Mandibular Movenets Bocher

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Mandibular Movenets Bocher

  1. 3. Components of the temporomandibular joint <ul><li>A, articular eminence </li></ul><ul><li>C, condyle; </li></ul><ul><li>D, articular disc </li></ul><ul><li>E, external auditory meatus </li></ul><ul><li>L, lateral pterygoid muscle </li></ul><ul><li>R, retrodiscal tissue </li></ul>
  2. 4. Masticatory system as a functional unit <ul><li>Jaws </li></ul><ul><li>Teeth </li></ul><ul><li>Temporomandibular joints (tmjs) </li></ul><ul><li>Associated ligaments </li></ul><ul><li>Muscles of mastication </li></ul><ul><li>Tongue </li></ul><ul><li>Cheeks </li></ul><ul><li>Lips </li></ul><ul><li>Sensory motor innervation (and vasculature) </li></ul>
  3. 5. In the edentulous patient <ul><li>Lost </li></ul><ul><ul><li>Teeth </li></ul></ul><ul><ul><li>Periodontal ligament nerves </li></ul></ul><ul><li>Tongue and other structures </li></ul><ul><li>Functional anatomy </li></ul><ul><li>Control and limits of jaw and joint motion </li></ul><ul><li>Relationships </li></ul><ul><li>Control of the lips </li></ul><ul><li>Physiological environment </li></ul>
  4. 6. Ideal occlusion <ul><li>That are harmonious with the existing tmjs and masticator) 1 muscles </li></ul><ul><li>Stable occlusal contacts </li></ul><ul><li>Vertical dimension of occlusion </li></ul>
  5. 7. Complexity of mandibular movements <ul><li>Many different mandibular movements occur during </li></ul><ul><ul><li>Mastication </li></ul></ul><ul><ul><li>Speech </li></ul></ul><ul><ul><li>Swallowing </li></ul></ul><ul><ul><li>Respiration </li></ul></ul><ul><ul><li>Facial expression </li></ul></ul><ul><ul><li>Parafunctional movements </li></ul></ul><ul><ul><ul><li>Bruxism </li></ul></ul></ul><ul><ul><ul><li>Clenching </li></ul></ul></ul>
  6. 8. Knowledgeable of mandibular movements <ul><li>To understand various aspects of occlusion </li></ul><ul><li>To arrange artificial teeth </li></ul><ul><li>To select and adjust recording devices and articulators </li></ul>
  7. 9. Factors that regulate jaw motion <ul><li>The direction of the movement </li></ul><ul><ul><li>Neuromuscular system </li></ul></ul><ul><li>Limited by the movement of </li></ul><ul><ul><li>The two condyles </li></ul></ul><ul><ul><li>And the guiding influences of the contacting teeth </li></ul></ul><ul><li>The condyles and teeth modify mandibular movements initiated by the neuromuscular system </li></ul>
  8. 10. Influence of opposing tooth contacts <ul><li>The manner in which the teeth occlude is related </li></ul><ul><ul><li>Occlusal surfaces of the teeth </li></ul></ul><ul><ul><li>Muscles. </li></ul></ul><ul><ul><li>Tmjs </li></ul></ul><ul><ul><li>Neurophysiological components </li></ul></ul><ul><ul><ul><li>Including the patient's mental well-being </li></ul></ul></ul><ul><li>Occlusal surfaces of the teeth should meet </li></ul><ul><ul><li>Evenly on both sides. </li></ul></ul><ul><ul><li>Mandible is not deflected its normal path of closure </li></ul></ul><ul><ul><li>Arc the dentures displaced from the residual ridges </li></ul></ul>
  9. 11. When mandibular movements are made <ul><li>With the opposing teeth of complete dentures in contact </li></ul><ul><ul><li>The inclined planes of the teeth should pass over one another smoothly </li></ul></ul><ul><li>Not disrupt the influences of the condylar guidance posteriorly and the incisal guidance anteriorly. </li></ul>
  10. 13. All mandibular motion is either ROTATION or TRANSLATION <ul><li>Rotational movements </li></ul><ul><ul><li>In the lower compartment of the TMJ </li></ul></ul><ul><ul><li>Between the superior surface of the condyles and the inferior surface of the articular disk. </li></ul></ul><ul><li>Translatory, or gliding, movements of the mandible </li></ul><ul><ul><li>Take place in the upper compartment of the TMJ </li></ul></ul><ul><ul><li>Between the superior surface of the articular disk as it moves with the condyles and the inferior surface of the glenoid fossa. </li></ul></ul>
  11. 14. In a healthy joint <ul><li>The condyle is in a superoanterior position in the fossa with the articular disc interposed when the teeth are in maximum intercuspation </li></ul>
  12. 15. In a healthy joint <ul><li>In the initial stage of opening, the condyle rotates in position, with the disc remaining stationary </li></ul>
  13. 16. In a healthy joint <ul><li>In maximum opening, the condyle translates forward, with the disc still interposed </li></ul>
  14. 17. Muscular involvement in jaw motion <ul><li>Increased activity during </li></ul><ul><ul><li>Any jaw movement. </li></ul></ul><ul><ul><li>Movement of the mandible </li></ul></ul><ul><ul><li>Fixation on a given position </li></ul></ul><ul><ul><li>Stabilization </li></ul></ul>
  15. 18. Neuromuscular regulation of mandibular motion <ul><li>Mastication is a programmed event </li></ul><ul><ul><li>In a &quot;chewing center&quot; </li></ul></ul><ul><ul><li>Located within the brain stem </li></ul></ul><ul><ul><ul><li>Probably in the reticular formation of the pons </li></ul></ul></ul><ul><li>Conscious effort </li></ul><ul><ul><li>Not required for the continuation of chewing </li></ul></ul><ul><ul><li>Either induce or terminate chewing </li></ul></ul><ul><li>Sensory impulses </li></ul><ul><ul><li>From the orofacial region </li></ul></ul><ul><ul><li>Modify the basic cyclic pattern of the chewing center to achieve optimal function </li></ul></ul>
  16. 19. Peripheral influences Jaw reflexes
  17. 20. Motion regulation <ul><li>The impulses initiated at the subconscious level can produce involuntary movements or modify voluntary movements </li></ul><ul><li>Impulses from the subconscious level, including the reticular activation system, also regulate muscle tone , which plays a primary role in the physiological rest position of the mandible </li></ul>
  18. 22. Envelop of motion
  19. 25. The Envelope of Motion <ul><li>limits of possible motion and certain mandibular reference positions </li></ul>
  20. 28. Envelope of motion (mandibular border movement area) in the sagittal plane. <ul><li>CO, Centric occlusion; </li></ul><ul><li>CR, centric relation; </li></ul><ul><li>MHO, maximum hinge-opening position </li></ul><ul><li>MO, point of maximum opening of the jaws </li></ul><ul><li>P, most protruded position of the mandible with the teeth in contact </li></ul><ul><li>Rest, postural rest position </li></ul>
  21. 31. Envelope of motion (mandibular border movements) in the frontal plane <ul><li>CO, Centric occlusion </li></ul><ul><li>MO, point of maximum opening of the jaws </li></ul><ul><li>Rest, postural rest position. </li></ul>
  22. 32. Postural rest position of the mandible hypotheses <ul><li>Active mechanism </li></ul><ul><ul><li>This position is assumed only when the muscles that close the jaws and those that open the jaws are in a state of minimal contraction to maintain the posture of the mandible. </li></ul></ul><ul><li>Passive mechanism </li></ul><ul><ul><li>Tolds that the elastic elements of the jaw musculature, and not only muscle activity, balance the influence of gravity. </li></ul></ul>
  23. 33. The current consensus is that the physiological rest position <ul><li>Actively determined. </li></ul><ul><li>Usually 2 to 4 mm below the maximum intercuspation position </li></ul><ul><li>EMG rest position is usually several millimeters lower than in the clinical rest position. </li></ul><ul><ul><li>Up to an interocclusal distance of about 10 mm </li></ul></ul><ul><li>More accurate to refer to a &quot;range of posture&quot; rather than to a single rest position. </li></ul>
  24. 34. Rest position of the mandible <ul><li>Relative stable for reasonable lengths of time. </li></ul><ul><li>Factors can influence the postural rest position </li></ul><ul><ul><li>Wear </li></ul></ul><ul><ul><li>Loss of teeth </li></ul></ul><ul><ul><li>Aging </li></ul></ul><ul><ul><li>General health factors </li></ul></ul><ul><ul><li>Position of the head </li></ul></ul><ul><ul><ul><li>Head is reclined </li></ul></ul></ul><ul><ul><ul><ul><li>The distance between the teeth is less </li></ul></ul></ul></ul><ul><ul><ul><li>Head is inclined </li></ul></ul></ul><ul><ul><ul><ul><li>The distance is greater. </li></ul></ul></ul></ul><ul><li>Therefore the patient's head should be upright and unsupported </li></ul>
  25. 36. The mandible moves about a horizontal axis, as seen in a hinge axis opening.
  26. 37. Mandibular movement occurs around a vertical axis during a lateral excursion.
  27. 38. The mandible also rotates around a sagittal axis when one side drops down during a lateral excursion.
  28. 39. A protrusive movement occurs when the mandible moves forward
  29. 40. When the mandible moves into a left lateral excursion <ul><li>the right condyle (A) </li></ul><ul><ul><li>moves forward and inward </li></ul></ul><ul><li>while the left condyle (B) </li></ul><ul><ul><li>will shift slightly in a lateroposterior direction. </li></ul></ul>
  30. 42. Bennett angle <ul><li>( S'PB ) </li></ul><ul><ul><li>The Bennett angle used in articulators with an immediate lateral translation capability is measured from the sagittal plane after the </li></ul></ul><ul><li>( I ) </li></ul><ul><ul><li>immediate or early lateral translation has occurred. </li></ul></ul>
  31. 43. Bennett angle In the nonworking condyle (NW) <ul><li>The &quot;traditional&quot; Bennett angle </li></ul><ul><li>(SCB) </li></ul><ul><li>measures the angle from the sagittal plane to the endpoint of the movement of the condyle center . </li></ul>
  32. 44. <ul><li>The farther anterior a tooth </li></ul><ul><ul><li>the less the influence of the temporomandibular joint (TMJ) </li></ul></ul><ul><ul><li>the greater the influence of the anterior guidance (AG). </li></ul></ul>

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