Fabricating Provisional Restorations

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Fabricating Provisional Restorations

• Dr Saj Jivraj DDS, MSEd Dr TJ Ahn DDS

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Indirect Technique

• Advantages
• Strength
• Fit
• Biocompatibility
• No lock on
• Can be delegated to auxiliaries.

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Indirect Technique
Take alginate impression of equilibrated
typodont, pour in die keen or yellow stone
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Ensure all positive defects are removed (bubbles)
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Ellman Pressform Kit
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Place a sheet of plastic from the Ellman kit in
the holding frame
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Spray both sides of the Ellman sheet to prevent
plastic from adhering to stone cast.
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Spray stone cast
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Manipulate the Ellman putty in your hand, as the
temperature of the material increases it will
become more pliable
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Heat the Ellman sheet over the bunsen flame until
it becomes clear
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Adapt the warmed sheet over the diagnostic cast
and quickly adapt it to the cast with Ellman Putty
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Ensure Ellman is very well adapted. It must
duplicate the Necessary detail yet be thick
enough not to flex during Fabrication of the
provisional
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Inspect surface detail
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Replace Ellman templates back onto original cast
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Mix some quick set plaster and put a small amount
on a plastic tile
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Wait for the plaster to develop some body and
then invert original cast with Ellman template
onto the plaster. You should not sink the cast
into the plaster, the aim of this is just to
capture the cusp tips of two teeth in front and
two teeth behind the preparations. Only index
that portion of your cast which is covered with
and Ellman if you do not plaster will stick to
your cast.
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Once plaster has set, remove from the cast and
trim index. Index should have enough thickness
that it should not break. Bucco-lingually it
should extend 4mm on either side of the teeth.
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Trim the acrylic template with sharp scissors to
include two teeth On either side of the prepared
teeth
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Fabricating a Single Unit Provisional
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Aiginate Impression of Preparations
Cut tip of monoject syringe with a Bard Parker
Blade , make opening big enough so that alginate
will flow out of it.
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Mix alginate, load syringe, inject around
preparation, load stock tray of appropriate size
and take an impression of preparation.
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Allow impression material to gel (wait one minute
until after the alginate is firm), and remove the
impression by snapping it out along the path
of insertion . Examine impression to insure teeth
and preparations have been accurately copied and
place impression in a damp towel
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Pour the impression as quick as possible with
quick set plaster. Alginate impressions distort
when not poured quickly
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Inspect the cast for its accuracy and detail.
Trim the cast on the model trimmer to include two
teeth on either side of the prepared teeth. Use a
bard parker blade or Hollenbackcarver to remove
and positive defects you may have.
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Do not trim plaster from the prepared teeth. This
will interfere with seating of the provisional.
If plaster cast has void on the surface of the
prepared teeth. The void should be filled with
white ivory wax to create a slight
over-contouring in that area.
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Try the template on the cast to ensure that it
fits accurately. If the template does not seat
completely trim the cast in areas which interfere.
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Remove a small amount of plaster from the contact
areas of the teeth adjacent to the prepared
tooth. This is done to compensate for the
polymerization shrinkage of the acrylic. Failure
to do this will result in an open contact area
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Apply alcote liberally to all surfaces of cast
with a soft camel hair brush. Remove the excess
with a gentle stream of compressed air.
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Mix appropriate shade of jet acrylic resin in a
dappen dish applying liquid To powder with a
spatula until a syrupy consistency is reached .
Pour the material into the template into the area
of the prepared teeth only. Wait until surface
of the resin looses its sheen and place template
onto cast. Ensure there are no air bubbles. If
there are, pierce the template with a sharp
explorer to allow air to escape. Fully seat the
template.
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Seat the original plaster index onto the Ellman
template. Ensure that the index seats onto the
cast accurately. Place elastic bands around it to
secure it. The purpose of the index is to ensure
that the Ellman template does not deform too
much so that discrepancies in occlusion are
minimized
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Place the cast into a pressure pot containing
water at 110 F. The water Should cover the cast.
Place the top on the pressure pot and bring
the Pressure to 20PSI. Process for approximately
5-6 minutes and remove cast from the pot
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With Ellman
Without Ellman
Remove the template and examine for any thin
spots or voids. If there Are defects add a small
amount of acrylic with a brush (salt and pepper)
and put the provisional back in the pressure pot.
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Remove provisional from the cast by breaking the
weak plaster with a plaster knife. Be careful not
to break the provisional. Remove any plaster That
remains on the internal with 1/2 Hollenback
carver . Examine internal for any nodules. Remove
nodules with a round bur
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Mark the margin with a sharp red/blue pencil
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Mark the contact areas with a pencil as you
contour the provisional In the interproximal
embrasures maintain the pencil mark which
Denotes the contact area
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Obtain DMX 3 bur, this will be used to trim and
contour the provisional restoration
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Begin trimming by breaking away the thin areas of
excess with your fingers. Use the DMX 3 bur to
start trimming the margins. Hold the bur in
harmony with the desired axial contours and
begin to thin the acrylic in the marginal areas.
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DO NOT hold the bur at an angle. If you do this
you will most likely trim your bevel away.
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Use the larger acrylic bur to refine the margin
area this bur does not leave a rough a surface
as the DMX 3
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View the provisional from the internal as you
trim to enable you to see the margins as the
acrylic is thinned. As you approach the margins
the acrylic will become paper thin. Use your
finger nail to break away thin areas of excess.
If you trim exactly to the margin you will
usually trim slightly sub.
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Fine Cuttle discs can also be used to thin and
smooth the acrylic in the marginal areas.
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Insert provisional onto tooth and evaluate margin
visually and with explorer. Gently slide explorer
across junction of preparation and provisional.
To obtain an R margins must be visually and/or
tactilely closed. The provisional should
extend exactly to the termination of the
preparation margin all the way around the
preparation
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Evaluate interproximal contacts mesially and
distally, mylar should pull through with some
resistance.
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When mylar drags you will see this thin line mark
on the strip of mylar. The criteria will be mylar
drag not clicking with floss.
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Evaluate thickness of provisional with calipers.
If you have prepared the tooth properly the
thickness of the occlusal portion of the
provisional should be between 1.3-1.5mm for
structural durability
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Prior to adjustment
After adjustment
Evaluate axial contours and emergence profile,
the emergence profile of the Provisional
restoration should be similar to the adjacent
teeth. Emergence profile should be flat as it
exits from the margin
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Evaluate marginal ridge height. The height should
be the same as the adjacent teeth. If they are
not they will require adjustment.
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Evaluate occlusion without provisional in place,
this will give you an indication as to which
teeth are contacting. These same teeth should
contact after you place the provisional
restoration.
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Check occlusion with provisional in place, check
to see if the same contacts hold as when the
provisional was not in place.
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Use Accufilm articulating paper and mark contacts
without the provisional And with the provisional
in place
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Using an acrylic bur adjust the contacts until
the adjacent teeth come into contact. The
criteria for occlusion is that the provisional
should hold mylar. The adjacent teeth should be
in the same occlusal relationship as they
were prior to the provisional being placed
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Keep marking contacts and adjusting
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The provisional restoration should hold mylar and
the adjacent teeth should Be in the same occlusal
relationship as they were prior to the
provisional being inserted HYPO or HYPER
occlusion will grade a T
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Carve in occlusal anatomy with an inverted cone
or 702 bur in a slow speed. Ensure that you do
not remove the occlusal contacts that were
previously established.
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Occlusal Anatomy
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Acrylic dust and debris can be removed with a
soft Robinsons brush
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Polish with wet flour of pumice and a bristle
brush on a lathe first. ALWAYS POLISH AWAY FROM
THE MARGIN. To obtain a high shine polish using a
dry rag wheel and white diamond compound.
Difficult to reach areas can be polished using
flour of pumice and a Robinsons brush and white
diamond compound and a Robinsons brush . Clean
the provisional using soap and water on a soft
brush
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Try in the finished restoration
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Evaluate Marginal Integrity
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Evaluate interproximal contacts
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Evaluate axial contours and marginal ridge height
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Evaluate internal and occlusal thickness of
provisional
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Evaluate overall shape of provisonal
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Evaluate occlusion and surface finish
GRADE YOUR PROVISIONAL AND THEN TAKE IT TO
THE TWO FACULTY ASSIGNED TO YOUR GROUP FOR GRADING