Post on 28-Jan-2015
description
WORKING CAST
is the cast that is mounted on an articulator. To provide the most accurate articulation, it normally should represent the entire arch
REQUIREMENTS FOR GOOD CASTSREQUIREMENTS FOR GOOD CASTS
1. bubble free1. bubble freeespecially along the finish lines of the especially 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 pattern to insure access for carving wax pattern margins.margins.
WORKING CAST WITH A SEPARATE DIE
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
IMPRESSION POURING
DIE PREPARATION
Stone is added Tray is tilted
DIE PREPARATION
Stone is added to the impression
The die is first trimmed on a model trimmer
DIE PREPARATION
handle is slightly larger than preparation. Improperly trimmed die
DIE PREPARATION
The handle should be 1 inch long
The die is trimmed with an acrylic bur.
DIE PREPARATION
Shaping near the finish line with a scalpel
The die is with the discoid end of a Tanner carver
ERROR !!!This die is too short, and it does not allow adequate access for margin finishing.
DIE CONTOURS SHOULD BE SIMILAR TO THOSE OF A NATURAL TOOTH
DIE PREPARATIONAxial contours of the wax pattern are influenced by die trimming.
finish line on die outlined with a redred pencil.
DIE PREPARATION
Die relief agent One-piece die
WORKING CAST WITH A REMOVABLE DIE
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
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
WORKING CAST WITH A REMOVABLE DIE
1. Straight dowel pin 2. Curved dowel pin 3. Pindex system 4. Di-Lok tray 5. Accutrac
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A, flat-sided single dowel;
B, single curved dowel;
C, double straight dowels with a common head;
D, two separate parallel dowels;
E, keyed plastic outer tray
STRAIGHT DOWEL PIN
Dowel pins positioned over the impression
Paper clips are added to nonremovable parts
The stone around the dowel pins is lubricated
paper towel used to fill in the open, center portion
Wax at the ends of the dowel pins is removed
Dies are separated from the rest of the cast
the ends of the dowel pins are tapped to loosen
Base of die is trimmed with an acrylic bur.
Dies are reseated into the cast
wax is removed from the ends of the dowel pins.
PART 2
ANY QUESTION ?
CURVED DOWEL PIN
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
coat of petrolatum is applied to stone & dowels
Boxing wax with the tips of the dowels sticking
CURVED DOWEL PIN
CURVED DOWEL PIN
The completed cast is sawed
Segment is removed by pressing on the exposed tip
CEMENTED CURVED PIN
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
CEMENTED CURVED PIN
The cast is keyed with a large acrylic bur cyanoacrylate cement
CEMENTED CURVED PIN
The head of a curved dowel is seated
saw cuts after the base is poured
PINDEX SYSTEM
PARTS OF THE PINDEX MACHINE.
PINDEX SYSTEM
sufficient stone to allow for trimming is added
The bottom of the cast is trimmed
PINDEX SYSTEM
The cast should be 15 mm thick
The periphery of the cast is trimmed
PINDEX SYSTEM
The palate/tongue area is trimmed
Location of the pin holes is marked with a pencil
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.
PINDEX SYSTEM
Debris is removed Debris is removed pin holes refined pin holes refined
Shorter pins 1stShorter pins 1st Cyanoacrylate cementCyanoacrylate cement
PINDEX SYSTEM
White sleeves > long White sleeves > long pins pins
bottom of cast is bottom of cast is lubricated lubricated
Utility wax > long pins.Utility wax > long pins. gray sleeves are blocked gray sleeves are blocked
PINDEX SYSTEM
A palatal/tongue fillerA palatal/tongue filler The filler is placed on the The filler is placed on the castcast
Boxing waxBoxing wax The filler is seated to the The filler is seated to the castcast
PINDEX SYSTEM
Microstone is pouredMicrostone is poured The base former filledThe base former filled
Model seated to base Model seated to base former former
Stone is vibrated on Stone is vibrated on bottom bottom
PINDEX SYSTEM
Wax over the long pins is Wax over the long pins is removed.removed.
The saw The saw cuts are cuts are premarkedpremarked
Dies are sectioned from the Dies are sectioned from the undersideunderside
The cast is removed by The cast is removed by tapping the pinstapping the pins
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
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
DI-LOK TRAY
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
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
مارژین که صورتی مارژین در که صورتی دربه خورده تراش به دندان خورده تراش دندانباشد نزدیک مجاور باشد دندان نزدیک مجاور دندانترجیح دای تکنیک ترجیح کدام دای تکنیک کدام
؟ ؟ دارد دارد