12.surveyed crowns and combined fixed rpd cases

12. Surveyed Crowns and
Combined Fixed RPD Cases
Aria Davodi DDS
Ting Ling Chang DDS
John Beumer III DDS, MS
Division of Advanced Prosthodontics, Biomaterials and
Hospital Dentistry
UCLA School of Dentistry

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Surveyed crowns and combined fixed RPD cases

Varies from extensive
rehabs to when the fixed
is confined to abutments
associated with the
RPD.

Surveyed crowns and combined fixed RPD cases

Varies from extensive rehabs to when the fixed is
confined to abutments associated with the RPD.

When Does One Choose to Fabricate a Crown to Serve
as a Removable Partial Denture Abutment?
v  Whencorrection of
unacceptable tooth
contours cannot be
achieved through
enamel modification
alone

When does one choose to
fabricate a surveyed crown
v  To restore a badly broken down clinical
crown
v  To reestablish a proper occlusal plane
(i.e. supra-erupted teeth
v  To create proper rests, particularly with
anterior teeth, and adequate retentive
undercuts for direct retainers (I-bar, C-
clasp) and guide planes when
inadequate contours exist.

Objectives of Modifying Abutment Tooth
Contours
v  Develop an acceptable path of
insertion for the RPD
v  Promote favorable
biomechanical properties.
v  Retention
v  Stability
v  Support
v  Improve Esthetics

Stability
Support

Retention

Combining Fixed Restorations and Removable
prostheses--Treatment Sequence
Diagnosis Determine that a surveyed crown or crowns
are needed

RPD design is based on support,
Design stability, and retention

Fixed Restorations

Removable
Prostheses

Surveyed Crown Fabrication--Treatment Sequence
v  Mount study casts with a facebow record and preferably
in centric relation
v  Fabricate treatment RPD’s as necessary
v  Surveyed diagnostic wax-up with guide planes and
occlusal rests
v  Duplicate diagnostic wax-up and generate a stone cast
v  Fabricate preparation guides
v  Prepare and temporize abutments
v  Prepare guide planes and rest seats on other RPD abutments
based on the established RPD design
v  Adapt treatment RPD’s
v  Final FULL ARCH impression
v  Obtain facebow record to mount maxillary cast*

Surveyed Crown Fabrication--Treatment Sequence

v  Make centric relation or maximum intercuspation record to
mount the mandibular cast*
v  Record bases fabricated if inadequate number of teeth remain
v  Survey full contoured crown wax-up including all RPD
components
v  Wax cut back if metal PFM restoration
v  Cast, fit to die, metal try-in to verify fit of casting, occlusion if
applicable
v  Porcelain bisque survey, and try-in – verify interproximal
contacts, occlusion, fit, guidance, esthetics
v  Porcelain glaze, and final cementation
v  Refinement of other RPD abutments (guide planes, rest
seats, facial / lingual heights of contour for retainers) and final
RPD framework impression
v  Finish the RPD in the usual manner

Treatment RPD’s
Patient presents with:
v  Missing posterior occlusion
v  Moderate wear with reduced vertical dimension of
occlusion
v  Unfavorable tooth contours for RPD Support and
retention

Surveyed Crowns -Treatment Sequence
v  Mount study casts with a facebow record
preferably in centric relation
v Case should be mounted at the proper vertical
dimension and when necessary using record
bases and wax rims.

Surveyed Crowns -Treatment
Sequence
v Forfixed and removable
combination cases always come
up with the RPD design during the
diagnosis & treatment plan
appointment
v Survey and determine the MAP
for RPD

Surveyed Crowns -Treatment
Sequence

v  Forfixed and removable combination cases always
come up with the RPD design during the
diagnosis & treatment plan appointment
v  Survey and determine the MAP for RPD

Treatment RPD’s – Purpose
v  Replace missing teeth
v  Establish posterior occlusion
v  Test changes in vertical dimension
v  Trial prostheses—See if patient can adapt
to removable prostheses

Treatment Partials
Note occlusal platform on
maxillary treatment partial
to restore patient’s vertical
dimension

Surveyed Crown Fabrication
Pre-clinical Diagnostic procedures
Perform a diagnostic wax-up
of teeth that are to receive
surveyed crowns
v  Surveyed diagnostic wax-up with
guide planes and rests
v  Correct tooth angulation problems
v  Correct occlusal plane problems
v  Determine the proper path of
insertion of the eventual RPD by
surveying the wax-up. Carve rest
seats, guide planes, and heights
of contour for your retainers(I-bars,
C-Clasps) in wax.

Diagnostic Wax-up
v Full contoured wax-up is performed for teeth
that are to receive crowns

• Carve rest seats,
guide planes, and
Rests carved in wax. heights of contour for
(Additional tooth reduction will be your retainers (I-bars,
required in these areas) C-Clasps) in wax.

Diagnostic Wax-up

v Set the denture teeth and establish the desired
occlusal plane
v Scheme of occlusion based on the situation
existing in the weakest arch.

Pre-clinical Diagnostic procedures

v  Duplicate diagnostic wax-up
by making an alginate
impression and pouring a
stone cast.
v  Fabricate preparation guides
v  Vacuum formed matrix (suck-
down) to serve as a tooth
preparation guide and a matrix
to fabricate a provisional
(temporary) restoration.

Preparation guides
This type of guide is useful when preparing fixed
preparations so that all the guide planes of the finished
restorations will be parallel to one another.

Preparation guides

v Prepare
the guiding surfaces on all RPD
abutment teeth before beginning any restoration
v Then the preparation for the restoration can
begin following the MAP

Tooth Preparation and Provisionalization
New treatment partials were fabricated to fit provisional
restorations

restorations
Before provisionals

After provisional

restorations

Before
After

Surveyed Crown Fabrication---Tooth
Preparation, Impression Making
v  Full arch impression
v  Send case to laboratory to pour, pindex, separate from base.
v  Ask laboratory not to section between preps, or trim your dies
and return your master cast for record base fabrication and
mounting of the case.

Master cast
Final FULL ARCH impression Base

Surveyed Crown Fabrication---Mounting Casts

l  Fabricate record bases
l  Add wax rim
l  Determine vertical dimension of occlusion.
l  Determine anterior tooth position and proper
lip support
l  Establish occlusal plane
l  Mount the maxillary cast with a facebow
transfer and the mandibular cast with a
centric relation record.

Record bases
fabricated on
master casts

Wax-rims added

Determine VDO, occlusal plane, proper anterior tooth display
and lip support clinically. Mount maxillary cast with facebow
transfer record and mandibular cast with a centric relation record

• -Set teeth
• -Confirm vertical dimension
• -Determine proper tooth
position,
• -Verify mounting
• -Begin surveyed crown
fabrication

Surveyed Crown Fabrication – Laboratory Procedures
1.  Set adjacent and opposing teeth
2.  Trim dies
3.  Perform a full contoured wax-up. Place on
surveyor, establish path of insertion (MAP),
carve rest seats, guide planes, Facial, lingual
heights of contour for direct retainers (I-bars,
C-Clasps) and reciprocating arms or elements
(i.e. minor connectors, proximal plates, partial
lingual plates.)
4.  Perform wax cut back for porcelain fused to
metal (PFM) restorations.
5.  Sprue, invest, cast, divest crown. Fit crown to
die
6.  Perform a metal try-in if applicable

Survey master
cast to determine RPD
path of insertion (MAP),
tripodize cast

Perform a full contoured wax-up according to your MAP, determine
occlusion (set adjacent and opposing teeth)
Guide planes and rests should be
in metal

Maximize guide plane
height and width to Survey for tissue undercuts on Positive cingulum
optimize stability a solid model to aid in retainer rest
design
Cut back wax-up for PFM fabrication. Maximize height and width of
Guide planes to enhance RPD stability, make sure rests are positive.

Surveyed Crowns

v Perform metal try-in
v Why?

Why Perform a Metal Try-in?
l  Determines whether your
master impression was
accurate prior to porcelain
application
l  Determines marginal fidelity,
retention, resistance form of
your restoration
l  Determines the accuracy of
your occlusion and
interproximal contacts in full
metal restorations
l  Determines the proper fit
(without rocking) of splinted
crowns and bridges

Surveyed Crown - Porcelain Bisque Try-in

v  Bake porcelain. Place on
surveyor to establish
contours based on the
RPD’s path of insertion
(MAP).

v  Place crowns on a solid
master cast (dies not
trimmed) to evaluate tissue
contours, survey, make all
changes in porcelain.

Surveyed Crown - Porcelain Bisque Try-in
l  Survey master cast, reestablish
determine most advantageous
position (MAP)
l  Adjust guide planes, buccal and
lingual contours to optimize
parallelism and undercuts for
direct retainers (I-bars, C-
clasps)
l  Make sure all rests are positive.
Be careful not to perforate rest
seats while adjusting. Measure
depth of metal with calipers.
Minimum metal depth should be
0.5 mm.
l  Refine occlusion

Surveyed Crown Fabrication Porcelain Bisque Try-in
Use carbides or stones to adjust metal, diamonds to adjust
porcelain. Polish all adjustments with silicone carbide wheels.

Long, wide guide planes maximize
Note the perfect location for I-bar. 0.01” stability, and minimize tissue
undercut at the cervical 1/3 of crown hypertrophy under RPD frame.

Completed Crown Check List
v Parallel Guiding Surfaces
(in metal)
v Positive rests
v Retention in the cervical one
third of the tooth

Porcelain Bisque Try-in
Take to mouth for try-in.
v  Check interproximal
contacts
v  Check Margins

v  Check Occlusion

v  Check Shade

Final Delivery
After all adjustments are
completed:
v  Glaze Porcelain
v  Polish Metal
v  Cement Crowns
v  If treatment partials present,
plan for their adjustment to fit
around new crowns
v  Make final RPD impression in
alginate capturing all soft tissue
(denture bearing surfaces)
detail.

RPD Framework Fabrication
Alginate impression for RPD framework
must capture all tissue detail

Retention in
The retromolar pads cervical third
and the retromylohyoid
area have been
captured in the alginate
impression Long, parallel
guide plane
Once happy
with the RPD’s
path of
insertion,
tripodize cast

RPD Fabrication
v  Framework design
v  Write laboratory work authorization, send case to lab
for framework fabrication
v  Try RPD framework
v  Make sure it is fully seated
v  Physiologic adjustment
v  Adjust occlusion
v  Altered cast impression in extension base RPD’s
v  Fabricate record base, wax rim, mount case
v  Set denture teeth
v  Tooth try-in clinically
v  Verify mounting
v  Verify esthetics
v  Process and delivery

Physiologic Adjustment
Method
v  Dissolve gold rouge with chloroform
v  Apply this solution to the surfaces engaging the teeth of the RPD casting.
The chloroform will quickly evaporate, leaving a thin layer of rouge on the
casting
v  The RPD casting is seated and pressure is placed on the extension area
v  The rouge will be rubbed away from areas of the casting that are
inappropriately binding to the dentition.
v  These areas are relieved with a suitable burr and a high speed air rotor
v  The procedure is repeated until the framework rotates freely around the
axis of rotation

Physiologic Adjustment
Method
v  When the procedure is complete the RPD framework will
rotate freely around the axis of rotation with out lifting out of
the rest seats that determine the axis

Altered Cast Impressions
For extension base RPD’s

RPD Fabrication is completed in the usual way
v CR records
v Set teeth
v Occlusion based on the weakest arch
v Esthetic try in

RPD Occlusion
Based on the weakest arch
v  One arch edentulous – Bilateral balanced
occlusion
v  Both arches partially dentate – Anterior
guidance or group function

Bilateral balance Anterior guidance

Delivery sequence

v  Seat dentures using PIP
v  Verify extensions with periphery wax
v  Adjust occlusion following clinical remount.
v  Followup instructions

Case presentation
Patient presents with:
v  Missing posterior occlusion
v  Reduced vertical dimension of occlusion
v  Moderate attrition
v  Unfavorable tooth contours for RPD Support and retention

v Final FULL ARCH Impressions
v Master casts pindexed, bases to be poured
v Case to be mounted using record bases and wax rims

Metal Try-In

Porcelain Try-In

RPD Fabrication is completed in the usual way
v Altered cast impressions
v CR records
v Set teeth
v Occlusion based on the weakest arch
v Esthetic try in

Surveyed Crown/Bridge Delivery
Make sure all cement is Note POSITIVE
removed cingulum rests

Final Result
Before

After

Case presentation

l  Patient
presents S/P resection of the soft
palate for a squamous carcinoma

Surveyed Crowns
RPD framework

Surveyed Crowns

v  Completed RPD with obturator prosthesis
v  Note there are only two direct retainers
v  Enhancement of vertical support is provided by
the engagement of the root of the right cuspid

Surveyed Crowns

v  Patient presents status post
resection of right posterior alveolar
ridge and soft palate for a
squamous carcinoma
v  Preparations have made for
surveyed crowns
v  The metal work is tried in to verify
marginal integrity and occlusion

Surveyed Crowns

v  Porcelain is added and the restorations
are cemented
v  Impression is made in preparation for
fabrication of the RPD framework

Surveyed Crowns

RPD design and completed framework
v  Note the bracing via the lingual plate. This is required
because of the lateral forces applied to the obturator
extension during speech and swallowing.
v  The long length of lever arm of the soft palate
obturator will increase the magnitude of the forces,
hence the need for increased bracing

Surveyed Crowns

RPD design and completed framework
v  Note the cingulum rests on the cuspids and the mesial
rest on the right premolar
v  There are only two direct retainers
v  Note the fulcrum line. Indirect retention is provided by the
rests on the left cuspid and premolar and the lingual plate

Surveyed Crowns

v  The RPD framework is tried in and physiologically
adjusted
v  An altered cast impression of the residual alveolar
ridge and soft palate defect is obtained with
compound and a thermoplastic wax

Surveyed Crowns

v  The
completed
prosthesis

12.surveyed crowns and combined fixed rpd cases

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