Page 14 - SPEMD_59-2

72 rev port estomatol med dent cir maxilofac. 2018;59(2):67-74

alignment showed a statistically significant difference (p<0.05) Discussion
between the groups, as the group with an oral breathing pat-
tern had greater, more positive values. In our sample of males and females aged 12 to 15 years, 63.3%
Class II occlusion predominated in individuals with mild of individuals presented a predominance of oral breathing,
TMDs (Table 4). Using a chi -square test to compare Class I and which is coherent with data from studies that reported varia-
Class II variables in the absence and presence of mild TMDs, tions between 6.6% and 77.8% of prevalence. Those varied re-
we found statistically significant differences (p<0.05) between sults could relate to the different methods used to assess
the groups (Table 4). breathing mode in those studies. 5,18,19,20
Regarding postural evaluation, our results indicate that
oral breathers tend to have a more forward head posture than
nasal breathers, which could stem from the former’s need to
Table 4. Comparative analysis of occlusal class according adapt their posture and thus the position of the head in order
to the TMDs severity
to promote the passage of air through the oropharyngeal
Occlusal Class Chi -square space. 1,6 -8 The literature supports our results by describing a
TMDs Severity Total test forward head posture as a major change in individuals with
Class I Class II Class III (p value)
a dominant oral breathing pattern. 7,9 Baldini et al. (2013) 6
TMDs -free 47 15 5 67 <0.001 found that the change in head posture could change the rest-
ing position of the jaw and occlusal contacts, as well as pro-
Mild TMDs 25 35 8 68
mote changes in the masticatory pattern, and that the breath-
Moderate TMDs 2 1 1 4 ing pattern would thus determine the development of
malocclusion. 5,19 Similarly, other authors 7,10 reported a rela-
Total 74 51 14 139
tionship between an oral breathing pattern and Angle Class
II occlusion, which our results corroborate. We also verified
statistically significant differences between the breathing pat-
The adjusted model was statistically significant (G2 (24) tern and Angle occlusal class. The dominance of the Class II
= 48.317; p<0.01), and statistically significant estimates of occlusal pattern in oral breathers could derive from a different
coefficients of the model are presented in Table 5. Accord- positioning of the tongue in the oral cavity that inhibits man-
ing to the adjusted model, only the breathing pattern sig- dibular growth and stimulates forward maxillary growth. In
nificantly influenced an increase in the lower cervicofacial accordance with the above three parameters, Nobili and Ad-
20
ratio, and the breathing pattern and age significantly in- versi (1996) related posture to Angle occlusal classification
fluenced the development of mild TMDs. Variables con- by demonstrating that individuals with Class II malocclusion
cerning head and neck posture, sex, occlusal class, and tilted their heads forward. Our results have also shown chang-
facial profile did not influence the results significantly es in the anterior view of the horizontal head alignment be-
(p>0.05). tween oral and nasal breathers. To our knowledge, there is no
Females presented a higher proportion of mild TMDs (60%), biological reason that could justify this directionality. The
although the relationship between gender and TMDs severity authors acknowledge that this may be a finding with no sci-
was not statistically significant (p=0.290). entific grounding.

Table 5. Summary of the multinomial regression analysis regarding statistically significant variables that predict lower
cervicofacial ratio and temporomandibular disorders (TMDs) severity

Dependent Predictable B Std. Error X2 Wald p value OR 95% CI
Variable Variable

Oral Breathing 2.266 0.692 10.714 0.001 9.643 [2.483; 37.457]
Increased Lower
Cervicofacial Ratio a Nasal Breathing 0 c – – – – –
Age 0.795 0.296 7.241 0.007 2.215 [1.214; 3.953]
Mild TMDs b Oral Breathing 1.390 0.530 6.875 0.009 4.014 [1.420; 11.343]
Nasal Breathing 0 c – – – – –
OR: Odds Ratio; CI: Confidence Interval
a The dependent variable is the lower cervicofacial ratio, which has three categories (normal, increased and decreased). The reference category in
this model is “normal”.
b The dependent variable is temporomandibular disorders’ severity, which has four categories (TMDs -free, Mild TMDs, Moderate TMDs and
Severe TMDs).
The reference category in this model is “TMDs -free”.
c This parameter is set to zero because it is redundant.