Chapter 15: Impression Materials

Question 1

Positive replicas of the teeth and surrounding oral tissues and structures produced from impressions that create a negative representation of the teeth; commonly called study models and used for diagnostic purposes and numerous chairside and laboratory procedures.

Answer 1

Diagnostic casts

Question 2

An impression of the dentition and surrounding tissues taken as a precursor to other treatment; often used to make casts (models) of oral structures for planning, and to construct custom trays or provisional restorations.

Answer 2

Preliminary Impression

Question 3

A detailed impression of the upper and lower teeth in the patient’s normal bite relation.

Answer 3

Final Impression

Question 4

An impression of the upper and lower teeth in the patient’s normal bite relation.

Answer 4

Bite registration

Question 5

Ability of a material to maintain its size and shape over a period of time

Answer 5

Dimensional stability

Question 6

Ability of a material to adapt to and flow over the surfaces of the oral structures to record fine detail

Answer 6

Accuracy

Question 7

Ability to avoid tearing when the material is in thin sections

Answer 7

Tear resistance

Question 8

Glue-like material composed of two or more substances in which one substance does not go into solution but is suspended within another substance; it has at least two phases; a liquid phase called a sol and a semisolid phase called a gel

Answer 8

Colloid

Question 9

A water-based colloid used as an elastic impression material

Answer 9

Hydrocolloid

Question 10

An agar impression material that can be heated to change a gel into a fluid sol state that can flow around the teeth, and then cooled to gel again to make an impression of the shapes of the oral structures

Answer 10

Reversible hydrocolloid

Question 11

An alginate impression material that is mixed to a sol state and as it sets converts to a gel by a chemical reaction that irreversibly changes its nature.

Answer 11

Irreversible hydrocolloid

Question 12

A powder derived from seaweed that is a major component of reversible hydrocolloid

Answer 12

Agar

Question 13

Liquid state in which colloidal particles are suspended; by cooling or a chemical reaction, it can change into a gel.

Answer 13

Sol

Question 14

A semisolid state in which colloid particles for a framework that traps liquid (e.g. Jell-O)

Answer 14

Gel

Question 15

A versatile irreversible hydrocolloid that is the most used impression material in the dental office; it lacks the accuracy and fine surface detail needed for impressions for crown and bridge procedures

Answer 15

Alginate

Question 16

A characteristic of gels when left standing to contract and squeeze out some liquid that then accumulates on the surface

Answer 16

Syneresis

Question 17

Highly accurate elastic impression materials that have qualities similar to rubber; they are used extensively in indirect restorative techniques, such as crown and bridge procedures

Answer 17

Elastomers

Question 18

The act of absorbing moisure

Answer 18

Imbibition

Question 19

A chemical that lowers the surface tension of a substance so that it is more readily wetted; for example, oil beads on the surface of water, but soap acts as______ to allow the oil to spread over the surface.

Answer 19

Surfactant

Question 20

An elastic impression material that has sulfur-containing (mercaptan) functional groups; it has also been referred to as rubber base impression material

Answer 20

Polysulfide

Question 21

A silicone rubber impression material that sets by linking molecules in long chains but produces a liquid by-product by condensation

Answer 21

Condensation silicone

Question 22

A silicone rubber impression that also sets by linking molecules in long chains but produces no by-product; the most commonly used addition silicones are the polyvinyl siloxanes

Answer 22

Addition Silicone

Question 23

Very accurate addition silicone elastomer impression material; it is used extensively for crown and bridge procedures because of its accuracy, dimensional stability, and ease of use

Answer 23

Polyvinyl Siloxane (PVS)

Question 24

A rubber impression material with ether functional groups; it has high accuracy and is popular for crown and bridge procedures.

Answer 24

Polyether

Question 25

A chemical used in tissue management during gingival retraction to control bleeding and constrict

Answer 25

Astringent

Question 26

Detailed digital images of the preparation, surrounding and opposing teeth, and tissues taken by a digital scanner for the purpose of making a restoration

Answer 26

Digital Impression