Biological
Consideration of
Jaw Relations
Why to Record
the Jaw
Relations ?
Why to Record the Jaw Relations ?
Why to Record the Jaw Relations ?
To best control the undesirable effects of
rotational or torquing forces on the prosthesis.
To prevent any deflective contacts of the teeth
during centric or eccentric closures as these can
produce pathological changes in the supportive
structures or in the neuromuscular mechanism that
controls mandibular movement.
RECORDING JAW RELATIONSHIPS
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.
Jaw Relation
Records
Vertical
Jaw
Relations
Orientation of Occlusal Plane
Determination
of occlusal
plane
Aesthetic
base.
Phonetic
base.
Mechanical
base.
Functional
base.
Posterior occlusal plane
Anterior occlusal plane
→ Parallel to interpupillary line .
Clinical tips
→ The vertical length of the maxillary occlusion rim
Anterior occlusal plane
→ The vertical length of the maxillary occlusion rim
Clinical tips
→ The vertical length of the mandibular occlusion rim
Fox bite or Fox plane
Importance of orientation of occlusal plane
Importance of orientation of occlusal plane
Vertical Jaw
Relations:
Rest
Vertical
Dimension
‘RVD’
The distance between two selected points one on the fixed
part (maxilla) and one on the movable part (mandible)
when the maxillofacial musculature is in a state of tonic
equilibrium.
Occlusion
distance between two selected points one on the fixed
Vertical the
part (maxilla) and one on the movable part (mandible)
Dimension when occluding members (teeth) are in contact.
‘OVD’
Rest Vertical Dimension
Inter-occlusal
Distance
Freeway space
The distance between the occluding surfaces
of maxillary and mandibular teeth when the
mandible is in the rest position.
In natural dentition, it’s usually 2-4mm in the
premolar area.
For a complete denture patient, it is the
difference between RVD and OVD.
RVD – OVD = FWS
Recording the Rest Vertical Dimension
physiological methods
reference points
opening - closing
em
skin tone and the lips contour
Willis guide
Recording the Rest Vertical Dimension
→ mechanical methods
→
Pre-extraction records
→
Profile photographs
→
Radiography (cephalometric profile and the condyles in the fossae)
→
Articulated cast
→
Facial measurements
→
Former dentures
→
Edentulous patients (wax occlusion rims)
Evaluating vertical dimension
→ inter occlusal distance (free way space)
2-4 mm
→ closest speaking space
→ Patients tactile sense
→ Swallowing followed by relaxing
→ Phonetics
What If
Sequel of High VDO
Excessive display
of mandibular
teeth
Patient unable to
wear dentures
Muscles of
mastication
fatigue
Clicking of
posteriors when
speaking
Strained
appearance of
Lips
Discomfort
Excessive trauma
to supporting
tissues
Gagging
Insufficient Low VDO
Aging appearance of lower third
of face because of thin lips,
wrinkles, chin too near to nose,
overlapping corners of mouth
Interocclusal space is more than 4
mm
Which can lead to
Diminished occlusal forces
Angular Chelitis
Face Bow
Types of Face Bows
Horizontal
relations
Each Condyle Moves About 3 Axes
Sagittal
Horizontal
Vertical
Compensating Curve
Movements of the Mandible
Movements of the Mandible
Movements of the Mandible
→ Bennett movement
Horizontal relations
relationship of mandible to maxilla in a horizontal plane
Centric
relation
Eccentric
relation
Eccentric Jaw Relation
Centric Jaw Relation (CR)
When to use CR
Significance of CR (Reasons for Using CR in Edentulous Patients)
1.
2.
3.
4.
5.
Significance of CR (Reasons for Using CR in Edentulous Patients)
6.
7.
8.
METHODS USED TO MAKE CENTRIC RELATION
RECORD
 FUNCTIONAL
 Needlehouse method
 Patterson method
 GRAPHIC
 Intra oral
 Extra oral
 PHYSIOLOGICAL
 tactile or inter occlusal check
record method
 Pressureless method
 Pressure method
 Other methods
→ Swallowing method
METHODS USED TO MAKE CENTRIC RELATION
RECORD
1- Functional (chew in)
Needles – House
Patterson technique
Functional (chew in)
Functional (chew in)
Graphic Method
Graphic Method
PHYSIOLOGICAL

o
o
o
PHYSIOLOGICAL

Swallowing method
Methods To Assisting Patients To Move The Mandible To The
Centric Relation
The dentist should guide the patient to the centric
relation, not force the patient
1.
The patient is instructed to let his jaw relax (palpate the temporalis
and masseter muscles to relax them), pull it back and close slowly
on the back teeth.
2.
The patient is instructed to get the feeling of pushing his upper jaw
out and then close the mouth with back teeth in contact.
3.
Assist the patient to protrude and retrude the mandible repeatedly
with the operator holding the finger lightly against the chin.
4. Boo's series of stretch exercise:
a- Open the mouth wide and relax.
b- Move the jaw to the left and relax.
c- Move the jaw to the right and relax.
d- Move the jaw forward and relax
Methods To Assisting Patients To Move The Mandible To The
Centric Relation
5. The patient is told to swallow and conclude the act with the occlusal rims in contact.
However, the person can swallow when the mandible is not completely retruded. This
method must be verified by other technique.
6. The patient can be instructed to turn the tongue towards the posterior border of the upper
record base and close the rims together until they meet. The disadvantage with this method is
the likelihood of displacing the mandibular record base by the action of the elevated tongue.
Methods To Assisting Patients To Move The Mandible To The
Centric Relation
7. Tilt the patient head back, the tension of muscles under chin make protrusion more
difficult.
8. Exert pressure in molars in both sides and ask the patient to close (molar reflex
method).
9. Celluloid strip is placed between the rims and pulled out. Ask the patient to restrain the
strip from slipping away; the mandible involuntarily goes to centric relation.
Establishing Maxillomandibular Relationships
Paralleling the Wax Rim to the Occlusal Plane
Determining the Rest Vertical Dimension (RVD
1
3
2
4
Index fingers on the rim,
thumbs under chin
mid line & canine
eminences
Check that record base heels
(rims do not touch).
depth 1-2 mm.
Too Shallow
1-2 mm
Aluwax
Keep Wax Neat
Hold position until set 1-2 minute.
Remove both rims together.
References