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7/16/2019 12. Centric & Protrusive Record
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Robert W. Loney
Maxillo-Mandibular Relationships
Centric and Protrusive Records
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Robert W. Loney
Problems Establishing Edentulous
Maxillo-mandibular Relationships
Edentulous patients have moredifficulty determining where theirdenture teeth should contact No periodontal membrane
Old dentures wont fit on casts
Record base fit and wax rim changes
confuse some patients
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Robert W. Loney
Centric Position
Acceptable position should be:
Conducive to health
Relatively repeatable
position can be checked before dentures
completed
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Robert W. Loney
Conducive to Health
Relatively Symmetrical Position
Not absolute symmetry
Less chance of muscle strain which
might occur in non-centered positions
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Robert W. Loney
Hinge Position is Repeatable
relatively centered
patient can find stable
occlusal contactsrelatively easily
allows change in
vertical dimension
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Centric Relation (CR) Centric position of mandible in
relation to the maxilla
Defined by the position of thecondyles, rather than the teeth
Hinge position
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Centric Relation
Treatment position
Not necessarily ideal ornormal
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Centric Occlusion (CO) Maxillo-mandibular position
determined by teeth
Sometimes considered coincident with
maximum intercuspationor habitual
closure
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CRand CO have been defined
differently by various
investigators, and differently overdifferent time periods
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Where is Centric Relation?
Glossary of Prosthodontic Terms:
Independent of
tooth contact
Clinicallydiscernible when
the mandible is
directed
superiorly andanteriorly
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Where is Centric Relation?
Glossary of Prosthodontic Terms:
Condyles articulate with thinnest, avascular
portion disks
Anterior-superior position against slope of the
articular eminence
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Where is Centric Relation?
Glossary of Prosthodontic Terms:
Purely rotary
movement
about thetransverse
horizontal axis
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For the purpose of fabricating
complete dentures, the superior-
anterior position of Centric Relationwill be used
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Robert W. Loney
Clinically the dentist cannot
determine the actual position of the
condyles at the time jaw relationsrecords are made
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When to Use Centric Relation
When entire occlusion being restored
No remaining posterior centric stops
When complete, fixed, or removable
partial dentures involve the entire
occlusion
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When to Not to Use Centric
Relation Stable occlusion
No pathology
Posterior centric stopspresent
No valid reason to change
Use maximum intercuspation
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Registering Centric Relation
Bimanual manipulation
Patient in a slightly
supine position
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Registering Centric Relation
Bimanual manipulation
Occlusion rim notched
to aid stabilizing the
record bases
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Registering Centric Relation
Bimanual manipulation
Index fingers on the rim,
thumbs under symphysis
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Registering Centric Relation
Jiggle the mandible
Mandible should freely arc Allow the patient to close into contact
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Robert W. Loney
Registering Centric Relation
Do NOT push the mandible or
dislodge the record base
Medium must be dead soft
(Yurkstas and Kapur)
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Registering Centric Relation
Minimal closing pressure
(Yurkstas and Kapur)
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Recording Centric Position
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Preparing Occlusion Rims
Place 3 widely separated lines between
the rims in the centric position
CRITICAL! Check that record base
heels/rims do not touch
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Line up Marks
Eliminate contact with record
bases
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Registering Centric Relation
Max & Mand Occusion Rims
Two sharp V-shapednotches in themolar/premolar area ofeach sided wax
Depth 1-2 mm
1-2mm
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Ensure Adequate Notch Depth
Too Shallow
- no undercuts
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Registering Centric Relation
Rehearse making the record withoutrecording medium
Place occlusion rims intraorally PVS registration material (Memoreg) over
entire occlusal rim
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Thin Layer of Material
Too Thick Good
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Thin Layer
Want flat record, no
excess on sides of rims
Excess material recording
of the sides of the rim can
cause deflection when
checking record
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Making the Record
Have patient close into record
Ensure smooth arc of closure, nohorizontal deviations
Use index fingers to stabilize lowerrecord base
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Registering Centric Relation
Patient opens, relaxes,
and slowly closes
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Registering Centric Relation
Gently arc the mandible in
a hinge-like motion
There should be: No translation
No splinting
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Registering Centric Relation Patient slowly closes
Operator uses tactile senses to
ensure the mandible does not
translate
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Registering Centric Relation
Patient closes until rims are almost
touching (1 mm separation)
Ask patient to stop as soon as thisposition has been reached
Some may not be able to tell when
they contact
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Registering Centric Relation
Never instruct the patient to bite
firmly
Causes translation or inaccuracyin the record
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Registering Centric Relation
Hold position until
set 1-2 min
Remove both rims
together
Separate
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Registration Should be Sharp,
Not Rounded
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Registering Centric Relation
Mounting the Mandibular Cast
Ensure record is repeatable
Increase the height of incisal
pin 1 mm, invert articulator
Place wax rims together, lute
with sticky wax - 4 spots
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Registering Centric Relation
Mount the mandibular cast withmounting plaster
After mounting, remove the record &
adjust the incisal pin to allow contactbetween rims
Occlusion rims should be touchingevenly, over the entire occlusal surface
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Registering Centric Relation Do not alter incisal pin after
rims are contacting
Otherwise, height of correct
vertical dimension can be lost
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Check CR Record
Take new record, place onarticulator
Release articulator centric locks
Should arc into record without anytranslation
If doesnt take 3rd record to see
which one is reproducible
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Protrusive Records
Used to set
condylar guidance
Helps setting teethfor best occlusal
contacts
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Protrusive Records Protrude a minimum of 5-6 mm
Ease of determination
Protrude less than 12 mm
Maximum travel of the condylar element
on most articulators
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Protrusive Records
Registration material over entire
rim Patient closes with mandible
positioned anteriorly
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Protrusive Records
Material must interdigitate with the
opposing V-shaped notches
Record should cover entire rim surface
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Protrusive Records Condylar elements are released from
hinge position
Instrument protruded, and the rims
closed into record
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Adjust Protrusive Guide for
Maximal Interdigitation
S tti C d l A l
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Setting Condylar Angle
QuickTime and a
H.263 decompressorare needed to see this picture.
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Protrusive Records
The lateral
component of
condylar guidance(Bennett Angle)
can be set
arbitrarily at 15
Maxillomandibular Records
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Robert W. Loney
Maxillomandibular Records
for Complete Dentures
Centric Relation
Treatment position
Operator assists to ensure a hinge position
Patient stops closure at initial contact
Protrusive
Programs articulator to optimize occlusion