Question

A clinician observes that the addition silicone impression material is not setting properly. Upon inquiry, it is found that the assistant handled the material while wearing latex gloves. Which of the following statements is true regarding this situation?

• A. Hydroxyl ions which are released retard the reaction
• B. Sulfur released from gloves acts as poison to platinum, slowing the reaction
• C. Water powder ratio is incorrect
• D. Alcohol is released which changes the setting time

Hint:

Never handle addition silicone (PVS) with latex glovesSulfur inhibits the platinum catalyst and prevents proper setting.

Answer 1

The Correct Option is B

Step 1: Understanding Addition Silicone Setting Reaction.
Addition silicone (polyvinyl siloxane) sets by an addition polymerization reactionThis reaction is catalyzed by a platinum compoundThe polymerization occurs without formation of by-products, which gives it excellent dimensional stability
Step 2: Effect of Latex Gloves.
Latex gloves contain sulfur-containing compounds used during vulcanizationThese sulfur compounds can contaminate the impression materialWhen addition silicone comes in contact with sulfur, the platinum catalyst becomes poisoned (inactivated)
Step 3: Mechanism of Inhibition.
Sulfur compounds interfere with the platinum catalyst and inhibit the polymerization reactionAs a result, the material may show delayed setting or complete failure to set properly
Step 4: Evaluation of Options.
(A) Hydroxyl ions which are released retard the reaction: IncorrectAddition silicone setting is not inhibited by hydroxyl ions
(B) Sulfur released from gloves acts as poison to platinum, slowing the reaction: CorrectThis explains the inhibition of setting
(C) Water powder ratio is incorrect: Not applicableAddition silicone does not use water-powder mixing
(D) Alcohol is released which changes the setting time: Alcohol is released in condensation silicone, not in addition silicone
Step 5: Conclusion.
Therefore, sulfur from latex gloves poisons the platinum catalyst, leading to improper setting of addition silicone impression material