The document discusses various impression materials used for complete dentures, detailing their definitions, classifications, compositions, and properties. Key materials include impression compounds, alginate, impression plaster, zinc oxide eugenol paste, and elastomeric materials, each with specific applications and advantages. It highlights the requirements for effective impression materials, including dimensional stability, accuracy, and bio-compatibility.

1. IMPRESSION MATERIALS USED FOR
COMPLETE DENTURE
SUBMITTED BY:
MARWAN R. JASSIM
MARWAN M. AHMED

2. DEFINITION:
 A dental impression is defined as the negative record of the
tissues of the mouth . It is used to reproduce the form of the
teeth and surrounding tissues.

3. Requirements of impression material
 Must be a semi-liquid material that will flow and adapt itself around the
structure of interest.
 It must set and harden into a solid that is rigid enough to be removed
from the mouth without becoming deformed.
 Copy details accurately
 Dimensional stability after removal from the mouth
 Appropriate working time (from the start of mix)
 Appropriate time to harden in the mouth (setting time)
 Bio-compatibility/Aesthetic, odor/taste
 Chemically compatible with material used to pour cast

4. classification
 There are many types of classification, the most common classification
used in complete denture construction is based on type of impression
and area of use
 Primary
Impression compound
Alginate
 Secondary
ZOE impression paste
Elastomers for CD
Plaster of paris

5. PRIMARY IMPRESSION
 The primary impression, taken in an edentulous stock tray, is needed to
record enough detail for a special tray to be made. The primary
impression should reproduce :
1. Sulcus depth
2. Sulcus width along the entire periphery
3. Certain anatomical landmark which indicates the correct extension of the
special tray (eg maxillary tuberosity and retromolar pads.
 It is usually taken in impression compound or impression plaster (not
suitable if undercuts present).

6. Final impression
Objectives
 To obtain an impression from which a retentive, stable and comfortable
denture base can be constructed.
 To record as accurately as possible the shape of the mucosa overlying
the alveolar ridges and hard palate together with functional depth and
width of sulci.

7. Impression compound:
 Impression compound is rigid,reversible
impression material sets by physical
change.
 It softens on heating and hardens on
cooling.
 It have a type I, type II, type III
 Supplied as sheets,sticks,cakes and cones.

8. Applications:
 Making preliminary impression of edentulous mouth.
 For individual tooth impression.
 To make a special tray.
 Border moulding.
Composition: INGREDIENTS PARTS
resin 30
Copal resin 30
Carnauba wax 10
Stearic acid 5
Talc 75

9. Properties:
 Glass transitional temperature =39 degree centigrade.
 Fusin temperature=43.5 degree centigrade.
 They are poor conductors of heat.
 Coefficient of Linear Expansion is high.
 Good dimensional stability.
 Low flow.
 Fine reproduction of detail.

10. Advantages:
 Material can be reused several times.
 Inaccurate portions can be remade without having to remake the entire
impression.
 Accuracy can be improved by flaming surface material.
Disadvantages:
 Distortion due to poor dimensional stability.
 Compress soft tissue while making impression.
 Difficult to remove if there are undercuts.
 Difficult to record details because of high viscosity.

11. ALGINATE
 Its an irreversible elastic hydrocolloid
 It is a mucous extract yielded from certain brown sea weeds
 Types
type 1 – fast setting
type 2- normal setting

12. Applications
 Used for impression making;
• when there are undercuts
• in mouth with excessive flow of saliva
• For impression to make study models and
working casts
• For making preliminary impression
• Managing Hyperplastic or Flabby Tissue
(Unsupported Movable Tissue)
• Management of Severely Resorbed
Mandibular Ridge

13. Applications
 Primary impressions of maxillary
arch with the palatal defect and the mandibular arch recorded
using Alginate impression material

14. composition
INGREDIENTS FUNCTIONS
Sodium or pottasium alginate-
15%
React with calcium ion
Calcium sulphate(reactor) -
16%
React with potassium alginate
Zinc oxide -
4%
Acts as filler
Potasium titanium flouride -
3%
Gypsum hardener
Diatomacous earth -
60%
Acts as filler
Sodium phosphate(retarder) -
2%
React with calcium sulphate
Colouring and flavouring
agents
Wintergreen, orange etc.

15. PROPERTIES OF ALGINATE
 Alginate has pleasant taste and smell
 It is highly flexible
 Good elasticity and elastic recovery
 Fine reproduction of tissue detail
 Compressive strength
– ranges from 0343-70 mpa
 Tear strength- 350-700gm/cm2
 Dimensionally stable
 Poorly adheres to the tray
 Biological properties- inhalation of
silica particles cause health hazards.

16. Properties:
 Mixing time
fast setting - 45 sec
normal setting- 60sec
 Working time –
fast setting – 1min
normal setting – 2 min

17. Advantages
 Easy to mix and manipulate
 Low cost
 Comfortable to patient
 Hygienic
 Good surface detail even in presence of saliva
 Accuracy if properly handled
 Minimum requirement of equipment
Disadvantage
 It cannot be corrected
 Poor dimension stability
 Poor tear strength
 Distortion may occur if not properly handled

18. IMPRESSION PLASTER
INDICATIONS:
• Impression plaster used to record final impression for completely
edentulous arch.
PROPERTIES
 higher water/powder ratio (approximately 0.60) than is normally used for
modelling plasters.
 The fluid mix is required to enable fine detail to be recorded in the
impression and to give the material mucostatic properties.
 Freshly mixed plaster is too fluid to be used in a stock impression tray and
is normally used in a special tray, constructed using a 1–1.5 mm spacer.
 Before casting a plaster model in a plaster impression, the impression must
be coated with a separating agent (soap), otherwise separation is
impossible.

19. IMPRESSION PLASTER
CONT.
ADVANTAGES
 It capable of recording soft tissues in the uncompressed state. Due to
fluidity
 There is a very intimate contact between the impression material and
the tissues.
 minimal dimensional change on setting,
 very accurate impression which may be difficult to remove.
DISADVANTAGES
 very dry sensation after having impressions recorded.
 not suitable for use in any undercut situations (rigid material).

20. ZINC OXIDE EUGENOL IMPRESSION
PASTE:
Applications:
 Cementing and insulating medium.
 Temporary filling.
 Root canal filling material.
 Bite registration paste.
 Impression material for
edentulous patients.
 Temporary relining material
for dentures.

21. Available as:
base paste(white in colour)
Accelerator or reactor or catalyst paste(red in colour)
Composition:
Base paste Accelerator paste
Zinc oxide-87% Eugenol-12%
Fixed vegetable oil or mineral
oil-13%
Gum-50%
Filler(silica)-20%
LANOLIN-3%
Resinous balsam-10%
Accelerator solution (calcium
chloride)-5%

22. Factors controlling setting time:
 Particle size of zinc oxide powder.
 Longer mixing time, shortens setting time.
 High atmospheric temperature and
humidity accelerate setting.
 Setting can be delayed by cooling
mixing slab, spatula or adding small
amount of retarder or oils or waxes.
Properties:
 Good consistency and flow.
 Detail reproduction.
 Rigid and having good strength.
 Good dimensional stability.

23. Advantages:
 It has enough working time to complete border moulding.
 It can be checked in mouth repeatedly without deforming.
 It registers accurate surface details.
 It is dimensionally stable.
 Does not require separating media since it does not stick to cast material.
 Minor defects can be corrected.
Disadvantages:
 Requires special tray for impression making.
 Sticky in nature and adheres to tissues.
 Burning sensation of eugenol causes tissue irritation.
 Highly inelastic in nature.

24. NON-EUGENOL PASTES
 NON-EUGENOL PASTE are developed to
overcome the burning sensation caused by
eugenol.
 Bactericides and other medicaments are also
incorporated.
 Used in eugenol irritant patients.

25. IMPRESSION WAXES
 Impression waxes are rarely used to record complete impressions but are
normally used to correct small imperfections in other impressions,
particularly those of the zinc oxide/eugenol type.
 They are thermoplastic materials which flow readily at mouth temperature
and are relatively soft even at room temperature.
 They are applied with a brush in small quantities to ‘fill in’ areas of
impressions in which insufficient material has been used or in which an
‘air blow’ or crease has caused a defect.

26. ELASTOMERIC IMPRESSION MATERIAL
Classification
• A) according to chemistry
 1) polysulfide
 2) condensation polymerizing silicones
 3) addition polymerizing silicon
 4) polyether
• B) according to viscosity
 1) light bodied(syringe consistency)
 2) medium(regular)
 3) heavy body(tray consistency)
 4) very heavy(putty consistency)


27. 1.Polysulfide elastomeric impression
material
 First elastomeric impression material to be introduced.
 Supplied as
• Base paste (white)
• Accelerator (brown/grey)
• Available in 3 viscosities:
Light bodied, Medium bodied, Heavy bodied

28. COMPOSITION
A) Base paste
 liquid polysulfide polymer – 80-85%
 inert fillers - 16-18%
B) reactor paste
 lead dioxide -60-68%
 dibutyl phthalate -30-35%
 sulphur -3%
 retarders like magnesium stearate

29. Properties
 Unpleasant order and colour
 Material is extremely viscous and sticky and exhibits pseudoplasticity
 Long setting time of 12.5min
 High tear strength
 Good flexibility
 Excellent reproduction of surface detail
 Hydrophobic- tissue should be thoroughly dried before making the
impression.

30. Clinical considerations when used
 Used with custom trays
 Allow 2mm thickness
 Use tray adhesive
 Setting time 10 min.
 Have very good tear resistance.

31. advantages
 1. Long working time.
 2. Proven accuracy
 3. High tear resistance.
 4. Inexpensive to use
 5. Less hydrophobic
 6. Longer shelf life.
Disadvantages:
 1. Must be poured with dental stone immediately.
 2. Potential for significant distortion.
 3. Odor is offensive.
 4. Messy & stains clothes.
 5. Second pour is less accurate.

32. SILICON RUBBER IMPRESSION
MATERIAL
Types
 1-condensation silicones
 2-addition silicones
 Condensation silicones;
 Also known as conventional
silicones.
 Available in three viscosities
namely light,
medium bodied and heavy.

33. 1.CONDENSATION SILICONES
 It was the first type of silicone impression material.
 Also known as conventional silicones.
Composition;
Base paste
 1-polydimethyl siloxane.
 2-colloidal silica
 Color pigments.
Accelerator
Stannous octoate

34. Properties:
 1. Setting time – 8-9 min. Mixing time – 45 sec.
 2. Excellent detail reproduction
 3. Dimensional stability – high curing shrinkage.
 4. Permanent deformation – 1-3 %
 5. Tear strength – 3000gm/cm
 6. Staffer & harder than polysulfide material.
 7. Hydrophobic
 8. Can be electroplated with silver & copper.
 9. Shelf life - 2 yrs.

35. Advantages:
 1. Adequate working & setting timer.
 2. Pleasant odor & no staining.
 3. Adequate tear strength
 4. Hetter elastic properties on removal.
 5. Less distortion on removal.
Disadvantages:
 1. Adequate accuracy if poured immediately.
 2. Poor dimensional stability.
 3. Potential for significant distortion.
 4. Putty-wash method is technique sensitive.
 5. Slightly more expensive.

36. 2.ADITION SILICONES
 Introduced after condensation silicones
 Have better properties than condensation silicones.
 Also known as poly vinyl siloxane.

37. Properties:
 1. Setting time: - 5.9 min. Mixing time - 45 sec
 2. Excellent surface detail reproduction.
 3. Highest dimensional stability
amongst elastomers
 4. Lowest curing shrinkage – 0.17 %
 5. Good tear strength – 3000gm/cm
 6. Extremely hydrophobic
 7. Low flexibility
 8. Electroplated with copper & silver.
 9. Shelf life - 1-2 yrs.

38. Advantages:
1. Short setting time
2. Adequate tear strength
3. Extremely high accuracy
4. Minimal distortion on removal
5. Dimensionally stable even after 1 week
6. If hydrophilic, good compatibility with gypsum
Disadvantages:
1. Hydrogen gas may cause dimensional change.
2. Hydrophobic & hence requires a very dry field.
3. Expensive.

39. Polyether impression materials;
 Good mechanical and compressive strength
comparing other elastomers.
 Available in three viscosities.
 Consist of base paste and catalyst.
Base Paste:
 1. Imine terminated polymer(polyether)
 2. Colloidal silica
 3. Glycol ether or phthalate
Accelerator Paste:
 1. Alkyl aromatic sulfonate
 2. Colloidal silica
 3. Plasticizers ( glycoether )

40. Properties:
1. Setting time: 8.3 min. Mixing time – 30 sec.
2. Dimensional stability is good.
3. Decreased flexibility – 3%
4. Hydrophilic
5. Activator paste can produce allergy if handled frequently.
6. Tear strength – 3000gm/cm
7. Shelf life > 2 yrs.

41. Advantages
1. Short working & setting time
2. Proven accuracy
3. Adequate tear strength
4. Hydrophilic
5. Long shelf life
6. Less distortion on removal
7. Good dimensional stability.
Disadvantages
1.Stiffness requires blocking of undercuts
2. Slightly more expensive
3. Multiple casts can’t be poured due to stiffness of the material.

42. Manipulation of Elastomers:
 Manipulation of two paste systems
 equal length of base & activator paste are taken.
 Paper pad with graduations is provided by manufacturer.
 Pastes are mixed till no streaks are present.
 Tray coated with tray adhesive. Uniform two-layer coat is applied & allowed to dry.
 The mixed material can either be taken in a syringe or loaded directly in the tray.
 Manipulation of Putty Material:
 Putty dispenser is supplied with scoops for dispensing.
 Activator may be a liquid or paste.
 Putty material is taken in a scoop & the activator is added. Usually the activator is of
different color
 It is kneaded till no streaks are present.
 Putty material is used with stock trays.