Dental The impression material that is mainly composed of sodium or potassium salts of alginic acid is _____. A Polyether B Irreversible hydrocolloid C Polyvinyl siloxane D Polysulfide 💡 Explanation The impression material that is mainly composed of sodium or potassium salts of alginic acid is _____. ✓ Correct Answer: B. Irreversible hydrocolloid