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rev port estomatol med dent cir maxilofac . 2018;59(2):67-74 73

In our study, most children presenting Class I malocclusion of our study, and further trials should be performed to enlight-
had no TMDs according to the Fonseca Anamnestic Index. en the scientific community regarding their feasibility.
However, 70% of Class II individuals had mild TMDs, with a One limitation of this study is the absence of a clinical ex-
statistically significant relationship between the groups. Some amination and laboratory findings for the diagnosis of TMDs.
21
authors found that some occlusal factors, particularly Class- Instead, we used a valid and reliable questionnaire – Fonseca’s
es II and III, are risk factors for the development of TMDs. Most Anamnestic Index, which is a self -reported questionnaire often
children in our study who were oral breathers and had Class used for epidemiological studies on TMDs that allows charac-
II occlusion exhibited that feature. terizing the signs and symptoms of TMDs and obtaining a score
27
Our study also found that individuals with oral breathing about TMDs severity. Moreover, different studies support the
had an increased risk of developing mild TMDs, as corroborat- use and validity of questionnaires for epidemiological studies
22
ed by the results of Chaves. That situation could result from on TMDs’ symptoms. 28,29 Since this was a cross -sectional study,
an altered function, which may constitute repetitive trauma no etiological conclusions can be drawn, and the reader should
to the TMJs and consequent dysfunction. have in mind that no clinical confirmation of the data retrieved
Our results show a statistically significant relationship be- by the participants was available.
tween the oral breathing pattern and Class II malocclusion.
23
Also, as literature has revealed, imbalances in facial muscles
in Class II individuals are normal, as a result of an increased Conclusions
overjet, and their facial profiles are generally convex. Some
authors 24 found a more convex profile among oral breathers Our results show an association between the presence of oral
than nasal ones, which our results confirm. breathing and head anteriorization, signs and symptoms of
Tourné (1990) 25 hypothesized that oral breathing was a TMDs, Class II malocclusion, convex facial profile, and in-
chief etiological factor of induced excessive vertical growth. creased lower cervicofacial ratio. TMDs were associated with
Our results seem to corroborate that hypothesis, since oral occlusal Class II, and oral breathers had an increased risk of
breathing increased the odds of having an increased lower developing mild TMDs and increased lower cervicofacial ratio.
cervicofacial ratio by nine -fold, and similar findings appear in Lastly, our results indicate no sex -related differences in the
other studies. 26 The functional matrix hypothesis could ex- prevalence of TMDs.
plain that influence of oral breathing on the lower cervicofacial
ratio. That hypothesis states that the origin, growth, and main-
tenance of all skeletal tissues and organs are always second- Ethical disclosures
ary, compensatory, and mandatory responses to temporally
and operationally prior events or processes that occur in spe- Protection of human and animal subjects. The authors declare
cifically related non -skeletal tissues, organs, or functioning that the procedures followed were in accordance with the reg-
spaces. That is, the function directly influences the shape. ulations of the relevant clinical research ethics committee and
Considering that nasal breathing represents an important with those of the Code of Ethics of the World Medical Associa-
function in the stomatognathic system, if that function is al- tion (Declaration of Helsinki).

tered to oral breathing, it may condition the skeletal growth of Confidentiality of data. The authors declare that they have
the surrounding structures. Oral breathing is thought to con-
tribute to a posterior rotation of the mandible, with a conse- followed the protocols of their work center on the publication
of patient data.
quent increase of the lower cervicofacial ratio, which could
also interfere with the TMJs and thus result in or contribute to Right to privacy and informed consent. The authors declare
the development of TMDs. Furthermore, it should be consid- that no patient data appear in this article.
ered that, in the growth period, the oral function may lead to
adaptative changes of the TMJ, since it is highly adaptative in
this period, responding to a wide variety of stimuli. According- Conflict of interest
ly, TMDs symptoms experienced by young people may be tran-
sitory, and this fact was not controlled in this study, as it is The authors have no conflicts of interest to declare.
beyond our scope.
Our results verified that changes in head and neck posture,
breathing pattern, dental occlusion and the presence or absence references
of TMDs presented an interdependent and complex relation-
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to reinforce the importance of developing an interdisciplinary Neuromuscular dentistry: Occlusal diseases and posture. J
assessment of the breathing pattern, postural changes, facial Oral Biol Craniofac Res. 2013;3:146 -150.
features, and presence of TMDs. Therefore, the authors hypoth- 2. Korbmacher H, Koch L, Eggers -Stroeder G, Kahl -Nieke B.
esize that the assessment of the individual as a whole could Associations between orthopaedic disturbances and
play an important role in intervention planning and the preven- unilateral crossbite in children with asymmetry of the upper
cervical spine. Eur J Orthod. 2007;1:100-4.
tive decision -making process. If changes are detected early, 3. Solow B, Siersbaek -Nielsen S. Growth changes in head
practitioners can increase the possibility of prevention and posture related to craniofacial development. Am J Orthod.
treatment. However, those considerations are beyond the scope 1986;89:132-40.