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Activator therapy /certified fixed orthodontic courses by Indian dental academy


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Activator therapy /certified fixed orthodontic courses by Indian dental academy

  1. 1. ACTIVATOR INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Contents • 1.Introduction • 2.Basic anatomy • 3.History of functional appliance • 4 Studies of functional appliance therapy • 5 Principles of functional appliance therapy • 6.Cephalometric diagnosis for functional appliance therapy • 7.History of activator • 8.Activator • 9.Mode of action of activator • 10.Force analysis in activator therapy
  3. 3. 11 .Construction bite 12. Fabrication and management of the activator 13. Trimming of the activator 14. Modifications of Activator 15.The Bionator—a Modified Activator. 16. The Bimler Appliance 17. Review of literature 18. conclusion
  4. 4. INTRODUCTION: T he 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 trasmit 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.
  5. 5. 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 used to correct Class II malocclusions.
  6. 6. MUSCLES INVOLVED IN MASTICATION • • • • Masseter Temporalis Medial pterygoid Lateral pterygoid
  7. 7. HISTORY OF FUNCTIONAL APPLIANCES • Four men out of the past who came forward with a fundamentally new approach to orthodontics • • • • Norman W. Kingsley Pierre Robbin, Alfred P. Rogers Viggo Andresen
  8. 8. HISTORY OF ACTIVATOR • 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.
  9. 9. •   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.
  10. 10. • Impressed by Kingsley's concepts and appliances, Andresen 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 working it a biomechanic retainer.
  11. 11. • Some years before Andresen started experimenting with his working retainer, • Robin had 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.
  12. 12. • Familiar with the work of Roux, who subscribed to the shaking-the-bonding-substance-of-bone hypothesis, the time Andresen and Haupl teamed up to write about their appliance, they called it an activator, be-cause of its ability to activate the muscle forces
  13. 13. • NEUROMUSCULAR RESPONSE The success of functional appliance therapy depends on the neuromuscular response. Children with neuromuscular diseases such as poliomyelitis and cerebral palsy
  14. 14. ACTIVATOR SYNONYMS :  - Biomechanic working retainer - Andersen appliance - Nocturnal airway patency appliance. - Norwegian appliance. - monobloc - kingsley or bite jumping appliance
  15. 15. • The first removable functional appliance, developed by V.Andresen.
  16. 16. • 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 .
  17. 17. appliances position the • These mandible forward, promoting a new mandibular postural position. • The reactive forces from the stretch of the muscles and soft tissues are transmitted to the maxillary dentition and through that, to the maxilla.
  18. 18. • The acrylic body of the Andresen activator covers part of the palate and the lingual aspect of the mandibular alveolar ridge. • 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.
  19. 19. EFFICACY OF THE ACTIVATOR • According to Andresen and Haupl (1955), the activator is effective in exploiting the interrelationship between function and changes in internal bone structure. • The activator induces musculoskeletal adaptation by introducing a new pattern of mandibular closure.
  20. 20. • Neuromuscular adaptation to the increased distance and changes in direction is the basic requirement for reeducating the orofacial musculature.
  21. 21. • The adaption in the functional pattern caused by the activator and also include and affect the condyles. • Condylar adaptation to anterior positioning of the mandible consists of growth in an upward and backward direction to maintain the integrity of TMJ structures.
  22. 22. • This adaptation is induced by a loose appliance. The construction bite does not open the mandible beyond postural rest position • Myotatic reflex activity is stimulated, causing isometric muscle contraction. This muscle force transmitted by the appliance moves the teeth. Thus the appliance works by kinetic energy.
  23. 23. • Although Andresens and Haupl's original concept and working hypothesis have been discussed and practiced for 55 years, they are still controversial; some authorities accept some or all of their ideas, whereas others completely reject them.
  24. 24. Classification of veiws • depending on the construction of the appliance, the activator can initiate myotatic reflex activity, induce isometric muscle contractions (sometimes also inducing isotonic contractions), or rely on the viscoelastic properties of the stretched soft tissues.
  25. 25. • According to the mode of action, two main principles apply. A third approach combines the two rationales.
  26. 26. • 1. According to the original AndresenHaupl concept, the forces generated in activator therapy are caused by muscle contractions and myotatic reflex activity. • A loose appliance stimulate the muscle and the moving appliance moves the teeth. • The muscles function with kinetic energy and intermittent forces are clinically significant.
  27. 27. • 2. According to the second working hypothesis, the appliance is squeezed between the jaws in a splinting action. • The appliance exerts forces that move the teeth in this rigid position. • The stretch reflex is activated, inherent tissue elasticity is operative, and strain occurs without functional movement.
  28. 28. • The appliance works using potential energy. • For this mode of action an overcompensation of the construction bite in the sagittal or vertical plane is necessary. • An efficient stretch action is achieved by overcompensation and the viscoelastic properties of the contiguous soft tissues.
  29. 29. 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.
  30. 30. • 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.
  31. 31. • 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
  32. 32. • 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. • In young people this induces a cell proliferation in the condyle and a growth response. • The activator can, to a limited degree control the upper growth vector, supplied by the sphenoccipital synchondrosis,which moves the maxillary base forward.
  33. 33. • If the mandible cannot be positioned anteriorly, maxillary growth can be inhibited and redirected. • activator also must assess and, if necessary, alter the vertical skeletal relationship. • Changing the maxillary base inclination can compensate for rotations of mandibular growth vectors. • A downward displacement of the maxillary base allows the maxilla to adapt to a vertical rotation of the mandible.
  34. 34. • If the rotation of the jaw bases during growth is unfavorable, activator therapy cannot be completed successfully. • If the activator is constructed with a vertical opening of the bite only or with minimal sagittal change, the effect is primarily on midfacial development in the subnasal area. Both vertical maxillary growth and eruption of the teeth are restricted.
  35. 35. • Woodside believes that a small vertical opening restricts only horizontal midfacial development, whereas a wide vertical opening achieves the restriction by downward displacement of the midface area.
  36. 36. • 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.
  37. 37. • The dentoalveolar effect of the activator is to control tooth eruption and alveolar bone apposition. • For this reason the activator is most effective if used in the early mixed dentition. • With proper trimming of the appliance, different movements can be performed and the eruption of the teeth can be guided.
  38. 38. FORCE ANALYSIS IN ACTIVATOR THERAPY • When the functional appliance activates the muscles various types of forces are created— • static, • dynamic, • rhythmic.
  39. 39. • Two principles are employed in the modern activator: • Force application —the source is usually muscular. • Force elimination —the dentition is shielded from normal & abnormal functional and tissue pressures by pads, shields, and wire configurations.
  40. 40. • 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. These artificially functioning forces be effective in all three planes:
  41. 41. • a. In the sagital 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. • A slight reciprocal force can be transmitted to the maxilla during this maneuver
  42. 42. • b.vertical plane the teeth and alveolar processes are either loaded with or relieved of normal forces. • If the construction bite is high, a greater strain is produced to the contiguous tissues. • If transmitted to maxilla these forces can inhibit growth increament and direction and influence the inclination of maxillarybase.
  43. 43. • c. In the transverse plane, forces also can be created with midline corrections. • 3.Various active elements (e.g., springs, screws) can be built into the activator to produce an active biomechanic type of force application. •
  44. 44. CONSTRUCTION BITE • Proper activator fabrication requires the determination and reproduction of the correct construction or working 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.
  45. 45. 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.
  46. 46. 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:
  47. 47. – Functional analysis. Before the construction bite is taken,a functional analysis is performed to obtain the following information: – 1. Precise registration of the postural rest position in natural head posture (because the vertical opening of the construction bite depends on this) – 2. Path of closure from postural rest to habital occlusion(any sagittal or transverse deviations are recorded)
  48. 48. • 3. Prematurities, point of initial contact, occlusal interferences, and resultant mandibular displacement, if any (some of these can be eliminated with the activator, but some require other therapeutic measures) • 4. Sounds such as clicking and crepitus in the TMJ (might indicate a functional abnormality or the need for some modification of appliance design)
  49. 49. • 5. Interocclusal clearance or freeway space (should be checked several times and the mean amount recorded) • 6. Respiration (with allergies or disturbed nasal respiration, the patient cannot wear a bulky appliance; in such cases an open activator or twin block may be used, or the respiratory abnormalities may be eliminated first)
  50. 50. 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. • Anterior positioning of this magnitude is contraindicated if any of the following pertain: • 1.The overjet is too large: • 2.Labial tipping of the maxillary incisors is severe:
  51. 51. • 3.An incisor (usually a lateral) has erupted markedly to the lingual: The mandible must be postured anteriorly to an eidge-to-edge relationship with the lingually malposed tooth; otherwise, labial movement of this tooth will be impossible. • 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.
  52. 52. • Opening the bite. Vertical considerations are as important as the sagittal determination and are intimately linked to it. Maintaining a proper horizontal-vertical relationship and determining the height of the bite are guided by the following principles: • 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.
  53. 53. • 3. If extensive vertical opening is needed, the mandible must not be anteriorly positioned. If the bite opening exceeds 6 mm, mandibular protraction must be very slight . Myotatic reflex activity of the muscles of mastication can then be observed, as can a stretching of the soft tissues. The vertical relationship, either deep bite or open bite,can be therapeutically affected by the activator.
  54. 54. • Disadvantages of a wide-open construction bite include the difficulty of wearing the appliance and adapting to the a new relationship. Muscle spasms often occur, and the appliance tends to fall out of the mouth. The high construction bite also makes lip seal difficult if not impossible. • The ultimate reestablishment of normal lip seal is esential in functional appliance therapy.
  55. 55. General rules for the construction bite. • The assessment of the construction bite determines the • kind of muscle stimulation, • frequency of mandibular movements, and • duration of effective forces.
  56. 56. • In a forward positioning of the mandible of 7 to 8 mm the vertical opening must be slight to moderate (2 to 4 mm). • 2. If the forward positioning is no more than 3 to 5 mm the vertical opening should be 4 to 6 mm. • 3. The activator can correct lower midline shifts or deviations only if actual lateral translation of the mandible itself exists. If the midline abnormality is caused by tooth migration, no asymmetric relationship exists between the mandible and maxilla. An attempt to correct this type of dental problem could lead to iatrogenic asymmetry. Functional crossbites in the functional analysis can be corrected by taking the proper construction bite.
  57. 57. • Execution of the Construction ' Bite Technique
  58. 58. • A construction bite prepared on casts may have the following disadvantages: • 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.
  59. 59. Technique for a Low Construction Bite with Markedly Forward Mandibular Positioning
  60. 60. • Technique for a High Construction Bite with Slightly Anterior Mandibular Positioning
  61. 61. • Technique for a Construction Bite without Forward Mandibular Positioning
  62. 62. • Construction Bite with Opening and Posterior Positioning of the Mandible
  63. 63. MANAGEMENT OF THE APPLIANCE • • • If the patient is wearing the activator without difficulty and fowllowing instructions, 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. Maxillary change is usually minimal at best, however. If the permanent teeth are erupting, reshaping also may be motion of the appliance in the mouth may change wire configurations and occasionally fatigues wires sufficiently to cause necessary.
  64. 64. • 3. Acrylic contact guide planes often must be resealed or recontoured 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. The guiding and stabilizing wires are activated by the patient's biting into the appliance.
  65. 65. • 6. In expansion treatment the jackscrews are normally activated by the patient at 2-week intervals. The clinician should check this activation for too-frequent or infrequent activation. Too much activation prevents the appliance from fitting properly. The activation interval may need to be changed.
  66. 66. MODIFICATIONS OF ACTIVATOR • Herren Shaye activator : Herren modified the activator in two ways : • 1. By overcompensating 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).
  67. 67. 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.
  68. 68. Wunderers modification • This is an activator modification that is mostly used in treatment of Class III malocclusion.
  69. 69. 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.
  70. 70. Hyperpropulsor Activator GEORGES GAUMOND, 1986 Jun JCO • The hyperpropulsor activator,developd from the monobloc of Robin, consists of a bimaxillary block of acrylic made with the bite open and the mandible in a forward position.
  71. 71. • The incisal edges of the upper and lower incisors should be separated 12-15mm, with the only limit to hyperpropulsion being the discomfort of the patient. Extraoral force is used with the appliance, which is worn only at night.
  72. 72. Indications: • The appliance is most useful in younger children when a sizable overjet raises fear of incisal fracture. • The appliance is also effective in Class II, division 1 cases when a small tooth-to-jaw size relationship would contraindicate extraction; in cases of missing upper bicuspids or molars, especially if there is already spontaneous space closure; and in cases of poor cooperation with fixed appliances. • The appliance can be used in cases of posterior rotation, since it does not alter the vertical dimension. • It also permits, to the extent of the individual's growth potential, a reduction of the discrepancy between the maxillary and mandibular bony arches— either by acting on the maxilla through varying the extraoral force, or by acting on the mandible through acrylic added as soon as the patient can propulse beyond the initial registration.
  73. 73. 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.
  74. 74. The Karwetzky modificaton: • 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 sagitally 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 sagital movement of the mandible
  75. 75.
  76. 76. 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.
  77. 77.
  78. 78. 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).
  79. 79.
  80. 80. 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 increase not supposed to the activity of the lateral pterygoidmuscle
  81. 81. 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 headstrap 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. 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.Accordingto 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.
  82. 82.
  83. 83. 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.
  84. 84.
  85. 85. 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.
  86. 86. NAPA
  87. 87.
  88. 88. Open Semiflexible activator • By Levrini .A (JCO 1996) • The OSA is a modified bionator that incorporates principles developed by Bimler, Klammt,Stockfisch, and Woodside. It is a composite myodynamic functional appliance, with a rigid frame of acrylic resin and stainless steel wires connected to elastomeric occlusal pads.
  89. 89.
  90. 90.
  91. 91.
  92. 92. Indications of activator : • • • • • • • • • • • • It is primarily used in actively growing individuals with favorable growth pattern. The maxillary and mandibular teeth should be well aligned. The mandibular incisors should be upright over the basal bone. The following are some of the indications forthe use of activator : 1. Class II, Division 1 malocclusion 2. Class II, Division 2 malocclusion 3. Class III malocclusion 4. Class I open bite malocclusion 5. Class I deep bite malocclusion 6. As a preliminary treatment before major fixed appliance therapy to improve skeletal jaw relations 7. For post-treatment retention 8. Children with lack of vertical development in lower facial height.
  93. 93. 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 nongrowing individuals.
  94. 94. 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
  95. 95. 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.
  96. 96. Activators As Retainers [JCO 1980 Aug(529 - 545)]: • Many severe Class II cases are treated with fixed appliances to completion before jaw growth is completed. • The posttreatment growth pattern occasionally causes the case to relapse back into a Class II relationship. The activator is very useful for retaining these cases, especially where there was a deep bite involved. A strong relapse tendency will also require directional headgear
  97. 97. Studies of Functional Appliance Therapy • • • • • • • Woodside Altuna Shapera Sessle Sectakof & Yamin Organ Voudouris
  98. 98. The studies summarized in this chapter have led to the following conclusions, which may influence the clinician's approach to functional appliance treatment: • 1. Removable functional appliances used part time do not routinely create clinically useful increases in mandibular length. • 2. Redirection of maxillary growth direction may occur with either a large or moderate vertical opening of the construction bite. • 3. Successful redirection of maxillary growth direction is always followed by recovery toward the normal path of growth direction. However, a net restriction in midface position occurs. • 5. Both the function regulator and bionator activator create similarly increased amounts of LPM activity at appliance insertion. • 6. The insertion and progressive activation of a functipnal appliance produce a decrease in the resting and functional activity of the muscles of mastication. 7. Chronic condylar unloading produces a rapid down ward and forward relocation of the glenoid fossa; this relocation •
  99. 99. The Bionator—a Modified Activator • • -Developed by Balter -Termed by Kantorowicz • APPLIANCE PHILOSOPHY • Kantorowicz's assessment of the bionator is essentially correct in two ways. (1) The bionator is, in fact, considerably less bulky than the activator. It lacks the part covering the anterior section of the palate, which is contiguous to the tongue. Children are therefore immediately able to speak normally, though the appliance fits loosely in the mouth. Thus, it is possible to require that the bionator be worn day and night except at meals. It is feasible for wear during school. An important feature of the bionator is its freedom of movement in the oral cavity. It would be totally incorrect and detrimental to fix it by any device on either the maxillary or mandibular teeth. • •
  100. 100. • (2) To Balters, the essential factor is the tongue. To quote him, "The equilibrium between tongue and cheeks, especially between the tongue and the lips in the height, breadth and depth in in an oral space of maximum size and optimal limits, providing functional space for the tongue, is essential for the natural health of the dental arches and their relation to each other. Every disturbance will deform the dentition and during growth that may be impeded too. The tongue is the essential factor for the development of the dentition. It is the center of the reflex activity in the oral cavity."
  101. 101. TREATMENT OBJECTIVES • According to Balters, the essential points for treatment are to accomplish lip closure and bring the back of the tongue into contact with the soft palate; • • • to enlarge the oral space and to train its function; to bring the incisors into an edge to edge relationship—like Begg, he feels that this is a natural bodily orientation; • by virtue of the preceding, to achieve an elongation of the mandible, which, in turn, will enlarge the oral space and make the improved tongue position possible; • to achieve an improved relationship of the jaws, tongue and the dentition, as well as the surrounding soft tissues, as a result.
  102. 102. • The treatment of Class II, division 1 malocclusions in the'-mixed dentition using the standard bionator is indicated under the following conditions: • 1. The dental arches are well aligned originally. • 2. The mandible is in a posterior position (i.e., functional retrusion). • 3. The skeletal discrepancy is not too severe. • 4. A labial tipping of the upper incisors is evident.
  103. 103. • The bionator is not indicated if the following is true: • 1. The Class II relationship is caused by maxillary prognathism. • 2. A vertical growth pattern is present. • 3. Labial tipping of the lower incisors is evident. Anterior posturing of the mandible with simultaneous uprighting of the lower incisors cannot be performed with the bionator.
  104. 104. BIONATOR TYPES • Standard Appliance. • Open-Bite Appliance. • Reversed bionator.
  105. 105. BIONATOR AND TEMPOROMANDIBULAR JOINT CASES • The main purpose is to prevent the riding of the condyle over the posterior edge of the disk, which causes the clicking. • By checking clinically, first in habitual occlusion and then in a forward postured mandible, the operator can determine how far forward the mandible must be brought to eliminate the clicking on the opening maneuver. The clicking usually disappears in these cases when the mandible is opened in the forward posture. This means that the condyle no longer rides over the posterior disk margin, onto the retrodiscal pad.
  106. 106. REVIEW OF LITERATURE • 1. MAD II FOR CORRECTION OF CLASS II DIV 1 MALOCCLUSION Am J Orthod 1993 M.Darelinder,A.Jean Pierre Joho. • SAMARIUM COBALT Magnets are incorporated on the buccal aspects of the upper and lower appliances. •
  107. 107. MAD can be used as • -for correction of mandibular lateral deviation (MAD I) • -for class II malocclusions (MAD II) • -for class III malocclusion (MAD III) • -for open bite cases (MAD IV)
  108. 108. Tongue function during activator treatment. A cephalometric and dynamometric study by Johan Ahlgren EJO1(1979)251-257 • The results seem to verify Andresen's hypothesis that tongue activity is stimulated by activators but they do not support his view that wearing an activator would result in permanent hypertrophy of the tongue muscles.
  109. 109. How effective is the combined activator-headgear treatment? By Olav Bondevik (EJO 1991) • The frequency and possible causes of failure and success with the combination activator-headgear as the sole appliance was analysed retrospectively in 32 girls and 46 boys. The subjects comprised all the patients who started treatment with this combination in the postgraduate courses in 1972-82 at the Orthodontic Department of the University of Oslo, and where fixed appliances were not included in the initial treatment plan. Only 14 subjects completed the treatment with entirely satisfactory results according to strict criteria set for an acceptable standard. Among the most co-operative patients less than 50 per cent ended with entirely satisfactory results, and no one with decreasing or poor co-operation had a satisfactory result. Neither sex, treatment time, nor ossification of the ulnar sesamoid bone seemed to influence the results significantly.
  110. 110. Treatment needs followingActivatorheadgear therapy By Iav Bondevik, ( Angle orthod 1995) • The purpose of this study was to analyze the types and prevalence of malocclusions that remain to be corrected after a period combined activator-headgear treatment. Study models of all patients who started treatment with an activator-headgear appliance in the graduate orthodontic clinic at the University of Oslo between 1972 and 1982 were screened. • Results show that the most frequently remaining problems following activator-headgear treatment were overbite, overjet and the presence of interdental spaces. Correction of the Class II skeletal and dental relationship was achieved in the majority of the cases. The only predictor for success was age at the time of treatment.
  111. 111. Combination Headgear-Activator - DR. HERMAN VAN BEEK JCO Volume 1984 Mar(185 - 189): • • • • • • • • • • • Clinical Aspects of Headgear-Activator Treatment The headgear-activator has the following modes of action: 1. Intrusion and retraction of upper front teeth 2. Distalization of upper molars 3. Maxilla retraction 4. Mandibular growth stimulation, especially in the brachyfacial group 5. Opening of the facial axis in the brachyfacial group 6. Maintenance of the facial axis in the dolichofacial group 7. Minor, if any, tilting of lower incisors 8. Stopping lower incisor eruption 9. Stopping the descent of the palate
  112. 112. Activator treatment - Vargervik and Harvold • Response to activator treatment in Class II malocclusions • A clinical study was designed to disclose the effects of activator treatment in the correction of Class II malocclusions. The rationale for the use of the activator appliance was based on the premise that correction of distocclusion can be achieved by • (1) inhibition of forward growth of the maxilla, • (2) inhibition of mesial migration of maxillary teeth, • (3) inhibition of maxillary alveolar height increase and extrusion of mandibular molars, • (4) increased growth of the mandible, • (5) anterior relocation of the glenoid fossa, • (6) mesial movement of mandibular teeth, • (7) combinations of these effects.
  113. 113. • It was therefore concluded that, in addition to the statistically significant changes, smaller changes occurred in several areas without being consistent enough or of a large enough magnitude to become statistically significant in the analyses of mean values. Comparison of group averages may mask treatment effects that significantly contribute to the correction of malocclusions in individual
  114. 114. 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 sample consisted of thirty Class II, Division 1 malocclusion cases treated successfully with activators during an average time period of 32 months. Before- and aftertreatment head films in centric occlusion were analyzed. The occlusal line (OL) and occlusal line perpendicular (OLp) through sella were used for reference. Linear measurements were performed parallel to OL..
  115. 115. • • • • • 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. (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
  116. 116. Effects of Activator Treatment on Class II, Division 1 Malocclusion (JCO) Aug 1989 - DR. CHANG, DR. KAI-MING WU, DR. KUN-CHEE CHEN, • • • • • • This study was undertaken to evaluate the effects of activator treatment on a group of Class II, division 1 patients with skeletal mandibular retrusion. Materials and Methods: Nine boy and six girl patients from the Orthodontic Department, National Taiwan University Hospital, were selected as the treatment group. All were Chinese, and they ranged in age from 7.2 to 11.9 years, with a mean of 9.5 years. All were treated exclusively with activators. The untreated control group consisted of 21 boys and 14 girls, with similar Class II, division 1 malocclusions, selected from the growth studies of the School of Dentistry, National Taiwan University. All were Chinese, and the mean age was 9.6 years. Patients were asked to wear the appliances about 14 hours per day, but no effort was made to measure cooperation. Pretreatment cephalograms of the two groups were compared statistically to confirm that there were no significant differences in craniofacial morphology.
  117. 117. • Activator treatment in this study was successful in girls and boys from age 7 to 12. Children from age 7 to 12 are highly responsive to praise and positive reinforcement and therefore tend to be cooperative. Early functional appliance treatment can correct any abnormal muscular habits that might influence later facial development and form.
  118. 118. Temporal muscle activity during the first year of Class II, Division 1 malocclusion treatment with an activator (1991 Apr) Am J Orthod Bengt Ingerval and Urs Thüer, • 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 effect on muscle activity was compared with that in a similar group of children being treated with a headgear and with that in a control group receiving orthodontic treatment for Class I malocclusion.
  119. 119. • 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. 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.
  120. 120. Functional treatment of condylar fractures in adult patients E. K. Basdra,A. Stellzig, Drmeddent, . 1998 Jun Am J Orthod • 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.
  121. 121. • 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. 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.
  122. 122. Skeletal profile changes related to two patterns of activator effects - Luder Volume 1982 May Am J Orthod • A longitudinal cephalometric study was carried out on twelve boys and thirteen girls who initially exhibited Class II, Division 1 malocclusion and who were treated exclusively with activators. Twenty-four boys and fifteen girls, corresponding with the experimental subjects with respect to initial age and observation period, were selected as controls.
  123. 123. • • • • The aim of the investigation was to examine cephalometric profile changes associated with two patterns of effects of activator treatment detected previously. The findings demonstrate that the two types of reaction bring about similar corrections of both apical base discrepancy and dental Class II relationship but clearly differ in their effects on the skeletal profile. Whereas the first type of reaction results in an improvement in mandibular retrognathism, a marked rotation of the occlusal plane, and good vertical control of the upper and lower dental arches, the second type is distinguished by a significant reduction of maxillary prognathism, downward and backward rotation of the mandible, and forward tipping of the lower incisors. Additional evidence presented further suggests that the two patterns of effects are due to differences in the construction bites of the appliances. According to this hypothesis, a great interocclusal height of an activator would lead to the first and a low construction bite to the second type of reaction.
  124. 124. Orthodontic forces exerted by activators with varying construction bite heights Takuji Noro, Kazuo Tanne, and Mamoru Sakuda, AJO-DO1994 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. Fifteen adolescent patients with Class II and Class III malocclusions, (30 subjects) were used. Four types of activators were made for each patient with construction bites taken at incisal edge clearances of 2, 4, 6, and 8 mm vertically. The magnitude of forces generated by passive tension of soft tissues increased significantly (p < 0.01) from approximately in the Class II group and also increased in the Class III group with varying construction bite heights from 2 to 8 mm. Higher construction bites also significantly changed (p < 0.01) the direction of forces by passive tension from vertical to posterior and from vertical to anterior in relation to the reference plane in the Class II and Class III groups, respectively.
  125. 125. • 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
  126. 126. Predicting functional appliance treatment outcome in Class II malocclusion– Susi Barton, and Paul A. • 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 overjet of up to 11 mm, an increased overbite, active facial growth, and good cooperation. (Am J Orthod Dentofac Orthop 1997;)
  127. 127. CONCLUSION Catch them young Watch them grow
  128. 128. Thank you Leader in continuing dental education