The «alphs»... or what is the efficient face of bite planes?
par Alfredo
MARINO+, Pierre-Marie GAGEY++
+Associazione Italiana di Posturologia Clinica
++Institut de Posturologie, Paris
Abstract
A
very discreet mechanical stimulation of the labial mucosa, realised by a small
extra thickness pasted on the vestibular face of incisive teeth, brings about
an important, immediate and non specific modification
of the control of orthostatic posture. The conclusion of this experience,
though it is coherent with the non linear dynamic
nature of the fine postural control system, deserves being confirmed by other
works because it queries too many explanatory models of the therapeutic
efficiency of occlusal gutters.
Introduction
Since
the first publication from Costen (1936) on relationships between posture and
mandible, practically no basic works - except perhaps those from Batini et
al. (1974) and from Meyer (1977) - were published to light the road of
therapeutists. Progressively however, in dental surgery offices, a practice
compelled recognition thanks to its efficiency: the wearing of a bite plane
(see Hartmann & Cucchi, 1993 for a review), and in fact Bonnier (1996)
showed that these prostheses in mouth can modify the functioning of the control
of orthostatic posture.
Whatever
be models, mechanical and/or neurophysiological, that guided the idea of the
different types of bite plane, they all end at the manufacture of a prosthesis
that put something like a hood on whole or part of an arcade. These gutters
therefore have three faces that contact adjoining anatomical structures: a face
between cusps, a vestibular face and a lingual face. Traditionally therapeutic
efficiency of gutters was attributed solely to its presence between cusps that,
by modifying occlusion, would act, mechanically and/or neurophysiologically, on
the positioning of ATM and on tonic balance of masticator muscles. Till now, as
far as we know, nobody put forward the hypothesis that stimulations of the
jugal and/or lingual mucosa, due to the presence of the gutter, could be, at
least partly, responsible for the efficiency of these prostheses.
This
hypothesis has been suggested to us by works of podologists that underline the
outstanding postural efficiency of very discreet plantar stimulations
(Villeneuve-Parpay et al.., 1995). As this hypothesis is in accordance
with the «butterfly effect» of the fine postural control system, a non-linear
dynamic system (Gagey et al.., 1998), we have decided to test it.
Material and Methods
The
protocol of this first experimental approach is voluntarily very simple: a
population of patients frequenting a dental consultation has been recorded on a
stabilometric platform before and after the fitting of a prosthesis on the
vestibular face of some teeth.
Alphs
After
mordanting with acid, for 10 seconds, of the vestibular faces of the four
superior incisive teeth (11, 12, 21, 22), rinsing with water and drying with
air, a very fine thickness of TRANSBOND 3M®, a composite photopolymerisable
material, was applied. The polymerisation was obtained by a 10 seconds exposure
to the light from a halogen lamp, emitting in the frequency band 400/500 nm.
Fit at the centre of the crown of each incisive tooth, roughly round, these
pasted prostheses had approximately a two millimetres diameter and a one
millimetre thickness; we call them «Alphs».
Population
Fifty seven patients who came to an orthognathodontic
consultation have been selected only on the criterion of their acceptance to
participate in this experience after they had been duly informed of conditions
of the protocol. Patients of this population did or didn´t show symptoms that
are usual in this kind of consultation: crackles and/or pains of the TMJ,
headache, cervical pain, rachialgias and sometimes dizziness. (Mean age: 24
years 6; 41 women, 16 men)
Recordings
Patients
were recorded on a stabilometric platform DYNATRONIC DYN 50®, built according
to the standards of the Association Française de Posturologie (Bizzo et al.,
1985), in the open eyes and closed eyes situations, and standard conditions of
the Association Française de Posturologie (A.F.P., 1985), few minutes before
and after the fitting of the alphs.
Signal analysis
For
signal analysis, the parameters retained by the Association Française de
Posturologie, whose statistical values in a normal population of reference are
published (A.F.P., 1985), were calculated; that is to say: the
X and Y-mean positions of the centre of pressure, the area of the confidence
ellipse that contains 90% of the sampled positions of the centre of pressure
(Takagi et al., 1985) and the parameters LFA and VFY described in
Normes85 (A.F.P., 1985).
Statistical analysis
A
comparison to zero of the mean of matched differences of these parameters
before and after the fitting of the alphs, was made by the Student´s t-test.
Results
The
distribution of each of studied parameters, before and after the fitting of the
alphs, is presented in the form of an histogram, the
Gaussian curve of the theoretical normal distribution of the parameter is drawn
as reminder. Class interval for all histograms is always equal to half standard
deviation of the theoretical normal distribution. The Student´s t shown on drawings
corresponds to the comparison to zero of the mean of matched differences
between the two histograms.
FIG. 1- Distribution of the X-mean parameter before and some minutes after the
fitting of the alphs. Eyes open situation. N= 57, ns.
FIG. 2- Distribution of the X-mean parameter before and some minutes after the
fitting of the alphs. Eyes closed situation. N= 57, ns.
FIG. 3- Distribution of the Y-mean parameter before and some minutes after the
fitting of the alphs. Eyes open situation. N= 57, ns.
FIG. 4- Distribution of the Y-mean parameter before and some minutes after the
fitting of the alphs. Eyes closed situation. N= 57, ns.
FIG. 5- Distribution of the SKG area before and some minutes after the fitting
of the alphs. Eyes open situation. N= 57, ns.
Note that the population is statistically abnormal (p < 0.001) according to
the area parameter, as from a clinical point of view.
FIG. 6- Distribution of the SKG area before and some minutes after the fitting
of the alphs. Eyes closed situation. N= 57, ns.
Note that the population is statistically abnormal (p < 0.02) according to
the area parameter, as from a clinical point of view.
FIG. 7- Distribution of the LFA parameter before and some minutes after the
fitting of the alphs. Eyes open situation. N= 57. There is a statistically
significant difference (p < 0.02) between the two distributions.
FIG. 8- Distribution of the LFA parameter before and some minutes after the
fitting of the alphs. Eyes closed situation. N= 57. There is a statistically
significant difference (p < 0.001) between the two distributions.
FIG. 9- Distribution of the VFY parameter before and some minutes after the
fitting of the alphs. Eyes open situation. N= 57, ns.
FIG. 10- Distribution of the VFY parameter before and some minutes after the
fitting of the alphs. Eyes closed situation. N= 57, ns.
Discussion
The
fitting of alphs on the vestibular face of the superior incisive teeth of these
´dental´ patients brought about a statistically very significant reduction of
the LFA parameter (length as a function of area) that evaluates the energy
expenditure required from the subject to control his orthostatic posture
(A.F.P., 1985; Nagayama et al., 1987; Vallier, 1994; Imaoka et al.,
1997). Thus a minimal oral stimulation is able to
modify the control of orthostatic posture in a very significant manner.
The
hypothesis seems therefore validated that stimulations of the jugal (and/or
lingual) mucosa due to the presence of the gutter could be responsible, at
least partly, of the effect of these prostheses on the control of orthostatic
posture.
Nothing
in this experience, indeed, allows us to assert that this jugal stimulation is
the only origin of the gutters recognized efficiency, but conversely it is no
longer possible not to take into account the effect of
this stimulation when tempting to explain the gutters beneficial role.
It
is possible that this effect of the alphs is not specific, simply in relation
with a modification of the subjects general vigilance
level. This remark however can also apply on gutters whose it has never been
demonstrated that they have a specific effect on the postural system.
More sure after this experimental work and its results, we
sought to evaluate therapeutic efficiency of the alphs on patients that suffer
from a postural deficiency syndrome (Da Cunha, 1987). Results of this
evaluation are not yet rigorously established but it seems possible already to
tell that alphs as gutters have a real efficiency to cure disorders of the fine
postural control system, and particularly those that demonstrate some relations
with abnormal occlusion.
And
even it seems that, in certain conditions, effects obtained by the fitting of
alphs vary systematically in function of the place where they are pasted; this
specific effect of the alphs on the functioning of the postural system would be
a novelty. But for the moment that is only a clinical feeling which deserves to
be verified.
CONCLUSION
A
very discreet mechanical stimulation of the labial mucosa, realised by a small
extra thickness pasted on the vestibular face of incisive teeth, brings about an
important, immediate and non specific modification of
the control of orthostatic posture. The conclusion of this experience, though
it is coherent with the non linear dynamic nature of
the fine postural control system, deserves being confirmed by other works
because it queries too many explanatory models of the therapeutic efficiency of
occlusal gutters.
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