effects of le fort i osteotomy on airway

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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{
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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

1

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Delta:1_given name

Delta:1_surname

Delta:1_given name

Delta:1_surname

Delta:1_given name

Delta:1_surname

mailto:[email protected]

mailto:[email protected]

http://dx.doi.org/10.1016/j.joms.2015.06.172

Q11

12

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


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 3

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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



4 LE FORT I OSTEOTOMYAND NASOPHARYNGEAL AIRWAY

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FIGURE 2. Standardized orientation technique.


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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


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.

15 July 2015 � 8:55 pm � CE AH

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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.



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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-


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 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.


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

18

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FIGURE 4 (cont’d). C, Axial view. D, Virtual model representation of nasopharyngeal airway spaces.



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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


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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print&web4C=FPO

FIGURE 5. Skeletal movement measurement using Maxilim software.


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



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


15 July 2015 � 8:55 pm � CE AH

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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.


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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.



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


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


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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.

References

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effects of le fort i osteotomy on airway

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