Modifications of Activator

Modifications ofModifications of
ActivatorActivator
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTSCONTENTS
 IntroductionIntroduction
 Modifications used in correction of Class IIModifications used in correction of Class II
division1division1
 Modifications used in correction of Class IIModifications used in correction of Class II
division 2division 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)
 Harvold Woodside Activator (1963)Harvold Woodside Activator (1963)
 The Karwetzky appliance (1964)The Karwetzky appliance (1964)www.indiandentalacademy.comwww.indiandentalacademy.com

 The propulsor(1968)The propulsor(1968)
 Wunderer’s modification (1971)Wunderer’s modification (1971)
 Reduced activator of Cybernator of SchmuthReduced activator of Cybernator of Schmuth
(1973)(1973)
 The cutout (or) palate free activator (1968)The cutout (or) palate free activator (1968)
 Magnetic activator device (1993)Magnetic activator device (1993)
 Stockli & TeuscherStockli & Teuscher
 Stockfish’s KinetorStockfish’s Kinetor
 ReferencesReferences

IntroductionIntroduction

 In a clinical study undertaken by Ahlegren,In a clinical study undertaken by Ahlegren,
50 consecutive cases50 consecutive cases
 25 boys and 25 girls25 boys and 25 girls
 The mean age of the group was 9 years,The mean age of the group was 9 years,
ranging from 7 years to 14 years.ranging from 7 years to 14 years.
 Treatment time varied from 1 year to 8Treatment time varied from 1 year to 8
years, with a mean of 3 years, 2 months.years, with a mean of 3 years, 2 months.

Two DevelopmentsTwo Developments
Increased interocclusal distance
Improved retention
Increased efficiency
Bulk Incorporation
Of
appurtenances

 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.

Rigid applianceRigid appliance
No muscle shorteningNo muscle shortening
Isometric contractionIsometric contraction
Myotatic reflexMyotatic reflex
Musculoskeletal adaptation by a new mandibularMusculoskeletal adaptation by a new mandibular
closing patternclosing pattern

Sagittal section through anterior regionSagittal section through anterior region

CORRECTION OF CROSSCORRECTION OF CROSS
BITEBITE
Lingual bow spring
Labial wire loop

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)

Eschler’s Modification (1952)Eschler’s Modification (1952)

HERREN’S DENTOFACIALHERREN’S DENTOFACIAL
ORTHOPEDICS (1953)ORTHOPEDICS (1953)
 By Paul Herren, a young graduate of theBy Paul Herren, a young graduate of the
University of Zurich Dental SchoolUniversity of Zurich Dental School

Selmer- Olsen, Herren, HarvoldSelmer- Olsen, Herren, Harvold
and Woodsideand Woodside
Rigid appliance (PRP)Rigid appliance (PRP)
No muscle shorteningNo muscle shortening
Isometric contractionIsometric contraction
Myotatic reflexMyotatic reflex
Musculoskeletal adaptationMusculoskeletal adaptation
by a new mandibularby a new mandibular
closing patternclosing pattern
Dislocation of mandibleDislocation of mandible
anteriorly or openinganteriorly or opening
beyond the postural restbeyond the postural rest
positionposition
Stretching of soft tissues orStretching of soft tissues or
viscoelastic properties ofviscoelastic properties of
tissuestissues
Muscle tensionMuscle tension
Build up of potential energyBuild up of potential energy
K .E P.E

Deep Bite

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

Activator Active Plate

Cross section through the molarCross section through the molar
region Of the 0ral cavityregion Of the 0ral cavity
Guide the mandibular
Arch in its path to
Proper position

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

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.

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

HARVOLD WOODSIDEHARVOLD WOODSIDE
ACTIVATOR (1963)ACTIVATOR (1963)
 Viscoelastic properties of muscle & theViscoelastic properties of muscle & the
stretching of soft tissues are decisive factorsstretching of soft tissues are decisive factors
for activator action.for activator action.
 Thus the forces responsible for moving theThus the forces responsible for moving the
teeth in activator therapy are not due toteeth in activator therapy are not due to
muscle function per se but to the stretchingmuscle function per se but to the stretching
of soft tissues.of soft tissues.

SleepSleep
Mandible drops openMandible drops open
Appliance may fall out IneffectiveAppliance may fall out Ineffective

 Maximal mandibular protrusion minusMaximal mandibular protrusion minus
3mm3mm
 Vertical bite 8-10mm > than inter-occlusalVertical bite 8-10mm > than inter-occlusal
space i.e. average of 12-15mmspace i.e. average of 12-15mm

Dislocation of mandible anteriorly or openingDislocation of mandible anteriorly or opening
beyond the postural rest positionbeyond the postural rest position
Stretching of soft tissues or viscoelastic propertiesStretching of soft tissues or viscoelastic properties
of tissuesof tissues
Muscle tensionMuscle tension
Build up of potential energyBuild up of potential energy
Without motor activationWithout motor activationwww.indiandentalacademy.comwww.indiandentalacademy.com

 More these muscles are stretched, theMore these muscles are stretched, the
greater is force delivered to the activatorgreater is force delivered to the activator
 Force = swallowingForce = swallowing
bitingbiting
myotatic reflexmyotatic reflex
viscoelastic propertiesviscoelastic properties

Clasp knife reflexClasp knife reflex

 CLASS II DIV 1 CASES WITHCLASS II DIV 1 CASES WITH
VERTICAL GROWTH PATTERN.VERTICAL GROWTH PATTERN.
This case can not be improvedThis case can not be improved
significantly sagitally by anteriorsignificantly sagitally by anterior
positioning of mandible.positioning of mandible.

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)

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

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

 Eliminates any functional retrusion tendenciesEliminates any functional retrusion tendencies
 Offsets any functional dominance of posteriorOffsets any functional dominance of posterior
temporalis fibers which is so often seen in classictemporalis fibers which is so often seen in classic
Class II, Division 1 malocclusions.Class II, Division 1 malocclusions.
 The acrylic between the occlusal surfaces of theThe acrylic between the occlusal surfaces of the
first molars serves to stabilize the appliance whenfirst molars serves to stabilize the appliance when
therapy is initiated.therapy is initiated.
 As treatment progresses, however, this acrylic isAs treatment progresses, however, this acrylic is
removed progressively to allow for unhinderedremoved progressively to allow for unhindered
eruption of the molars and resultant reduction oferuption of the molars and resultant reduction of
the deep overbite, if it exists.the deep overbite, if it exists.www.indiandentalacademy.comwww.indiandentalacademy.com

CUT- OUT OR PALATE-FREECUT- OUT OR PALATE-FREE
ACTIVATORACTIVATOR
 By Metzelder (1968)By Metzelder (1968)
Acrylic covers only palatal or
lingual aspects of the buccal
teeth and a small part of the
adjoining gingiva

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
(1955)(1955)

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

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

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

Magnetic activator device (MAD)Magnetic activator device (MAD)
Darendeliler and Joho (1993)Darendeliler and Joho (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 (SmCo17) magnets areSamarium cobalt (SmCo17) 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

 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 describedPfeiffer and Grobety (1982) have described
combination activator — cervical headgearcombination activator — cervical headgear
therapy.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
retrognathismretrognathism

 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 tubes attachedThe inner bow is inserted into buccal tubes attached
to the maxillary first molars and the outer bow isto the maxillary first molars and the outer bow is
adjusted to about 5° below the inner bow.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.the center of resistance of the molar teeth.
 During treatment, once a Class I molar occlusionDuring treatment, once a Class I molar occlusion
has been established, the outer bow is raised abovehas been established, the outer bow is raised above
the inner bow if uprighting of the molars is indicated.the inner bow if uprighting of the molars is indicated.

 The neck strap produces a force ofThe neck strap produces a force of
approximately 400 grams, measuredapproximately 400 grams, measured
unilaterally.unilaterally.
 Patients are instructed to wear thePatients are instructed to wear the
appliances simultaneously for 14appliances simultaneously for 14
continuous hours a day. Patients are seencontinuous hours a day. Patients are seen
about once every 6 weeks, at which timeabout once every 6 weeks, at which time
the necessary adjustments are madethe necessary adjustments are made

• 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

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

ConclusionConclusion
 Modifications according to the malocclusion.Modifications according to the malocclusion.
 Patient compliance is one of the mostPatient compliance is one of the most
important factors.important factors.

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

 Source: JCO on CD-ROMSource: JCO on CD-ROM
(Copyright © 1998 JCO, Inc.),(Copyright © 1998 JCO, Inc.),
Volume 1968 Jan(28 - 36):Volume 1968 Jan(28 - 36):
Removable Appliance TherapyRemovable Appliance Therapy
- DR. WILLIAM GROSSMAN,- DR. WILLIAM GROSSMAN,
DR. JAMES P. MO.DR. JAMES P. MO.
 ----------------------------------------------------------------
 Fig. 3 Models of a Class II/IFig. 3 Models of a Class II/I
case. (a) In individualcase. (a) In individual
occlusion. (b) With workingocclusion. (b) With working
bite in position. (Note thatbite in position. (Note that
disto-occlusion has beendisto-occlusion has been
corrected to a neutro-corrected to a neutro-
occlusion. The perpendicularocclusion. The perpendicular
line indicates the forwardline indicates the forward
positioning of the mandible topositioning of the mandible to
correct the disto-occlusion.)correct the disto-occlusion.)

 Source: JCO on CD-ROMSource: JCO on CD-ROM
(Copyright © 1998 JCO, Inc.),(Copyright © 1998 JCO, Inc.),
Volume 1980 Aug(529 - 545):Volume 1980 Aug(529 - 545):
Activators for the FixedActivators for the Fixed
Appliance Orthodontist.Appliance Orthodontist.
 ----------------------------------------------------------------
 Fig. 2 Cross section of anFig. 2 Cross section of an
activator showing the eruptionactivator showing the eruption
pattern of teeth for a Class IIpattern of teeth for a Class II
deep bite case. All teeth aredeep bite case. All teeth are
indexed in the acrylic, exceptindexed in the acrylic, except
the lower posterior teeth.the lower posterior teeth.
Dotted lines show possibleDotted lines show possible
force vectors from a directionalforce vectors from a directional
headgear.headgear.

Modifications of Activator

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