Impression materials are used to make replicas of oral structures.

All impression materials must be in a plastic or fluid state while the replica is being made.



A model or cast material (e.g,. plaster of Paris or high-strength stone) is poured into the impression and, upon setting, produces a positive impression of the tissues of interest.

Usually, the impression material is carried to the mouth in an unset (plastic) condition in a tray and applied to the area under treatment. When the impression material has set, it is removed from the mouth with the tray.

The cast is made by filling the impression with dental stone or other model material.

The accuracy, detail, and quality of this final replica are of the greatest importance.

Sometimes, impression materials are used to duplicate a cast or model that has been formed., when more than one positive reproduction is required.

Such impression materials are referred to as duplicating materials.