Copy of activator /orthodontic courses by Indian dental academy

Modifications ofModifications of
ActivatorActivator
INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMY
Leader in continuing DentalLeader in continuing Dental
EducationEducation
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTSCONTENTS
 IntroductionIntroduction
 Modifications used in correction of Class II division1Modifications used in correction of Class II division1
 Modifications used in correction of Class II division 2Modifications used in correction of Class II division 2
 Modifications used in correction of Class IIIModifications used in correction of Class III
 Eschler’s Modification (1952)Eschler’s Modification (1952)
 Herren's activator (1953)Herren's activator (1953)
 Herren's shaye activator – LSU activator (1953)Herren's shaye activator – LSU activator (1953)
 Elastic open activator of Klammt (1955)Elastic open activator of Klammt (1955)
 The bow activator of Schwarz (1956)The bow activator of Schwarz (1956)
 The Karwetsky appliance (1964)The Karwetsky appliance (1964)
 The propulsor(1968)The propulsor(1968)
 Wunderer’s modification (1971)Wunderer’s modification (1971)
 Reduced activator of Cybernator of Schmuth (1973)Reduced activator of Cybernator of Schmuth (1973)
 Harvold Woodside Activator (1963)Harvold Woodside Activator (1963)
 The cutout (or) palate free activatorThe cutout (or) palate free activator
 Magnetic activator device 1993Magnetic activator device 1993
 Stockli & TeuscherStockli & Teuscher
 Stockfish’s KinetorStockfish’s Kinetor
 Hickham And Shaye CombinationHickham And Shaye Combination
 BionatorBionator

IntroductionIntroduction
 Fox (1803) advocated application of extra oralFox (1803) advocated application of extra oral
force to control the growth of maxilla.force to control the growth of maxilla.
 KINGSLEY introduced "Jumping of the bite": inKINGSLEY introduced "Jumping of the bite": in
1879 to correct sagittal relationship between1879 to correct sagittal relationship between
Upper and lower jaws.Upper and lower jaws.
 HOTZ modified the kingsley's plate into aHOTZ modified the kingsley's plate into a
vorbissplate (used it for deep bite andvorbissplate (used it for deep bite and
retrognathism).retrognathism).
 From Kingsley's concept, VIGGO ANDRESENFrom Kingsley's concept, VIGGO ANDRESEN
1908 developed a loose fitting appliance on his1908 developed a loose fitting appliance on his
daughter as a retainer during summer vacationsdaughter as a retainer during summer vacations
which gave remarkable results. He called itwhich gave remarkable results. He called it
BIOMECHANICAL RETAINER.BIOMECHANICAL RETAINER.

 Modifications can be broadly categorized intoModifications can be broadly categorized into
2 types2 types
1. Appliances with ONE RIGID ACRYLIC1. Appliances with ONE RIGID ACRYLIC
MASS for maxillary and mandible arches butMASS for maxillary and mandible arches but
with reduced volume or bulk.with reduced volume or bulk.
2. Appliance consisting of2. Appliance consisting of 2 parts2 parts joined byjoined by
wire bows. Muscle impulse are reinforced bywire bows. Muscle impulse are reinforced by
wire elements in the design.wire elements in the design.

 Experimental simulation of activator therapyExperimental simulation of activator therapy
has been found to induce increased cellularhas been found to induce increased cellular
activity in the mandibular condyle.activity in the mandibular condyle.
 Harvold however, found no evidence ofHarvold however, found no evidence of
increased mandibular growth in patientsincreased mandibular growth in patients
treated with activator therapy, and hetreated with activator therapy, and he
convincingly described the selectiveconvincingly described the selective
influence of the activator on occlusalinfluence of the activator on occlusal
development.development.

CORRECTION OF CLASS IICORRECTION OF CLASS II
DIVISION 1DIVISION 1
MALOCCLUSIONSMALOCCLUSIONS

FabricationFabrication
Pre- treatment considerationsPre- treatment considerations
 The forward movement 0f mandible should beThe forward movement 0f mandible should be
checked to see that it is not blocked by the occlusalchecked to see that it is not blocked by the occlusal
interference that make the correction of theinterference that make the correction of the
distoclusion impossible.distoclusion impossible.
 Interference may be caused- by a single toothInterference may be caused- by a single tooth
 A quite common cause for interference is the buccalA quite common cause for interference is the buccal
cross bite of an upper premolar.cross bite of an upper premolar. The buccal crossThe buccal cross
bitebite mustmust be corrected firstbe corrected first withwith an active plate.an active plate.

Construction BiteConstruction Bite
 The Extent of Maximum Forward Movement of theThe Extent of Maximum Forward Movement of the
MandibleMandible
 The optimal forward movement mandible for theThe optimal forward movement mandible for the
construction bite is usually half the individual'sconstruction bite is usually half the individual's
maximum according to Martin Schwarz (1956)maximum according to Martin Schwarz (1956)
(1) If the protrusive construction bite is more than half(1) If the protrusive construction bite is more than half
the maximum movement, it becomes morethe maximum movement, it becomes more
uncomfortable for the patient.uncomfortable for the patient.
(2) The distance of 5mm is approximately the same as(2) The distance of 5mm is approximately the same as
that between the points of the buccal cusps of firstthat between the points of the buccal cusps of first
molars. This is the amount of distance necessary tomolars. This is the amount of distance necessary to
change a Class II malocclusion into a Class Ichange a Class II malocclusion into a Class I
occlusion.occlusion.

3) It is claimed that one of the best positions lining3) It is claimed that one of the best positions lining
the desired histological transformation of the TMJthe desired histological transformation of the TMJ
from a Class II malocclusion to a Class Ifrom a Class II malocclusion to a Class I
occlusion is approximately half the distance thatocclusion is approximately half the distance that
the condyle can movethe condyle can move forward along the anteriorforward along the anterior
wall of the fossa to the articular tubercle.wall of the fossa to the articular tubercle.
 The Extent of the Individual's Occlusal ClearanceThe Extent of the Individual's Occlusal Clearance
in the Resting Positionin the Resting Position
 The Establishment of the True Midlines of theThe Establishment of the True Midlines of the
Upper and Lower JawsUpper and Lower Jaws

Freeing the way for eruption inFreeing the way for eruption in
deep bite casesdeep bite cases

Periodic control of activators proper fitPeriodic control of activators proper fit

Arch expansionArch expansion

Sagittal section through anterior regionSagittal section through anterior region

CORRECTION OF CLASS II,CORRECTION OF CLASS II,
DIVISION 2 MALOCCLUSIONDIVISION 2 MALOCCLUSION

CORRECTION OF OPEN BITECORRECTION OF OPEN BITE
 The activator is not indicated for the treatment of skeletalThe activator is not indicated for the treatment of skeletal
open bite.open bite.
 It may be used for treatment of open bites caused byIt may be used for treatment of open bites caused by
tongue- thrust and finger sucking.tongue- thrust and finger sucking.
 It is constructed so that eruption of the posterior teeth isIt is constructed so that eruption of the posterior teeth is
prevented, whereas elongation of the anterior teeth isprevented, whereas elongation of the anterior teeth is
encouraged.encouraged.
 The acrylic is not ground away from the occlusalThe acrylic is not ground away from the occlusal
surfaces of the posterior teeth, but the anterior teeth aresurfaces of the posterior teeth, but the anterior teeth are
allowed to erupt freely.allowed to erupt freely.
 Besides correcting the vertical development, theBesides correcting the vertical development, the
activator works as a habit appliance by intercepting theactivator works as a habit appliance by intercepting the
tongue-lip contact.tongue-lip contact.
 The weakness of the appliance is that it is limited mainlyThe weakness of the appliance is that it is limited mainly
to nocturnal use.to nocturnal use.

CORRECTION OF CROSSCORRECTION OF CROSS
BITEBITE

CORRECTION OF CLASS IIICORRECTION OF CLASS III
MALOCCLUSIONMALOCCLUSION

Wunderer’s modification(1971)Wunderer’s modification(1971)

Jackscrew designed by WeiseJackscrew designed by Weise
(1969)(1969)11

Eschler’s Modifiaction (1952)Eschler’s Modifiaction (1952)22

L.S.U Activator (1953)L.S.U Activator (1953) 55
 Louisiana State University modificationLouisiana State University modification
 By R. ShayeBy R. Shaye

HERREN’S DENTOFACIALHERREN’S DENTOFACIAL
ORTHOPEDICS (1953)ORTHOPEDICS (1953)11
 By Paul Herren, a young graduate of theBy Paul Herren, a young graduate of the
University of Zurich Dental SchoolUniversity of Zurich Dental School
 He modified the activator in two ways-He modified the activator in two ways-
1.1. By overcompensating the verticalBy overcompensating the vertical
positioning of the mandible in thepositioning of the mandible in the
construction wax biteconstruction wax bite
2.2. By seating the appliance firmly againstBy seating the appliance firmly against
the maxillary arch by means of arowheadthe maxillary arch by means of arowhead
clasps similar to those used in activeclasps similar to those used in active
plates.plates.

The Overcompensating ConstructionThe Overcompensating Construction
wax bite in Class II malocclusionswax bite in Class II malocclusions
 Since the correct posture of the mandibleSince the correct posture of the mandible
during sleep is essential for the success ofduring sleep is essential for the success of
activator therapy, the following rules areactivator therapy, the following rules are
observed while taking a construction bite onobserved while taking a construction bite on
a patient.a patient.
1. Positioning the mandible in an1. Positioning the mandible in an
anteroposterior direction dominates over theanteroposterior direction dominates over the
vertical direction.vertical direction.

2. The distal molar relationship is not only2. The distal molar relationship is not only
compensated but alsocompensated but also
overcompensated.overcompensated.

3. Vertical positioning: In a deep vertical3. Vertical positioning: In a deep vertical
overbite, the incisal edges are kept 2 mmoverbite, the incisal edges are kept 2 mm
to 4 mm apart.to 4 mm apart.
Deep Bite

Open BiteOpen Bite

4. Preservation of midline4. Preservation of midline

Features of the applianceFeatures of the appliance

Activator Active Plate

Need for moderate expansionNeed for moderate expansion

Cross section through the molarCross section through the molar
region Of the 0ral cavityregion Of the 0ral cavity

RetentionRetention
 15 months after the achievement of dental15 months after the achievement of dental
arch relationship.arch relationship.

MODUS OPERANDI OF THEMODUS OPERANDI OF THE
HERREN ACTIVATORHERREN ACTIVATOR
> 8 mm
Study by Graf – 100 g of force every mm of mandibular forward shift.www.indiandentalacademy.comwww.indiandentalacademy.com

H- activatorH- activator
 Low vertical openingLow vertical opening
More horizontal registrationMore horizontal registration
Low construction bite with markedly forwardLow construction bite with markedly forward
mandibular positioning.mandibular positioning.
General rule for construction bite:General rule for construction bite:
SagittalSagittal
VerticalVertical

IndicationsIndications
Class II div 1 malocclusion with sufficientClass II div 1 malocclusion with sufficient
overjet.overjet.
Class II caused by mandibular overclosureClass II caused by mandibular overclosure
that results in functional retrusion.that results in functional retrusion.
Class II div 1 with posterior positioning ofClass II div 1 with posterior positioning of
the mandible , caused by growththe mandible , caused by growth
deficiency but future horizontal growthdeficiency but future horizontal growth
expected.expected.

HARVOLD WOODSIDEHARVOLD WOODSIDE
ACTIVATOR (1963)ACTIVATOR (1963)
 Viscoelastic properties of muscle & the stretchingViscoelastic properties of muscle & the stretching
of soft tissues are decisive factors for activatorof soft tissues are decisive factors for activator
action.action.
 Thus the forces responsible for moving the teeth inThus the forces responsible for moving the teeth in
activator therapy are not due to muscle functionactivator therapy are not due to muscle function
per se but to the stretching of soft tissues.per se but to the stretching of soft tissues.
 Construction bite as much as 10-15 mm beyondConstruction bite as much as 10-15 mm beyond
postural rest position.postural rest position.
 No myotatic reflex but build up of potential energy.No myotatic reflex but build up of potential energy.

Myotatic reflexMyotatic reflex

Clasp knife reflexClasp knife reflex

 Maximal mandibular protrusion minus 3mmMaximal mandibular protrusion minus 3mm
 Vertical bite 8-10mm > than inter-occlusal spaceVertical bite 8-10mm > than inter-occlusal space
i.e. average of 12-15mmi.e. average of 12-15mm
 According to Harvold his “ Functional occlusalAccording to Harvold his “ Functional occlusal
plane ” is the result of neuromuscular forces,plane ” is the result of neuromuscular forces,
growth and functional adaptation duringgrowth and functional adaptation during
development of dentition arresting the growth ofdevelopment of dentition arresting the growth of
the maxillary posterior teeth.the maxillary posterior teeth.

V activatorV activator
 ANTERIOR POSITION: LESS (3 TO 5MMANTERIOR POSITION: LESS (3 TO 5MM
AHEAD OF HABITUAL OCCLUSION)AHEAD OF HABITUAL OCCLUSION)
 VERTICAL : MAXIMUM OF 4MM FROMVERTICAL : MAXIMUM OF 4MM FROM
POSTURAL REST VERTICALPOSTURAL REST VERTICAL
DIMENSION.DIMENSION.

 CLASS II DIV 1 CASES WITH VERTICALCLASS II DIV 1 CASES WITH VERTICAL
GROWTH PATTERN.GROWTH PATTERN.
This case can not be improved significantlyThis case can not be improved significantly
sagittally by anterior positioning of mandible.sagittally by anterior positioning of mandible.
Goal:Goal:
Minimal forward positioning of mandible.Minimal forward positioning of mandible.
Actual adaptation of maxilla to lower arch.Actual adaptation of maxilla to lower arch.
Dentoalveolar compensation.Dentoalveolar compensation.

 At the same time, theAt the same time, the
posterior mandibularposterior mandibular
teeth should eruptteeth should erupt
vertically togethervertically together
with vertical growth ofwith vertical growth of
the lower half of thethe lower half of the
face.face.
 As lower molars eruptAs lower molars erupt
at right angles to theat right angles to the
plane, disto-occlusionplane, disto-occlusion
is converted tois converted to
neutro-occlusion.neutro-occlusion.
 Hence the highHence the high
vertical working bite.vertical working bite.
49www.indiandentalacademy.comwww.indiandentalacademy.com

The Bow ActivatorThe Bow Activator
 By A. M. Schwarz (1956)By A. M. Schwarz (1956)

Reduced Activator or Cybernator ofReduced Activator or Cybernator of
Schmuth (1973)Schmuth (1973)

 SCHMUTH(1994);WITT(1981);WITT &SCHMUTH(1994);WITT(1981);WITT &
KOMPOSCH(1979)KOMPOSCH(1979)
CONSTRUCTION BITE THAT DISPLACECONSTRUCTION BITE THAT DISPLACE
MANDIBLE BEYOND 4TO 6MM FROMMANDIBLE BEYOND 4TO 6MM FROM
HABITUAL OCCLUSIONHABITUAL OCCLUSION  LONG PERIODS OFLONG PERIODS OF
CONTINOUS PRESSURE ON TEETHCONTINOUS PRESSURE ON TEETH

The Karwetzky ModificationThe Karwetzky Modification
 (1964,1970,1974)(1964,1970,1974)

 The space varies with the malocclusion treated and theThe space varies with the malocclusion treated and the
depth of the bite in the original malrelationship of the upperdepth of the bite in the original malrelationship of the upper
and lower arches.and lower arches.
 In open bite problems, the construction bite slightlyIn open bite problems, the construction bite slightly
exceeds the resting position.exceeds the resting position.
 For Class II, Division 1 malocclusions, the horizontalFor Class II, Division 1 malocclusions, the horizontal
forward positioning is only part of the distance required toforward positioning is only part of the distance required to
establish a normal interdigitation, usually not more thanestablish a normal interdigitation, usually not more than
half of the anteroposterior correction required.half of the anteroposterior correction required.
 A similar construction bite is made for Class II, Division 2A similar construction bite is made for Class II, Division 2
malocclusions.malocclusions.
 In Class III, mandibular prognathism cases, theIn Class III, mandibular prognathism cases, the
construction bite is taken in the most posterior positioningconstruction bite is taken in the most posterior positioning
of the mandible possible in postural rest.of the mandible possible in postural rest.

Types of karwetzky activatorTypes of karwetzky activator
 Depending on the placement of the endsDepending on the placement of the ends
of the U bows, three types of theof the U bows, three types of the
Karwetzky activator may be created-eachKarwetzky activator may be created-each
for a different treatment purposefor a different treatment purpose
 Type I for the treatment of Class II,Type I for the treatment of Class II,
Division 1 and Division 2 malocclusionsDivision 1 and Division 2 malocclusions

Type IType I Anterior upper short leg
Posterior lower Long leg

Type IIType II Posterior upper short leg
Anterior lower Long leg

Type IIIType III

The Propulsor (1968)The Propulsor (1968)
 Conceived by Muhlemann and refined byConceived by Muhlemann and refined by
HotzHotz

CUT- OUT OR PALATE-FREECUT- OUT OR PALATE-FREE
ACTIVATORACTIVATOR
 By Metzelder (1968)By Metzelder (1968)

Appliance for the treatment of classAppliance for the treatment of class
II div 1 malocclusionII div 1 malocclusion
 The construction bite for the appliance isThe construction bite for the appliance is
taken, if possible, in an edge to edge incisaltaken, if possible, in an edge to edge incisal
relationship.relationship.
 Stabilization is provided by carrying theStabilization is provided by carrying the
acrylic over the occlusal surfaces of some theacrylic over the occlusal surfaces of some the
buccal teeth, or by a small rim of acrylic thatbuccal teeth, or by a small rim of acrylic that
forms a little groove for the mandibular incisalforms a little groove for the mandibular incisal
margins.margins.

Appliance for the treatment of classAppliance for the treatment of class
II div 2 malocclusionII div 2 malocclusion

Appliance for open bite treatmentAppliance for open bite treatment

The construction used for theThe construction used for the
treatment of Class III problemstreatment of Class III problems

Elastic Open ActivatorElastic Open Activator
 By G. Klammt of Gorlitz, East GermanyBy G. Klammt of Gorlitz, East Germany
(1962)(1962)

Standard type of EOA activator withStandard type of EOA activator with
flat acrylic acrylic partsflat acrylic acrylic parts

Standard type of EOA activator withStandard type of EOA activator with
contiguous acrylic partscontiguous acrylic parts

Mode of Action of the EOAMode of Action of the EOA

Treatment of Class II div 1Treatment of Class II div 1
malocclusionmalocclusion

Treatment of Class II div 2Treatment of Class II div 2
malocclusionmalocclusion

Treatment of Class III malocclusionsTreatment of Class III malocclusions
and anterior cross biteand anterior cross bite

EOA for treatment of open biteEOA for treatment of open bite

TWO PARTS
UPPER AND
LOWER JOINED
BY WIRE BOWS
MUSCLE
IMPULSES
REINFORCED BY
WIRE ELEMENTS
FLEXIBILITY:
MANDIBULAR
MOVEMENTS IN
ALL DIRECTIONS

Magnetic activator device (MAD)Magnetic activator device (MAD)33
(1993)(1993)
 A magnetically active, two-piece (upper and lower),A magnetically active, two-piece (upper and lower),
functional orthopedic appliance has beenfunctional orthopedic appliance has been
developed, magnetic activator device (MAD) fordeveloped, magnetic activator device (MAD) for
the correction of Class II malocclusions.the correction of Class II malocclusions.
 The magnetic forces are used to give freedom ofThe magnetic forces are used to give freedom of
mandibular movement and to allow for continuousmandibular movement and to allow for continuous
functioning of the orofacial muscles when thefunctioning of the orofacial muscles when the
appliance is worn.appliance is worn.
 Samarium cobalt (Sm2Co17) magnets areSamarium cobalt (Sm2Co17) magnets are
incorporated on the buccal aspects of the upperincorporated on the buccal aspects of the upper
and lower appliances.and lower appliances.

 Magnetic forces ranging from 150 to 600Magnetic forces ranging from 150 to 600
gm per side have been used on patients,gm per side have been used on patients,
and it seems that the skeletal versusand it seems that the skeletal versus
dental response depends on the intensitydental response depends on the intensity
of the magnetic force usedof the magnetic force used
 A force of 300 gm, when the magnets areA force of 300 gm, when the magnets are
in contact, on each side has been found toin contact, on each side has been found to
be an appropriate value in patients age 7be an appropriate value in patients age 7
to 12 years.to 12 years.

 The use of this less bulky design rather thanThe use of this less bulky design rather than
a traditional orthopedic appliance, along witha traditional orthopedic appliance, along with
the freedom of function it permits, hasthe freedom of function it permits, has
enabled patients to wear the applianceenabled patients to wear the appliance
nearly 24 hours in most cases.nearly 24 hours in most cases.
 The aim is to retain the positive factors ofThe aim is to retain the positive factors of
traditional functional treatment and add to ittraditional functional treatment and add to it
freedom of mandibular function in everyfreedom of mandibular function in every
possible muscle activity, allowing full-timepossible muscle activity, allowing full-time
wear, except for meals and oral hygiene.wear, except for meals and oral hygiene.www.indiandentalacademy.comwww.indiandentalacademy.com

 Aluminum-nickel-cobalt and platinum-cobaltAluminum-nickel-cobalt and platinum-cobalt
(AlNiCo) alloys were the first magnets used in dental(AlNiCo) alloys were the first magnets used in dental
applications.applications.
 These magnets had their limitations, particularly inThese magnets had their limitations, particularly in
relation to their size, cost and risk ofrelation to their size, cost and risk of
demagnetization.demagnetization.
 The introduction of samarium-cobalt magnets byThe introduction of samarium-cobalt magnets by
Becker, who used an alloy of cobalt and a rare earthBecker, who used an alloy of cobalt and a rare earth
metal samarium (SmCo), has helped to overcomemetal samarium (SmCo), has helped to overcome
these limitations.these limitations.
 When fully magnetized, a samarium-cobalt magnetWhen fully magnetized, a samarium-cobalt magnet
has a ten-fold stronger magnetic field, and itshas a ten-fold stronger magnetic field, and its
resistance to demagnetization is 20 to 50 timesresistance to demagnetization is 20 to 50 times
superior to the AlNiCo type of magnets.superior to the AlNiCo type of magnets.

 Another type of magnet is the neodymium-iron-Another type of magnet is the neodymium-iron-
boron (Nd2Fe14B) group, which have a higherboron (Nd2Fe14B) group, which have a higher
energy product than Sm2Co17 magnets, butenergy product than Sm2Co17 magnets, but
have less resistance to demagnetization and arehave less resistance to demagnetization and are
more prone to corrosion.more prone to corrosion.
 Vardimon and Muller found a 240-fold greaterVardimon and Muller found a 240-fold greater
susceptibility to corrosion of uncoated rare earthsusceptibility to corrosion of uncoated rare earth
magnets made of neodymium than withmagnets made of neodymium than with
samarium alloys.samarium alloys.

 Each appliance has two retention clasps that hookEach appliance has two retention clasps that hook
over buttons bonded on the buccal surface of all fourover buttons bonded on the buccal surface of all four
first permanent molars. The acrylic part of eachfirst permanent molars. The acrylic part of each
appliance covers the occlusal surface of the lateralappliance covers the occlusal surface of the lateral
segments.segments.

Activator Headgear therapyActivator Headgear therapy
 Pfeiffer and Grobety (1982) have previouslyPfeiffer and Grobety (1982) have previously
described combination activator — cervicaldescribed combination activator — cervical
headgear therapy.headgear therapy.
 They preferred to use cervical headgear, whereThey preferred to use cervical headgear, where
necessary, for two reasons: (1) to extrudenecessary, for two reasons: (1) to extrude
maxillary molars, and (2) to apply orthopedicmaxillary molars, and (2) to apply orthopedic
traction to the maxilla and an activator to inducetraction to the maxilla and an activator to induce
orthopedic mandibular changes, restrainorthopedic mandibular changes, restrain
maxillary growth, and cause selective eruption ofmaxillary growth, and cause selective eruption of
teeth.teeth.

 Treatment with combined headgear -Treatment with combined headgear -
activator appliances is indicated foractivator appliances is indicated for
adolescent patients with malocclusions ofadolescent patients with malocclusions of
the Class II, Division 1 type.the Class II, Division 1 type.
 Maxillary prognathism, mandibularMaxillary prognathism, mandibular
retrognathism, and decreased or increasedretrognathism, and decreased or increased
facial height are treated differently byfacial height are treated differently by
varying the design and application of thevarying the design and application of the
appliances.appliances.

 A cervical headgear with a long outer bow is used.A cervical headgear with a long outer bow is used.
 The inner bow is inserted into buccal tubesThe inner bow is inserted into buccal tubes
attached to the maxillary first molars and the outerattached to the maxillary first molars and the outer
bow is adjusted to about 5° below the inner bow.bow is adjusted to about 5° below the inner bow.
 This produces a predominantly distal force throughThis produces a predominantly distal force through
the center of resistance of the molar teeth and athe center of resistance of the molar teeth and a
lesser vertical extrusive force component.lesser vertical extrusive force component.
 During treatment, once a Class I molar occlusionDuring treatment, once a Class I molar occlusion
has been established, the outer bow is raisedhas been established, the outer bow is raised
above the inner bow if uprighting of the molars isabove the inner bow if uprighting of the molars is
indicated.indicated.
 The inner bow is expanded about 5 mm andThe inner bow is expanded about 5 mm and
activated to produce a distobuccal maxillary molaractivated to produce a distobuccal maxillary molar
rotation.rotation.

 The neck strap produces a force ofThe neck strap produces a force of
approximately 400 grams, measured unilaterally.approximately 400 grams, measured unilaterally.
 The activator used is based on the design andThe activator used is based on the design and
application described by Harvold.application described by Harvold.
 It is modified for use with a cervical headgearIt is modified for use with a cervical headgear
applied to the maxillary first molars.applied to the maxillary first molars.
 Patients are instructed to wear the appliancesPatients are instructed to wear the appliances
simultaneously for 14 continuous hours a day.simultaneously for 14 continuous hours a day.
Patients are seen about once every 6 weeks, atPatients are seen about once every 6 weeks, at
which time the necessary adjustments are madewhich time the necessary adjustments are made

• Tooth-borne appliance that attempts to reduce
undesirable dental changes with the addition of high
pull headgear.
• Vertical anterior torquing springs to reduce lingual
tipping of maxillary incisors.
• Headgear will restrict the horizontal growth of the
maxilla
• The acrylic prohibits posterior maxillary eruption
and allow mandibular eruption
The Stockli-type Activator

Stockfish ApproachStockfish Approach
 Extraoral force to maxillary first molarExtraoral force to maxillary first molar
bands in conjunction with his kinetor.bands in conjunction with his kinetor.
 Hickham and Shaye combinationHickham and Shaye combination
Activator + EO force approach for correctionActivator + EO force approach for correction
of sagittal problemsof sagittal problems

ReferencesReferences
1.1. T.M.Graber, Thomas Rakosi, A.G.Petrovic;T.M.Graber, Thomas Rakosi, A.G.Petrovic;
Dentofacial orthopedics with functional appliances:Dentofacial orthopedics with functional appliances:
2nd Edition, Mosby Co. 1997; Page no 161-1942nd Edition, Mosby Co. 1997; Page no 161-194
2.2. T.M.Graber,Bedrich Neumann; removableT.M.Graber,Bedrich Neumann; removable
orthodontic appliances : 2nd edition W.B.Saundersorthodontic appliances : 2nd edition W.B.Saunders
Co. ; Page no 198- 310Co. ; Page no 198- 310
3.3. Darendeliler and Joho MAD II AJO-DO VolumeDarendeliler and Joho MAD II AJO-DO Volume
1993 Mar (223 - 239)1993 Mar (223 - 239)
4.4. Levin Activator headgear therapy AJO-DO VolumeLevin Activator headgear therapy AJO-DO Volume
1985 Feb (91 - 109)1985 Feb (91 - 109)

5. Interviews Dr. Robert Shaye on Functional5. Interviews Dr. Robert Shaye on Functional
Appliances 1983 MayAppliances 1983 May 330 - 342 JCO.330 - 342 JCO.
6. DR. WILLIAM GROSSMAN, DR. JAMES P.6. DR. WILLIAM GROSSMAN, DR. JAMES P.
MOSS Removable Appliance Therapy 1968MOSS Removable Appliance Therapy 1968
JCO Jan 28 - 36JCO Jan 28 - 36

Copy of activator /orthodontic courses by Indian dental academy

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