1. Assalamu-alaikum
DR. TAJAMMUL AHMED

2. Fabrication of working casts and dies.

3. 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.

4. 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

5. TYPES OF DIE MATERIALS Gypsum: Type IV-dental stone, high strength
Type V-dental stone ,high strength, high expansion
Dental stone + lignosulphonates
Metals:
Electroformed/eletroplated.
Sprayed metals.
Amalgam.
Polymers;
Metal-filled resins or inorganic filled resins.
Epoxy.
Cements:
silicophosphate or
polyacrylic acid bonded cements.
Ceramic or refractory die materials:
For direct baking of porcelain crown or preparation of wax pattern for casting.
Type IV& Type V Stone dies, Electroformed dies, Epoxy resins , Refractory materials are recommended die materials.

6. 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.

7. 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

8. TYPES OF DIE SYSTEM
Based on the design, die systems can be classified into:
2. Working cast with separate die system
1. working cast with removable die system three commonly used removable die systems,
a)Dowel pin system
-Straight
-Curved
b)Di-lok tray system
c)Pindex system

9. 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
Systems using pre formed plastic trays without die pins
straight
curved

10. Attached to the underside of the cast that has already been poured
a. DOWEL PIN SYSTEMS
They are prepared using two techniques, namely
Pre pour technique
Post pour technique
Devices are oriented
in the impression
before it is poured
Attached to the underside of the cast that has already been poured

11. 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.

12. 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.

13. 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.

14. 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.

15. Base of cast togingival crest
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

16. 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.

17. Dies are sectioned from underside and from occlusal aspect
Working cast with removable die mounted on an articulator

18. 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.

19. 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

20. Working cast with separate die
Advantages:
Easy to fabricate
Keeps relation between abutments fixed
better contours and emergence profile while wax pattern fabrication.
Disadvantages
Wax pattern must be transferred from die to cast
destroy internal adaptation of wax
Some times difficult to seat wax pattern on the cast
Different impressions
Second pour
–impression damaged
Different thickness of spacers

21. 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.

22. THANK YOU