Myofunctional appliances -activators /certified fixed orthodontic courses by Indian dental academy

MYOFUNCTIONAL APPLIANCES--
ACTIVATORS
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Definition of Myofunctional appliances
• A myofunctional appliance is defined as a loose fitting
or passive appliance which harnesses the natural
forces of the orofacial musculature that are
transmitted to the teeth & alveolar bone in a
predetermined direction through the medium of the
appliance.
• A functional appliance refers to a variety of appliances
designed to alter the arrangement of various muscle
groups that influence the function & position of the
mandible in order to transmit forces to the direction of
the basal bone. www.indiandentalacademy.com

Classification
I] Acc. to Profitt
1. TOOTH BORNE
Active appliances - elastic open activator,
Bimler’s appliance
Passive appliances - activator, bionator
2. TISSUE BORNE
Active appliances - Frankel’s appliance
Passive appliances - oral screen, lip bumper
II] Removable appliances - activator, bionator
Fixed appliances – Herbst appliance, Jasper Jumper
Semifixed appliances – Denholtz appliancewww.indiandentalacademy.com

III] Myotonic appliances – activator, bionator
Myodynamic appliances – elastic open activator,
Bimler’s appliance.
IV]Acc. to T.M. Graber,
Group A : Tooth supported – Catlan’s appliance
Group B : Tooth tissue supported – activator
Group C : Vestibular positioned [Frankel appliance,
vestibular oral screen].
V] Acc to Peter,
Classical – activator, bionator
Hybrid – double screen, Frankel’s hybrid appliance.

History of activators
• Normar Kingsley in 1879 devised
a vulcanite palatal plate to be
used in patients having a
retruded mandible. It consisted
of an anterior incline which
guided the mandible to a forward
position when the patient closed
on it.

• One of the first known
functional appliance known
as ‘Monobloc’ was
introduced by Pierre Robin
in Paris in 1926 for t/t of
patients with Pierre Robin
syndrome who suffered from
extreme retrognathia of the
mandible & as a result the
tongue is so far back in the
pharynx that there is risk of
suffocation.

• Viggo Andresen was not
satisfied with the orthodontic
treatment of his daughter, thus
tested the activator on her, who
was of vacation departure,
where she would remain for
three months. This Activator, a
modified Hawley device, with
an extra layer of vulcanite,
provoked a previous landslide
of the jaw when in occlusion.
After his daughter returned he
found marked correction of her
profile & class II malocclusion
only on nocturnal use of the
device.
Andresen-Haupl
appliance

Indications
• Class II division 1
malocclusion.
• Class II division 2
malocclusion.

• Class III
malocclusion.

• Class I open bite
malocclusion.
• Class I deep bite
malocclusion.

• As a preliminary
treatment before any
major fixed appliance
therapy.
• For post treatment
retention.
• Children with reduced
lower facial height.
REDUCED FACIAL HEIGHT
POST T/T RETENTION

Contraindications
• Correction of class I problems of crowded teeth
caused by disharmony between tooth size n jaw size.
• Children with excessive lower facial height & extreme
vertical mandibular growth.
• In children whose lower incisors are severely
procumbent.
• Children with nasal stenosis caused by structural
problems within the nose or chronic untreated
allergy.
• Limited application in non growing individuals.

Mode of action
• Acc. to Andresen & Haupl, the
activator induces a musculo-
skeletal adaptation by
introducing a new pattern of
mandibular closure.
• Most changes are instigated by
holding the mandible forward
[hyperpropulsion] by stretching
the muscles of mastication
which contract & thereby set up
a myotactic reflex.

• This reflex generates a
kinetic energy which has a
restraining effect on the
maxillary skeletal & dento-
alveolar growth & the
alveolar process distally.
• This in turn produces a
reciprocal forward force on
the mandible.
• In addition a condylar
adaptation by backward &
upward growth occurs.
• A 3rd factor is the force
generated while swallowing
& sleeping.
ACTIVATOR

Effects of activator on masticatory muscles
• The muscle activity of temporalis,
masseter & digastric muscles is
lower during sleep than during
daytime, irrespective of the use of
the activator.
• In sleep-time, temporal and
digastric muscle activity is
significantly decreased, although
masseter muscle activity presents
no significant differences.
• With the activator in use, the
digastric muscle activity tends to
increase in comparison with the
elevator muscles during daytime
and sleep. www.indiandentalacademy.com

• Although the activity of both
elevator muscles is
diminished by use of the
activator during sleep, some
subjects show an increase
during daytime.
• Activator should be used, not
only during sleep, but also
during daytime and clenched
on consciously to obtain the
adaptation and development
of the masticatory muscles for
the 're-training of the muscles'
at a new favourable
mandibular position.
KARWETZKY’S ACTIVATOR

Advantages of the activator
• Provides incisal capping.
• Oral hygiene is kept simple,
the dental braces can be
cleaned thoroughly outside
the mouth
• Helps in early treatment of
mixed dentition, especially in
cases of large discrepancies
between the upper and lower
jaw ( reduces risk of damage
to front teeth in the presence
of strongly protruding front
teeth or strongly layered front
teeth)

• Influencing the profile or
general harmony of the
face in a positive way by
steering growth and
working on the
musculature.
• The growth of permanent
teeth is not disturbed, the
device can be ground for
the purpose of steering
the growth of permanent
teeth.
• Slow “switch in function”
reduces the risk of
recurrence.

Disadvantages of the activator
• The position of individual teeth
can hardly be changed
• Partly detrimental side effects
on the position of front teeth
• Speech may be strongly
impaired
• The treatment takes longer
than with fixed devices
• Success depends on the
patient’s cooperation
(activators must be worn for 14
to 16 hours daily, sometimes
even permanently, in order to
achieve the optimum effect
WOODSIDE ACTIVATOR

• In cases of marked growth
deficits, the treatment is not
always successful
• Are practically inapplicable
in male adolescents (aged 13
to 14 years) in the main phase
of growth of the upper and
lower jaw because of poor
cooperation
• Damage or loss of the fixture
due to improper handling
• Given the predisposition, the
patient’s roots may be
shortened www.indiandentalacademy.com

Construction Bite
• Construction bite is an
intermaxillary wax record
used to relate the mandible
to the maxilla in the three
dimensions of space.
• It is used to reposition the
mandible in order to
improve the skeletal inter
jaw relation.
• Bite registration involves
repositioning the mandible
in a forward direction as
well as opening the bite
vertically.

• Degree of activation should
stretch the muscles of
mastication sufficiently to
provide a positive
proprioceptive response.
• Degree of activation should be
within physiologic range of
activity of muscles of
mastication, ligamentous
attachments & the TMJ.
• In most cases the mandible is
advanced by 4-5mm & the bite
is opened to the extent of 2-
3mm beyond the freeway
space

General considerations for construction bite
• In case the overjet is too
large, forward positioning
is done in 2-3 phases.
• In case of forward
positioning of the
mandible by 7-8mm,
vertical opening should be
slight to moderate, that is,
2-4mm.
• If the forward positioning
is not more than 3-5mm,
then vertical opening can
be 4-6mm.

Theories of bite registration
In the sagittal plane
• Single step advancement
• Progressive advancement
In the vertical plane
• Minimal vertical opening
• Moderate vertical opening
• Extreme vertical opening

• Characterised by marked
forward positioning of the
mandible but minimal vertical
opening
• As a rule of thumb anterior
advancement should not exceed
more than 3 mm posterior to the
most protrusive position.
• This kind of an activator
constructed with marked
sagittal advancement but
minimal vertical opening is a ‘H’
activator- indicated in class II
div 1 patients having horizontal
growth pattern.
Low construction bite with marked mandibular forward positioning

High construction bite with slight mandibular forward positioning
• Mandible is positioned
anteriorly by 3-5mm only and
the bite is opened vertically
by 4-6mm or a max. of 4mm
beyond the resting position.
• This kind of an activator
constructed with minimal
sagittal advancement but
marked vertical opening is a
‘V’ activator.
• Indicated in class II division 1
malocclusion.
V ACTIVATOR

Construction bite without mandibular forward positioning
• Sometimes a
construction bite without
forward position of the
mandible is made in
cases such as deep bite
and open bite.
DEEP BITE
OPEN BITE
ACTIVATOR FOR OPEN & DEEP BITE

Construction bite with opening and posterior positioning of
the mandible
• In class III malocclusion
a bite is taken after
retruding the mandible
to a more posterior
position.
• In addition the bite is
opened sufficiently to
clear the bite.
• In general a vertical
opening of 5mm & a
retrusion of 2mm is
required.
Class III malocclusion

Fabrication of an activator
Impressions
• Impressions of upper &
lower arches are made to
construct 2 pairs of
models:-
1. Study models
2. Working models
Class II div 2 model
Class III model
Class II div 1 model

Bite registration
• The amount of sagittal &
vertical advancement is pre
planned.
• The patient is made to sit in an
upright, relaxed & non strained
position.
• The mandible is guided to
desired sagittal position
merely by operator’s thumb &
forefinger without force or
pressure.
• Practice this positioning a few
times before registration of
the bite.

• Method 1
• Explain to the patient what is
required, that they posture the
lower jaw forward to the
required occlusion. Do not over
posture the patient or place
them into a class III
relationship.
• Soften 2-3 sheets of pink
modeling wax in hot water,
folding them into a horseshoe
shape.
• Place them into the patients
mouth and get them to close
into the postured position. You
must ensure that the centre
lines are correct.

• Remove the wax
registration and chill the
wax under cold running
water & try it on the casts.
• Cut away the wax as shown
in the canine/premolar
region.
• Place back into the mouth
to check the registration is
correct - the lateral
opening and that the centre
lines are correct.

Method 2
• Use either a thick or thin 'bite
fork'. The thick (yellow) ones
are for when an overbite needs
reducing and thin (blue) for
normal or reduced overbites.
• Explain to the patient what is
required, that they posture
forward to the required
occlusion.
• Place the bite fork into the
mouth and ask the patient to
practice biting into the
required position. Do not over
posture the patient or place
them into a class III
relationship.
Bite forks

• Soften a sheet of pink modeling
wax in hot water, folding them
into the bite fork.
• Place the bite fork and soft wax
into the mouth asking the
patient to close into the
postured position. Excess wax
can be moulded to aid location
of the bite for the laboratory.
You must ensure that the
centre lines are correct.
• Remove the bite fork and chill
the wax under cold running
water. Place back into the
mouth to check the
registration is correct.

Articulation of the model
• The wax bite registration is
placed on the occlusal
surface between the upper
and lower models.
• The models are then
articulated in a reverse
direction so that the
anterior teeth face the
hinges.
• This kind of articulation
ensures sufficient access
to the palatal surface of the
upper and lingual surface of
the lower models during
fabrication of the appliance.www.indiandentalacademy.com

Preparation of wire elements
• Usual design requires an
upper labial bow made
with 0.8 or 0.9mm wire and
consists of horizontal
section with two vertical
loops.
• Ends of the vertical loops
enter the acrylic body
between the canine and
deciduous first molar (or
first premolar).
• Labial bow can be active or
passive. www.indiandentalacademy.com

Fabrication of the acrylic portion
a. Maxillary part
b. Mandibular part
c. Inter-occlusal part
• The appliance can be
fabricated either by using
heat cure or cold cure resin.
• In case of heat cure models
are first waxed and then
flasked.
• Appliance consists of three
parts:-
ELASTIC OPEN ACTIVATOR

Management of the appliance
• Patient should be sufficiently convinced about the
benefits of using the activator.
• The patient is taught how to use, place & remove the
appliance by himself.
• Usually the patient is asked to wear the appliance 2-3
hours a day during the day time for the first week. During
the second week the patient is asked to wear it for three
hours during the day as well as while sleeping. In case he
has difficulty in using it whole night, more day time use is
prescribed till he can use it for the entire night.
• A trimming plan should be developed based on the
individual needs of the patient.

Trimming of the activator
• Planned trimming of the
appliance in tooth contact area
is carried out to bring about
dento-alveolar changes so as
to guide teeth into good
relation in all three planes of
space
• The acrylic surfaces that
transmit the desired force by
contact with the teeth are alled
guide planes.

For vertical control
• INTRUSION: In incisors it is
achieved by loading the incisal
edge of these teeth with
acrylic.
In case intrusion of posteriors
is needed then only cusp tips
are loaded with acrylic. Fossae
& fissures are free of acrylic.
• EXTRUSION: In incisors &
molars the lingual surface is
loaded above the area of
greatest convexity in the
maxilla & below the area of
greatest convexity in the
mandible.
FOR INTRUSION IN
VERTICAL PLANE
FOR EXTRUSION

For sagittal control
• PROTRUSION: In case incisors are
to be protruded lingual surface of
the teeth is loaded with acrylic
and a passive labial bow is given
that is kept away from the teeth to
provent perioral soft tissues
contacting the teeth. It can be of
two types:
a. Entire lingual surface is loaded
b. Only incisal portion of lingual
surface is loaded
• RETRUSION: The acrylic is
trimmed away from the lingual
surface & an active labial bow is
used to bring about retrusion of
the incisors.
FOR PROTRUSION
FOR RETRUSION

Movement of posterior teeth in a
sagittal plane
• Teeth in the buccal segment
can be moved mesially or
distally to help treat class II &
III malocclusion.
Movement of teeth in transverse
plane
• Stimulation of expansion of the
buccal segment is done by
allowing the contact of acrylic
on the lingual surfaces of teeth
to be moved transversely.
• Jackscrew type activator
provides better expansion.
Jackscrew activator

TWIN BLOCK APPLIANCE
• Indicated for following
malocclusions: Class II Division
I; Class II Division 2; Class I
open bites; Class I closed bites;
Class III; Lateral arch
constriction and
anterior/posterior arch length
discrepancies (can also be
used effectively in TMJ therapy).
• Separate, unattached upper
and lower components allow
mandible to move normally in
anterior and lateral excursions
without being restricted by a
bulky one-piece appliance
UPPER TWIN BLOCK
LOWER TWIN BLOCK

• Versatile design allows
you to control and correct
upper and lower arch
width and length
independently, at the
same time that skeletal
changes are being made.
• Patient can eat and speak
normally - movements of
the tongue, lip and
mandible are not
restricted

• The Twin Block's high comfort
level allows it to be worn 24
hours a day - even while
eating. This versatile design
allows you to take advantage
of all the functional forces
applied to the dentition during
mastication (faster results
and shorter treatment times).
• Patient appearance and
profile are noticeably
improved immediately. This is
an excellent patient
motivator.

• The use of functional jaw
orthopaedics, at the
correct time during
growth, can ultimately
result in maloccluded
patients achieving a broad,
beautiful smile, an
excellent functional
occlusion, a full face with a
beautiful jaw line and
lateral profile and, most
important of all, a stable
and healthy
temporomandibular joint

• Unlike bulky, one-piece
functional appliances, the
Twin Block has separate,
unattached upper and lower
bite block components -
actually two appliances
which work together as one.
In function, these two
appliances interlock at the
70 degree angle set into the
bite blocks and posture the
mandible forward into the
ideal Class I position preset
by your wax registration.

• The Twin Block Appliance has
been described as "the most
comfortable and the most
esthetic of all the functional
appliances."
• The Twin Block does not
contain anterior wires or
cheek and lip pads. Lingual
extensions are eliminated
ensuring patient comfort.
• The patient can eat and speak
normally - movements of the
tongue, lip and mandible are
not restricted.
Patient acceptance

• The high comfort level allows
the appliance to be worn 24
hours a day. This harnesses
the forces of occlusion and
mastication, leading to faster
results and shorter
treatment times.
• Patient appearance and
profile are improved
immediately.

Conclusion
• Functional appliances are
usually fitted to reduce the
prominence of upper incisors
and to improve the way the teeth
bite together.
• Two removable appliances, one
over the top teeth and one over
the bottom teeth, alter the bite of
the teeth by holding the lower
jaw forwards.
• These braces may be in one
piece (eg Medium opening
activator) or in two separate
parts (eg Twin Blocks).
Before treatment

• Functional appliances should
be worn on a full-time basis,
day and night, for about 9
months. They must be removed
for cleaning, swimming and
contact sports. After this initial
treatment period they are
usually worn at night times for
about a year.
• Further orthodontic treatment
with fixed braces may
be needed after functional
appliance treatment. In these
cases headgear may be
needed at night times and the
total course of treatment may
last 30 months.
After treatment

ONLY A
PERFECT
SMILE … …
MAKES A
PERFECT
PICTURE ! ! !
THANK - YOU
For more details please visit

Myofunctional appliances -activators /certified fixed orthodontic courses by Indian dental academy

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