Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.

1. DIE AND DIE MATERIALS
GYPSUM PRODUCTS :
Gypsum (CaSo4 2 H2O) is a mineral mined in various parts of the
world however it is also produced as a byproduct of some chemical
processing operations.
Chemically the gypsum produced for ductal applications in nearly
pure calcium sulfate dehydrate.
Production of Calcium Sulfate Hemihydrate :
Plaster and stone are produced by cabining calcium sulfate dehydrate
or gypsum.
The gypsum in ground and subjected to temperatures of 1100
to 1200
C to drive off the water of crystallization and this is the amount of water
needed to convert calcium sulfate dehydrate to calcium sulfate hemihydrate.
CaSo4 2H2O CaSo4 ½ H2O CaSo4 CaSo4
Depending on the method of calcination, different forms of
hemihydrate can be obtained. They are α, β and α-modified hemihydrates.
α - hemihydrate is called artificial stone, die stone (or) improved
stone, ti consists of smaller, regularly shaped crystalline particles in the
form of rods / prisms. (fig. 10-2 pg. 258 phillyes).
Irregularly shaped orthorhombic crystals particles with capillary
pores.
(Fig: 10.1 pg. 256 philly)
α - modified hemihydrate is made by boiling the gypsum in a 30%
aqueous solution of calcium chloride and magnesium chloride. This process
yields the smoothest, most dense powder particles.
1300
C –
2000
C
1100
C –
1300
C
1300
C –
2000
C
2000
C –
10000
C
Hexagonal
anhydrite
Orthorhombic
anhydrite

2. Types of Gypsum products :
The various types of gypsum products identified by ADA are :
1) Plaster, impression
2) Plaster model
3) Dental stone
4) Dental stone high strength
5) Dental stone high strength and high expansion.
Properties of Gypsum products :

3. Type W/p ratio
Setting
tim
es
(mi
nt)
Setting expansion
after 2 hr.
Compressive
strength
after 1 hr.
Mini Maxi Mpa Psi
1) Plaster
impress
ion
0.40-0.75 4 ± 1 0.00 0.15 4.0 580
2) Plaster
model
0.45-0.50 12 ± 4 0.00 0.30 9.0 1300
3) Dental
stone
0.28-0.30 12 ± 4 0.00 0.20 20.7 3000
4) Dental
stone
high
strengt
h
0.22-0.24 12 ± 4 0.00 0.10 34.5 5000
5) Dental
stone
high
strengt
h high
expansi
on
0.18-0.22 12 ± 4 0.10 0.30 48.3 7000
In type III the compressive strength is 20.7 Mpa but it does not
exceed 34.5 Mpa. This is used for the construction of the casts in the
fabrication of full dentures that fit soft tissues.
Stone dies are reproductions of prepared teeth, on or within which
prostheses are constructed. Because of the severe wear conditions that occur
at the margins during carving of the wax patterns and because of higher

4. stresses induced in stone dies try-in and adjustments, greater strength and
hardness are required of the die materials.
Dental stone, high strength (Type IV) :
The principal requisites for a die material stone are :
• Strength
• Hardness
• Abrasion resistance
• Minimum setting expansion.
↓
So α-hemihydrate of densite type is used.
• It consists of cuboidal – shaped particles.
↓
The reduced surface area due to the shape of the particles produce above
properties without under thickening of the mix.
• It gives hard surface as the surface dries more rapidly.
• It is resistant to abrasion.
o They are necessary because cavity is filled with wax that in
carved flush with the margins of the die.
o As sharp instruments are used for caring stone must be resistant
to abrasion.
• The surface hardness of –
Type IV – 92 Rock well hardness
Where as Type III – 982 Rock well hardness.
Even though the surface of Type IV in hard care should be
observed when the pattern is being carved.
Dental stone, high strength, high expansion (Type IV) :

5. • This type V has compressive strength (48.3 Mpa) higher than that of
Type IV (34.5 Mpa).
↓
• This is due to making it possible to lower w/p ratio than Type IV.
• The setting expansion has increased from 0.10% (Type IV) to 0.30
(Type V).
↓
The rationale for the increase in setting expansion is that base metals
have greater casting shrinkage than do the traditional noble metal alloys.
↓
Thus higher expansion is required in the stone used for the die to aid
in the compensating for the alloy solidification shrinkage.
• Indicated in the cast crowns (when inadequate expansion have been
achieved during the fabrication).
• It is not indicated in the production of dies for inlays, since the higher
expansion may lead to unacceptably tight fits.
Propositioning :
• The strength of the stone is inversely proportional to the water
powder ratio.
Strength α
↓
So amount of water should be as low as possible.
↓
It should not be so low that the mix will not flow into every detail of
the impression.
1
W/P

6. • The water volume should be measured by using accurate graduated
cylinder.
• The powder should be proportioned by weighing balance.
↓
• Powder should not be measured according to volume became powder
varies from product to product and does not pack uniformly.
W/p raio
Type IV : 0.22 – 0.24
Type V : 0.18 – 0.22
MIXING :
1) Hand mixing :
• It is accomplished in a flexible rubber or plastic bowl by using
a stiff bladed spatula.
• The walls of the bowl should be smooth and resistant to
abrasion.
• Incorporation of air during mixing is avoided.
↓
Air bubbles are unslightly, weaken the material and produce
surface in accuracies.
• The water should be placed in the mixing bowl and the powder
should be shifted into the water.
↓
When powder sinks into the water without an agglomeration of the
particles, les air is carried down.
• The mixing is completed when all the mixture is smooth and
homogeneous in nature.

7. • The further mixing is likely to breakup the crystals of the
gypsum formed and thus weaken the final product.
• The time for hand mixing is approximately 1 to 2 month.
• Addition of more powder to a mix that is judged to be too thin
provides essentially 2 mixes of stone.
↓
It will set at different times
↓
Results in weakened product.
• Addition of water to a too thick mixture causes
↓
Disarrangement of crystalline growth and a lack of intercrystalline
cohesion.
Mechanical Mixing :
• The use of mechanical spatulator to mix gypsum products
offers considerable advantage.
• Rapidly moving blades of device tend to breakup any air
bubbles into fine voids.
↓
And strength of plaster is increased.
• Mechanical mixing time under vacuum approximately 20
seconds.
Setting Reactions gypsum products :
(CaSO4)2 H2O +3H2O → 2Ca So4.2H20 + Unreacted (CaSo4)2.1/2 H20
+Heat.
• The calcium sulphate heucihydrate powder reacts with the
water and produce the gypsum.

8. 1) When the hemihydrate is mixed with water, a suspension is formed
that is fluid and workable.
2) The hemihydrate dissolves until if forms a saturated solution.
3) This saturated hemihydrate solution, super saturated in dehydrate,
precipitates out dehydrate.
4) As dehydrate precipitates, the solution is no longer saturated with the
hemihydrate, so it continues to dissolve. Dissolution of hemihydrate
and precipitation of dihydrate proceeds as either new crystals form or
further growth accurse on the crystals already present.
The reaction is continuous and continues until no further dihydrate
precipitates out solution.
- The amhydrite is not formed in agueous media.
It is a exothermic reaction, heat is evolved and it is equivalent to heat
used in calcinations.
SETTING TIME
Type IV – 12 ± 4 minutes
Type V – 12 ± 4 minutes.
Control of Setting time :
1) Impurities :
• If the gypsum particles remain in the powder.
i.e. if calcination is incomplete
Or if manufacturer adds gypsum
Setting time is shortened because of the increase in the potential nuclei
of crystallization.
• If orthorhombic anhydrite is present → Induction period increases

9. • If hexagonal anhydrite is present → Induction period decreases.
2) Fineness :
 The Finer the particle size of the hemihydrate
Rate of hemihydrate dissolution increases
.
Rapid rate of crystallization occurs.
Mix hardens faster.
3) Water powder Ratio :
 If more water is used for mixing;
↓
Fewer nuclei are per unit volume;
↓
So the setting time is prolonged.
4) Mixing :
• The longer and more rapidly the plaster is mixed,
↓
Gypsum crystals formed immediately when the stone is brought in
contact with water
↓
As the mixing begins, the formation of crystals increases.
↓
During mixing the crystals are broken up and are distributed throughout
the mixture, resulting in the formation of more nuclei of crystallization.
↓
Thus the setting time is decreased.

10. Retarders and Accelerators :
 If the chemical added decreases the setting time, it is known as
accelerator.
 If the chemical added increases the setting time, it is known as
retarder.
Retaraders :
 Retarders act by forming a layer on the hemihydrate to reduce the
solubility.
 Ex : Glue, gelatin, some gums, borax, potassium citrate, concentrated
sodium chloride. (20%).
(If less concentration act as accelerator).
Accelerators
 Accelerator that are used mostly are –
Gypsum, potassium sulfate, sodium chloride is less concentrations.
Setting Expansions :
 Expansion of the mass can be detected during the change from
hemihydrate to the dihydrate.
 Crystals grow from nuclei and intermesh.
And obstruct the growth of adjacent crystals.
This process is repeated by thousands of crystals during growth
And outward stress or thrust develops
That produces an expansion of entire mass

11. Crystal impingement and movement result in production of micro
pores.
On drying, the excess water is lost
And void space is increased.
 Linear Expansion :
- Low – 0.06%
- High - 0.5%.
Control of Setting Expansion :
Sometimes a setting expansion is advantageous for a dental
procedure, sometimes it is disadvantageous, because it may be a source of
error. So setting expansion must be controlled to obtain the desired accuracy
in the dental applications.
- Low w/p ratio and longer mixing time increases the setting
expansion.
- Setting Expansion can be reduced by adding either potassium
sulfate, sodium chloride and Borax.
HYGROSCOPIC EXPANSION
The most well accepted reason for the increased expansion when the
hemihydrate reacts under water is the additional crystal growth permitted by
allowing crystals to grow freely rather than being constrained by the surface
tension when the crystals form in air.
Fig 10-8; pg 270 Phillips
In this theory -
1) In stage I the initial mix is represented by the three round particles of
hemihydrate surrounded by the water.
2) In stage II reaction starts, and crystals of dihydrate begins to form.

12.  In normal setting the water around the particles is reduced and
particles are drawn closely by the surface tension of the water.
 In the hygroscopic expansion, as setting takes place under
water the particles remains the same.
3) In stage III, in normal setting water reduced, particles are drawn
closely, but contraction is opposed by the outward thrust of growing
crystals.
 In the hygroscopic expansion – crystals are not inhibited, the water is
again replenished from the outside.
4) In stage IV and V-
 In normal setting the crystals are habited and become intermeshed
and entangled much sooner than hydroscopic setting.
 In hygroscopic setting the crystals are grown freely before
intermeshing and this inter meshing finally prevent the further
expansion.
So the expansion under water is more than that in the normal setting.
 The reduction in w/p ratio results the hygroscopic expansion
 In creased spatulation results in the hygroscopic expansion.
 The hygroscopic expansion during setting of the dental stone is
generally small in the magnitude.
Eg ; Normal expansion of dental stone may be 0.15% and
hygroscopic expansion of dental stone may be 0.30%. This difference
may be sufficient to cause the misfit of the denture or similar device
made on the cost/die.
STRENGDTH OF DIE MATERIALS
The strength of gypsum products is generally expressed in terms of
compressive strength, although tensile strength should also be considered in
order to secure satisfactory guide to the total strength characteristics.

13.  The strength of the plastu/stone increases rapidly as the material
hardens after initial setting time.
 The free water content of the set product definitely affects its
strength.
Table 10.5 pg 273 Phillips.
 The water traces at last leave fine crystals of gypsum to precipitate.
These fine crystals anchor the large crystals.
Then if water is added or if excess of water is present.
These small crystals are the first to dissolve
Thus the reinforcing anchors are lost.
 And also line of the w/p ratio is high, the greater is the porosity, the
fewer crystals are available per unit volume for a given weight of
hemihydrate; and the dry strength is less in the set material.
COMPRESSIVE STRENGTH
Mpa PSI W/p ratio
IV 34.5 5000 0.22-0.24
V 48.3 7000 0.18-0.22
Electro plated Dies/Electro formed Dies :
Besides resin, electro plating can be used to over come the poor
abrasion resistance of gypsom. The metal dies that are produced from
electroplated impression material have high strength, hardness and abrasion
resistance.

14.  Detail reproduction of a line 4 µm or less in width is readily
attainable when a non aqueous elastomeric impression material is
used.
 Variable degrees of distortion commonly occur, and the technique
must be performed slowly, other wise distortion in the metal will
subsequently stress the impression.
CERAMIC DIE MATERIALS
 Ceramic materials are supplied as a powder and liquid
They are mixed to a putty like consistency.
This material is placed over the impression
And removal from impression after 1 hour.
Then it is fired at 6000C for 8 minutes to produce a hard strong die.
Common brands :
 Ceramite H and V
 Cosmotech Vest.
 Ducera-Lay
 Doric HT2
 DVP Investment.
 V.H.T. Investment
 Vitadurvest.
Properties :
 Extremely abrasion-resistant.
 Some shrinkage on firing.
Applications :

15.  The prdoduction of dies for porcelain inlays, onlays and veneers.
METAL SPRAYING
 Many alloys and metals can be melted and dispersed in the fine
droplets with an oxy acetylene or other flame.
- These fine particles of molten metal or alloy can be sprayed on
to many dry materials with out burning.
- A Bismuth-tiss alloy which melts at 1380
C can be sprayed
directly on to an impression to form a metal shell.
- Then this is filled with the dental stone
 This method is applicable to the
- Elastomers.
- Impression compound.
 If the spraying is done slowly with care softessing of the compound
does not occur.
Advantages :
 Accuracy is good.
Disadvantages :
 The alloy is rather soft care is needed to prevent abrasion of the die.
 Special equipment is needed.

16.  Face mask must be worm to prevent inhalation of the fine spray of the
metal.
AMALGAM
 Amalgam may be packed into rigid impression materials such as
impression compound.
 The dimensional accuracy achieved depends upon the efficacy of
condensation and the dimensional changes of these materials.
Disadvantages :
 The this sections of impression compound occur in the impression
and these may be damaged on condensing the amalgam.
 There is a delay of 10-12 hours for the die to be hard enough to be
used.
 Location of dowel into the amalgam is not easy. So it is done later.
 Mercury hygiene should be practiced.
 Contamination of gold alloys by mercury can take place.
Procedure :
 An impression is made in a copper band with modeling compound.
 A this piece of boxing wax 28 to 30 guage is wrapped around the
impression and extended about 3/8 inch beyond and along gingival
margins of the band and impression.
The boxed impression is embedded in the mix of plaster in a small
rubber ring with the opens end showing the cavity facing up.

17. After plastic has hardened then plastic mass of amalgam is condensed
into impression.
After setting the rubber ring and plaster is removed and the die is
immersed in warm water to remove the impression compound and
wax.
Impressions of upper and lower arches is takers.
Then amalgam die is placed in the impression of prepared tooth and
cast is poured.
Precaution :
Amalgam dies and all metal dies are good conductors of heat and so
softened wax applied to them cools rapidly.
This rapid cooling of wax may produce internal stresses, which can cause
distortion of wax pattern.
So warming the metal die to mouth temperature or slightly below should be
done.
Polymeric Materials :
1) Auto – polymerizing Acrylic :
 The self-cure acrylic is used as die material and it is fabricated in the
same way like the fabrication of the self cure dentures.
Disadvantages :
 The monomer reacts with all except silicone impression materials.
 The heat of reaction distorts thermoplastic materials.
 Volumetric contractions takes place.

18. All these disadvantages makes the material unsuitable as a die material.
2) Filled Polymeric Materials :
Ex ;
 Epoxy Resins.
 Polyesters
 Epimines
 Poly urethane resins.
They are available as liquid and powder and postes; one of which is
either liquid monomer or unsaturated polymer like epime, epoxy, poly ester
or poly urethane resins and the other component may contain powdered
polymer particles and a suitable initiator or activator for polymerizing or
cross linking the fluid phase to produce a solid. Either of them may contain
an inert metallic or ceramic filler.
Common brands :
 Diemet
 Goldex
 Impredur.
 Polyroqq.
Manipulation :
 The constituents are mixed according to manufacturer’s
recommendations into homogenous paste.
Mixing time is 1 minute.
The paste is then vibrated into the impression.
Some elabtomers require coating with a separating medium; often
finely powdered metal.

19. Applications :
The production of dies from those impression materials with which
they are compatible, generally elabtomers coated with separating medium.
Advantages :
 Rapid set (1hour)
 More abrasion resistant.
 Not as brittle as die stones.
 Better reproductions of the details.
Disadvantages :
 Shrinkage (0.02-0.6%) on polymerization may be a source of
inaccuracy-fillers reduce this shrinkage.
 Water retards polymerization of resing-so epoxy resins can not be
used with water containing agar and alginate impression materials.
Advances of epoxy materials :
 Recently fast setting epoxy materials have been supplied in
automixing systems similar to those for automixing addition
silicones.
 The epoxy resin is in on cartridge and the catalyst is in the other.
 Forcing the two pasts through the static mixing tip thoroughly mixes
the epoxy material which can be directly injected into a rubber
impressions.
REFRACTORY MATERIALS
There are advantages, of the die, together with its pattern, can be used
directly for casting. This eliminates possible errors in the shape of the
pattern on removing it from the die.
The gypsum bonded material is available for gold castings. The use of
phosphate bonded investment materials has also been suggested for high
fusing alloys.

20.  A commercial gypsum-bonded material is available for gold castings.
The use of phosphate bonded investment materials has also been
suggested for high fussing alloys.
 A commercial gypsum-bonded material called divestment is mixed
with a colloidal silica liquid.
The die is made from this mix and the wax pattern is constructed on
it.
Then the entire assembly (die and pattern) is invested in the
divestment to eliminate the possibility of distortion of the pattern
upon removal from the die or during the setting of investment.
Precautions :
 special seperator is used with polysurfides.
 With out seperator the colloidal silica softens the elastomers and the
die sticks firmly to impression.
 It may lead to the destruction of the master die.
Properties :
 Compressive strength – 45-50 N/mm2
.
 Setting time – 15 min
 Setting expansion – 1%
 Thermal expansion – 0.3%
 Hygroscopic expansion – 0.3%.
DIE SYSTEMS :
In the fabrications of the wax pattern, it is used to establish inter
proximal contacts, buccal and lingual contours and occlusion with the
opposing teeth. The die is a model of the Individual prepared tooth on which

21. the margins of the wax pattern are finished. There are two basic working
cast and die systems-
1. Working cast with a separate die.
2. Working cast with a removable die.
1. Working cast with a separate die :
The working cast and the sectional cast for the die can be obtained
from separate impressions or by pouring an impression twice.
 The first cast is used for preparation of the die this
procedure (double pour) can be used only with elastomeric
impressions, since hydrocolloid is form and distorted too much to
be used for an accurate 2nd
pour.
Procedure :
1. Impression pouring is done
with the type IV /type die materials.
2. Build up the stone to height of
approximately 1 inch (2.5 cm) over the preparation to allow bulk for
an adequate handle on the die.
Fig 18.3 pg : 310 shillinburs
3. Carefully separate the poured
cast from the impression
4. A material such as Super-Sep
(kerr) may be painted on the surface of the prepared tooth to guard
against surface erosion. (Liquid/Latex).

22. 5. Trim the cast from which the
die is made on a model trimmer to remove all excess stone around the
prepared tooth.
Fig 18.4 pg 311-shillin
6. The handle of the die should
be slightly larger in diameter than the preparation and octagonal in
cross section.
Fig 18.5 pg 311-shillin
7. Sides should be parallel or
slightly tapered towards the base.
 Handle should not be angled. (Fig 18.6-311
shill)
8. The handle should be approximately 1 inch long.
Fig 18.7-312-shillin
9. Use a pear shaped bur to trim the die apical to the
finish line of the preparation.
Fig 18.8-312 shillin
10. Finally trim the die with No.25 blade
Fig 18.9-312 shill
11. Smoothers below the finish line with discoid end of
tanner carver.
Fig 18.10-312 Shillin.
12. Die contours should be maintained similar to those of
natural tooth.
Fig 18.12 313 shillin
13. should not have any sharp under cuts or ditching as
instrument used for finishing the margins of the wax pattern will rest

23. against this portion of the die and this will result in thick gingival area
as the restorations that is not good for gingival health.
Fig 18.13 313.
14. The finish line should be highlighted with a sharp colo
bite red pencil that facilitate carving of the wax pattern.
Fig 18.14 313 shillin
15. Relief should be applied to the preparation area of the
die to provide space for cement.
Usually used relief’s
– Enamels
– Lacquers.
Desired thick ness – 20-40 µm.
Should be painted 0.5 mm above the finish line.
Fig 18.15-314 shillin
16. A die hardening agent is applied to finish line area of a
die to prevent abrasion by waxing instruments.
Cyno acrylate – 1-25 µm
(or)
Acrylic lacquers – 4-10 µm
17. Then the wax pattern prep. Done.
Advantages :
 Ease of falorication.
 Keeps relationships between abutments fixed and
immovable.
 Because the gingival tissue and other land marks
are intact, it is easier to obtain physiologically harmonious
restoration contours when fabricating the wax pattern.

24. Disadvantages :
 Use of working cast with a separate die is that the
wax pattern must be transferred from one to the other an din this
process they destroy some of the internal adaptation of the wax
pattern.
2. WORKING CAST WITH A REMOVABLE DIE :
Requirements :
1) 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.
Several methods can be employed to allow the repositioning of a die
in its working cast. Most of these devices can either be oriented in the
impression before it is poured i.e., pre-pour technique (or) attached to
the under side of a cast that has already been poured.
 Removable Die Systems –
1) Straight dowel pin.
2) Curved dowel pin.
3) Pindex System.
4) Die-lok tray.

25. 1. STRAIGHT DOWEL PIN :
 Impression is taken.
 Orientation of the dowel pin can be done by the
anesthetic needles, paper clips and bobby pins.
 Dowel pin is placed in between the arms of the
bobby pin. Then this bobby pin is positioned bucco-lingually
across the impression, so that the dowel pin will be centered
directly over the preparation.
- Push the straight pins into arms of the bobby pin and into the
impression material on both buccal and lingual surfaces. Stabilize
the dowel pins and straight pins with bobby pins with the sticky
wax.
Fig 18.8 pg-316 shillins
 Then pour the die stone into the impressions of the
teeth. The pins should be straight and not touch the impression.
Fig 18.19 pg 316
 After impression had set remove bobby and
straight pins place a utility wax at the tip of dowel pin as an aid in
locating dowels after the base has been poured.
- Lubricate the stone around each dowel with a thin coat of
petrolatum or seperating medium to permit easy seperation of the
dies from the working cast later.
Fig 18.20 pg 316 shillin
 Place a wet paper towel into the open lingual
space to enable complete base for the cast to be poured.

26. Fig 18.21 pg316 shillin
 Use a sharp knife to uncover the utility wax
Fig 18.22 pg 317
 When the stone is hard and dry use a saw frame
with a thin blade to cut mesial and distally through the layer of die
stone. The cut should taper towards gingivally.
Fig 18.23-317
 Gently tap the dowel with instrument tip to loosen
the die.
Fig 18.24-317 shi
 Take the die from the cast and tries away excess
stone gingivally to the finish live.
Fig 18.25-318 shi
 Reseat the dies to make certain that they will seat
completely and will be stable.
Fig 18.26-318
 Place wax around the tips of dowels and there
mounted on to the articulator using mounting stone.
 Then wax is removed from the ends of the dowel
pins.
2. CURVED DOWEL PIN.
Curved dowels can be incorporated into a working cast by fixing the
dowels to the impression before it is poured or by cementing the dowels into
the holes drilled in a previously poured cast.
i) Installing the pins before pouring :

27.  To install pins before pouring the impression, use
finger pressure to insert a curved dowel tip into the large opening
in the positioning bar.
 Bar is oriented taciolingually so that dowel
extends 1-2 mm into impression of prepared tooth.
 Place straight pins facio lingually to stabilize bar.
Fig 18.28 pg : 319.
 After die has hardened straight and positiong bar
are removed. Depressions are made about 2 mm deep by acrylic
bur on either side of dowels that will assist in orienting the
unprepared tooth.
Fig 18.29 319
 This coat of petrolatum is applied to the stone and
dowels.
Fig 18.30 - 320
 Boxing wax is placed around the impression, with
the tips of the dowels sticking through.
Fig 18.31 - 320
 Then the cast is sectioned.
Fig 18.32 - 320
 Segment is removed by pressing on the exposed
tip of curved dowel with knife handle or other instrument.
Fig 18.33 – 320 shillin
ii) Placing the pins after the Impression pouring :
 Pour the impression with a die stone to form a
horse-shoe shaped working cast. Trim the bottom of the cast flat
on model trimmer so that not more than 10 mm from the necks of
the teeth.

28. Fig 18.34 pg :320
 Drill 5 mm deep hole with hand piece or drill
press (pindex) in the bottom of the cast directly under the center of
each prepared tooth, pontic area and segment containing
unprepared teeth.
Fig 18.35 pg : 320
 If the removable segment is larger than width of
two teeth, the stone on each side of the dowel hole should be
keyed to a depth of 2 mm with large acrylic bur.
Fig 18.36 pg : 321
 A drop of cyno acrylate cement is placed into each
of the drilled holes.
Fig 18.37 Pg : 321
 The head of a curved dowel is seated into the
cement lined hole and tipes are faced facially.
Fig 18.38 pg : 321
 A curved dowel is cemented into each removable
part and thus the boxing is done. Base is poured and dies are
separated as explained previously.
Fig 18.39 pg : 321
3. PINDEX SYSTEM
In the pindex system a reverse drill press is used to create a master
cast with dies that can be removed or replaced repeatedly.
 Impression is poured without positioning dowel
pins.
Fig 18.41 pg : 322

29.  After impression is set, wet it and trim with model
trimmer.
Fig 18.42 pg : 322
 The cast should be 15 mm thick, exclusive of the
teeth.
Fig 18.43 pg : 323
 Periphery and tongue area should be trussed.
Fig 18.44, 18.45 – Pg : 323
 Location of pin holes is marked with the pencil.
Fig 18.46 pg : 324
 Switch on the pindex macline. A red pilot light
will indicate that it is running.
Fig 18.40 pg : 322
 Place the prepared cast on the work table and align
the pencil mark with the light beam director.
Fig 18.47 pg : 324
 Raise the handle bar with slow pressure ford 3-5
seconds. And when proper depth has reached the red pilot light
will go off indicating hole is finished.
Fig 18.48 pg : 324
 Debris is removed from the pin holes with a brash.
Fig 18.49 pg : 324
 Use a hand reamer to remove debris from the pin
holes.
Fig 18.50 pg : 324
 Cyno acrylate cement is placed on the pins prior to
cementing the tips. Fig 18.51 pg : 325
 Shorter pins are placed first, there longer pins.

30. Fig 18.52 pg : 325
 White slews are placed on long pins and gray
sleeves on the short pins. Fig 18.53
pg : 325
 Utility wax is place on the ends of the long pins to
facilitate removal of dies wax is filled over the gray slever to
prevent the filling of the stone into sleves.
Fig 18.56 pg : 325
 A palatal/tongue filler is made by boxing wax.
Fig 18.59 pg : 326
 Boxing wax is applied around the cast.
Fig 18.60 pg : 326
 Thus the base is poured
Fig 18.61 pg : 326
 Wax is removed and sectioning of the die and die
preparation and mouting are same as the previous procedures.
4. Di-LOK TRAY
 A snap-apart plastic tray with internal orienting
grooves and notches also can be used to reassemble the working
cast and die.
 Before using the tray for a given case, examine the
mounting of the diagnostic casts on the articulator to determine
weather there is space for the bulky tray.
 Pour the entire full arch impression with die stone
and it should be poured in a U-shape with no stone in the center.
Fig 18.72 pg : 330
 The lingual side and base are trimmed. With arbor
band.

31. Fig 18.73 pg : 330
 Horizantal grooves are cut in the base to give it
retention.
Fig 18.74 pg : 330
 Stone is poured into the tray and cast is placed into
the tray teeth should be 4 mm above the tray.
Fig 18.75 pg : 331
 To complete the dies, the cast must be removed
from the tray.
Fig 18.76 pg : 332
 A saw cut is made on each side of the prepared
tooth.
Fig 18.78 pg : 332
 The prepared tooth is broken free from the cast by
finger pressure.
Fig 18.79 pg : 332
 Trim the die as previously
Fig 18.80 pg : 333
 Slide the buccal facing on to the base of the tray
from front place the back down over the lugs on the buccal facing,
locking the tray together.
Fig 18.81 pg : 332
 The wax pattern and mounting as explained
previously.
Fig 18.82 pg : 333
************

32. 5)