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Denture+Base+Repairs

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									DENTURE
BASE
REPAIRS
    Midline fracture of the
       maxillary denture

most common fracture.
  ridges resorb and remodel.
  palatal bone does not resorb.
     “high-centering” of the
     denture.
       rocking effect accelerates
       bone loss.
       leads to a stress fracture.
#1 rule when repairing fractures
of a complete or partial denture

Always fit the pieces of the denture
together with sticky wax and place it
against the opposing denture or a cast
of the opposing teeth to ensure that
the denture is correct for the patient.
Some patients have been known to
supply someone else’s denture.
Repairing a Fractured Complete
            Denture
    When a midline fracture of a maxillary complete
denture occurs, the cause must be determined. As
with any fracture, this must be corrected if the
repair is to be successful. First, assemble the
pieces and try them against a cast of the opposing
dentition.
1. Align the parts of the fractured denture and
splint them into position using long shank dental
burs, coat hanger wires, plastic sticks, or large
paper clips. “Tack” these to the teeth with
sticky wax. Avoid wooden sticks as these can
absorb water and warp.
2. Block out all undesirable undercuts that are
more than 10mm from the fracture site with
wet tissue paper, putty, or wet pumice. Leave
about 2mm of the denture flange borders
uncovered and pour a base of quick-set plaster
or stone.
3. After the stone has set, remove the bracing
rods and sticky wax. Remove the denture
pieces from the stone matrix, clean them and
the matrix, reassemble them to ensure that
they can be accurately positioned.
4. Bevel the approximating surfaces so that there
is a 3mm gap on the outside and a 2mm gap on the
cast side. This will allow you to see that the
acrylic is filling the entire area. Replace the
pieces in position on the cast and check for
accuracy.
5. “Rabbet” the polished side of the
approximating pieces about 3mm wide and half way
through so that there is a gap totaling about 8mm
in the surface area between the pieces. Leave out
any small pieces, and replace them entirely with
repair acrylic.
6. Paint separating medium on the cast at least
10 mm to either side of the fracture line. “Tack”
the parts in position to the cast base with sticky
wax. Use the “brush-bead” method to overfill
the repair area with repair acrylic. Place the
entire assembly in warm water in a pressure pot
and allow it to cure.
7. After the acrylic has set for ten minutes,
remove the denture repair from the stone
matrix and finish the denture with successively
finer abrasives until a high shine is achieved.
Check the tissue side for irregularities and
repair and/or smooth them.
8. Inspection of the denture
shows a smooth line at the
junction of the denture base
acrylic and the repair acrylic.
Note the repair acrylic has
permeated the crack in the
denture tooth. This tooth can
now be replaced in a subsequent
procedure.
 The following pictures will demonstrate how you will
  successfully repair a fracture of a mandibular
  compete denture. This is the procedure you will
  complete in the lab exercise. Red DuralayR resin will
  be used so that the juncture can be easily seen. If
  this were done on a patient’s denture, a repair
  acrylic matching the denture’s original acrylic would
  be chosen.
 First approximate the
  broken pieces and fix
  them in position with a
  non-absorbing splinting
  material (Wire,
  plastic,etc.)
 Use sticky wax to lute
  these braces to the
  denture base.
 Check the tissue surface
  to make sure that the
  pieces are in close
  contact and there is no
  wax or other debris on
  that surface.
 Use polyvinylsiloxane putty (Reprosil®) to block out the
  area away from the fracture site.
 Leave about 10 mm. of the surface on the tissue side
  bare of any putty.
 Press pieces of paper clip into the putty before it sets
  to provide retention of the putty to the plaster base of
  the repair cast.
 Pour a mounting plaster base to complete the repair
  cast.
 Remove the splinting material and all
  the sticky wax from the denture
  surface and the repair cast.
 Remove the denture pieces from the
  cast and inspect the area under the
  fracture site for any defects.
 Replace the denture pieces on the cast
  and examine them to ensure that they
  fit precisely back into place.
 Remove approximately 1.5 mm. acrylic from the proximal
  surfaces of the fracture line on the polished surface and
  1 mm on the tissue side, forming a gap of 2 mm. on the
  tissue surface and 3 mm. on the polished surface.
 Place the pieces back on the cast and verify these
  dimensions. It is necessary that this amount of gap be
  present to allow enough visual and working access so the
  repair acrylic can be placed and fill the entire repair site.
 Remove enough acrylic from the
  polished surface side of the
  denture to allow a gap of 8-10
  mm. This process is called
  “rabbeting”and provides an
  increased surface area that
  affords a stronger joint between
  the old and new acrylic.

       BEVEL




      CAST

      RABBET




      CAST
 Paint the area under the site to be repaired with
  ALCOTE, a tin-foil substitute.
 Replace the denture parts and lute them in place
  with sticky wax. Note the amount of visual and
  working access provided by the rabbeting and
  beveling.
 The method to be used to
  apply repair acrylic to the
  denture in this exercise is
  called the “brush-bead”
  method.
 Dappen dishes containing
  monomer and polymer are
  arranged close to the denture.
 The brush is first “wetted” in
  the liquid monomer.
 Then it is dipped in the
  polymer powder.
 This will cause a small bead to
  form on the wetted end of the
  brush.
 These beads are placed in the
  repair site to make the repair.
 Wet the fragment edges
  with monomer.
 Moisten brush in monomer
  and dip it in polymer.
 Brush bead the wet
  polymer on the repair site.
 Add additional acrylic until
  the entire site is slightly
  over-filled.
 Place the repair cast and denture in a water bath
  to cure. Dip the brush in monomer and dry it
  thoroughly on a paper towel to remove any residual
  acrylic to prevent ruining the brush. If this step
  is forgotten, the acrylic will harden and the brush
  will be ruined.
 Extra acrylic is added to
  overbuild the repair site
  area to assure that there is
  sufficient thickness of high
  quality acrylic. Moisture
  from the water bath can
  cause a rough surface to
  form.
 Remove the repaired denture
  from the repair cast and
  verify that the tissue side
  has been repaired.
 Remove the denture from the cast
  and check to make sure that the
  acrylic is of good quality and
  covering all the desired areas.
 Place the dentures together and ensure that they occlude
  properly. If the occlusion is off, then the repair is not
  accurate. This is a very good reason to make sure you
  fit the dentures together before making the repair cast.
  The patient may be giving you a mismatched set.
 After ensuring that the
  dentures fit together
  properly, remove the excess
  acrylic with a denture bur
  and use abrasives and
  polishing agents to polish
  the repaired area, taking
  care to not over-polish the
  area or the teeth. Also be
  sure to change the polishing
  wheel for each abrasive.
 Can you tell where this
  denture has been repaired?
  You have to look closely to
  discern the repair site
  because the repair acrylic
  blends together so precisely
  with the original acrylic. This
  is how a repair should look!
   A reline of the denture will likely
be necessary to correct the conditions
that led to the fracture in the first
place. Often what the patient really
needs is a new denture. If the patient
balks at these suggestions, have them
sign the record stating that they
understand the potential for future
fractures and are willing to take the
risk and assume the responsibility.
This fracture is not completely across the
entire denture.
Cover the break with sticky wax. If there is
a gap between the teeth, then squeeze them
back together and splint them.
Pour a modified working cast after blocking out
non-essential areas. Since the pieces are
together, polyvinylsiloxane putty can be used to
make this repair cast.
Clean off all the sticky wax and open the
crack with a fissure bur to 2 mm.
On the polished side, use a round-nosed acrylic
bur to reduce the acrylic and increase the
surface area to be bonded.
  Overfill the fracture site with autopolymerizing
resin. This will assure that a high quality of acrylic
will be left after finishing. The acrylic that
contacts the water will be porous and look “grainy”.
Cut back the excess acrylic, finish, and polish the
repaired denture. Correct any irregularities found
on the tissue surface.
Repairing a Complete
 Denture that has
  Multiple Breaks
                         A




A. Assemble the broken pieces of the denture to
determine if the denture can be repaired
successfully. If there is any part missing, sticky
wax the denture back together and place it in the
mouth. Make an alginate impression of the denture
in the mouth and pour it up with the denture left in
the impression, and pour it with a fast-set plaster.
                        B



B. If all the parts are available and will fit back
together with a reasonable assurance of accuracy,
fix them together with sticky wax. Splint them with
metal or plastic sticks & block out any nonessential
undercuts. Pour a cast in quick set plaster or stone.
                     C
C. Rabbit and bevel the breaks as usual, but
leave out the broken piece. Paint the cast
with tinfoil substitute and reposition only the
large pieces back on the cast.

								
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