Chapter 19 Dental Laboratory Procedures

dental laboratory technician

trained in laboratory work through formal schooling or on the job experience

certified dental technician (CDT)

what a dental lab tech can become after passing all three examinations given by the National Board for Certification

denturist

fabricates dentures and is legalized by the state dental boards in some states

ceramists

expert in ceramics; specializes in porcelain crowns and restorations

work order

is attached to each case sent to the lab; prescription order from the practicing dentist

working days

amount of time required by the laboratory to complete the prescription

articulator

device to imitate joint action

model trimmer

grinding, motorized, abrasive disc device used to trim or remove excess gypsum on diagnostic casts in preparation for placement

gypsum mixing machine

device used for mechanical mixing of gypsum products

vibrator

small table-model appliance with a platform to hold bowls of freshly mixed gypsum

furnace

heating device with high temperature range

waxing unit

heater unit to melt and hold lab wax

waxing pens/pencils

handheld electrical heating device with various insert tips used to carve and mold wax patterns

oven

hot-air heat devices to prepare materials

bath

hot oil, or water-heat device to prepare materials

hydrocolloid conditioning machine

heating device that uses water to condition and prepare reversible hydrocolloid material for impressions

burner

heating device to externally heat an object not contained within in

vacuum formers

device used to heat acrylic sheets and vacuum pressure them to prepared form for construction of a custom impression tray

electroplating unit

electrical device used to apply alloy materials to surface object

blowtorch

heating device using compressed gas or chemical fuel to melt alloys for casting

casting machine

centrifugal spin device used to force melted alloy into an investment ring

curing unit

device used to heat-cure or complete the polymerization process of acrylics

sandblasting machine

air-abrasion machine with forced abrasive material (sand) flow to polish and clean items

lathe

electrical motor with extended rods for attachment of appliances

splash pan

receptacle with high back that is inserted under the lathe wheel ends

dust collector

suction-powered unit to remove gypsum and acrylic dust from the lab area

plating unit

machine to electroplate gold veneers, precious metals, and semi-precious metals

electric motors and handpieces

benchtop units providing selective handpiece power for lab operations

welder/solder machine

electric unit used to weld orthodontic bands or for general soldering

denture

a replacement for a body part, also known as a prosthesis

full mouth denture set

a complete replacement for the maxillary and mandibular arches; composed of two trays - the maxillary denture plate and the mandibular plate

single denture

a denture replacement for one arch, either maxillary or mandibular

immediate denture

a denture that is placed in the mouth at the time the natural teeth are surgically removed

overdenture

acrylic denture prepared to fit on the bony ridge and gingiva while attached to the remaining teeth or implant devices

denture base

pink acrylic part of the denture that fits over and covers the alveolar ridge

denture teeth

artificial teeth used in denture construction

denture flange

extension of denture over the posterior anatomy present; used to stabilize

denture post dam

suction seal of denture that extends side to side from the rear of the denture

impression tray

may be custom made or purchased commercially as plain or perforated full arch

spacer

material, usually baseplate wax, that is placed on the model or cast surface to allow a space for the impression material

stop

indents or holes cut out of the spacer in the tray to prevent the tray from being placed too deeply

adhesive

sticky liquid that is painted or sprayed on the surface of the smooth impression tray to help retain the impression material in the tray

molding

finger shaping of the impression material over the edge of the tray for better adaptation; also called muscle trimming

wax setup

sample prosthesis used to fit, adjust, and test jaw relationship of the wax denture

occlusal rims

wax block placed on the baseplate over the residual ridge of the plate

fastooning

melting, shaping, and forming of the wax rims to simulate functional and esthetic gingival tissue

centric relationship

the most retruded, unstrained position in the mandibular condyle in the glenoid fossa

retrusion

position of the mandible as far posterior as possible while in occlusion

protrusion

position of the mandible as far anterior as possible while in occlusion

lateral excursion

sliding position of the mandible from side to side, while in occlusion

vertical dimension

space height of the denture teeth while in occlusion

smile line

amount of denture tooth space that is viewed while the patient is smiling

cuspid eminence

vertical length or height of the denture cuspid placement

partial appliance

a dental prosthesis that replaces one or more teeth

crown and bridgework

when it is fixed or cemented in the mouth

removable partial denture

when the prosthesis is able to be removed at will by the patient

bilateral

partial denture replaces the teeth and structures on both sides of the arch

unilateral

partial denture replaces teeth and structure on only one side

framework

the skeleton of the partial prosthesis to which acrylic material and artificial teeth will be applied

abutment

the remaining natural tooth or implanted device that supports and stabilizes the prosthesis

connector

metal framework that unites the left and right sides of the partial appliances

palatal

major connectors may be in the form of a bar, plate, or strap, this is the connector in the maxillary and lingual in the mandibular prosthesis

saddle

mesh extension of the framework that rests on the alveolar ridge

stress breaker

a device placed in stress-bearing areas assist with occlusal forces

retainer

a clasp or removable partial denture attachment that is applied to an abutment tooth to provide retention

bar

originates at the prosthesis base or connector border and extends upward toward the tooth undercut

circumferential

a clasp that encircles a tooth more than 180 degrees with one terminal end in the undercut of a tooth crown

rest

metal projector or clasp extension that fits into the prepared area or restoration of the abutting tooth

inlay

cast restoration that sits inside of the tooth cusps and is constructed to fit in the tooth preparation of the proximal walls and a portion of the occlusal surface

onlay

cast restoration that covers one or more of the tooth cusps and is constructed to fit the tooth preparation of the proximal walls and most or all of the occlusal surface

three-quarter crown

cast restoration that is applied to a tooth prepared on all surfaces except the facial surface

full crown

cast restoration that covers the entire visible, anatomical tooth

porcelain fused to metal crown (PFM)

full cast crown restoration that has a porcelain (ceramic) veneer applied to prepared surfaces

veneer

a thin, tooth-colored shell that is applied to the prepared facial surface of a tooth

porcelain jacket crown (PJC)

thin metal and ceramic veneered crown for an anterior tooth

post and core crown (PCC)

crown for use in an endodontically treated tooth with significant loss of tooth structure

temporary crown

acrylic, aluminum, or composite crown constructed and provisionally cemented on for protection while construction of the permanent crown is completed

fixed bridge

prosthesis that replaces one or more missing teeth

cantilever bridge

prosthesis in which only one side of the device is attached to the retainer or abutment tooth

Maryland bridge

conservative, prepared resin-retained prosthesis using a bonding procedure to hold to adjacent teeth

occlusal records

measurements of jaw relationships and articulation of teeth

facebow

measurement device used to record the occlusal position

die

exact stone replica of the tooth preparation that is receiving the prosthesis

dowel pin

tapered brass post that is placed into the die when the stone is poured

wax pattern

exact wax replica of the prosthesis to be completed

separating medium

material placed upon the die before the wax is melted onto it to enable separation when completed

die relief

a space in the prosthesis to accommodate the cement process

sprue pin

a small plastic pin or wax channel area attached to the wax pattern to provide space in the investment for the entry of melted metal in the casting procedure

sprue base

a brass disc with a rounded, pyramid top used to hold the sprue pin that is attached

casting ring

small ring that is used to hold the invested pattern during the investing of the gypsum material and the casting of the melted metal

liner

ring lining material placed inside the casting ring to allow for the investment expansion

investment

gypsum, silica, and reducing-agent material prepared to maintain the shape of the wax pattern during casting

wax elimination

burn or heating out of wax pattern from hardened investment material, leaving a void in the shape of the wax pattern

casting

procedure in which melted alloy is centrifugally forced from the crucible into the casting ring to fill the void in the shape of the melted out wax pattern

zone 1

junction area when gases meet; unproductive

zone 2

combustion area, oxidizing, slightly green; not to be used

zone 3

reducing area, blush, hottest part of flame; the desirable use zone

zone 4

oxidizing area, where flame meets air; coolest part of the flame

pickling solution

solution used to remove surface film from the cast restoration

soldering

joining of two metals by the fusion of an intermediate alloy that may be silver or gold