Prosthodontics 3: Impression Making Materials & Techniques

A set of vocabulary flashcards covering dental impression materials, their chemical compositions, properties, and techniques for complete denture fabrication.

Preliminary Impression

A negative likeness made for the purpose of diagnosis, treatment planning, or for the fabrication of a tray.

Final Impression

A negative likeness made for the purpose of fabricating a prosthesis.

Impression Plaster

A mucostatic impression material whose main component is calcium sulphate hemihydrate, which reacts with water to form calcium sulphate dihydrate.

Mucostatic Impression

An impression technique that records the oral tissues with a minimum of displacement.

Mucodisplacive Impression

An impression technique that displaces the oral tissues during seating.

Zinc Oxide Eugenol (ZOE) Impression Paste

A nonelastic impression material formed by the reaction of zinc oxide and eugenol in the presence of moisture to form zinc eugenolate, exhibiting negligible setting shrinkage of $<0.1\%$.

Dental Impression Compound

A thermoplastic nonelastic material made of waxes, thermoplastic resins, fillers, shellac, stearic acid, and gutta percha that sets via a reversible physical process.

Type I Impression Compound

A lower fusing modeling plastic supplied as cakes for primary impressions in edentulous patients or as sticks for custom tray border molding.

Type II Impression Compound

A higher fusing modeling plastic used as a tray adaptation material to support a thin layer of a second impression material.

Agar (Reversible Hydrocolloid)

An elastic impression material whose setting process (gelation) is a physical phase change between sol and gel induced by temperature changes.

Gelation

A solidification process that involves physical phase changes from sol to gel states.

Alginate (Irreversible Hydrocolloid)

An elastic impression material that sets through a chemical reaction where soluble potassium alginate reacts with calcium sulphate to form an insoluble calcium alginate gel.

Polysulfide Rubber

A two-paste elastomeric system containing lead oxide that undergoes chain lengthening and cross-linking polymerization, setting into a dark brown or gray-brown rubber.

Condensation Silicone

An elastomeric impression material based on polydimethylsiloxane that produces ethyl alcohol as a reaction by-product.

Addition Silicones (PVS)

Polyvinyl siloxanes activated by a platinum salt catalyst (such as chloroplatinic acid) that set without forming reaction by-products.

Polyether Impression Material

A two-paste elastomeric impression material characterized by an inherent hydrophilic nature and a high degree of wettability of oral tissues.

Stock Tray

A pre-fabricated tray used for primary impressions that requires at least $4\,\text{mm}$ of clearance between the tray and the residual ridge.