Transcript Jaw Relation Records & Techniques for RPD - Home

Jaw Relation Records & Techniques
for RPD
McCracken's RP Prosthodontics;
Stewart’s Clinical RP Prosthodontics.
Why to Record the Jaw Relations ?
•To establish and maintain a harmonious
relationship with all oral structures and to
provide a masticatory apparatus that is efficient
and esthetically acceptable.
• To ensure that all the effects of occlusal loading be
distributed as evenly as possible to all supporting
structures capable of receiving the force.
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.
Jaw Relation Records – A Review
• Vertical Jaw Relations:
Rest Vertical Dimension ‘RVD’
Occlusion Vertical Dimension ‘OVD’
• Horizontal Jaw Relations:
Centric Relation
Centric Occlusion
Eccentric Relations
Protrusive relation
Lt & Rt Lateral relations
• Face bow Registration.
Vertical Jaw Relation
The vertical distance between
two selected points, one on
the fixed (maxilla) and one
on the movable member
(mandible).
Vertical Jaw Relations
Rest Vertical Dimension ‘RVD’
Occlusion Vertical Dimension ‘OVD’
Inter-occlusal Distance / Free way Space
Vertical Jaw Relations
Rest Vertical Dimension (RVD)
Is the distance measured when
the mandible is in the rest
position.
Occlusal vertical Dimension (OVD)
Is the distance measured when
the occluding rims or teeth are in
contact.
Inter-occlusal Distance
The distance between the occluding surfaces of maxillary and
mandibular teeth when the mandible is in the rest position.
For a complete denture patient, it is the difference between
RVD and OVD.
RVD – OVD = 4 mm
or
RVD – 4 mm = OVD
Inter-occlusal Distance
In natural dentition it ranges from 2-4 mm in the premolar
area - the Freeway Space.
Vertical Jaw Relations
If stable occlusal contacts are provided by the remaining natural teeth,
the existing OVD and CO relation should be recorded.
For the patients whom one of the arch is edentulous or whom the
opposing teeth do not provide stable occlusal contacts, OVD has to
be measured as follows,
RVD – OVD = 3 - 4 mm
Altering the Existing OVD
Normally the OVD of a partially edentulous patient
is provided by the opposing natural teeth contact
and it should not be changed.
Unless,
Altering the Existing OVD
1. Symptoms of diminished OVD exist such as tired aching muscles,
unexplained pain in the head and neck region, shortened nose-chin
distance (appearance of premature aging).
2. Excessive Free way Space or ‘over-closure’ of the jaws.
Altering the Existing OVD
Wearing of the teeth does not mean that OVD should be increased –
unless the free-way space is greater than 4mm.
How to alter the existing OVD
1. Confirm the loss of vertical dimension by taking history, cephalometric
examination, and the presence of excessive free-way space.
2. Increase the existing OVD temporarily by fabricating an acrylic resin
occlusal overlay appliance in maximum intercuspation, ensuring that
4mm of freeway space must exist.
How to alter the existing OVD
3. Restore the desired OVD permanently with the help of fixed and
removable prosthesis (made simultaneously) only after the
physiologic response of the patient to this appliance is positive.
Altering the existing OVD - a case report
Altering the existing OVD – a case report
Horizontal Jaw Relation
Centric Relation
‘the most retruded position of the mandible to maxilla at an
established OVD’.
It is a bone to bone relation that is repeatable by the patient. It
remains constant throughout life & during its recording cuspal
relation of the teeth is not considered.
Horizontal Jaw Relation
(Centric Relation)
The maxillo-mandibular relationship in which the condyles articulate
with the thinnest a vascular portion of their respective disks, with
the complex in the anterior-superior position against the slopes of
the articular eminences.
To record this position, the mandible
is directed superiorly and anteriorly
restricted to a purely rotary movement
about a transverse horizontal axis.
Horizontal Jaw Relation
Centric Occlusion
‘the relation of the mandible to maxilla in the maximum
intercuspation of the teeth’.
It is a tooth-tooth relation - a position of habitual closure.
Horizontal Jaw Relation
What to Record – C.R or C.O
In more than 90% of people, C.O is 0.1 - 2mm in front of the CR.
Horizontal Jaw Relation
What to Record – C.R or C.O
Centric Occlusion should be recorded whenever a patient requiring
a partial denture has cusps on remaining natural teeth that can guide
the mandible back to this position,
otherwise,
Horizontal Jaw Relation
What to Record – C.R or C.O
C.R should be recorded, e.g., for distal extension RPD, or when the
opposing arch is edentulous.
Methods of Establishing Occlusion for RPD
Articulator or Static Technique
This method of formulating occlusion cannot be used
without first clinically establishing the occlusal
relationship of the jaws - by using record bases and
occlusion rims attached to the RPD framework.
Methods of Recording Jaw relations:
Direct Apposition of Casts (Hand Articulation).
Use of Record blocks attached to the Framework.
Methods of Recording Jaw relations
Direct Apposition of Casts
(Hand Articulation)
This method can only be used when sufficient opposing teeth
remain in contact to make the existing jaw relationship obvious.
Methods of Recording Jaw relations
Direct Apposition of Casts
(Hand Articulation)
The occluded casts are secured together with the help of wooden
sticks and sticky wax and mounted arbitrary on an articulator.
A face-bow record may also be used.
A clinical appointment is saved by using this method.
Methods of Recording Jaw relations
Record Blocks attached to the Framework
Recording jaw relations clinically are essential when,
a. the remaining dentition does not provide sufficient occlusion.
Methods of Recording Jaw relations
Record Blocks attached to the Framework
b. one of the arches is edentulous.
Methods of Recording Jaw relations
Record Blocks attached to the Framework
Making the Record Block:
After carefully verifying the
fit and occlusion of the RPD
framework intra-orally and after
performing the altered cast
procedure, an auto-polymerizing
acrylic resin base is usually
attached to the framework saddle
areas. A base-plate wax base
may also be formed.
Methods of Recording Jaw relations
Record Blocks attached to the Framework
A wax occlusion rim is then
placed over the resin base, while
considering the width and height
dimensions of the natural missing
teeth.
Methods of Recording Jaw relations
Clinical Procedure:
1. The framework with the attached record block is first tried in the
mouth for reconfirming the fit of framework.
2. The height of the wax occlusion rims are so adjusted intra-orally that
1mm of space exists between the opposing teeth & the rims. For
two opposing rims, occlusal plane is adjusted on one of the rims,
e.g., mandibular distal extension wax rim.
Methods of Recording Jaw relations
Adjusting the Occlusion rim
Methods of Recording Jaw relations
Adjusting the Occlusion rim
Additionally, adjusting the Occlusal Plane of the remaining natural teeth
may also be indicated by ‘Enameloplasty’
Methods of Recording Jaw relations
Adjusting the Occlusion rim
Methods of Recording Jaw relations
3. The recording medium (wax or ZnO paste) is then placed on the
mandibular wax rims while V notches are cut in the upper rim the patient is then guided in the desired C.O or C.R position.
Methods of Recording Jaw relations
Methods of Recording Jaw relations
Identify An Inaccurate Record
Methods of Recording Jaw relations
4. Care must be taken to avoid any pressure being applied on the soft
tissue under the record bases to avoid any inaccuracies.
Methods of Recording Jaw relations
Any pressure applied during recording the jaw relations will result in
inaccurate mounting.
5. A face-bow record should also be taken for mounting the casts
accurately.
The Face-bow / Ear-bow
is an instrument used to record the spatial relationship of the maxilla to
some anatomic reference (transverse horizontal axis) and then
transfer this relationship to an articulator.
The registration obtained by means of a face-bow is called
a
“face-bow record”.
Why Use a Face-bow
To relate the maxillary cast to the condylar
elements of the articulator at the same
orientation that the maxillary teeth have to the
mandibular condyles of the patient.
As the teeth move during opening, closing, and
lateral movements, the arc of closure of the
teeth on the articulator and the patient’s mouth
should remain identical to avoid any occlusal
premature contacts.
The length of this arc is measured from the center
of the condyle to the incisal edge or the cusp of
the teeth.
As this record mounts the casts at the same
angulations as the jaws are related in the mouth,
the artificial teeth being placed on the cast can
be visualized as they will actually look in the
mouth.
How to Use a Face-bow
The steps of making this record can vary depending on the
type of face-bow & articulator being used, however,
following are the basic steps,
1. Preparation of the face-bow / bite fork.
How to Use a Face-bow
Locating the ‘arbitrary’ Hinge Axis:
Place an indelible pencil mark 13 mm in front of the posterior margin
of the tragus of the ear, on a line between the tragus of the ear to
the outer canthus of the eye.
How to Use a Face-bow
2. Orientation of the face-bow to
bitefork & reference points.
How to Use a Face-bow
The reference points for this
orientation may differ
depending on the types of
face-bow being used.
How to Use a Face-bow
Use of a Hinge axis Locator
Obtaining & Transferring the Face-bow Record
3. Orientation of face-bow to articulator.
Obtaining & Transferring the Face-bow Record
4. Mounting the maxillary cast to articulator.
Use of an Ear-bow
Use of an Ear-bow
Thank you