3. WORKING CAST
is the cast that is
mounted on an
articulator. To provide
the most accurate
articulation, it
normally should
represent the entire
arch
4. REQUIREMENTS FOR GOODREQUIREMENTS FOR GOOD
CASTSCASTS
1. bubble free1. bubble free
especially along the finish lines of theespecially along the finish lines of the
prepared teeth.prepared teeth.
2. distortion free.2. distortion free.
3. trimmed3. trimmed
to insure access for carving wax patternto insure access for carving wax pattern
margins.margins.
6. WORKING CAST WITH A SEPARATE
DIE
disadvantages
wax pattern must be transferred from one to the
other
internal adaptation
obtained from
separate impressions
pouring an elastomeric full-arch impression twice
first cast is used for fabrication of the die
18. IF A REMOVABLE DIE SYSTEM IS
USED, IT SHOULD SATISFY THESE
REQUIREMENTS17
The dies must return to their exact original
positions.
2. The dies must remain stable, even when
inverted.
3. The cast containing the dies must be easy to
mount on an articulator
19. WORKING CAST WITH A
REMOVABLE DIE
Most of these devices
can either be oriented
in the impression
before it is poured
attached to the
underside of a cast
that has already been
poured
prepour technique post-pour technique
20. WORKING CAST WITH A
REMOVABLE DIE
1. Straight dowel pin
2. Curved dowel pin
3. Pindex system
4. Di-Lok tray
5. Accutrac
30. curved dowel (A),
positioning bar (B),
straight pins (C)
first pour of die stone
(D) to the impression
Depressions are made
about 2.0 mm deep on
either side of the
dowels in the two large
segments of the cast
that will carry the
unprepared teeth
CURVED DOWEL PIN
31. coat of petrolatum is
applied to stone & dowels
Boxing wax with the tips
of the dowels sticking
CURVED DOWEL PIN
32. CURVED DOWEL PIN
The completed cast is
sawed
Segment is removed by
pressing on the exposed tip
34. CEMENTED CURVED PIN
The working cast is trimmed
to receive cemented dowels
Holes are drilled into the underside of
the cast, under the indicated locations
42. PINDEX SYSTEM
Pencil marks are placed
under illuminated dot
The thumbs are used to
stabilize the cast while
lifting the handle bar
with the fingers.
43. PINDEX SYSTEM
Debris is removedDebris is removed pin holes refinedpin holes refined
Shorter pins 1stShorter pins 1st Cyanoacrylate cementCyanoacrylate cement
44. PINDEX SYSTEM
White sleeves > long pinsWhite sleeves > long pins bottom of cast is lubricatedbottom of cast is lubricated
Utility wax > long pins.Utility wax > long pins. gray sleeves are blockedgray sleeves are blocked
45. PINDEX SYSTEM
A palatal/tongue fillerA palatal/tongue filler The filler is placed on theThe filler is placed on the
castcast
Boxing waxBoxing wax The filler is seated to theThe filler is seated to the
castcast
46. PINDEX SYSTEM
Microstone is pouredMicrostone is poured The base former filledThe base former filled
Model seated to base formerModel seated to base former Stone is vibrated on bottomStone is vibrated on bottom
47. PINDEX SYSTEM
Wax over the long pins isWax over the long pins is
removed.removed.
The sawThe saw cuts are premarkedcuts are premarked
Dies are sectioned from theDies are sectioned from the
undersideunderside
The cast is removed by tappingThe cast is removed by tapping
the pinsthe pins
48. PINDEX SYSTEM
Dies may also sectioned from
the occlusal
A large condenser also be
used to loosen
cast should be poured in a U
shape, no stone in the center.
The completed cast on the
articulator
49. PINDEX SYSTEM
The lingual side of the cast base
is trimmed with an arbor band.
Horizontal grooves are cut in
the base to give it retention
51. DI-LOK TRAY
The cast is placed into stone
in the tray
Disassembly of the cast.
A saw cut is made on each
side of the prepared tooth
The cast is loosed by tapping
on the front of the base
52. DI-LOK TRAY
The prepared tooth is broken
free from the cast
die is trimmed
The cast and tray mounted on
the articulator
The cast and die(s) are
reassembled in the tray