Question

Arrange the following elastomeric impression materials in decreasing order of their linear contraction:

• A. CS>PS>PE>AS
• B. AS>PE>PS>CS
• C. PE>CS>AS>PS
• D. PS>AS>PE>CS

Hint:

Addition silicone has the least shrinkage because it produces no volatile by-products during polymerization.

Answer 1

The Correct Option is A

Step 1: Understanding Linear Contraction in Elastomers.
Linear contraction refers to dimensional shrinkage that occurs after polymerizationElastomeric impression materials show varying degrees of shrinkage depending on their chemical reaction and by-products formed during setting
Step 2: Comparison Based on Setting Reaction.
Condensation Silicone (CS): Shows the highest contraction because it releases alcohol as a by-productAlcohol evaporation leads to greater shrinkage
Polysulfide (PS): Also produces water as a by-product, resulting in noticeable dimensional change but less than condensation silicone
Polyether (PE): Exhibits moderate shrinkage and better dimensional stability compared to CS and PS
Addition Silicone (AS): Shows the least linear contraction because it undergoes addition polymerization without by-product formationHence, it has excellent dimensional stability
Step 3: Decreasing Order of Contraction.
From highest to lowest linear contraction:
Condensation Silicone>Polysulfide>Polyether>Addition Silicone
Step 4: Conclusion.
Therefore, the correct decreasing order is CS>PS>PE>AS