ELASTOMERIC IMPRESSION MATERIAL-ADDITION SILICONE,POLYETHER

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 ELASTOMERIC IMPRESSION MATERIAL

 PART 2


ADDITION SILICONE:

AVAILABLE AS :

1)LIGHT

2)MEDIUM

3)HEAVY

4)PUTTY

VISCOSITIES:


  1. PASTE: 2 equal size collapsible tube
  2. Cartridge:use with gun
  3. Putty jar
Base paste :
1)Poly methyl hydrogen siloxane
2)Other siloxane pre-polymer
3)Hybrid silicone
4)Filler

CATALYST PASTE :
1)Polydimethylsiloxane
2)Platinum salt activator
3)Palladium
4)Retarder 
5)Filler 

SETTING REACTION:
  • Addition reaction
  • No by product 
  • Cross linkage between vinyl terminated silicone with silane terminated silicon 
  • 2nd reaction:
  • Moisture +residual hydride
  • Hydrogen gas is formed 
  • Addition noble metal (platinum or palladium )to component that act as hydrogen absorber
HYDROPHILIC SILICONE :
  • Addition of surfactant 
  • Advantage :
  1. Decreases air bubble in gypsum ,
  2. Better wetting of soft tissue
  • Disadvantage:
  • Difficult to electroplate 
Character:
  • No by product 
  • More dimensional stable
  • Addition of surfactant turn to hydrophilic 
ADVANTAGE:
  • Clean,pleasant
  • easily seen margin
  • elasticity
  • pour repeatedly
DISADVANTAGE:
  • Low tear strength
  • High cost
  • Putty and wash separate 
POLYETHER
Available as :
1)light 
2)medium
3)heavy
Viscosities:
  • Paste :Unequal sized collapsible 
  • Base:Larger 
  • Catalyst :Small
BASE PASTE :
  • Low molecular weight polyether
  • Filler 
  • Plasticizer
CATALYST PASTE :
1)Aromatic sulfonate intiator
2)Filler
3)Plasticizer 
  • Addition polymerisation
  • polyether +sulfonic ester = polyether rubber
CHARACTER:
  • So stiff-set
  • Hydrophilic
  • Can not be electroplated
ADVANTAGE:
  • Fast setting
  • Good stability
  • Delay poor
DISADVANTAGE :
  • Stiff
  • Bitter taste
  • Absorb water
  • High cost 



AIM OF THIS POST :

Today we started with how an  addition silicone is available ,its characters,setting reaction,advantage,disadvantage then we moved on into polyether is constituents,advantage and finally disadvantages .hope you found this post useful if you like this post then do let me know in the comment section below as this would be helpful to create more such content. Do check out Previous post on 

ELASTOMERIC IMPRESSION PART 1 to understand better .


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