Chapter 18 Dental Laboratory Materials

Rigid impression material

are used where no teeth are present

impression plaster

gypsum product 60 cc of water to 100 grams of plaster

metallic oxide paste

two-paste system

impression compound

supplied in cakes and sticks

Plastic impression materials

are used with or without the presence of teeth

thermoplastic

material softens when heated and hardens when cooled

compound

supplied in sheets or stick form

wax

used for registration of bites or for impression of single tooth area

Elastic impression materials

are used where teeth are present and material must be flexible or removal from the oral cavity or teeth

reversible hydrocolloid

impression material that can change repeatedly from gel to solid states depending on the thermal condition of the substance

gel state

material is soft and pliable

solid state

material has "set" or is rigid enough to hold the form

irreversible hydrocolloid

are used to make impressions of preparations and for demanding or accurate reproductions

catalyst

substance that speaks up the chemical reaction

extruder gun

a device that contains two independent materials to be forced mixed and dispensed into a common tip as on material

polysulfide

impression substance available in light, regular, or heavy-bodied

viscosity

thickness or tendency to flow

silicone

first supplied as a base putty with liquid accelerator drops and termed condensation or conventional silicone type or later as a tow-paste system

polyether

supplied in regular viscosity with a thinner material

modifier

material to change conditions

vinyl polysiloxane

impression material supplied in tubes, putty, paste-to-paste system

calcination

process of preparing and handling gypsum material that determines the final classification and purpose of a gypsum product

Type l plaster - impression

used to take impression but not popular because of its weakness and replacement by better impression materials

Type ll - model

also known as plaster of paris, used mostly for impression and study models

Type lll - dental stone

white or buff colored class I stone, used for orthodontic, diagnostic, and working casts

Type IV - improved or die stone

stronger class II stone used for dental dies and casts

Type V - casting investment

gypsum-bonded material that can with-stand extreme heat

model and cast

used for a positive reproduction of the mouth and oral conditions

die

reproduction of prepared tooth

inlay wax

hard wax, blue, purple, green, or ivory colors; indirect use for inlay crown and casting patterns

baseplate wax

pink in color; soft, medium, or hard. used for denture construction, bite registration, and prosthesis construction

casting wax

available in square sheets of various thicknesses; color denote its softening point; used for construction of patterns for cast partial dentures

boxing wax

used to box or wrap around an impression prior to pouring.

occlusal bite blocks

wax blocks in arch shape; used to set in teeth to be used for denture constructions

bite wafer wax

used to check occlusion relationships; supplied in a preformed bite shape with a foil center to prevent bite through

orthodontic wax

soft, white stick of wax used in orthodontics; used to line borders of impression trays

wax round wire

supplied on reels in various gauges; used to make lingual bars, sprues, and metal framework space

utility wax

soft, adhesive wax, supplied in stick or sheet; used to mount casts and to adapt or modify impression tray edges; also called rope wax

sticky wax

hard, brittle wax stick that is melted to hold dental units together

preformed wax pontic shapes

eliminates wax buildup process; supplied in carious shapes and sized of teeth

disclosing wax

also known as pressure indicator paste; painted on an appliance

miscellaneous waxes

assorted color-coded waxes with particular fine-turning properties, such as margins, sculpturing, blocking out, and dipping

acrylics

dental polymers, known as a synthetic resins

monomer and polymer

chemical union

polymerization

also knows as curing

filler

inert substance added to the polymer to alter or modify the polymer properties

initiator

agent capable of starting polymerization process

activator

reacts with initiator to start polymerization

inhibitor

substance that prevents polymerization; maintains storage life

plasticizer

substance that that causes a softening effect

composite

polymer matrix bonded to glass particles; used for dental restorations

self-curing resins

autopolymerization materials that perform the uniting process by means of a chemical union

heat-cured resins

acrylic materials are united but need outside heat to set up; not as popular as self-cured but less likely to present bubbles or voids when processed correctly

alloy

a combination of two or more metals

binary

combination of two metals

ternary

three metals

quaternary

four metals

quinary

five different metals

tempered

hardened

annealed

softened

75% gold

resists tarnish/ corrosion, nontoxic, hypoallergenic, docile, malleable, low melting point, and smooths out well

10% silver

lessens the red cast from copper and gold, increases ducility and malleability; gives strength to the alloy

10% copper

hardens in heat and high temperature; adds flowability

3% palladium

increases hardness, whitens gold, and prevents tarnish and corrosion

2% zinc

prevents porosity of surface area, and provides smoothness

slurry

thin watery mixture

polycarboxylate

the most common luting cements are used with the dental laboratory products are zinc phosphate ZOE

bonding

force of the union of one substance with another substance

coefficient of thermal expansion

amount of form change that takes place in a dental material and tooth during heat exposure in the oral cavity

color

has three components

hue

color of object--red, green blue, and so on

chroma

strength of specified hue

value

darkness or brightness of specified hue

creep

tendency of amalgam to deform under constant applied pressure

cure process

hardening of the material through auto- (chemical) or light-activated response

ductility

ability of the material to withstand permanent deformation without fracturing under elongation stress

elasticity

ability of a material to return to its original form when stress is removed

exothermic

chemical release of heat, as in zinc phosphate cement

flow

slow bending or movement of material under its own weight

galvanization

tendency of certain metals to produce an electrical charge when in contact with each other

hardness

maximum amount of resistance before penetration or scratching can occur

hydrophilic

ability to attract and hold water; absorption of water

hydrophobia

fear of water; giving off or shedding of water

hygroscopic expansion

submersion into or the addition of, water to a material prior to initial set

initial set

period of time when material assumes shape but remains pliable

imbibition

absorption of fluid; taking on water

malleability

ability to withstand deformation without fracture while undergoing maximum compression stress

setting time

amount of time required for the material to become as hard as it will be

tensile strength

maximum amount of pulling stress required to rupture the material

thermal conductivity

capability of the material to transmit heat

thoughness

ability of the material to resist fracture

trituration

ability of the material to resist fracture

working time

period during which a material can be molded, shaped, or manipulated without any adverse effect upon the material

yield strength

maximum amount of stress a material can withstand without deformation