The activator is a functional appliance used to correct malocclusions like Class II and Class III. It was developed in the 1930s and works by applying intermittent forces to the jaws via acrylic plates and wires. The appliance is trimmed over time to guide tooth movement into the desired occlusion. Modifications include the Herren appliance for Class II corrections and the Bionator, which relies more on tongue position than external forces. The document provides details on the classification, mechanisms of action, use, and modifications of the activator and Bionator appliances.
2. Introduction and history
• Genes / perioral muscles / dentition
• Ortho- 3rd
order of articulation-Moffett
• Fox–application of extra oral force-1803
• Kingsley –Jumping the bite –1880
• Hotz –Vorbissplatte
• Angle- Cl-II elastics –1907
• Robin-monobloc
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3. Origin of activator
• Modified Kingsley plate retainer
• Biomechanic working retainer –Andresen
• Denmark to Oslo in Norway
• Karl Haupl & Viggo Andresen -activator
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4. Classification
Based on the kind of malocclusion
Activator is best suited for achieving gross changes in
growing patients
– Cl II div I,div II
– Cl III
– Open bite
• Based on various modifications
• Classification of views
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5. Classification of views
• Myotatic reflex activity and isometric contractions
induce musculoskeletal adaptation to new mandibular
closing pattern-Kinetic energy
– Andresen-Haupl –1938-based on ‘shaking of bone
‘hypothesis of Roux 1883
– Petrik 1957
– McNamera –1973
– Petrovic –1984
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6. • Grude 1952-mismatch of bite & mechanism
• Viscoelastic property of muscle and stretching of soft
tissues -potential energy
• Emptying of vessels
• Pressing out of interstitial fluid
• Stretching of fibers
• Elastic deformation of bone
• Bioplastic adaptation of bone
• Selmer,Olsen,Herren 1953-incisal crossbite
• Woodside 1973 10–15 mm vertical opening
• Harvold 1974
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7. • Transitional type of action
• Eschler 1952 muscle stretching method
• Cycle of isotonic and isometric contractions
• Ahlgren’s electromyographic research 1970
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8. • Reiten 1951 –no special histologic results from
use of functional appliances
• Witt 1981, Scmuth 1994,
• Witt & Komposh 1979,
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9. Mechanism of action of activator
The neuromuscular basis
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13. Mechanism of action of activator
• Force analysis
• Static force
• Gravity, posture, elasticity of soft tissues
• Dynamic force
• Swallow, mastication
• Rhythmic force
• Activator works by
• Force application
• Force elimination
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15. • Factors which determine activator function
– Individual facial skeleton
– Growth status
– Nature of malocclusion
– Inter occlusal clearence, head posture
– State of mind ,level of consciousness
– Treatment goal - Constriction bite
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16. Activator therapy
• Diagnostic preparation
• Treatment planning
• Bite registration
• Laboratory procedures
• Management of the appliance
– Trimming of activator
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17. Diagnostic preparation
• History
• Growth status
• VTO -‘instant correction’
• Patient compliance
• Study models
• Molar relations
• Midlines
• Asymmetries
• Curve of spee
• Dental discrepancies
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18. • Functional analysis
• Postural rest position in NHP
• ICP habitual occlusion
• path of closure-Prematurities
• Freeway space –inter occlusal clearence
• TMJ & RCP
• Respiration
• Cephalometric analysis
• Direction of growth
• Position & size of jaw bases
• Morphologic peculiarities of mandible
• Position &inclination of incisors
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19. Treatment planning-constriction
bite
• Low construction bite
with marked forward
positioning
H-activator
• High construction bite
with slight anterior
positioning V-
activator
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20. • Construction bite without forward
mandibular positioning
– Vertical problems
• Deep overbite
• Open bite
– Crowding in mixed dentition
• Construction bite with opening &
posterior positioning of mandible
• Construction bite for asymmetries
• Exaggerated construction bite
• Step wise advancement of bite
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21. Bite registration
• Mark the midlines, molar relation & desired mesial
shift on the cast
• Train the patient after seating him in a upright &
relaxed posture
• Soften a sheet of bees wax roll it (1cm
dia) shape it press it on the lower
arch and mark the midline
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22. • Transfer the wax to the patients
mouth & fit it on the mandible
• Move the mandible as previously
practiced
• Remove the wax chill it & remove
the excess
• Place it on the cast and check
• Replace the hard wax in patients
mouth and check after asking him to
bite hard
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23. Vertical dimension during bite registration
• Postural rest
– Phonetic
– Command
– Non command
– Combined
• In occlusion
• Freeway space
• With the bite
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25. • Preparation of wire elements
• Labial bow –0.9 mm
• Additional wire elements
– Stabilizing wire
– Active springs
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26. • Fixation of jackscrews and wire elements
• Fabrication of acrylic portion
• Finishing and polishing
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27. Management of the appliance
• Insert the appliance & give instructions
• Worn for 2-3 hrs day time in the 1st
week
• Night wear & 1-3hrs day wear for 2nd
week
• Patient recalled for check up on 3rd
week
• Check up appointments every 6 weeks
• Trimming according to the plan
• Activation of wire elements
• Jackscrew activated by pt at 2 weeks interval
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28. Trimming for tooth guidance
• Force application and force elimination
• During use the acrylic areas that contact the teeth are
likely to become polished and shiny
• Acrylic surfaces that transmit the desired intermittent
force and contact the teeth are called guide planes
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29. Trimming for 3-D control
• Trimming the activator for vertical control
– Intrusion of teeth
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30. • Extrusion of teeth
• Selective trimming of activator
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31. Trimming for sagital control
• Incisors
• Protraction of incisors
• Loading
– entire lingual surface
– incisal 3rd
of lingual surface
• Protraction springs
• Wooden pegs
• guttapercha
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32. • Passive bow
• Active bow & its position
• Retrusion of incisors
– Interaction between labial bow and
acrylic decides the type of force and
tooth movement
• Incisal-Crtn at apex
• Gingival –Crtn junction of apex and middle
3rd
• Incisal with fulcrum- Crtn middle 3rd
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33. Importance of lower incisors
• Activator loads the lingual surface of lower incisors
and tips them labially
• If this is necessary labial tipping further enhanced by
loading the lingual area
• Prevent labial tipping by relieving lingual acrylic
• Or by incisal capping
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35. Movement of teeth in transverse
plane
• Asymmetric constriction
bite
• Guide planes loading &
trimming
• Jack screw
• Wire elements
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36. summery
• Cl II div I with hypodivergent jaw bases H-
activator
• Normodivergent
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37. • Cl II div I with hyper divergent jaw bases V
activator
• Cl II div II
• Cl I ,Cl I with deep bite,Cl I with Open bite
• Cross bites
• Cl III
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42. Herren-Shaye activator
• Paul Herren of Zurich
• L.S.U of Robert Shaye
• Mandible positioned 2-3 mm
beyond neutroclusion
• Incisal edges are 2-4 mm apart
• Trangular arrow head clasps
• Lingual flanges
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43. Wunderer activator
• Used for Cl III malocclusion
• Appliance is split horizontally
• Screw is embedded in the
acrylic behind the incisors
• Occlusal surfaces are covered
with acrylic
• Weise screw
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44. Bow activator- A.M.Schwarz
• Upper and lower parts are
connected by a elastic bow
• Transverse mobility is believed to
provide additional stimulus
• Independent expansion is
possible
• Step wise advancement is
possible
• Can be used in unilateral
distoclusion
• Distortion and breakages
common
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45. U-bow activator –Karwetzky
• Maxillary and
mandibular active
plates are joined
in the 1st
perm
molar region
using a U shaped
bow made of
1.1mm ss wire
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55. Stockfisch approach
• Bands on first molar
with tubes to receive
head gear
• Clasp on the kinetor
snaps above the
buccal tube
assemblage
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58. Bonded activator-Hamilton
• Mainly used in non compliant patients
• Used for expansion along with forward
positioning of jaws
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59. Bionator-Balters 1960
• Balters concept-position of the
tongue is decisive
• Equilibrium between tongue and
circumoral muscles is
responsible for shape of dental
arches and inter cuspation
• Bite taken in an edge to edge
relation
– Dorsum of tongue in contact with
soft palate
– Lip closure
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60. Appliance design
• Horse shoe shaped acrylic lingual plate
• Upper anterior part kept free for proper
tongue function
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61. Labial bow with buccinator loops
Palatal bar
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62. Basic Cl II appliance
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64. Class III or reversed bionator
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65. Other differences
• Less bulky more patient compliance
• Can be worn all time except during meals
• Vulnerable to distortion
• Simultaneous requirement of stabilization of
the appliance and selective grinding for
eruption guidence
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66. Ideal cases for bionator therapy
• Mild Cl II in mixed dentition
• Well aligned arches
• Abnormal muscle pattern
• Buccal teeth are in infraclusion,-large freeway
space
• Adults with TMJ problems
• Bruxism and clenching during REM
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67. Terminology used to
describe trimming of
bionator
• Articular plane
• Loading area
• Tooth bed
• Nose
• Ledge
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68. Sequence of trimming of bionator
• Trimming of acrylic and elimination of
influence of tongue and cheeks allow the
teeth to erupt up to the articular plane
• Sequence –lower molar & upper molar-
lower pre molars –upper premolars
• Additional anchorage from
– Lower incisal margins
– Deciduous molars and edentulous areas
– Noses
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69. references
• Dentofacial orthopedics with functional appliances-
Graber,Rakosi & Petrovic
• Removable orthodontic appliances-Graber & Neumann
• Orthodontics- current principles & technique-Graber & Swain
• Orthodontics- current principles & technique-Graber &
Vanarsdall
• Bass Orthopedic Appliance System Part 1 - Design and
Construction - Neville M Bass -JCO April 1987
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