Which impression material is known for changing from gel to liquid when heated and back to gel when cooled?

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Multiple Choice

Which impression material is known for changing from gel to liquid when heated and back to gel when cooled?

Thermoreversible gelation is being tested here. The material that changes from gel to liquid when heated and back to gel when cooled is agar-based reversible hydrocolloid. Its state depends on temperature: heat it and it liquefies, cool it and it re-gels. This unique property allows it to be liquefied for easy handling and then set again for accurate impressions or multiple pours. Other materials don’t share this behavior. Alginate, while also a hydrocolloid, is irreversible—once it has set into a gel, heating won’t return it to a liquid. Zinc phosphate is a cement, not a hydrocolloid impression material, and it doesn’t undergo a reversible gel–liquid transition. Polyvinyl siloxane is an elastomer that cures by chemical polymerization and does not liquefy with heating.

Thermoreversible gelation is being tested here. The material that changes from gel to liquid when heated and back to gel when cooled is agar-based reversible hydrocolloid. Its state depends on temperature: heat it and it liquefies, cool it and it re-gels. This unique property allows it to be liquefied for easy handling and then set again for accurate impressions or multiple pours.

Other materials don’t share this behavior. Alginate, while also a hydrocolloid, is irreversible—once it has set into a gel, heating won’t return it to a liquid. Zinc phosphate is a cement, not a hydrocolloid impression material, and it doesn’t undergo a reversible gel–liquid transition. Polyvinyl siloxane is an elastomer that cures by chemical polymerization and does not liquefy with heating.

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