopharyngeal airway inspired this study.
The study assessed assess volumetric changes in the
nasal cavity, maxillary sinus, and oropharyngeal airwayafter a Le Fort I osteotomy and investigated the corre-
lation between these changes and surgical maxil-
lary movements.
Materials and Methods
The sample size for this study was calculated using
the Researcher’s Tool Kit Calculator, which indicated
FLA 5.2.0 DTD � YJOMS56897_proof �
that a cohort of 32 patients would produce a confi-
dence level of 95% and a statistical power of 50%.
Therefore, it was decided to recruit 40 patients toovercome the potential exclusion of some cases. The
study was approved by the West of Scotland Qresearch
ethics service (reference, 12/WS/0133). The inclusion
criteria were as follows:
1. Caucasianmale and female patients 16 to 45 years
old who had a Le Fort I osteotomy (maxillary
advancement with or without impaction) to cor-
rect the underlying Class III malocclusion.
2. No previous tonsillar, nasal, adenoid, head or
neck surgery.
3. Nomajor variation in the head and craniocervical
orientation between the preoperative (T1) and
postoperative (T2) cone-beam computed tomo-
graphic (CBCT) scans.
4. No previous orthodontic expansion or mandib-
ular orthognathic surgical procedure.
Surgerywas carried out by the same surgeon and the
orthodontic treatment was carried out by various clini-
cians, ranging from consultants to specialist trainees,
in the Glasgow Dental Hospital and School (GDHS;Glasgow, UK). All patients underwent presurgical
15 July 2015 � 8:55 pm � CE AH
Table 3. CEPHALOMETRIC ANGLES
Angle Definition
Lordosis Measured by the mean of the SN-PAL and CVT-NS angles (Fig 1A)
Pitch angle (P angle) Inner angle of the intersection of the SN and TH planes; represents the change in head
orientation in the sagittal plane (cranial base inclination angle; Fig 1A)
Roll angle (R angle) Inner angle of the intersection of the Z and TH planes; represents change in head orientation in
the frontal plane (Fig 1B)
Yaw angle (Y angle) Represents change in head orientation in the mediolateral plane, measured by right (Cg-Cvod-
RtLtPtg)and left (Cg-Cvod-LtPtg) angles (Fig 1C)
Abbreviations: Cg-Cvod-LtLtPtg, angle formed by the most superior point of the crista galli, the most superior point of the odon-toid process of the second cervical vertebra, and the most posterior point of the left lateral pterygoid plate as viewed in the cor-onal section; Cg-Cvod-RtLtPtg, angle formed by the most superior point of the crista galli, the most superior point of the odontoidprocess of the second cervical vertebra, and the most posterior point of the right lateral pterygoid plate as viewed in the coronalsection; CVT-NS angle, angle formed by the line through and tangent to the superoposterior extremity of the odontoid process ofthe second cervical vertebra and the line connecting the nasion to the sella; SN-PAL angle, angle formed by the line connecting thesella and nasion and the line through the tangent point at the superoposterior extremity of the odontoid process of and the mostinferoposterior point on the body of the second cervical vertebra; TH plane, true horizontal plane; Z plane, zygomatic plane. Q3
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
Table 2. LINES AND PLANES
Line and Plane Definition
ANSV plane Perpendicular plane to true horizontal plane passing through the nasion in the lateral view; if the
midpalatine split extends to involve the anterior nasal spine, then the most posterior anterior nasal
spine is considered
C2sp/V plane Defined by the frontal plane perpendicular to the Frankfort horizontal plane passing through the
superoposterior extremity of the odontoid process of the second cervical vertebra
C3ai/H plane Plane parallel to the Frankfort horizontal plane passing through the most anteroinferior point of the body
of the third cervical vertebra
Cg-Cvod plane Line connecting the crista galli and the superoposterior extremity of the odontoid process of the second
cervical vertebra
CVT plane Line passing through the tangent point at the superoposterior extremity of the odontoid process of the
second cervical vertebra and tangent to the superoposterior extremity of the odontoid process of the
second cervical vertebra
Epi/FH plane Plane parallel to the Frankfort horizontal plane connecting the base of the epiglottis to the entrance of the
esophagus; technically by the plane parallel to the Frankfort horizontal plane connecting the base of the
epiglottis to the most anteroinferior point of the body of the fourth cervical vertebra (C4ai/H plane)
LF plane Left Frankfort; line connecting left orbit and left porionQ2 points
LOrH plane True horizontal plane tangent to the lowest point on the left inferior orbital margin
Orbital plane Line connecting right orbit and left orbit
PAL Line through the tangent point at the superoposterior extremity of the odontoid process of the second
cervical vertebra and the most inferoposterior point on the body of the second cervical vertebra
PNSH plane Plane parallel to the Frankfort horizontal plane passing through the posterior nasal spine and extending to
the posterior wall of the pharynx
PNSV plane Perpendicular to true horizontal plane passing through the posterior nasal spine; if the midpalatine split
extends to involve the posterior nasal spine, then the most posterior end of the palate is considered
PNSV plane True vertical plane passing through the posterior nasal spine
Ptg plane Line connecting the most posterior points of the left and right lateral pterygoid plate as viewed in the
coronal section
SN plane Plane representing a line connecting the sella to the nasion
Spip/FH plane Plane parallel to the Frankfort horizontal plane passing through the most posterior point of the middle of
the soft palate
SPPFH plane Sagittal plane perpendicular to the Frankfort horizontal plane passing through the lateral walls of the
maxillary sinus
TH plane True horizontal; a reference line constructed by drawing a line perpendicular to the true vertical line
TV plane True vertical; a reference line constructed perpendicular to the floor
Z plane Zygomatic; line connecting the most lateral points on the right and left frontozygomatic suture
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
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FIGURE1. Head and craniocervical orientation angles.A, Pitch and lordosis angle. B, Roll angle.C, Yaw angle. CVT-NS angle, angle formedby the line through and tangent to the superoposterior extremity of the odontoid process of the second cervical vertebra and the line connectingthe nasion to the sella; P angle, pitch angle; R angle, roll angle; SN-PAL angle, angle formed by the line connecting the sella and nasion and theline through the tangent point at the superoposterior extremity of the odontoid process of and the most inferoposterior point on the body of thesecond cervical vertebra; Y angle, yaw angle. Q1
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
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4 LE FORT I OSTEOTOMYAND NASOPHARYNGEAL AIRWAY
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FIGURE 2. Standardized orientation technique.
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
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orthodontic treatment using upper and lower fixed
appliances, with or without dental extractions.
Two CBCT scans were acquired for each patient:
immediately before the Le Fort I osteotomy (T1) and6 months after surgery (during or after orthodontic
FIGURE 3. Superimposition o
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Ora
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treatment; T2). All CBCT scans were taken at the
GDHS using an iCAT scanner (Imaging Sciences Inter-
national, Hatfield, PA) by a trained radiographer.
Patients were required to take off any spectacles orjewelry, keep their eyes gently closed, and keep their
n cranial-base technique.
l Maxillofac Surg 2015.
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Table 4. ANATOMIC BOUNDARIES OF AIRWAY SPACES15-18
Volume of Interest
Boundaries
Anteriorly Posteriorly Superiorly Inferiorly Medially Laterally
Lower nasal cavity NSV plane PNSV plane LOrH plane Inferior nasal wall Nasal septum Lateral nasal wall
Upper nasopharynx PNSV plane C2sp/V plane LOrH plane PNSH plane N/A SPPFH
Upper oropharynx PNSV plane C2sp/V plane PNSH plane Spip/FH plane N/A SPPFH
Retroglossal space PNSV plane C2sp/V plane Spip/FH plane C3ai/H plane N/A SPPFH
Hypopharynx PNSV plane C2sp/V plane C3ai/H plane Epi/FH plane N/A SPPFH
Maxillary sinus*
Abbreviations: C2sp/V, frontal plane perpendicular to the Frankfort horizontal plane passing through the superoposterior extrem-ity of the odontoid process of the second cervical vertebra; C3ai/H, plane parallel to the Frankfort horizontal plane passingthrough the most anteroinferior point of the body of the third cervical vertebra; Epi/FH, plane parallel to the Frankfort horizontalplane connecting the base of the epiglottis to the entrance of the esophagus; LOrH, true horizontal plane tangent to the lowestpoint on the left inferior orbital margin; N/A, not applicable; NSV, true horizontal plane passing through the posterior nasal spine;PNSH, plane parallel to Frankfort horizontal plane passing through the posterior nasal spine and extending to the posteriorwall ofthe pharynx; PNSV, perpendicular to true horizontal plane passing through the posterior nasal spine (if the midpalatine split ex-tends to involve the posterior nasal spine, then the most posterior end of the palate is considered); Spip/FH, plane parallel to theFrankfort horizontal plane passing through themost posterior point of the middle of the soft palate; SPPFH, sagittal plane perpen-dicular to the Frankfort horizontal plane passing through the lateral walls of the maxillary sinus.* All sinus cavities were included to the level of the LOrH plane superiorly and their minimum constricted openings with the
adjacent nasal and paranasal cavities circumferentially.
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
6 LE FORT I OSTEOTOMYAND NASOPHARYNGEAL AIRWAY
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teeth in centric occlusion. They also were instructed
to keep their lips and tongue in a normal relaxed posi-
tion during the scan. For each scan, the patient waspositioned with the Frankfort plane parallel to the
floor (natural head position).9 An extended field of
view of 22 cm was used to capture the facial skeleton
from the glabella to the angle between the chin and
the throat.
The Digital Imaging and Communications in Medi-
cine (DICOM) data for the T1 and T2 CBCT scans
were imported and displayed using OnDemand3Dsoftware (Cybermed Inc, Seoul, Korea). Based on the
reported validity of 3-dimensional cephalometric as-
sessments,10,11 the head posture and craniocervical
inclination (lordosis) were measured on each CBCT
scan taken at T1 and T2. Points, planes, and angles
used in this study are presented in Tables 1 to 3 and
Figure 1. Four angular measurements (pitch, roll,
yaw, and craniocervical angle) were recorded to thenearest degree. The first 3 angular measurements
correspond to head posture and the latter measure-
ment corresponds to lordosis. Patients were excluded
if the change in head posture or lordosis was greater
than 5� between the T1 and T2 scans, because such
changes have an important influence on nasopharyn-
geal airway measurements.12-14
Each T1 CBCT scan was digitally oriented so that theplane of the pterygoid plate, left Frankfort horizontal
plane, and zygomatic plane were parallel to the true
horizontal plane, and the data were saved as a new
T1 (NT1) scan (Fig 2). The T2 CBCT scan was superim-
posed on the corresponding NT1 scan, using the ante-
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rior and posterior cranial bases as stable structures,
and saved as a new T2 (NT2) scan (Fig 3). This allowed
a standardized segmentation and eliminated the effectof positional error on segmentation.
Using theNT1 andNT2 scans, the airway boundaries
were determined, segmented, and measured using the
ITK-SNAP software package (http://www.itksnap.org;
Table 4, Fig 4).15-18 QThemanufacturer’s instructions for
use of the ITK software package was followed.19 The
measurement of the volume of the lower nasal cavity
was limited to the respiratory space of the nasal cavityto minimize the inclusion of the paranasal sinuses and
their related hiatuses. The retropalatal spacewas subdi-
vided into upper (URP) and lower (LRP) retropalatal
spaces by the frontal plane perpendicular to the Frank-
fort horizontal plane passing through the superoposte-
rior extremity of the odontoid process of the second
cervical vertebra (C2sp/V plane). If the odontoid pro-
cess of the second cervical vertebra was located supe-rior to the C2sp/V plane, then the entire segment was
considered part of the LRP space.15,16,20 Regarding the
inferior boundaries of the hypopharynx (HP) space, if
the epiglottis was positioned halfway across the HP,
then a second volume measurement was added to
include this area or volume within the region of
interest. All volumetric measurements were carried
out by 1 examiner and repeated after 1 week, and the2 sets of measurements were compared to validate
the reproducibility of the landmarks used for
segmentation of the airway space boundaries.
The magnitude of the maxillary skeletal movements
was measured using the Maxilim software package
15 July 2015 � 8:55 pm � CE AH
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FIGURE 4. Airway space volumetric measurement and segmentation using ITK-SNAP. A, Saggital view. B, Coronal view. (Fig 4 continuedon next page.)
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
ALMUZIAN ET AL 7
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(Medicim NV, Mechelen, Belgium). Several markers
were identified and digitized directly on the DICOM
slices of the NT1 and NT2 scans. For maxillary surgical
movements, orthogonal distances were recorded to
the 3 common reference planes. The net movements
were calculated as the differences between the NT1
and NT2 landmark positions in the X, Y, and Z planes
(Fig 5).
STATISTICAL ANALYSIS
The distribution of the sample data was assessed
using the Kolmogorov-Smirnov test, which showed
non-Gaussian distribution for most parameters. The
Friedman test and Wilcoxon rank sum test (P < .05)were applied to determine a statistical difference
owing to age or gender and to evaluate the importance
of volumetric changes in the nasopharyngeal spaces
secondary to a Le Fort I osteotomy.
FLA 5.2.0 DTD � YJOMS56897_proof �
The Pearson correlation coefficient was applied to
assess the correlation between volumetric changes
and the magnitude of surgical maxillary movement
in 3 planes of space as a result of a Le Fort I osteotomy.
Results
Six patients were excluded from the study because
of a major difference ($5�) in head and neck posture
between the T1 and T2 CBCT scans. There was no sta-
tistically significant difference between the repeated
volumetric measurements (P > .05), with a high level
of agreement (r = 0.99; P < .05; Table 5).
The main surgical movement of the maxilla was ananterior shift of 6.42 � 1.51 mm (range, 3.43 to
8.5 mm). This also was associated with a mild vertical
impaction of 0.65� 0.28 mm (range, 0.07 to 2.27 mm)
more on the right side (mean, 0.82 � 0.32 mm; range,
15 July 2015 � 8:55 pm � CE AH
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web4C=FPO
FIGURE 4 (cont’d). C, Axial view. D, Virtual model representation of nasopharyngeal airway spaces.
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
8 LE FORT I OSTEOTOMYAND NASOPHARYNGEAL AIRWAY
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0.1 to 2.9 mm) than on the left side (mean, 0.47 �0.24 mm; range, 0.03 to 1.63 mm), with a mild medio-
lateral rotation of 0.86 � 0.44 mm (range, 0.2 to1.73 mm; Table 6).
Table 7 presents the volumetric changes of the naso-
pharyngeal airway spaces secondary to a Le Fort I
Osteotomy. The right maxillary sinus (RMS) was signif-
icantly decreased by 17.8%, whereas the LRP was
significantly expanded by 17.3% (P < .05). Gender-
related changes were not detected in this study (Fried-
man test, P = .4452).The correlation between the change in the volume
of airway space and the magnitude of surgical maxil-
lary movements was mild (r = 0.4; Table 8). Similarly,
there was a weak correlation between the volumetric
changes at different levels of the nasopharyngeal
FLA 5.2.0 DTD � YJOMS56897_proof �
airway space, except between the upper nasopharynx
(UNP) and the URP (correlation coefficient,
Q0.53; Table 9).
Discussion
This study relied on an internal reference structure
during segmentation that would not be affected by
occlusal settling or orthodontic movement between
the T1 and T2 CBCT scans. This is one of the explana-
tions for the differences between the results of this
study and other published data that have relied ondental reference points.17 Park et al17 used cervical
vertebral levels to subdivide the airway space, but
this was prone to errors because it relied on the pa-
tient’s head and neck posture during CBCT scanning.
15 July 2015 � 8:55 pm � CE AH
19
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FIGURE 5. Skeletal movement measurement using Maxilim software.
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
ALMUZIAN ET AL 9
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Changes in the head and neck posture owing to the ef-fect of surgery or projectional scanning errors would
affect the pharyngeal airway volume and cross-
sectional measurements.12,21-23 This source of error
was detected in this study by measuring the angles
of head orientation and neck lordosis at T1 and T2;
approximately 10% of patients showed major
changes in head and neck posture and were excluded.
This study used 2 distinguishing methodologies.First, it assessed the effects of a single Le Fort I osteot-
omy on the nasopharyngeal airway space. Second, seg-
mentation of the nasopharyngeal space allowed
Table 5. REPRODUCIBILITY OF VOLUMETRIC MEASUREMENTS
LMS RMS LNC
Wilcoxon signed rank test,
P < .05
0.742 0.945 0.43
ICC 0.999 1.000 0.99
Abbreviations: HP, hypopharynx; ICC, intraclass correlation coefretropalatal space; RG, ---; RMS, right maxillary sinus; UNP, u
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Ora
FLA 5.2.0 DTD � YJOMS56897_proof �
changes at different levels to be quantified becauseeach anatomic segment is related to a specific prob-
lem. Hern�andez-Alfaro et al16 Qfound a statistical expan-
sion in total pharyngeal airway space (37.7%). This is
dissimilar from the findings of the present study,
which could be due to the fact that the entire airway
space was considered and measured as a single unit,
rather than in segments. With regard to volumetric
changes in levels of the nasal cavity, the LNC Qwasdecreased by one tenth of its preoperative volume.
This could be due to the combined maxillary vertical
impaction, which decreases the effective volume of
UNP URP LRP RG HP
8 0.156 0.375 0.250 0.383 0.844
9 1.000 1.000 1.000 1.000 1.000
ficient; LMS, left maxillary sinus; LNC, ---; LRP, lowerpper nasopharynx; URP, upper retropalatal space. Q4
l Maxillofac Surg 2015.
15 July 2015 � 8:55 pm � CE AH
997
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Q21
Table 6. DEGREE OF MAXILLARY SURGICALMOVEMENTS
Mean SD Minimum Maximum
Net anteroposterior
movement
6.42 1.51 3.43 8.5
Net vertical movement 0.65 0.28 0.07 2.27
Right-side vertical
movement
0.82 0.32 0.1 2.9
Left-side vertical
movement
0.47 0.24 0.03 1.63
Net mediolateral
movement
0.86 0.44 0.2 1.73
Abbreviation: SD, standard deviation.
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway.J Oral Maxillofac Surg 2015.
Table 8. CORRELATION BETWEEN CHANGE INVOLUME OF AIRWAY SPACE AND MAGNITUDE OFSURGICAL SKELETAL MOVEMENT
Anteroposterior
Movement
Vertical
Movement
Mediolateral
Movement
LMS 0.020 0.014 0.040
RMS 0.039 0.030 0.030
LNC �0.128 �0.100 �0.041
UNP 0.018 �0.082 �0.069
URP 0.053 0.047 0.022
LRP �0.044 �0.104 �0.088
RG �0.12 �0.184 �0.226
HP 0.032 0.007 0.025
Abbreviations: HP, hypopharynx; LMS, left maxillary sinus;LNC, ---; LRP, lower retropalatal space; RG, ---;RMS, right maxillary sinus; UNP, upper nasopharynx; URP,upper retropalatal space. Q6
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway.J Oral Maxillofac Surg 2015.
10 LE FORT I OSTEOTOMYAND NASOPHARYNGEAL AIRWAY
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the LNC and disguises the effect of maxillary advance-
ment. Although the changes were not statistically
meaningful, they were similar to the findings of Pour-
danesh et al.23
The ratio of the RG space at T1 to T2 was approxi-
mately 4:6, with approximately 15% of volumetric
expansion after the Le Fort I osteotomy. An anatomi-
cally based explanation is that the superior attach-ments of the palatoglossus muscle were displaced
anteriorly secondary to maxillary advancement with
subsequent anterior displacement of the tongue and
expansion of the RG airway volume.24 Because the
main pathophysiology of obstructive sleep apnea and
hypopnea (OSAH) is that the tongue falls backward
and blocks the RG airway space during sleep, the Le
Fort I osteotomy might be an alternative option fortreatment of OSAH in patients with maxillary
hypoplasia.
Moreover, there was a decrease in the volume of the
2 maxillary sinuses, specifically the volume of the
Table 7. VOLUMETRIC CHANGES IN NASOPHARYNGEAL AIR
Airway Space
T1 T2
Mean SD Mean SD
LMS 9,705.6 2,482.1 9,511.7 2,468.2
RMS 10,471.6 3,488.6 8,606.2 3,427.4
LNC 7,917.2 1,452.5 7,189.2 2,306.7
UNC 6,640.2 2,661.6 7,311.7 2,434.1
RG 2,000.7 3,227.0 1,704.6 2,091.0
URP 8,534.1 7,738.0 9,053.8 4,039.1
LRP 8,605.2 4,684.9 10,089.6 5,590.3
HP 3,863.6 2,180.9 3,243.5 1,939.1
Abbreviations: HP, hypopharynx; LMS, left maxillary sinus; LNC,-maxillary sinus; SD, standard deviation; T1, preoperative; T2, 6 moURP, upper retropalatal space.
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Ora
FLA 5.2.0 DTD � YJOMS56897_proof �
RMS, which was decreased to one fifth of its preoper-
ative value. This can be explained by the differential
impaction of the right and left sides of the maxilla to
correct occlusal canting as a result of the dominance
of the right facial half.25-28 This assumption requiresa larger sample in which a Le Fort I osteotomy is
performed to correct the underlying asymmetry.
Although the main objective of the study was to
assess the impact of Le Fort I maxillary advancement
on the nasopharyngeal airway, minor simultaneous
surgical movements in the vertical or medial and
vertical directions were unavoidable.
The study showed a weak correlation between thevolumetric changes at different levels of the upper
airway tract and the magnitude of maxillary surgical
movement. However, there was a moderate positive
correlation between changes in the volume of the
WAY SPACES SECONDARY TO LE FORT I OSTEOTOMY
Percentage of Volumetric
Changes, (T2 � T1)/T1 � 100
Wilcoxon Signed Rank
Test, P < .05
�2.0 .408
�17.8 .015
�9.2 .109
10.1 .162
14.8 .5186
6.1 .1627
17.3 .013
�16.1 .501
--; LRP, lower retropalatal space; RG,---; RMS, rightnths postoperative; UNC,---; UNP, upper nasopharynx;
Q5
l Maxillofac Surg 2015.
15 July 2015 � 8:55 pm � CE AH
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Table 9. CORRELATION BETWEEN VOLUMETRIC CHANGES AT DIFFERENT LEVELS OF THE UPPER AIRWAY TRACT
LMS RMS LNC UNP URP LRP RG HP
LMS 1.000
RMS 0.073 1.000
LNC 0.145 0.040 1.000
UNP 0.084 0.384 0.063 1.000
URP �0.333 0.336 0.218 0.532 1.000
LRP 0.350 0.073 0.009 0.326 �0.114 1.000
RG �0.398 �0.137 �0.036 0.205 0.362 �0.038 1.000
HP 0.013 0.167 0.145 0.419 0.151 0.301 0.008 1.000
Abbreviations: HP, hypopharynx; LMS, left maxillary sinus; LNC,---; LRP, lower retropalatal space; RG,---; RMS, rightmaxillary sinus; UNP, upper nasopharynx; URP, upper retropalatal space. Q7
Almuzian et al. Le Fort I Osteotomy and Nasopharyngeal Airway. J Oral Maxillofac Surg 2015.
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UNP and URP spaces, which is due to the close
anatomic relation of these airway spaces. These find-
ings differ from those of Sears et al,18 probably becausethe design of the present study was limited to cases
that had a Le Fort I osteotomy only.
Although the outcomes of this study showed that
the applied technique in quantifying the airway vol-
ume was sensitive and reliable, its specificity in
measuring airway functionality needs to be assessed
clinically. The authors acknowledge that one of the
limitations of this study is the short-term follow-up,which was limited to 6 months after surgery. A future
comparative clinical study with long-term follow-up
would be beneficial to support changes in the naso-
pharyngeal airway spaces after a Le Fort I osteotomy.
Further applications of the ITK-SNAP software pack-
age could be used to gauge the size of the bony cleft
defect and the success of alveolar bone grafting in pa-
tients with cleft lip and roof of the mouth.The Le Fort I osteotomy was found to increase the
retroglossal airway volume and the right maxillary
antrum. This could be important for the treatment of
OSAH in patients with maxillary deficiency. A long-
term follow-up study in a larger samplewith functional
assessment of the airway would be beneficial to
confirm these findings.
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