Chapter 15 and 16 Flashcards
Diagnostic casts
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
Preliminary impression
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
Final impression
a detailed impression of oral structures used to make an accurate cast from which restorations or protheses are made
Bite registration
An impression of the upper and lower teeth in the patients normal bite relation
Hydrocolloid
A water based colloid used as an elastic impresion 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, and then cooled to gel again to make an impression of the shapes of the oral structures
Agar
A powder derived from seaweed that is a major component of reversible hydrocolloid
Alginate
A versitile 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
Syneresis
A characteristic of gels when let standing to contract and squeeze out some liquid that then accumulates on the surface
Imbibtion
act of absorbing moisture
Surfactant
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 a surfactant to allow the oil to spread over the surface
Polysulfide
An elastic impression material that has sulfur containing (mercaptan) functional groups; it has also been referred to as rubber base impression material
Polyvinyl Siloxane (PVS)
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
Casts
Hard replicas of hard and soft tissue of the patients oral cavity, made from gypsum products; also referred to as models
Diagnostic casts
casts generally made from dental plaster or stone and used for patient education, treatment planning, and tracking the progress of treatment, as with orthodontic models; these casts are also known as study models
Working casts
casts generally made from one of the dental stones that are strong enough to resist the stresses of fabricating an indirect restoration or prothesis; these casts are also known as master casts or working models
Dies
replicas of the prepared teeth that are generally removable from the working casts
Model plaster
the weakest, most porous form of gypsum product used in dentistry
Dental stone
a stronger, less porous form of gypsum product used in dentistry
Die stone
the densest form of gypsum product used in dentistry
Pouring
pouring the cast refers to the process of vibrating the flowable gypsum product into an impression; this process must produce a cast that is an exact replica of the impression
Trimming
the process of removing excess hardened gypsum from the cast for ease in working with the cast and appearance and presentation
Melting range
a range of melting points of the individual components of wax
Flow
the movement of wax as it approaches the melting range
