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ACTIVATOR AND ITS MODIFICATIONS
INDIAN DENTAL ACADEMY
Leader in continuing dental education www.indiandentalacademy.com
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ACTIVATOR AND ITS MODIFICATIONS…
Catch them Young
Watch them Grow
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History…
Kingsley(1879) – “ jumping the bite ”
Robin 1902- Monobloc.
Viggow Andresen (1908)
Andresen and Haupl (1955)
- Activator.
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Mechanism of Action…
MECHANISM OF THE STRETCH (OR) MYOTATIC RELEX:
How does it work? Monosynaptic? Postural rest position? Isometric contractions?www.indiandentalacademy.com
My View…
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Harvold and Woodside ,Herren ,Selmer-Olsen
viscoelastic properties of soft tissue
Rationale? www.indiandentalacademy.com
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. www.indiandentalacademy.com
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.
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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. www.indiandentalacademy.com
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.
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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.
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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
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EFFECT OF ACTIVATOR TREATMENT
Skeletal ChangesClass 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.
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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.
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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.
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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.www.indiandentalacademy.com
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.
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♫ 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
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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.
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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?
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Construction biteBite is taken by retruding
the jaw. The extent of vertical opening depends on the retrusion possible.
REVERSE ACTIVATOR
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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Appliance with dislodging springs
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Class III malocclusion
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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.www.indiandentalacademy.com
Mode of action
Graber coined the term “myotonic appliance”.
The mandible is prevented from assuming the natural rest-
position – 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.www.indiandentalacademy.com
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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.
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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.
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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. www.indiandentalacademy.com
Specific features
Twin arrowhead clasp.
Expansion screws.
Lingual springs to correct moderate incisal irregularities.
Extension of the flanges towards the floor of the mouth-mandibular 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
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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.
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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.
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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.
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Class II Div 2 malocclusions
Herren advocated expansion screws,lingual springs for correction of retruded incisors and guiding spurs to relieve minor crowding.
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Class III Malocclusion
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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.
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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.
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MODIFICATIONS OF ACTIVATOR
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BOW ACTIVATOR The upper and lower halves-
connected-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.
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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.
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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?www.indiandentalacademy.com
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.
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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.
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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.
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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.
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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.
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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
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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.
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CUT OUT (or) PALATE FREE ACTIVATOR
Advantage of the Bionator with some of those of the original Andersen – Haupl appliance.
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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.
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Open Bite Class III
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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. www.indiandentalacademy.com
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.
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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.www.indiandentalacademy.com
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.
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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.www.indiandentalacademy.com
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.
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• Class II division 2 malocclusion or Deckbiss
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Class III mal occlusion
Construction bite
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.
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Unilateral cross bite Construction 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.
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Open Bite
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Kinetor- Stockfish
Stockfish- Elastic activator- semi 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 time-efficient.
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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.
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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.www.indiandentalacademy.com
ACTIVATOR-HEAD GEAR COMBINATION
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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 .www.indiandentalacademy.com
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.
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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?
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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.
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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).www.indiandentalacademy.com
Duration of wear
Active treatment usually takes about 10 months, with the
appliance worn at night and for a few hours during the day (12-
14 hours total per day).
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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.
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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.
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Trimming of the activator
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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?www.indiandentalacademy.com
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
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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)
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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.
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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.
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Retrusion of Incisors
Acrylic is trimmed from the back of incisor
Active Labial bow is incorporated
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MOVEMENT OF POSTERIORS IN SAGITAL PLANE Distalization: the Guide planes are
loaded in the mesio lingual surfaces.
Indicated in class II cases.
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Mesial movement:
Can be achieved by loading the disto - lingual
surfaces.
Indicated for the upper arch in class III cases.
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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. www.indiandentalacademy.com
Activator Trimming in Class II malocclusions
If upper incisors are to be retruded and the labial bow is active-
acrylic 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.
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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.
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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.
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Limitations of Activator Treatment…www.indiandentalacademy.com
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.www.indiandentalacademy.com
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.
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