Principles of class iii treatment reformated /certified fixed orthodontic courses by Indian dental academy


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Principles of class iii treatment reformated /certified fixed orthodontic courses by Indian dental academy

  1. 1. Principles of class III treatment INDIAN DENTAL ACADEMY Leader in continuing dental education
  3. 3. features of true and pseudo class III True class III • Concave profile • a class III skeletal pattern, • No premature contacts • Forward path of closure • Gonial angle increased or decreased. • Retrusion of mandible is not possible Pseudo class III Straight / concave a class I skeletal pattern, Premature contacts present Deviated path of closure Normal gonial angle Retrusion of mandible is possible
  4. 4. Class III subdivision This is characterized by class I molar relation on one side and class III on the other side
  5. 5. Habitual occlusion Centric relation
  6. 6. Class III modifications of Martin Dewey • Type I: the upper and lower dental arches when viewed separately are in normal aligment . But when the arches are made to occlude the patient shows an edge to edge incisor aligment, suggestive of forwardly moved mandibular dental arch.  Type II:Type II: Mandibular incisors are crowded andMandibular incisors are crowded and are in lingual relation to the maxillary incisors.are in lingual relation to the maxillary incisors.  Type III:Type III: The maxillary incisors are crowded andThe maxillary incisors are crowded and are in cross bite in relation to the mandibularare in cross bite in relation to the mandibular anteriors.anteriors.
  7. 7.
  8. 8. CEPHALOMETRIC CLASSIFICATION OF CLASS III – Moyers 1. Class III malocclusions caused by dentoalveolar malrelationships 2. Class III malocclusions with a long mandibular base 3. Class III malocclusions with under developed maxilla
  9. 9. 4. Class III skeletal malocclusion with a combination of underdeveloped maxilla and prominent mandible (horizontal / vertical growth pattern) 5. Class III skeletal malocclusion with tooth guidance or pseudo forced bite.
  10. 10. ETIOLOGY OF CLASS IIIETIOLOGY OF CLASS III 1 Genetical determination 2 Functional factors and soft tissue influence 3 Occlusal forces due to abnormal eruption pattern 4 Environmental factors 5 other factors
  11. 11. True class IIITrue class III Pseudo class III Large mandible Retro positioned maxilla Small maxilla occlusal prematurities enlarged adenoids premature loss of deciduous molars Abnormal path of eruptionForwardly placed mandible Combination of the above
  12. 12. Initial Symptoms of Class III Malocclusion • Early signs of true, progressive mandibular prognathism occasionally can occur in infancy. • A protruded mandible with an anteriorly positioned tongue can be seen only in cases of very severe dysplasia before the eruption of the incisors. • In the first months of life a sequential development of the Class III condition may be observed.
  13. 13. This step-by-step progression is • 1. Eruption of the maxillary central incisors in a lingual relationship and the mandibular incisors in a forward position with no overjet • 2. Development of an incisal crossbite during the eruption of the lateral incisors into a normal relationship • 3. Full incisor crossbite some weeks later • 4. Flattening of the tongue as it drops away from palatal contact and postures forward, pressing against the lower incisors • 5. Habitual protraction of the mandible by the child into the protruded functional and morphologic relationship
  15. 15.
  16. 16. Management of pseudo-Class III malocclusion  Involves both permanent & deciduous dentition.  The optimum ages 6–9 years.  Reason to avoid early correction of pseudo-Class III in the deciduous dentition because of poor stability of correction. (cross bite may develop during the transitional dentition, pt lands up in further treatment )
  17. 17.  Some practitioners prefer to wait for the permanent maxillary incisors to erupt before initiating therapy due to the natural tendency of teeth to erupt in a lingual position during dental arch development.  Sometimes, functional deciduous anterior cross bites occasionally correct themselves spontaneously.
  18. 18. White – intervention of pseudo-Class III malocclusion in mixed dentition when maxillary and mandibular incisors have erupted allows the permanent teeth to erupt into a better position and improves the dental aesthetics. Advantages of treatment of pseudo-Class III malocclusion in the mixed dentition: prevents unfavorable growth of skeletal components (early treatment of anterior cross bite can help to minimize adaptations that are often seen in severe late adolescent malocclusion)
  19. 19. Prevents functional posterior cross bite and habits, ( bruxism develops from anterior or posterior interferences). Gaining space for eruption of canines (lack of space could be caused by retro-inclination of upper incisors frequently found in pseudo or Class III malocclusion) Avoids the risk of periodontal problems to mandibular incisors caused by the traumatic occlusion due to the cross bite.
  20. 20. • Equilibration • Acrylic inclined planes along the mandibular incisors • Maxillary labial bow along with mandibular inclined plane. • Bionator therapy
  21. 21. • Equilibration - • Systematic reshaping of the occlusal anatomy of teeth to minimize the role of occlusal disharmonies • In primary dentition – grind with bur • In mixed dentition – teeth should be moved with appliances to a position where it achieves a final proper occlusion
  22. 22. Indicated in pseudo class III with upper incisors tipped lingually causing anterior mandibular displacement on closure from postural rest to habitual occlusion.
  25. 25. FUNCTIONAL CLASS III RELATIONSHIP. • no skeletal Class III signs are present. • The mandible slides anteriorly into an edge-to-edge or crossbite relationship. • Usually the tooth guidance is in the canine region. • Careful equilibration of these teeth is needed to correct the problem.
  26. 26. • In other cases, • decreased intercanine distance - caused by chronic nasorespiratory problems; - low tongue posture are the morphology that results in tooth guidance. Rx-- expansion of the maxillary arch without canine equilibration is indicated.
  27. 27. So a functional Class III relationship may be a beginning sign of a true Class III malocclusion. Patients with such malocclusions need to" be followed continuously, and orthopedic guidance may be needed at any time.
  28. 28. CLASS III RELATIONSHIP WITH THE FAULT IN THE MANDIBLE • the mandibular basal measurement -large • S-N-B angle can be large. • Maxilla- usually normally developed Treatment objective Growth inhibition or redirection and posterior positioning of the mandible A chincap or a reverse (Class III) activator can be used to exert a retrusive force on the mandible
  29. 29. CLASS III RELATIONSHIP WITH THE FAULT IN THE MAXILLA • retrognathic maxilla or midface • orthognathic mandible • The tooth buds of the upper incisors are often rotated and crowded. Treatment in mild cases - with an activator or Fra'nkel appliance, in severe problems- extraoral orthopedic protractive force using a Delaire-type face mask is required.
  30. 30. • Kraus (1956), Fra'nkel (1967), and others recommended Loading the palatal area behind the upper incisors while relieving the labial muscle forces with lip pads, is often effective. • Eruption of the incisors before the maxillary incisors become locked behind the mandibular counterparts is advantageous.
  31. 31. • A combination of these two types of Class III malocclusions (retrusive maxilla and protrusive mandible) of course is possible and logically requires therapeutic control of both areas via maxillary protraction and mandibular retractive growth guidance.
  32. 32. Class III / reverse bionatorClass III / reverse bionator  to encourage development of maxilla.  construction bite- post most retruded position of mand.  allows a labial movement of maxillary incisors and restrictive influence on the mandible.
  34. 34. In Class III malocclusions with fault in the mandible in mixed dentition • treatment objectives - growth inhibition and posterior mandibular positioning • early mixed dentition, extraction of the lower deciduous canines and deciduous first molars can be performed to facilitate the correction of the incisal guidance. In some selected cases, enucleation of the lower first premolars - decreasing lower arch length and providing dental compensation for the skeletal problem as the six lower anterior teeth are retracted into the extraction sites. -Germectomy also limits alveolar growth.
  35. 35. • Rx class III in vertical growth pattern is more difficult than treatment with a horizontal pattern. • Achieving a good overbite is difficult with a vertical growth vector. Excessive anterior face height is evident; it compensates for the growth but usually is not enough. • In these cases a chincap or a low or high-pull headgear may be helpful to control posterior eruption, depending on the growth direction.
  36. 36. In Class III malocclusions in the mixed dentition with the fault in the maxilla, • promote growth and protract the maxillary complex. • Both horizontal and vertical growth should be encouraged because maxillary vertical deficiency enhances the apparent mandibular protrusion with its autorotation into an overdosed habitual occlusion. • An improvement in the midface concavity can be seen if treatment is performed during the eruption of the maxillary incisors. • The eruption can be channeled as desired by the guiding planes of the activator, with simultaneous relief) of labial muscle force provided by the lip pads at the depth of the vestibule. Simultaneously the mandible can be put under retrusive chincap force to reduce the sagittal discrepancy
  37. 37. • . An alternate approach • align the maxillary arch with a short period of direct-bonded attachments or active plates; the mid-face can be favorably influenced by the orthopedic protraction of a Delaire mask. • If the crowding in maxillary arch is too severe, extraction may be required in the maxillary arch. In such a case the lower first premolars also must be removed to allow proper dentitional adjustment. • fixed multiattachment therapy & possible orthognathic surgery may be the therapies of choice, depending on the severity of the problem and the age-linked expressivity.
  38. 38. JEAN DELAIRE(1960) of France had found that this approach involves applying forces on to the maxillary sutures while reciprocally pushing on the mandible and the forehead through the anchorage provided to the facial mask.
  39. 39. . Delaire mask
  40. 40. petit facial mask lateral view frontal view
  41. 41. COMPONENTS OF FACIAL MASK a. Facial mask b. Bonded maxillary expansion splint . c. Heavy elastics
  42. 42. a. Face mask  Extra oral device modified by petit A forehead pad and a chin pad connected by a heavy steel rod  A cross bow is attached to rod , to which elastics are attached. Brings a downward and forward traction on maxilla. Can be adjusted by adjusting screws.
  43. 43. b. Bonded maxillary splint  An acrylic splint for permanent and primary molars  Hook engaged in mesial aspect of splint in first deciduous molar region c. Elastics  Elastics attached to the hook and traction is applied
  44. 44. Effects 1. correction of CO-CR discrepancy, a shift in occlusal relation ship occurs immediately in pseudo class III 2. max protraction with 1-2 mm of forward movement is seen along with forward movement of dentition 3. lingual tipping of lower incisors in preexisting cross bites 4. redirection of mandibular growth in downward and backward direction which results in increase in lower anterior facial height. 5. Forward movement of maxilla and maxillary teeth specially in old pts.
  45. 45. Skeletal effects of maxillary protraction  Nanda – found that with the same line of force , different mid facial bones were displaced in different directions depending on the moment of force generated at sutures.  Jackson, Konich and Shapiro – found that anterior positioning of the maxillary complex is accompanied with a small amount of clockwise rotation during the treatment period.
  46. 46. Frankel III myofunctional applianceFrankel III myofunctional appliance Counteract the muscle forces acting on maxillary complex. Early mixed dentition and deciduous dentition. Mechanism of action: it shields the distracting forces of upper lip transmitted on to the maxilla by upper labial pads and are transmitted to the mandible by the loose fit of the appliance.
  47. 47. LIP PADS – eliminate the restrictive forces of the upper lips on the maxilla as well as they provide a stretching of the adjacent periosteum , stimulating bone apposition on the labial alveolar surface. The distracting forces of the upper lip are removed from the maxilla by the upper labial pads. The force of the upper lip is transmitted through the appliance to the mandible because of the close fit of the appliance to that arch
  48. 48. Occlusal view of FR III
  49. 49. Treatment effects- Skeletal and dental effects are produced Forward movement of maxillary skeletal and dental land marks Backward rotation of the mandible with an increase in the lower anterior facial height Proclination of the upper incisors and lingual tipping of lower incisors are seen.
  50. 50. CHIN CAP – mandibular prognathismmandibular prognathism • Oldest of all the treatments. • Chin cups have been used for Class III correction. • Design of a chin cup for Class' III patients directs the force posteriorly through the condyles. • To rotate the mandible upward, the line of force should be through the centroid of the roots of the lower arch.
  51. 51. Types- 1) Occipital pull chin cap- in mand prognathism 2) Vertical pull chin cap – in steep mand plane angle and excess lower ant facial height. Chin cup design To rotate the mandible closed, force is directed through the posterior teeth, not through the condyle.
  52. 52. Occipital pull chin cap – : in mild – moderate mand prognathism : it is successful if patients can bring incisors edge to edge : used in short lower ant facial ht ( increases the vertical dimension) : if vertical dimension should be increased the line of force should pass thro the condyles and below it .
  53. 53. Treatment in the permanent dentition • If Class III malocclusion is primarily dentoalveolar and not a true skeletal malrelationship-Rx is successful • The skeletal type of Class III malocclusion can be compensated by tooth removal and surgery.
  54. 54. CAMOUFLAGE TREATMENT Beyond the adolescent growth spurt to correct a skeletal problem teeth should be displaced relative to their supporting bone to compensate for the underlying jaw discrepacy. This is termed camouflage treatment.
  55. 55. The characteristics of a patient who would be a good candidate for camouflage treatment are: • Too old for successful growth modification • Mild skeletal Class III • Reasonably good alignment of teeth (so that the extraction spaces would be available for controlled anteroposterior displacement and not used to relieve crowding) • Good vertical facial proportions, neither extreme short face (skeletal deep bite) nor long face (skeletal open bite)
  56. 56. camouflage treatment is avoided in: • Moderate or severe Class III, and vertical skeletal discrepancies • Patients with severe crowding or protrusion of incisors, in whom the extraction spaces will be required to achieve proper alignment of the incisors • Patients with excellent remaining growth potential (in whom growth modification treatment should be used) or non-growing adults with more than mild discrepancies (in whom orthognathic surgery usually offers better long-term
  57. 57. The characteristics of a patient who would be treated best by surgically repositioning the jaws are: • Severe skeletal discrepancy or extremely severe dentoalveolar problem • Adult patient (little if any remaining growth), or younger patient with extremely severe or progressive deformity • Good general health status (mild, controlled systemic disease acceptable)
  59. 59. SURGICAL PROCEDURES: In case of, Maxillary deficiency- Le Fort I Osteotomy Mandibular excess- Saggital split osteotomy prominent chin- Reduction Genioplasty.
  60. 60. POST SUGICAL ORTHODONTICS Can be initiated 3 to 4 weeks after the release of immobilization. Stabilization arch wires are removed and replaced by working arch wires with light vertical forces till a good stable occlusion is achieved.
  61. 61. Thank you For more details please visit