Horizontal Jaw Relation/ Centric Relation – Methods of Recording 9m #NTRUHS

  1. Types of Horizontal Jaw Relations
    1. Centric 
    2. Eccentric 
      1. Lateral = right and left 
      2. Protrusive 

CENTRIC RELATION 

  1. Definition = When the condyle is in most anterior superior position in the glenoid fossa 
  2. When pt has teeth = entire proprioception is derived from PDL 
  3. When pt is edentulous = proprioception is derived from TMJ 
  4. When pt has teeth = it is centric occluded = also know as maximum intercuspal position 
  5. When pt is edentulous = we need to record centric relation 
    1. These pt have habitual prognathism = move mandible forward and chew the food using anterior ridges 
    2. Important muscles = masseter and temporalis 
    3. We ask pt to relax – bring his or her upper jaw forward 
    4. Touch the tongue on most posterior part of hard palate
  6. HOW TO RECORD?
    1. PHYSIOLOGICAL 
      1. Tactile 
      2. Pressure 
      3. Pressureless  
    2. FUNCTIONAL = chew in methods 
      1. Needlehouse 
      2. Patterson 
    3. GRAPHIC = tracing in the shape of arrow 
      1. Intraoral 
      2. Extraoral 
    4. RADIOGRAPHIC = identify the position of condyles in fossa 
  7. Tactile interocclusal records
    1. Do a tentative jaw relation 
    2. Do teeth arrangement 
    3. Place in patient mouth and take interocclusal record = Using wax or alu wax 
    4. Re-articulate and finalize arrangement 
    5. Wax = 2mm of I/O record 
    6. Technique = static 
  8. Pressureless method’
    1. Also called as Nick and Notch method
    2. Best method for reproducibility and cross verification 
    3. Using ZnOE paste or Alu wax 
  9. Pressure technique 
    1. Maxillary rim of normal size
    2. Mandible rim = excess height and soft wax 
    3. Ask the pt to bite on it 
    4. Excess wax moves out 
    5. Hence, we can seal the CR record 
  10. Needle house
    1. Occlusal rims are not made with wax 
    2. Rims are made with impression compound 
    3. Ask pt to do chewing motions and biting movements 
    4. We will observe = Diamond tracing on the rims 
    5. Hence, CR recorded
  11. Patterson 
    1. Trench made in the mandibular rim 
    2. 1:1 carborundum and dental plaster is placed in the trench 
    3. Ask the pt to do mandibular movements = all the excess paste will flow out 
    4. Hence, height is reduced and staple pins are used 
  12. Graphic 
    1. Arrow shape tracing = draw 
    2. Tip of the arrow denotes centric relation 
    3. This is a static record 
    4. Most reliable method of recording centric relation = GOTHIC ARCH TRACING 
    5. Mc pt will give rounded or tilted lines instead of ideal straight line
    6. Intra oral and extra oral tracings = records CR in horizontal plane 
    7. Pantographic tracing 
      1. Record all 3 planes
      2. Also record 4th dimension called TIME
      3. NOT USED in CD 
      4. Primarily used in full mouth rehabilitation 

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