The Journal
Palatal expansion often has been prescribed
as a means of enlarging the nasal airway.
53
Radiographic studies by Derichsweiler (1953),
55
and Korkhaus (1960) confirmed an increase in
the width of the pyriform aperture after palatal
56
expansion. Similarly, Gray and Brogan (1972)
expressed the belief that rapid palatal
expansion may be effective in improving nasal
airways in patients with septal deformity.
Accordingly, they recommended palatal
expansion as early as 3 to 7 years of age for
patients with clinically determined septal
deviation, even if no dental crossbite were
evident. None of these authors conducted
airflow studies or soft tissue measurements to
confirm their assumption of a nasorespiratory
benefit.
Recently, attention has been directed towards
the possible role of head posture on
morphogenesis. Earlier animal studies by
Losowski
and colleagues 8 (1961), Moss 8
8
(1968), and Riesenfeld (1966) demonstrated
that experimentally induced changes in
posture influence craniofacial morphology.
This issue is relevant to respirometric research
in that the spatial relationships between the
orofacial and craniocervical structures may
influence or be influenced by the mode of
respiration.
Solow 10 (1966, 1977) and Solow and
8
Tallgren (1971, 1976) described consistent
differences in dental and craniofacial skeletal
features in adult males between individuals with
"extended" and "flexed" natural head positions.
Posnick 9 (1978) duplicated their method and
found similar associations in children. In an
attempt to establish a causal link between the
observed morphologic and postural features,
Solow and Kreiborg 8 (1977) postulated what
has come to be known as the "soft-tissue
stretching hypothesis." This scheme involves
airway obstruction as a key link in chain of
events that they have combined to yield the
following cyclic argument. Although Vig,
48
Showfety, and Phillips 7 (1980) have
demonstrated total obstruction of the nares
induces extension of the head, this should be
constructed as validation of the "soft-tissue
stretching hypothesis."
The advent of computerized tomographic (CT)
scanning has enhanced the potential of
radiographs for the study of three-dimensional
objects. Using cadaver material, Montgomery
6
and colleagues (1979) found that the cross
sectional area of the airway could be
determined accurately at any point along the
length of the nasal passages. Because the
limiting factor that determines the capacity for
airflow is the minimum cross-sectional area of
the passage, this technical advance is
important. They found in their specimens that
the most constricted part of the airway was not
necessarily at the turbinates. One implication of
this observation is that orthodontic and/or
surgical techniques designed to widen the
palate or remove the turbinate may have little or
no effect on the points of greatest airflow
restriction and, as a result , no respiratory
benefit. This study also questioned the validity
of using anteroposterior radiographs as a
primary diagnostic measure of airway patency
by demonstrating the tortuous and anatomically
irregular nature of the nasal airway, which is
obscured on a routine frontal radiograph.
Despite the obvious shortcomings of both
frontal and lateral cephalograms, Holmberg
5
and Linder-Aronson (1979) recommended
their use for the diagnosis of nasal obstruction.
Unfortunately, their data are at variance with
their conclusions and do not support their
contention that “lateral and frontal skull
radiographs provide a satisfactory means of
evaluating the dimensions of the nasopharynx
and the capacity of the nasal airway,
respectively."
Using the pressure-flow data of Holmberg and
Linder-Aronson 5 (1979), Vig and Hall 4 (1980)
Vol. 14 No. 2
May-August 2018