Elastomeric impression materials Flashcards
What is the working time?
-Beings when mixing is started and ends immediately before elastic properties develop
What is set time?
-The time from the beginning of mixing until the impression can be removed from the mouth with no distortion
What does increase in temperature do to the setting time?
-Increase
What is the lack of dimensional change during setting, and shortly after removal from the mouth known as?
-Dimensional accuracy
What is the lack of dimensional change over time known as?
-Dimensional stability
How is accuracy maximized from impressions?
-Pour up model soon after removal from the mouth
If an impression material has a higher elastic limit what should that exhibit?
-Less permanent deformation
What are the two components of elastomers?
- Catalyst paste
- Base paste
What is a byproduct of the polymerization reaction of a polysulfide rubber base?
-Water
What are the advantages of polysulfides?
- Excellent tear strength
- Relatively inexpensive
- Long working time
What is a byproduct of the condensation setting reaction of condensation silicones?
-Ethyl alcohol
What is the most elastomeric impression material?
-Polyether
What is the stiffest material of elastomers?
-Polyether
What is the most hydrophillic of all elastomers?
-Polyether
What is a byproduct of polymerization of PVS?
-H2 gas
