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  1. 1. A Seminar on ACTIVATOR
  2. 2. The term "functional appliance" refers to a variety of removable appliances designed to alter the arrangement of various muscle groups that influence the function and position of the mandible in order to transmit forces to the dentition and the basal bone. Typically these muscular forces are generated by altering the mandibular position sagittally and vertically, resulting in orthodontic and orthopedic changes. INTRODUCTION:
  3. 3. Functional appliances have been used since the 1930s. Despite this relatively long history, there continues to be much controversy relating to their use, method of action, and effectiveness. Although there are a number of functional appliances used by clinicians, the activator is used to correct Class II malocclusions.
  4. 4. In 1880, Kingsley introduced the term and concept of "jumping the bite" for patients with mandibular retrusion. He inserted a vulcanite palatal plate consisting of an anterior incline that guided the mandible to a forward position when the patient closed on it. This maneuver corrected the sagittal relationship without tipping the lower incisors forward. HISTORY OF ACTIVATOR:
  5. 5.  Vorbissplatte was a modified Kingsley plate. Hotz used the appliance in cases of deep bite retrognathism when overbite was likely to cause a functional retrusion deep bite retrognathism, and the lower incisors were lingually inclined by hyperactivity of the mentalis muscle and lower lip. History:
  6. 6. Robin in 1902had created an appliance quite similar in its objectives. The monobloc, as he called it (because it was a single block of vulcanite), positioned the mandible forward in patients with glossoptosis and severe mandibular retrognathism who risked occluding their airways with their tongues. Robin noted that forward mandibular posture reduced this hazard and also led to significant improvement in the jaw relationship. The problem, usually associated with cleft palate, became known as the Pierre Robin syndrome. HISTORY:
  7. 7. Impressed by Kingsley's concepts and appliances, Viggow Andresen in 1908 developed a mobile, loose fitting appliance modification that transferred functioning muscle stimuli to the jaws, teeth, and supporting tissues. The progenitor of the appliance was a modified Kingsley plate that Andresen used as a retainer over summer vacation for his daughter after he removed fixed appliances used to correct a distocclusion. Seeing the continued improvement with this retainer, he called it a biomechanic working retainer. HISTORY:
  8. 8. Familiar with the work of Roux, who subscribed to the shaking-the-bonding-substance-of-bone hypothesis, the time Andresen and Haupl in 1955 teamed up to write about their appliance, they called it an Activator, because of its ability to activate the muscle forces HISTORY:
  9. 9. - Biomechanic working retainer - Andersen appliance - Nocturnal airway patency appliance. - Norwegian appliance. - Monobloc - kingsley or bite jumping appliance SYNONYMS:
  10. 10. NOMENCLATURE: The first removable functional appliance, developed by V.Andresen. Historically, the term "activator" was introduced to describe the "activation of mandibular growth," to which the achieved correction of a Class II malocclusion was attributed The acrylic body of the Andresen activator covers part of the palate and the lingual aspect of the mandibular alveolar ridge.
  11. 11. A labial bow fits anterior to the maxillary incisors and carries U- loops for adjustment. On the palatal aspects of the maxillary incisors, the acrylic is relieved to allow their retraction
  12. 12.
  13. 13. I. ANDRESEN & HAUPL CONCEPT According to Andresen & Haupl, the bite is not opened beyond the postural rest position (i.e. no more than 4mms) Forward positioning of mandible induces Myotactic reflex actively and Isometric muscle contraction. These muscle contraction forces Stimulate the LPM & retro- are transmitted by the appliance discalpad thus bring about to move the teeth. Bone remodeling & condylar adaptation. Thus activator rely mainly on the muscle activity during biting & swallowing & thus works by using KINETIC ENERGY.
  14. 14. MYOTACTIC REFLEX ACTIVITY: Lateral pterygoid muscle insertion Myotactic reflex activity in the muscle
  15. 15. CRITICISM ABOUT ANDRESEN & HAUPL CONCEPT Activator is mainly a night time wear appliance. During sleep the frequency of biting & Swallowing decreases and also the freeway space is almost double what it is when the patient is awake. This reduces the myotactic reflex activity & muscle contraction. So some authors argue that the efficiency of the activator is questionable.
  16. 16. II. HEREN, HARVOLD & WOODSIDE CONCEPT Bite is opened approximately 12-15mm beyond the postural rest position It induces stretching of soft tissues & the viscoelastic pull of the soft tissues are responsible for the appliance action. The power to produce alveolar remodeling is obtained from inherent elasticity of muscle, tendinous tissues & skin. Thus the appliance works by POTENTIAL ENERGY rather than kinetic energy (i.e. Myotactic reflex activity). III. The third concept is a combination of above 2.
  17. 17.
  18. 18. SKELETAL AND DENTOALVEOLAR EFFECTS OF THE ACTIVATOR: 1.Any skeletal effect from the activator depends on the growth potential. Two divergent growth vectors propel the jaw bases in an anterior direction a. The sphenoccipital synchondrosis moves the cranial base and nasomaxillary complex up & forward. b. The condyle translates the mandible in a downward and forward direction. The activator is most effective in controlling the lower vector or the downward and forward growth of the mandible.
  19. 19. Two divergent growth vectors
  20. 20. Johnston (1976) attributes this response to "unloading the condyle."  Only the upward and backward growth of the condyle is capable of moving the mandible anteriorly  As the research by Petrovic has shown, the LPM plays a decisive role in this growth.  Forward posturing of the condyle activates the superior head of the LPM  The activator can, to a limited degree control the upper growth vector, supplied by the sphenoccipital synchondrosis, which moves the maxillary base forward 2. The dentoalveolar efficiency of the activator helps achieve, a primary treatment objective. Teeth and bones fill in the space between the two divergent growth vectors.
  21. 21. Static – Permanent & vary in magnitude and direction Dynamic – Interrupted, appear simultaneously with movements of body and head; higher magnitude Rhythmic – associated with Respiration and circulation, amplitude varies with pulse Efficacy of activator during sleep depends frequency of the movements kind of construction bite alteration of interocclusal space Muscle tone Restlessness FORCE ANALYSIS IN ACTIVATOR THERAPY:
  22. 22. Force application - Usually muscular source Force elimination – dentition is shielded from normal and abnormal functional & tissue pressures
  23. 23. The types of force employed in activator therapy may be categorized as follows: 1. The growth potential, including the eruption and migration of teeth, produces natural forces. These can be guided promoted, and inhibited by the activator. 2. Muscle contractions and stretching of the soft tissues initiate force when the mandible is relocated from its position by the appliance. The activator stimulates and transforms the contractions. Whereas forces may be functional (muscular) in origin, their activation is artificial.
  24. 24. These artificially functioning forces be effective in all three planes: Sagittal plane: the mandible is propelled down and forward, so that muscle force is delivered to the condyle and a strain is produced in the condylar region. Vertical plane: The and alveolar process are either loaded or relieved of normal forces. If transmitted to maxilla these forces can inhibit growth and direction and influence the inclination of maxillary base Transverse plane: forces also can be created with midline corrections.
  25. 25. CONSTRUCTION BITE: The purpose of this mandibular manipulation is to relocate the jaw in the direction of treatment objectives. This creates artificial functional forces and allows assessment of the appliance's mode of action. Before taking the construction bite, the clinician must prepare by making a detailed study of the plaster casts, cephalometric and panoral head films, and the patient's functional pattern. Diagnostic Preparation: Creating an "instant correction"—moving the mandible forward into an anterior more normal sagittal relationship—may help motivate patients with Class II malocclusions.
  26. 26. Study model analysis: Before constructing the activator, the clinician must consider the following factors, based on the cast analysis: 1. First permanent molar relationship in habitual occlusion 2. Nature of the midline discrepancy, if any: 3. Symmetry of the dental arches: 4. Curve of Spee: 5. Crowding and any dental discrepancies:
  27. 27. Functional analysis. 1. Precise registration of the postural rest position in natural head posture 2. Path of closure from postural rest to habitual occlusion 3. Pre-maturities, point of initial contact, occlusal interferences, and resultant mandibular displacement 4. Sounds such as clicking and crepitus in the TMJ 5. Interocclusal clearance or freeway space 6. Respiration
  28. 28. Cephalometric analysis: Enables clinicians to identify the craniofacial morphogenetic pattern direction of growth Differentiation between position and size of jaw bases Morphologic peculiarities Axial inclination & position of the maxillary and mandibular incisors
  29. 29. TREATMENT PLANNING : The extent of anterior positioning for Class II malocclusion and posterior positioning for Class III malocclusions should be determined. Anterior positioning of the mandible. The usual intermaxillary relationship for the average Class II problem is end-to-end incisal. However, it should not exceed 7 to 8 mm, or three quarters of the mesiodistal dimension of the first permanent molar, in most instances. 1.The overjet is too large 2.Labial tipping of the maxillary incisors is severe: 3.An incisor (usually a lateral) has erupted markedly to the lingual: The mandible must be postured anteriorly to an edge-to-edge relationship with the lingually malposed tooth; otherwise, labial movement of this tooth will be impossible.
  30. 30. Eschler (1952) termed the condition a pathologic construction bite. As with severely proclined upper incisors, use of a short prefunctional appliance to improve alignment of lingually malposed teeth is advisable before starting activator treatment, thereby eliminating the need for the pathologic construction bite.
  31. 31. Opening the bite. Vertical considerations are as important as the sagittal determination and are intimately linked to it 1. The mandible must be dislocated from the postural resting position in at least one direction—sagittally or vertically. This dislocation is essential to activate the associated musculature and induce a strain in the tissues. 2.If the magnitude of the forward position is great (7 or 8 mm), the vertical opening should be minimal so as not to overstretch the muscles. This type of construction bite produces an increased force component in the sagittal plane, allowing a forward positioning of the mandible. 3. If extensive vertical opening is needed, the mandible must not be anteriorly positioned.
  32. 32. Disadvantages of a wide-open construction bite Difficulty of wearing the appliance and adapting to the a new Relationship Muscle spasms often occur appliance tends to fall out of the mouth. The high construction bite also makes lip seal difficult if not impossible
  33. 33. Vertical force component during opening of mandible Opening below rest position Sagittal force arising during anterior positioning
  34. 34. In a forward position of 7 – 8 mm the opening must be slight If forward position id not more than 3 – 5 mm the vertical opening should be 4 – 6 mm. If there is midline shift due to translation of mandible then it can be corrected GENERAL RULES FOR CONSTRUCTION BITE:
  35. 35. EXECUTION OF CONSTRUCTION BITE:  Horse shoe shaped wax rim is made in the proper arch form; should be 2-3mm thicker than the planned construction bite for guiding the mandible. Wax is placed is placed in lower for treatment of class II and in the upper for treatment of class III  Make the patient sit upright in the relaxed posture, guide the mandible into desired position without exerting force  Wax is placed in mouth after the operator is sure the patient can replicate  Edge to edge incisal relation is maintained  Midline is observed for coincidence  Wax bite is carefully removed
  36. 36. Wax placed over the cast Casts mounted on wax after obtaining bite registration
  37. 37. • It may not fit. • Asymmetric biting may have occurred on it. • The patient may not be really comfortable and may be disturbed more frequently during sleep. • The likelihood of unwanted lower incisor procumbency may be greater, because the appliance exerts undue stress on these teeth. Why Construction Bite Cannot be taken in Casts ?
  38. 38. MINIMAL VERTICAL OPENING : Commonly the bite is registered with the mandible in a slightly protruded position of 3mm, whereas the vertical bite is registered within the limits of patients freeway space. This increases the frequency of the reflex contractions in the muscle of mastication. When the mandible is moved mesially to engage the appliance the elevator muscles are activated. Thus Myotactic reflex is produced.
  39. 39. VOLITIONAL CONTROL: The neural pathway for the Volitional control of the masticatory muscles is explained as follows. The propioceptive fibers the PDL, muscles and TMJ ascend via the trigeminal nerve to the brain stem. The cell body is in the Mesencephalic nucleus. from there the tract descends to the masticatory nucleus on the ipsilateral side and synapses with the lower motor neurons. This carries motor impulses to the masticatory muscles via the third division of trigeminal nerve. The voluntary control of the muscle arises from the pyramidal cells of Betz in the cortex and descends via the upper motor neurons.
  41. 41. MODERATE VERTICAL OPENING: The mandible is protruded 3mm and the vertical bite is registered at 4mm beyond the rest position of the mandible. This activates the myotactic reflex and this increases the frequency of the swallowing and biting during the first few days of therapy. This is maintained by the force through increased active action of stretched muscle. This is needed when the appliance is worn mostly in the night and the rest position is altered during sleep. The extreme opening insures that the reflex will act when the musculature is more relaxed while sleeping. Since the activator does not permit muscle shortening the contractions are isometric than isotonic. Hence the muscle fiber develop more tension which is sustained during the periods of contraction.
  42. 42. MYOTACTIC REFLEX: It is the reflex action of skeletal muscle contraction. The stimuli is the stretch of the muscle which causes the contraction of stretched muscle. Muscle stretch receptors are proprioceptive muscle endings called muscle spindles. These are located within the muscle and contain 2-15 intrafusal fibers. The long slender ones are striated and contractile but the center or nuclear bag part is non contractile. The impulses arising from the spindles are conducted by the Group IA sensory fibers. They synapse with the motor neurons called Alfa efferent that supply extra fusal fibers. the myotactic or the stretch reflex is therefore a Monosynaptic reflex arc.
  44. 44. Construction Bite with Opening and Posterior Positioning of the Mandible 1) Used in class III cases 2) Prognosis is good for Pseudo class III
  45. 45. FABRICATION OF ACTIVATOR: Preparation of wire elements: the labial bow are the principal elements. Consists of a middle horizontal section and two vertical loops made of 0.9 mm for active and 0.8 mm for passive labial bow.
  46. 46. Fabrication of Acrylic portion: This consists of upper and lower and the inter occlusal parts. In a ‘v’ activator the flanges are higher than the ‘H’ activator due to enhanced retention required in ‘V’ activator. The flanges in the upper part are 8-12mm high in the gingival area covering the alveolar crest while the palate is free. The Acrylic plate is thin so it does not encroach the activity. To increase the rigidity palatal bar may be given which is 1.2mm thick. The lower acrylic plate is 5-10mm wide or 10-15mm in some cases.
  47. 47.
  48. 48. The stimulation of the functional activity of the peri- oral musculature with loose appliances to guide the movement and eruption of selected teeth can best be achieved by grinding away areas of acrylic that contact the teeth. Principles of 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 pf acrylic that contact the teeth. The acrylic surface that transmit the force and contact the teeth are called guiding planes
  49. 49. EVALUVATING ACTIVATOR TRIMMING: Evaluation with explorer Undercut surface in acrylic; And after trimming Shadow test for Trimming
  50. 50. TRIMMING THE ACTIVATOR FOR 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
  51. 51. 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 Molars: Done by loading the lingual surface of these teeth above the area of greatest convexity in maxilla and below this area for mandible. Indicated in deep bite cases
  52. 52. SELECTIVE TRIMMING OF THE ACTIVATOR: During selective trimming either the upper or the lower molar is extruded. The path of eruption must be considered
  53. 53. TRIMMING THE ACTIVATOR FOR SAGITTAL CONTROL: Can be achieved through PROTRUSION / RETRUSION of Incisors MESIAL / DISTAL movement of Molars Protrusion or retrusion is possible through Acrylic guide planes Labial bow Active Passive Position of Labial bow Gingival – Extrusion, Decreases Tipping Incisal – Inhibit extrusion, increase
  54. 54. In class III activator lip pads are used instead of a labial bow
  55. 55. PROTRUSION OF INCISSORS: Incisors can be protruded by loading their lingual surface and screening lip strain by passive labial bow. 1) Entire lingual surface loaded 2) Incisal third of lingual surface is loaded.
  56. 56. Protrusion by means of Auxiliary elements Protrusion springs Wooden pegs Guttapercha
  57. 57. Retrusion of Incisors: Acrylic is trimmed from the back of incisor Active Labial bow is incorporated
  58. 58. MOVEMENT OF POSTERIORS IN SAGITAL PLANE: Distalisation: the Guiding planes are loaded in the mesio lingual surfaces. Indicated in class II non extraction cases. Additional elements such as stabilizing wires or active open springs can be used.
  59. 59. Mesial movement: Can be achieved by loading the disto - lingual surfaces. Indicated for the upper arch in class III cases.
  60. 60. 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.
  61. 61. MANAGEMENT OF THE APPLIANCE: Checkup appointments should be scheduled every 6 weeks. During these office visits the clinician should maintain rapport with the patient, reinforce motivation, and perform the following procedures 1. All guide planes that have been ground and all areas in contact with the teeth should be observed for shiny surfaces that indicate whether the appliance is being worn correctly and is working properly. 2. Reshaping of acrylic guide areas may be required after initial trimming to improve function; it also may be needed during the course of treatment to ensure continued tooth movement (particularly in the upper arch) if retrusion or distalization is desired.
  62. 62. 3. Acrylic contact guide planes often must be resealed or recon toured to maintain the proper functional activation on the desired teeth by adding self-curing soft acrylic in a thin layer. Clinical examination of the acrylic inclined planes for shiny spots helps determine the amount of sealing to be done. 4. The labial bows and any additional wire elements must be checked for action and possible deformation. The active bow should touch the teeth. The passive bow should position away from the teeth but remain in contact with the soft tissues. 5. Lip pads should be checked for irritation in the sulcus area 6. Jack screws are activated every 2 weeks.
  63. 63. Finished appliance. Note deep extension of flanges.
  64. 64.
  65. 65. Herren Shaye activator: Herren modified the activator in two ways : 1. By over-compensating the ventral position of the mandible in the construction wax bite. 2. By seating the appliance firmly against the maxillary dental arch by means of clasps (arrowhead, triangular or Jackson's).
  66. 66. The Bow activator of A.M Schwarz The bow activator is a horizontally split activator having a maxillary portion and a mandibular portion connected together by an elastic bow. This kind of modification allows step wise sagittal advancement of the mandible by adjustment of the bow.
  67. 67. Wunderers modification: This is an activator modification that is mostly used in treatment of Class III malocclusion
  68. 68. Reduced activator or cybernator of Shmuth : This modification of the activator is proposed by Professor G.P.F. Schmuth. This appliance resembles a bionator with the acrylic portion of the activator reduced from the maxillary anterior area leaving a small flange of acrylic on the palatal slopes. The two halves may be connected by an omega shaped palatal wire similar to bionator.
  69. 69. The Karwetzky modification: This consists of maxillary and mandibular plates joined by a 'U' bow in the region of the first permanent molar. Type I: This is used in the treatment of Class II, Division 1. In this modification, the larger lower leg is placed posteriorly. Thus when the two arms of the U bow are squeezed the lower plate moves sagittally forwards Type II : This is used for the treatment of Class III malocclusion. In this appliance the larger lower leg is placed anteriorly. Thus when the U bow is squeezed the mandibular plate moves distally. Type III: They are used in bringing about asymmetric advancements of the mandible. The U bow is attached anteriorly on one side and posteriorly on the other side to allow asymmetric sagittal movement of the mandible
  70. 70.
  71. 71. Bimler appliance (Bite former, Bimler stimulator) A modification of the activator by H.P. Bimler. There are three main kinds of Bimler appliance: type A for patients with Class II Division 1 malocclusions, type B for those with Class II Division 2 and type C for patients with a Class III malocclusion.
  72. 72. Cut out or Palate free activator: This is a modification proposed by Metzelder to combine the advantages of bionator and the Andresen's activator. The mandibular portion of the appliance resembles an activator while the maxillary portion has acrylic covering only the palatal aspect of the buccal teeth and a small part of the adjoining gingiva. The palate thus remains free of acrylic thereby making the appliance more convenient for patients to wear the appliance for longer hours. Due to the greater amount of wearing time, success should be greater with the palate free activator.
  73. 73. Elastic open activator A modification of the activator developed by G. Klammt. The appliance has reduced acrylic bulk, facilitating increased appliance wear. The acrylic is replaced by wires which increase the flexibility of the appliance. The flexible design allows isotonic muscular contractions (in contrast to rigid appliances, which only allow isometric contractions).
  74. 74. Herren activator (L.S.U. activator): A modification of the activator developed by P. Herren (also known as the Louisiana State University modification of the same appliance). It is essentially an activator made to a construction bite that positions the mandible forward and downward to a significant degree. According to P. Herren, the wearing of this appliance is not supposed to increase the activity of the lateral pterygoidmuscle
  75. 75. PROPULSOR: Conceived by Muhlemann and refined by Hotz. Features with both the Monobloc and a simple oral screen. Advantage over other activator is the ability to cover and effect changes in the alveolar process. Useful in cases of maxillary dentoalveolar protrusion. No wire elements, needs frequent reactivation or modification with soft acrylic.
  76. 76. Lehman appliance (Lehman activator) A combination activator-headgear appliance developed by R.Lehman. It consists of a maxillary acrylic plate that carries two rigidly fixed outer bows and a mandibular lingual shield. The acrylic plate covers the palate and it extends over the occlusal and incisal surfaces of the maxillary teeth, up to the occlusal third of their buccal and labial surfaces. Selective expansion of the maxillary arch is possible by appropriately activating the two transverse expansion screws (one anterior and one posterior) that are embedded in the plate. Occipital traction is applied through a head strap attached on the outer bows, which are fixed at the anterior aspect of the appliance. The mandibular lingual shield is connected to the maxillary plate by means of two heavy S-shaped wires.
  77. 77. Unlike many activator type appliances which are constructed with the mandible in a protruded position, this appliance is made from a bite registration taken in centric occlusion. According to R.Lehman, the S-shaped wires are activated by approximately 2 mm every 4 to 6 weeks, to achieve a gradual advancement of the mandible
  78. 78. Teuscher-Stockli activator/headgear combination appliance A modified activator used in combination with a high-pull headgear. The appliance was introduced by U.M. Teuscher and P.W. Stockli as a means to avoid the detrimental profile effects of cervical traction when treating Class II malocclusions in growing individuals. Buccal headgear tubes are incorporated in the interocclusal acrylic at the level of the maxillary second premolar or first molar
  79. 79. Patient with Teuscher-Stockli appliance with headgear
  80. 80. Nocturnal airway patency appliance: By Peter T George (JCO)1987 NAPA was designed to keep the airway open during sleep by Posturing the tongue more anteriorly. inhibiting wide jaw opening. assuring adequate air intake through the mouth when ever nasal obstruction exists. The mandible was postured forward to advance the tongue relative to the posterior pharyngeal wall. Because the genioglossus originates at the inner surface of the mandibular symphysis and inserts into the tongue, the mandibular protrusion brings the tongue forwards.
  81. 81. Indications of activator : The following are some of the indications for the use ofThe following are some of the indications for the use of activator :activator :  1. Class II, Division 1 malocclusion1. Class II, Division 1 malocclusion  2. Class II, Division 2 malocclusion2. Class II, Division 2 malocclusion  3. Class III malocclusion3. Class III malocclusion  4. Class I open bite malocclusion4. Class I open bite malocclusion  5. Class I deep bite malocclusion5. Class I deep bite malocclusion  6. As a preliminary treatment before major fixed6. As a preliminary treatment before major fixed appliance therapy to improve skeletal jaw relationsappliance therapy to improve skeletal jaw relations  7. For post-treatment retention7. For post-treatment retention  8. Children with lack of vertical development in lower facial8. Children with lack of vertical development in lower facial height.height.
  82. 82. Contra-indications of activator therapy 1. The appliance is not used in correction of Class I problems of crowded teeth caused by disharmony between tooth size and jaw size, 2. The appliance is contraindicated in children with excess lower facial height and extreme vertical mandibular growth. 3. The appliance is not used in children whose lower incisors are severely procumbent. 4. The appliance cannot be used in children with nasal stenosis caused by structural problems within the nose or chronic untreated allergy. 5. The appliance has limited application in non-growing individuals.
  83. 83. Advantages of activator therapy 1. It uses existing growth of the jaws. 2. During treatment the patient experiences minimal oral hygiene problems. 3 .The intervals between appointments is long. 4. The appointments are usually short due to need for minimal adjustments. 5. Due to the above reasons they are more economical
  84. 84. Disadvantages of activator therapy 1. Requires very good patient cooperation. 2. The activator cannot produce a precise detailing and finishing of the occlusion. Thus post-treatment fixed appliance therapy maybe needed for detailing of the occlusion. 3. It may produce moderate mandibular rotation (anteriorly downwards). Thus activators are not used in cases of excessive lower face height.
  85. 85.
  86. 86. Tongue function during activatorTongue function during activator treatment.treatment. A cephalometric and dynamometric study byA cephalometric and dynamometric study by Johan AhlgrenJohan Ahlgren EJO (1979) 251-257EJO (1979) 251-257 The results seem to verify Andresen'sThe results seem to verify Andresen's hypothesis that tongue activity is stimulated byhypothesis that tongue activity is stimulated by activators but they do not support his view thatactivators but they do not support his view that wearing an activator would result in permanentwearing an activator would result in permanent hypertrophy of the tongue muscles.hypertrophy of the tongue muscles.
  87. 87. How effective is the combined activator-headgearHow effective is the combined activator-headgear treatment?treatment? By Olav BondevikBy Olav Bondevik (EJO 1991)(EJO 1991) The frequency and possible causes of failure andThe frequency and possible causes of failure and success with the combination activator-headgear as thesuccess with the combination activator-headgear as the sole appliance was analyzed retrospectively in 32 girls andsole appliance was analyzed retrospectively in 32 girls and 46 boys. The subjects comprised all the patients who46 boys. The subjects comprised all the patients who started treatment with this combination in thestarted treatment with this combination in the postgraduate courses in 1972-82 at the Orthodonticpostgraduate courses in 1972-82 at the Orthodontic Department of the University of Oslo, and where fixedDepartment of the University of Oslo, and where fixed appliances were not included in the initial treatment plan.appliances were not included in the initial treatment plan. Only 14 subjects completed the treatment with entirelyOnly 14 subjects completed the treatment with entirely satisfactory results according to strict criteria set for ansatisfactory results according to strict criteria set for an acceptable standard. Among the most co-operativeacceptable standard. Among the most co-operative patients less than 50 per cent ended with entirelypatients less than 50 per cent ended with entirely satisfactory results, and no one with decreasing or poorsatisfactory results, and no one with decreasing or poor co-operation had a satisfactory had a satisfactory result.. .. .
  88. 88. Neither sex, treatment time, nor ossification of the ulnarNeither sex, treatment time, nor ossification of the ulnar sesamoid bone seemed to influence the results significantlysesamoid bone seemed to influence the results significantly
  89. 89. Treatment needs following Activator-headgearTreatment needs following Activator-headgear therapytherapy By Lav Bondevik, ( Angle orthod 1995)By Lav Bondevik, ( Angle orthod 1995)  The purpose of this study was to analyze the types andThe purpose of this study was to analyze the types and prevalence of malocclusions that remain to be correctedprevalence of malocclusions that remain to be corrected after a period combined activator-headgear treatment.after a period combined activator-headgear treatment. Study models of all patients who started treatment with anStudy models of all patients who started treatment with an activator-headgear appliance in the graduate orthodonticactivator-headgear appliance in the graduate orthodontic clinic at the University of Oslo between 1972 and 1982 wereclinic at the University of Oslo between 1972 and 1982 were screened.screened.  Results show that the most frequently remaining problemsResults show that the most frequently remaining problems following activator-headgear treatment were overbite,following activator-headgear treatment were overbite, overjet and the presence of interdental spaces. Correctionoverjet and the presence of interdental spaces. Correction of the Class II skeletal and dental relationship wasof the Class II skeletal and dental relationship was achieved in the majority of the cases. The only predictorachieved in the majority of the cases. The only predictor for success was age at the time of treatment.for success was age at the time of treatment.
  90. 90. Combination Headgear-ActivatorCombination Headgear-Activator DR. HERMAN VAN BEEKDR. HERMAN VAN BEEK JCO Volume 1984 Mar(185 - 189):JCO Volume 1984 Mar(185 - 189): Clinical Aspects of Headgear-Activator TreatmentClinical Aspects of Headgear-Activator Treatment The headgear-activator has the following modes of action:The headgear-activator has the following modes of action:  1. Intrusion and retraction of upper front teeth1. Intrusion and retraction of upper front teeth  2. Distalization of upper molars2. Distalization of upper molars  3. Maxilla retraction3. Maxilla retraction  4. Mandibular growth stimulation, especially in the4. Mandibular growth stimulation, especially in the brachyfacial groupbrachyfacial group  5. Opening of the facial axis in the brachyfacial group5. Opening of the facial axis in the brachyfacial group  6. Maintenance of the facial axis in the dolichofacial group6. Maintenance of the facial axis in the dolichofacial group  7. Minor, if any, tilting of lower incisors7. Minor, if any, tilting of lower incisors  8. Stopping lower incisor eruption8. Stopping lower incisor eruption  9. Stopping the descent of the palate9. Stopping the descent of the palate
  91. 91. Activator treatmentActivator treatment Vargervik and HarvoldVargervik and Harvold Response to activator treatment in Class II malocclusions.Response to activator treatment in Class II malocclusions. A clinical study was designed to disclose the effects ofA clinical study was designed to disclose the effects of activator treatment in the correction of Class II malocclusions.activator treatment in the correction of Class II malocclusions. The rationale for the use of the activator appliance was basedThe rationale for the use of the activator appliance was based on the premise that correction of distocclusion can beon the premise that correction of distocclusion can be achieved byachieved by  (1) inhibition of forward growth of the maxilla,(1) inhibition of forward growth of the maxilla,  (2) inhibition of mesial migration of maxillary teeth,(2) inhibition of mesial migration of maxillary teeth,  (3) inhibition of maxillary alveolar height increase and(3) inhibition of maxillary alveolar height increase and extrusion of mandibular molars,extrusion of mandibular molars,  (4) increased growth of the mandible,(4) increased growth of the mandible,  (5) anterior relocation of the glenoid fossa,(5) anterior relocation of the glenoid fossa,  (6) mesial movement of mandibular teeth,(6) mesial movement of mandibular teeth,  (7) combinations of these effects.(7) combinations of these effects.
  92. 92. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment Hans Pancherz, (Am J Orthod) 1984 The purpose of this investigation was to evaluate cephalometrically the mechanism of anteroposterior occlusal changes in activator treatment. The following results were found: (1) The improvement in occlusal relationships in the molar and incisor segments was about equally a result of skeletal and dental changes. (2) Overjet correction averaging 5.0 mm was a result of 2.4 mm more mandibular growth than maxillary growth, a 2.5 mm distal movement of the maxillary incisors, and a 0.1 mm mesial movement of the mandibular incisors.
  93. 93. (3) Class II molar correction averaging 5.1 mm was a result of 2.4 mm more mandibular growth than maxillary growth, a 0.4 mm distal movement of the maxillary molars, and a 2.3 mm mesial movement of the mandibular molars. (4) When the findings were compared with longitudinal records of persons with normal occlusion (Bolton standards), activator treatment seemed to inhibit maxillary growth, move the maxillary incisors and molars distally, and move the mandibular incisors and molars mesially. Mandibular growth appeared not to be affected by activator treatment
  94. 94. Effects of Activator Treatment on Class II, DivisionEffects of Activator Treatment on Class II, Division 1 Malocclusion1 Malocclusion DR. CHANG, DR. KAI-MING WU, DR. KUN-CHEE CHEN,DR. CHANG, DR. KAI-MING WU, DR. KUN-CHEE CHEN, (JCO) Aug 1989(JCO) Aug 1989 This study was undertaken to evaluate the effects of activatorThis study was undertaken to evaluate the effects of activator treatment on a group of Class II, division 1 patients with skeletaltreatment on a group of Class II, division 1 patients with skeletal mandibular retrusion.mandibular retrusion. Activator treatment in this study was successful in girls andActivator treatment in this study was successful in girls and boys from age 7 to 12. Children from age 7 to 12 are highlyboys from age 7 to 12. Children from age 7 to 12 are highly responsive to praise and positive reinforcement andresponsive to praise and positive reinforcement and therefore tend to be cooperative.therefore tend to be cooperative. Early functionalEarly functional appliance treatment can correct any abnormal muscularappliance treatment can correct any abnormal muscular habits that might influence later facial development andhabits that might influence later facial development and form.form.
  95. 95. Temporal muscle activity during the first year of Class II, Division 1 malocclusion treatment with an activator Bengt Ingerval and Urs Thüer (1991 Apr) Am J Orthod The activity of the anterior and posterior temporal muscles in response to treatment with a splint type of activator was studied in children with distal occlusion. The activity in the rest position was constant during the 1-year period of observation. During maximal bite the activity of the posterior temporal muscle decreased significantly in the group with headgear and the control group and in a subgroup of children with large protrusions in the construction bite who had been treated with activators. This decrease was considered to be an effect of occlusal instability brought about by the treatment.
  96. 96. There was no evidence of a decrease in the postural (rest) activity of the posterior temporal muscle, although such a decrease has been described as a sign of forward displacement of the mandible during treatment with a functional appliance.
  97. 97. Functional treatment of condylar fractures in adult patients E. K. Basdra,A. Stellzig, Drmeddent 1998 Jun A J O Functional treatment of condylar fractures in adult patients usually follows the closed reduction / maxillomandibular fixation approach. Some of the problems arising when functional appliances (i.e., activator) are used have been identified and presented here, especially in patients where fractured parts are dispositioned/dislocated. They conclude that activators are not the best means of treating condylar fractures with displacements/dislocations in adult patients. Therefore patients who after the removal of the intermaxillary fixation show good occlusal relationships should be only treated with the use of intermaxillary elastics. Patients exhibiting anterior or lateral open bites after intermaxillary fixation should be treated with biteplates (half or posterior bilateral), combined with vertical elastics, to reestablish the initial occlusal relations
  98. 98. A small group of patients with condylar fractures treated by the above functional concept has been shown. They showed good response and reported no complaints or discomfort 1 year later. The occlusion recovered to the initial relationship and no selective grinding was necessary after treatment. This approach seems promising in the treatment of condylar fractures in adult patients.
  99. 99. Orthodontic forces exerted by activators with varying construction bite heights Takuji Noro, Kazuo Tanne, and Mamoru Sakuda, A J O 1994 Feb The present study was conducted to investigate the nature of forces induced with activators by measuring strains, electromyogram (EMG) and electroencephalogram (EEG) during a 2-hour sleep period. Duration of forces generated by passive tension was most significantly longer than that of active contraction of the jaw closing muscles, irrespective of the construction bite heights. It is concluded that passive tension, derived from viscoelasticity of soft tissues, plays a more important role in inducing changes than phasic stretch reflex during jaw orthopedic therapy with activators
  100. 100. Predicting functional appliance treatment outcome in Class II malocclusion Susi Barton, and Paul A (A J O 1997) Selecting cases suitable for treatment with a functional appliance remains a problem as much of the relevant literature is anecdotal. There are also design and methodologic differences between the available studies, and most studies are limited to the Andresen type of appliance. The literature suggests that functional appliances are most successful in cases with an over jet of up to 11 mm, an increased overbite, active facial growth, and good cooperation
  101. 101. CONCLUSION Catch them young Watch them grow
  102. 102.