1. Centric Jaw relation
   1. The maxillomandibular relationship in which condyle articulate with thinnest avascular portion of their respective discs with complex in anterior-superior position against the slopes of articular eminence
   2. This position is independent of tooth contact
   3. It's restricted to a purely rotary movement about transverse horizontal axis
   4. Centric Relation (CR)
      1. Relationship of mandible to maxilla when mandible is in its posterior most position
         1. Relation btw Mandible to Cranium
         2. Muscles involved: Masseter & Temporalis
         3. Discrepancy between CR & CO is called "freedom from centric" or Long centric. It is 0.5-1.5mm
         4. CR is the most accurately reproducible & reliable relationship from recording Jaw relation. Least reproducible is Protrusive relation
   5. Centric Occlusion(CO)
      1. Occlusion of opposing teeth when mandible is in CR
      2. This may or may not coincide with MIP(Maximum intercuspation)
   6. Fischer's angle
      1. Angle formed by protrusive & non-working condylar paths, viewed in sagittal plane
2. Methods to record CR
   1. 1) Physiological methods
      1. Tactile/interocclusal check records
      2. Pressure-less method
         1. "Nick & notch" method
      3. Pressure method
   2. 2) Functional methods
      1. Needlehouse method
      2. Patterson method
      3. Mayer's method
   3. 3) Graphic methods
      1. Intra oral
         1. Gothic arch tracing/Arrowhead tracing/Needle point tracing
      2. Extraoral
         1. Devices used : Seidel, Ballard, Masserman tracers
3. Types of occlusal interferences
   1. ▪︎Interferences are undesirable occlusal contacts that may produce mandibular deviation during closure to & from MIP
   2. 4 TYPES
      1. In CO or MIP
         1. Centric occlusal interferences may produce clenching & or bruxism with their associated symptoms of muscle pain & fatigue.
         2. ▪︎Mandible is closed in CR until initial tooth contact occurs ▪︎If increasing the closing force deflects the Mandible, premature contact or interference exists ▪︎This leads to deflection of mandible which can be posterior, Anterior &/or lateral direction ▪︎Interferences occurs btw mesial inclines of maxillary posterior teeth & distal inclines of mandibular posterior teeth
      2. During Working movements
         1. ▪︎Occurs when there is contact btw maxillary & mandibular posterior teeth on working side & this causes anterior teeth to disocclude ▪︎Occurs on maxillary lingual facing cusp inclines & mandibular buccal facing cusp inclines
      3. During Non-working movements
         1. Most destructive
         2. ▪︎It's an occlusal contact between maxillary & mandibular teeth on non-working side when mandible moves in a lateral excursion ▪︎Occurs on maxillary buccal facing cusp inclines & mandibular lingual facing cusp inclines
      4. During Protrusive movements
         1. ▪︎Occurs when distal facing inclines of maxillary posterior teeth contacts the mesial facing inclines of mandibular posterior teeth during protrusive movement
4. OTHER KEY POINTS
   1. Mandibular movements
      1. Translatory movements of condyle & articular disk are controlled by : Capsular ligament & superior head of condyle
      2. Protrusive movement - occurs while incising & grasping food This movement occurs after the condyles rotate for more than 13° in TMJ Characteristic posterior separation seen during anterior protrusion is called "Christensen's phenomenon"
      3. Minimum protrusive movement required ror establishing condylar guidance is 6mm
      4. Progressive lateral translation of condyle occurs at a rate proportional to : forward movement of Non-working condyle
      5. Lateral movements are of 2 types- Lateral rotation & Bennet movement Lateral movement is rotation of mandible to any 1 side. For eg. mandible is moved in right side, the right condyle is considered as working or laterotrusive condyle & left condyle is called as Non-working or Mediotrusive or Balancing side condyle
      6. Bennett angle is seen during - Lateral movement of mandible
      7. Laterotrusion
      8. Laterosurtrusion
      9. Laterodetrusion
      10. Lateroprotrusion
      11. Lateroretrusion
      12. Laterally & outwards
      13. Laterally & upwards
      14. Laterally & downwards
      15. Laterally & forwards
      16. Laterally & backwards