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Tmj instrumentation /certified fixed orthodontic courses by Indian dental academy


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Tmj instrumentation /certified fixed orthodontic courses by Indian dental academy

  1. 1. TMJ INSTRUMENTATION INDIAN DENTAL ACADEMY Leader in continuing dental education
  3. 3. INTRODUCTION  SYNOVIAL JOINT  MOVEMENTS can be 1. In upper joint space - hinge 2. In lower joint space – hinge + gliding    Goals of orthodontic treatment harmony between occlusal function and TMJ. Occlusion and its role on TMJ health – DEBATABLE Ideal occlusal relationship should coincide with ideal condyle-fossa
  4. 4.  RETRUDED AXIS POSITION –     condyles articulate with the thinnest avascular portion of their respective disks anterior-superior position discernible when the mandible is directed superiorly and anteriorly and restricted to a purely rotary movement about a transverse horizontal axis. CENTRIC OCCLUSION   The occlusion of opposing teeth when the mandible is in centric relation. This may or may not coincide with the maximum intercuspation position.
  5. 5. • RETRUDED CONTACT POSITION - occlusal position when the first tooth contact occurs on the path of closure in the retruded axis position. • BENNETT ANGLE – angle at which the orbiting condyle moves inward during laterotrusive movement and is measured in relation to the horizontal plane. • OCCLUSAL INTERFERENCE – It is any tooth contact that inhibits the remaining occluding surfaces from achieving stable and harmonious contacts.
  6. 6. OPTIMAL FUNCTIONAL OCCLUSION 1. 2. 3. 4. 5. 6. 7. 8. Musculoskeletally stable position. Ideal condyle-fossa- disc relationship. Bilateral occlusal contacts in RCP. RCP =ICP or a slide of < than 1 mm Working side contact during laterotrusion. No contact on balancing side during laterotrusion. Full extent of jaw movement has to be recorded. check the end-of-therapy occlusion using mounted models.
  7. 7. NORMAL CONDYLE-DISC- FOSSA RELATIONSHIP ROTH- acceptable difference between CR and CO -1.00 mm AP, 1.00 mm in vertical plane and 0.5 mm in transverse plane.
  8. 8. SIGNS OF CR-CO DISCREPANCY        Occlusal wear. Excessive tooth mobility. Temporomandibular joint sounds. Limitation of opening or movement. Myofascial pain. Contracture of mandibular musculature, making manipulation difficult or impossible. Some types of tongue-thrust swallow.
  9. 9. MOUNTED VS HANDHELD CASTS  CLINICAL 1.Patients will not willingly bite in CR if that is not where the teeth fit best. 2. An accurate clinical assessment of occlusal interfacing, even in CR, is suspect if tooth mobility is present. 3. Border movements can be recorded. 4. Joint sounds can be heard. 5. Lingual perspective of teeth cannot be seen.
  10. 10. HAND-HELD CASTS 1. 2. 3. When unmounted casts are set on their trimmed distal borders, only the facial perspective of the static occlusion can be seen. If the casts are held in the hands without the wax bite, what is seen cannot be relied on because all three vertical restraints are exclusively dental. How the teeth interrelate when functioning cannot be assessed with hand-held casts. Lingual perspective can be seen.
  12. 12. MOUNTED MODELS 1. 2. 3. 4. Tooth mobility avoided by making impressions with soft materials to prevent deflection. once casts are mounted - uncompromised picture of the occlusal conditions can be observed. Mounted casts lead to better diagnosis, better results, and to fewer retention problems. How teeth interface in centric relation (CR) and when functioning can be seen facially and lingually without patient's avoidance mechanism (proprioception).
  13. 13. METHODS OF RECORDING MAXILLOMANDIBULAR RELATIONS        Thielmann (1939) – spiegelkinometer Sears (1952) – condyle migrator. Posselt (1957) – gnathothesiometer Buhner – Buhnergraph – for locating centric relation and verification of terminal hinge axis location. Long (1973) – leaf gauge – shims made of acetate or plastic Williamson (1980) – vericheck SLAVICEK (1988)- SAM articulator and MPI
  14. 14. VERICHECK by WILLIAMSON The Vericheck instrument will measure the variation from centric relation in three planes of space.
  15. 15. RECORDING CONDYLAR POSITION Facebow  Articulators  Mandibular Position Indicator(MPI)  Electronic MPI  Axiography  Computerised Axiography 
  16. 16. FACEBOW     First introduced by RICHMOND HAYES- articulating caliper Later modified by SNOW Serves to transfer 3-D relationship between Mx. Dental arch and starting point of mand. movement. Transverse hinge axis- passes thru both condyles and associated with rotation of mand in vertical direction – clinical relevance- orientation of the maxillary cast.  Types Arbitrary  kinematic 
  17. 17.   Primary use- mount maxillary cast accurately on the articulator Reference points1. Posterior- hinge axis  2. Anterior- arbitrary    Most semiadjustable articulators- rely on arbitrary hinge axis. If a discrepancy exists between the hinge axis and the articulator axis - premature contact will occur on the path of closure on the articulated model, not present clinically
  18. 18. Arbitrary facebow transfer     Anatomic average values used based on the work of SNOW Semiadjustable articulators rely on arbitrary hinge axis location. Line from tragus to outer canthus of eye 11-13 mm from the tragus of ear- arbitrary location. Kinematic face bow transfer   Required for fully adjustable articulators. Recorded by using a special bow attached to the mandible and is cemented to the teeth.
  19. 19. Facebow – SAM 2
  20. 20. ARTICULATORS     First described by MITCHELL & WILKIE in 1958 Articulator- instrument that represents the TMJ and jaws to which the maxillary and mandibular casts are attached. means of reproducing occlusal relationships outside the mouth. must be able to simulate an individual’s jaw movement mandibular movements are influenced by many soft tissue factors, hence impossible for jaw movements to be precisely reprodued.
  21. 21.  semiadjustable articulators provide an adequate representation of the true occlusion for orthodontic diagnosis.  Roth and Cordray - it is impossible to believe the clinical finding as a true representation of occlusion - occlusal interferences.  only by articulator mounting can the true occlusion be studied.
  22. 22. CLASSIFICATION OF ARTICULATORS SEMI-ADJUSTABLE NON-ADJUSTABLE five records all three records 1 or 2 records Face bow record Face bow record FULLY ADJUSTABLE Face bow record Centric relation record Centric relation record Centric relation record Protrusive record Protrusive record Lateral records Intercondylar distance record Protrusive record
  23. 23. Non adjustable articulators  average values are used to represent the inclination of the glenoid fossa and condyle fossa relationship.  cannot accurately reproduce an individual’s mandibular excursive movements.  only accurate position that can be used on a nonadjustable articulator is one specific oclusal contact position.
  24. 24. Advantages: 1. 2. 3. Inexpensive. Less time required to mount the casts. No procedures are required to mount casts. Disadvantages: 1. 2. Restorations cannot be properly planned. Additional time is required to adjust the restorations intraorally.
  25. 25. Semi adjustable articulators  can be modified by adjustments made in the condyle fossa portion of the instrument  Allows more variability in duplicating condylar movements.  It usually has 3 types of adjustments 1. 2. 3. Condylar inclination. Lateral translation movement or Bennett angle. Intercondylar distance.
  26. 26.  condylar inclination: angle at which the condyle descends. can be altered  Bennett angle: angle described by the orbiting condyle during laterotrusive movements. semiadjustable articulators allow for a Bennett angle movement only in a straight line.  Intercondylar distance: The distance between the rotational centers of the condyles.Three general settings - small, medium and large.
  27. 27. Records required 1. 2. 3. Facebow transfer. Centric relation interocclusal record. Eccentric interocclusal records Advantages: 1. 2. The adaptability to patient’s specific condylar movement. Accurately fitting restorations can be fabricated. Disadvantages: 1. 2. 3. Initially more time is required. More expensive than nonadjustable type. condylar path is in straight line, unlike the true condylar path, which follows a curved path.
  28. 28. Fully adjustable articulators     have a large range of adjustability in all three dimensions most complex types of articulators most sophisticated type for recording mandibular movements. adjustments that can be made are Condylar inclination. 2. Bennett angle. 3. Rotating condylar movement. 4. Intercondylar distance. 1.
  29. 29.  Condylar inclination:Angle during protrusive and laterotrusive movements can be adjusted. capable of recording curvature of patients condylar movements.  Bennett angle: both bennett angle and bennett shift can be recorded.  Rotating condylar movement:pathway of the rotating condyle duplicates that of the patient.  Intercondylar distance: can be adjusted in a fully adjustable articulator to match that in the patient more precisely.
  30. 30. Records required: 1. 2. 3. An exact hinge axis location. A pantographic recording. A centric relation interocclusal record. Advantages: 1. 2. Ability to duplicate mandibular movements precisely. Stable and anatomic interocclusal relatioship can be obtained. Disadvantages: 1. 2. Considerable amount of time is required. Highly expensive.
  31. 31. INDICATIONS FOR ARTICULATOR MOUNTED MODELS     When a significant discrepancy exists between RCP & ICP (> 2mm). Orthodontic cases with multiple missing teeth. Cases undergoing orthognathic procedures. Mounting of study models pre orthodontic treatment and pre debond in individuals with TMD is recommended.
  32. 32. USES OF ARTICULATORS IN ORTHODONTICS    For diagnosis and treatment planning. For finishing. In orthognathic surgical cases.
  33. 33. IN DIAGNOSIS AND TREATMENT PLANNING       Diagnosis carried out with teeth in ICP- misleading inappropriate treatment plan. small proportion of patients have a large discrepancy between RCP and ICP. Such large discrepancies are not easy to diagnose clinically. may be necessary to deprogram the neuromusculature. Articulated models reveal the AP relationship of maxilla and mandible more accurately. ease with the visualisation of static and functional interrelationships of the teeth.
  34. 34.  can be used to aid the clinician whether selective grinding can be undertaken.  sectioning of the teeth and repositioning them in wax - final results of orthodontics can be visualised.  orthodontic setup provides valuable information for treatment planning.  Patients with hypodontia and multiple missing teeth may not have a reproducible ICP. only reproducible relationship that can be recorded is RCP-requires articulator mounted models.
  35. 35. ARTICULATORS FOR FINISHING  Non working side contacts are harmful to the dentition - trigger bruxism, TMJ disorders or instability of tooth position. Hence these interferences have to be eliminated.
  36. 36. ARTICULATORS FOR ORTHOGNATHIC PLANNING  essential part of presurgical preparation  ramus osteotomies - seperation of tooth bearing parts of mandible from the condyle. no benefit in maintaining condyle tooth relationship during model surgery and hence an arbitrary mounting is sufficient.  maxillary surgery, autorotation of the mandible will be necessary - the condyle tooth relationship should be recorded as precisely as possible.
  37. 37. MANDIBULAR POSITION INDICATOR Dynamic and static positions of mandible determined by: 1. 2. 3. 4. 5. 6. neuromuscular system and proprioceptivity. morphology of hard and soft structures of the TMJ. The morphology of the occlusal surfaces of the teeth. Compromises necessitated by various skeletal patterns. Head posture and its relationship to the cervical spine. The limits of motion established by ligaments attached to the mandible.
  38. 38. MANDIBULAR POSITION INDICATOR  The M.P.I. quantifies differences between RCP & ICP.  used to perceive whether a clinically determined symptom or sign can be related to differences between the patient's RCP and ICP, if early signs of discopathy are present, and if a treatment plan to move the teeth will result in an occlusion in which RCP and ICP are compatible.
  39. 39. MOUNTING OF CASTS  Accurate impressions  Stone casts
  40. 40.  Base of casts – Split cast former
  41. 41. Anatomic facebow oriented to soft tissue porion and orbitale.
  42. 42. Face bow record transferred to articulator
  43. 43. Recording centric relation Mandible guided into retral position by the operator(guided by the thumb and forefinger at gnathion)
  44. 44. Roth power centric  Anterior segment- 3 thickness wax. Caninecanine.  Posterior segement – 2 thickness wax. Molar region.
  45. 45. Roth power centric technique
  46. 46. M.P.I PROCEDURE      Adhesive grid paper- on incisal table Upper member lowered to first contact Incisal pin lowered Grid mark – red marking Vertical height of pin noted.
  47. 47. maxillary cast is transferred to the M.P.I. M.P.I and upper part of the SAM 2 articulator are identical, except condylar housing are replaced with sliding blocks in the M.P.I
  48. 48.  Mounted maxillary cast is interdigitated with mandibular cast  Adhesive grids with X, Z coordinates are placed on the lateral sliding blocks of the M.P.I.
  49. 49.  Adhesive grid on black cubes of MPI  Mark position of condylar spheres with black articulating paper (hinge axis position)
  50. 50.  Incisal pin vertical reading – Delta H  Horizontal difference between RCP &ICP read at incisal table - Delta L  Dial gauge reading – Delta Y
  51. 51.  Cubes slid medially to perforate grid.  Point of perforation indicates hinge axis.
  52. 52. Results      Delta H = vertical increase or decrease read from the incisal pin. Delta L = protrusive or retrusive movement measured from tne incisal table (grid) Delta X = protrusive or retrusive. Indicates differences in horizontal condylar position. Delta Z = compression or distraction. Indicates differences in vertical condylar position. Delta Y = right or left transverse movement. Indicates differences in transverse condylar position.
  53. 53. ICP (black dot) below RCP (red dot) indicates distraction. ICP (black dot) above RCP (red dot) indicates compression.
  54. 54. ELECTRONIC MPI  displays data that are the same as those taken manually with the M.P.I. Standard records are designated numerically as the differences between: 1. RCP and the intercuspal position (ICP) 2. RCP and bilateral joint resilience (RES) 3. RCP and estimated therapeutic position (ETP) 4. RCP and ideal vertical position (IVP) 5. RCP and forced bite position (FBP) 6. ICP and a new ICP after full-mouth opening
  55. 55.
  56. 56. AXIOGRAPHY     Axiograph - diagnostic instrument- simulates condylar movement pathways. The procedure is called AXIOGRAPHY. The graphic output is called AXIOGRAM. Records movements in all 3 planes of space. Early detection of subclinical discopathies.
  57. 57.  Reference planehinge axis.  Normal joint The axiograph simultaneously records hinge-axis movements in all 3 planes.
  58. 58.  Facebow of axiograph attached to cranium.  Hinge-axis bow anchored to the mandible with functional occlusion clutch.
  59. 59. Tracing of hinge axis movement  Three dimensional recording as stylus is replaced by dial gauge.
  60. 60.  Deranged joint- location and repeatability of a reference position is impossible.  Difficulty to locate hinge axis may be due to 1. 2. 3. 4. 5. 6. Flattened condylar head. Inflammation Internal derangement. Loose ligaments. Structural asymmetries Muscle imbalance.
  61. 61.  Movements traced are 1. 2. 3. 4.  protrusion-retrusion, opening-closing, unguided mediotrusion-medioretrusion, right and then left; guided mediotrusion-medioretrusion, right and then left. Joint sounds – crepitation and clicking should be recorded.
  62. 62. Bennett movement   Mediolateral movement of the mandible measured along the Y axis. Bennett value altered by 1. Medially displaced meniscus 2. Luxation 3. Subluxation. 4. Reduction.
  63. 63. Resiliency test  Determines the ability to move the hinge-axis position superiorly anteriorly to a loaded position  Children -1mm of resiliency, young adult .5mm, and middle-aged or elderly patients .3mm.  No joint resiliency- results in deroundation - flattening of the condyle head. Resiliency below normal requires treatment with splints.
  64. 64. Joint resiliency test Upward pressure  Condyle displaced superiorly & anteriorly 
  65. 65. Interpretation of Axiograpic Tracings Sagittal movements  Coincide for first 1012mm  Bilaterally symmetrical  No Bennett movement. (0.2-0.3 mm acceptable)
  66. 66. Sagittal movements When movements do not coincide 1. 2. 3. Muscle limitation Differentiate between muscular and ligamentous limtation. Correlate with clinical findings.
  67. 67. Protrusion – retrusion tracings      Normally coincide in pattern and timing Position altered by loose ligaments. Asymmetry in timing seen due to in coordination of medial and lateral pterygoids. Limited movement seen in class II div II No transverse deviation of bennett movement – deviation indicates incipient discopathy.
  68. 68. Mediotrusion – Medioretrusion     principally a unilateral translation, with minimal vertical movement. The condyle head rotates minimally within the inferior concavity of meniscus. If tracings do not coincide - indicative of loose ligaments, subluxation, luxation, or reduction. Medially displaced meniscus restricts movement.
  69. 69. Opening/closing movements     Opening movement involves the rotational component of the mandible - is extremely important in diagnosing morphological changes in the head of the condyle. Comparisons between rotational and translatory movements are paramount to a proper diagnosis. Rotational movements- lower joint abnormalities Translatory movements- upper joint abnormalities.
  70. 70. Overrotation of mandible
  71. 71. Deroundation of condyle
  72. 72. Muscle distraction
  73. 73. Highly active temporalis
  74. 74. Loose joint
  75. 75. Functional distraction
  76. 76. COMPUTER AIDED AXIOGRAPHY   enhances the tracking of hinge-axis movements in all 3 planes along with timing of movement and accuracy. computer displays the condylar movement in real time.
  77. 77. Locating hinge axis     Located by having the patient rotate open, without translation, for at least 10mm- If the stilus is not on the hinge-axis position it will scribe an arc. uses this arc to form a circle and then calculates its center, which is the site of pure rotation— the true hinge-axis. Accuracy of location- 0.01mm Accuracy of manual method – 0.2 mm
  78. 78. Thank you For more details please visit