Activator and its modifications /certified fixed orthodontic courses /certified fixed orthodontic courses by Indian dental academy


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Activator and its modifications /certified fixed orthodontic courses /certified fixed orthodontic courses by Indian dental academy

  1. 1. ACTIVATOR AND ITS MODIFICATIONS INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Catch them Young ACTIVATOR AND ITS MODIFICATIONS… Watch them Grow
  3. 3. History… Kingsley(1879) – “ jumping the bite ” Robin 1902- Monobloc. Viggow Andresen (1908) Andresen and Haupl (1955) - Activator.
  4. 4. Mechanism of Action…  MECHANISM OF THE STRETCH (OR) MYOTATIC RELEX:     How does it work? Monosynaptic? Postural rest position? Isometric contractions?
  5. 5. My View…
  6. 6.  Harvold and Woodside ,Herren ,Selmer-Olsen  viscoelastic properties of soft tissue  Rationale?
  7. 7.  Bite registered for 3mm to 4 mm distal to the most protruded position is to avoid the possibility of initiating Golgi tendon organ activity and thus eliminate any undesirable myotatic reflex  Witts supported a combination of isometric muscle contractions and viscoelastic properties being responsible for the forces delivered by the activator and used intermediate construction bite height.  Eschler attributed the muscle contraction to proprioceptive stretch reflexes and observed the occurrence of both isometric and isotonic contraction with use of the activator.
  8. 8. Types of forces in activator therapy  Forces employed in activator therapy are categorized as,  The growth potential, including the eruption and migration of teeth, produces natural forces; these can be guided, promoted and inhibited by the activator.  Muscle contractions and stretching of the soft tissues initiate forces when the mandible is relocated from its postural rest positions by the appliance. Whereas forces may be functional in origin, the activation is artificial.
  9. 9. Artificially functioning forces can be effective in three planes Sagittal plane:  Mandible is propelled down and forward.  muscle force is delivered to the condyle and a strain is produced  Slight reciprocal force can be transmitted to the maxilla during this maneuver. Vertical Plane:  Teeth and alveolar processes are either loaded with or relieved of normal forces.  if construction bite is high, a great strain is produced  if transmitted to the maxilla, these forces can inhibit growth increment and direction and influence the inclination of the maxillary base.
  10. 10. Transverse plane:  Forces can be created with midline corrections.  Various active elements like springs, screws can be built in to the activator to produce an active biomechanical type of force application. The mode of force application, magnitude and direction depend on the three dimensional dislocation of the mandible, which is determined by the construction bite.
  11. 11. Activator  The original appliance consists of a combined upper and a lower plate at the occlusal plane only one-wire elements was used i.e. A labial arch for upper anterior teeth.
  12. 12. Construction Bite ♫ Edge-to-edge incisal relationship to stimulate the mandibular growth. The construction bite for the activators was taken with the lower jaw in class I or over corrected class I molar relationships ♫ Vertical opening not beyond rest position of the mandible
  13. 13. EFFECT OF ACTIVATOR TREATMENT  Skeletal ChangesClass II Div I)  The Skeletal effect of the activator depends on growth potential.  Two divergent growth vectors propel the jaw bases in an anterior direction.  The sphenoccipital synchordrosis moves the cranial base and nasomaxillary complex up and forward  The condyle translates the mandible in a downward and forward direction.
  14. 14.
  15. 15.  In contrast to primary cartilages (epiphyses, sphenoccipital synchondroses) a condylar growth is regulated to a high degree by local exogenous factors.  Petrovic - forward posturing of the condyle activates the superior head of LPM and condylar growth.  The activator can, to a limited degree control the upper growth vector supplied by the sphenoccipital synchondrosis, which moves the maxillary base forward.  Total anterior facial height increases with lower facial height increased by more than twice as much.
  16. 16. ROLE OF RETRODISCAL PAD:  The Retrodiscal pad controls mandibular growth in two ways.  The vascular component controls the condylar cartilage growth rate and endochondral ossification rate.  An increase in interactive activity of the retrodiscal pad produces an increase in condylar cartilage growth and endochondral ossification.
  17. 17.  An increase in interactive activity of the retrodiscal pad -accentuation of the ramus posterior concavity and a local increase in bone apposition and the number of negative charges at the ramus posterior concave surface.  Accentuation of the ramus anterior convexity and local increase in bone resorption and number of positive charges at the ramus posterior convex surface.
  18. 18. Dento Alveolar Effect ♫ The improvement in sagittal occlusal relationship was due about equally to skeletal and dental charges. ♫ Overjet correction- mandibular growth exceeding maxillary growth and distal movement of the maxillary incisors. ♫ Class II molar correction -mandibular growth exceeding maxillary growth and mesial movement of the mandibular molars.
  19. 19. ♫ Inhibits maxillary growth, move the maxillary incisors and molars distally and move the mandibular molars and incisors mesially. ♫ Lingual tipping of maxillary incisors and labial proclination of the mandibular incisors related to significant reductions in overjet. Thus passive upper labial wire of activator intended to avoid upper incisor tipping and acrylic cap on the incisal third of the lower incisors can prevent proclination
  20. 20. Soft tissue changes  Retraction of upper anterior teeth, followed by a similar dropping back of the upper lip, improve a protrusive profile.  Stoner’s and associates found that,  Soft tissue improvements were produced by four principal changes.  The gross movement of incisors  A reduction in the curl of the lower lip.  Vertical opening of the chin.  Forward positioning of the chin.  Reduction of overjet has the effect of uncurling both lips, which enables the lips to hold together without undue effort.
  21. 21.  Class II Div 2 malocclusions  The upper central incisors are tipped labially by springs at the incisal margin.  The labial bow exerts lingual pressure at the labial gingival margins to achieve lingual root movement.(Herren activator preferred)  Open bite and Cross bite?
  22. 22. REVERSE ACTIVATOR  Construction bite  Bite is taken by retruding the jaw. The extent of vertical opening depends on the retrusion possible.
  23. 23. In Functional Protrusion Class III Malocclusion  The mandibular incisor hit prematurely in an end-to-end contact, and the mandible then slides anteriorly to complete the full occlusal relationship.  The vertical dimension of construction bite is opened far enough to clear the incisal guidance, which eliminates the protrusive relationship with mandible in centric relation.  The prognosis for pseudo class III malocclusion is good, especially if therapy is started in early mixed dentition. In early mixed dentition period, skeletal manifestation are not usually severe, since the malocclusion develops progressively.
  24. 24. Appliance  Mandibular labial bow is used to guide the mandible distally, as the teeth occlude.  The maxillary labial bow If needed kept away from labial surfaces to relieve any lip pressure.
  25. 25.  The acrylic was relieved on lingual surface of mandibular incisors and maxillary incisors supported with close contact.  Maxillary incisors are tipped labially with small screws, wooden pegs (or) lingual springs (or) by application of gutta percha lingual to incisors.  Concurrently force was eliminated in the upper arch with maxillary lip pads to allow the fullest extent of growth potential
  26. 26.  Changes  Articular angle increased because of posterior positioning mandible  Mandibular plane angle slightly opened.  SNA increased  ANB increased  Maxillary incisor tipped labially  Mandibular incisors tipped lingually.
  27. 27.  In a skeletal class III malocclusion with a normal path of closure from postural rest to habitual occlusion, the treatment with functional appliance is not always possible.  The true mandibular prognathism is undoubtedly one of the most difficult conditions to treat orthodontically.
  28. 28. HARVOLD – WOODSIDE ACTIVAOR  Harvold (1974) and Wood side (1973)  Wood side opens the mandible with the construction bite as much as to 10 – 15 mm beyond postural rest vertical dimension.  The forces generated by this extreme bite registration (10-15 mm) represent combination of forces generated by swallowing, biting, activation of the myotatic reflex in the stretched muscles of mastication and the power delivered through the viscoelastic properties of stretched muscles, tendon tissue, Skin and musculature.  This appliance works using potential energy.
  29. 29. Class II Div I with increased LAFH (environmental factors)  Actual adaptation of the maxilla to the lower dental arch.  Partially achieved by retroclination of the maxillary base.  Differential eruption of teeth  good vertical control of both dental arches and only minor forward tipping of the lower incisors.
  30. 30.  Harvold has also emphasized the concept of the “Functional occlusal place” and the role played by its manipulation in the successful correction of class II malocclusions. This plane represents the functional table of occlusion in the first permanent molar, second molar and first premolar areas.
  31. 31.  The level and inclination of the functional occlusal plane is the result of the neuromuscular, growth and developmental forces acting on the dentition.  The correct manipulation of the functional occlusal plane involves the inhibition of maxillary buccal segment eruption, which normally follows a downward and forward curvilinear eruption path.  At the same time mandibular buccal segment are permitted to erupt vertically in harmony with the vertical growth of the lower face.  Because the mandibular molar erupt roughly at right angles to the functional plane, change from class II malocclusion to class I occlusion is facilitated.
  32. 32. Appliance with dislodging springs
  33. 33. Class III malocclusion
  34. 34. HERREN ACTIVATOR  The principle-complete opposition to the kinetic concept of Andersen – Haupl appliance.  By overcompensating the ventral position of the mandible in the construction wax bite.  By seating the appliance firmly against the maxillary dental arch by means of arrowhead clasps similar to those used in active plates.
  35. 35. Mode of action  Graber coined the term “myotonic appliance”.  The mandible is prevented from assuming the natural restposition – thus if the rest position prescribed by activator does not coincide with natural rest position, the retractive musculature is stretched.  In Class II malocclusion, the construction bite of the Herren activator dislocates the mandible ventrally, parallel to occlusal plane by a total of 8mm or more. The improvement of post normal occlusion was directly related to the amount of mandibular displacement, in taking the construction wax bite.
  36. 36.
  37. 37.  When the activator is inserted, the mandible is purposely carried forward until it is possible to bite completely in to the positioning splint.  The mandible is kept from being retracted because the activator takes the load of these forces and transmits them in an occipital direction, to the maxillary dental arch.  Since “action equals reaction” a force of equal magnitude but opposite direction acts against the mandibular dental arch.
  38. 38.  The force acts continuously only as long as the Herren or L.S.U activator is in place i.e. 9 – 10 hrs during night.  The activator holds the retractive musculature of the mandible passively stretched.  More over, the activator inserted between the teeth and tongue act as a shield that keeps the tongue away from the free way space, which enables the eruption of the teeth, provided that the acrylic occlusal stops of posterior teeth are ground away from the appliance.
  39. 39.  According to rat studies reported by Petrovic et al, the action of Herren type of activator comprises a two-stage effect.  During the time the activator is worn, the protrusive position of the mandible (caused by construction bite) causes reduced increase in length of the lateral pterygoid muscle and at the same time forms a new sensory “engram” for positioning of the mandible.  This causes the mandible to function in a more forward position during the period when the activator is not worn.  The forward positioning of the mandible by the contraction of the lateral pterygoid muscle, when the activator is not being used causes an accelerated growth rate of condylar cartilage.
  40. 40. Specific features  Twin arrowhead clasp.  Expansion screws.  Lingual springs to correct moderate incisal irregularities.  Extension of the flanges towards the floor of the mouthmandibular anchorage(lower labial bow if needed)  Horizontal slot in maxillary incisors for comfort.  No pathologic changes in TMJ.  Asymmetrical Class II Div I- Expansion screws with asymmetric cuts in the appliance
  41. 41.
  42. 42. Skeletal effect  To correct the class II malocclusion in an expedient, reliable and economic way.  To retard forward growth of the maxilla.  To reposition the mandible through mandibular growth, either in a horizontal or in a vertical direction.  To achieve these performances in the transitional as well as in the early permanent dentition, independent from the pubertal growth peak in body height( by over compensating)  To provide a high rate of stability of the treatment results after several years out of retention.
  43. 43.  Herren activator holds the maxillary dental arch preventing the maxillary forward growth, the mandibular dental arch carried forward together with its basal arch.  The treatment results in,  Increase of SNB angle  Decrease of ANB angle  Mandible length increased (distance measured from middle of the external ear opening & gnathion– from cephalometric head films)  Change in position of the mandible, either a more forward or a more downward direction.
  44. 44. Dental Effect  Dentoalveolar compensation (distal movement of upper molars, mesial movement of the lower molars) appeared to be inversely related to skeletal adaptation.  The correction of molar relationship occurred to 55% by skeletal changes.
  45. 45. Class II Div 2 malocclusions  Herren advocated expansion screws,lingual springs for correction of retruded incisors and guiding spurs to relieve minor crowding.
  46. 46. Class III Malocclusion
  47. 47. Retention • Retention period - (due to over compensation) 15 months after normal (neutral) dental arch relationships is achieved and overjet is corrected. • This normal dental arch relationship is maintained in taking the construction wax bite for a retention activator. However the mandible is carried forward by about 2 mm, beyond neutro occlusion to compensate for the increase in overjet that occurs as a result of rotation of the mandible around the condylar hinge axis when a vertical inter occlusal clearance of 4 – 6 mm is constructed.
  48. 48. Relapse  If, treatment started too an early age, partial relapse occur after retention. It is recommend to start treatment, when premolars have erupted.  Corrections of Antero-posterior basal discrepancy, resulting from this therapy, were shown to be stable even 5 years after the end of retention.
  50. 50. BOW ACTIVATOR  The upper and lower halvesconnected-elastic bow.  It is thus possible to change the relationship of the upper and lower halves of the appliance.  With the treatment of class II division 1 malocclusion, beginning can be made with a small forward positioning, increasing this gradually by a periodic adjustment as recommended by Frankel.
  51. 51.  Taatz (1971) ,  appliances specially suited for treatment of class II division 1 malocclusion in the deciduous dentition.  Small children will have the appliance in place for longer periods of time because they sleep more hours.  Young patients seem to adapt more easily to bringing the mandible forward gradually than to a sudden forward positioning.  Mixed dentition treatment is probably better from both a growth response and a patient compliance standpoint.
  52. 52. REDUCED ACTIVATOR OR CYBERNATOR  Resembles bionator  customary labial wire of the activator is used, as well as most of other simple appurtenances of this and other myofunctional appliances including the coffin spring.  Construction bite?  Advantages?
  53. 53.  Spurs added to prevent the mesial movement of molars during the shedding of deciduous molars.  Can be combined with fixed appliance therapy.  Headgear tubes can be incorporated for extra oral force.
  54. 54. U BOW ACTIVATOR • maxillary and mandibular active plates, joined by a U bow in the region of the first permanent molars. • In addition to acrylic covering of the lingual tissue aspects, gingiva and teeth, plates also extend over the occlusal aspects of all teeth.
  55. 55.  The height of the construction bite is that of interocclusal space or clearance with the mandible in postural rest for the karwetzky appliance.  Thus space varies with the malocclusions.
  56. 56.  U-bow :1 long leg ; 1 short leg .The shorter leg is imbedded in the upper appliance, whereas the longer leg is attached to lower plate.
  57. 57.
  58. 58. Advantages  Combinations of different types of sagittal or transverse screws, labial wires and springs enhance the basic appliance action.  U-bow activator combined with fixed appliance when there are severe rotations or there is need for selective extraction and uprighting of teeth contiguous to extraction site.  Orthognathic surgery in adults like corticotomies and sub apical resections, u bow activator has the potential for use.
  59. 59. PROPULSOR ACTIVATOR  hybrid appliance.  Advantage?  No wire configuration are used with propulsor, acrylic connecting the upper buccal segment to the lower lingual flange also serves as occlusal support to stabilize the appliance
  60. 60.  As treatment progresses this acrylic is removed progressively to allow for unhindered eruption of molars and resultant reduction of the deep overbites, if exists.  Also if selective eruption is desired to reduce the class II buccal segment relationship by upward and forward eruption of the lower teeth while preventing forward eruption of upper teeth by removing acrylic in the opposing lower molar area leaving them free.  The compliance is usually good because of the lightweight &minimum bulk of the appliance.
  61. 61. CUT OUT (or) PALATE FREE ACTIVATOR  Advantage of the Bionator with some of those of the original Andersen – Haupl appliance.  Parts?
  62. 62.  Metzelder changes however do have some advantages.  Appliance is easier to make.  It may carry all the appurtenances described for the activator.  These include  The jackscrew for expansion  Petrik finger spring for moving individual teeth. (upper&lower canine after extraction).  Springs for labial tipping of lower incisors.  Proclining springs for Class II Div 2 cases.
  63. 63.
  64. 64. Open Bite Class III
  65. 65. ELASTIC OPEN ACTIVATOR  The elastic open activator resemble the Bionator, with acrylic anteriorly and with more wires.  The Bionator though free movable in the oral cavity, is carefully stabilized on posterior occlusal surfaces or the lower incisors as the occasion demands.  completely lacks such stabilization and thus its vertical mobility in the mouth is unimpeded.
  66. 66. Mode of Action  The appliance will react to most of the tongue movements and so it must "come to terms" with the tongue.  In this manner, a great number of impulses are transmitted to the teeth, serving as the basis for transformative changes.
  67. 67. Standard EOA  bilateral acrylic parts, an upper and lower labial wire, a palatal arch and guiding wires for upper and lower incisors.  The acrylic parts extend from the canine posteriorly to the point just behind the first or second permanent molar if it is present.  The acrylic is quite thin in order to leave the largest possible space for the tongue. Stabilization of acrylic position is accomplished by means of contact with the lingual surfaces of maxillary and mandibular canines.
  68. 68.  Relieve the crowding  To relieve the crowding of maxillary central incisors, half of maxillary labial wire was omitted, with the other half being used to engage the incisor. On this side, the guiding wire was used only for the opposite side.
  69. 69.  Space maintainer  For example, the second deciduous molar has been lost prematurely. Its space is maintained by an extension of contiguous acrylic; with the flat acrylic surface .a double wire is placed mesial to first molar and distal to first deciduous molars.
  70. 70.  Class II division 1 malocclusion  Construction bite  With an overjet as large as 10mm, it is usually possible to get the incisors in to an edge-to-edge bite.  No TMJ problems, even after such extensive forward positioning of the mandible.
  71. 71. • Class II division 2 malocclusion or Deckbiss
  72. 72.  Class III mal occlusion  Construction bite  Edge to edge bite of the incisors or most retruded mandibular position.  The maxillary labial wire carries lip pads similar to those of Frankel appliance.
  73. 73.  Unilateral cross bite  Construction bite  Bite with slight over correction of the midline is advantageous.  The acrylic closely follows the teeth, except in mandibular part that approximates the teeth in cross bite.
  74. 74. Open Bite
  75. 75. Kinetor- Stockfish  Stockfish- Elastic activatorsemi double plate appliance with latex tubing between the upper and lower components to stimulate function.  Elastic appliance-isotonic muscle contractions-less force magnitude-less effective.  Longer wearing timeefficient.
  76. 76. WUNDERER MODIFICATION OF ACTIVATOR FOR CLASS III MALOCCLUSION  The appliance is split horizontally with the upper and lower portion connected by a screw that is embedded in an acrylic extension of the mandibular portion behind the maxillary incisors.
  77. 77.  As the screw is opened the maxillary portion moves anteriorly with a reciprocal posterior thrust acting on the mandibular dentition. Occlusal surfaces of the posterior teeth are covered with acrylic to enhance retention.  The construction bite for class III case is taken in most retruded or hinge axis position of the mandible with the incisal edges 2mmor 3mm apart.  In addition to maxillary labial bow a mandibular labial bow used to guide the mandible distally as they occlude.
  79. 79. PFEIFFER-GROBETY  A cervical headgear with a long outer bow is used.  The inner bow is inserted into buccal tubes attached to the maxillary first molars and the outer bow is adjusted to about 5° below the inner bow.  This produces a predominantly distal force through the center of resistance of the molar teeth and a lesser vertical extrusive force component .
  80. 80.  The neck strap produces a force of approximately 400 grams, measured unilaterally.  The activator used is based on the design and application described by Harvold and modified for use with a cervical headgear applied to the maxillary first molars.  Brachyfacial and mesofacial types responded most favorably to this combination.  This combination is contraindicated in dolichofacial type, because it results in mandibular clockwise rotation  Duration of wear- 14 continuous hours a day.
  81. 81.  Pfeiffer and Grobety supported combination activator — cervical headgear therapy., for two reasons:  to extrude maxillary molars, and  to apply orthopedic traction to the maxilla and an activator to induce orthopedic mandibular changes, restrain maxillary growth, and cause selective eruption of teeth.  Drawbacks?
  82. 82. STOCKLI-TEUCHER APPROACH  The inner face bow is completely embedded in the labial side of the maxillary splint, and the short outer arms are bent upward depending on the desired angle to the occlusal plane.  Torquing springs, jackscrews, lip pads Can also be incorporated.
  83. 83.  Vertical control  the untrimmed interocclusal acrylic acts as a bite block.  the inclination of the outer face bow precise control over the direction of force, according to the following principles:  A force passing through the center of resistance produces pure translation in the direction of the force.  A force passing at a distance from the center of resistance generates a moment, with a combined effect of rotation (from the moment) and translation (from the force).
  84. 84.  Duration of wear  Active treatment usually takes about 10 months, with the appliance worn at night and for a few hours during the day (1214 hours total per day).
  85. 85. Stockfish & Hickam  Stockfish-Kinetor ( elastic activator ) with high pull headgear attached to the buccal tubes in molar bands.  Hickam- Extraoral force applied to the hooks soldered to the labial bow of the activator- control of the downward and backward rotation of the maxilla and have a restrictive effect on the horizontal and vertical maxillary basal and dentoalveolar components.
  86. 86. Bass Appliance  Neville (1987)- maxillary splint, with an anterior expansion screw and an incisor torquing spring .  Lingual pads for mandibular growth enhancement are slotted into the splint, which also carries detachable side and labial screens.  The appliance system offers considerable flexibility in design, much as with an edgewise approach.
  87. 87.
  88. 88. Trimming of the activator
  89. 89. Pinciples in Trimming  The force is intermittent. This allows dynamic and rhythmic muscle forces to act in such a manner that the appliance acts by kinetic energy.  The direction of the desired force is determined by selective grinding of the acrylic surfaces that contact the teeth.  The magnitude of force is determined by the amount of acrylic that contact the teeth.  The acrylic surface that transmit the force and contact the teeth are called guide planes  Evaluation?
  90. 90. VERTICAL CONTROL  INTRUSION OF TEETH:  Incisors:  Can be achieved by loading the incisal edges of teeth, the labial bow should be below the area of greatest convexity or on incisal third.  Molars:  Performed by loading only the cusps. The pits and fossas are cleared to eliminate any possible incline plane effect
  91. 91. Extrusion of teeth  Incisors:  Requires loading the acrylic above the area of greatest concavity in the maxilla and below this area in the mandible. Although not effective can be enhanced by placing the labial bow above the area of greatest convexity.  Indicated in Open bite problems(finger sucking)
  92. 92.  Molars:  Requires loading the acrylic above the area of greatest convexity in the maxilla and below this area in the mandible.  Indicated in deep bite cases.  Simultaneous extrusion of both the upper and lower buccal segments-no adequate conttrol.
  93. 93. PROTRUSION OF INCISORS  Incisors can be protruded by loading their lingual surface and screening lip strain by passive labial bow.  Entire lingual surface loaded  Incisal third of lingual surface is loaded.
  94. 94. Retrusion of Incisors  Acrylic is trimmed from the back of incisor  Active Labial bow is incorporated
  95. 95. MOVEMENT OF POSTERIORS IN SAGITAL PLANE  Distalization:  the Guide planes are loaded in the mesio lingual surfaces.  Indicated in class II cases.
  96. 96.  Mesial movement:  Can be achieved by loading the disto - lingual surfaces.  Indicated for the upper arch in class III cases.
  97. 97. Movement in transverse plane  To achieve transverse movement the lingual acrylic surfaces opposite to the posterior teeth must be in contact with teeth.  More effective expansion can be achieved using Jack screws.
  98. 98. Activator Trimming in Class II malocclusions  If upper incisors are to be retruded and the labial bow is activeacrylic capping needed to prevent extrusion.  Lower incisor capping needed to prevent lower incisor proclination.  Selective trimming of the acrylic that prevents mesial movement of the upper buccal segments and enhances mesial movement of the lower buccal segment- Class II correction.
  99. 99. Activator Trimming in Class III malocclusions  The upper incisors are loaded for protrusion and labial bow passive.  Lip pads used instead of labial bow to stimulate basal maxillary development.  Lower incisors are retruded-acrylic ground lingually ,labial bow active.  Upper posterior teeth guided mesially and lower posterior teeth guided distally- Class III correction.
  100. 100. Vertical dysplasia  Deep bite cases: The incisors are guided for intrusion and molars for extrusion .The labial bow active and contacts the incisal third.  Open Bite cases: The incisor area trimmed for extrusion and the molar area is intruded. The labial bow active and contacts the gingival third.
  101. 101. Limitations of Activator Treatment…
  102. 102.  appliance cannot be used by itself to correct crowding.  The appliance is not used in correction of Class I problems of crowded teeth caused by disharmony between tooth size and jaw size  Although the activator is effective in correction of overbite, it does not routinely achieve such correction through the intrusion of incisor teeth, but rather it permits the eruption teeth in the buccal segments.  Because the teeth in the buccal segments are permitted to follow their normal eruption paths and the incisor teeth are not permitted to erupt; the effect of intrusion is achieved without actually intruding the incisor teeth.
  103. 103.  It is more likely that successful activator treatment coincides with normal periods of active mandibular growth  Excessive LAFH and extreme vertical growth pattern.  Excessive procumbent lower incisors.  Nasal stenosis or chronic untreated allergy.  Non growing individuals.
  104. 104. Thought for the Day..!
  105. 105. Thank you For more details please visit