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 

Jaw Relations – methods of recording vertical jaw relations 9m #NTRUHS

TYPES OF JAW RELATIONS = this is order of recording 1- 3 

  1. Orientation 
  2. Vertical 
  3. Horizontal
    1. Eccentric = lateral and protrusive 
    2. Centric = recorded last as rims are sealed
  1. How to record VDR? 2M*
    1. Measuring after swallowing and relaxing = tapes on nose and chin
    2. Tactile sense = ask pt to open his mouth at maxium and close the mouth slowly to a rest position = hence, all the muscles will be active
    3. Anatomical Landmarks 
      1. Distance between pupil of eye and rima oris 
      2. Anterior nasal spine and lower border of mandible 
      3. If A = B 
    4. Speech = 
      1. Words ending with M = eg Ram 
      2. Given by Schlossler  
      3. When you pronuch M = lips close 
      4. VDR is more = pt has to keep more effort to bring lips together to say M 
    5. Facial expressions 
    6. Patient position for recording at VDR
      1. Head straight 
      2. Upright position 
      3. Reid base line is parallel to the floor while recording vertical jaw relation 
      4. Draw
  2. How to record VDO? 2M*
    1. Measured when pt is in centric relation 
    2. Mechanical methods
      1. Checking ridge relation 
        1. Distance between incisive papilla to mandibular incisior = 8 mm 
        2. Distance between incisive papilla to maxillary incisior = 6 mm + 2mm overbite
      2. Prextration records = BEST METHOD = Its a model of original VD 
      3. Existing denture 
    3. Physiological method 3m
      1. Given by NISWONGER and THOMSON = 1934
      2. Ask the pt to relax after placing rims in the pt mouth  = This is static method
      3. In this method, two markings are made, one on the upper lip below the nasal septum, and the other on the chin. 
      4. The patient is told to swallow and relax. 
      5. The distance between the marks is measured. 
      6. The occlusal rims are adjusted, until the distance between the marks is 2–4 mm less during occlusion. 
      7. Disadvantage: The marks move with the skin. 
    4. Phonetics 
      1. Ask the pt to prounch S or FVS eg 55 
      2. Given by silverman 
      3. This is called closest speaking space = 2mm 
      4. This is recorded in DYNAMIC position when pt is speaking 
      5. FVS sounds = speaking anterior tooth realtion = given by pound and murrell – without recording VD and set up your anterior teeth based on prouncing FVS

What is Residual Ridge Resorption?

  1. RRR means a reduction in residual ridge 
  2. DOES NOT mean residual ridge resorption
  3. chronic, progressive, and irreversible
  4. Proportional to 
    1. Anatomic factors
    2. Bone resportion factors
    3. Force Factors
  5. Inversely proportional to bone-forming factors and damping effect and time
  6. The damping effect means the amount of force that can be absorbed without damaging the ridge.

LOCAL FACTORS IN COMPLETE DENTURE

  1. Broad square ridges devoid of undercuts and bony abnormalities.
  2. Definite cuspid eminences and alveolar tubercules; a broad palate with uniform depth of vault in the maxillary arch.
  3. Broad buccal shelf and firm retromolar papillae in the mandibular arch.
  4. A definite vestibular fornix, devoid of muscle attachments.
  5. Frenum attachments high in the maxillary and low in the mandibular arches.
  6. A clearly defined and well-developed lingual sulcus.
  7. A lateral throat form that allows suitable extension into the retromylohyoid space.
  8. A firm mucosal covering over the denture-bearing area.
  9. Mucous membrane in the vestibule fornix and floor of the mouth which is loosely and movably attached for denture seal.
  10. A gradually sloping palate with a passive reflection at the junction of the hard and soft palate.
  11. A tongue normal in size, position, and function.
  12. A normally related maxilla to mandible.
  13. Good muscle tonus and coordination in mandibular movements.
  14. Adequate inter-ridge space for the favourable placement of teeth
  15. Saliva of suitable viscosity and quantity
  16. Hard and soft tissues devoid of any signs of pathologic disorder.

Reference: Syllabus of Complete Denture By HEARTWELL – 4th edition

DAVIS CROWN

(WALLACE CLYDE DAVIS) 1866-1950

  • This is a dental restoration supported by a dowel in the root canal over which a porcelain tube teeth is placed directly on the root face of the tooth.
  • It is one type of dowel crown, which is detachable or called as the detached dowel type.
  • It is cemented in position uniting the tooth, dowel and crown into one unit.

1. When excessive tooth decay has occurred, there will be discrepancy between the fit of the crown and root planes. The cast base is attached to the dowel.

2. Porcelain is fused and interposed between the crown and root planes.

1. Preparation if labial and lingual planes is done

2. A complete porcelain crown of proper mould, size amd shape is selected.

3. The dowel is fitted in the root canal.

4. A platinum ferrule (0.0005 inch thick) is adapted on the dowel extension.

Porcelain crown is placed over the dowel and ferrule.

The crown position, with adjacent teeth and alignment is verified and the crown is fitted to the dowel with sticky wax and removed.

• A platinum foil 0.0001 inch is burnished onto the root face of die and the crown, ferrule and dowel is seated on platinum foil.

• The gap between the porcelain crown and swaged platinum matrix is sealed with melted inlay wax and is removed.

• This is invested and burn out done to remove the inlay wax. The temperature of furnace is raised to 1093°C and medium-fusing porcelain is placed at the area where wax has burned out.

• Depending on the morphology, porcelain can be added and fired to form the correct contours. Excess porcelain is ground and glazed to complete the restoration.

Reference : Exam Preparatory Manual By Lovely M on Fixed Partial Dentures