Polysulfide Impression Materials

Permlastic is a polysulfide, condensation-cured, elastomeric impression material in three viscosities

Polysulfide impression materials are flexible but do not have the major changes in dimensions during storage like agar and alginate. Furthermore, the polysulfide impression is much stronger and more resistant to tearing than agar or alginate. It can be electroformed and therefore metal dies or models, in addition to gypsum models, can be prepared. 

Can Alginate Be Used As Muco-Compressive Impression Material?

The alginate impression material cannot be used as muco-compressive material. This material does not have consistency enough to apply pressure on mucosa. Therefore, muco-compressive impressions cannot be taken by alginate.

The muco-compressive impression can only be taken by impression compound or heavy duty (putty) rubber base impression materials as they both have thick consistency.