Original Article
http://doi.org/10.1590/2317-6431-2016-1723
ISSN 2317-6431
Bite force in children with posterior crossbite
Força de mordida em crianças com mordida cruzada posterior
Monize Vilela1, Melissa Nara de Carvalho Picinato-Pirola2, Lúcia Dantas Giglio3, Wilma Terezinha AnselmoLima3, Fabiana Cardoso Pereira Valera3, Luciana Vitaliano Voi Trawitzki3, Tais Helena Grechi1
ABSTRACT
RESUMO
Introduction: The bite force is influenced by the occlusal condition. In
children with posterior crossbite the results are controversial. Purpose:
To investigate the influence of posterior crossbite in maximal isometric
bite force (MIBF) in children with mixed dentition. Methods: In this
cross-sectional study, 32 children participated, 21 of them belonging to
the posterior cross-bite group (10 girls and 11 boys, mean age 9.2 years)
and 11 to the control group (6 girls, 5 boys, mean age 9.3 years). The
children were evaluated by an orthodontist for occlusal diagnosis and
characterization of the groups, by otorhinolaryngologists for evaluation
of respiratory symptoms and by a speech therapist to identify the clinical
and MIBF myofunctional orofacial condition. The dynamometer was
placed in the molar region and the children were instructed to bite it as
hard as possible three times alternately. For data analysis, Student’s t-test
for independent samples was used. The level of significance was set at
5%. Results: While comparing the groups crossbite vs. control, there
was no significantly difference; also, among only children belonging to
the crossbite group, there was no difference between the sides (crossed
bite vs. Noncrossed one). Conclusion: The presence of posterior
crossbite did not influence the maximal isometric bite force in children
with mixed dentition.
Introdução: A força de mordida é influenciada pela condição oclusal.
Em crianças com mordida cruzada posterior, os resultados são
controversos. Objetivo: Investigar a influência da mordida cruzada
posterior na força isométrica máxima de mordida, em crianças na fase
de dentição mista. Métodos: Participaram deste estudo transversal 32
crianças, sendo 21 do grupo mordida cruzada posterior (10 meninas
e 11 meninos, média de idade 9,2 anos) e 11 do grupo controle, sem
alterações oclusais (seis meninas, cinco meninos, média de idade 9,3
anos). As crianças foram avaliadas por um ortodontista, para diagnóstico
oclusal e caracterização dos grupos, pela equipe de otorrinolaringologia,
para avaliação do quadro respiratório, e por uma fonoaudióloga. O
dinamômetro foi posicionado na região dos molares e as crianças
foram instruídas a mordê-lo o mais forte possível, por três vezes,
alternadamente. Para análise dos dados foi utilizado o teste t de Student
para amostras independentes e dependentes. O nível de significância
estabelecido foi de 5%. Resultados: Na comparação entre os grupos
mordida cruzada e controle não foi encontrada diferença significativa e
no grupo mordida cruzada, não houve diferença entre o lado cruzado e o
não cruzado. Conclusão: A presença de mordida cruzada posterior não
esteve relacionada à força de mordida em crianças na fase de dentição
mista.
Keywords: Bite force; Malocclusion; Child; Dentition, Mixed
Palavras-chave: Força de mordida; Má oclusão; Criança; Dentição
mista
Research conducted at Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, School of Medicine of Ribeirão Preto – Universidade
de São Paulo – USP – Ribeirão Preto (SP), Brazil.
(1) Clinical Hospital, School of Medicine of Ribeirão Preto – Universidade de São Paulo – USP – Ribeirão Preto (SP), Brazil.
(2) School of Ceilândia, Universidade de Brasília – UnB - Brasília (DF), Brazil.
(3) School of Medicine of Ribeirão Preto – Universidade de São Paulo – USP – Ribeirão Preto (SP), Brazil.
Conflict of interests: No
Authors’ contribution: MV main author, it’s responible for data organization, tabulation of results, analysis and writing; MNCPP writing and critically revising
the manuscript; LDG writing and critically revising the manuscript; WTAL contribution to assess respiratory condition and critically revising the manuscript; FCPV
contribution to assess respiratory condition and critically revising the manuscript; LVVT contribution to analysis of the results and writing; THG data collection,
writing and critically revising the manuscript.
Corresponding author: Monize Vilela. E-mail: monize.vilela@hotmail.com
Received: 6/9/2016; Accepted: 11/23/2016
Audiol Commun Res. 2017;22:e1723
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Vilela M, Picinato-Pirola MNC, Giglio LD, Anselmo-Lima WT, Valera FCP, Trawitzki LVV, Grechi TH
INTRODUCTION
METHODS
Posterior crossbite is a malocclusion in the canine, premolar
and molar regions, where the buccal cusps of the upper teeth
lingually occlude the vestibular cusps of the corresponding
lower teeth(1). It can occur unilaterally or bilaterally and be
present in the different stages of the dentition.
Some studies have related posterior crossbite with the
presence of deleterious oral habits, orofacial myofunctional
disorders and oral breathing(2,3). Posterior crossbite, considered one of the most frequent types of malocclusion in the
deciduous and mixed dentition phase, presents a prevalence
of 7.2% to 23%(4). It can produce changes in mandibular symmetry(5), in the electromyographic activity of the muscles of
mastication(6), in the coordination and masticatory pattern(7),
in the swallowing(3) and in the bite force(8,9). The bite force
is understood as the exertion between the upper and lower
teeth when the jaw is raised by the muscles of mastication(10).
It is an important tool to evaluate the functional status of
the masticatory system(11) and was used to evaluate the oral
function in different malocclusions, in the oral surgeries,
temporomandibular disorders and in the neuromuscular
diseases(12).
The bite force was previously investigated in children
with posterior crossbite, in the deciduous and mixed dentition
phase. The main objective of the studies was to evaluate the
effect of orthodontic treatment on the correction of malocclusion(8,13,14,15). The results of these studies differ from each
other, but generally point to similar forces in the orthodontic
pre-treatment phase, as well as after the restraint, and to
different forces in the phase immediately after orthodontic
treatment.
It is worth remembering that the bite force can be influenced
according to the craniofacial morphology(16), sex(17), age(18), presence of signs and symptoms of temporomandibular disorder(19)
and number of teeth(16).
Although some studies have focused on the myofunctional
orofacial condition and bite force in children with posterior
crossbite, in different age groups, the results are still controversial, which makes it difficult to understand the occlusal
relationship and myofunctional orofacial condition.
The purpose of this study was to investigate the influence
of the posterior crossbite on the maximal isometric bite force
(MIBF) in children in the mixed dentition phase.
Sample
The present project was approved by the Research Ethics
Committee of Clinical Hospital of School of Medicine of
Ribeirão Preto, Universidade de São Paulo (HC/FMRP- USP),
under no. 6443/2007. Thirty-two children in the mixed dentition
phase, aged between 7 and 10 years, participated in this crosssectional study. The children were divided into two groups:
crossbite group, 21 children with posterior crossbite, of whom
14 had unilateral posterior crossbite, 3 with unilateral posterior
crossbite associated with anterior open bite, and 4 with bilateral
crossbite; control group, with 11 children without occlusal
alterations. The children were selected by an orthodontist at
Preventive and Interceptive Orthodontics Clinic of School of
Dentistry of Ribeirão Preto - USP and at Center of The Mouth
Respirator (CERB) of the Otorhinolaryngology Division of
HC/FMRP-USP.
Descriptive data regarding the sex and age of the studied
groups are shown in Table 1.
In the crossbite group, children in the mixed dentition
phase, with unilateral or bilateral crossbite, involving canines
and deciduous molars and first permanent molars, with indication of orthodontic treatment, without restriction regarding
the respiratory condition and other associated malocclusions
were included.
In the control group, children in the mixed dentition phase,
without occlusal alterations, who had never used orthodontic
and/or orthopedic appliances, with age close to the crossbite
group and without restrictions regarding the respiratory condition were included.
Children with genetic syndrome, congenital and acquired
dentofacial deformities, the ones with extensive tooth cavities,
history of neurological treatment, history of gastroesophageal
reflux, history of orthodontic and/or functional orthopedic
treatment and previous orofacial myofunctional speech therapy
were excluded.
Dental (oral) evaluation
For occlusal diagnosis of the children, clinical evaluation
was performed and it was asked complete orthodontic documentation (lateral and occlusal cephalometric x-rays, study
Table 1. Sex and age of the researched groups
Groups
n
Crossbite
Control
Sex
Age (mean)
Standard
deviation
p-value
0.74
F
M
21
10
11
9.2
1.04
11
6
5
9.3
0.92
Student’s t-test (p<0.05)
Subtitle: F = female; M = male
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Audiol Commun Res. 2017;22:e1723
Bite force in children
models, intraoral photographs and extraoral photographs, from
front and profile). For the posterior crossbite group, children
who presented the region of canines, premolars and molars in an
abnormal position, in the vestibulolingual direction (vestibular
cusps of the upper teeth lingually occluding the vestibular cusps
of the corresponding lower teeth) were selected. The children of
the control group should present Class I (Angle Classification)
of the deciduous canines (mesial surface of the superior canine
cusp occluding the distal surface of the lower canine) and vertical and horizontal trespass (overbite and overjet, respectively)
of the normal incisors(1).
Otorhinolaryngological evaluation
Figure 1. Digital dynamometer with capacity up to 100 kilograms-force
(Kgf)
The evaluation of the upper airways was performed at
the otorhinolaryngology department of a school hospital,
including anterior rhinoscopy and nasofibroscopy (Pentax®
FNL – 10RP2, 3.4 mm flexible fibroscope for children) for
measurement of adenoid size.
Of the 21 children in the crossbite group: 10 (47.62%) had
from 10 to 50% of cavum obstruction; 6 (28.58%) from 50 to
70% of obstruction; and 5 (23.80%) from 70 to 100% of obstruction. Of the 11 children in the control group: 7 (63.64%)
presented from 10 to 50% of cavum obstruction; 2 (18.18%)
from 50 to 70% of obstruction; and 2 (18.18%) from 70 to
100% of obstruction.
Bite force evaluation
The bite force measurements were performed using a
digital dynamometer, IDDK model (Kratos®, Cotia, São
Paulo, Brazil), with capacity up to 100 kilograms-force (Kgf),
adapted to oral conditions. The apparatus has a scale in Kgf
and Newton (N), set zero key, which allows exact control of
the obtained values and also a peak register that, during the
obtainment of the values, facilitates the reading of the maximum force (Figure 1).
During the examination, the children remained seated in
a comfortable chair with their feet flat on the floor and their
head parallel to the horizontal plane. To measure the bite force,
the device was positioned in the region of the molar teeth, on
both sides of the dental arcade, alternately, and the children
were instructed to bite it as hard as possible. Three records
were made for each side, with a non-standard rest between
the records. The maximum bite force was recorded in Kgf by
recording the force peak indicated on the screen and the values
were noted in the protocol of each child for further analysis.
Data analysis
For the analysis of the bite force, the average of the three
measurements obtained on each side was considered. The
statistical package SPSS (version 17.0) was used and the
value of p<0.05 was adopted as a level of significance. The
Kolmogorov-Smirnov test was applied to check the normality
of data distribution.
The Student’s t parametric test was then performed, being
unpaired when the crossbite group and the control group were
compared, and paired when the crossed and noncrossed sides
were compared in children with unilateral crossbite.
RESULTS
There was no significant difference (p<0.05) between the
posterior crossbite and the control groups for MIBF, on both
sides (Table 2).
There was no significant difference (p>0.05) between the
crossed and noncrossed sides for MIBF in the posterior crossbite group (Table 3).
DISCUSSION
The bite force makes it possible to verify the functional
state of the masticatory system. Thus, it results from the action
Table 2. Mean, standard deviation and comparison between the crossbite and control groups in relation to the maximal isometric bite force
Right side
Left side
Group
n
Mean
SD
P
Mean
SD
P
Crossbite
21
23.81
10.32
0.94
23.94
9.61
0.67
Controle
11
24.08
7.40
22.35
9.43
Subtitle: SD = standard deviation; P = probability in Student’s t-test for independent samples. Values in Kgf.
Audiol Commun Res. 2017;22:e1723
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Vilela M, Picinato-Pirola MNC, Giglio LD, Anselmo-Lima WT, Valera FCP, Trawitzki LVV, Grechi TH
Table 3. Mean, standard deviation and intragroup comparison between
crossed and noncrossed sides in relation to maximal isometric bite force
Crossed side
Noncrossed side
Mean
SD
P
26
9.3
0.6
26.7
8.5
Subtitle: SD = standard deviation; P = probability in the Student t test for dependent samples. Values in Kgf.
of the mandibular elevator muscles and can be modified by
craniofacial biomechanics(20).
In this study, a sample of children with posterior crossbite
was selected, in order to verify its influence on the bite force.
The hypothesis was that the altered morphological condition
of the children with this malocclusion could influence on the
bite force.
Authors reported that children with unilateral posterior
crossbite have a tendency to irregular and contralateral masticatory cycles to the crossed side(21,22,23). Other studies(7,24,25) highlighted the presence of asymmetry of the electromyographic
activity of the muscles of mastication between the crossed and
noncrossed sides.
In the present study, no significant difference was found
in the comparison between the groups (crossbite and control)
and in the intragroup analysis (crossed and noncrossed sides)
in children in the mixed dentition phase. One study(8) verified
the bite force in children with posterior crossbite, with no restrictions on respiratory conditions and at a similar age to that of
the children in this study. The results also showed no significant
difference between children with and without malocclusion.
The bite force in children with malocclusion was studied
by some authors(15) who compared them with children without
malocclusion, but in the deciduous dentition phase, differing
from this research regarding the teething phase. However, the
authors verified that the type of occlusion did not affect the
bite force values, confirming the findings of the present study.
Another study(14) analyzed the bite force at different stages
of orthodontic treatment and found similar forces between
the right and left sides in children with unilateral crossbite.
The level of the bite force was lower immediately after the
orthodontic treatment, and higher after the restraint, with
approximate values of children without malocclusion. These
results are in agreement with the findings of the present study,
although the objective was not to analyze the bite force after
the orthodontic treatment.
Some studies(8,13) compared children in the mixed dentition phase, with and without posterior crossbite and found a
significant difference, with higher strength values in children
without malocclusion. This divergence from the results of this
study can be attributed to the number of participants, since the
number was lower in this sample.
Another factor that may influence bite force results is the
positioning of the assessment tool. Authors(26) have pointed out
that may occur variations in bite forces, associated with the
4 | 5
instrumentation and the position of the transducer in relation
to the dental arch. A transducer positioned more posteriorly
produces a greater bite force, which may be attributed probably
to the mechanical lever system of the jaws.
It is also worth noting that the bite force can be influenced by
the eruption stage of the teeth, the number of teeth in occlusal
contact, the presence of malocclusion and the degree of axial
inclination of the teeth in crossbite(8).
The differences between the studied age range(15) and the
sample size(8,13) made it difficult the direct comparison of the
studies found with the results of this research, in which children
with different respiratory conditions were included in both
groups and the presence of nasal obstruction may have influenced the bite force values. The relationship of the respiratory
condition and the bite force in children is little investigated in
the literature. It is known that oral breathing can influence the
growth pattern and the craniofacial morphology, variables that
are important in determining the bite force(27).
New studies, with a greater number of participants, are
needed to better elucidate the effects of posterior crossbite
on the orofacial musculature, thus contributing to the basis of
orofacial myofunctional work.
CONCLUSION
The presence of posterior crossbite did not influence the
bite force in children in the mixed dentition phase.
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