original work

Early myofunctional
approach to skeletal
Class II
C. Quadrelli
M. Gheorgiu
C. Marchetti
V. Ghiglione
University of Studies of Milan
Clinic of Odontology and Stomatology
Institutes of Clinical Professional
Specialization
Director: Professor F. Santoro
Division of Clinical Orthognatodontics
And Electromyography
Head of Department: Professor V. Ghiglione

Key Words:
Skeletal Class II
Early treatment
Soft tissues dysfunctions

Introduction
Therapy aimed at skeletal Class II subjects is carried out at the
Odontology Clinic of Milan University in accordance withstudies conducted by Petrovic and Stutzmann (12, 13), with an
initial orthopaedic phase focussing on condylar growth. Such atherapeutic phase is made to coincide with the peak of
pre-pubertal growth, which we have identified by evaluating
skeletal age by X-raying the wrist and hand, following themethod according to Gianní (5). This is performed for the purpose of obtaining the greatest possible growth period, coupled
to an acceptable duration of therapy.
This ideal age to start treatment corresponds, in our studies, tonine years of age plus or minus one year. Younger children alsocome to be observed, mainly through the screening visit thatthey undergo at about six years of age (the onset of change ofdentition). During this phase, although treatment is mainly
directed towards identifying cross-over bite and resulting
asymmetries (interceptive orthodontics), a large number ofskeletal Class II children are noticed whose orthopaedic
therapy is postponed until they reach nine years of age. A large

Abstract - Early myofunctional approach to skeletal Class II
We analysed the effects of the Pre-Orthodontic Position Trainer in skeletal development,
muscle function, tongue function, breathing and bruxism in skeletal Class II patients. This
one-year therapy prepares for usual orthopaedic Class II treatment in patients with soft tissue dysfunction or bruxism and should be adopted before peak pre-pubertal growth; theideal age is 4 - 9 years.
The results of the treatment were analysed by means of clinical, radiological, electromyographical, kinesiographical, stabilimetric and rhinomanometric evaluations and the measurement of arch diameter using plaster models. The cases described in this pilot study
demonstrate the efficiency of this early myofunctional therapy in patients in skeletal Class II.

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C. Quadrelli, M. Gheorgiu, C. Marchetti, V. Ghiglione

number of skeletal Class II dismorphosis also
displays disorders or parafunctions of the soft
tissues of the stomatognatic apparatus.
These cases have been classified into two
reasonably homogenous groups:
the first, Group A, is characterised by:skeletal Class II, dentoalveolar open bite, lingual malposition and atypical deglutition;
the second, Group B, is characterised by:skeletal Class II, dentoalveolar deep bite andbruxism.
Both groups are composed of patients with
non-obligatory oral respiration.
It was decided to subject these two groups toearly pre-orthopaedic treatment aimed at
resolving dysfunctions through gentle, but
active, inducement of the protruding mandibular position (14, 15). Our aim was that ofevaluating with ex adiuvantibus criteria theclinical efficacy of this early intervention, towhich this pilot report refers.
In future, these patients will be compared, forevaluation purposes, after classic orthopaedic
Class II treatment, with patients having
received only Class II orthopaedic treatment at
the age of nine, plus or minus one year. The
purpose of this practice is to also evaluate
statistically and not only from a clinico-empirical point of view, the efficacy of this early
therapeutic approach.
At the same time, the purpose of this preliminary report is to highlight possible relationships between skeletal Class II, dysfunctionsof the soft tissues, parafunctions, oral respiration and the general posture of the subject.

••

Electromyography, Stabilimetry,
Rhinomanometry
A qualifying characteristic of the approach toorthodontic patients is that of defining a diag-

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nosis and treatment plan, with particularreference to function, while considering
dentition not only within the mouth, but also
in relation to other organs and systems, inadherence to Gianní’s indications (5), so tofollow a holistic approach to the patient. For
this reason, we consider appropriate the useof electromyography, stabilimetry and rhinomanometry, particularly during the patient’s
growth period when the correct relationshipbetween the various systems acquires significant importance in the control of growth of
the stomatic structures (10).
The balanced development of the transverse
diameter of the upper jaw, for example, ispositively influenced by correct nasal respiration (16), hence the necessity of evaluating
this function through rhinomanometry.
A properly designed therapeutic plan should
thus take into account the possible need toreprogram respiration from oral to nasal.
Muscles inserted into the maxillary bone must
function correctly for normal development of
this bone. The active movement of themandible by the external pterygoid muscles isdetermined by activating condylar growth (12).
Electromyography allows detection of
possible muscular malfunctions and putting
corrective treatment into place. Furthermore,
electro-myography allows to determine
whether a brace to correct the mandibular
position stimulates the external pterygoid
muscles and whether it will be useful inencouraging condylar growth.
Stabilimetry allows the detection of overall
postural improvements whenever an intervention is made to regularise the balanced growthof the maxillaries.
It is also quite probable that the correction oforal respiration could contribute, by normalis-

Class II Skeletal

ing the function of the relevant muscles, toimprove the general posture and not only thegrowth of the maxillaries.
Taking the above into consideration, we
thought it opportune to intervene in skeletal
Class II anomalies before the age of peakgrowth, until now considered the most suitable
for solely activating condylar growth.
Pre-Orthodontic Position Trainer
It was decided to initiate Class II orthopaedic
therapy not only at an earlier age, but also aiming to correct functional problems concerning
soft tissues, such as lingual malposition, thecentripetal thrust of lips and cheeks, as well as
oral respiration and bruxism. To this aim, ourattention was drawn to the Pre-Orthodontic
Position Trainer (fig. 1), a functional device
usable in children from the age of four to ten
years and recommended for correcting:– the interposition of lips between dental arches;– atypical swallowing;– the centripetal thrust of cheeks upon thedental arches;– to discourage oral respiration;– to avoid bruxism;– to favour the action of the external
pterygoids and thus encourage the active pushof the mandible.
Therefore, the trainer encourages transversal
bone growth (7, 11) by acting as a “shield” forthe cheeks; it brings about muscular relaxationand protection of teeth and articulations frombruxism, by virtue of the “bite effect”. It
determines the correction of skeletal Class II
thanks to active mandibular forcing and by
distancing the lower lips from the dental alveolar arch it prevents malpositioning of the

tongue and lower lip during swallowing, thus
solving the associated dental open bite. It also
promotes nasal respiration.

Material and Methods
Clinical Cases
Six children have been treated, four boys andtwo girls, ranging in age from four years andnine months to nine years and one month. Threechildren, affected with skeletal Class II, dental
alveolar open bite, lingual malposition, atypicalswallowing, non-obligatory oral respiration,
were classified as Group A. Three children,
displaying skeletal Class II, First Division, deep
dental alveolar bite, bruxism and non-obligatory oral respiration, were classified as Group B.

Diagnostic Criteria
The following were used as diagnostic criteria:
1) Standard objective examination, as at thescreening visit adopted for the sixth year of age
2) Orthopantomography, latero-lateral teleradiography of the cranium and radiography of
the wrist and hand to determine skeletal age,according to Gianní (6).
3) Electromyography (fig. 2). Recourse to asurface electromyography (3) permits the
scrutiny of muscular function through therecording of electrical potentials generated by
the simultaneous contraction of a number ofmuscle cells, defined as the potential of the
motor unit. Every change in nerve or muscle
fibres induces a change of that potential of the
motor unit. Studies of experimental andclinical electromyography have demonstrated
a linear relationship between the tension of amuscle in isometric contraction and thevoltage produced. This voltage is proportional

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C. Quadrelli, M. Gheorgiu, C. Marchetti, V. Ghiglione

Fig. 1a, b - Pre-Orthodontic Position Trainer: 1) guide for tooth alignment; 2) protection against malposition of lips andcheeks; 3) guide for the proprioceptive localization of the tongue; 4) protection against lingual malposition; 5) lip
bumper; 6) double groove into which the teeth can be placed while lips are closed to prevent oral respiration. Also
gives protection in cases of bruxism.
Fig. 2a, b - Surface electromyography.
1a

2a

1b

2b

to the tension of the muscle and also to thenumber of motor units called into play. It thus
follows that the voltage measurement derived
from one muscle represents a reliable index
relating to the efficiency of that muscle or,more precisely, of the number of motor units
called upon by that muscle to obtain a contraction. As muscle fatigue reduces the contractile efficiency of the motor units, the112 2/2002 MONDO ORTODONTICO

fatigued muscle must recruit additional motor
units to perform the same amount of work, thus
producing additional current. Also, muscles inspasm (pathological isometric contraction)
recruit an increased number of motor units
because the fibres in spasm are not available
for a physiological isotonic contraction.
The electromyography employed consists of aneight-channel preamplifier, with filters to isolate the patient from possible current dispersions through the power supply. The channels
are connected to corresponding cutaneous electrodes thus enabling the simultaneous recordingof the electrical activity of four or eightmuscles (masseter, anterior and posterior
temporals and digastrics). Furthermore, a main
computer with microprocessor is capable ofconverting the data relative to the electricalactivities of each muscle explored from analogue to numeric. A printer provides a hard
copy of the data in both graphic and numericform. Electrical potentials are gathered by

Class II Skeletal

Fig. 3 - KinesiographFig. 4 - Rhinomanometer
Fig. 5 - Stabliometric Platform

3

4means of adhesive electrodes using an electroconductive gel. The methodology described isderived from that structured by Jankelson (9,10).
4) Kinesiography with the kinesiograph interfaced to the electromyograph (4,9) (fig. 3).
The specialised software used is capable ofevaluating both the muscular condition andthe kinematics of the patient’s mandible. It is
specifically used to investigate the patient’s
mandible and at the same time to evaluate theideal trajectory of myocentric occlusion (ideal
physiological occlusion that occurs in theabsence of muscular spasm). The kinesiographcan measure movements in aperture, closure,laterality, protrusion and retrusion of themandible, in the three spatial planes. It canalso allow the study of velocity by exploring
the principle of magnetic fields. To this aim, asmall magnet is secured with special adhesiveat the level of the central inferior incisors andmade to act within a preset magnetic field.
Magnetic field variations, caused by the magnet following the movement of the mandible,
are recorded by sensing equipment secured
around the patient’s face. The millimetre
graduated screen of an oscilloscope displays a5

trace corresponding to the movement of themagnet in the preset magnetic field, allowing
the localization of the incisive mandibular
point. Through a kinesiographic examination,
it is possible to assess dysfunctions, record theideal neuromuscular occlusion and thediscrepancy between the latter and the normal
centric occlusion, always in adherence with
Jankelson’s indications (9, 10).
5) Rhinomanometry (2, 6, 8) basal and after
exertion to distinguish obstructions of an
anatomic nature from those of inflammatory
nature (fig. 4).
6) Stabilimeter readings (1) with open eyes,with closed eyes and during deglutition on
stabilimeter support (fig. 5).
7) Measurement of intercanine cusps (cusp tocusp) and intermolar cusps (from mesiobuccal
cusp to the cusp of the first molars) of theupper arch (7, 11).
Therapeutic Methodology
The Pre-Orthodontic Position Trainer was theappliance used.
For Group A the soft “blue” type, for Group B
the hard “red” type, but not used in succession,

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C. Quadrelli, M. Gheorgiu, C. Marchetti, V. Ghiglione

as dental alignment was not sought as recommended by the manufacturers. Dental alignment does not concern us during thistherapeutic phase. Therapy was carried out fora year, with the appliance worn all night andafternoon for an overall total of sixteen hours
per day. An additional series of simple
myotherapy exercises repeated ten times, with
the Pre-Orthodontic Position Trainer fitted,
were carried out in the morning, afternoon andevening. The exercises consisted of:1) positioning of the tip of the tongue on the
lingual support of the appliance, closing lips
and swallowing while holding the appliance inplace;
2) with the tongue still in the position
described above, closing the lips and breathing
through the nose;

Results
Diagnosis
The following observations can be extrapolated at diagnostic level:1) Scan 9 in electromyography displays thatGroup A shows, at rest, higher potentials in
temporals than in the masseters and reduced
electrical activity in the masseters in absolutevalues, thus hypotrophic. Scan 11 shows,during functional activity (alternate clenching
and relaxation of the mandible in habitual
occlusion, followed by the same actions on
cotton rolls), a low electrical output but with
sufficient permanence in time. Electrical
output is greater on the rolls, a sign of alteredvertical dimension. Group B has typically, andhere more markedly, an inversion of electricalvalues with a predominance of the temporals
over the masseters, that however have normal
electrical output at nominal values, thus

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normotrophic, and an equal force on both thecotton roll and in habitual occlusion, a sign offree interocclusal space not being correct.
2) The kinesiographic exam highlights averticality defect, evident in Group B, withloss of free interocclusal space.
3) Rhinomanometry shows a scarcely significant behaviour, with normal patency or modest
reduction of patency of the nasal fossae in allcases, but marked in one. However, improvement occurred during the stress test showing,in this case, the absence of actual anatomic
obstructions, but only problems of an inflammatory nature. Also with reference to casehistories, previous inflammatory episodes of
the upper respiratory tract are found,particularly in children between the years of
three and seven, coincident with school age.
4) The stabilimeter exam does not reveal specific pathological alterations of the overall
posture, except in one case, where changes
seemed attributable to the position of themandible. However, in all cases, a certain
non-specific difficulty to maintain verticalforces on the projection of the centroid arenoticed and a wide and irregular bundle ofoscillations is displayed, meaning the centreof the mass is somewhat lateralized.
Therapy
At therapeutic level in both groups, normalization of the dental skeletal Class, withimprovements of the skeletal class, withaverage reduction of the ANB angle of 1.5º. In
Group A closure of the dental open bite isachieved, while Group B shows a slight
improvement of the overbite. The dento-skeletal improvement appears more noticeable inGroup A cases with open bite due to lingual
malposition. The electromyography emphasizes, for Group A, a normalization of values
in Scan 9, with an increase of potentials

Class II Skeletal

generated by the masseters and an improvement of contraction force during habitual
occlusion as compared to the contraction on
the cotton roll of Scan 11.
Scan 20 shows normalization of the functionof the suprahyoid muscles used in physiological deglutition, with symmetric potentials
within the norm of absolute values. Group B
shows a reduction of potentials generated by
the temporals and a normalization of therelationship between temporals and masseters.
The physiological prevalence of the latter isthus proof of results obtained on bruxism.
The kinesiographic exam of Group B displays
normalization of interocclusal free space.
Rhinomanometrics do not show noticeable
improvements. Stabilimeter readings show
improvement in maintaining the baricentre
position on the vertical plane for both groups.
Measuremt of diameters of intercanine andupper intermolar shows an increase in the latter.

Discussion
The clinical and instrumental evaluation of thetwo groups of patients confirms that therapyof Class II patients having soft tissue dysfunctions or parafunctions show improvement afterusing the Pre-Orthodontic Position Trainer
for one year. The following is achieved:
1) Normalization of the muscular function,evident and complete in both Group A and B,
together with resolution of atypical deglutitionand control of bruxism;
2) Improvement of the dental structure.
Evident and significant in Group A withclosure of open dental bite. Less marked inGroup B with reduced aperture of bite andimprovement in tooth crowding;3) A modest result at skeletal level, median
reduction of the ANB angle of 1.5º, comparable in Groups A and B;

4) Unchanged patency in the nasal fossae, but
improved aptitude towards nasal respiration
with respect to non-obligatory oral breathing;5) Influence upon the overall body posture:
improved capability to maintain the projectionof centre of mass on the vertical;
6) Intercanine and intermolar diameters:
increased only in the intermolars with modest
improvement of crowding of frontal teeth,
when of a significant degree.

Conclusions
This study is a preliminary report the purposeof which is to clinically evaluate the therapeutic efficacy of the Pre-Orthodontic Position
Trainer. The subjects analysed here, after further Class II orthopaedic therapy with rapid
expansion of the palate and mandibular
impulsion, will serve as cases for comparison
with controls treated only with Class II
orthopaedics and not preceded by the PreOrthodontic Position Trainer phase. The
clinical results illustrated above lead us tobelieve that it would be correct to bringforward by a year the therapy specifically
aimed at eliminating those dysfunctional andparafunctional factors of the soft tissues that
can interfere with the mandibular growth andpromote correct deglutition, correct nasal
respiration and elimination of pathologicalmuscular contractures. The device is welltolerated by small patients, does not require
collaboration different from that necessary for
a common brace and requires fewer speechtherapy sessions. As a result, the trainerdelivers patients ready to start Class II
therapy, free from muscular d y s f u n c t i o n s o r
p a r a f u n c t i o n s , a l r e a d y accustomed to a
prolonged and active posture of the mandible.
Furthermore, this intervention would seemMONDO ORTODONTICO 2/2002 115

C. Quadrelli, M. Gheorgiu, C. Marchetti, V. Ghiglione

appropriate in preventing abnormal postural
attitudes of the face typical of skeletal Class II.

Clinical Cases
Case number 1 (Group A)
Male patient MM of seven years and eightmonths, of skeletal Class II (fig. 6a), ANB angleof 11.2º (fig. 6b), infantile deglutition, lingual
malposition, open dental bite with a OVB of 0.7 mm and moderate dental crowding.
The electromyography shows (Fig 6d) a
reduction of the contractile force of the masseters, displaying a hypotrophic nature, and an
improved recruitment of fibres during contraction on the cotton roll with respect to that inhabitual occlusion.
Rhynomanometrics show normal patency of thenasal fossae (fig. 6e), though in the presence oforal respiration, is interpreted as an abnormal
habit following repeated episodes of inflammation of the upper respiratory track in the past.
Stabilimeter output (fig. 6f) measurements arewithin the normal range although difficulty isshown in keeping the projection of the centre of
the mass on the vertical.
Therapy lasted from December 1999 to
February 2001 and was carried out with the
Pre-Orthodontic Position Trainer (colour blue,soft) (fig. 1) worn for about sixteen hours a day
and in association with myotherapy exercises.
Final examinations show a more harmonious
profile (fig. 6a), reduction of ANB to 9.8º
(fig. 6b), gain of the OVB up to 0.6 mm,
closure of the dental open bite and improvement of the molar and canine class (fig. 6c).
Electromyography displays in Scan 9 normalization of the absolute values of the potentials
generated by the masseters, which also appear
normotrophic, with physiological dominance of

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the masseters over the temporals. Scan 11
reveals normalization of the capability ofrecruitment of fibres in contraction during
habitual occlusion, force that now prevails overthat of contraction over the cotton roll (fig. 6d).
The suprahyoids, and particularly the digastrics,
appear symmetrical with normal potentials in
absolute value in Scan 20. This corresponds toattaining a normal physiologic deglutition.
The rhinomanometric examination appears tobe substantially unchanged except for a veryslight improvement in the patency of the nasal
fossae (fig. 6e). Stabilimetry reveals that thecentre of the pressor force of the feet can besuperimposed on the centroid of vertical forces(fig. 6f). Measurements on the plaster models
show an increase only of the upper intermolar
diameter of 1.5 mm, with that of the upperintercanine unvaried.
Case number 2 (Group B)
Female patient GG, of nine years and one
month, of skeletal Class II (fig. 7a), ANB
angle of 6º (fig. 7b), deep dental bite with
OVB equivalent to 6 mm, marked crowding
borne by the incisors (Fig 7c) and bruxism.
The electromyography shows in Scan 9
predominance of hypertonic temporals overthe masseters, also hypertonic, a situationcompatible with deep bite and bruxism, while
Scan 11 shows that biting on the cotton roll
generates an increased electrical output
greater than the norm and equal to theelectrical output during closure in habitual
occlusion. This denotes incorrect freeinterocclusal space, with a possible loss offree interocclusal space. Predominance of thetemporals remains (fig. 7e). Rhinomanometryshows obvious obstruction of flow with reduced
patency of both nasal fossae (fig. 7f).
Stabilimetry shows irregularity in the ball of
the foot with difficulties in maintaining theClass II Skeletal
Fig. 6a-f - Patient MM. a) profile before and after therapy;b) cephalometric diagram before and after therapy; c)overject and dental overbite before and after therapy; d)electromyography before therapy, Scan 9 and Scan 11;
and after therapy, Scan 9, 11; e) rhynomanometry before
and after therapy; f) stabilimeter measurements before
and after therapy.

6a

6b

6c

6d

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C. Quadrelli, M. Gheorgiu, C. Marchetti, V. Ghiglione
Fig. 6a-f - Patient MM. a) profile before and after therapy; b) cephalometric diagram before and after therapy;c) overject and dental overbite before and after therapy;d) electromyography before therapy, Scan 9 and Scan
11; and after therapy, Scan 9, 11; e) rhynomanometry
before and after therapy; f) stabilimeter measurements
before and after therapy.

6d

6e

6f

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Class II Skeletal
Fig. 7a-f - Patient GG. a) profile before and after therapy; b) cephalometric diagram before and after therapy;c) overject and overbite before and after therapy; d)electromyography before and after therapy; e) rhynomanometry before and after therapy; f) stabilimetermeasurements before and after therapy.

7a

7b

7c

7d

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C. Quadrelli, M. Gheorgiu, C. Marchetti, V. Ghiglione
Fig. 7a-f - Patient GG. a) profile before and after therapy; b) cephalometric diagram before and after therapy;c) overject and overbite before and after therapy; d)electromyography before and after therapy; e) rhynomanometry before and after therapy; f) stabilimetermeasurements before and after therapy.

7d

7e

7f

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Class II Skeletal

projection of the centroid of the mass on thevertical (fig. 7e) even though the results arewithin the norm.
Therapy lasted from September 1999 to March
2001 using the Pre-Orthodontic Position
Trainer (colour red, hard, for bruxism) worn for
sixteen hours a day, together with specificmyotherapy exercises.
Final examination shows: improvement ofskeletal Class II with more regular profile(fig. 7a), and reduction of angle ANB to 5º(fig. 7b).
Improvement of the occlusal relationship at
canine and molar level, but modest effect on
crowding and reduction of the OVB to 5 mm
(fig. 7c).
Electromyography (fig. 7d) shows in Scan 9 thenormalization of the temporal/masseter relationship, with physiologic prevalence of themasseters. This suggests that control over bruxism has been obtained. Scan 11 displays a dropin closure force upon the cotton roll as compared to that needed for habitual occlusion,indicating a probable recovery of physiologic
interocclusal free space.
Rhinomanometry does not show improvements(fig. 7e).
Stabilimetry demonstrates perfect centering of
the projection of the centroid vertical forces
upon the vertical plane, in perfect coincidencewith the centre of pressure of the feet (fig. 7f).
Measures on plaster models do not show anincrease of either the intercanine or the intermolar diameter and no improvement of dental
crowding is apparent.
Summary
The effects of the Pre-Orthodontic Position
Trainer on the stomatognatic system in Class IIwith soft tissue dysfunctions or parafunctions area n a l y s e d . T h e t h e r a p y, l a s t i n g o n e y e a r,

precedes and prepares for normal Class II
orthopaedic therapy and is carried out at an
earlier age coincident with the pre-pubertal
growth peak. Ideal age is between four and nine
years of age.
The results of the treatment are analysed bymeans of clinical, radiological, electromyographical, kinesiographical, stabilimetrical,
rhyno-manometric evaluations and measurementsof arch diameters using plaster models. The pilot
cases, described and commented on, show theefficacy of carrying out a myofunctional therapeutic approach on skeletal Class II subjects at
an early age.

Key Words
Skeletal Class II
Early treatment
Dysfunctions of soft tissues and parafunctions
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Received in editorial office October 2001
Carlo Quadrelli
Via Bixio 421013 Gallarate (VA)
tel. 0331 777261 - 305422
fax. 0331 777261
e.mail: c.quadrelli@libero.it