3. Contents
Definition
Requirements of an Impression Material
Properties of Impression Material
Classification of Impression Material
Classification of Inelastic Impression Material
Impression Compound
Zinc Oxide Eugenol Impression Paste
Impression Plaster
Impression Waxes
Review of literature
Conclusion
References3
4. Definition
Impression.
An imprint or negative likeness of the teeth and/or edentulous
areas where the teeth have been removed, made in a plastic
material which becomes relatively hard or set while in contact with
these tissues. Impressions may be made of full complements of
teeth, of areas where some teeth have been removed, or in mouths
from which all teeth have been removed. (Impressions are
classified according to the materials of which they are made, such
as reversible and irreversible hydrocolloid impression, modeling
plastic impression, plaster impression, wax impression, silicone
impression, Thiokol rubber impression). GPT(4)
It is the negative likeness or copy in reverse of the surface of an
object, an imprint of the teeth and adjacent structures for use in
dentistry. (GPT-9)
4
5. Impression materials-
Any substance or combination of substances used for
making a negative reproduction or impression.
(GPT-9)
Impression materials are used to register and reproduce the
forms and relationships of teeth and associated oral tissues.
(Shama Bhat 2nd edition )
5
6. Requirements Of An Impression Material
They should :-
Be fluid enough to adapt to oral tissues.
Be viscous enough to be contained in the tray that is seated
in the mouth.
While in the mouth they should transform into a rubbery or
rigid solid in a reasonable amount of time.
Set impression should not distort or tear when removed
from mouth.
Philips’Science Dental Materials-Anusavice-11th Edition-Elsevier :2076
7. Impressions made from these materials should remain
dimensionally stable at least until the cast can be poured.
The impression should maintain its dimensional stability
after removal of a cast so that second or third cast can be
made from the same impression.
The materials should be biocompatible.
The materials, associated processing equipment, and
processing time should be cost-effective.
Philips’Science Dental Materials-Anusavice-11th Edition-Elsevier :2077
8. General Properties of Impression Material
Biocompatibility And Chemical Properties
Non poisonous,non irritant,non allergic to oral tissues.
Chemically inert
Hydrophilic
Compatible with die or cast material and pattern waxes.
Acceptable taste and odour for patient.
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9. Rheological Properties
Low viscosity while inserting for finer details.
Viscosity should increase quickly to avoid distortion.
Pseudoplastic nature – increase flow by stressing for better
details.Example:monophase additional silicones.
Suitable mixing and working times by controlling the rate of
chemical reaction.
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10. Plastic-
Fluids exhibits rigid behaviour initially and then attain constant
viscosity.
Pseudo plastic-
Characteristic nature of material to become more fluid when
applied force is increased ; this behaviour involves shear
thinning and is strain rate-dependent.
Thixotrophic –
Property of certain gel or other materials to become liquefied
when shaken, stirred, patted or vibrated.
Philips’Science Dental Materials-Anusavice-11th Edition-Elsevier
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11. Mechanical properties
High elasticity and complete elastic recovery.
Addition polysilicones-99.93%
Adequate compressive strength to avoid dimensional changes.
High tear strength to withstand tearing or shearing stresses
during impression removal.
Least- Hydrocolloids -750gm/cm to 800 gm/cm
Highest-elastomers-2000gm/cm-4000gm/cm
High flexibility or strain in compression is needs to permit
withdrawal
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12. Thermal properties
Low softening temperature (45-55°C) and sets by 37°C.
Very low or zero coefficient of thermal expansion to minimise
contraction .
Very High Coefficient – Large Contraction
High thermal conductivity to soften or harden or set the
impression simultaneously.
Properties should not change while kneading at high
temperature.
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13. Aesthetic Properties
Good colour contrast to identify margins.
Fairly good colour stability
Two paste systems have one paste coloured to
check uniform mixing.
Elastomers have different colour so that they can be
identify for consistencies.
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15. Depending On Chemical Composition
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Impression
plaster
Impression compounds
Elastomers
Impression waxes
Hydrocolloids
Zinc oxide eugenol
paste
Alignate Agar Agar
PolysulphidesPolyethers Polysilicones
15
16. Depending On Mechanical Properties
Impression Materials
-ZOE paste
- Impression plaster
-Impression compound
- Impression waxes
InelasticElastic
Elastomer
Polyether
Polysulphide
Silicone -
Condensation
And
Addition
Hydrocolloid
-Agar agar
-Alginate
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17. Depending On Force Exerted On Soft Tissues
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Mucostatic Mucocompressive
Impression plaster
Agar agar
Light body elastomers
Zinc oxide eugenol
paste
Impression compound
Viscous alginate
R,H,P consistencies of
elastomers
18. Depending On Setting Mechanism
-Plaster of paris
Impression Materials
Chemical reaction
Thermally induced physical
reaction
-Non aqueous
elastomers
Polysulphide
Polyether
Polysilicone
-Alginate
Hydrocolloid
-Zinc oxide eugenol
-Impression wax
- Agar
Hydrocolloid
- Impression
Compound
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26. Impression compound is a mucocompressive, rigid,
reversible material which sets by temperature change.
CLASSIFIED AS:-
Type 1 – Impression compound
Which is generally used for making an impression
of the edentulous ridges.
Type 2– Tray compound
It is more viscous compound and can be used to
form a tray for construction of a denture.
26
27. According to ADA specification no 3
◦ Type 1-
Low fusing compound (above 45°C)
- Green stick compound
- Impression compound
◦ Type 2-
High fusing compound (above 70°C) -Tray compound
27
30. Uses
1. For making preliminary impression in an edentulous
mouth.
2. For individual tooth impression.
3. Border moulding (Green Stick)
4. To check the undercuts in inlay preparation.
5. To prepare a special tray (Tray Compound)
30
31. Ingredient Percentage Function
1.Natural Or Synthetic
Resins
a) Copal Resin
b) Rosin
20%
20%
Thermoplasticity and gives flow and
cohesions.
2.Waxes:-
(Bees Wax, Carnauba Wax
Or Paraffin Wax)
7% Thermoplasticity & produces smooth
surface.
3.Various Types Of Oils
And Fats:-
(Stearic Acid, Shellac
,Gutta Percha)
3% Plasticizer to improve the flow, plasticity,
workability, and hardens the compound.
4.French Chalk, Talc,
Diatomaceous Earth
50% -To improve the strength
-To reduce thermal expansion & contraction
5.Rouge (Ferric Oxide) Traces Mainly as color pigment, provides reddish
brown colour to compound.
Composition
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33. Properties Of Impression Compound
Glass Transition Temperature:-
Definition: Temperature at which the material looses
its hardness or brittleness on heating and forms a rigid
mass on cooling is referred as Glass transition
temperature.
- It is approximately 39 °C for impression compound.
33
34. Significance-
- Once the impression tray is seated, it should be held
firmly in position until first fusion temp. and later glass
transition temperature is reached.
- Thus, the impression is made above the fusion temp.
whereas it is removed from the mouth only after it cools
down to its glass transition temperature
34
35. Fusion Temperature
Definition : The temperature below which a definite
reduction in plasticity occurs during cooling of impression
compounds.
-For Impression compound it is approximately 43.5 °C
-For tray compound it is approximately 65 to 70°C
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36. Significance
- It is a temperature at which crystalline fatty acid melts.
- So, above this temp. the fatty acids are liquid and
lubricate the softened material to form a smooth and
plastic mass, while the impression is being obtained.
-Thus, all the impression with compound should be made
above this temperature.
-Below, this temp. an accurate impression can not be
expected
36
37. Thermal conductivity :-
-Poor conductor of heat .
-Average linear contraction of impression
compound 25°C is 0.3-0.4%
Flow :-
- highly viscous and mucocompressive
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38. According to ADA specification No. 3
• Type I : flow not more than 6% at 37 °C.
flow not less than 80% and not more
than 85% at 45 °C.
• Type II : flow not more than 2% at 37 °C
Flow not less than 70% and not more than
85% at 45 °C
38
39. Dimensional stability
-Residual mechanical stresses are incorporated in
impression compound during heating, manipulation and
recording impression.
-Distortion may occur during storage period due to
relaxation of these stresses.
-For accurate results model should be poured as soon as
possible.
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40. Manipulation
It is softened in warm water in a thermostatically
controlled water bath(Range 60°C -70°C)
After the compound is removed from water bath, it is
usually kneaded with the finger in order to obtain
uniform plasticity throughout the mass.
Then it is placed in non perforated stock tray.
After the compound is moulded to the shape of
impression tray it is inserted in to the mouth and held
gently in position until the impression cools.
40
42. It is then removed and checked for any fracture or
deformation.
Then cast should be poured without delay.
The cast should be separated from the impression by
immersing it in warm water after the stone sets.
42
43. Kneading
There are two techniques of kneading:-
1 Wet kneading (more common)
2 Dry Kneading
The technique of softening consists of submerging the
compound in water bath is known as a wet kneading/
Green stick compound is softened by warming over a
gas flame and then kneaded is known as a dry kneading
technique.
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44. Precaution To Be Taken During
Manipulation
The compound should not be allowed to boil or ignite ,
otherwise the plasticizers are volatized.
Prolonged immersion in a water bath is not indicated, as
the compound may become brittle and grainy because
some of the low molecular weight ingredients may be
leached out.
Overheating leads to sticky compound and difficult to
handle.
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45. Avoid incorporating of water while kneading; it
increases flow after hardening.
Impression is removed from the mouth only after it has
completely hardened.
During cast separation excessive hot water is also
avoided as it can make the material sticky and difficult
to remove from cast.
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46. Green stick compound
Supplied in cylindrical form about 10cm in length and
6mm in diameter
Fusion temperature - 43°C-45°C
Used for –
1. Border moulding of special tray
2. Copper tube impression technique
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47. Border moulding technique
Used for recording functional depth of sulcus
2 methods -single step border moulding
-sectional border moulding
47
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48. Procedure
1. Green stick is heated uniformly over flame
2. Applied over special tray borders
3. Tempered in water bath and put inside patient mouth.
4. Different movements of jaw is done
5. Removed after it hardens
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49. Heating of green stick over a flame
Adapting green stick over a special tray
Picture courtesy: Department Of Prosthodontics Darshan Dental College And Hospital, Loyara
49
50. Advantages
1. Non irritant and non toxic.
2. Reusable and economical.
3. Can be added and readapted.
4. Used in combination with other material.
5. Long shelf life about 5 years.
50
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51. Disadvantages
1. Poor dimensional stability.
2. Poor surface detail.
3. Large coefficient of thermal expansion and poor
conductor of heat.
4. Non elastic and cannot be used when undercuts exists.
5. Compress the soft tissue while making an impression.
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52. Disinfection
2% Alkaline Glutaraldehyde solution, sodium
hyopochlorite and iodophors.
Impression is immeresed, rinsed and poured.
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53. Storage
The cast should be pored as soon as possible within first
hour to minimise distorartion due to relaxation of the
impression compound
Prosthetic treatment for edentulous patients:complete dentures and implant supported prostheses:
ZARB.HOBKIRK.ECKERT.JACOB. :Edition 13th 53
55. Zinc Oxide Eugenol Impression Paste
Mucostatic, inelastic, chemically setting impression material,
used for recording secondary or corrective wash impressions of
edentulous arches in the preperation of complete dentures.
Synonyms:
Metallic oxide pastes
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56. CLASSIFIED AS
According to ADA specification no 16
Type 1 – Hard set, fast set, thinner consistency
Type 2 - Soft set, slow set, thicker consistency
Supply As:
In paste form in two tubes
Base paste (white in color)
Accelerator or Reactor or Catalyst paste (red)
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58. Uses-
As an impression material for edentulous mouth
A surgical dressing
Bite registration paste
Temporary filling material
Root canal filling material
Cementing medium
Temporary relining material for dentures
Stabilising denture.
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59. Composition-
Ingredient Percentage Function
ACCELERATOR PASTE
a) Oil of cloves or eugenol 12%
Reactive Ingredient
b) Gum or polymerized rosin 50% a)Facilitate the speed of reaction
b)Give smooth and homogenous mix
c)Thermoplastic property
c) Filler(silica ,kaolin,talc) 20% Improve Strength
d) Lanolin 3% Plasticizer
e) Resinous balsam 10% Increase flow and improve mixing
qualities
f) MgCl2or CaCl2 5% Accelerators
g) Colour pigments traces a)Distinguish from other paste
b)Enables thorough mixing 59
60. Ingredient Percentage Function
Base paste
a) Zinc oxide 87% Reactive ingredient
b)Fixed vegetable or
mineral oil
13% Paste former
plasticizer,retarder,masksth
e irritation of eugenol
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61. Setting Reaction
It is a typical acid-base reaction to form a chelate
This reaction is also known as CHELATION
End product is called zinc eugenolate
Zno+H2O ZN(OH)2
Zn(OH)2+2HE ZnE2+2H2O
BASE ACID ( ZINC EUGENOLATE)
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62. ZnO combines with water to give zinc hydroxide, zinc
hydroxide react with eugenol to give zinc eugenolate salt.
Water formed is utilised in further reaction- auto catalytic
reaction
The setting reaction is ionic in nature and ionic medium is
increased by the presence of certain ionisable salts which act
as accelerator(acetic acid, sodium acetate etc.)
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63. Properties
Setting time :-
INITIAL Setting time :-
Is the period from the beginning
of the mixing until the material ceases to pull away or
string out when its surface is touched with a metal rod of
specified dimension.
Setting Time Initial Final
Type 1 3-6 min <10 min
Type 2 3-6 min <15 min
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64. FINAL Setting time :-
Time elapsed from start of mixing to the
instant when penetration falls below 0.2 mm as measured with
penetrometer or similar instruments.
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65. Hardness-
Definition: Resistance of a material to plastic deformation typically
measured under an indentation load.
Kreb’s penetrometer is used to find the hardness of set material.
Penetrometer is equipped with a needle of 50.8 mm in length,
1.02 mm in diameter, and the total weight of the needle is 100
gms.
30 min after the start of mix, the loaded needle is applied to the
specimen surface for 10 sec and penetration is recorded to the
nearest 0.1 mm.
Penetration hardness for type I is <0.5 mm
type II is between 0.8 to 1.5 mm
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66. Rigidity and Strength :-
7 Mpa after 2 hrs from start of mixing
Dimensional stability :-
Negligible dimensional change during setting (less than 0.1%)
Biological consideration :-
Eugenol can cause- tissue irritation burning sensation
Mucostatic and gives accurate and finer details.
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67. Factors affecting setting time
INCREASE IN SETTING TIME:-
By using cool spatula and mixing slab
More ZOE paste
Retarders(inert oil and waxes)
Slower & shorter mixing time
DECREASE IN SETTING TIME:-
Higher Temperature, humidity
More eugenol paste
Drop of water
Accelerator(Cacl2, Mgcl2)
Longer and faster mixing time 67
68. Manipulation
Mixing is done on glass slab or oil impervious paper
Two ropes of paste of same length and width, one from each
tube are squeezed onto the mixing slab
Picture courtesy: Department Of Prosthodontics Darshan Dental College And Hospital, Loyara
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69. A flexible stainless steel spatula is used
Two ropes are combined with the 1st sweep of the spatula and
mixed until a uniform color is observed
Picture courtesy: Department Of Prosthodontics Darshan Dental College and Hospital, Loyara
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70. Mixing time-1 min
PRECAUTION TO BE TAKEN:-
A paste of a thick consistency can compress the tissue.
Whereas a thin fluid material result in an impression that
capture a negative replica of a tissue in a relaxed condition with
little or no compression.
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72. Advantages
It has enough working time to do border moulding.
Easy to manipulate, not very expensive.
It registers accurate surface details .
It is dimensionally stable .
It does not require any separating media as it does not stick to
cast.
Adherent well to dried surfaces of compound, resin and shellac
bases.
Have sufficient resistance so that borders can be built up if the
tray is slightly deficient in any area.
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73. Disadvantages
It requires a special tray for impression making.
It adheres to tissues .
Eugenol can cause burning sensation and tissue irritation .
It can not be used for making impression of teeth and
undercut areas as it is inelastic in nature.
Instruments are difficult to clean.
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74. Disinfection
Glutaraldehydes or iodophors.
Immersion prefered; spraying can be used for bite registration.
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75. Modification -Non-eugenol Paste
Burning sensation is one of the most common disadvantage of
eugenol
Zinc oxide can reacts with various carboxylic acids and form
ZOE like materials
ORTHOETHOXYBENZOIC ACID (EBA) is a suitable
substitute for eugenol
ZnO+2RCOOH (RCOO)2Zn+H2O
Reaction can not affected by temp. and humidity.
Bactericides and medicaments can be added. 75
76. Surgical Pastes
After certain periodontal surgeries (e.g. gingivectomy)where
a suture can not be placed
A ZOE surgical paste may be placed over the wound
-To aid in retention of medicament
-To protect the wound
-To promote healing
These pastes are generally slower and softer in their setting
reaction in comparison with impression pastes.
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77. Drawbacks
i) Chronic gastric disturbance ,if kept for longer duration.
ii) Irritation and burning sensation is produced.
Surgical pastes
77
78. Bite registration pastes
ZOE paste used as recording material in construction of
complete denture and fixed or removable partial dentures
It offers almost no resistance to closing of mandible, thus
allowing a more accurate interocclusal relationship records.
The composition is similar to conventional ZOE impression
paste with slightly more plasticiser added.
78
79. Impression plaster was one of the earliest impression materials in
dentistry.
It is a rigid, mucostatic impression material that sets by chemical
reaction.
It is Calcium Sulphate β- hemihydrate obtained by modifying the
model plaster by adding small amount of uncalcined gypsum and
calcium sulphate anhydrite.
79
81. For making final impression of edentulous patient with
displaceable soft tissue to be recorded in passive state.
Bite registration to record centric record and protustive record
Prosthetic treatment for edentulous patients:complete dentures and implant supported
prostheses: ZARB.HOBKIRK.ECKERT.JACOB. :Edition 13th 81
82. According to ADA specification no 25
Ingredient Percentage Function
Potassium Sulphate 4% Accelerator:acts by decreases the setting time
and setting expansion.
Borax 0.4% Retarder increase setting time and decreases
setting expansion
Uncalcined dihydrate
and small amount of
anhyrites
Accelerators -impurtities
Coloring agent Alizarin red is commonly used.
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83. Mixing Time:- Hand Mixing:- 1 Min
Mechanical Mixing:-20-30 SEC
It’s a time from the addition of the powder to the water
until the mixing is completed.
Working Time:- 3 Min
Time available to use a workable mix.
Setting Time:- 4+1 MIN
It is a time elapsing from the beginning of the mixing until
the material hardens is known as a setting time.
83
84. Setting Expansion:-
- An expension of the mass can be detected during the change
from hemihydrate to the dihydrate.
-2 hour setting expansion:- MAX 0.15%
Increase in w/p ratio leads to decrease in setting expansion
-Addition of borax, potassium sulfate and sodium chloride
reduces the setting expansion.
84
85. Strength:- 4-5 MPa
Low strength helps to separate impression from the cast by
fracturing.
85
86. 1.Proportioning & Mixing:-
-Impression plaster should be mixed in a rubber bowl using a
stiff, wide bladed spatula.
-The material is used at a higher W:P ratio than is normally
used for modeling plasters.
-The fluid mix is required to enable fine detail to be recorded
in the impression & to give the material mucostatic properties.
86
87. W/P RATIO:-
0.45 TO 0.75
Increase W/P RATIO:-longer is the setting time and
weaker will be the gypsum product.
87
89. 2. Impression Making:-
- Freshly mixed plaster is too fluid to be used in a stock
impression tray & is normally used in a special tray,
constructed using a 1-1.5mm spacer. The tray may be made
from acrylic resin or shellac.
- Another technique is to record the plaster impression as a wash
in preliminary compound impression.
- The compound is deliberately moved during setting to create
space for the plaster wash.
89
90. One technique for recording impressions of undercut areas,
commonly used before the advent of elastic materials, was to
allow the impression plaster to set & then to fracture it in order
to facilitate removal from mouth. Material is weak & easily
fractures due to high W:P ratio.
90
91. 3.Separating Media:-
-Alcoholic solutions of varnishes & waxes, soap solutions,
water glass( 60% solution of sodium silicate in water), liquid
paraffin & a variety of commercial preparations may be used.
4.Disinfection:-
-Impression plaster may be immersed for 20min in 2%
IODINE solution
91
94. Good surface detail
Negligible dimensional changes
Rate of the setting reaction can be controlled by the clinician
94
95. Separating medium is required.
Tend to fracture when removing from undercuts.
Non toxic but cause dryness.
Bad taste- disliked by patients
95
96. Impression plaster may sometime contain ‘POTATO
STARCH’ to make it soluble and this type is often known as a
‘soluble plaster’
After the cast has hardened, the impression and cast are put in
hot water.
The starch swells and the impression disintegrates, making it
easy to separate the cast from the impression.
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97. Impression Waxes
Waxes were first used in dentistry in the early 18th century for
the purpose of recording impressions of edentulous mouths.
DENTAL WAXES:-
A low molecular weight ester of fatty acids
derived from natural and synthetic components such as
petroleum derivatives that soften to a plastic state at a
relatively low temperature.
97
98. • Waxes are thermoplastic materials, which flow at mouth
temperature and are relatively soft at a room temperature.
They do not set by chemical reaction.
• Many varieties of waxes are used in dentistry as important
auxillary materials in clinical and laboratory procedures for
processing and pattern making, for fabrication of oral
appliances.
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99. • Generally used in combination with other impression material
such as
Polysulfide
ZOE impression paste
Impression compound.
• Generally used to record non undercut edentulous portion of
mouth.
99
101. Classification: According to ADA sp no 4
ACCORDING TO ORIGIN:-
• NATURAL:-
Mineral
Plants
Insects
Animal origins
• SYNTHETIC WAXES
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102. According to application
• PATTERN WAXES:-
Inlay Type 1
Type 2
Casting
Base plate Type 1
Type 2
Type 3
• PROCESSING WAXES:-
Boxing and beading
Sticky
Block out
Utility
Carving
• IMPRESSION WAXES:-
Corrective impression
Bite registration
102
103. • Trade names Iowa wax:.white: developed by Dr Earl S. Smith
Korecta wax no: 4. Orange Dr.O.C. Applegate
H-L physiologic wax. : yellow –white: Dr.C.S. Harkins
Adaptol : green: Nathan G. Kaye
103
Korrecta wax
104. General properties
Thermal Properties:-
• Melting Ranges:-
o Waxes consists of several types of molecules with different
molecular weights.
o So, they have a melting range rather than a melting point.
Paraffin Wax:-44°C-62°C
Carnauba Wax:-50°C -90°C
o By varying the composition or by mixing other varieties, it is
possible to change these ranges according to use.
104
105. • Thermal expansion
- Waxes expand when subjected to a rise in temperature and
contract as the temperature is decreased.
- Dental waxes and their components have the largest Coefficient
of thermal expansion among the materials used in restorative
dentistry.
150-400 ppm/°C
- Temperature changes in wax patterns after removal from mouth
leads to contraction of wax patterns about
0.3%-0.8%
• Thermal Conductivity
All waxes are poor conductors of heat
105
107. Mechanical properties:
Flexibility and Modulus Of Elasticity:-
-These related properties change with rise of temperature and
composition.
-Increase in temp. from 23°c to 37°C
-Decrease in proportional limit from 11.0 MPa to5.5 MPa in
MOE from 1790 MPa to 760 MPa
107
Science of Dental Material Science of Dental Materials Clinical applications-V Shama.BT
Nandish-2nd edition
108. • Flow Properties
-It is a very important property specially for carving and
preparation of different type of (direct and indirect) wax
patterns.
- Depends on:- compositions and increases with temperature.
108
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109. • Residual stresses
- It is may be compressive or tensile in nature.
- Regardless of the method used to make a wax pattern(i.e.
softening, moulding or cooling)residual stress exists in complete
pattern.
- This patterns are stressed and strained, if the softening,
moulding or cooling is not done properly.
- E.g. -If a modeling wax sheet is slightly rolled and left, it
recovers its original shape, this is known as ”WAX MEMORY”
- If the temp. is higher , recovery to original shape takes place
faster.
109
110. • Ductility
- Increase in temperature leads to increase in ductility.
- If melting temperature is low, increase in ductility.
110
112. Corrective Impression Wax
• It is used as a wax veneer over an original impression to
contact and register the detail of the soft tissue.
• Composition:-
-Paraffin Wax
-Ceresin Wax
-Bees Wax
• Flow is 100% at 37°C.
112
113. Uses
• To make functional impression in partial dentures
• To record posterior palatal seal.
• Functional impression of obturators.
113
114. Bite Registration wax
Composition:-
Paraffin Wax
Ceresin Wax
Bees Wax
Supply:
Ushaped thin sheets which is sometime metalized or foil
laminated.
114
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Nandish-2nd edition
115. Uses:-
-To record occlusal relationship of the opposite quadrants.
-To articulate accurately certain model of opposite quadrants
FLOW:-
At 37°C it ranges from 2.5% to 22%
115
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Nandish-2nd edition
116. Procedure
• Wax is softened in warm water .
• Soft wax is than placed between the teeth.
• Patient is asked to bite.
• It is then taken out and placed in chilled water.
• The indention thus formed on the wax are used to place the
cast in position.
• It is then mounted on articulator.
116
117. Various Techniques Used In Prosthodontics Based
On Rigid Impression Materials
• Admixed technique
117
Atrophic maxillary ridge Atrophic mandibular ridge
Maxillary (zinc oxide eugenol) and mandibular
(admix) secondary impressions
Management of Compromised Ridges: A Case Report Smita Sara Manoj • Vidya Chitre • Meena ArasJ Indian Prosthodont Soc (Apr-
June 2011) 11(2):125–129
118. Neutral zone
118
• Place plaster or silicone putty index around
the model and impression.
• Remove the Neutral zone impression
from the base plate.
• Replace the index.
• Pour wax into the remaining space so that it
attached to the base plate
119. Fluid wax technique
• All procedures for regarding the location and transfer of the
marking of the vibrating lines delineated under the
conventional approach is performed.
• Impressions are made (preferably with ZoE or plaster.)
119
Winkler S. Essentials of Complete Denture prosthodontics.2nd ed.New Delhi,India.AIBTS;2000
120. • All the waxes are designed to flow at mouth temperature.
• The melted wax is painted onto the impression surface
within the outlines of the seal area.
• A little excess is added and allowed to cool to below mouth
temperature to increase its consistency and make it more
resistant to flow.
• The impression is then held in the mouth under gentle
pressure for 4-6 mins.
• The soft palate should be recorded in its most functionally
depressed position .
120
Winkler S. Essentials of Complete Denture prosthodontics.2nd ed.New Delhi,India.AIBTS;2000
121. • Maximum depression of soft palate will be recorded when the
Frankfort horizontal plane is 30° and the tongue is held firmly
against the mandibular incisor teeth.
• The wax will appear glossy if tissue contact has been made, it
will appear dull otherwise, if dull then more wax is to be added
and the procedure ah” to be repeated again.
• At no time the patient should protrude the tongue beyond the
approximated position of incisal edges
• This will foreshorten the posterior border of the denture. Any
excess wax is cut off with a sharp scalpel.
121
Winkler S. Essentials of Complete Denture prosthodontics.2nd ed.New Delhi,India.AIBTS;2000
123. NISSAN JOSEPH, MARTIN ORMIANER, BARNEA, EITAN,
ASSIF, DAVID-HEAT TRANSFER OF IMPRESSION PLASTERS
TO AN IMPLANT-BONE INTERFACE
Did a study to measure heat generated at the implant-bone
interface caused by exothermic setting reaction of 2 impression
plasters.
There were 2 types of impression plaster used, Snow-White
(Kerr, Romulus, MI) and Xantano (Kulzer, Dormagen,
Germany). Temperature changes were recorded via embedded
thermocouples at the cervix and implant surface apex.
Implant Dentistry: 2006 :15(1) :83-88
124. Temperature increased less at the implant apex (1.5°–
2.1°C) than at the implant cervix (7.4°–10.5°C). A lower
temperature increase was shown with the Snow-White
compared with the Xantano.
They concluded that Snow-White impression plaster
appears to be safer to use in implant prosthodontics
compared with the Xantano because of its slower and
lower exothermic reaction at the implant-bone interface.
124
Implant Dentistry: 2006 :15(1) :83-88
125. SAMPATH KUMAR TEJO, ANIL G KUMAR, VIVEKANAND S
KATTIMANI, PRITI D DESAI, SANDEEP NALLA AND
KRISHNA CHAITANYA-A COMPARATIVE EVALUATION OF
DIMENSIONAL STABILITY OF THREE TYPES OF
INTEROCCLUSAL RECORDING MATERIALS-AN IN-VITRO
MULTI-CENTRE STUDY
Evaluated the time dependent linear dimensional stability
of three types of interocclusal recording materials.
Commercially available and ADA approved Polyether bite
registration paste (Ramitec),Poly vinyl siloxane bite
registration paste (Jetbite) and Zinc oxide eugenol (ZOE)
bite registration paste (Super bite) were used in the
study. 125
Head & Face Medicine 2012, 8:27
126. Comparatively the polyether bite registration material
showed less distortion with good dimensional stability
compared to Poly vinyl siloxane bite (Jetbite), Zinc oxide
eugenol(ZOE) bite (Super bite) at 1 hour, 24, 48, and 72
hours.
They concluded that Zinc oxide eugenol is dimensionally
more unstable when compared with polyether and
polyvinyl siloxane.
126
Head & Face Medicine 2012, 8:27
127. PADMA SINGH BHANDARI AND SUKHBIR SINGH-
DENTAL IMPRESSION COMPOUND AS AN EFFECTIVE
SPLINT FOR MAINTENANCE OF EAR ELEVATION IN
MICROTIA RECONSTRUCTION
Used dental impression compound as a splint which is hard at
room temperature, but becomes soft in minutes at a temperature
over 60°C. They conducted a retrospective analysis of 211
patients with microtia over 10 years who underwent staged
reconstruction for the same.
127
Indian J Plast Sury 2013:46(3): 518–520
128. Softened material was placed on the posterior aspect
of reconstructed ear after applying an antibiotic
cream over the grafted skin. It is moulded in to the
desired shape (wedge shape) with reconstructed
ear in desired position of projection.
The splint is applied in the second stage 2 weeks
after the elevation of reconstructed ear.
Splint was continued until 6 months post-surgery.
128
Indian J Plast Sury 2013:46(3): 518–520
129. The only minor problem, which they encountered,
was breakage of the splint due to fall. There have
been no complaints of dermatitis, loss of the graft or
necrosis of the post-auricular skin in their series.
129
Splint in place on the posterior aspect of
reconstructed ear
Splint
Indian J Plast Sury 2013:46(3): 518–520
131. SAREH HABIBZADEH , SHIMA SAFAEIAN , MARJAN
BEHRUZIBAKHSH , PARISA KAVIYANI , MOHAMADJAVAD
KHARAZIFARD -EFFECT OF STORAGE TIME AND
TEMPERATURE ON DIMENSIONAL STABILITY OF
IMPRESSIONS MADE WITH ZINC OXIDE IMPRESSION
PASTE
This study aimed to assess the effect of storage time
and temperature on dimensional stability of impressions
made with Cavex Outline zinc oxide impression paste.
131
Journal of Dentistry, Tehran University of Medical Sciences, Tehran, Iran (2016; Vol. 13, No. 3)
132. Cavex Outline impression paste was prepared according to the
manufacturer’s instructions and applied to the mold. The mold
was placed on a block and stored at 35°C and 100% humidity for
setting.
The impressions were poured with stone immediately and also
after 30, 120, 240 and 420 minutes and 24 hours. The distance
between the vertical lines on the casts was measured and
compared with that in the immediately poured cast.
132
Journal of Dentistry, Tehran University of Medical Sciences, Tehran, Iran (2016; Vol. 13, No. 3)
133. Storage in a refrigerator and at room temperature for zero
to seven hours had no significant effect on dimensional
stability of the impressions; however, 24 hours of storage
in a refrigerator or at room temperature decreased the
dimensional stability of Cavex Outline.
Significant association was found between dimensional
changes following 24 hours of storage in a refrigerator
(4°C) and at room temperature.
The optimal pouring time of Cavex Outline impressions
with stone is between zero to seven hours, and 24 hours
of storage significantly decreases the dimensional
stability.
133
Journal of Dentistry, Tehran University of Medical Sciences, Tehran, Iran (2016; Vol. 13, No. 3)
134. SMITHA DANIEL, ANGLEENA Y. DANIEL, NIRMAL
KURIAN-A MODIFIED PHYSIOLOGIC
IMPRESSION TECHNIQUE FOR ATROPHIC
MANDIBULAR RIDGES
Restoration of comfort, esthetics and masticatory
function in severely resorbed atrophic ridges is
challenging to the clinician.
Extreme resorption of the maxillary and mandibular
denture bearing areas results in unstable and
nonretentive dentures with associated pain and
discomfort.
134
CHRISMED Journal of Health and Research : 2017: 205(4)
135. This article attempts to present a modified
physiologic impression technique using
contemporary materials and suitable spacer design
for atrophic mandible
135
CHRISMED Journal of Health and Research : 2017: 205(4)
136. 136
Case 1 - Pretreatment photograph showing
mandibular atrophy. The patient had a chief
complaint of loose lower dentures and has
been a
denture wearer for the past 15 years
Case 2 - Pretreatment photograph showing
thin resorbed mandibular ridge. The patient
was a denture wearer for the past 12 years
CHRISMED Journal of Health and Research : 2017: 205(4)
137. CA
137
CHRISMED Journal of Health and Research : 2017: 205(4)
Case1 - Preliminary Impression
Case 2 - Preliminary impression
138. 138
CHRISMED Journal of Health and Research : 2017: 205(4)
Case 1 - Incremental impression made
with low fusing impression compound
Case 2 - Incremental impression
made with low fusing impression
compound
139. 139
CHRISMED Journal of Health and Research : 2017: 205(4)
Case 1- Final impression with light
body impression material
Case 2 - Final impression with light body
impression material
140. Conclusion
• As more and more advances are taking place in field of
impression materials older materials like impression
compound, plaster and waxes are loosing their place due to
there incompetence with recent materials in terms of elasticity
and surface details.
• Still impression compound is 1st choice of material as a
primary impression for beginner and mass practices.
140
141. References
∞ Science of Dental MaterialScience of Dental Materials Clinical
applications-V Shama.BT Nandish-2nd edition.
∞ Craig’s Restorative Dental Materials –John M.Power.RonaldL.Sakaguchi-
12th Edition-Elsevier
∞ Philips’Science Dental Materials-Anusavice-10th Edition-Elsevier
∞ Philips’Science Dental Materials-Anusavice-11th Edition-Elsevier
∞ Heat Transfer of Impression Plasters to an Implant-Bone Interface Implant
Dentistry:March 2006;15(1):83-88.
∞ Dental impression compound as an effective splint for maintenance of ear
elevation in microtia reconstruction; Indian J Plast Surg. 2013 Sep-Dec;
46(3): 518–520.
∞ A comparative evaluation of dimensional stability of three types of
interocclusal recording materials-an in-vitro multi-centre study; Head &
Face Medicine 2012, 8:27
141
142. ∞ CHRISMED Journal of Health and Research : 2017: 205(4)
∞ Prosthetic treatment for edentulous patients:complete dentures and
implant supported prostheses: ZARB.HOBKIRK.ECKERT.JACOB.
:Edition 13th
∞ Effect of Storage Time and Temperature on Dimensional Stability of
Impressions Made with Zinc Oxide Impression Paste;Journal of Dentistry,
Tehran University of Medical Sciences, Tehran, Iran (2016; Vol. 13, No.
3)
∞ Winkler S. Essentials of Complete Denture prosthodontics.2nd ed.New
Delhi,India.AIBTS;2000
∞ Victor E. Beresin, Frank J Schiesser. The neutral zone in complete and
partial dentures. Second edition.
∞ Glossary of Prosthodontics Terms-4th edition.
∞ Glossary of Prosthodontics Terms-9th edition
142
3parts of impression compound and 7 parts of tray compound
Technique given by Mc Cord and Tyson
It is the area in the mouth where, during function, the forces of the tongue pressing outward are neutralized by the forces of the cheeks and lips pressing inward.
Victor E. Beresin, Frank J Schiesser
A large tongue
Atrophied mandibular residual alveolar ridge.
Partial glossectomy
Motor nerve damage to the tongue
Facial palsy.
Sucking, masticating, mouth exercises (including tongue movements, blowing, protruding of the tongue, exercise movements of the lips, cheek, and tongue, facial expression, opening and closing), and whistling.
Microtia is a congenital deformity where the pinna (external ear) is underdeveloped
Admixed technique 3:7 parts by weight……..3 parts of type 1 and 7 parts of type 2
working time is 90sec
Water temperature is 60°C
