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horizontal jaw relation.pptx

  1. 1. AKANKSHA JR II DEPARTMENT OF PROSTHODONTICS AND CROWN & BRIDGE
  2. 2. HORIZONTAL JAW RELATION Centric relation Eccentric relation Theories Methods of recording Physiological Functional Graphic Protrusive Lateral Clinical outcome
  3. 3. “ Any spatial relationship of the mandible to the maxilla
  4. 4. HORIZONTAL JAW RELATION It is the relationship of the mandible to the maxilla in a horizontal plane The relationship of the mandible to the maxilla in the anteroposterior direction
  5. 5. It can be of two type Centric relation Eccentric relation Protrusive relation Lateral relation
  6. 6. CENTRIC RELATION The most retruded relation of the mandible to the maxilla when the condyle are in the most posterior unstrained position in the glenoid fossa from which lateral movements can be made, at any given degree of jaw separation GPT 1
  7. 7. CENTRIC RELATION A maxillomandibular relationship, independent of tooth contact, in which the condyles articulate in the anterior-superior position against the posterior slopes of the articular eminences in this position, the mandible is restricted to a purely rotary movement; from this unstrained, physiologic, maxillomandibular relationship, the patient can make vertical, lateral or protrusive movements; it is a clinically useful, repeatable reference position GPT 9
  8. 8. MUSCLES INVOLVED IN CENTRIC RELATION The masseter, temporalis and medial pterygoid muscle connects the mandible to the lateral pterygoid plate in such a way as to act as the steering mechanism for the mandible and helps in elevating mandible to centric relation position
  9. 9. Significance of Centric Relation Centric relation position acts as a proprioceptive center to guide the mandibular movements
  10. 10. Purpose of recording centric relation  It is bone to bone relation and it is constant  It is repeatable and recordable and thus serves as reliable guide for developing centric occlusion in complete dentures  It is related to terminal hinge axis
  11. 11. Purpose of recording centric relation  Functional movements like chewing and swallowing can be carried out since it is the most unstrained position.  It is a definite entity, so used as reference point in establishing centric occlusion  It is more definite than vertical relation since it is independent of tooth contact
  12. 12. Theories of centric relation The muscle theory The ligament theory The osteofiber theory The meniscus theory Saizar P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent. 1971 Dec;26(6):581-91.
  13. 13. The Muscle Theory Defence reflex External pterygoid muscles contract Halts the joint Saizar P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent. 1971 Dec;26(6):581-91.
  14. 14. The Ligament Theory Saizar P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent. 1971 Dec;26(6):581-91. Ligaments binds element of articulation, limit the possibilities of movement and are also capable of determining terminal border position
  15. 15. The Osteofiber Theory Saizar P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent. 1971 Dec;26(6):581-91. Involves a retrusive terminal stop formed by soft tissues of posterior part of glenoid fossa Fibrous stop act as buffer
  16. 16. The Meniscus Theory Saizar P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent. 1971 Dec;26(6):581-91. The posterosuperior surface unfolds along the roof of the glenoid fossa
  17. 17. The Meniscus Theory Saizar P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent. 1971 Dec;26(6):581-91. Disc with their retro meniscal fibrous tissues- stop the retrusive condylar movements
  18. 18. Factors influencing centric relation records Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. 1964. J Prosthet Dent. 2005;93(4):305-310.
  19. 19. Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. 1964. J Prosthet Dent. 2005;93(4):305-310. The resiliency of the supporting tissues Stability of the recording bases Temporomandibular joint and associated neuromuscular mechanisms Pressure applied in making the recording The technique used in making the recording and the recording devices used Skill of the dentist
  20. 20. Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. 1964. J Prosthet Dent. 2005;93(4):305-310. The health and cooperation of the patient The maxillomandibular relationship Posture of the patient Character and size of residual alveolar arch The amount and character of saliva Size and position of tongue
  21. 21. Retruding the mandible • Difficulties in Retruding mandible • Methods of Retruding the mandible
  22. 22. Difficulties in obtaining mandibular retrusion Biological Psychological Mechanical
  23. 23. Difficulties in obtaining mandibular retrusion Biological  Lack of muscle coordination  Lack of synchronization between the protruding and Retruding muscles due to HABITUAL eccentric jaw positions
  24. 24. Difficulties in obtaining mandibular retrusion Psychological  Involves patient and dentist  Inability of the patient to follow dentist’s instructions
  25. 25. Difficulties in obtaining mandibular retrusion Mechanical It is essential that the record bases on which the centric relation are made, fit perfectly and not interfere with each other Poorly fitting baseplates
  26. 26. Methods to retrude the mandible while recording centric relation Relaxation of Jaw Simplest, easiest and most efficient way of causing retrusion by verbal instructions to the patient Instruct the patient by saying “ Let your lower jaw relax, pull it back, and close on your back teeth”
  27. 27. Methods to retrude the mandible while recording centric relation Pushing Upper Jaw Patient is instructed to “Get the feeling of pushing your upper jaw out and close your back teeth together” By getting the feeling of pushing the upper jaw forward, they automatically pull the lower jaw backward.
  28. 28. Methods to retrude the mandible while recording centric relation Stretch and Relax Movements Patient is instructed to protrude and retrude the mandible. Dentist can aid by a slight pressure on the point of the chin
  29. 29. Methods to retrude the mandible while recording centric relation Retrusion of Tongue  Patient is instructed to keep the tip of tongue in contact with posterior border of the maxillary record base and then patient is asked to close until the rims come into contact Bissasu M. Use of the tongue for recording centric relation for edentulous patients. J Prosthet Dent. 1999;82(3):369-370.
  30. 30. Methods to retrude the mandible while recording centric relation Rapid Tapping of the Occlusal Rims  Gentle tapping of occlusal rims rapidly and repeatedly retrudes the mandible
  31. 31. Methods to retrude the mandible while recording centric relation Head Position  Tilting the head backwards results in retrusion of the mandible as this will place tension on the infra-mandibular muscles and tend to pull the mandible to a retruded position
  32. 32. Methods to retrude the mandible while recording centric relation Swallowing and Temporalis muscle check  Swallowing usually brings the mandible in a retruded position  The temporalis muscle show reduced function when the mandible is in protruded position. So its contraction can be felt when the mandible is in or near retruded position by placing finger tips on each side of the head
  33. 33. Recording Centric Relation • Minimum pressure technique • Heavy pressure technique
  34. 34. Minimum closing pressure  The record should be made with minimal closing pressures so the tissues supporting the bases will not be displaced while record is being made.  Objective : For the opposing teeth to touch uniformly and simultaneously at their first contact
  35. 35. Heavy closing pressure  The record should be made under heavy closing pressure so that record bases will be displaced while the record is being made.  Objective : To produce the same displacement of the soft tissues as would exist when heavy closing pressure were applied to denture
  36. 36. Methods of Recording Centric Relation
  37. 37. Boucher Static methods Functional methods Interocclusal records with/without central bearing devices and tracing devices Chew in technique : • NeedlesHouse technique • Patterson technique
  38. 38. Physiological methods Functional methods Graphic methods Radiographic method Tactile method / Interocclusal check records Chew in technique : • Needles House technique • Patterson technique • Intraoral devices • Extraoral devices
  39. 39. Kapur and Yurkstas ( 1957)
  40. 40. PHYSIOLOGICAL METHODS
  41. 41. The proprioceptive impulses of the patient Kinesthetic sense of mandibular movement The visual acuity and sense of touch of the dentist No pressure is exerted on the interocclusal record
  42. 42. Tactile sense or Interocclusal check record method
  43. 43. Commonly used materials Waxes Impression compound Zinc oxide eugenol paste Impression plaster Additional silicone Polyether usually preferred because they offer uniform resistance to pressure
  44. 44. Tentative jaw relation Maxillary occlusal rim is inserted into patients mouth Vertical dimension at rest is established Tentative centric relation is recorded by Retruding the mandible Occlusal rims articulated and artificial teeth arranged Trial dentures ready for making interocclusal check record
  45. 45. Making inter-occlusal check record The trial dentures are removed and the wax is allowed to cool Aluwax is loaded onto the occlusal surface of teeth in the mandibular occlusal rim The patient is asked to slowly retrude the mandible and close on the was till tooth contact occurs The upper and lower trial dentures are inserted into patients mouth Artificial teeth are prevented from contacting the opposing members by keeping a piece of cotton inter-occlusally
  46. 46. Making inter-occlusal check record
  47. 47. Factors affecting the success of interocclusal record method Uniform consistency of the recording material. Accurate vertical jaw relation records. Stability and fit of the record base. Presence of reference points embedded in the record like metal pins or styli.
  48. 48. Static or Pressureless Method The occlusal rims are customized as usual and the patient is trained to close at centric relation position. Once the patient attains the centric relation position, the denture bases with occlusal rims are indexed/sealed in this position Nick and Notch method Stapler Pin method
  49. 49. Nick and Notch method • Most commonly used method of indexing the centric record • Final centric jaw relation is carried out after establishing a proper vertical jaw relation • No occlusal check record is performed during try-in
  50. 50. The patient is seated in an upright position Up to 3 mm of wax is removed on either side of the mandibular occlusal rim from the premolar region till the distal end. This depression created on the occlusal rim due to removal of wax is called trough
  51. 51. One or two notches are cut on the corresponding area on the maxillary occlusal rim. The notch resembles a "V“ shaped valley running totally across the width of the occlusal rim One nick is cut anterior to the notch. This is also a "V“ shaped valley but it does not extend throughout the width of the occlusal rim
  52. 52. the nick and notch on maxillary occlusal rim are lubricated with petroleum jelly The prepared occlusal rims are inserted into the patient’s mouth and the patient is taught to close his mandible in centric position Mandibular occlusal rim removed from the mouth Bite registration material is placed in the trough created in the mandibular occlusal rim
  53. 53. The mandibular occlusal rim is placed back in patient’s mouth and patient is asked to close in centric relation The mouth should close such that the anterior parts of the occlusal rim almost touch but not press against it Both the rims are removed, cooled and excess material is trimmed
  54. 54. Stapler pin method • In this method, after recording the centric relation, the occlusal rims are indexed using a bunch of stapler pin. • The method is not preferred as centric relation record cannot be verified
  55. 55. Pressure Method • After establishing the vertical dimension, the maxillary occlusal rim is inserted into patient’s mouth • The mandibular rim is fabricated excess of height • The entire mandibular rim is softened in water bath and inserted into patient’s mouth • Patient is guided to close in centric relation and asked to close on soft wax • After patient closes mouth till the predetermined vertical dimension, both rims are removed , cooled and articulated
  56. 56. Shanahan technique The cones made up of soft wax were mounted on the mandibular occlusal rim Patient was advised to make swallowing movements several times, while the tongue would force the mandible into its centric relation position The cones of soft wax were moulded during these movements Shetty, Manoj & Shetty, Ganaraj. (2020). Comparative Evaluation of Various Techniques to Record Centric Relation- A Literature Review. Journal of Evolution of Medical and Dental Sciences. 09. 53-59. 10.14260/jemds/2020/12.
  57. 57. FUNCTIONAL METHODS • Needles House technique • Patterson technique
  58. 58. • Utilizes the functional movements to record the centric relation • Patient is asked to perform border movements such as protrusive and excursive movements , in order to identify the most retruded position of mandible
  59. 59. Factors common to all functional methods Tentative centric relation and vertical dimension are measured for determining an accurate centric relation Occlusal rims are reduced in excess than that required for tentative vertical dimension Exact vertical dimension at occlusion is determined only when the patient closes on the occlusal rims and their attachments Needles House Patterson Meyer
  60. 60. Disadvantages Inaccuracy can result from: • Displaceable basal seat tissues • Resistance of recording mediums • Lack of equalized pressures Patients must have very good neuromuscular coordination and be capable of following instructions
  61. 61. Needleshouse Method Involves fabrication of occlusal rims made from impression compound 4 metal beads or styli are embedded into premolar and molar areas of maxillary occlusal rim
  62. 62. Diamond shaped pattern
  63. 63. Patterson Method Involves fabrication of occlusal rims made from modelling wax Trench or trough is made along the length of mandibular occlusal rim
  64. 64. Movements will produce compensating curves on the plaster carborundum mix
  65. 65. As these movements are made, the height of the plaster carborundum mix is also reduced. The patient is asked to continue these movements till a predetermined vertical dimension is obtained. Finally the patient is asked to retrude his jaw and the occlusal rims are fixed in this position with metal staples.
  66. 66. Meyer method ( modified functional technique ) Soft wax was utilized to make occlusal rims The occlusal surface of the wax was coated with tinfoil Mandible was guided to perform functional movement and later plaster index was made on wax rims. Plaster index was used as a guide to set the teeth Shetty, Manoj & Shetty, Ganaraj. (2020). Comparative Evaluation of Various Techniques to Record Centric Relation- A Literature Review. Journal of Evolution of Medical and Dental Sciences. 09. 53-59. 10.14260/jemds/2020/12.
  67. 67. GRAPHIC METHODS
  68. 68. Uses graphs or tracings to record the centric jaw relation Graphic methods Arrow point tracing Measured along a single plane Pantograph Measured three- dimensionally
  69. 69. Arrow point tracing , Needle point tracing Gothic Arch Tracing
  70. 70. Why “ Gothic Arch “ ? Arrow point tracing was first proposed by Hesse 1897, and later popularized by Gysi, 1908
  71. 71. Historical review of graphical recordings Balkwill (1866) • Earliest graphic recordings based on mandibular movements • The intersection of the arcs produced by the right and left condyles formed the apex of what is known as the Gothic arch tracing. Myers ML. Centric relation records-historical review. J Prosthet Dent. 1982;47(2):141-145
  72. 72. Historical review of graphical recordings Gysi (1910) • Extraoral incisal tracer on maxillary rim traced onto the tracing plate, coated with wax attached with mandibular rim • The rims were made of modeling compound to maintain the vertical dimension of occlusion Myers ML. Centric relation records-historical review. J Prosthet Dent. 1982;47(2):141-145
  73. 73. Historical review of graphical recordings Sears • Used lubricated rims for easier movement. • He placed the needle point tracer on the mandibular rim and the plate on the maxillary rim. • He believed this made the angle of the tracing more acute and more easily discernible. He would then cement the rims together for removal. Myers ML. Centric relation records-historical review. J Prosthet Dent. 1982;47(2):141-145
  74. 74. Historical review of graphical recordings Phillips • Recognized that any lateral movements of the jaw would cause interference of the rims which could result in distorted record. • Developed a plate for the upper rim and a tripoded ball bearing mounted on a jackscrew for the lower rim “Central Bearing Point “ This innovation supposedly produced equalization of pressure on the edentulous ridge Myers ML. Centric relation records-historical review. J Prosthet Dent. 1982;47(2):141-145
  75. 75. Historical review of graphical recordings Stansbery (1929) • Used a curved plate corresponding to monson’s curve mounted on upper rim. A central bearing screw was attached to lower plate with a 3inch radius curve. After extraoral tracing , plaster was used to form a biconcave centric registration Myers ML. Centric relation records-historical review. J Prosthet Dent. 1982;47(2):141-145
  76. 76. Historical review of graphical recordings Silverman • Used an intraoral gothic arch tracer to locate the “biting point” of the patient. • The patient was asked to bite on hard tracing plate. This developed a functional resultant of the closing muscles which would retrude the mandible. • The indentation made by the patient would be used for centric record whether it corresponds to gothic apex or not Myers ML. Centric relation records-historical review. J Prosthet Dent. 1982;47(2):141-145
  77. 77. Arrow point tracing The pattern obtained on the horizontal plate with a central bearing tracing device
  78. 78. Concept of arrow point tracing The concept consists of attaching a stylus (a writing device with a pointed end) to one occlusal rim and a plate to the other rim. The stylus traces or marks the path in the plate as the mandible performs excursive movements from the centric position. The tracing is typically in the shape of a ‘gothic arch’ or ‘arrow head’ if the patient is trained to move the mandible from centric to protrusive, right and left lateral positions
  79. 79. Central bearing tracing device A device that provides a central point of bearing or support between the maxillary and mandibular dental arches. It consists of a contacting point attached to one dental arch and a plate attached to the opposing dental arch. The plate provides the surface on which the bearing point rests or moves and on which the tracing of the mandibular movement is recorded. It may be used to distribute the occlusal forces evenly during jaw relation and/or for the correction of disharmonious occlusal contacts.
  80. 80. Central bearing point The contact point of central bearing device
  81. 81. Triangular plate of metal with extensions provided to attach itself to the occlusal rim In the center of the triangle a metal pointer is present
  82. 82. Central bearing plate It is also a triangular piece of metal with extensions at the three corners provided to attach the plate to the occlusal rim
  83. 83. Components Tracers Extraoral Intraoral
  84. 84. Extraoral tracer components
  85. 85. Intraoral tracer components
  86. 86. Gothic arch tracing Advantages • Most accurate method of recording CR • Allows equalisation of pressure on supporting tissues • Easy verifiable • Can also be used to record eccentric relations Disadvantages • May be difficult to locate the centre of the arches • More time consuming • Training patient in making mandibular movements is strenuous
  87. 87. Important factors in graphical recordings  Displacement of the record bases may result from pressure if the central bearing point is off center, when the mandible moves into eccentric relations to the maxillae  If a central bearing device is not used, the occlusion rims offer more resistance to horizontal movements  It is difficult to locate the center of the true arches to centralize the forces with a central bearing device when the jaws are in favorable relation and far more difficult if the jaws are in excessive protrusive or retrusive relation. Bansal S, Palaskar J. Critical evaluation of various methods of recording centric jaw relation. J Indian Prosthodont Soc 2008;8:185-9
  88. 88. Important factors in graphical recordings  It is difficult to stabilize a record base against horizontal force on residual ridge that have no vertical height.  It is difficult to stabilize a record base against horizontal forces on tissues that are pendulous or otherwise easily displaceable.  It is difficult to stabilize a record base or bearing device with patients who have large awkward tongues. Bansal S, Palaskar J. Critical evaluation of various methods of recording centric jaw relation. J Indian Prosthodont Soc 2008;8:185-9
  89. 89. Important factors in graphical recordings  Recording devices are not usually considered compatible with normal physiologic simulation in mandibular movement.  The tracing is not acceptable unless a pointed apex is developed, a blunt apex usually indicates an acquired functional relationship and a sharp apex usually indicates the position of centric relation.  Double tracings usually indicate lack of coordinated movements or recordings at a different vertical dimension of jaw separation. In either event, additional tracings are necessary Bansal S, Palaskar J. Critical evaluation of various methods of recording centric jaw relation. J Indian Prosthodont Soc 2008;8:185-9
  90. 90. Important factors in graphical recordings  A graphic tracing to determine Centric Relation is made at the predetermined vertical dimension of occlusion. This harmonizes Centric Relation with centric occlusion and the antero-posterior bone to bone relation with the tooth-to-tooth contact  Graphic methods can record eccentric relations of the mandible to the maxillae.  Graphic methods are the most accurate visual means of making a Centric Relation record with mechanical instruments; however, all graphic tracings are not necessarily accurate Bansal S, Palaskar J. Critical evaluation of various methods of recording centric jaw relation. J Indian Prosthodont Soc 2008;8:185-9
  91. 91. Indications  Broad edentulous sides  Adequate interarch space  In patients with habitual centric (a more anterior position of the jaws due to prolonged edentulous period without tooth replacement), the use of the graphic method eliminates all occlusal contacts on the rims, thus breaking the neuromuscular reflex and allows the patient to record his true centric
  92. 92. Contraindications  Severely resorbed ridges and excessively flabby ridges as they lead to instability of denture bases  Decreased interarch space – difficult to place central bearing device without raising the vertical dimension  TMJ arthropathy  Abnormal jaw relations
  93. 93. “ REVIEW OF LITERATURE
  94. 94. In 1927, Hanau conceded that the Gysi tracing was satisfactory to check records, but that universal usage was not good Tech stated that the Gysi tracing technique was the only means that should be used for centric records, all other methods were “mere deceptions and playthings”. Kingery pointed out several drawbacks in the use of the central bearing point and added that the “central bearing point allows for no control over the amount of closing pressure applied by the patient.” Bansal S, Palaskar J. Critical evaluation of various methods of recording centric jaw relation. J Indian Prosthodont Soc 2008;8:185-9
  95. 95. Kapur and A. Albert Yurkstas told that intraoral tracing procedure and extraoral tracing procedure were more consistent as compared to wax registration method Phillips pointed to various errors produced by GYSI’s technique and stated that, “if one occlusal rim is allowed to touch the other during the lateral extreme positions, undue pressure is bound to be exerted on the contact side, and on account of resiliency of the underlying tissues the side not in contact will be unseated just enough to cause a false reading for the horizontal inclination of the condylar path”. Bansal S, Palaskar J. Critical evaluation of various methods of recording centric jaw relation. J Indian Prosthodont Soc 2008;8:185-9
  96. 96. A. Albert Yurkstas, and Krishan K. Kapur. Factors influencing centric relation records in edentulous mouths., Journal of Prosthetic Dentistry 1957 Trapozzano stated “the use of the central bearing point is based on the fallacious assumption that the central bearing point will produce equalization of pressure. Trapozzano maintained that the wax recording method was the most accurate method because of the greater ability to equalize or centralize pressure with this technique.
  97. 97. Intraoral tracing devices and tracing procedure
  98. 98. Coble balancer The central bearing pin is a small cylinder attached to maxillary denture base The central bearing plate is narrow and is designed like a bridge across lower occlusal rim
  99. 99. Condylator The central bearing pin is attached to mandibular occlusal rim The central bearing plate is trapezoidal in shape
  100. 100. Ballard intraoral tracer The tracing pin is attached to mandibular rim and plate to maxillary rim • Palatal bearing plate • Rounded head of correlator pin • Tension spring • Mounting plate • Pointed end of correlator pin
  101. 101. Swiss dent ball bearing bite recorder The central bearing point is a ball with a single point of contact . The ball add weight and stability to the tracer
  102. 102. Microtracer It is a circular tracer with a semi-circular central bearing point. It is more comfortable for the patient
  103. 103. Procedure for intraoral tracing  The record bases attached to tracing point and plate are inserted into patients mouth  The central bearing point is adjusted such that it contacts the plate at predetermined vertical dimension
  104. 104. Procedure for intraoral tracing  The patient is asked to make anteroposterior and lateral movements. While making these movements, the central bearing point will draw the tracing pattern on the plate
  105. 105. Procedure for intraoral tracing  When the patient closes the mouth, the central bearing point contacts the metal plate
  106. 106. Extraoral tracing devices and tracing procedure
  107. 107. Hight tracer The Hight tracer has an upper tracing pin and a lower recording plate. These tracers have ‘toothed’ extensions which are used to attach the tracers to the side of the occlusal rims
  108. 108. Sears tracer It is a central bearing point tracer with two tracing apparatus. It produces two tracing simultaneously. It is the only extra oral tracer which has the tracing pin attached to the mandible and the plate attached to the maxilla
  109. 109. Phillips extraoral tracer Extraoral device with two tracing apparatus The tracing pin is attached to the maxilla and the tracing plate is attached to the mandible
  110. 110. Procedure for extraoral tracing  The maxillary cast is mounted on the articulator with face bow transfer  The mandibular cast is oriented to the maxillary cast at the established vertical dimension with a static CR record  The condylar elements of the articulator are secured against the centric stops
  111. 111. Procedure for extraoral tracing The central bearing and tracing devices are mounted on the respective rims
  112. 112. Procedure for extraoral tracing  The patient is seated with head upright, and record bases with attached devices are inserted into patients mouth.  Record bases are checked for stability, contact during movements and interferences
  113. 113. Procedure for extraoral tracing  The stylus is retracted and patient is trained to make various excursive movements passively and actively (if needed). Patient is instructed to move the jaw forwards, right and left from centric position. Ney Excursion Guide
  114. 114. Procedure for extraoral tracing  When the patient is well trained in making the movements, the recording plate is coated with a thin coating of lacquer, precipitated chalk or dark coloured wax  The stylus is made to contact the recording plate and the patient is instructed to make the specific movements.
  115. 115. Procedure for extraoral tracing  When an acceptable tracing is made with a single sharp apex, a centric record is obtained  The rims and tracing are prepared to receive the centric record
  116. 116. Procedure for extraoral tracing Before making the records, the undercuts are blocked with wax and orientation grooves made in the wax.
  117. 117. Procedure for extraoral tracing
  118. 118. Procedure for extraoral tracing  The patient is instructed to retrude the mandible such that the stylus contacts the apex of the tracing  Quick setting plaster is injected between the rims and allowed to harden; thus, the centric record is obtained
  119. 119. Procedure for extraoral tracing The occlusal rims are seated over the casts and with the centric record in place, and the mandibular cast is remounted with the new record.
  120. 120. Gerbers classification of arrow point tracing Well defined apex with a symmetrical left and right lateral component. The mean gothic arch angle is about 120 degrees. It reflects healthy TMJ without interferences in condylar path and balanced muscle guidance Typical
  121. 121. Gerbers classification of arrow point tracing Similar to typical form except that it has more obtuse left and right lateral tracings The gothic arch angle is more than 120 degrees. It signifies marked lateral movement of condyle in the fossa. Flat form
  122. 122. Gerbers classification of arrow point tracing The tracing should be repeated till a defined arrow point head is obtained. Patient training is necessary Round form / apex absent
  123. 123. Gerbers classification of arrow point tracing Similar to typical form, however the extension of tracing is very limited. This can be due to restricted mandibular movements, improper seating of denture bases and painful fitting denture bases. It is also an indication of long period of edentulousness with an inhibition in condylar movements Miniature arrow point
  124. 124. Gerbers classification of arrow point tracing It is a record of habitual and retruded centric relation Also seen when vertical dimension is altered during registration Double arrow point
  125. 125. Gerbers classification of arrow point tracing The protrusive path of mandibular movement extended beyond the apex of the Gothic arch. This signifies a forced strained retrusive movement of lower jaw either by patient or operator. It is also seen when the patient head is tilted too far posteriorly Dorsally extended arrow point
  126. 126. Gerbers classification of arrow point tracing It is break or loss of continuity of lateral insical path of gothic arch This happens due to posterior interferences at the heels of the denture base Interrupted arrow point
  127. 127. Gerbers classification of arrow point tracing The left and right lateral tracings meet in an arrow point; however, the inclination to the protrusive movement obtained is not symmetrical. This form of tracing indicates an error or interference in forwarding movement of the condyle. Asymmetrical arrow point
  128. 128. THANK YOU !
  129. 129. Uses graphs or tracings to record the centric jaw relation Graphic methods Arrow point tracing Measured along a single plane Pantograph Measured three- dimensionally
  130. 130. Pantographic tracing A graphic record of mandibular movement usually recorded in the horizontal, sagittal and frontal planes as registered by styli on the recording tables of a pantograph or by means of electronic sensors Pantogram
  131. 131. Pantograph An instrument used to graphically record in, one or more planes, paths of mandibular movement and to provide information for the programming of an articulator
  132. 132. It resembles a complicated facebow The surface over which the tracing is done is called a “ flag “ A stylus (tracing pointer) is present for each flag and it draws tracing patterns on the flags
  133. 133. RADIOGRAPHIC METHOD
  134. 134. CEPHALOMETRIC RADIOGRAPHS Pyott and Schaeffer used cephalometric radiographs to record centric relation and vertical dimension of occlusion However this method never gained widespread due to errors in recording centric relation
  135. 135. Conclusion  Recording of centric relation is the most important factor in dentistry. It is a very critical step.  Therefore, it is recommended to discuss regarding various methods and material aspects used in recording centric relation more precisely.  Skills of the operator and patient’s good neuromuscular coordination are probably the most important factors in securing an accurate Centric Relation record.
  136. 136. THANK YOU !

Editor's Notes

  • Centric relation is not a resting position or postural position of the mandible
    contraction of muscles is necessary to move and fix the mandible in CR position
  • As we know that the proprioceptive impulses(impulses of 3 dimensional spatial orientation) guide the mandibular movements
    in dentulous patients the proprioceptive impulses are obtained from pdl
    Dentulous patient does not have any proprioceptive guidance from the teeth to guide mandibular movements. The source of impulses is transferred to tmj.
  • 3. In CR condyles exhibit pure rotation without any translation
  • 3. In CR condyles exhibit pure rotation without any translation
  • The anatomic mechanism responsible for CR is not unknown and therefore several theories have been developed
  • Or the myologic theory
    This theory considers CR to be product of a defense reflex
    Which halts the joint everytime the condyles approaches the posterosuperior depths of glenoid fossa
  • Ferrin was first to present the theory
    According to this , when the ligamnets become tense they determine the limits of retrusive movement.
  • Proved by meyer
    zenker believed that
    he named this structure as retroarticular cushion
  • The mandible should be retruded to it posterior position before recording the centric jaw relation.
    Some patients may show difficulties in Retruding due to certain systemic conditions
  • Disadvantage : likelihood of displacing the mandibular record base by the action of tongue.
  • Disadvantage : difficult to record and patient can easily tap in a slightly protrusive or lateral position
  • Disadvantage : insertion and removal of occlusal rim from mouth is difficult
  • Disadvantage of swallowing: unreliable since person can swallow when mandible is not completely retruded but 1-2 mm anterior to maxilla.
  • There are 2 basic concepts of closing pressure while recording centric relations each one having its own objective
  • Disadvantage- if soft tissue have uneven thickness, the teeth contact unevenly at first contact
    Uneven contacts may cause clenching in nervous patients .

    Advantage- occlusal pressure are evenly distributed over residual ridges under heavy load.
  • They are called physiological because they are based on
  • Waxes are technique sensistive and do not provide uniform resisitance to pressure they do not cool uniformly
    Advantage of waxes – they harden quickly and record can be made immediately
    Disadvantage of plaster and zoe- they take long time to set
  • The names nick and notch is from the shape of the indices made on the occlusal rims
  • 1. As it is easier to retrude the mandible in this position
  • 1. nick prevents lateral movement and the notch prevents anteroposterior movement
  • The arrow point resembles the high pointed arches of the Gothic architecture and was hence called as 'Gothic Arch Tracing’.
    Also known as needle point tracing
  • When a good tracing was recorded, the patient held the rims in the apex of the tracing while notches were scored in the rims for orientation.
  • The pointer can be adjusted to the height
  • stylus (tracing device) and central bearing plate attached to the maxillary rim.
    2. recording plate (tracing device) and central bearing point (central bearing device) is attached to the mandibular rim.
  • Intraoral tracer components: (a) Recording plate and central bearing plate are combined as one component and attached to maxillary rim.
    (b) The stylus and central bearing point are combined as one component and attached to the mandibular rim.
  • The intraoral tracing procedure has also been criticized by many prosthodontists. Their main objections were based on the general disadvantages of a central bearing point device
  • Popular compact intraoral tracer
  • The tracer are easy to place because they are supplied with snap on spacer that provide even space for bite registration
  • After completing the movements, the tracing is removed and examined .
    The tracing should resemble an arow point with sharp apex. If apex is blunt, the record is discarded and the procedure is freshly repeated.
  • These tracers were originally designed without a central bearing device. They were later modified to include a central bearing device to equalize biting pressure during jaw relation procedures
  • Occlusal rims with the extraoral tracer inserted in the patient’s mouth.
  • 1. The Ney Excursion Guide has been used as an aid in training the patient but patient responds better to specific locations than numbers

    2. The patient is trained to make the mandibular movements in the numerical order.
  • The coating material should not provide any resistance to movement and produce a clearly visible tracing
  • Before making the records, the tracing is protected by a transparent plastic film (b).
    This film is secured over the recording plate using sticky wax (a).
    The centric point of the arrow head is viewed and using a sharp heated needle, a hole is made (c) which will guide the needle in position while making records. 6 mm from the centric point, another slot is made, to stabilize the needle while making the protrusive record.
  • Gerber stated that there are six different types of tracing obtained from Gothic arch tracers based on the direction of movement of condylar head and also on neuromuscular coordination of muscle of mastication and jaw movements.

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