Influence of posture on swallowing - European Journal of Paediatric

A. Lumbau, L. Schinocca, G. Chessa
proprioceptive sensory system located in the periodontal
ligament, muscles, bones and joints. Therefore occlusion
and posture of the tongue have a key role in the genesis
of acquired postural reflexes [Guidetti et al., 1993; Molina,
1998; Esposito, Meersseman, 1988; Tolu et al., 1993; Lai
et al., 2003]. Posturology has underlined a strict
correlation between occlusal class and posture on the
sagittal plane, due to the influence exerted by the
mandibular position on the static posture through the
muscle chains and the cranio-cervical-mandibular
connections [Bricot, 1999]. In fact, subjects with Class I
occlusion show alignment between the scapular and
gluteal plane, Class II subjects exhibit an anteriorised
scapular plane, and in Class III subjects the scapular plane
is posteriorised [Bricot B., 1999].
University of Sassari, Dental Institute, Sassary, Italy
e-mail: [email protected]
Influence of posture
on swallowing
ABSTRACT
Aim This study investigates the relationship between posture
disorders and swallowing, either of infantile type or affected
by the presence of a short lingual frenulum.
Materials and methods The stabilometry examinations,
taking into account the Romberg index and the LFS value, and
when needed a frenectomy, showed positive variations in the
recovery of a proper posture. The data were analysed by
means of the Wilcoxon signed-rank test.
Results and conclusion This study showed that swallowing is
able to modulate postural control and it can be a determining
factor in postural syndromes that, if not promptly intercepted,
may evolve into full-blown and irreversible musculoskeletal
disorders for which treatment often proves ineffective.
Keywords: Posture; Swallowing; Stabilometric platform.
Introduction
Maintenance of the upright position is ensured by a
complex network of nerve pathways and centers that
collectively are called postural system [Lai et al., 2003].
Posture is determined by the tonic contraction of the
extensor muscles that oppose gravity, thus enabling joints to
support the body weight. The tonic postural system matures
around 10-12 years of age and it consists of
interrelationships and interdependencies between the
following functional systems [Bricot, 1999]: podalic,
stomatognathic, auditory and vestibular, visual-ocular,
cutaneous, psychoemotional, craniosacral, joints and
muscles (proprioceptive system). Specific receptors located in
different subsystems (feet, eyes, mouth, labyrinth, skin,
muscles, etc.), through specific sensorimotor circuits send
continuous inputs to the central nervous system where they
undergo processing and integration processes (cognitive
processes), which determine the control and postural
regulation [Esposito, Meersseman, 1988].
The stomatognathic system represents the trait d'union
between the anterior (masticatory, hyoid and tongue
muscles) and posterior muscle chains (cervical and neck
muscles) [Piret and Beziers, 1986; Capozzi, Negri, 1993].
Stomatognathic system
The
stomatognathic
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Tongue and posture
During development, the size of the tongue in relation
to the oral cavity is disproportionate, allowing the former
to play a key role in shaping the palatine vault, with
enlargement of the maxillary and mandibular alveolar
processes, and in determining the curves of Spee and
Wilson and the interocclusal rest space [Zavarella, 2002;
Balercia, Balercia., 1985; Fellus, 2006]. Tongue has a key
role in swallowing. The hyoid bone represents a
coordination centre that informs the brain and related
structures and modulates the kinematic patterns of jaw
and neck. Hyoid bone and tongue represent the link
between oral and spine functions, and the hyoid bone is
the main component in the cranio-cervical-mandibular
relationship [Rocabado, 1983]. Its dynamic affects
swallowing, and in turn it is influenced—due to its
neuromuscular connections—by the dynamics of tongue,
occlusion, and the position of the head or more generally
speaking by body posture. Swallowing of the food bolus
occurs about 150 times in the 24 hours, but for the
purpose of postural muscle control involuntary swallowing
of saliva is more important, and it occurs every 30 seconds
during waking and about one time per minute during
sleep: that is, about 2000 times in the 24 hours. Under
normal conditions, the buccinator and mimic muscles
exert a lateral centripetal force during swallowing; the tip
of the tongue pushes against the interincisal palatal
papilla, the middle portion of the tongue pushes against
the hard palate, while the back of the tongue is tilted 45°
against the pharyngeal wall [Shilder, 1990].
In the case of swallowing disorders the tip of the tongue
pushes against the upper or lower teeth or the
interocclusal space, the middle portion is lowered or
extended unilaterally and the posterior third of the tongue
rises against the back of the hard palate. The above can
create a vicious cycle that, in trying to find a
neuromuscular compensation to stabilise the jaw during
swallowing, will have local and remote effects. Therefore
the involved muscles will be forced to contraction in a
different, unbalanced way able to negatively affect the
whole muscle postural chain. The suprahyoid muscle
tension increases and the hyoid bone will move to a higher
position [Rocabado, 1983] (Fig. 1). It should be
emphasised that, since the descending correlation
between occlusion, posture and swallowing can be
proved, an ascending correlation between posture of the
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LUMBAU A., SCHINOCCA L. AND CHESSA G.
FIG. 1 - Muscle postural chain.
trunk and limbs and masticatory system is also possible
(based on the notion of muscle chains) [Bricot, 1999;
Guidetti, 1997]. The scientific literature is not always in
agreement with an anatomical and functional correlation
between tongue dynamics, swallowing, and body posture.
The purpose of this paper is to study whether treatment
of different forms of abnormal swallowing was able to
change the body posture in a group of 10 patients of
paediatric age.
Materials and methods
For this study, 6 females and 4 males aged between 10
and 12 years with swallowing and tongue posture
disorders were selected at the Department of Prosthetic
Dentistry of the University of Sassari, Italy. Of the
examined patients 5 had ankyloglossia, and the remaining
5 exhibited disorders of the tongue dynamics due to
anterior open bite. For the clinical evaluation of the
patients it was employed the gnathology chart based on
the European Academy of Craniomandibular Disorders
(EACD), as modified by the school of Turin. In addition to
the traditional clinical evaluation of posture, computerised
stabilometry was also used. Before treatment, each patient
Patient
RHS
Patient 1 (M)*
Patient 2 (F)*
Patient 3 (M)
Patient 4 (F)
Patient 5 (F)
Patient 6 (M)
Patient 7 (M)
Patient 8 (M)
Patient 9 (F)
Patient 10 (F)
2.067
1.826
3.574
0.569
0.352
0.738
1.708
0.380
3.871
0.411
Results
Romberg Index before and after correction is reported in
tables 1 and 2. Data were analysed with the Wilcoxon
signed-rank test. The value obtained for the LFS (surface
lenght) test before and after treatment is 5 (range 3-8),
with a critical value for · of 0.05.
Discussion
The stabilometric analysis shows that the majority of
patients achieved an improvement in their posture after
correction of the tongue dynamics, as underscored by the
RHS after treatment
0.677
0.727
3.097
0.402
1.289
0.990
0.504
0.380
0.324
0.745
F*: Patient with ankyloglossia M*: Patient with anterior open bite
TABLE 1 - Romberg Habitual Swallowing Index before and
after correction.
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underwent a complete stabilometric examination, which
was then repeated after completion of treatment. The
stabilometric test was performed with the stabilometric
platform BioPosturalSystem 3.2. according to the protocol
of the Association Française de Posturologie (AFP). The
indices considered for the study were the following: the
Romberg index or the ratio between the surface of the
statokinesigram with the eyes closed and the surface of
the statokinesigram with the eyes open (this index
provides useful information on the influence of the visual
and oculomotor systems on posture. Mean values with
closed eyes: 249; lower and upper limit: 112 and 677,
respectively); and the LSF which represents the length of
the statokinesigram as a function of posture and provides
useful information on the precision of postural control and
above all on the effort made by the subject to control
posture. Where needed a frenectomy was also performed.
The sensitisation tests included in our programme were
the following: open eyes/closed eyes for the evaluation of
the oculomotor and visual systems; closed mouthhabitual swallowing (open eyes/closed eyes) for the
evaluation of occlusion and of the entire stomatognathic
system; closed mouth-correct swallowing (open
eyes/closed eyes) to assess the influence of swallowing on
posture. Correction of swallowing dynamics was
performed by means of frenectomy in those patients with
ankyloglossia, and by means of dental wax in those
patients with open bite.
Patient
Patient 1 (M)*
Patient 2 (F)*
Patient 3 (M)
Patient 4 (F)
Patient 5 (F)
Patient 6 (M)
Patient 7 (M)
Patient 8 (M)
Patient 9 (F)
Patient 10 (F)
LFS habitual Swallow. LFS swallow. after treat.
8.47
4.33
43.17
28.54
16.14
5.81
5.39
8.28
14.07
8.36
10.85
5.79
1.8
1.1
4.93
0.8
46.64
4.14
13.92
14.63
F*: Patient with ankyloglossia M*: Patient with anterior open bite
TABLE 2 - LFS before and after correction of swallowing.
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POSTURE AND SWALLOWING
the LFS index. This result demonstrates that obtaining a
correct functional relationship between tongue, lowering
and elevator muscles of the jaw, occlusal contacts and
hyoid bone lead to a proper head position, which
ultimately affects the position of the body. As a result,
after treatment 8 over 10 patients obtained an
improvement of the postural parameter considered in the
study. In fact, the elevator muscles of the jaw, acting as
antigravity muscles, maintain the mandibular posture by
means of the myotactic reflex, which works by activation
of proprioceptive receptors of the same elevator muscles,
temporomandibular joint and periodontal receptors
[Ramfjord, 1969]. However, clinical observations showed
changes in mandibular posture in subjects with intact
trigeminal system [Deriu, 2000]. These data suggest that
control of mandible posture originates also from other
nervous structures, which together with the trigeminal
structures contribute to the perfect adjustment of the
mandible position in relation to the position of the head
and that of the various body segments [Chessa et al.,
1999; Deriu, 2000; Haberfellner, 2005]. Therefore it can
be easily inferred that the systems involved in the control
of posture, and in particular the vestibular labyrinth, affect
the elevator muscles of the jaw [Barbato et al., 1996]. Is
has also been observed that patients with vestibular
symptoms may develop disorders of the masticatory
muscles [Guidetti, 1997]. These data support the
hypothesis that temporomandibular joint, spine, scapular
cingulum and joints in proximal-distal sequence are
interdependent [Deriu, 2000]; the postural problems of a
region do not remain circumscribed to that specific region
but affect the neighboring segments according to a
postural chain of vertical type [Gelb, 1977; Rocabado,
1983].
This leads to activation of compensatory mechanisms
aimed to recover and maintain body balance, but the
fatigue of the muscle groups involved in the compensation
will eventually affect the region with postural problems
even further [Guidetti, 1997; Da Cunha, et al., 1991;
Redstone,2004; Bazzotti, 1998]. The lack of postural
improvement after frenectomy of patient N. 4 can be
interpreted taking into account the occlusion, since the
subject had a deep bite with anterior dental wall, which
according
to
the
interrelationships
FIG. 2 - Stabilometric test before and after correction of
swallowing.
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occlusion/muscles/hyoid bone/tongue position is able to
affect the position of the body. From the analysis of the
Romberg index, which as previously stated represents the
visual interference on postural control, it can be seen that
in 4 patients an improvement of the LSF corresponds to
worsening of the index itself, which shifts towards
pathological ranges. Supported by the data found in the
literature [Bricot, 1999; Guidetti, 1997; Piret, Beziers,
1971; Da Cunh et al., 1991] we hypothesised that a
postural improvement can reveal visual disorders which
had been previously masked by the posture [Bricot, 1999].
In the other patients improvement of the LFS parameters
and Romberg index overlaps. In these patients the visual
disorders were of adaptive type, in fact—as evidenced by
Guidetti [1996] in his treatise—the nerve fibers of the
oculomotor muscles use the ophthalmic branch of the
trigeminal nerve to reach their respective nuclei. Therefore
a trigeminal hyperexcitability due to swallowing disorders
can modulate the nervous control on the oculomotor
muscles.
Conclusion
This study, despite the small number of patients but
supported by the statistic evidence, shows that swallowing
can modulate postural control and that therefore—
together with the regulation of other receptors—it can be
a determining factor in the treatment of those postural
syndromes that, if not promptly, may evolve into fullblown and irreversible musculoskeletal disorders for which
treatment often proves ineffective. Acknowledgments
We thank for their cooperation Mrs. Antonina Mura,
dental hygienist, and Giovanna Senes, registered nurse.
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