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IMPRESSION COMPOUND
Dr. Anjana Maharjan
CONTENT Introduction
 Composition
 Type
 Properties
 Dimensional Stability
 Precaution
 Advantage/Disadvantage
INTRODUCTION
 Impression compounds are thermoplastic
materials softened to their working
consistency by immersion in hot ...
COMPOSITION
Ingredients Parts
Rosin 30
Copal resin 30
Carnauba wax 10
Stearic acid 5
Talc 25 (75)
Coloring agent Appropria...
TYPE
1. Lower Fusing - Impression Compound
2. Higher Fusing – Tray Compound
TYPE I
 Available as sheets, sticks, cylinders and
cones
 Should flow readily at just above mouth
temperature
 Should b...
TYPE I
Low Fusing - Green stick compound- 54 C
Medium Fusing – Impression compound -
TYPE I – SHEETS
 Recording Impression of edentulous ridge
 Manipulation:
 Compound softened in water bath kneaded
with ...
Conti..
 Gauze is placed at bottom of water bath to
prevent adherence
 Soften by heat, inserted in an impression tray
an...
TYPE I - STICKS
 Soften with flame
 Skill and experience is required
 Material is tempered in a water bath before
placi...
STICKS - COPPER RING
TECHNIQUE
 Recording a single
tooth preparation
using stick
 Hollow open ended
copper tube used as
...
Conti…
 A separate locating impression is also
recorded of the prepared tooth
 The die is inserted into this impression ...
STICKS - MANIPULATION
 For adequate border seal for retention of CD
 Trimming special tray until it is short of lines
of...
Conti..
 Care should be taken not to burn patient
 Used in distal extent of palatal coverage of
upper denture for border...
TYPE II
 Also k/a tray compound
 Making impression tray
 Not distorted at mouth temperature
 Used for corrective wash ...
PROPERTIES
Glass transition temperature
 Temperature at which material losses its
hardness i.e. 39◦C or brittleness
 At ...
PROPERTIES
Fusion Temperature:
 Indicates definite reduction in plasticity of
materials during cooling
 Heating at appro...
PROPERTIES
Fusion Temperature:
 Once the impression tray is seated, it should
be held gently(passively) in position until...
THERMAL PROPERTIES
 Coefficient of thermal expansion 0.3% is
acceptable
 conductivity is very low thus need extended
tim...
THERMAL PROPERTIES
 Cold water can be sprayed on the tray while it
is in the mouth until the compound is
thoroughly harde...
SOFTENING AND FLOW
 Soften at point just above mouth temperature
and exhibit adequate flow to adapt closely to
tissue and...
SOFTENING AND FLOW
VISCOSITY
 Most viscous of impression material i.e.
4000(pas)
 70 times greater than impression plaster
 100 times grea...
VISCOSITY
Significance
1. Limits degree of fine detail which can be
recorded in impression
2. Characterizes compound as a ...
VISCOSITY
Advantage
1. Recording impression of some edentulous
patient for recording full depth of sulcus so
that a dentur...
DIMENSIONAL STABILITY
 Relaxation can occur in short time period with
increased temperature
 Relaxation causes warpage o...
DIMENSIONAL STABILITY
 To reduce distortion one has to allow the
thorough cooling of impression before
removal from mouth...
PRECAUTIONS
 Prolong heating /immersion in water bath
cause compound to be brittle and grainy due
to leaching out of low ...
PRECAUTIONS
 Incorporation of water acts as plasticizer
 Wet kneading causes incorporation of water in
compound causes i...
ADVANTAGES
 Cheap and reusable
 Does not produce irritation to patient
 Can be remodify and resoften again till the
acc...
DISADVANTAGES
 Difficult to record details because of high
viscosity
 Mucocompressive
 Distortion due to poor dimension...
DISINFECTION
In 2% alkaline glutaraldehyde solution
impression is immersed for 10 minutes ,
rinsed and poured
ADA specification 3 for impression compound
1. Requires to be homogenous
2. Should be smooth and glossy in appearance afte...
REFERENCES
 Applied Dental Materials - 9th edition-Jhon
F.McCabe and Angus W.G.Walls
 Restorative Dental Material – Crai...
Thank you
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Impression compound

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Impression compound

  1. 1. IMPRESSION COMPOUND Dr. Anjana Maharjan
  2. 2. CONTENT Introduction  Composition  Type  Properties  Dimensional Stability  Precaution  Advantage/Disadvantage
  3. 3. INTRODUCTION  Impression compounds are thermoplastic materials softened to their working consistency by immersion in hot water or by warming over the flame.  Rigid after setting and has poor elastic properties
  4. 4. COMPOSITION Ingredients Parts Rosin 30 Copal resin 30 Carnauba wax 10 Stearic acid 5 Talc 25 (75) Coloring agent Appropriate Amount
  5. 5. TYPE 1. Lower Fusing - Impression Compound 2. Higher Fusing – Tray Compound
  6. 6. TYPE I  Available as sheets, sticks, cylinders and cones  Should flow readily at just above mouth temperature  Should be capable of recording sharp grooves 0.2-4 mm wide into the surface of metal test block  Most viscous of impression material i.e 4000 (pas) thus characterized as mucocompressive
  7. 7. TYPE I Low Fusing - Green stick compound- 54 C Medium Fusing – Impression compound -
  8. 8. TYPE I – SHEETS  Recording Impression of edentulous ridge  Manipulation:  Compound softened in water bath kneaded with finger to improve qualities  Temperature of water bath 55-60◦C is ideal for 4-5 mins to ensure complete softening
  9. 9. Conti..  Gauze is placed at bottom of water bath to prevent adherence  Soften by heat, inserted in an impression tray and placed against tissue before it cools to a rigid mass
  10. 10. TYPE I - STICKS  Soften with flame  Skill and experience is required  Material is tempered in a water bath before placing in the patient’s mouth  Used to refine /modify peripheral extent of special tray for CD or edentulous region of RPD  Used for securing rubberdam retainer and occlusal registration plate  Recording single crown preparation
  11. 11. STICKS - COPPER RING TECHNIQUE  Recording a single tooth preparation using stick  Hollow open ended copper tube used as a tray
  12. 12. Conti…  A separate locating impression is also recorded of the prepared tooth  The die is inserted into this impression and a stone working model is made by pouring a stone  This technique is superseded by the use of rubber base  Still used where moisture control is a problem
  13. 13. STICKS - MANIPULATION  For adequate border seal for retention of CD  Trimming special tray until it is short of lines of movement of mucosa  Tray periphery is coated with soften greenstick and tray replaced in mouth  Cheeks are manipulated to stimulate functional movement to produce dynamically generated shape
  14. 14. Conti..  Care should be taken not to burn patient  Used in distal extent of palatal coverage of upper denture for border seal
  15. 15. TYPE II  Also k/a tray compound  Making impression tray  Not distorted at mouth temperature  Used for corrective wash impression by adapting soften compound on study model and border of denture area trimmed  Tray compound lacks dimensional stability and strength  Thus replaced by acrylics and plastics
  16. 16. PROPERTIES Glass transition temperature  Temperature at which material losses its hardness i.e. 39◦C or brittleness  At this stage it is not plastic or soft enough for making impression  Forms a rigid mass upon cooling
  17. 17. PROPERTIES Fusion Temperature:  Indicates definite reduction in plasticity of materials during cooling  Heating at approximately 43.5◦C material soften to plastic mass that can be manipulated  Above this temperature soften material remains plastic while impression being made
  18. 18. PROPERTIES Fusion Temperature:  Once the impression tray is seated, it should be held gently(passively) in position until the impression cools below the fusion temperature  Impression should not be removed until it reaches oral temperature
  19. 19. THERMAL PROPERTIES  Coefficient of thermal expansion 0.3% is acceptable  conductivity is very low thus need extended time to achieve thorough heating and cooling  The materials should be uniformly soft at the time it is placed on the tray and thoroughly cooled in the tray before the impression is withdrawn from the mouth
  20. 20. THERMAL PROPERTIES  Cold water can be sprayed on the tray while it is in the mouth until the compound is thoroughly hardened prior to removal of impression tray from mouth  Low thermal conductivity influences cooling Outerside cools rapidly and innerside remains soft thus adequate time is required for cooling
  21. 21. SOFTENING AND FLOW  Soften at point just above mouth temperature and exhibit adequate flow to adapt closely to tissue and register details  Hardens at mouth temperature and exhibit minimum flow to reduce danger of distortion on removal
  22. 22. SOFTENING AND FLOW
  23. 23. VISCOSITY  Most viscous of impression material i.e. 4000(pas)  70 times greater than impression plaster  100 times greater than light body elastomers
  24. 24. VISCOSITY Significance 1. Limits degree of fine detail which can be recorded in impression 2. Characterizes compound as a mucocompressive impression material
  25. 25. VISCOSITY Advantage 1. Recording impression of some edentulous patient for recording full depth of sulcus so that a denture with adequate retention can be designed 2. Able to displace the lingual and buccal soft tissue sufficiently
  26. 26. DIMENSIONAL STABILITY  Relaxation can occur in short time period with increased temperature  Relaxation causes warpage or distortion of impression
  27. 27. DIMENSIONAL STABILITY  To reduce distortion one has to allow the thorough cooling of impression before removal from mouth  Construct cast or die as soon as possible (within 1 hr)
  28. 28. PRECAUTIONS  Prolong heating /immersion in water bath cause compound to be brittle and grainy due to leaching out of low molecular weight ingredients e.g. stearic acid  Compound should not be allowed to boil or inginite so that the constituents are volatized while using flame
  29. 29. PRECAUTIONS  Incorporation of water acts as plasticizer  Wet kneading causes incorporation of water in compound causes increased flow at mouth temperature causing distortion on removal  Reheating also causes increased flow
  30. 30. ADVANTAGES  Cheap and reusable  Does not produce irritation to patient  Can be remodify and resoften again till the accurate impression is obtain  Compatible with die and model materials  Easily electroplated to form accurate and abrasion resistant dies
  31. 31. DISADVANTAGES  Difficult to record details because of high viscosity  Mucocompressive  Distortion due to poor dimensional stability  Difficult to remove from severe undercuts  Does not have pleasant taste
  32. 32. DISINFECTION In 2% alkaline glutaraldehyde solution impression is immersed for 10 minutes , rinsed and poured
  33. 33. ADA specification 3 for impression compound 1. Requires to be homogenous 2. Should be smooth and glossy in appearance after passed through flame 3. Must be firm and smooth while trimming with sharp knife at room temperature 4. Manufactures must indicate:  Method of softening  Working temperature  Data/curve showing shrinkage from 40-20◦C
  34. 34. REFERENCES  Applied Dental Materials - 9th edition-Jhon F.McCabe and Angus W.G.Walls  Restorative Dental Material – Craige  Phillips’ Science of Dental Materials 11th edition - Knneth J Anusavice  Dental Material Science, Mannippalli  Dental Materials and Their Selection, 3rd edition, William J O’Brein
  35. 35. Thank you

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