Transcript DEFINTIONS - BMC

JAW RELATION


“ It is any relation between the mandible
and the maxilla.”
It is a three dimensional relation ( vertical,
anteroposterior and lateral).
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
VDO
The vertical dimension of the face when the
teeth are in contact in centric occlusion.
Vertical Dimension of rest
VDR
The vertical dimension of the face when the
mandible is in rest position.
VDR
VDO
Vertical Dimension
Inter Occlusal Distance
(Free Way Space)
= 2 to 4 mm.
(FWS)
(0 to 10 mm.)
V
D
O
VDR - FWS =
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)

1.
2.
3.
4.
5.
6.
7.
8.
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. )

Extension

Retention

Stability



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.




Aesthetic
Phonetic
Functional
Mechanical
base.
base.
base.
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 :
1. Position of the patient's head .
2. Respiration.
3. Stress Situations .
Long Term Variables :
1. 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
1- Extensor
2- Facial
muscles
appearance
are strained.
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
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.
1.
2.
3.
4.
5.
6.
7.
8.
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. )
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
Mandibular
Maxillary
“A device used to locate the
transverse hinge or the
condylar axis.”
“A device used to record the
relation between the maxilla
and the TMJ and to transfer
this relation to the
articulator.”
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.
Graduations on the rod
Components:
Graduated
Condylar Rods
Bite Fork
Infraorbital Pointer
Tightening clamp
Universal Joint /
Jack Clamp
U Shaped Bow
1- Bite fork is heated and inserted into the rim
.
11- 13 mm
2-The condylar axis is then determined
4- Universal joint once tightened , never opened.
1- The slide bar clamp is unscrewd to remove assembly
from the face.
2- Assembly is now centralized on the articulator.
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
3- Graphic tracing method
The resulting arrow represents
the centric and eccentric relations
A- Intraoral tracer
B- Extraoral tracer
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
or
Wax wafer method
Excursive methods
or
Graphic tracing
method
Protrusive record
Right lateral record
Left lateral record
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.