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202 rev port estomatol med dent cir maxilofac. 2017;58(4):199-204

Table 2. Prevalence of dental and ear nose and throat Discussion
findings by deciduous and mixed dentition
Although the literature has been showing interest on the
Variables Deciduous Mixed impact of oral breathing in growth and dentofacial develop-
n % n % ment for many years, many questions remain unanswered
regarding the real meaning of nasal obstruction as an etio-
Sagittal relationship (n=867) logical factor for malocclusion. Classic cephalometric stud-
Normal 58 16.3 50 9.8
Class I malocclusion 159 44.7 250 48.9 ies have associated upper airway obstruction with skeletal
Class II malocclusion 110 43.0 159 31.1 and dentofacial deviations from the norm, but there are few
Class III malocclusion 29 8.1 52 10.2 clinical evaluations on these patients’ occlusion. 19-22
Vertical relationship (n=864) Cross-sectional studies, even the ones with a large sample
Normal 172 47.5 283 56.4 as this here presented, have some limitations that need to be
Deep bite 59 16.3 69 13.7 addressed. In this study, although children were supposed to
Open bite 131 36.2 150 29.9
be submitted to evaluation by the whole professional team at
Transversal relationship (n=874) the first appointment, sometimes that was not possible. For
Normal 283 78.4 382 74.5 example, the diagnosis of allergic rhinitis was not made in the
Posterior crossbite w/o shift 40 11.1 88 17.1 first appointment in some cases due to antihistamine use or
Posterior crossbite w/ shift 38 10.5 43 8.4
airway infections, and patients did not show up on recall.
Tonsils status (n=874) Therefore, some data was missing from the original 1002 pa-
Grades 0, I, II 172 46.6 330 65.3 tients. All non-syndromic children, in both deciduous and
Grades III, IV 197 53.4 175 34.7
mixed dentition, who were consecutively referred and diag-
Adenoid obstruction status (n=832) nosed as mouth breathers enrolled the present study and,
<75% 111 32.0 257 53.0 therefore, the age range was wide. There was no information
≥75% 236 68.0 228 47.0
available on the onset of oral respiration, sucking habits, and,
Rhinitis (n=778) due to radiation issues, lateral x-rays were not available to
Yes 187 57.0 333 74.0 differentiate skeletal from dental malocclusions.
No 141 43.0 117 26.0
Some studies representing the general population, and not
Number of children (n) and prevalence given in percentage (n/N X100%) only the mouth breathers, can be found in the literature. In the
present sample with nasal obstruction, the prevalence of class
II malocclusion was 43.0% in the children in deciduous denti-
perplasia was more prevalent (53.4%) in the children in de- tion and 31.1% in the ones in mixed dentition. These numbers
ciduous dentition than in the ones in mixed dentition (34.7%). differ from other studies made in Brazil by Tomita et al. and
23
24
The opposite was verified for rhinitis, with more cases in Sadakyio et al., which showed a class II prevalence between
mixed (74.0%) than in deciduous dentition (57.0%). Posterior 6% and 20% in pre-school children. The higher prevalence of
crossbite with and without a functional shift, anterior open class II malocclusion in the mouth breathers in mixed denti-
bite and class II malocclusion were found in similar percent- tion comparing to those in deciduous dentition can be ex-
ages in children in deciduous and mixed dentitions. plained either by the longer influence of the mouth-breathing
The chi-square test (Table 3) showed no association between problem or simply by the transition to mixed dentition, which
type of obstruction (tonsils, adenoids and rhinitis) and the differ- could naturally result in class II canine in some cases. More
ent types of malocclusion – class II, open bite and crossbite (p>0.05). epidemiological studies on the sagittal relationship during the

Table 3. Bivariate analyses, using the chi -square test, between the obstructive causes for mouth breathing (independent
variables) and class II, anterior open bite and posterior crossbite (dependent variables)
Class II malocclusion Anterior open bite Posterior crossbite
Variables
(n=290) (n=282) (n=230)
Tonsil and/or adenoid obstruction
Yes (n=602) 197 (32.7%) 189 (31.4%) 153 (25.4%)
No 314 320 364
p=0.824 p=0.264 p=0.751

Only rhinitis
Yes (n=520) 70 (13.5%) 71 (13.6%) 65 (12.5%)
No 161 162 170
p=0.719 p=0.574 p=0.322
No obstruction cause diagnosed
Yes (n=69) 23 (33.3%) 22 (31.9%) 12 (17.4%)
No 42 44 43
p=0.800 p=0.604 p= 0.800
Number of children (n) and prevalence given in percentage (n/N X100%)