A Cephalometric Comparison of Pharynx and Soft palate in Subjects treated with Rapid Maxillary Expansion

The purpose of this study was: (1) to assess the cephalometric
variables of the nasopharynx, oropharynx and laryngopharynx
including soft palate among male and female subjects with different
anteroposterior jaw relationships, orthognathic and retrognathic,
treated with a rapid maxillary expander, a Hyrax-Type expansion
appliance, in two dimensions; (2) to assess the cephalometric
variables of the pharyngeal area in the control group; (3) to
compare the variables of both groups in order to investigate the
pharyngeal area. Seventy-one maxillary constriction subjects, 39
females and 32 males, were selected from the records section of the
Department of Orthodontics of the Ludwig Maximilian University,
Munich, on the basis of the following criteria: (1) patient with
skeletal maxillary constriction; (2) no observable craniofacial
abnormalities; (3) no previous orthodontic treatment; (4) first
permanent molars, primary molars or premolars were in occlusion;
and (5) each lateral cephalometric radiograph was taken with teeth
in centric occlusion. The RME group was compared with a control
group comprising 47 samples with normal transversal maxilla. The
average age of the control group at the first observation was 9.94
+ 2.11 years and RME group before treatment was 10.15 + 2.22 years.
In 71 patients, orthodontic treatment was started with RME,
followed by conventional orthodontic treatment, not combined with
any other form of orthodontic device. Twelve linear measurements,
including pharyngeal airway and soft palate dimensions were
determined. The lateral cephalometric radiographs were taken at the
first examination for pretreatment and annual follow up for
post-treatment was undertaken. All cephalometric radiographs were
hand-traced by one investigator using 0.35 mm lead 2H pencil on
0.003 mm matte acetate tracing paper in a darkened room with
extraneous light from the viewing box. All tracings were measured
with a digital caliper. The differences between the RME and the
control group were compared. The pharyngeal area and soft palate
changed following RME treatment in the RME group and with growth in
the control group. In the RME treatment group, there were
statistically significant differences between the facial type of
males and sex-related differences in orthognathic patients. No
statistically significant differences were found between subgroups
of the control patients and between the RME and control groups with
the Mann Whitney U-test (P < 0.05). The results suggest that
airway dimension and soft palate underwent noticeable changes after
treatment with RME whereas the control group changed after growth
factor event and changing environment. These changes are usually
produced and may be compensated in time by natural growth. Thus RME
has been shown to be capable of assisting nature in the natural
process of growth. Finally, all patients considered for RME should
be examined for nasal obstruction and if obstruction is found,
prior to commencing orthodontic treatment, they should be referred
to an otolaryngologist for examination and treatment of the
problem.