A simplified explanation of mucostatic and mucocompressive and selective pressure impression technique. difference between rigid and non rigid with the advantages and disadvantages types of materials, manipulation techniques, uses had described in detail. based on exam point of view

1. IMPRESSION MATERIALS
PART - 2
Dr. shiva sai

2. Based on
mechanical
properties
Elastic
Nonelastic or
rigid
soft tissue
Mucostatic
Mucocompressive
Selective
pressure
nature of
hardening
physical change
chemical change
Viscosity
High viscosity
Medium viscosity
Low viscosity
Dispensing
system
Cakes, cylinders,
sticks, and cones
Powder
Two-paste system
Three-paste
system
Single paste
system
clinical
applications
Preliminary
Secondary

3. Mucocompressive

4. Mucostatic

5. Selective pressure

6. Classification of impression materials
setting
mechanism
Inelasticity elasticity

7. PLASTICIZERS
• It reduces strength and
hardness.
• It reduces glass transition
temperature of a polymer.
• It increases polymer flexibility
and flow characteristics.
PLASTICIZER
External Plasticizers
physically blended with
the polymer and do not
enter the polymerization
reaction but are
distributed throughout
the polymerized mass.
Internal Plasticizers
plasticizer does not leach
out and the material
remains more flexible

8. FILLERAND
PLASTICIZER
Filler = increases
strength and hardness
Filler = ground nuts
Plasticizer = jaggery
filler α 1/plasticizer

9. Rigid impression materials

10. Impression Compound
ADA Specification Number – 3
Alternative Names
• • Dental compound
• • Model compound
• • Model plastic

12. Impression compound
Type I
Low fusing
Impression
compound
Green stick
compound
Type II
high fusing
Tray
compound

13. Setting Reaction

14. Properties
•Biological Properties
•Rheological Properties
•Thermal Properties
•Mechanical Properties

15. Manipulation
Softening
• 55°C–60°C
Kneading
• to obtain uniform plasticity
Loading
• Placing in impression tray
Tempering
• Immersing in hot and cold water
Making impression
• cools to mouth temperature

16. Softening
• 55°C–60°C
Kneading
• to obtain uniform plasticity
Loading
• Placing in impression tray
Tempering
• Immersing in hot and cold water
Making impression
• cools to mouth temperature

17. Advantages
• compressing soft tissues.
• close peripheral seal.
• Can be used in combination with other
materials.
• added and readopted.
• Relatively cheap.
Disadvantages
• Distorts easily and should not be used
when undercuts exist.
• Does not reproduce fine surface detail.
• Can only give an accurate impression
• unhygienic since it cannot be sterilised
• large COTE and low thermal
conductivity

18. Uses
• Used for recording preliminary
impressions of edentulous arches
for the construction of special
trays

19. Green Stick Compound
•ADA - 3
•The composition of green stick compound is
almost similar to that of impression compound
with more plasticizers. It is softened by waving
over a gas flame and kneaded (dry kneading).

21. Copper RingTechnique orTube ImpressionTechnique

22. Uses
• It is used for border extensions of special trays (border
molding technique).
•To obtain an impression of single tooth preparations
using copper band.
• Peripheral seal material

23. Tray Compound
• ADA-3
• They are similar in composition and working
qualities to the impression compound except that
the temperature at which they soften, i.e. higher
(70° C) and the property of flow at mouth
temperature is minimal (less than 2%).

24. USES
• used to prepare custom made preliminary impression (special
tray) that will later hold a second impression material, which will
record final impression (secondary impression).
• NOTE:-
• Tray compounds lack strength and dimensional stability; hence
they have been replaced to a large extent by trays made from
self-cure acrylic resins.

25. Zinc Oxide Eugenol Impression Paste
• ADA Specification Number: 16
Types
Type I – Hard Type II – Soft

26. Dispensing
• Usually supplied as two pastes in
collapsible metal tubes .Tube-1 is
base (white in color) and tube-2 is
reactor (red in color).They are also
available in powder (ZnO) and liquid
(Eugenol) system

27. COMPOSITION

29. Setting reaction

30. Autocatalyzation

31. • On mixing the two pastes, a reaction between zinc and eugenol
begins.The basis of the reaction is that the phenolic – OH groups
of eugenol acts as a weak acid and undergoes an acid-base
reaction with ZnO to form a salt, “zinc eugenolate”.
• it can be seen that ionic salt bonds are formed between zinc and
phenolic oxygen of each molecule of eugenol.Two further
coordination bonds formed by donation of a pair of electrons
form methoxyoxygen to zinc.
• Water is needed to initiate the reaction and it is also a byproduct
of the reaction.This type of reaction is often called “auto
catalyzation”.

32. Acid - base reaction

33. Setting Time
Initial Setting Time
Type – 1
3-6 min
Type – 2
3-6 min
Final Setting Time
Type – 1
10 min
Type – 2
15 min

34. Kreb’s Penetrometer

35. Factors affecting setting time

36. Advantages
1.Accurate & stable dimensionally.
2.They adhere well to dried surfaces
of compound, resin and shellac bases
3.Inexpensive
4.Easy to manipulate
5.No requirement of separating
medium
Disadvantages
1.It cannot be used when a undercut
exists.
2.Requires special tray
3.unpleasant (may cause burning
sensation or irritation to the oral tissues).
4.Instruments are difficult to clean.

37. secondary or corrective wash
impressions of edentulous
arches.
Temporary relining material
and remodeling material.
Uses

38. Modifications
• Surgical Paste
• Bite Registration Paste
• Noneugenol Pastes
• zinc oxide is reacted with
carboxylic acid (Orthoethoxy
benzoic acid)

39. Thank you
Drshivasai

40. Scan for PPT

41. MIND MAPPING

42. Rigid impression materials
Impression
compound
Green stick Zoe
• Ada specification no
• Filler
• plasticizer
• Dispensing
• composition
• Manipulation
• Factors effecting
setting time
• Properties
• Classification
• Chemical reaction
• Advantages
• Disadvantages
• Uses
• modifications