The Journal
the treatment, whereas the rest of the
oropharynx and hypopharynx remained
narrower than in the controls. Before the
treatment, the mandibular plane was in a more
horizontal position than in the controls, but
during the treatment, it rotated to a position
similar to that of the controls. Thus, Class II
division 1 malocclusion is associated with a
narrower upper airway structure even without
retrognathia. Headgear treatment is associated
with an increase in the retropalatal airway
space 49 .
Changes in the normal pattern of nasal
respiration can profoundly affect the
development of the craniofacial skeleton in both
humans and experimental animals (Neilsen;
2009). Results showed a moderately high
correlation between airway area and volume;
the larger the area, the larger the volume.
However, there was considerable variability in
the airway volumes of patients with relatively
similar airways on the lateral headfilms. Thus,
the cone-beam 3-dimensional scan is a simple
and effective method to accurately analyze the
51
airway .
Fig 11 : Maxillary protraction appliance (MPA)
Another study was done in 2008 by Oktay to test
the hypothesis that maxillary protraction
appliances (MPA) have no effect on the size of
the upper airway passage and craniofacial
structures in adolescent patients. Thus, the
hypothesis was rejected and it was seen that
the size of the upper airway can be increased by
means of MPA application 50 .
46
Upper airway size is increasingly recognized as
an important factor in malocclusion. However,
children with Class III malocclusion are
somewhat neglected compared with those with
a Class II skeletal pattern. Therefore a study
was done in 2009 by Iwaski to establish the
characteristic shape of the oropharyngeal
airway (OA) in children with Class III
malocclusion. Therefore, the Class III
malocclusion is associated with a large and flat
52
OA compared with the Class I malocclusion .
Vol. 14 No. 2
May-August 2018