Diagnostic Casts
Positive replicas of the teeth 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.
Bite Registration
An impression of the occlusal relationship of opposing teeth in centric occlusion (patients normal bite)
Colloid
Gluelike 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.
Hydrocolloid
A water-based colloid used as an elastic impression material
Reversible hydrocolloid
An 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.
Irreversible hydrocolloid
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.
Agar
A powder derived from seaweed that is a major component of reversible hydrocolloid
Sol
Liquid state in which colloidal particles are suspended. By cooling or chemical reaction it can change into a gel.
Gel
A semisolid state in which colloid particles form a framework that traps liquid (e.g., jell-o)
Hysteresis
The property of a material to have two different temperatures for melting and solidifying, unlike water, which has one temperature for both.
Syneresis
A characteristic of gels to contract and squeeze out some liquid that then accumulates on the surface.
Alginate
A versatile irreversible hydrocollid impression 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.
Imbibition
The act of absorbing moisture
Surfactant
A chemical that lowers the surface tension of a substance so that it is more readily wet. Fro example, oil beads on the surface of water, but soap acts as a surfactant to allow the oil to spread over the surface.
Polysulfide
A rubber impression material that has sulfur-containing (mercaptan) functional groups.
Condensation silicone
A silicone rubber impression material that sets by linking of molecules in long chains but produces a liquid by-product by condensation.
Addition silicon
A silicone rubber impression that also sets by linking of molecules in long chains but produces no by-product. Addition silicones are commoly known as polyvinyl siloxanes and are the most popular materials for crown and bridge procedures because of their
Polyether
A rubber impression material with ether functional groups. It has high accuracy and is popular for crown and bridge procedures.
Impression compound
An impression material composed of resin and wax with fillers added to make it stronger and more stable than wax.
Impression plaster
An impression material composed of a gypsum product similar to plaster of Paris.
Zinc oxide eugenol
A hard and brittle impression material used in complete denture procedures.
A dental impression material
Allows the creation of a replica of the structures involved
Impression materials that is transformed from a sol to a gel state when set is
Alginate and agar hydrocolloids
An example of an inelastic impression material
Dental compound
The types of impression materials that are considered hydrophilic are those that
Have good surface-wetting characteristics
Hydrophobic impression materials
Need a dry field to get the best results
Alginate impression material
Can be immersed in an appropriate disinifectant for up to 30 minutes without distorting
Agar hydrocolloid
Works well in a moist field
An irreversible hydrocolloid
Cannot reverse from a gel to a sol because a chemical reaction prevents it
Polyvinyl impression materials are of the class known as
Elastomers
Polysulfide impression materials
Have excellent tear strength
What is an elastomer that will imbibe water when immersed in it and swell?
Polyethers
What material produces alcohol as a by-product of its setting reaction and is subject to distortion as it evaporates?
Condensation silicone
The following statement is TRUE about the addition silicones.
They are very dimensionally stable
The most rigid of the elastic impression materials is
Polyether
The least accurate of the elastic impression materials is
Alginate
Which elastomers do NOT need to be poured with gypsum material within a few hours after the impression is made?
Addition silicone and Polyether
Dental compound impression material can change from a solid to a soft material by heating it. Its greatest use today is for which procedure?
Border molding custom trays for denture impressions
What material is used for denture impressions, that is broken into pieces to remove it from the mouth and reassembled in the laboratory to pour the impression?
Impression plaster
Zinc oxide eugenol impression material is
Used alone in a custom acrylic resin impression tray as a wash material
Disinfecting of impressions
Must be done for all impressions