A dental impression is a negative imprint of hard (teeth) and soft tissues in the mouth from which a positive reproduction (or cast) can be formed.
They are made by using a container which is designed to roughly fit over the dental arches ("trays").
Impression materials are designed to be liquid or semi-solid when first mixed and placed in the tray, and then quickly set to a solid (usually a few minutes depending upon the material), leaving an imprint of the structures in the mouth.
► See also: 8 Keys to a Beautiful Alginate Impression
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