SECTION 7: SELECTED SHORT COMMUNICATIONS

A three-dimensional

evaluation of the upper

airway in adolescents

CA Aboudara

D Hatcher

IL Nielsen

A Miller

Authors' affiliations:C.A. Aboudara, D. Hatcher, I.L. Nielsen,

A. Miller, Department of Growth and

Development, University of California,

Division of Orthodontics, San Francisco,

CA, USA

Correspondence to:

CA Aboudara

Univesity of California, San Francisco

Department of Growth and Development

Division of Orthodontics

707 Parnassus

San Francisco

CA 94143, USA

Tel.: +1 650 328 2860

E-mail: cabouda@itsa.ucsf.edu

Abstract

Authors – Aboudara CA, Hatcher D, Nielsen IL, Miller A

The link between the facial growth and airway function has been a

subject of controversy in orthodontics for many years. This study

investigates how well lateral cephalometric headfilms depict

three-dimensional upper airway structures. Subjects are 11

normal adolescent children, ages 7–16 years old. Airway infor-

mation over the same anatomic area in the nasopharynx is

compared between lateral cephalometric headfilms and three-

dimensional cone beam computed tomography (CT) scans.

Intra-subject proportion of airway volume to area shows moder-

ate variability. CT airway volume shows more variability than

corresponding headfilm airway area.

Key words: upper airway; orthodontic; three-dimensional;

cone beam computed tomography; NewTom

Introduction

Airway contributes to overall facial development.

Research has shown children undergoing adenoidec-

tomy had larger total and anterior face heights, more

retrognathic mandibles, and steeper mandibular planes

compared with controls. Children who switched back to

nose breathing showed some correction towards the

controls through decreasing mandibular plane angles,

proclination of the incisors, and widening of the upper

arch. Girls in the sample showed significantly more

horizontally growing mandibles over this period (1–4).

Studies of artificially induced nasal occlusion in mon-

keys have found different neuromuscular patterns of

adaptation with lowered mandibular posture, increased

To cite this article:

Orthod Craniofacial Res 6 (Suppl. 1), 2003; 173–175

Aboudara CA, Hatcher D, Nielsen IL, Miller A:

A three-dimensional evaluation of the upper

airway in adolescents

Copyright � Blackwell Munksgaard 2003

ISSN 1741-2420

posterior dental eruption, and forward tongue postures

that resolved once obstructions were removed (5, 6).

Currently during orthodontic diagnosis and treat-

ment planning, information on the airway is charted.

Enlarged tonsils and breathing patterns are often noted

on clinical examination. Adenoids are subjectively

quantified from examination of the two-dimensional

lateral cephalometric headfilm, but there have been few

studies on the three-dimensional airway of adolescents.

This pilot study is a retrospective cross-sectional

chart review which evaluates the two-dimensional air-

way from lateral headfilms and the three-dimensional

airway structure from computed tomography (CT)

scans.

Materials and methodsInclusion criteria

Children aged 5–17 years presenting for orthodontic,

oral pathology, or temporomandibular disorders diag-

nostic imaging. Required – lateral cephalometric

headfilm and conical CT scan at the same time point.

Exclusion criteria

Craniofacial anomalies, previous orthognathic surgery,

history of tonsillectomy or adenoidectomy, subjects

with postural orthodontic appliances (Table 1).

Lateral cephalometric X-rays

• All films taken with Instrumentarium� Orthopanto-

mograph OP100� (Instrumentarium Imaging,

Tuusala, Finland).

• All structures assumed at midline with magnification

of 9.8%.

• Films scanned at 300 dpi for analysis in 3-D Doctor�

(Able Software Corp., Lexington, MA, USA).

Fig. 1. Region of interest.

Table 2. Numeric results

Patient

CT volume

(mm3)

Ceph area

(mm2)

Proportion

(volume/area)

1 2561.6 320.4 8.0

2 1749.3 266.7 6.6

3 4180.7 407.6 10.3

4 3821.0 327.5 11.7

5 4499.8 389.1 11.6

6 3782.9 370.5 10.2

7 2896.0 224.8 12.9

8 3246.4 339.1 9.6

9 7839.3 472.2 16.6

10 2807.2 324.6 8.6

11 4921.2 312.2 15.8

Mean 3845.9 341.3 11.1

SD 1613.5 67.5 3.1

Table 1. Pilot patient data

Patient Age Sex Referral

1 16 years 1 month F TMJ

2 12 years 8 months M TMJ

3 15 years 11 months F TMJ

4 9 years 10 months F TMJ

5 14 years 6 months F TMJ

6 12 years 0 month F TMJ

7 7 years 7 months F Impacted nos 6 and 10

8 13 years 8 months F TMJ

9 12 years 6 months F TMJ

10 9 years 9 months F TMJ

11 14 years 6 months M TMJ

174 Orthod Craniofacial Res 6 (Suppl. 1), 2003/173–175

Aboudara et al. 3-D adolescent airway comparison

Cone beam CT scans

• Scans taken on NewTom-9000� developed by

Quantitative Radiology, Verona, Italy.

• Scan acquired in a 512 · 512 format. Voxel size is

0.28 mm in x, y and z planes of space.

• Digital imaging files exported in DICOM (Digital

Imaging and Communications in Medicine) format

for analysis in 3-D Doctor� (Able Software Corp.).

Region of interest

• Conical CT scans are taken in the supine position.

Previous research: significant differences in airway

measurements below the hard palate from lateral

headfilms taken in an upright and supine position (7).

• Comparison airway measurements will concentrate

in the nasopharynx superior to the hard palate.

• Boundaries: 1) axial reconstruction plane through

posterior nasal spine; 2) plane perpendicular to the

former at PNS to height of the pterygomaxillary

fissure; 3) posterior pharyngeal wall.

• Corresponding CT volume to lateral headfilm area

calculated from serial 1 mm axial sections. Variable

threshold segmentation used. Intra-subject pro-

portions of airway volume to area are compared

(Fig. 1).

Results (see Table 2 and Fig. 2)

• Intra-subject proportion of airway volume to area

shows moderate variability.

• Airway volume shows more variability than airway

area.

• There may be airway information that is not accu-

rately depicted on the lateral headfilm. More analysis

with a larger sample size is needed.

References1. Linder-Aronson S. Effects of adenoidectomy on dentition and

nasopharynx. Trans Eur Orthodontic Society 1972:177–86.

2. Linder-Aronson S, Woodside DG, Lundstrom A. Mandibular

growth direction following adenoidectomy. Am J Orthod

1986;89:273–84.

3. Linder-Aronson S, Woodside DG, Hellsing E, Emerson W.

Normalization of incisor position after adenoidectomy. Am J

Orthod Dentofacial Orthop 1993;103:412–27.

4. Woodside DG, Linder-Aronson S, McWilliam J. Mandibular and

maxillary growth after changed mode of breathing. Am J Orthod

Dentofacial Orthop 1991;100:1–18.

5. Miller AJ, Vargervik K, Chierici G. Experimentally induced

neuromuscular changes during and after nasal airway obstruction.

Am J Orthod 1984;85:385–92.

6. Vargervik K, Miller AJ, Chierici G, Harvold E, Tomer BS. Morpho-

logic response to changes in neuromuscular patterns experi-

mentally induced by altered modes of respiration. Am J Orthod

1984;85:115–24.

7. Battagel JM, Johal A, Smith AM, Kotecha B. Postural variation in

oropharyngeal dimensions in subjects with sleep disordered

breathing: a cephalometric study. Eur J Orthod 2002;24:263–76.

CT volume (mm3)

Ceph area (mm2)

mm3

mm20

2000

1000

8000

Fig. 2. Individual subject volume and area of nasopharyngeal

airway.

Aboudara et al. 3-D adolescent airway comparison

Orthod Craniofacial Res 6 (Suppl. 1), 2003/173–175 175