Activator /certified fixed orthodontic courses by Indian dental academy

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
www.indiandentalacademy.comwww.indiandentalacademy.com

ACTIVATORACTIVATOR

HISTORYHISTORY
 Kingsley in 1880 introduced the term- jumping the bite forKingsley in 1880 introduced the term- jumping the bite for
patients with mandible retrusion. He inserted a vulcanitepatients with mandible retrusion. He inserted a vulcanite
palatal plate consisting of an anterior incline that guided thepalatal plate consisting of an anterior incline that guided the
mandible in a forward position when the pt closed on it. Thismandible in a forward position when the pt closed on it. This
corrected the sagittal relationship without tipping the lowercorrected the sagittal relationship without tipping the lower
incisors forward.incisors forward.
 Hotz Vorbissplate was a modification of Kingsley plate. HeHotz Vorbissplate was a modification of Kingsley plate. He
used it in case of deep bite retrognathism, when the overbiteused it in case of deep bite retrognathism, when the overbite
was likely to cause a functional retrusion and the lowerwas likely to cause a functional retrusion and the lower
incisors were lingually inclined by the hyperactivity of theincisors were lingually inclined by the hyperactivity of the
mentalis muscle and lower lip.mentalis muscle and lower lip.

 The activator was originally used by Andresen withThe activator was originally used by Andresen with
vertical extensions to contact the lingual surfaces ofvertical extensions to contact the lingual surfaces of
mandibular teeth. He developed a mobile loose-fittingmandibular teeth. He developed a mobile loose-fitting
appliance that transferred functioning muscle stimuliappliance that transferred functioning muscle stimuli
to the jaws, teeth and supporting tissues.to the jaws, teeth and supporting tissues.
 The progenitor of the appliance was a modifiedThe progenitor of the appliance was a modified
Kingsley plate that Andersen used as a retainer overKingsley plate that Andersen used as a retainer over
summer vacation for his daughter after he removedsummer vacation for his daughter after he removed
fixed appliance used to correct distocclusion. Seeingfixed appliance used to correct distocclusion. Seeing
the improvement with this retainer, he called itthe improvement with this retainer, he called it
biomechanical working retainer.biomechanical working retainer.

 Pierre Robin – developed monobloc prior to AndersenPierre Robin – developed monobloc prior to Andersen
appliance.appliance.
 Andersen became associated with Haupl at the university ofAndersen became associated with Haupl at the university of
Oslo. Both termed the appliance as Activator because of itsOslo. Both termed the appliance as Activator because of its
ability to stimulate muscle forces.ability to stimulate muscle forces.
 Haulp concept of individual optimum. The limitation of theHaulp concept of individual optimum. The limitation of the
appliance is that it cannot create a large mandible from a smallappliance is that it cannot create a large mandible from a small
one, but can help pt achieve optimal size consistent withone, but can help pt achieve optimal size consistent with
morphogenetic pattern.morphogenetic pattern.
 The original appliance combined an upper and a lower plate atThe original appliance combined an upper and a lower plate at
the occlusal plane. Only one wire element was used- a labialthe occlusal plane. Only one wire element was used- a labial
arch for the upper ant. teeth. To achieve expansion, thearch for the upper ant. teeth. To achieve expansion, the
appliance was split in the centre and a flexible coffin springappliance was split in the centre and a flexible coffin spring
was incorporated.was incorporated.

DRAWBACK OF ACTIVATORDRAWBACK OF ACTIVATOR
THERAPYTHERAPY
1. Dual bite can be a late consequence of activator1. Dual bite can be a late consequence of activator
treatment with a false indication.treatment with a false indication.
Indicated in retroposition of the condyle in the fossaIndicated in retroposition of the condyle in the fossa
as a result of dominant retrusive activity of theas a result of dominant retrusive activity of the
posterior temporalis, deep masseter and the hyoidposterior temporalis, deep masseter and the hyoid
musculature associated with deep bite.musculature associated with deep bite.
2. Jumping the bite should be performed without2. Jumping the bite should be performed without
proclination of the lower incisors. Failure of activatorproclination of the lower incisors. Failure of activator
therapy occurred as a result of overjet reduction duetherapy occurred as a result of overjet reduction due
to proclination of teeth instead of bodily anteriorto proclination of teeth instead of bodily anterior
positioning of the mandible.positioning of the mandible.

EVOLUTION OF APPLIANCEEVOLUTION OF APPLIANCE
 Eschler – developed modification of the labialEschler – developed modification of the labial
bow that improved intermaxillarybow that improved intermaxillary
effectiveness. One part was active, moving theeffectiveness. One part was active, moving the
teeth, the other was passive, holding the softteeth, the other was passive, holding the soft
tissue of the lower lip away and thustissue of the lower lip away and thus
enhancing the tooth movement desired.enhancing the tooth movement desired.

 The initial appliance was worn at night and hence its bulkThe initial appliance was worn at night and hence its bulk
was not critical. Subsequent modifications made to reducewas not critical. Subsequent modifications made to reduce
the bulk allowed an increase in wearing time. They werethe bulk allowed an increase in wearing time. They were
two types of modifications-two types of modifications-
1.1. Some appliance consist of one rigid acrylic mass for theSome appliance consist of one rigid acrylic mass for the
maxillary and mandibular arches but with reducedmaxillary and mandibular arches but with reduced
volume/bulk.volume/bulk.
a.a. Appliance were reduced in the anterior palatal region- openAppliance were reduced in the anterior palatal region- open
activator. Their goal is to restore exteroceptive contactactivator. Their goal is to restore exteroceptive contact
between the tongue and palate, which is prevented in thebetween the tongue and palate, which is prevented in the
classical activator. Pt prefer it as they are reduced in theclassical activator. Pt prefer it as they are reduced in the
linguoincisal area and do not obstruct the oral cavity.linguoincisal area and do not obstruct the oral cavity.

disadvantages- construction bite cannot be opened too fardisadvantages- construction bite cannot be opened too far
vertically because it impairs the tongue function. The tonguevertically because it impairs the tongue function. The tongue
may thrust into the anterior interincisal gap, creating a posturalmay thrust into the anterior interincisal gap, creating a postural
and functional abnormality.and functional abnormality.
elastic open activator ( Klammt)- lack of support in the cutawayelastic open activator ( Klammt)- lack of support in the cutaway
area of the appliance, especially if guidance of erupting teetharea of the appliance, especially if guidance of erupting teeth
or expansion is necessary.or expansion is necessary.
b. Appliance with reduced alveolar region and with cross palatalb. Appliance with reduced alveolar region and with cross palatal
wires instead of full acrylic plate. They arewires instead of full acrylic plate. They are
supported/anchored dentally. Hence due to their tooth bornesupported/anchored dentally. Hence due to their tooth borne
anchorage their use is limited and management can beanchorage their use is limited and management can be
difficult. The labial bow eliminates abnormal muscle pressuredifficult. The labial bow eliminates abnormal muscle pressure
by extending into the buccal vestibule area.by extending into the buccal vestibule area.

2. Appliance consist of two parts joined with wire bows. The2. Appliance consist of two parts joined with wire bows. The
muscle impulse are reinforced by the wire elementsmuscle impulse are reinforced by the wire elements
incorporated in the design. The flexibility of the applianceincorporated in the design. The flexibility of the appliance
permits mandibular movements in all directions.permits mandibular movements in all directions.
a.a. Schwartz double plateSchwartz double plate
b.b. Stockfish- elastic activatorStockfish- elastic activator
Difference in the mode of action of rigid one piece activatorDifference in the mode of action of rigid one piece activator
(long lasting tonic phase reflex contraction) and flexible two(long lasting tonic phase reflex contraction) and flexible two
piece joined by intermaxillary wiring (transient phase reflexpiece joined by intermaxillary wiring (transient phase reflex
contraction)contraction)

SKELETAL ANDSKELETAL AND
DENTOALVEOLAR EFFECTDENTOALVEOLAR EFFECT

FORCE ANALYSISFORCE ANALYSIS
 When activator activates the muscles, various types of forces areWhen activator activates the muscles, various types of forces are
created-created-
a.a. Static force-Static force- permanent and vary in magnitude and direction. They doand vary in magnitude and direction. They do
not appear simultaneously with the movement of mandible. Eg- forcesnot appear simultaneously with the movement of mandible. Eg- forces
of gravity, posture and elasticity of soft tissue and muscle.of gravity, posture and elasticity of soft tissue and muscle.
a.a. Dynamic force-Dynamic force- interrupted, appear simultaneously with the movementsinterrupted, appear simultaneously with the movements
of the head and body and have a higher magnitude than static force. Eg-of the head and body and have a higher magnitude than static force. Eg-
swallowingswallowing
a.a. Rhythmic force-Rhythmic force- associated with respiration and circulation. They areassociated with respiration and circulation. They are
synchronous with breathing and their amplitude varies with the pulse.synchronous with breathing and their amplitude varies with the pulse.
Imp. In stimulating cellular activity. Mandible transmits rhythmicImp. In stimulating cellular activity. Mandible transmits rhythmic
vibrations to the maxilla. The applied forces are intermittent andvibrations to the maxilla. The applied forces are intermittent and
interrupted. Force application to the teeth are intermittent. Removal ofinterrupted. Force application to the teeth are intermittent. Removal of
activator from mouth interrupts these forces.activator from mouth interrupts these forces.

 Two principles are applied in modern activatorTwo principles are applied in modern activator
therapy-therapy-
force application- muscleforce application- muscle
force elimination- the dentition is shieldedforce elimination- the dentition is shielded
away from normal and abnormal functionalaway from normal and abnormal functional
and tissue pressure by pads, shields and wireand tissue pressure by pads, shields and wire
configuration.configuration.

 Types of forces employed in activator therapy-Types of forces employed in activator therapy-
a.a. Natural force- growth potential, eruption and migration of teeth. These can beNatural force- growth potential, eruption and migration of teeth. These can be
guided, promoted or inhibited by the activator.guided, promoted or inhibited by the activator.
a.a. Artificially functioning forces- muscle contraction and stretching of soft tissuesArtificially functioning forces- muscle contraction and stretching of soft tissues
initiate forces when the mandible is relocated from its postural rest position byinitiate forces when the mandible is relocated from its postural rest position by
the appliance. The activator stimulates and transforms the contractions. Whereasthe appliance. The activator stimulates and transforms the contractions. Whereas
the forces may be muscular in origin, their activation is artificial.the forces may be muscular in origin, their activation is artificial.
sagittal plane- effect on the condylesagittal plane- effect on the condyle
vertical plane- teeth and the alveolar process are loaded with or relieved ofvertical plane- teeth and the alveolar process are loaded with or relieved of
normal forces. If the construction bite is high it will inhibit the growth of maxillanormal forces. If the construction bite is high it will inhibit the growth of maxilla
and influence the inclination of the maxillary base.and influence the inclination of the maxillary base.
transverse plane- midline correctiontransverse plane- midline correction
c. Various active elements (springs, screws) can be built into the activator toc. Various active elements (springs, screws) can be built into the activator to
produce an active biomechanical type of force application.produce an active biomechanical type of force application.

CONSTRUCTION BITECONSTRUCTION BITE
Horizontal H activator- low construction biteHorizontal H activator- low construction bite
with marked forward mandibular positioningwith marked forward mandibular positioning
a.a. Class II functional retrusionClass II functional retrusion
b.b. Class II Div 1 malocclusion with sufficientClass II Div 1 malocclusion with sufficient
overjetoverjet
c.c. Class II Div 1 malocclusion with posteriorClass II Div 1 malocclusion with posterior
positioning of the mandible caused bypositioning of the mandible caused by
growth deficiency but with the likelihood ofgrowth deficiency but with the likelihood of
a future horizontal growth patterna future horizontal growth pattern

 Vertical V activator- high construction biteVertical V activator- high construction bite
with slightly anterior mandibular positioningwith slightly anterior mandibular positioning
a. Class II Div 1 malocclusion with verticala. Class II Div 1 malocclusion with vertical
growth directiongrowth direction

FABRICATION OF ACTIVATORFABRICATION OF ACTIVATOR

TRIMMING OF ACTIVATORTRIMMING OF ACTIVATOR
 PRINCIPLES-PRINCIPLES-
The movement andThe movement and eruption of selected teeth
can be achieved by grinding away areas of
acrylic that contact the tooth surface.
Carefully planned grinding and trimming of the
activator in the tooth contact area improves its
effectiveness in the dentoalveolar region by
stimulating or restricting selective eruption
and movement of anterior and posterior teeth.

 The principles of force application in the trimming processThe principles of force application in the trimming process
are determined by the typa, direction and magnitude of forceare determined by the typa, direction and magnitude of force
created by the loosely fitting appliancecreated by the loosely fitting appliance
a. Intermittent force- isotonic and isometric muscle contractionsa. Intermittent force- isotonic and isometric muscle contractions
enabling the appliance to work by utilizing kinetic energy.enabling the appliance to work by utilizing kinetic energy.
b. The direction of the desired force is determined by selectiveb. The direction of the desired force is determined by selective
grinding of the acrylic surface that contact the u & l teeth.grinding of the acrylic surface that contact the u & l teeth.
After proper grinding the desired force acts on predeterminedAfter proper grinding the desired force acts on predetermined
areas of the teeth and applies pressure in the direction ofareas of the teeth and applies pressure in the direction of
needed tooth movement.needed tooth movement.
..

c. The magnitude of force can be estimated by determining thec. The magnitude of force can be estimated by determining the
amount of acrylic contact with the tooth surface. If the force isamount of acrylic contact with the tooth surface. If the force is
delivered to smaller portion of tooth surface, it is greater thandelivered to smaller portion of tooth surface, it is greater than
if broader contact occurs between the acrylic and broaderif broader contact occurs between the acrylic and broader
tooth surface. Acrylic surface that transmit the desired forcetooth surface. Acrylic surface that transmit the desired force
and contact the teeth are called guide planes.and contact the teeth are called guide planes.
d. Approximate trimming can be done on the plaster cast but thed. Approximate trimming can be done on the plaster cast but the
final trimming is done in the mouth. Any undercut acrylicfinal trimming is done in the mouth. Any undercut acrylic
surface that might interfere with planned tooth guidance mustsurface that might interfere with planned tooth guidance must
be removed. Need for trimming can be assessed by-be removed. Need for trimming can be assessed by-
explorerexplorer
observing the shadows created on the acrylic by the undercutobserving the shadows created on the acrylic by the undercut

FOR VERTICAL CONTROLFOR VERTICAL CONTROL
 IntrusionIntrusion
 Prevention of teeth from eruptionPrevention of teeth from eruption
 Teeth are free to erupt and are stimulated to doTeeth are free to erupt and are stimulated to do
so by acrylic planesso by acrylic planes

INTRUSION OF TEETHINTRUSION OF TEETH
 Incisors-Incisors-
Performed by loading the incisor edgesPerformed by loading the incisor edges
Indicated in deep overbite caseIndicated in deep overbite case

 Molars-Molars-
Performed by loading the cusps of teethPerformed by loading the cusps of teeth
Acrylic detail is ground away from the fissuresAcrylic detail is ground away from the fissures
and fossas to eliminate any possible inclinedand fossas to eliminate any possible inclined
plane stimulation to molar movementplane stimulation to molar movement
Indicated in open bite casesIndicated in open bite cases

EXTRUSION OF TEETHEXTRUSION OF TEETH
 Incisor-Incisor-
Loading the lingual surfaces above the area ofLoading the lingual surfaces above the area of
greatest concavity in the maxilla and belowgreatest concavity in the maxilla and below
this area in the mandiblethis area in the mandible
Enhanced by placing the labial bow above theEnhanced by placing the labial bow above the
area of greatest convexityarea of greatest convexity
Indicated for open bite casesIndicated for open bite cases

 Molars-Molars-
Loading the lingual surfaces of teeth above theLoading the lingual surfaces of teeth above the
area of greatest convexity in the maxilla orarea of greatest convexity in the maxilla or
below this area in the mandiblebelow this area in the mandible
Indicated in deep bite casesIndicated in deep bite cases

SELECTIVE TRIMMING OF THESELECTIVE TRIMMING OF THE
ACTIVATORACTIVATOR
 By this only the u & l molars are extrudedBy this only the u & l molars are extruded
 Path of eruption of molars should bePath of eruption of molars should be
consideredconsidered
 In case of Class II malocclusion- eruption ofIn case of Class II malocclusion- eruption of
maxillary molar is inhibited while that of themaxillary molar is inhibited while that of the
mandibular molars is stimulatedmandibular molars is stimulated
 In case of Class III malocclusion- eruption ofIn case of Class III malocclusion- eruption of
mandibular molar is inhibited while that of themandibular molar is inhibited while that of the
maxillary molars is stimulatedmaxillary molars is stimulated

FOR SAGITTAL CONTROLFOR SAGITTAL CONTROL
 By this protrusion or retrusion of incisors andBy this protrusion or retrusion of incisors and
change in molar sagittal relationship mesiallychange in molar sagittal relationship mesially
or distally can be achieved.or distally can be achieved.

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Activator /certified fixed orthodontic courses by Indian dental academy

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