RECORDING OF JAW RELATION

Jaw Relation “ It is any relation between the mandible and the maxilla.” It is a three dimensional relation ( vertical, anteroposterior and lateral).

DEFINTIONS Centric relation (It a bone to bone relation ) It is the most retruded unstrained postion of the condyle in the glenoid fossae

Centric occlusion It the relation of opposing occluding surfaces when the mandible in centric relation to maxilla The centric occlusion May or may not coincide with MI.

Occlusal Vertical Dimension The distance measured between two points when occluding members are in contact in centric occlusion.

Vertical Dimension of occlusion V D O The vertical dimension of the face when the teeth are in contact in centric occlusion.

Vertical Dimension of rest V D R The vertical dimension of the face when the mandible is in rest position.

V D R V D O

Vertical Dimension V D O V D R - F W S = Inter Occlusal Distance (Free Way Space) = 2 to 4 mm. ( F W S ) (0 to 10 mm.) V D O V D R - F W S =

CENTRIC OCCLUDING RELATION IT RECORDING A CENTRIC RELATION AT ACCEPATABLE VERTICAL DIMENSION OF OCCLUSION “ (Centric relation between maxilla and mandible at the proper vertical dimension of occlusion)

RECORDING JAW RELATIONSHIPS Check denture foundation. Establish facial contour. Establish occlusal plane. Maxillary face-bow record. Determination of vertical dimension of centric occluding relation. Equalize pressure of occluding forces. Determine centric relation at the accepted vertical dimension. Locking device ( recording the C.O.R. )

Check denture foundations. Extension Retention Stability

Establish facial contour Facial contour depends on the presence and alignment of teeth. Teeth position or wax rim supports facial musculature and appearance. Position of teeth governs tongue space and neutral zone.

Determination of occlusal plane Aesthetic base. Phonetic base. Functional base. Mechanical base.

Anterior occlusal plane : Parallel to interpupillary line .

Posterior occlusal plane : Parallel to the ala tragus line .

Determination of Vertical Dimension of Centric Occluding Relation

Variables Affecting V D R : Short Term Variables : Position of the patient's head . Respiration. Stress Situations . Long Term Variables : Loss of the properioceptives impulses from the periodontal ligament. 2. Age.

Sequel Of Improper Registration Of V.D.0. A . High Vertical Dimension Of Occlusion : 1- inharmonious facial proportions (Appearance). 2- Flexor muscles are in constant strain. 3- The lips are unnaturally separated and have a strained appearance. 4- The free-way space will be obliterated, inability to find comfortable resting position. 5- Clicking of teeth may occur during speech and mastication.

Sequel Of Improper Registration Of V.D.0. A . High Vertical Dimension Of Occlusion : 6- Generalized soreness of the residual ridge. 7. Difficulty in swallowing and gagging sensation (Discomfort). 8. Loss of biting power and muscular fatigue. 9. Interference with speech . 10. Pain under the basal seat and trauma to the supporting structures . 11. Accelerate bone resorption.

High Vertical Dimension Flabby Tissue

High Vertical Dimension Obliterated free-way space High Plane of Occlusion

Establishing too little V.D. 1- Extensor muscles are strained. 2- Facial appearance is distorted. 3- Corners of the mouth may be inflamed ( angular chielitis ). 4- Pain in tempro-mandibular joint. 5- Cheek biting. 6- Inefficiency: reduces biting force

Cheek Biting Monoplane Heavy Bite No Horizontal Overlap

Angular Cheilitis Corner of Mouth

Trouble in the T.M.J. The symptoms of the joint due to reduced V.D. are manifested by Obscure pains and discomfort, Clicking sounds, Headaches and neuralgia running in the ear. These symptoms may be resulted from pressure on the tympanic nerve.

RECORDING JAW RELATIONSHIPS Check denture foundation. Establish facial contour. Establish occlusal plane. Maxillary face-bow record. Determination of vertical dimension of centric occluding relation. Equalize pressure of occluding forces. Determine centric relation at the accepted vertical dimension. Locking device ( recording the C.O.R. )

FACE-BOWS The face-bow is a caliper-like device that is used to record the relationship of the jaws to the tempromandibular joint or ( opening axis of the jaws ) and to orient the casts in this same relationship to the opening axis of the articulator. The face-bow transfer ensures that the casts are mounted centrally in correct relation to the inter-condylar axis

“A device used to locate the transverse hinge or the condylar axis.” Types of Face Bows Mandibular “A device used to locate the transverse hinge or the condylar axis.” Maxillary “A device used to record the relation between the maxilla and the TMJ and to transfer this relation to the articulator.”

Mandibular Face Bow Limited opening and closing allows the condylar rods to draw arcs. The rods are moved towards the center of the arcs, until they move in a point . The latter is called the still point and represents the condylar axis. The condyle in this position lies in the most retruded unstrained position in the glenoid fossa, so mandible and maxilla are in centric.

Maxillary Face Bow Components: Graduations on the rod Graduated Condylar Rods Infraorbital Pointer Bite Fork Tightening clamp Universal Joint / Jack Clamp U Shaped Bow

Facia face bow

The ear-bow uses the external auditory

Maxillary Face Bow Record 1- Bite fork is heated and inserted into the rim .

Cont. Maxillary Face Bow Record 11- 13 mm 2-The condylar axis is then determined

Cont. Maxillary Face Bow Record 4- Universal joint once tightened , never opened.

Maxillary Face Bow Transfer 1- The slide bar clamp is unscrewd to remove assembly from the face.

Cont. Maxillary Face Bow Transfer 2- Assembly is now centralized on the articulator.

Equalize pressure of occluding forces This means to produce even contact between the upper and lower occlusion blocks without displacement of denture supporting tissues. This can only be done on an easily displaceable material such as softened wax.

Methods of recording the jaw relation 1- Terminal hinge axis method (Mandibular face bow method) 2- Chew-in or functional method 3- Graphic tracing method 4- Check bite / wax wafer/ wax registration method

1- Terminal hinge axis method

2- Chew in technique

3- Graphic tracing method

The resulting arrow represents the centric and eccentric relations

TYPES OF TRACERS A- Intraoral tracer B- Extraoral tracer

4- Check bite technique (Wax wafer method)

Methods to guide the mandible in centric relation 1- Tongue retrusion . 2- Swallowing . 3- Biting operator’s fingers . 4- Relaxation . 5- Fatigue . 6- Head position . 7- The temporalis muscle check .

Wax registration method or Check bites Wax wafer method

Graphic tracing method Excursive methods or Graphic tracing method

Eccentric jaw relationships Protrusive record Right lateral record Left lateral record

Locking device V shaped notches can be carved on the upper occlusion rim and the final closure is done on softened wax. The imprints of these notches are used to lock upper and lower occlusion blocks.