4- b Steps of recording jaw relation for completely edentulous patients

Dr. Amal Fathy Kaddah
Professor of Prosthodontics,
Faculty of Dentistry
Cairo University

Yesterday is gone
Tomorrow
has not yet come
We have only today
let us begin

jaw Relation
• A relation of the mandible to the
maxilla.
The Glossary of Prosthodontic 2005

Jaw Relation
Registration
For Completely
Edentulous Patient

RECORDING JAW RELATIONSHIPS
1. Check denture foundation.
2. Establish facial contour.
3. Establish occlusal plane.
4. Maxillary face-bow record.
5. Determination of vertical dimension of
centric occluding relation.
6. Determine centric and eccentric relations
at the accepted vertical dimension.
7. Locking device ( recording the C.O.R. )

Armamentarium
• Casts and Occlusion
Blocks
• Fox Plane, Rulers.
• Face Bow
• Fixed Condylar Path
Articulator
• Modelling Wax
• Wax Knife and carver
• Wall Paper Knife
• Gaz Torch

REQUIREMENTS
of OCCLUSION
BLOCKS

1- Rigid and strong to withstand the biting force.
2.Smooth and clean to avoid patient’s discomfort.
3. Fit the cast accurately.
4- Be dimensionally stable.
4- Stable inside the patient’s mouth.
6- Be of proper thickness (2mm on the palate &
less on the alveolar crest).
7- Be easily and quickly constructed.
Requirements:
They should :

Shellac Baseplate
Cannot withstand biting pressure and
body temperature. X X X X

Autopolymerising acrylic resin
It offers rigidity, close adaptation and
can withstand heat and pressure
without deformation.

Record Bases
•Free from wax,
•Stable, Adapted,
•Fitted, Retentive
•Well extended

• If loose >> Inaccurate record
and phonetic tests
• Use denture adhesive if slightly
loose
• Pronounced looseness
REMAKE
Fit the cast accurately
Requirements:

Record Base Retention
• Causes of Poor Retention
– Poor adaptation of resin to
cast
– Over- or under-extension
– Excessive block-out

Occlusion Rims
• Occlusion rims
slightly bulkier
• Provide
additional
stability during
record making

Maxillary Occlusion rim measurements
Width:
a- ant. = 4-6 mm
b-post. = 8-10 mm
Height:
a- ant. = 20-23 mm
b. post. = 16-18 mm

16 mm 23 mm
16 mm
Mandibular
Maxillary
2/3 Retro molar pad

Registering Centric Relation
Max & Mand
Occlusion Rims
– Two sharp “V”-
shaped notches in
the molar/premolar
area of each sided
wax
– Depth 1-2 mm
1-2
mm

Ensure Adequate Notch
Depth
Too Shallow
no undercuts

When the occlusal plane is located below the
greatest convexity of the tongue. The tongue tries
to seat the lower denture.

8-10 mm
4-6 mm
Width : ( U. & L. )
a- ant. = 4-6 mm
b- post. = 8-10 mm
Height
ant. = 16 mm
post. = 2/3 the retromolar
pad height
Mandibular Occlusion Rim Adjustment

Centered over the ridge to maximize stability

Maxillary and Mandibular
Occlusion Rim Adjustment
• Maxillary rim slightly
facial to compensate
for ridge resorption
• 1-2 mm horizontal
overjet in anterior &
posterior in centric
position.

I- Check Denture Foundations
• Extension
• Retention
• Stability

Establish the posterior palatal seal
• The outlines of the posterior palatal
seal (post-dam) and relief areas
should be marked with a lead pencil.
• The entire post-
dam area has
been excavated.
In V-shaped cross-
section.

II-Establish Facial Contour
• Teeth position or wax rim supports
facial musculature and appearance.

X
Support Assessment.
Unsupported lip.

• Lips should be unstrained
• Philtrum
• Vermilion border showed
• Naso-labial angle ≈ 90°

5. Determination of vertical dimension of centric
occluding relation.
6. Equalize pressure of occluding forces.
7. Determine centric and eccentric relations at the
accepted vertical dimension.
8. Locking device ( recording the C.O.R. )

A common plane
established by the incisal
edges and occlusal
surfaces of the teeth.
[This is usually curved and
is therefore not strictly a
plane]
III- Determination of the occlusal plane

Determination of the occlusal plane
• Aesthetic base.
• Functional base.
• Mechanical base
(Denture stability).

Maxillary Occlusion Rim Adjustment
• Anterior height
1-2 mm below
the lip at
rest/when the
patient slightly
smiles

Wax rim/tooth
display can be
adjusted with
sex, age, and
lip length

10-20mm 3-4mm
20-25mm 2mm
26-30mm 1mm
>30mm 0
Lip Length Incisal Display
Female Male
Young +2 +1
Middle +1 0
Old 0 -1
Sex & Age

• Touches wet line of lower lip
when ‘F’ or ‘V’ sounds
• Count ‘50-60’

The wax rim should be
trimmed with a knife so
that the occlusal plane
is roughly parallel to the
reference plane

• The heated plate should be lightly pressed
onto the roughened surface to level it
• The rim must be placed on the cast to avoid
deformation of the baseplate and the occlusion rim.

Anterior occlusal plane
Parallel to interpupillary line.

Posterior occlusal plane
Parallel to the ala tragus line.

It is advisable to use an occlusal plane
indicator use of FOX occlusal guide for
obtaining the correct anterior and
anteroposterior planes.

The high lip line This is a line just contact
with the lower border of the upper lip when it
is raised as high as possible unstrained, as in
smiling or laughing.

• Unstrained lips
• Vermilion border showing

• Posteriorly, the
occlusion rim
intersects 1/2 - 2/3 up
the retromolar pad
• The upper border of the
mandibular wax rim
should be even with
the upper margin of the
lower lip when the
patient slightly opens
his/her mouth

• Anterior height even with the
corners of the mouth when the lip
is relaxed

• 1-2 mm
horizontal overjet
in anterior &
posterior in
centric position

5. Determination of vertical dimension
of centric occluding relation.
6. Equalize pressure of occluding forces.
7. Determine centric relation at the
accepted vertical dimension.
8. Locking device ( Recording the C.O.R.)

Mounting the upper cast
1.By face bow record.
2.By Bonwill triangle.

TYPES OF FACE-BOWS
1. Mandibular or kinematic face-bow (hinge axis
face-bow). This locates the exact axis of
rotation of the condyles.
2- Maxillary face-bow
a. Kinematic facebow used to locate and
transfer true hinge axis.
b. Arbitrary face-bow This relates the maxilla to
the exact or arbitrary position of the condylar
axis and transfers this relationship to the
articulator.

Facebow record and Transfer
• Establishes the
relationship between the
maxillary arch and the
horizontal plane.
• Transfers this
this relationship
to the articulator.
Maxillary Face bow

Hinge Axis Location
• Face-bow or
ear-bow used
• Record relationship
of maxilla to
transverse
horizontal hinge
axis of mandible

Purpose
• To accurately mount the
maxillary cast to articulator
The facebow record transferred to
the articulator Important to prevent
occlusal errors

What if patient doesn’t match
articulator?
Articulator
Patient

Articulators
We obtain a measurement of this distance
with a facebow
aha
mha
occlusal errors
The lnterocclusal wedge space will not be equal

• Therefore the distance from the condyle to
the teeth is crucial, we obtain a
measurement of this distance with a
facebow

Face-bow Function
• Duplicates opening and closing arc of teeth
by relating maxillary arch to the hinge axis.
• Slight change of vertical dimension doesn’t
affect the relation

The first part of the
posterior border
opening is a rotation
around the hinge axis.
If the terminal hinge axis is recorded on
the articulator using a hinge face-bow, then
minor changes in the vertical dimension
will not alter the horizontal jaw relation.

In summary
The face bow records not only the radius
from the condyles to the incisal contacts of
the upper central incisors but also the
angular relationship of occlusal plane to the
axio-orbital plane, face bow must be
positioned on the articulator in the same
axio-orbital relation as on the patient.

In summary
Face bow must be positioned on the
articulator in the same axio-orbital relation as
on the patient. By the add of anterior
reference points
Nasion support

IV- Establishing
Occlusal Vertical Dimension
and Hinge Axis Relation

Occlusal Vertical Dimension (OVD)
• Distance between maxilla
& mandible when teeth or
wax rims contact in
centric position
• Amount of separation
between mandible &
maxilla when denture
teeth are in contact

a- Patient sitting bolt upright
VDO measurement affected by posture

Measuring Occlusal Vertical Dimension
• Measure the distance between dots
– At VDR
– At VDO
– Difference is IOS
Inter Occlusal Rest
Space
Measurements change each day (position
of dots)

Physiologic Rest Position
(PRP)
• At rest, lips barely
touching
• Occlusion rims
should not touch
Intraorally no contact

Interocclusal Distance (ID)
• Space between wax rims at
physiologic rest position
• Usually 2-4 mm

Measurements OVD & PRP
• Use external points for
ease of measurement
• Small dots under
columnella & mid-
symphisis
• Use Boley Gauge, not
ruler

Measuring Occlusal Vertical Dimension
• Open and close until rims
touch
• Measure distance between
dots (OVD)
• Measurement will be
different each appointment

Establishing OVD
Feeling for Interocclusal Distance
• Close until lips barely
touch - PRP
• Place finger on chin
• Look away
• Patient closes until rims
touch (OVD)
• Feel for movement of the
mandible

Establishing OVD Phonetics Test
• Closest Speaking Space
• Confirms OVD
• Sibilant sounds ("s", "z", sh", ch")
• Rims should be at least 1 mm apart
• Don’t worry about sounds yet

Excessive OVD Wax Rims Too High
•Insufficient interocclusal distance
•Remove wax from one or both of the rims
– Use large wax formers
– #5 & #7 wax spatulas
– Red-handled knife
– Bunsen burner and torch

Wax Rim Adjustment at OVD
• Flat even contact along
entire occlusal surface
• If uneven contact,
patient may be forced
into eccentric position

Adjusting Wax Rim Height
• Scribe lines parallel to the
opposing occlusal rim
• Use as a
guides during
reduction

Eliminating Record Base or Wax Rim
Interferences
• Patient in Centric
Position
• Scribe three widely
separated lines
between maxillary &
mandibular rims

1- Central line (midline)
2- The corner line (canine line)
3- The high lip line and low lip line

Establishing OVD
• Remove, superimpose
the lines
• Eliminate contacts
between record bases,
record base/occlusion
rims

Adjusting Occlusion Rims
• Continue to adjust the rims until:
– Interocclusal distance is 2-4 mm
– Even contact along rims in centric
position.

Excessive Occlusal Vertical
Dimension
• Sore muscles
• Soft tissue sore spots
• Rapid bone resorption
• Dentures click during
speech

Inadequate Occlusal Vertical
Dimension
• Collapsed Appearance -
chin too close to the
nose or protruding jaw
• Fatigue when chewing
• Sore muscles or joints

• Transferred to the articulator
• Important to prevent occlusal
errors, particularly when
cusped teeth are used in
dentures.
Hinge Axis Location

Edentulous Bite Fork:
Allows patient to close
against the opposing rim
to stabilize the record
bases

Heat bite fork and imbed
it centered and parallel
the occlusal plane

Finger cots can be
used over ear pieces
for infection control
Patient can assist
with placement and
orientation in external
auditory meatus

Orient in external
auditory meatus

Slide facebow onto
bitefork
Extend nasion
support& tighten

Tighten center
facebow screw
Set and tighten
nasion nosepiece

Ball correctly placed inside slot will ensure full
range of anterior/posterior
movement of the toggle assembly
Ball placed in slot

Release the record base
by breaking the seal, and
removing the facebow.
Attach the Quick Lock
Toggle Assembly to the
bite fork.
Tighten the Quick Lock
Toggle

Loosen and remove
the transfer jig
from the earbow

Place facebow support on
transfer jig and attach to
indirect mount.
Don’t use direct method
with indirect mount.

Remove incisal pin
and set the centric
latch
Ensure front support
on your articulator

Indirect jig with record
base on articulator

Place cast support
and maxillary
mounting plate

Attach cast with
mounting plaster in
two steps

4- b Steps of recording jaw relation for completely edentulous patients

4- b Steps of recording jaw relation for completely edentulous patients

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