Activator and its modifications /certified fixed orthodontic courses /certified fixed orthodontic courses by Indian dental academy

ACTIVATOR AND ITS
MODIFICATIONS
INDIAN DENTAL ACADEMY

Leader in continuing dental education
www.indiandentalacademy.com


Catch them Young

ACTIVATOR AND ITS
MODIFICATIONS…
Watch them Grow


History…
Kingsley(1879) –
“ jumping the bite ”
Robin 1902- Monobloc.
Viggow Andresen (1908)
Andresen and Haupl (1955)
- Activator.

Mechanism of Action…

 MECHANISM OF THE STRETCH (OR) MYOTATIC
RELEX:





How does it work?
Monosynaptic?
Postural rest position?
Isometric contractions?

My View…




Harvold and Woodside ,Herren ,Selmer-Olsen



viscoelastic properties of soft tissue



Rationale?


 Bite registered for 3mm to 4 mm distal to the most protruded
position is to avoid the possibility of initiating Golgi tendon
organ activity and thus eliminate any undesirable myotatic reflex
 Witts supported a combination of isometric muscle contractions
and viscoelastic properties being responsible for the forces
delivered by the activator and used intermediate construction
bite height.
 Eschler attributed the muscle contraction to proprioceptive
stretch reflexes and observed the occurrence of both isometric
and isotonic contraction with use of the activator.

Types of forces in activator therapy
 Forces employed in activator therapy are categorized as,
 The growth potential, including the eruption and migration of
teeth, produces natural forces; these can be guided, promoted
and inhibited by the activator.
 Muscle contractions and stretching of the soft tissues initiate
forces when the mandible is relocated from its postural rest
positions by the appliance. Whereas forces may be functional in
origin, the activation is artificial.


Artificially functioning forces can be effective in three planes
Sagittal plane:
 Mandible is propelled down and forward.
 muscle force is delivered to the condyle and a strain is produced
 Slight reciprocal force can be transmitted to the maxilla during
this maneuver.
Vertical Plane:
 Teeth and alveolar processes are either loaded with or relieved of
normal forces.
 if construction bite is high, a great strain is produced
 if transmitted to the maxilla, these forces can inhibit growth
increment and direction and influence the inclination of the
maxillary base.

Transverse plane:
 Forces can be created with midline corrections.
 Various active elements like springs, screws can be built in to the
activator to produce an active biomechanical type of force
application.
The mode of force application, magnitude and direction depend
on the three dimensional dislocation of the mandible, which is
determined by the construction bite.

Activator
 The original appliance
consists of a combined upper
and a lower plate at the
occlusal plane only one-wire
elements was used i.e. A
labial arch for upper anterior
teeth.


Construction Bite
♫ Edge-to-edge incisal
relationship to stimulate the
mandibular growth. The
construction bite for the
activators was taken with the
lower jaw in class I or over
corrected class I molar
relationships
♫ Vertical opening not beyond
rest position of the mandible

EFFECT OF ACTIVATOR TREATMENT
 Skeletal ChangesClass II Div I)


The Skeletal effect of the activator depends on growth potential.



Two divergent growth vectors propel the jaw bases in an
anterior direction.

 The sphenoccipital synchordrosis moves the cranial base and
nasomaxillary complex up and forward
 The condyle translates the mandible in a downward and forward
direction.



In contrast to primary cartilages (epiphyses, sphenoccipital
synchondroses) a condylar growth is regulated to a high degree
by local exogenous factors.



Petrovic - forward posturing of the condyle activates the
superior head of LPM and condylar growth.



The activator can, to a limited degree control the upper growth
vector supplied by the sphenoccipital synchondrosis, which
moves the maxillary base forward.



Total anterior facial height increases with lower facial height
increased by more than twice as much.


ROLE OF RETRODISCAL PAD:
 The Retrodiscal pad controls mandibular growth in two ways.
 The vascular component controls the condylar cartilage growth
rate and endochondral ossification rate.


An increase in interactive activity of the retrodiscal pad
produces an increase in condylar cartilage growth and
endochondral ossification.


 An increase in interactive
activity of the retrodiscal pad
-accentuation of the ramus
posterior concavity and a
local increase in bone
apposition and the number
of negative charges at the
ramus posterior concave
surface.
 Accentuation of the ramus
anterior convexity and local
increase in bone resorption
and number of positive
charges at the ramus
posterior convex surface.

Dento Alveolar Effect
♫

The improvement in sagittal occlusal relationship was due
about equally to skeletal and dental charges.

♫

Overjet correction- mandibular growth exceeding maxillary
growth and distal movement of the maxillary incisors.

♫

Class II molar correction -mandibular growth exceeding
maxillary growth and mesial movement of the mandibular
molars.


♫ Inhibits maxillary growth, move the maxillary incisors and
molars distally and move the mandibular molars and incisors
mesially.
♫ Lingual tipping of maxillary incisors and labial proclination of
the mandibular incisors related to significant reductions in
overjet. Thus passive upper labial wire of activator intended to
avoid upper incisor tipping and acrylic cap on the incisal third of
the lower incisors can prevent proclination


Soft tissue changes
 Retraction of upper anterior teeth, followed by a similar
dropping back of the upper lip, improve a protrusive profile.
 Stoner’s and associates found that,
 Soft tissue improvements were produced by four principal
changes.
 The gross movement of incisors
 A reduction in the curl of the lower lip.
 Vertical opening of the chin.
 Forward positioning of the chin.
 Reduction of overjet has the effect of uncurling both lips, which
enables the lips to hold together without undue effort.

 Class II Div 2 malocclusions
 The upper central incisors are tipped labially by springs at the
incisal margin.
 The labial bow exerts lingual pressure at the labial gingival
margins to achieve lingual root movement.(Herren activator
preferred)
 Open bite and Cross bite?


REVERSE ACTIVATOR

 Construction bite
 Bite is taken by retruding
the jaw. The extent of
vertical opening depends
on the retrusion possible.


In Functional Protrusion Class III
Malocclusion
 The mandibular incisor hit prematurely in an end-to-end contact,
and the mandible then slides anteriorly to complete the full
occlusal relationship.
 The vertical dimension of construction bite is opened far enough
to clear the incisal guidance, which eliminates the protrusive
relationship with mandible in centric relation.
 The prognosis for pseudo class III malocclusion is good,
especially if therapy is started in early mixed dentition. In early
mixed dentition period, skeletal manifestation are not usually
severe, since the malocclusion develops progressively.

Appliance
 Mandibular labial bow is
used to guide the
mandible distally, as the
teeth occlude.
 The maxillary labial bow
If needed kept away
from labial surfaces to
relieve any lip pressure.

 The acrylic was relieved on
lingual surface of mandibular
incisors and maxillary
incisors supported with close
contact.
 Maxillary incisors are tipped
labially with small screws,
wooden pegs (or) lingual
springs (or) by application of
gutta percha lingual to
incisors.
 Concurrently force was
eliminated in the upper arch
with maxillary lip pads to
allow the fullest extent of
growth potential

 Changes
 Articular angle increased because of posterior positioning
mandible
 Mandibular plane angle slightly opened.
 SNA increased
 ANB increased
 Maxillary incisor tipped labially
 Mandibular incisors tipped lingually.

 In a skeletal class III malocclusion with a normal path of closure
from postural rest to habitual occlusion, the treatment with
functional appliance is not always possible.
 The true mandibular prognathism is undoubtedly one of the
most difficult conditions to treat orthodontically.


HARVOLD – WOODSIDE ACTIVAOR
 Harvold (1974) and Wood side (1973)
 Wood side opens the mandible with the construction bite as
much as to 10 – 15 mm beyond postural rest vertical dimension.
 The forces generated by this extreme bite registration (10-15
mm) represent combination of forces generated by swallowing,
biting, activation of the myotatic reflex in the stretched muscles
of mastication and the power delivered through the viscoelastic
properties of stretched muscles, tendon tissue, Skin and
musculature.
 This appliance works using potential energy.

Class II Div I with increased
LAFH (environmental factors)
 Actual adaptation of the maxilla to
the lower dental arch.
 Partially achieved by retroclination
of the maxillary base.
 Differential eruption of teeth
 good vertical control of both
dental arches and only minor
forward tipping of the lower
incisors.

 Harvold has also emphasized the concept of the “Functional
occlusal place” and the role played by its manipulation in the
successful correction of class II malocclusions. This plane
represents the functional table of occlusion in the first
permanent molar, second molar and first premolar areas.

 The level and inclination of the functional occlusal plane is the
result of the neuromuscular, growth and developmental forces
acting on the dentition.
 The correct manipulation of the functional occlusal plane
involves the inhibition of maxillary buccal segment eruption,
which normally follows a downward and forward curvilinear
eruption path.
 At the same time mandibular buccal segment are permitted to
erupt vertically in harmony with the vertical growth of the lower
face.
 Because the mandibular molar erupt roughly at right angles to
the functional plane, change from class II malocclusion to class I
occlusion is facilitated.

Appliance with dislodging springs


Class III malocclusion


HERREN ACTIVATOR
 The principle-complete
opposition to the kinetic
concept of Andersen – Haupl
appliance.
 By overcompensating the
ventral position of the
mandible in the construction
wax bite.
 By seating the appliance
firmly against the maxillary
dental arch by means of
arrowhead clasps similar to
those used in active plates.

Mode of action
 Graber coined the term “myotonic appliance”.
 The mandible is prevented from assuming the natural restposition – thus if the rest position prescribed by activator does
not coincide with natural rest position, the retractive musculature
is stretched.
 In Class II malocclusion, the construction bite of the Herren
activator dislocates the mandible ventrally, parallel to occlusal
plane by a total of 8mm or more. The improvement of post
normal occlusion was directly related to the amount of
mandibular displacement, in taking the construction wax bite.

 When the activator is inserted, the mandible is purposely carried
forward until it is possible to bite completely in to the
positioning splint.
 The mandible is kept from being retracted because the activator
takes the load of these forces and transmits them in an occipital
direction, to the maxillary dental arch.
 Since “action equals reaction” a force of equal magnitude but
opposite direction acts against the mandibular dental arch.

 The force acts continuously only as long as the Herren or L.S.U
activator is in place i.e. 9 – 10 hrs during night.
 The activator holds the retractive musculature of the mandible
passively stretched.


More over, the activator inserted between the teeth and tongue
act as a shield that keeps the tongue away from the free way
space, which enables the eruption of the teeth, provided that the
acrylic occlusal stops of posterior teeth are ground away from
the appliance.

 According to rat studies reported by Petrovic et al, the action of
Herren type of activator comprises a two-stage effect.
 During the time the activator is worn, the protrusive position of
the mandible (caused by construction bite) causes reduced
increase in length of the lateral pterygoid muscle and at the same
time forms a new sensory “engram” for positioning of the
mandible.
 This causes the mandible to function in a more forward position
during the period when the activator is not worn.
 The forward positioning of the mandible by the contraction of
the lateral pterygoid muscle, when the activator is not being used
causes an accelerated growth rate of condylar cartilage.

Specific features
 Twin arrowhead clasp.
 Expansion screws.
 Lingual springs to correct moderate incisal irregularities.
 Extension of the flanges towards the floor of the mouthmandibular anchorage(lower labial bow if needed)
 Horizontal slot in maxillary incisors for comfort.
 No pathologic changes in TMJ.
 Asymmetrical Class II Div I- Expansion screws with asymmetric
cuts in the appliance

Skeletal effect


To correct the class II malocclusion in an expedient, reliable
and economic way.



To retard forward growth of the maxilla.



To reposition the mandible through mandibular growth, either
in a horizontal or in a vertical direction.



To achieve these performances in the transitional as well as in
the early permanent dentition, independent from the pubertal
growth peak in body height( by over compensating)



To provide a high rate of stability of the treatment results after
several years out of retention.

 Herren activator holds the maxillary dental arch preventing the
maxillary forward growth, the mandibular dental arch carried
forward together with its basal arch.
 The treatment results in,
 Increase of SNB angle
 Decrease of ANB angle
 Mandible length increased (distance measured from middle of
the external ear opening & gnathion– from cephalometric head
films)
 Change in position of the mandible, either a more forward or a
more downward direction.

Dental Effect
 Dentoalveolar compensation (distal movement of upper molars,
mesial movement of the lower molars) appeared to be inversely
related to skeletal adaptation.
 The correction of molar relationship occurred to 55% by
skeletal changes.


Class II Div 2 malocclusions
 Herren advocated
expansion screws,lingual
springs for correction of
retruded incisors and
guiding spurs to relieve
minor crowding.


Class III Malocclusion


Retention
• Retention period - (due to over compensation) 15 months after
normal (neutral) dental arch relationships is achieved and overjet
is corrected.
• This normal dental arch relationship is maintained in taking the
construction wax bite for a retention activator. However the
mandible is carried forward by about 2 mm, beyond neutro
occlusion to compensate for the increase in overjet that occurs as
a result of rotation of the mandible around the condylar hinge
axis when a vertical inter occlusal clearance of 4 – 6 mm is
constructed.

Relapse
 If, treatment started too an early age, partial relapse occur after
retention. It is recommend to start treatment, when premolars
have erupted.
 Corrections of Antero-posterior basal discrepancy, resulting
from this therapy, were shown to be stable even 5 years after the
end of retention.


MODIFICATIONS OF ACTIVATOR


BOW ACTIVATOR
 The upper and lower halvesconnected-elastic bow.
 It is thus possible to change
the relationship of the upper
and lower halves of the
appliance.
 With the treatment of class II
division 1 malocclusion,
beginning can be made with a
small forward positioning,
increasing this gradually by a
periodic adjustment as
recommended by Frankel.

 Taatz (1971) ,
 appliances specially suited for treatment of class II division 1
malocclusion in the deciduous dentition.
 Small children will have the appliance in place for longer periods
of time because they sleep more hours.
 Young patients seem to adapt more easily to bringing the
mandible forward gradually than to a sudden forward
positioning.
 Mixed dentition treatment is probably better from both a
growth response and a patient compliance standpoint.

REDUCED ACTIVATOR OR
CYBERNATOR
 Resembles bionator
 customary labial wire of the
activator is used, as well as
most of other simple
appurtenances of this and
other myofunctional
appliances including the
coffin spring.
 Construction bite?
 Advantages?

 Spurs added to prevent the mesial movement of molars during
the shedding of deciduous molars.
 Can be combined with fixed appliance therapy.
 Headgear tubes can be incorporated for extra oral force.


U BOW ACTIVATOR
• maxillary and mandibular
active plates, joined by a
U bow in the region of
the first permanent
molars.
• In addition to acrylic
covering of the lingual
tissue aspects, gingiva
and teeth, plates also
extend over the occlusal
aspects of all teeth.

 The height of the construction bite is that of interocclusal space
or clearance with the mandible in postural rest for the karwetzky
appliance.
 Thus space varies with the malocclusions.


 U-bow :1 long leg ; 1 short leg .The shorter leg is imbedded
in the upper appliance, whereas the longer leg is attached to
lower plate.

Advantages


Combinations of different types of sagittal or transverse
screws, labial wires and springs enhance the basic appliance
action.



U-bow activator combined with fixed appliance when there are
severe rotations or there is need for selective extraction and
uprighting of teeth contiguous to extraction site.



Orthognathic surgery in adults like corticotomies and sub
apical resections, u bow activator has the potential for use.


PROPULSOR ACTIVATOR

 hybrid appliance.
 Advantage?
 No wire configuration are used with propulsor, acrylic
connecting the upper buccal segment to the lower lingual flange
also serves as occlusal support to stabilize the appliance

 As treatment progresses this acrylic is removed progressively to
allow for unhindered eruption of molars and resultant reduction
of the deep overbites, if exists.
 Also if selective eruption is desired to reduce the class II buccal
segment relationship by upward and forward eruption of the
lower teeth while preventing forward eruption of upper teeth by
removing acrylic in the opposing lower molar area leaving them
free.
 The compliance is usually good because of the lightweight
&minimum bulk of the appliance.

CUT OUT (or) PALATE FREE
ACTIVATOR

 Advantage of the Bionator with some of those of the original
Andersen – Haupl appliance.
 Parts?

 Metzelder changes however do have some advantages.
 Appliance is easier to make.


It may carry all the appurtenances described for the activator.

 These include
 The jackscrew for expansion
 Petrik finger spring for moving individual teeth. (upper&lower
canine after extraction).
 Springs for labial tipping of lower incisors.


Proclining springs for Class II Div 2 cases.

Open Bite

Class III


ELASTIC OPEN ACTIVATOR
 The elastic open activator
resemble the Bionator, with
acrylic anteriorly and with
more wires.
 The Bionator though free
movable in the oral cavity, is
carefully stabilized on
posterior occlusal surfaces or
the lower incisors as the
occasion demands.
 completely lacks such
stabilization and thus its
vertical mobility in the mouth
is unimpeded.

Mode of Action
 The appliance will react to most of the tongue
movements and so it must "come to terms" with the
tongue.
 In this manner, a great number of impulses are
transmitted to the teeth, serving as the basis for
transformative changes.


Standard EOA
 bilateral acrylic parts, an
upper and lower labial wire, a
palatal arch and guiding wires
for upper and lower incisors.
 The acrylic parts extend from
the canine posteriorly to the
point just behind the first or
second permanent molar if it
is present.
 The acrylic is quite thin in
order to leave the largest
possible space for the tongue.
Stabilization of acrylic
position is accomplished by
means of contact with the
lingual surfaces of maxillary
and mandibular canines.

 Relieve the crowding
 To relieve the crowding of
maxillary central incisors, half
of maxillary labial wire was
omitted, with the other half
being used to engage the
incisor. On this side, the
guiding wire was used only
for the opposite side.


 Space maintainer
 For example, the second
deciduous molar has been
lost prematurely. Its space is
maintained by an extension
of contiguous acrylic; with
the flat acrylic surface .a
double wire is placed mesial
to first molar and distal to
first deciduous molars.

 Class II division 1
malocclusion
 Construction bite
 With an overjet as large as
10mm, it is usually possible
to get the incisors in to an
edge-to-edge bite.
 No TMJ problems, even after
such extensive forward
positioning of the mandible.

• Class II division 2 malocclusion or Deckbiss

 Class III mal occlusion
 Edge to edge bite of the
incisors or most retruded
mandibular position.
 The maxillary labial wire
carries lip pads similar to
those of Frankel appliance.


 Unilateral cross bite
 Bite with slight over
correction of the midline is
advantageous.
 The acrylic closely follows
the teeth, except in
mandibular part that
approximates the teeth in
cross bite.


Open Bite


Kinetor- Stockfish
 Stockfish- Elastic activatorsemi double plate appliance
with latex tubing between the
upper and lower components
to stimulate function.
 Elastic appliance-isotonic
muscle contractions-less
force magnitude-less
effective.
 Longer wearing timeefficient.


WUNDERER MODIFICATION OF ACTIVATOR
FOR CLASS III MALOCCLUSION
 The appliance is split
horizontally with the upper
and lower portion connected
by a screw that is embedded
in an acrylic extension of the
mandibular portion behind
the maxillary incisors.


 As the screw is opened the maxillary portion moves anteriorly
with a reciprocal posterior thrust acting on the mandibular
dentition. Occlusal surfaces of the posterior teeth are covered
with acrylic to enhance retention.
 The construction bite for class III case is taken in most retruded
or hinge axis position of the mandible with the incisal edges
2mmor 3mm apart.
 In addition to maxillary labial bow a mandibular labial bow used
to guide the mandible distally as they occlude.

ACTIVATOR-HEAD GEAR
COMBINATION


PFEIFFER-GROBETY
 A cervical headgear with a long
outer bow is used.
 The inner bow is inserted into
buccal tubes attached to the
maxillary first molars and the outer
bow is adjusted to about 5° below
the inner bow.
 This produces a predominantly
distal force through the center of
resistance of the molar teeth and a
lesser vertical extrusive force
component .


 The neck strap produces a force of approximately 400 grams,
measured unilaterally.
 The activator used is based on the design and application
described by Harvold and modified for use with a cervical
headgear applied to the maxillary first molars.
 Brachyfacial and mesofacial types responded most favorably to
this combination.
 This combination is contraindicated in dolichofacial type,
because it results in mandibular clockwise rotation
 Duration of wear- 14 continuous hours a day.


 Pfeiffer and Grobety supported combination activator —
cervical headgear therapy., for two reasons:


to extrude maxillary molars, and

 to apply orthopedic traction to the maxilla and an activator to
induce orthopedic mandibular changes, restrain maxillary
growth, and cause selective eruption of teeth.


Drawbacks?


STOCKLI-TEUCHER APPROACH

 The inner face bow is
completely embedded in the
labial side of the maxillary splint,
and the short outer arms are
bent upward depending on the
desired angle to the occlusal
plane.
 Torquing springs, jackscrews,
lip pads Can also be
incorporated.

 Vertical control
 the untrimmed interocclusal acrylic
acts as a bite block.
 the inclination of the outer face bow
precise control over the direction of
force, according to the following
principles:
 A force passing through the center
of resistance produces pure
translation in the direction of the
force.
 A force passing at a distance from
the center of resistance generates a
moment, with a combined effect of
rotation (from the moment) and
translation (from the force).

 Duration of wear
 Active treatment usually takes about 10 months, with the
appliance worn at night and for a few hours during the day (1214 hours total per day).


Stockfish & Hickam
 Stockfish-Kinetor ( elastic activator ) with high pull headgear
attached to the buccal tubes in molar bands.


Hickam- Extraoral force applied to the hooks soldered to the
labial bow of the activator- control of the downward and
backward rotation of the maxilla and have a restrictive effect on
the horizontal and vertical maxillary basal and dentoalveolar
components.

Bass Appliance
 Neville (1987)- maxillary
splint, with an anterior
expansion screw and an
incisor torquing spring .
 Lingual pads for mandibular
growth enhancement are
slotted into the splint, which
also carries detachable side
and labial screens.
 The appliance system offers
considerable flexibility in
design, much as with an
edgewise approach.

Trimming of the activator


Pinciples in Trimming
 The force is intermittent. This allows dynamic and rhythmic
muscle forces to act in such a manner that the appliance acts by
kinetic energy.
 The direction of the desired force is determined by selective
grinding of the acrylic surfaces that contact the teeth.
 The magnitude of force is determined by the amount of acrylic
that contact the teeth.
 The acrylic surface that transmit the force and contact the teeth
are called guide planes
 Evaluation?

VERTICAL CONTROL
 INTRUSION OF
TEETH:
 Incisors:
 Can be achieved by loading
the incisal edges of teeth, the
labial bow should be below
the area of greatest
convexity or on incisal third.
 Molars:
 Performed by loading only
the cusps. The pits and fossas
are cleared to eliminate any
possible incline plane effect

Extrusion of teeth
 Incisors:
 Requires loading the acrylic
above the area of greatest
concavity in the maxilla and
below this area in the
mandible. Although not
effective can be enhanced by
placing the labial bow above
the area of greatest
convexity.
 Indicated in Open bite
problems(finger sucking)


 Molars:
 Requires loading the acrylic
above the area of greatest
convexity in the maxilla and
below this area in the
mandible.
 Indicated in deep bite cases.
 Simultaneous extrusion of
both the upper and lower
buccal segments-no adequate
conttrol.

PROTRUSION OF INCISORS
 Incisors can be
protruded by loading
their lingual surface and
screening lip strain by
passive labial bow.
 Entire lingual surface
loaded
 Incisal third of lingual
surface is loaded.

Retrusion of Incisors

 Acrylic is trimmed from the back of incisor
 Active Labial bow is incorporated

MOVEMENT OF POSTERIORS IN
SAGITAL PLANE
 Distalization:
 the Guide planes are
loaded in the mesio
lingual surfaces.
 Indicated in class II
cases.


 Mesial movement:
 Can be achieved by loading the disto - lingual
surfaces.
 Indicated for the upper arch in class III cases.

Movement in transverse plane
 To achieve transverse
movement the lingual
acrylic surfaces opposite
to the posterior teeth
must be in contact with
teeth.
 More effective expansion
can be achieved using
Jack screws.


Activator Trimming in Class II
malocclusions
 If upper incisors are to be retruded and the labial bow is activeacrylic capping needed to prevent extrusion.
 Lower incisor capping needed to prevent lower incisor
proclination.
 Selective trimming of the acrylic that prevents mesial movement
of the upper buccal segments and enhances mesial movement of
the lower buccal segment- Class II correction.

Activator Trimming in Class III
malocclusions
 The upper incisors are loaded for protrusion and labial bow
passive.
 Lip pads used instead of labial bow to stimulate basal maxillary
development.
 Lower incisors are retruded-acrylic ground lingually ,labial bow
active.
 Upper posterior teeth guided mesially and lower posterior teeth
guided distally- Class III correction.

Vertical dysplasia
 Deep bite cases: The incisors are guided for intrusion and molars
for extrusion .The labial bow active and contacts the incisal third.
 Open Bite cases: The incisor area trimmed for extrusion and the
molar area is intruded. The labial bow active and contacts the
gingival third.


Limitations of Activator Treatment…

 appliance cannot be used by itself to correct crowding.
 The appliance is not used in correction of Class I problems of
crowded teeth caused by disharmony between tooth size and jaw
size
 Although the activator is effective in correction of overbite, it
does not routinely achieve such correction through the intrusion
of incisor teeth, but rather it permits the eruption teeth in the
buccal segments.
 Because the teeth in the buccal segments are permitted to follow
their normal eruption paths and the incisor teeth are not
permitted to erupt; the effect of intrusion is achieved without
actually intruding the incisor teeth.

 It is more likely that successful activator treatment coincides with
normal periods of active mandibular growth
 Excessive LAFH and extreme vertical growth pattern.
 Excessive procumbent lower incisors.
 Nasal stenosis or chronic untreated allergy.
 Non growing individuals.


Thought for the Day..!


Thank you
For more details please visit


Activator and its modifications /certified fixed orthodontic courses /certified fixed orthodontic courses by Indian dental academy

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Activator and its modifications /certified fixed orthodontic courses /certified fixed orthodontic courses by Indian dental academy