Working Casts & Dies

Working Casts & Dies

Classification of the working cast and die

systemsI-Working cast with separate die.

II-Working cast with removable die:

A. DowelPinTechnique.

B. DI-LOCK Tray Technique.

C. Pindex System.

D. DVA system. E. Zeiser system.

III-Single Die Technique:

Stone die - Amalgam die - Acrylic die - Refractory die (Ceramic

die) - Flexible die - Electroplated die: Silver plated or Copper

plated.

A. Dowel Pin Technique


Dowel Pin



Dowel Pin poppy pin


Poppy Pin

Straight Pin

Dowel Pin

Paper clip


A ball of soft wax is placed on the dowel pin tip and

application of separating medium.


The base of the cast is poured and removed from the

impression.


Wax at the end of the dowel pins is located and removed.


Die is separated from the cast with a fine saw.


Sectioning should be slightly tapered towards the base of

the model.


-Die trimming.

-Marking the finish line.

-Application of die spacer.




A. Dowel Pin Technique.


C. Pindex System.





plated.

B. Die-lock tray

-It is a snap apart plastic tray which has an

internal orienting grooves and notches that

help to assemble the working cast and die.

B. Die-lock tray

-Technique

The cast should be a U-shape with no stone in the centre

B. Die-lock tray

-Technique

Horizontal grooves are cut in the cast base to give it

a retention.

B. Die-lock tray

-Technique

● The tray is filled with a new mix of dental stone.

● The U-shaped cast is seated in the tray on the stone mix.

● The cervical line of the teeth should be 4 mm above the tray

edge.

B. Die-lock tray

-Technique

After stone hardening, the tray is dis-assembled and the cast is

removed from the tray.

B. Die-lock tray

-Technique

● A saw cut is made on each side of the prepared tooth.

● The die is separated from the cast by finger pressure.

B. Die-lock tray

-Technique

-Die trimming.

-Marking the finish line.

-Application of die spacer.

B. Die-lock tray

-Technique

- The die and other parts of the casts are reassembled

in the tray.

B. Die-lock tray

-Technique

- Mounting the die-lock tray on the articulator.




A. Dowel Pin Technique.


C. Pindex System.





plated.

using

working cast with removable die

Pindex system

C. Pindex system

It is similar to a dowel pin system but create a working cast

with dies with great precision.

● impression taking:

The impression is cleaned and placed in a disinfectant

solution.

● Mixing stone:

A correct stone powder/water ratio is mixed in a

mixing bowel using a vacuum mixing unit.

● Pouring The impression:

The impression is held on the vibrator and poured

with a proper mix of stone from one side using a

spatula.

● The impression is completely poured with dental

stone.

● The working cast is trimmed at its periphery and

at its base to the correct height.

● A minimum height of 10 mm at edentulous ridge

area is essential to avoid fracture of the cast.

● The cast is trimmed from the lingual aspect by

arbour band.

● The central position of the pinhole required for

dowel pin is marked.

● All crowns, bridge units and adjacent teeth should

be pinned.

● The rest of the dental arch should also be

supported by at least two dowel pins.

● The planned saw cuts of the model segments are

marked with a pencil.

Pindex machine

● The cast is placed on the pindex machine and the

pilot light is used as a guide to drill holes in the base

of the cast.

● The platform of the pindex machine is spring

loaded. When the cast is pressed against the

platform, the motor will get activated to drill a hole in

the base of the cast.

● The drilled pinholes in the base of the cast.

● The fit of each dowel pin into the pinhole is

checked.

● Each dowel pin is glued and inserted into pinhole

using a pin holder.

● A base stone with a different colour is mixed in a

vacuum mixing unit.

● After applying a separating medium at the base of

the cast, the pins are coated with the stone on the

vibrator.

● A base former is poured with the same stone to

form a stone base.

● The cast with the fixed dowel pins is lowered onto

the stone base.

● After setting of the stone base, the rubber base

former is removed. Saw cuts follow the marked

segments of the cast using a hand saw.

● The die is separated from the cast and cleaned

from the stone dust.

● The preparation margin is carefully trimmed,

smoothed and cleaned.

● Each die is checked for easy removal from the base

without interference.

● Die sealer and die spacer are applied to each die.

CAD/CAM

Computer Aided Design (CAD)

CAD is the process of using

software to assist in precision

drawing and designing models to

aid in their manufacturing.Computer Aided

Manufacturing (CAM)CAM is the process of using

software to analyze and

manufacture models.

◼ Cad Camis a subtractive process

+Scanner

3D scanner

softwareComputer

Designing

software

Milling

machine

◼ Digitizing (scanners)

◼ Designing (software)

◼ Milling

CAD CAM

Digitizing

Designing

Milling

Digitizing : is the use of a 3D measurement

system to capture features ( gather data ) of

a n o b j e c t .

Digital Modeling : is the process of creating

a computer model of an object that exactly

repl icates the form of that object .

Digitizing

Digitizing

Intraoral optical impression

using 3D camera.

Fast

Rapid

production of a prototype (trial product ,model or sample (

typingproto type

What is RP ?

An additive manufacturing

process that creates an object

directly from a CAD model by

building it in layers

3D scanner Computer

CAD softwareSTL software3D printer

Selective Laser Sintering (SLS)

◼ It uses laser to draw cross-sections in a bed of fine,

heat-fusible powder. The laser raises the temperature of

the powder particles momentarily to where they sinter

(“Sintering,” means welding without melting.).

◼ SLS works with a broad range of materials powder,

including thermoplastics, metal powder, casting wax

and ceramic powder.

Laser source

Powder feeder 1 Powder feeder 2Work platform

SLS-2500

Fused Deposition Modeling (FDM)

◼ FDM acts like a finely controlled hot-melt glue

gun. But instead of glue, FDM gingerly extrudes

an ultra thin layer of thermoplastic filament.

◼ Actually, two filaments are extruded: one for the

model and the other for the undercut/overhang

support.

◼ No laser is involved.

Liquifier head ( moves in X and Y )

Stratasys

Three-Dimensional Printing (3DP)

◼ Imagine an ink-jet printer. Now think of it producing

3D prototypes instead of printed pages. That’s the 3DP

technology.

◼ No laser is involved.

3-D Printing

Wax pro

150 wax copings per 8 hours

Neo

200 wax or resin copings per day

Bench-top 3D printers

Solidscape

Thank you

Documents

Working Casts & Dies