Assalamu-alaikum
DR. TAJAMMUL AHMED
a.tajammul@gmail.com
SPECIFIC LEARNING OBJECTIVES;
At the end of the class student should be able;
To define a die
Type of die materials
To enumerate the classification of die materials & die systems.
To enumerate the steps involved in preparing working cast &
dies.
Definition
DIE:
Die is a positive replica of the individual pre-pared tooth on which the
inlays, crowns, bridges are made.
These are individual tooth replicas prepared for;
1. easier handling during wax pattern fabrication and
2. finishing of inaccessible areas of the cast
TYPES OF DIE MATERIALS
Type IV-dental stone, high strength
Gypsum:
Type V-dental stone ,high strength, high
expansion
Dental stone + lignosulphonates
Electroformed/eletroplated.
Metals:
Sprayed metals.
Amalgam.
Metal-filled resins or inorganic filled resins.
Polymers;
Epoxy.
Cements:
Ceramic or refractory die materials:
silicophosphate or
polyacrylic acid bonded cements.
For direct baking of porcelain crown or
preparation of wax pattern for casting.
IDEAL PROPERTIES OF DIE MATERIALS
It should be dimensionally accurate.
It should have high abrasion resistance, should possess good strength,& have
smooth surface .
Toughness – to allow burnishing of foil & resist breakage.
Ability to reproduce all fine details in the impression.
Compatibility with all impression materials.
Colour contrast with wax, porcelain & alloys.
Easy & quick manipulation & rapid fabrication.
Non-injurious to health by touch or inhalation.
Economic.
IDEAL REQUIREMENTS OF A DIE SYSTEM
The die should be easy to remove and replace in its original
position.
The die must be stable when placed in the cast.
It should be easy to mount on the articulator
TYPES OF DIE SYSTEM
Based on the design, die systems can be classified into:
a)Dowel pin
system
1. working cast with removable die system
three commonly used removable die systems,
b)Di-lok tray
system
c)Pindex system
2. Working cast with separate die system
-Straight
-Curved
WORKING CAST WITH A REMOVABLE DIE SYSTEM
In this system a special type of working cast is prepared and
the dies are carefully sectioned so that the individual dies can
be removed and replaced in their original position in the cast.
Methods of repositioning die in its working cast
systems using die pins
dowel pin systems
straight
curved
Systems using pre formed
plastic trays without die pins
a. DOWEL PIN SYSTEMS
• They are prepared using two techniques, namely
Pre pour technique
Devices are oriented
in the impression
before it is poured
Post pour technique
Attached to the underside of
the cast that has already
been poured
PRE-POUR TECHNIQUE
The dowel pin is positioned within the impression
using sticky wax
First pour is poured upto the level of the alveolar
process
Separating medium is applied and the base is poured
After the cast is set, the dies are sectioned by placing
vertical sections in the interproximal regions using a
die sectioner.
Since the separating medium was applied before
pouring the second half of the cast, the dies can be
easily separated with vertical sections alone.
POST-POUR TECHNIQUE
Here, the cast is poured up to the level of the crowns of the teeth in
the impression.
Subsequently, small holes are drilled within the first pour in the
required places and the dowel pins are cemented into the holes
The remaining part of the cast is poured and the dies are sectioned as
described in the pre-pour technique.
b. DI-LOK TRAY SYSTEMS
In this technique to pour the cast, use special tray with
orientation grooves on the inner aspect & is made of
multiple components, which can be assembled or
dismantled.
Impression is poured using two-pour technique.
The first pour is poured up to the level of the impression
and the second or base pour is poured after positioning
the rim of the di-lok tray over the impression.
Later, the di-lok tray is dismantled and the grooves on
the base of the cast formed by the di-lok tray is used as
a guide to do die sectioning.
c. PINDEX SYSTEMS
This system is similar to the post-pour
dowel pin technique.
Special drill press equipment is used to
do die sectioning.
The drill press has a platform with a slot
like opening through which the drill pin
will project during the procedure.
Die sectioning procedure is simple wherein the cast of 15 mm base is placed on
the drill press and drill holes are prepared in the under surface of the base of
the cast using the pilot light as a guide.
The unit has a red pilot light lamp on top, which will shoot a point exactly on
the drill & act as a guide while drilling
Base of cast togingival crest
15-20 mm
After making the drill holes to the required depth, sleeved die pins are
placed and cemented using cyanoacrylate adhesive.
After cementing the pins, a base is poured over the base of drilled cast.
Dies are sectioned from underside and from occlusal aspect
Working cast with removable die mounted on an articulator
WORKING CAST & SEPARATE DIE SYSTEM
Here, two casts are poured from a single
impression.
One cast is sectioned and used as a die and
The other is not sectioned and is used as the
working cast.
The wax pattern is prepared on the die and later
transferred to the working cast.
The die is shaped and finished using an acrylic
trimmer and the portion of the die below the
cervical line is finished using a scalpel.
Sharp undercuts in the base should be avoided.
Working cast with separate die
Procedure
Both working cast and sectional die can be obtained
by:
• Pouring impression twice or
• Making two impressions.
Stone added to side of prepared teeth in impression in
small increments. Tray tilted to fill the Impression
displacing air as it moves
Build the height of cast to approx 1 inch.
Trim sectional cast to obtain die.
Die contour be approximately like root to facilitate
good axial contours in restoration
Working cast with separate die
Easy to fabricate
Advantages:
Keeps relation between abutments fixed
better contours and emergence profile while wax pattern
fabrication.
Wax pattern must be
transferred from die to cast
Disadvantages
destroy internal
adaptation of wax
Different impressions
Some times difficult to seat
wax pattern on the cast
Second pour
–impression damaged
Different thickness of
spacers
CONCLUSION
A good impression and accurate die are the first
steps towards the fabrication of an accurate
restoration.
Proper selection of the die material and its
manipulation are paramount to achieve accuracy in
the die.