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Activator and its modifications
Contents
• Introduction
• Activator
Introduction
• In the past 20 years there has been increasing awareness of
  growth modifications produced by functional appliances
  among orthodontists.

1.   FORM & FUNCTION
2.   NEUROMUSCULAR INVOLVEMENT
3.   IMPORTANCE OF AIRWAY
4.   understanding of HEAD POSTURE AND ITS ROLE
HISTORY AND EVOLUTION OF
            ACTIVATOR
• KINGSLEY introduced "Jumping of the bite”1879 - to
  correct sagittal relationship between Upper and lower
  jaws.

• HOTZ modified the kingsley's plate into a vorbissplate
  (used it for deep bite and retrognathism).

• From Kingsley's concept, VIGGO ANDRESEN 1908
  developed a loose fitting appliance on his daughter as a
  retainer during summer vacations which gave remarkable
  results. He called it BIOMECHANICAL RETAINER.
• PIERRE ROBIN - monobloc to position the mandible
  forward to prevent occluding the airway in patients of
  GLOSSOPTOSIS.

• KARL HAUPL (a periodontist and histologist) became
  convinced that appliance induced growth changes in a
  physiological manner.

• Then the name ACTIVATOR or Norwegian system was
  coined.

• This paved way for a series of modifications and an array
  of functional appliances and opened a new area in the field
  of orthodontics-functional jaw orthopedics.
Indications
• Actively growing individual with favorable (horizontal)
  growth pattern.
• Well aligned maxillary and mandibular teeth
• Mandibular incisors should be upright over the basal bone.

Used In
• Class II Div 1
• Class II Div 2 after aligning the incisors
• Class III
• Class I open bite
• Class I deep bite
• For cross bite correction (Trimming done in such a way
  that maxillary molars are moved laterally and mandibular
  molars lingually).
• Preliminary before Fixed appliance to improve skeletal jaw
  relationship.
• For post- treatment retention
• Used for opening the space for 1st or 2n premolars by using
  jack screws.
• Simultaneously serves as a space maintainer in mixed
  dentition, the acrylic is extended into the space of missing
  tooth.
• Treatment of snoring. Found to be more effective than soft
  palate lifter mouth shield (Swedish dental journal - 1996 -
  20 (5))
CONTRA INDICATIONS
1.   Class I crowding, due to tooth size jaw discrepancy
2.   Increased lower facial height.
3.   Extreme vertical mandibular growth
4.   Severely procumbent lower incisors
5.   Nasal stenosis.
6.   Non growing individuals
Efficacy of Activator:
According to Andresen & Haupl,
 Activator is effective in exploiting the interrelationship
   between FUNCTION and changes in INTERNAL BONE
   STRUCTURE.

 During GROWTH, there is also interrelationship between
  FUNCTION and EXTERNAL BONE FORM.

 The CONDYLAR ADAPTATION to the anterior
  positioning of the mandible consists of growth in an
  upward and backward direction to maintain the integrity
  of TMJ. This adaptational process in induced by the loose
  fitting appliance.
Classification of views
₰ PETROVIC (1984): McNAMARA (1973)
Andresen Haupl's Concept that MYOTATIC reflex activity
  and ISOMETRIC CONTRACTION induce
  musculoskeletal adaptation by introducing a new
  mandibular closing pattern.

• Superior head of lateral pterygoid plays an important role
  in assisting the skeletal adaptations.

• Pertovics research on condylar cartilage growth
  stimulation is by activating the lateral pterygoid.
₰ SELMER - OLSEN, HERREN 1953, HARVOLD 1974 &
  WOODSIDE 1973 do not agree with the myotactic reflex.

According to their views,
• VISCOELASTIC PROPERTIES OF MUSCLE AND
  STRETCHING OF SOFT TISSUES are decisive for
  activator action.

• Each application of force induces secondary forces in
  tissues which inturn introduces a bio-elastic process and
  that is important in stimulating skeletal adaptation.
Stages of Visco-Elastic Reaction (Depends on magnitude
   and duration of applied force)

   Empting of vessels
   Pressing out of interstitial fluid
   Stretching of fibres
   Elastic deformation of bone
   Bioplastic adaptation

• Woodside recommends opening the mandible upto 10-
  15mm with the construction bite.
• SCHMUTH, WITT AND KOMPOSCH feel displacing
  mandible 4 - 6 mm below intercuspal position to be ideal.
  Observed long periods of continuous pressure from
  mandibular teeth against the activator.

• ESCHLER 1952 refers to opening the vertical dimension
  beyond 4mm in construction bite as the "muscle stretching
  method" which works alternatively with isotonic and
  isometric contractions.
Force analysis in activator
               therapy
• When functional appliance activates the muscles, various
  types of forces are created - STATIC , DYNAMIC and
  RHYTHMIC forces.

 Static forces are permanent (eg. force of gravity, posture,
  elasticity of soft tissues and muscles)
 Dynamic forces are interrupted (eg. movements of head
  and body, swallowing)
 Rhythmic forces are associated with respiration and
  circulation. Mandible transmits rhythmic vibrations to the
  maxilla.
Effectiveness of activators during
              sleep
• Serves as a "Night Guard" preventing deleterious nocturnal
  parafunctional activity and stimulating normal muscle
  activity

• Protracted, unloaded condyle enhances condylar growth
  increments and favourable upward and backward growth
  direction.
• HOTZ, PETROVIC, OUDET, STUZMANN stated that
  growth increments were greater at night due to increased
  growth hormone secretion.

• SELMER-OLSEN said that the muscles could not be
  stimulated during sleep as nature has designed them to be
  at rest. Swallowing occurred only 4-8 times in an hour
  during night.

•      Electromyographic study of temporalis and masseter
    with and without activators (AJO - Aug 1998)
• It is observed that there was
1. Similar postural activity for both muscles with or without
   activator.
2. During swallowing of saliva, muscle activity was higher
   with the activator.
3. During maximal clenching similar activity in anterior
   temporalis with or without activator. Higher activity in
   masseter muscle with the activator.
• Two principles employed in modern activator

   – FORCE APPLICATION - the source is usually
     muscular
   – FORCE ELIMINATION - dentition is shielded from
     normal and abnormal functional tissue pressures by
     pads, shields and wires.
TYPES OF FORCES EMPLOYED IN
      ACTIVATOR THERAPY
• Growth potential includes eruption and migration of teeth
  which produces natural forces and those can be
  guided, promoted and inhibited by the activator.
• Muscle contraction and stretching of soft tissues produces
  artificial forces effective in all three planes. Sagittal plane
  - mandible propelled down and forward so that force is
  delivered to the condyle. Vertical plane - teeth and
  alveolar process either loaded or relieved of normal forces.
  Transverse plane - forces can be created with midline
  reactions.
According to WITT,
• Approximate sagittal force     315 - 395gms.
• Optimal vertical force     70 - 175 gms.

• In a study by NORO et al (AJO - 94 Feb) magnitude of
  forces generated by passive tension of soft tissues
  increased from 80 - 160 gms in class II patients and 130 -
  200 gms in class III patients when the construction bite
  heights changed from 2 to 8mm.
DIAGNOSTIC PREPARATION
• Treatment Timing: - MIDDLE to LATE MIXED
  DENTITION.
• : Study Model Analysis
• FUNCTIONAL ANALYSIS
• CEPHALOMETRIC ANALYSIS
• VTO -
construction bite
• ANTERIOR POSTIONING OF MANDIBLE
•      The usual intermaxillary relationship for average class
  II problems is END TO END INCISAL. It should not
  exceed 7 to 8mm or 3/4 of mesiodistal dimension of first
  permanent molar.
OPENING THE BITE
•      To determine the height of the bite
• Mandible should be dislocated from its postural rest
  position in atleast one direction - SAGITTAL or
  VERTICAL

• If the forward positioning is great, vertical opening should
  be minimum (for example - when the forward positioning
  is 7 to 8mm vertical opening should be 2 to 4 mm. If the
  forward positioning is reduced to 3 to 5 mm vertical
  opening is increased to 4 to 6 mm ).
ANDRESON APPLIANCE

• Vertical opening is within the limits of free way space ( 2
  to 4 mm).

• Mandibular advancement being 3 to 5 mm.

• Used for less severe class II MO with deep bite and upright
  or lingually inclined lower incisor.
MODUS OPERANDI
•        The appliance induces activation of MYOTACTIC
    REFLEX & ISOMETRIC CONTRACTIONS. These
    muscle forces are transmitted by the appliance to move the
    teeth. Thus the appliance uses KINETIC ENERGY.

• REFLEX CONTROL OF SKELETAL MUSCLE
  CONTRACTION
• MECHANISM OF STRETCH OR MYOTACTIC
  REFLEX
•      Stretch reflex when elicited causes contraction of the
  stretched muscle. Muscle stretch receptors are
  proprioceptive nerve endings called muscle spindles
  situated within the muscle.
MUSCLE SPINDLES

2-15 THIN INTRAFUSAL         NUCLEAR BAG REGION
MUSCLE FIBERS                 (non contractile)

                               Impulses arise

                         Group I A sensory fibre

                                 ' ' efferents

                       supply the extra fusal muscle fibre

           CONTRACTION OF STRETCHED MUSCLE.
HARVOLD WOOD-SIDE
              ACTIVATOR
• The mandible is placed approximately 3mm distal to the
  most protrusive position sagitally and vertically an extreme
  separation of 10 to 15mm beyond the free way space.

MODUS OPERANDI
•      Here the mandible is opened beyond 4mm so it does
  not work in the same manner as Anderson's activator but
  by stretching of soft tissue - THE VISCO ELASTIC
  EFFECT. In such cases CLASP - KNIFE REFLEX plays
  a role.
• MECHANISM OF CLASP KNIFE REFLEX OR
  AUTOGENIC INHIBITION
Example: Spastic limb Resistance encountere

                   Hyperactive reflex contraction

                      Limb collapses readily

 This phenomena is called CLASP KNIFE RIGIDITY (i.e.
            muscle first resists and then relaxes)
• Stimulus is EXCESS STRETCH when elicited leads to
  muscle relaxation. Receptors are Golgi tendon organs
  situated in the muscle.

• Impulses conducted by group I B sensory nerve fibre act
  on motor neuron or ' ' efferent supplying the stretched
  muscle .

•  It is a DISYNAPTIC REFLEX ARC because an INTER
  NEURON is interposed between sensory and motor
  neuron.
• Functional significance :- is to protect overload by
  preventing damaging contractions against strong stretching
  force.
H - ACTIVATOR
• Activator constructed with LOW VERTICAL OPENING
  and a markedly forward mandibular positioning is
  designated as horizontal or 'H' activator
Indications:
1. Class II Div 1 with sufficient overjet
2. Class II Div 1 MO where there is mandibular overclosure
    that results in a functional retrusion of the mandible. In such
    cases activator can act in the sense of "Jumping the bite"
3. Class II Div 1 MO with posteriorly positioned mandible
    due to growth deficiency with horizontal growth pattern.
       • As a mandible moves mesially to engage the appliance, elevator
         muscle of mastication get activated.

       • When teeth engage the appliance MYOTACTIC REFLEX is
         activated.

       • In addition muscle force arising during biting and swallowing
         causes stimulation of muscle spindles which elicits reflex muscle
         activity.
Effects of H - activator
1. Mandible can be postured forward without tipping the
   lower incisors labially.
2. LIP TRAP got eliminated
3. Maxillary incisors can be positioned upright or lingualy
4. Anterior growth vector of maxilla is slightly inhibited.



Class II Div 1 MO with vertical growth pattern when treated
  with H activator results in DUAL BITE.
V-ACTIVATORS
• Activator with large vertical opening and minimal anterior
  positioning is designated as V activator.

•   Mandible is positioned anteriorily only 3-5mm ahead of
    habitual occlusion.




• Vertical opening 4 to 6mm beyond the postural rest position.
MODUS OPERANDI

•       Induces myotactic reflex activity.

•    The greater vertical opening thus allows the myotactic
    reflex to remain operative even when the musculature is
    more relaxed ( that is when the patient is sleeping).

• Stretching of muscles and soft tissue elicits an additional
  force - the viscoelastic force. This stretch reflex influences
  inclination of maxillary base.
Deep bite MO.
• In dentoalveolar problems, the deep overbite may be due to
  infra-occlusion of buccal segments or supra - occlusion of
  anterior segments.

• Construction bite may be moderate or high depending on
  the free way space.

• If it is due to supra - occlusion of anterior segments,
  interocclusal space is usually small and should resort to
  high construction bite.

• Intrusion of incisors is possible to only a limited extent
  when an activator in being used.
• Skeletal deep bite MO's have a horizontal growth
  pattern, for which forward inclination of maxillary base
  can compensate.

• Loading the incisors can achieve a slight forward
  inclination of the maxillary base as well as frees the molars
  to erupt.

• Here the construction bite is high (5 to 6mm beyond the
  free way space ).

• A dento alveolar compensation is possible by extrusion of
  lower molars and distal driving of upper molars with
  stabilizing wires.
Open bite MO
• Anterior positioning of mandible is necessary if the
  skeletal relationship is orthognathic.

• Bite is opened 4 to 5mm to develop a sufficient elastic
  depressing force and load the molars that are in premature
  contact.
Arch length deficiency problems
• MO with crowding can sometimes be treated with the
  activator and can accomplish the desired expansion
  because it is anchored intermaxillarly.

• The appliance works in a manner similar to that of two
  active plates with jackscrews in upper and lower parts.

• Construction bite should be low.
Construction bite for CLASS III
                   MO
• Goal is posterior positioning of mandible or maxillary
  protraction.

• The construction bite taken by retruding the lower jaw.
  Extent of vertical opening depends on the retrusion possible.

• In PSEUDO CLASS III, functional deviation is present where
  the forced bite is easily achieved.
•      In these cases vertical opening is for enough to clear the
  incisal guidance for construction bite. Here it is possible to
  achieve edge to edge bite relationship with posterior teeth still
  out of contact.
Fabrication of the activator
• Primary wire elements are the UPPER OR LOWER
  LABIAL BOW.
• Upper (U) loop starts in lateral incisors canine embrasure
  area.
• Lower canine loops starts more distally is mesial third of
  the canines.

• Labial bows can be active or passive.

•   If active made out of 0.9mm if passive made out of
    0.8mm.
• Fabrication of the acrylic parts consist of UPPER ,
  LOWER AND INTER OCCLUSAL PARTS.
• Upper and lower parts consist of DENTAL AND
  GINGIVAL PORTIONS.

• Flanges of upper part extends 8 to 12 mm high in gingival
  area and covers the alveolar crest. Flanges of lower part
  extends 5 to 12mm in gingival area.

• Flange extention is greater in V activators as the patients of
  this category have open mouth postures.
Trimming of the activator
VERTICAL PLANE
Intrusion:- Only limited intrusion is possible. Relative
   intrusion is one of the objectives.
 Incisor intrusion: brought about by
• Loading the incisal edge.
• Labial bow placed in the incisal third.
Molar intrusion brought about by
• Acrylic plate touching only the cusps.
• Acrylic plate ground away from fissures and grooves.

• If larger occlusal surfaces are loaded, reflex opening
  occurs frequently resulting in less depressing action by the
  appliance.
• Extrusion: indicated in OPEN BITE problems.
• Incisor extrusion
   – Labial bow is placed in the gingival 1/3
   – Loading the gingival 1/3 on the lingual surface.
•      Molar extrusion
• Enhancing eruption by grinding the acrylic plate from the
  occlusal surface.
• Acrylic contacting the gingival 1/3 on the lingual surface.
SAGITTAL PLANE
• Protrusion:
1. Loading the lingual surface with acrylic contacts.
2. Screening away lip strains with passive labial bow or lip
   pards. Auxiliaries used are
3. Protrusion springs (0.8mm)
4. Wooden pegs
5. Guttapercha may be added to the lingual acrylic.
• Retrusion:
   – Acrylic trimmed away from behind the incisors.
   – Active labial bow.
• FOR DISTAL MOVEMENT OF THE POSTERIORS
• Guide planes should be on the mesio lingual surfaces.
• Stabilizing wires or spurs can be used
• Active open springs.
TRANSVERSE PLANE
• During selective trimming only the upper or lower molars are
  extruded. After erupting, eruption of antagonist can be
  controlled. Thus both sagittal and vertical relationship can be
  influenced.

•
• Eruption pathway of the molars should be considered.

• "CONTROLLED DIFFERENTIAL ERUPTION
  GUIDANCE" must be employed for the best interdental
  and occlusal plane relationship, particularly in case of flush
  terminal plane relationships, proper selective grinding can
  convert an impending class II or class III MO into class I
  interdigitation.
MODIFICATIONS OF THE
           ACTIVATOR
• Broadly categorized into 2 types
1. Appliances with ONE RIGID ACRYLIC MASS for
   maxillary and mandible arches but with reduced volume
   or bulk.
   – Reduced volume in anterior palatal region to restore
     contact between tongue and palate eg. ELASTIC OPEN
     ACTIVATOR
• Disadvantages : construction bite cannot be opened too
   much vertically
   – Reduction in alveolar region and with a cross-palatal
     wire instead of full acrylic plate. Eg. BIONATOR
• Appliance consisting of 2 parts joined by wire bows.
  Muscle impulse are reinforced by wire elements in the
  design. Eg. SCHWARZ DOUBLE PLATE.
Following are the modifications :
1. Eschler's modification
2. Herren's activator (1953)
3. Herren's shage activator – LSU activator
4. The bow activator of Schwarz
5. Reduced activator of Cybernator of Schmuth
6. The Karwetsky appliance
7. The propulsor
8. The cutout (or) palate free activator
9. Elastic open activator of Klammt
10. Stockfish's Kinetor
11. Hamilton expansion activator system. (or) Bonded
    activator
12. Bionator
13. Combined activator /HG Orthopaedics.
14. MAD – Magnetic Activator Device.
ESCHLER'S MODIFICATION
• ESCHLER'S MODIFICATION of labial bow the
  improved the intermaxillary effectiveness.

• One part was active moving the teeth, other
  passive, holding soft tissues of lower lip away and this
  enhancing the tooth movement desired
HERREN ACTIVATOR 1953
• Herren's concept was in complete opposition to be Kinetic
  concept of Andersen Haupl.

1. Triangular clasps to maxillary dentition.
2. A maximum forward positioning in essential with the
   construction bite around 8-10mm.
3. Garber referred this appliance as a SPLINT and a
   "MYOTNIC" appliance and claimed to exert 500gms of
   continuous force due to stretched muscle.
L.S.U. or Activator of Shaye
• LOUISIANA STATE UNIVERSITY ACTIVATOR is
  essentially a modification of Herren activation.
• In this appliance the lower incisor bite on a plane formed
  by the acrylic.

•    Hence growth in occlusal direction is impeded. The
    eruption of premolars and molars are achieved by selective
    grinding and the occlusal plane is leveled.

• Acc to AUF DE MAUR (1978) & HERREN (1953)
  wearing of this appliance does not bring about any
  increased activity of LPM.
• Herren and L.S.U. activator exert their actions mainly
  through sagittal repositioning of the mandible. These
  appliances have 2 step effects.

1. During wear the more forward positioning of the
   mandible is the cause of reduced growth of LPM
   (Simultaneously) a new sensory engram is formed for the
   new positioning of the lower jaw.

2. When not worn the mandible functions in a more forward
   position in such a way, the retro-discal pad is much more
   stimulated as a result of which earlier beginning of
   condylar chondroblast hypertrophy – and consequently an
   increased growth rate of condylar cartilage takes place.
WUNDERER'S MODIFICATIONS
• Wunderer's modifications is used for class III MO.
  Consists of an activator which was split horizontally, the
  upper and lower halves are connected with a screw which
  is situated in a extension of the mandibular portion behind
  the maxillary incisors.

• By opening the screw, maxillary portion is moved
  anteriorly with a reciprocal backward thrust on the
  mandibular portion.
• To enhance the appliance retention, occlusal surface of
  buccal teeth are covered with acrylic. The construction of
  such an appliance is facilitated by a screw designed by
  WEISE.
THE BOW ACTIVATOR OF
               SCHWARZ
• A.M. Schwarz in 1956. He was influenced by the elastic
  properties of Bimler's appliance and some contributions from
  the Wunderer's appliance.

• It consisted of an activator split into half horizontally and
  connected by an elastic metal bow with a safety pin curve –
  to absorb the shock of jaws during closing. There is a
  possibility of activating only the bow on the side of a
  unilateral distoclusion.

• Construction bite is minimal forward positioning of the
  mandible. Appliance gets easily distorted and so results
  achieved are minimal.
THE REDUCED ACTIVATOR (OR)
    CYBERNATOR OF SCHMUTH
• This was designed by Professor G.P. Schmuth of Bonn.
• Acrylic part is reduced for a manner similar to that of
  bionator.
• Consists of labial wire and coffin spring (1.1mm)
• Slender acrylic part is split in the midline. This avoids
  frequent breakages.
• Construction bite similar to that of an activator was
  preferred. Head-gear tubes may be incorporated into the
  appliance.
THE KARWETSKY APPLIANCE
• Constructed with an improved technique and an apparently
  increased efficiency

• Consists of maxillary and mandibular active plates joined
  by a 'U' bow in region of 1st permanent molars. The plates
  are extended over the occlusal surfaces.

• The height of construction bite is equal to inter occlusal
  clearance.
Depending on the placement of the ends of the 'U' Bow 3
  types have been created.

1. Type–I for Class II MO
2. Type–II for class III
3. Type–III to influence the mandible in a transverse
   direction. Used in facial asymmetry (or) lateral cross-bite
   cases.
• The appliance exerts a delicate influence on the dentition
  and on the TMJ.

• Can be combined simultaneously with fixed appliance
  particularly when there are severe rotations.

• With patient co-operation correction can be achieved rather
  quickly    5 – 8 months in favourable cases.

• Duration of wear : atleast 3 hours during the day and
  during sleeping hours.
CUTOUT OF PALATE FREE
               ACTIVATOR
• Developed by Metzelder.

• He combines bionator with original Anderson Haupl
  activator.
• Mandibular part is the same as activator. In maxillary portion
  acrylic covers only palatal or lingual aspect of buccal teeth.
  There is no palatal coverage and coffin springs to lend
  strength and stability.
• It can be worn both during day and night. Bite taken in edge
  to edge incisal relationship. Different types of possibilities of
  treatment are made according to the principles established by
  Balter.
ELASTIC OPEN ACTIVATORS
• This another daytime activators designed by G. Klammt of
  Gorlitz The appliance consists of bilateral acrylic parts (an
  upper and lower labial wire, a palatal arch and guide wires
  for the upper and lower anteriors).

• EOA can be used for various MO including extraction
  cases. Flat acrylic surface permits closure of spaces created
  by extraction since there is no interference in the
  interproximal area.
ELASTIC ACTIVATOR FOR
          TREATMENT OF OPEN BITE
          BJO 1999 – Stellzig, Steegmayer
• The rigid intermaxillary acrylic of lateral occlusal zones is
  replaced by elastic rubber tubes.

• By stimulating the orofacial muscular system by
  ORTHOPEDIC GYMNASTICS (chewing gum effect).
  Activators intrudes upper and lower posterior teeth.

• Possibility of eliminating habits by supplementary
  incorporation of a CRIB.
• Treatment started in the mixed dentition.
• Worn for 14 hours per day, closure of the open bite
  occurred within 8 months of treatment.
• Can be used alone or with HG or FA or as a retention
  appliance.
• A noticeable counter clock-wise rotation of the mandible
  was accomplished by a decrease of gonial angle.
THE KINETOR

• It is also an elastic activator developed by Dr. HUGO
  STOCKFISH in 1951.

• It was combination of functional principles with active
  operation of various screws and spring added to the
  appliance.

• It has the capacity to expand the arches in all 3 directions.
THE PROPULSOR
• this was conceived by MUHLEMAN and refined by HOTZ.
  It is described as a HYBRID APPLIANCE with features of
  both monobloc and simpler oral screen or mask.
• Advantage of the propulsor over activator like appliances :Is
  wide coverage and ability to effect changes in the alveolar
  process.
• Useful in MAXILLARY DENTOALVEOLAR
  PROTRUSION.
• Eliminating any functional retrusive tendencies and offsets
  any functional dominance of posterior temporalis fibers seen
  in class II div 1 MO.
• Construction bite : Similar to an activator but taken in a
  more forward position
• No wire configuration are used with the propulsor
• As intermaxillary relation improves, the appliance is
  reactivated (or) modified by adding acrylic to the area that
  contacts the upper anterior segment.
• Acrylic between the occlusal surface of the first molars
  serves to stabilize the appliance.
• As treatment progresses, acrylic is removed progressively
  to allow for unhindered eruption of molar, thereby
  reducing in the overbite.
HYPER PROPULSOR ACTIVATOR
              1985 Feb – George Gaumond)

• The splint hyperpropulsor activator combined with extra oral
  force is useful in young children with severe overjet and
  overbite who suffer from fractured maxillary incisors at an
  early age (between 6 to 9).

• Appliance is simple, sturdy, well tolerated, acts quickly (6 to
  10 months), inhibits thumb sucking, minimizes tipping of
  incisors and occlusal plane and achieve stable results.

• Consists of a BIMAXILLARY BLOCK OF ACRYLIC
• One must register in wax the relationship of mandible with
  maxilla in maximum hyper propulsion and mouth wide
  open (the only limit the discomfort of the patient) incisal
  edges of upper and lower incisors should be separated by
  12 – 15 mm.
• By virtue of the thickness of acrylic (12-15mm) and a
  high – pull E.O. force, this appliance works efficiently at
  night and does not require day time wear.
• An anterior opening is built into the appliance to facilitate
  breathing.
• Favours mandibular growth, it also inhibits maxillary
  growth. Mandible is displaced anteriorly by the appliance
  and exerts a posterior force on the mandible.
• Upper and lower incisor axes were not altered; occlusal
  plane was not tipped due to the addition of E.O. force.
• Vertical dimension remained unchanged because acrylic
  prevents molar eruption.
• Petrovic et al (1981) showed that HP is effective if
  retrognathism is associated with anterior growth rotation.
BONDED ACTIVATOR
• Designed by HAMILTON who termed it as an expansion
  activation approach.

• This achieves dramatic and rapid correction.

• It is bonded to the maxillary arch and the forward guidance of
  the mandible is achieved by proprioceptive guidance from the
  lingual flanges of the appliances.

• There is no actual joining of maxillary and mandibular
  arches. It is also useful in mixed dentition phase.
COMBINED ACTIVATOR / HG
        ORTHOPEDICS

• Prime target of treatment concept employing activator and
  HG combination is to restrict developmental contributions
  that tend towards a Skeletal class II and to enhance
  developmental contributions that tend to harmonize the AP
  relations of maxillo mandibular structures

• Hasmond introduced this concept in 1969.
• Pfeiffer Grobety (1975) attached facebow directly to the
  activator and applied occipital traction (to prevent the
  undesirable

• Kloehn effect of molar eruption and downward pull of
  anterior end of palatal plane when cervical traction is used)
  to achieve better vertical and rotational control during
  orthopedic class II treatment.
• Thurow incorporated removable acrylic splint in the upper
  arch to obtain enmasse control.

• Face bow was directly incorporated and occipital pull
  applied to restrain downward and forward displacement of
  maxillary complex

• Janson combines bionator with HG.
Indications
• Correction of SK Class II discrepancy in growing patients
  is the operational field of A/HG appliance.

• Reduction of anterior growth vector of maxillary complex
  can be produced relatively well. HG treatment to upper
  arch with heavy forces up to 1000gm per side for 16 hours
  can elicit a maximal maxillary contribution.

• Indicated in SK Class II in which anterior movement of
  chin prominence in desirable and atleast some posteriorly
  directed maxillo dentoalveolar reaction is acceptable.
• Used for class II correction in deciduous, mixed and
  permanent dentition

• High angle cases are particularly domain of this
  combination.

• A/HG – well suited for RETENTION of a corrected class
  II. Stability of the result will depend on the balance
  between growth components of maxilla, dento alveolar
  process and growth contribution of the condyles and
  glenoid fossa. RELAPSE occurs if discordination persists
  after treatment.
Contraindications
• Dental class II situation with a SK. Class I profile should
  not treated with this setup.
• Excessive vertical growth due to structural, muscular or
  functional disturbance cannot be totally regulated with this
  appliance.

• Best treatment timing – will be the EARLY MIXED
  DENTITION stage.
•   E.O. force levels
•   1. Full mixed dentition                 300 to 400mg
•   2. Mixed dentition during exfoliation   150 to 250mg
•     in the upper buccal segments
•   3. Full permanent dentition             400 to 600mg
•   4. Retention                            150 – 400mg
• Two commonly used A/HG combination are
• 1. Pfeiffer Grobetty combination therapy.
• 2. Stockli Teuscher activator therapy.

• A sequence (or) a combination of sequences may be
   required.
1. Preparatory intra-maxillary treatment (W-appliance, rapid
   expansion (RME), utility arches).
2. Sk. Class II correction with A/HG.
3. Intra maxillary detailing and inter-maxillary co-ordination
   (Full FA).
4. Retention of corrected class II with A/HG.
• Frequent combinations 1 & 2 or 3 & 4. In severe cases-
   1,2, 3 & 4.
MAD – MAGNETIC ACTIVATOR
               DEVICE.
•   Magnetic activator device can be used for correction of
•   1. Mandibular lateral deviation   (MAD I)
•   2. Class II MO                    (MAD II)
•   3. Class III MO                   (MAD III)
•   4.Open bite cases                 (MAD IV)

• Magnetic force ranges from 150 – 600gms preside and
  skeletal vs. dental response depends on the intensity of
  magnetic force used.
• Optimum force for 7 to 12 yrs – 300 gms per side.
MAD II – (AJO 1993 : 103 : Ali
       Darendeliler and Jean Pierre Joho)

• Samarium Cobalt (Sm2 Co17) magnets of 4 x 4 x 6x 1 mm
  dimensions were used.

• 30o inclination of occlusal surface of magnet to the basal
  surface produces an OBLIQUE FORCE VECTOR to correct
  class II MO.

• 4mm – buccolingual thickness is only 1mm larger than a std
  edgewise br of the magnet – so size and shape are compatible
  with vestibular shape.
• In class II cases with normal vertical proportions, magnets
  are placed distal to upper canine and distal to lower first
  premolars

• In class II deep bite situations, inclination of the magnets
  and subsequent magnetic force orientation is such that to
  produce dental extrusion in premolar – molar area located
  more posteriorly and produce an ATTRACTING FORCE
  between them
• In class II open bite situation, 2 pairs of lateral magnets is a
  repelling configuration can be used posteriorly – to
  produce molar and premolar intrusion, some distal
  movements in upper arch, pushes the mandible downward
  and forward.
• A pair of attracting magnets located at the retroincisal area
  - help to achieve symmetry, align the upper and lower
  midlines, stabilise the appliace against rippling forces.
MAD IV for skeletal open bite (JCO 1995-
              Sep Darendeliler & Semayuksel

• Consists of removable upper and lower plates.
• Uses NEODYMIUM (Nd2Fe17B) magnets coated with
  stainless steel.
• Consists of 4 posterior repelling magnets which generates a
  force of 300 gms each for introducing the molars.
• 2 anterior attracting midline magnets also generates 300 gms
  force.
• It guides the mandible into centered midline position.
• Exerts an anterior closing effect.
• Enhances ANTERIOR ROTATION OF THE MANDIBLE.
• MAD IVa – used where anterior segment of maxilla is
  vertically correct. (or) overdeveloped gummy smile.
  Anterior magnets in contact.

• MAD IVb – used when additional extrusive effect is
  needed in the maxillary anterior region. Anterior
  magnets placed 2mm apart, posterior magnets in contact
• MAD IVc – used when only anterior extrusion is needed
  posterior magnets are omitted. Anterior magnets 1-2mm
  open

• SKELETAL OPEN BITE cases with high mandible plane
  angles and overbite of –5mm to –1.5mm got reasonably
  well corrected after wearing MAD IV on full-time basis
  (except during meals).
Conclusion
• The individualization of the basic concept of Andersen
  night time application has given a number of clinicians the
  opportunities to express their own biomechanical ability
  and personal preferences for tooth moving appurtenances.

• It is believed that experience will dictate subsequent
  modifications of functional appliances in achieving facial
  balance and harmony during formative years of facial and
  dental development.
References
1. Dentofacial orthopedics with functional appliances (
   Thomas - M.Graber, Thomas Rakosi, Alexander
   petrovic)
2. Removable Orthodontic appliances (T.M.Grater Bedrich
   Neumann)
3. Current orthodontic concepts and Techniques
   (T.M.Graber, Brainerd .F.Swain)
4. Orthodontics - Current Principles and Techniques
   (T.M.Graber, Robert L.Vanarsdall)
5. The Clinical management of Basic maxillofacial
   Orthopedic Appliances (Terrance J.Spahl, John
   W.Witzig)
6. Orthodontic and Orthopedic Treatment in the mixed
   dentition (James -A. Mc.Namara, William L.Brudon).
• Activator's mode of action (AJO July 1959 Volume 45.
  Paul Herren)
• Activator and Electromyographic study - (AJO - Aug 1988)
• Magnitude of forces generated by passive tension of soft
  tissues (AJO -94-Feb)
• Effects of Activator therapy on Dentofacial structures (AJO
  1989 - March. Final review - Bishara & Ziaji)
• Muscle activity during activator treatment (AJO - 1991 -
  April) (Ingervall & Thuer)
• Dual bite - Phantum Activator phenomenon (JCO - 1983
  May - Robert Shaye)
• Effect of Early Activator treatment in patients with class II
  MO. (Evaluated by thin plate Spline Analysis)
  (Christopher.J.Lux, Jan Rubel, Komposch - AO -
  2001:71:120 - 126)

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Activator and its modifications

  • 1. Activator and its modifications
  • 3. Introduction • In the past 20 years there has been increasing awareness of growth modifications produced by functional appliances among orthodontists. 1. FORM & FUNCTION 2. NEUROMUSCULAR INVOLVEMENT 3. IMPORTANCE OF AIRWAY 4. understanding of HEAD POSTURE AND ITS ROLE
  • 4. HISTORY AND EVOLUTION OF ACTIVATOR • KINGSLEY introduced "Jumping of the bite”1879 - to correct sagittal relationship between Upper and lower jaws. • HOTZ modified the kingsley's plate into a vorbissplate (used it for deep bite and retrognathism). • From Kingsley's concept, VIGGO ANDRESEN 1908 developed a loose fitting appliance on his daughter as a retainer during summer vacations which gave remarkable results. He called it BIOMECHANICAL RETAINER.
  • 5. • PIERRE ROBIN - monobloc to position the mandible forward to prevent occluding the airway in patients of GLOSSOPTOSIS. • KARL HAUPL (a periodontist and histologist) became convinced that appliance induced growth changes in a physiological manner. • Then the name ACTIVATOR or Norwegian system was coined. • This paved way for a series of modifications and an array of functional appliances and opened a new area in the field of orthodontics-functional jaw orthopedics.
  • 6. Indications • Actively growing individual with favorable (horizontal) growth pattern. • Well aligned maxillary and mandibular teeth • Mandibular incisors should be upright over the basal bone. Used In • Class II Div 1 • Class II Div 2 after aligning the incisors • Class III • Class I open bite • Class I deep bite
  • 7. • For cross bite correction (Trimming done in such a way that maxillary molars are moved laterally and mandibular molars lingually). • Preliminary before Fixed appliance to improve skeletal jaw relationship. • For post- treatment retention • Used for opening the space for 1st or 2n premolars by using jack screws. • Simultaneously serves as a space maintainer in mixed dentition, the acrylic is extended into the space of missing tooth. • Treatment of snoring. Found to be more effective than soft palate lifter mouth shield (Swedish dental journal - 1996 - 20 (5))
  • 8. CONTRA INDICATIONS 1. Class I crowding, due to tooth size jaw discrepancy 2. Increased lower facial height. 3. Extreme vertical mandibular growth 4. Severely procumbent lower incisors 5. Nasal stenosis. 6. Non growing individuals
  • 9. Efficacy of Activator: According to Andresen & Haupl,  Activator is effective in exploiting the interrelationship between FUNCTION and changes in INTERNAL BONE STRUCTURE.  During GROWTH, there is also interrelationship between FUNCTION and EXTERNAL BONE FORM.  The CONDYLAR ADAPTATION to the anterior positioning of the mandible consists of growth in an upward and backward direction to maintain the integrity of TMJ. This adaptational process in induced by the loose fitting appliance.
  • 10. Classification of views ₰ PETROVIC (1984): McNAMARA (1973) Andresen Haupl's Concept that MYOTATIC reflex activity and ISOMETRIC CONTRACTION induce musculoskeletal adaptation by introducing a new mandibular closing pattern. • Superior head of lateral pterygoid plays an important role in assisting the skeletal adaptations. • Pertovics research on condylar cartilage growth stimulation is by activating the lateral pterygoid.
  • 11. ₰ SELMER - OLSEN, HERREN 1953, HARVOLD 1974 & WOODSIDE 1973 do not agree with the myotactic reflex. According to their views, • VISCOELASTIC PROPERTIES OF MUSCLE AND STRETCHING OF SOFT TISSUES are decisive for activator action. • Each application of force induces secondary forces in tissues which inturn introduces a bio-elastic process and that is important in stimulating skeletal adaptation.
  • 12. Stages of Visco-Elastic Reaction (Depends on magnitude and duration of applied force)  Empting of vessels  Pressing out of interstitial fluid  Stretching of fibres  Elastic deformation of bone  Bioplastic adaptation • Woodside recommends opening the mandible upto 10- 15mm with the construction bite.
  • 13. • SCHMUTH, WITT AND KOMPOSCH feel displacing mandible 4 - 6 mm below intercuspal position to be ideal. Observed long periods of continuous pressure from mandibular teeth against the activator. • ESCHLER 1952 refers to opening the vertical dimension beyond 4mm in construction bite as the "muscle stretching method" which works alternatively with isotonic and isometric contractions.
  • 14. Force analysis in activator therapy • When functional appliance activates the muscles, various types of forces are created - STATIC , DYNAMIC and RHYTHMIC forces.  Static forces are permanent (eg. force of gravity, posture, elasticity of soft tissues and muscles)  Dynamic forces are interrupted (eg. movements of head and body, swallowing)  Rhythmic forces are associated with respiration and circulation. Mandible transmits rhythmic vibrations to the maxilla.
  • 15. Effectiveness of activators during sleep • Serves as a "Night Guard" preventing deleterious nocturnal parafunctional activity and stimulating normal muscle activity • Protracted, unloaded condyle enhances condylar growth increments and favourable upward and backward growth direction.
  • 16. • HOTZ, PETROVIC, OUDET, STUZMANN stated that growth increments were greater at night due to increased growth hormone secretion. • SELMER-OLSEN said that the muscles could not be stimulated during sleep as nature has designed them to be at rest. Swallowing occurred only 4-8 times in an hour during night. • Electromyographic study of temporalis and masseter with and without activators (AJO - Aug 1998)
  • 17. • It is observed that there was 1. Similar postural activity for both muscles with or without activator. 2. During swallowing of saliva, muscle activity was higher with the activator. 3. During maximal clenching similar activity in anterior temporalis with or without activator. Higher activity in masseter muscle with the activator.
  • 18. • Two principles employed in modern activator – FORCE APPLICATION - the source is usually muscular – FORCE ELIMINATION - dentition is shielded from normal and abnormal functional tissue pressures by pads, shields and wires.
  • 19. TYPES OF FORCES EMPLOYED IN ACTIVATOR THERAPY • Growth potential includes eruption and migration of teeth which produces natural forces and those can be guided, promoted and inhibited by the activator. • Muscle contraction and stretching of soft tissues produces artificial forces effective in all three planes. Sagittal plane - mandible propelled down and forward so that force is delivered to the condyle. Vertical plane - teeth and alveolar process either loaded or relieved of normal forces. Transverse plane - forces can be created with midline reactions.
  • 20. According to WITT, • Approximate sagittal force 315 - 395gms. • Optimal vertical force 70 - 175 gms. • In a study by NORO et al (AJO - 94 Feb) magnitude of forces generated by passive tension of soft tissues increased from 80 - 160 gms in class II patients and 130 - 200 gms in class III patients when the construction bite heights changed from 2 to 8mm.
  • 21. DIAGNOSTIC PREPARATION • Treatment Timing: - MIDDLE to LATE MIXED DENTITION. • : Study Model Analysis • FUNCTIONAL ANALYSIS • CEPHALOMETRIC ANALYSIS • VTO -
  • 22. construction bite • ANTERIOR POSTIONING OF MANDIBLE • The usual intermaxillary relationship for average class II problems is END TO END INCISAL. It should not exceed 7 to 8mm or 3/4 of mesiodistal dimension of first permanent molar.
  • 23. OPENING THE BITE • To determine the height of the bite • Mandible should be dislocated from its postural rest position in atleast one direction - SAGITTAL or VERTICAL • If the forward positioning is great, vertical opening should be minimum (for example - when the forward positioning is 7 to 8mm vertical opening should be 2 to 4 mm. If the forward positioning is reduced to 3 to 5 mm vertical opening is increased to 4 to 6 mm ).
  • 24. ANDRESON APPLIANCE • Vertical opening is within the limits of free way space ( 2 to 4 mm). • Mandibular advancement being 3 to 5 mm. • Used for less severe class II MO with deep bite and upright or lingually inclined lower incisor.
  • 25. MODUS OPERANDI • The appliance induces activation of MYOTACTIC REFLEX & ISOMETRIC CONTRACTIONS. These muscle forces are transmitted by the appliance to move the teeth. Thus the appliance uses KINETIC ENERGY. • REFLEX CONTROL OF SKELETAL MUSCLE CONTRACTION • MECHANISM OF STRETCH OR MYOTACTIC REFLEX • Stretch reflex when elicited causes contraction of the stretched muscle. Muscle stretch receptors are proprioceptive nerve endings called muscle spindles situated within the muscle.
  • 26. MUSCLE SPINDLES 2-15 THIN INTRAFUSAL NUCLEAR BAG REGION MUSCLE FIBERS (non contractile) Impulses arise Group I A sensory fibre ' ' efferents supply the extra fusal muscle fibre CONTRACTION OF STRETCHED MUSCLE.
  • 27. HARVOLD WOOD-SIDE ACTIVATOR • The mandible is placed approximately 3mm distal to the most protrusive position sagitally and vertically an extreme separation of 10 to 15mm beyond the free way space. MODUS OPERANDI • Here the mandible is opened beyond 4mm so it does not work in the same manner as Anderson's activator but by stretching of soft tissue - THE VISCO ELASTIC EFFECT. In such cases CLASP - KNIFE REFLEX plays a role.
  • 28. • MECHANISM OF CLASP KNIFE REFLEX OR AUTOGENIC INHIBITION Example: Spastic limb Resistance encountere Hyperactive reflex contraction Limb collapses readily This phenomena is called CLASP KNIFE RIGIDITY (i.e. muscle first resists and then relaxes)
  • 29. • Stimulus is EXCESS STRETCH when elicited leads to muscle relaxation. Receptors are Golgi tendon organs situated in the muscle. • Impulses conducted by group I B sensory nerve fibre act on motor neuron or ' ' efferent supplying the stretched muscle . • It is a DISYNAPTIC REFLEX ARC because an INTER NEURON is interposed between sensory and motor neuron. • Functional significance :- is to protect overload by preventing damaging contractions against strong stretching force.
  • 30. H - ACTIVATOR • Activator constructed with LOW VERTICAL OPENING and a markedly forward mandibular positioning is designated as horizontal or 'H' activator
  • 31. Indications: 1. Class II Div 1 with sufficient overjet 2. Class II Div 1 MO where there is mandibular overclosure that results in a functional retrusion of the mandible. In such cases activator can act in the sense of "Jumping the bite" 3. Class II Div 1 MO with posteriorly positioned mandible due to growth deficiency with horizontal growth pattern. • As a mandible moves mesially to engage the appliance, elevator muscle of mastication get activated. • When teeth engage the appliance MYOTACTIC REFLEX is activated. • In addition muscle force arising during biting and swallowing causes stimulation of muscle spindles which elicits reflex muscle activity.
  • 32. Effects of H - activator 1. Mandible can be postured forward without tipping the lower incisors labially. 2. LIP TRAP got eliminated 3. Maxillary incisors can be positioned upright or lingualy 4. Anterior growth vector of maxilla is slightly inhibited. Class II Div 1 MO with vertical growth pattern when treated with H activator results in DUAL BITE.
  • 33. V-ACTIVATORS • Activator with large vertical opening and minimal anterior positioning is designated as V activator. • Mandible is positioned anteriorily only 3-5mm ahead of habitual occlusion. • Vertical opening 4 to 6mm beyond the postural rest position.
  • 34. MODUS OPERANDI • Induces myotactic reflex activity. • The greater vertical opening thus allows the myotactic reflex to remain operative even when the musculature is more relaxed ( that is when the patient is sleeping). • Stretching of muscles and soft tissue elicits an additional force - the viscoelastic force. This stretch reflex influences inclination of maxillary base.
  • 35. Deep bite MO. • In dentoalveolar problems, the deep overbite may be due to infra-occlusion of buccal segments or supra - occlusion of anterior segments. • Construction bite may be moderate or high depending on the free way space. • If it is due to supra - occlusion of anterior segments, interocclusal space is usually small and should resort to high construction bite. • Intrusion of incisors is possible to only a limited extent when an activator in being used.
  • 36. • Skeletal deep bite MO's have a horizontal growth pattern, for which forward inclination of maxillary base can compensate. • Loading the incisors can achieve a slight forward inclination of the maxillary base as well as frees the molars to erupt. • Here the construction bite is high (5 to 6mm beyond the free way space ). • A dento alveolar compensation is possible by extrusion of lower molars and distal driving of upper molars with stabilizing wires.
  • 37. Open bite MO • Anterior positioning of mandible is necessary if the skeletal relationship is orthognathic. • Bite is opened 4 to 5mm to develop a sufficient elastic depressing force and load the molars that are in premature contact.
  • 38. Arch length deficiency problems • MO with crowding can sometimes be treated with the activator and can accomplish the desired expansion because it is anchored intermaxillarly. • The appliance works in a manner similar to that of two active plates with jackscrews in upper and lower parts. • Construction bite should be low.
  • 39. Construction bite for CLASS III MO • Goal is posterior positioning of mandible or maxillary protraction. • The construction bite taken by retruding the lower jaw. Extent of vertical opening depends on the retrusion possible. • In PSEUDO CLASS III, functional deviation is present where the forced bite is easily achieved. • In these cases vertical opening is for enough to clear the incisal guidance for construction bite. Here it is possible to achieve edge to edge bite relationship with posterior teeth still out of contact.
  • 40. Fabrication of the activator • Primary wire elements are the UPPER OR LOWER LABIAL BOW. • Upper (U) loop starts in lateral incisors canine embrasure area. • Lower canine loops starts more distally is mesial third of the canines. • Labial bows can be active or passive. • If active made out of 0.9mm if passive made out of 0.8mm.
  • 41. • Fabrication of the acrylic parts consist of UPPER , LOWER AND INTER OCCLUSAL PARTS. • Upper and lower parts consist of DENTAL AND GINGIVAL PORTIONS. • Flanges of upper part extends 8 to 12 mm high in gingival area and covers the alveolar crest. Flanges of lower part extends 5 to 12mm in gingival area. • Flange extention is greater in V activators as the patients of this category have open mouth postures.
  • 42. Trimming of the activator VERTICAL PLANE Intrusion:- Only limited intrusion is possible. Relative intrusion is one of the objectives. Incisor intrusion: brought about by • Loading the incisal edge. • Labial bow placed in the incisal third. Molar intrusion brought about by • Acrylic plate touching only the cusps. • Acrylic plate ground away from fissures and grooves. • If larger occlusal surfaces are loaded, reflex opening occurs frequently resulting in less depressing action by the appliance.
  • 43. • Extrusion: indicated in OPEN BITE problems. • Incisor extrusion – Labial bow is placed in the gingival 1/3 – Loading the gingival 1/3 on the lingual surface. • Molar extrusion • Enhancing eruption by grinding the acrylic plate from the occlusal surface. • Acrylic contacting the gingival 1/3 on the lingual surface.
  • 44. SAGITTAL PLANE • Protrusion: 1. Loading the lingual surface with acrylic contacts. 2. Screening away lip strains with passive labial bow or lip pards. Auxiliaries used are 3. Protrusion springs (0.8mm) 4. Wooden pegs 5. Guttapercha may be added to the lingual acrylic.
  • 45. • Retrusion: – Acrylic trimmed away from behind the incisors. – Active labial bow. • FOR DISTAL MOVEMENT OF THE POSTERIORS • Guide planes should be on the mesio lingual surfaces. • Stabilizing wires or spurs can be used • Active open springs.
  • 46. TRANSVERSE PLANE • During selective trimming only the upper or lower molars are extruded. After erupting, eruption of antagonist can be controlled. Thus both sagittal and vertical relationship can be influenced. •
  • 47. • Eruption pathway of the molars should be considered. • "CONTROLLED DIFFERENTIAL ERUPTION GUIDANCE" must be employed for the best interdental and occlusal plane relationship, particularly in case of flush terminal plane relationships, proper selective grinding can convert an impending class II or class III MO into class I interdigitation.
  • 48. MODIFICATIONS OF THE ACTIVATOR • Broadly categorized into 2 types 1. Appliances with ONE RIGID ACRYLIC MASS for maxillary and mandible arches but with reduced volume or bulk. – Reduced volume in anterior palatal region to restore contact between tongue and palate eg. ELASTIC OPEN ACTIVATOR • Disadvantages : construction bite cannot be opened too much vertically – Reduction in alveolar region and with a cross-palatal wire instead of full acrylic plate. Eg. BIONATOR
  • 49. • Appliance consisting of 2 parts joined by wire bows. Muscle impulse are reinforced by wire elements in the design. Eg. SCHWARZ DOUBLE PLATE.
  • 50. Following are the modifications : 1. Eschler's modification 2. Herren's activator (1953) 3. Herren's shage activator – LSU activator 4. The bow activator of Schwarz 5. Reduced activator of Cybernator of Schmuth 6. The Karwetsky appliance 7. The propulsor
  • 51. 8. The cutout (or) palate free activator 9. Elastic open activator of Klammt 10. Stockfish's Kinetor 11. Hamilton expansion activator system. (or) Bonded activator 12. Bionator 13. Combined activator /HG Orthopaedics. 14. MAD – Magnetic Activator Device.
  • 52. ESCHLER'S MODIFICATION • ESCHLER'S MODIFICATION of labial bow the improved the intermaxillary effectiveness. • One part was active moving the teeth, other passive, holding soft tissues of lower lip away and this enhancing the tooth movement desired
  • 53. HERREN ACTIVATOR 1953 • Herren's concept was in complete opposition to be Kinetic concept of Andersen Haupl. 1. Triangular clasps to maxillary dentition. 2. A maximum forward positioning in essential with the construction bite around 8-10mm. 3. Garber referred this appliance as a SPLINT and a "MYOTNIC" appliance and claimed to exert 500gms of continuous force due to stretched muscle.
  • 54. L.S.U. or Activator of Shaye • LOUISIANA STATE UNIVERSITY ACTIVATOR is essentially a modification of Herren activation. • In this appliance the lower incisor bite on a plane formed by the acrylic. • Hence growth in occlusal direction is impeded. The eruption of premolars and molars are achieved by selective grinding and the occlusal plane is leveled. • Acc to AUF DE MAUR (1978) & HERREN (1953) wearing of this appliance does not bring about any increased activity of LPM.
  • 55. • Herren and L.S.U. activator exert their actions mainly through sagittal repositioning of the mandible. These appliances have 2 step effects. 1. During wear the more forward positioning of the mandible is the cause of reduced growth of LPM (Simultaneously) a new sensory engram is formed for the new positioning of the lower jaw. 2. When not worn the mandible functions in a more forward position in such a way, the retro-discal pad is much more stimulated as a result of which earlier beginning of condylar chondroblast hypertrophy – and consequently an increased growth rate of condylar cartilage takes place.
  • 56. WUNDERER'S MODIFICATIONS • Wunderer's modifications is used for class III MO. Consists of an activator which was split horizontally, the upper and lower halves are connected with a screw which is situated in a extension of the mandibular portion behind the maxillary incisors. • By opening the screw, maxillary portion is moved anteriorly with a reciprocal backward thrust on the mandibular portion.
  • 57. • To enhance the appliance retention, occlusal surface of buccal teeth are covered with acrylic. The construction of such an appliance is facilitated by a screw designed by WEISE.
  • 58. THE BOW ACTIVATOR OF SCHWARZ • A.M. Schwarz in 1956. He was influenced by the elastic properties of Bimler's appliance and some contributions from the Wunderer's appliance. • It consisted of an activator split into half horizontally and connected by an elastic metal bow with a safety pin curve – to absorb the shock of jaws during closing. There is a possibility of activating only the bow on the side of a unilateral distoclusion. • Construction bite is minimal forward positioning of the mandible. Appliance gets easily distorted and so results achieved are minimal.
  • 59. THE REDUCED ACTIVATOR (OR) CYBERNATOR OF SCHMUTH • This was designed by Professor G.P. Schmuth of Bonn. • Acrylic part is reduced for a manner similar to that of bionator. • Consists of labial wire and coffin spring (1.1mm) • Slender acrylic part is split in the midline. This avoids frequent breakages. • Construction bite similar to that of an activator was preferred. Head-gear tubes may be incorporated into the appliance.
  • 60. THE KARWETSKY APPLIANCE • Constructed with an improved technique and an apparently increased efficiency • Consists of maxillary and mandibular active plates joined by a 'U' bow in region of 1st permanent molars. The plates are extended over the occlusal surfaces. • The height of construction bite is equal to inter occlusal clearance.
  • 61. Depending on the placement of the ends of the 'U' Bow 3 types have been created. 1. Type–I for Class II MO 2. Type–II for class III 3. Type–III to influence the mandible in a transverse direction. Used in facial asymmetry (or) lateral cross-bite cases.
  • 62. • The appliance exerts a delicate influence on the dentition and on the TMJ. • Can be combined simultaneously with fixed appliance particularly when there are severe rotations. • With patient co-operation correction can be achieved rather quickly 5 – 8 months in favourable cases. • Duration of wear : atleast 3 hours during the day and during sleeping hours.
  • 63. CUTOUT OF PALATE FREE ACTIVATOR • Developed by Metzelder. • He combines bionator with original Anderson Haupl activator. • Mandibular part is the same as activator. In maxillary portion acrylic covers only palatal or lingual aspect of buccal teeth. There is no palatal coverage and coffin springs to lend strength and stability. • It can be worn both during day and night. Bite taken in edge to edge incisal relationship. Different types of possibilities of treatment are made according to the principles established by Balter.
  • 64. ELASTIC OPEN ACTIVATORS • This another daytime activators designed by G. Klammt of Gorlitz The appliance consists of bilateral acrylic parts (an upper and lower labial wire, a palatal arch and guide wires for the upper and lower anteriors). • EOA can be used for various MO including extraction cases. Flat acrylic surface permits closure of spaces created by extraction since there is no interference in the interproximal area.
  • 65. ELASTIC ACTIVATOR FOR TREATMENT OF OPEN BITE BJO 1999 – Stellzig, Steegmayer • The rigid intermaxillary acrylic of lateral occlusal zones is replaced by elastic rubber tubes. • By stimulating the orofacial muscular system by ORTHOPEDIC GYMNASTICS (chewing gum effect). Activators intrudes upper and lower posterior teeth. • Possibility of eliminating habits by supplementary incorporation of a CRIB.
  • 66. • Treatment started in the mixed dentition. • Worn for 14 hours per day, closure of the open bite occurred within 8 months of treatment. • Can be used alone or with HG or FA or as a retention appliance. • A noticeable counter clock-wise rotation of the mandible was accomplished by a decrease of gonial angle.
  • 67. THE KINETOR • It is also an elastic activator developed by Dr. HUGO STOCKFISH in 1951. • It was combination of functional principles with active operation of various screws and spring added to the appliance. • It has the capacity to expand the arches in all 3 directions.
  • 68. THE PROPULSOR • this was conceived by MUHLEMAN and refined by HOTZ. It is described as a HYBRID APPLIANCE with features of both monobloc and simpler oral screen or mask. • Advantage of the propulsor over activator like appliances :Is wide coverage and ability to effect changes in the alveolar process. • Useful in MAXILLARY DENTOALVEOLAR PROTRUSION. • Eliminating any functional retrusive tendencies and offsets any functional dominance of posterior temporalis fibers seen in class II div 1 MO.
  • 69. • Construction bite : Similar to an activator but taken in a more forward position • No wire configuration are used with the propulsor • As intermaxillary relation improves, the appliance is reactivated (or) modified by adding acrylic to the area that contacts the upper anterior segment. • Acrylic between the occlusal surface of the first molars serves to stabilize the appliance. • As treatment progresses, acrylic is removed progressively to allow for unhindered eruption of molar, thereby reducing in the overbite.
  • 70. HYPER PROPULSOR ACTIVATOR 1985 Feb – George Gaumond) • The splint hyperpropulsor activator combined with extra oral force is useful in young children with severe overjet and overbite who suffer from fractured maxillary incisors at an early age (between 6 to 9). • Appliance is simple, sturdy, well tolerated, acts quickly (6 to 10 months), inhibits thumb sucking, minimizes tipping of incisors and occlusal plane and achieve stable results. • Consists of a BIMAXILLARY BLOCK OF ACRYLIC
  • 71. • One must register in wax the relationship of mandible with maxilla in maximum hyper propulsion and mouth wide open (the only limit the discomfort of the patient) incisal edges of upper and lower incisors should be separated by 12 – 15 mm. • By virtue of the thickness of acrylic (12-15mm) and a high – pull E.O. force, this appliance works efficiently at night and does not require day time wear. • An anterior opening is built into the appliance to facilitate breathing.
  • 72. • Favours mandibular growth, it also inhibits maxillary growth. Mandible is displaced anteriorly by the appliance and exerts a posterior force on the mandible. • Upper and lower incisor axes were not altered; occlusal plane was not tipped due to the addition of E.O. force. • Vertical dimension remained unchanged because acrylic prevents molar eruption. • Petrovic et al (1981) showed that HP is effective if retrognathism is associated with anterior growth rotation.
  • 73. BONDED ACTIVATOR • Designed by HAMILTON who termed it as an expansion activation approach. • This achieves dramatic and rapid correction. • It is bonded to the maxillary arch and the forward guidance of the mandible is achieved by proprioceptive guidance from the lingual flanges of the appliances. • There is no actual joining of maxillary and mandibular arches. It is also useful in mixed dentition phase.
  • 74. COMBINED ACTIVATOR / HG ORTHOPEDICS • Prime target of treatment concept employing activator and HG combination is to restrict developmental contributions that tend towards a Skeletal class II and to enhance developmental contributions that tend to harmonize the AP relations of maxillo mandibular structures • Hasmond introduced this concept in 1969.
  • 75. • Pfeiffer Grobety (1975) attached facebow directly to the activator and applied occipital traction (to prevent the undesirable • Kloehn effect of molar eruption and downward pull of anterior end of palatal plane when cervical traction is used) to achieve better vertical and rotational control during orthopedic class II treatment.
  • 76. • Thurow incorporated removable acrylic splint in the upper arch to obtain enmasse control. • Face bow was directly incorporated and occipital pull applied to restrain downward and forward displacement of maxillary complex • Janson combines bionator with HG.
  • 77. Indications • Correction of SK Class II discrepancy in growing patients is the operational field of A/HG appliance. • Reduction of anterior growth vector of maxillary complex can be produced relatively well. HG treatment to upper arch with heavy forces up to 1000gm per side for 16 hours can elicit a maximal maxillary contribution. • Indicated in SK Class II in which anterior movement of chin prominence in desirable and atleast some posteriorly directed maxillo dentoalveolar reaction is acceptable.
  • 78. • Used for class II correction in deciduous, mixed and permanent dentition • High angle cases are particularly domain of this combination. • A/HG – well suited for RETENTION of a corrected class II. Stability of the result will depend on the balance between growth components of maxilla, dento alveolar process and growth contribution of the condyles and glenoid fossa. RELAPSE occurs if discordination persists after treatment.
  • 79. Contraindications • Dental class II situation with a SK. Class I profile should not treated with this setup. • Excessive vertical growth due to structural, muscular or functional disturbance cannot be totally regulated with this appliance. • Best treatment timing – will be the EARLY MIXED DENTITION stage.
  • 80. E.O. force levels • 1. Full mixed dentition 300 to 400mg • 2. Mixed dentition during exfoliation 150 to 250mg • in the upper buccal segments • 3. Full permanent dentition 400 to 600mg • 4. Retention 150 – 400mg
  • 81. • Two commonly used A/HG combination are • 1. Pfeiffer Grobetty combination therapy. • 2. Stockli Teuscher activator therapy. • A sequence (or) a combination of sequences may be required. 1. Preparatory intra-maxillary treatment (W-appliance, rapid expansion (RME), utility arches). 2. Sk. Class II correction with A/HG. 3. Intra maxillary detailing and inter-maxillary co-ordination (Full FA). 4. Retention of corrected class II with A/HG. • Frequent combinations 1 & 2 or 3 & 4. In severe cases- 1,2, 3 & 4.
  • 82. MAD – MAGNETIC ACTIVATOR DEVICE. • Magnetic activator device can be used for correction of • 1. Mandibular lateral deviation (MAD I) • 2. Class II MO (MAD II) • 3. Class III MO (MAD III) • 4.Open bite cases (MAD IV) • Magnetic force ranges from 150 – 600gms preside and skeletal vs. dental response depends on the intensity of magnetic force used. • Optimum force for 7 to 12 yrs – 300 gms per side.
  • 83. MAD II – (AJO 1993 : 103 : Ali Darendeliler and Jean Pierre Joho) • Samarium Cobalt (Sm2 Co17) magnets of 4 x 4 x 6x 1 mm dimensions were used. • 30o inclination of occlusal surface of magnet to the basal surface produces an OBLIQUE FORCE VECTOR to correct class II MO. • 4mm – buccolingual thickness is only 1mm larger than a std edgewise br of the magnet – so size and shape are compatible with vestibular shape.
  • 84. • In class II cases with normal vertical proportions, magnets are placed distal to upper canine and distal to lower first premolars • In class II deep bite situations, inclination of the magnets and subsequent magnetic force orientation is such that to produce dental extrusion in premolar – molar area located more posteriorly and produce an ATTRACTING FORCE between them
  • 85. • In class II open bite situation, 2 pairs of lateral magnets is a repelling configuration can be used posteriorly – to produce molar and premolar intrusion, some distal movements in upper arch, pushes the mandible downward and forward. • A pair of attracting magnets located at the retroincisal area - help to achieve symmetry, align the upper and lower midlines, stabilise the appliace against rippling forces.
  • 86. MAD IV for skeletal open bite (JCO 1995- Sep Darendeliler & Semayuksel • Consists of removable upper and lower plates. • Uses NEODYMIUM (Nd2Fe17B) magnets coated with stainless steel. • Consists of 4 posterior repelling magnets which generates a force of 300 gms each for introducing the molars. • 2 anterior attracting midline magnets also generates 300 gms force. • It guides the mandible into centered midline position. • Exerts an anterior closing effect. • Enhances ANTERIOR ROTATION OF THE MANDIBLE.
  • 87. • MAD IVa – used where anterior segment of maxilla is vertically correct. (or) overdeveloped gummy smile. Anterior magnets in contact. • MAD IVb – used when additional extrusive effect is needed in the maxillary anterior region. Anterior magnets placed 2mm apart, posterior magnets in contact
  • 88. • MAD IVc – used when only anterior extrusion is needed posterior magnets are omitted. Anterior magnets 1-2mm open • SKELETAL OPEN BITE cases with high mandible plane angles and overbite of –5mm to –1.5mm got reasonably well corrected after wearing MAD IV on full-time basis (except during meals).
  • 89. Conclusion • The individualization of the basic concept of Andersen night time application has given a number of clinicians the opportunities to express their own biomechanical ability and personal preferences for tooth moving appurtenances. • It is believed that experience will dictate subsequent modifications of functional appliances in achieving facial balance and harmony during formative years of facial and dental development.
  • 90. References 1. Dentofacial orthopedics with functional appliances ( Thomas - M.Graber, Thomas Rakosi, Alexander petrovic) 2. Removable Orthodontic appliances (T.M.Grater Bedrich Neumann) 3. Current orthodontic concepts and Techniques (T.M.Graber, Brainerd .F.Swain) 4. Orthodontics - Current Principles and Techniques (T.M.Graber, Robert L.Vanarsdall) 5. The Clinical management of Basic maxillofacial Orthopedic Appliances (Terrance J.Spahl, John W.Witzig) 6. Orthodontic and Orthopedic Treatment in the mixed dentition (James -A. Mc.Namara, William L.Brudon).
  • 91. • Activator's mode of action (AJO July 1959 Volume 45. Paul Herren) • Activator and Electromyographic study - (AJO - Aug 1988) • Magnitude of forces generated by passive tension of soft tissues (AJO -94-Feb) • Effects of Activator therapy on Dentofacial structures (AJO 1989 - March. Final review - Bishara & Ziaji) • Muscle activity during activator treatment (AJO - 1991 - April) (Ingervall & Thuer) • Dual bite - Phantum Activator phenomenon (JCO - 1983 May - Robert Shaye) • Effect of Early Activator treatment in patients with class II MO. (Evaluated by thin plate Spline Analysis) (Christopher.J.Lux, Jan Rubel, Komposch - AO - 2001:71:120 - 126)