Chapter 14

Question 1

Definition of diagnostic casts

Answer 1

positive replicas of the teeth produced from impressions that create a negative representation of the teeth

Question 2

Definition of bite registration

Answer 2

impression of the occlusal relationship of opposing teeth in the centric occlusion

Question 3

Definition of colloid

Answer 3

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, liquid phase called sol and semisolid called gel

Question 4

Definition of hydrocolloid

Answer 4

water-based colloid used as an elastic impression material

Question 5

Definition of reversible hydrocolloid

Answer 5

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

Question 6

Definition of irreversible hydrocolloid

Answer 6

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

Question 7

Definition of agar

Answer 7

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

Question 8

Definition of sol

Answer 8

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

Question 9

Definition of gel

Answer 9

semisolid state in which colloidal particles form a framework that traps liquid

Question 10

Definition of hysteresis

Answer 10

property of a material to have two different temperatures for melting and solidifying, unlike water, it has one temperature for both

Question 11

Definition of syneresis

Answer 11

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

Question 12

Definition of alginate

Answer 12

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

Question 13

Definition of elastomers

Answer 13

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

Question 14

Definition of imbibition

Answer 14

act of absorbing moisture

Question 15

Definition of surfactant

Answer 15

chemical that lowers the surface tension of a substance so that it is more readily wet

Question 16

Definition of polysulfide

Answer 16

elastic impression material that sulfur-containing functional groups

Question 17

Definition of condensation silicone

Answer 17

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

Question 18

Definition of addition silicone

Answer 18

rubber impression that also sets by linking molecules in long chains but proceeds no by-product

Question 19

Definition of polyvinyl siloxane

Answer 19

accurate addition silicone elastomer impression material; used extensively for crown and bridge procedures

Question 20

Definition of polyether

Answer 20

rubber impression material with ether functional groups

Question 21

Definition of impression compound

Answer 21

impression material composed of resin and wax with fillers added to make it stronger and more stable than wax

Question 22

Definition of impression plaster

Answer 22

impression material composed of gypsum product similar to plaster of Paris

Question 23

Definition of zinc oxide eugenol

Answer 23

hard and brittle impression material used in complete denture procedures