Chapter 19: Dental Laboratory Procedures

Denturist

Person who independently specializes in denture construction

Ceramist

An expert in construction of dental ceramic appliances

Work order

Written directions from the dentist to the laboratory completing the case

Working days

Amount of time required by the laboratory to complete a prescription; is included in the appointment setup

Articulator

Mechanical device that stimulates jaw joint actions

Model trimmer

Grinding, motorized, abrasive disc device used to trim or remove excess gypsum on the diagnostic casts in preparation for placement on articulators or for models that may be used as a visual records of mouth conditions for patient education and treatment planning

Gypsum mixing machine

Device used for mechanical mixing of gypsum products; the machine also has a vacuum process to eliminate air bubbles in the mixture

Vibrator

Small table model appliance with a platform to hold bowls of freshly mixed gypsum; used to gently shake or vibrate air bubbles to the top of the mixture

Furnace

Heating device with high temperature range (up to 2000C or 3632F); used to melt out the wax patterns from the investment material; similar to a pottery kiln, but smaller

Waxing unit

Heater unit to melt and hold lab locks (50-120C, 122-248F) in a liquid state for use in laboratory construction procedures

Waxing pens/pencils

Handheld electrical heating device with various insert tips use the carb and mold wax patterns

Oven

Hot air heat devices to prepare materials 100-480C (200-900F)

Bath

Hot oil, or water heat device to prepare materials 200C (350 F) temperature

Hydrocolloid conditioning machine

Heating device that uses water to condition and prepare reversible hydrocolloid material for impressions. The machine has three compartments for graduated heated water baths

Burner

Heating device to externally heat and object not contained within it, for example, Bunsen burner or microtorch; used to heat wax for carving or sheets of base plate wax for models

Vacuum formers

Device used to heat acrylic sheets and vacuum pressure them to a prepared form for construction of a custom impression tray, mouthguard, surgical template, or tooth bleaching trays

Electroplating unit

Electrical device used to apply alloy materials to surface objects, such as dies; the alloy covering on the Stone die protects the surface of the die during fabrication

Blowtorch

A compressed gas/chemical fuel heating device used to melt alloy for castings

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; may use pressurized heat for bonding materials and substances

Sandblasting machine

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

Lathe

Electrical motor with with extended rods for attachment of appliances (abrasive disc, ragwheels, bur chuck, etc) for sanding, smoothing, and shaping of materials

Splash pan

Receptacle with high back that is inserted under the lathe wheel ends; helps to maintain a clean area

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 soothering

Denture

A removable appliance to replace an entire arch of missing teeth; partial is an appliance that replaces a few missing teeth in an arch

Full mouth denture set

A complete replacement for the maxillary and mandibular arches; compose 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

Denture that is placed into the mouth at the time of teeth extraction

Overdenture

Prosthetic denture that is prepared to fit and be secured upon posts

Denture base

Pink acrylic part of the denture that fits over and covers the alveolar ridge (gum); can be shaded light or dark pink, ethnic, or clear palate

Denture teeth

Artificial teeth use in denture construction; may be porcelain or acrylic material and supplied on anterior or posterior “cards”, deferring in shape, color, and material

Denture flange

Projecting rim or lower edge of a prosthesis; used to stabilize

Denture post dam

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

Impression tray

Maybe custom made or purchase commercially as plain or perforated, full Arch (upper and lower), quadrant (right and left), or anterior (universal) in metal or plastic material. Used to hold material for impression procedure

Spacer

Substance, usually wax, placed on a cast surface to allow impression material space

Stop

Indent or hole cut into the wax spacer 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

Molding is also called

Muscle trimming

Wax setup

Sample prosthesis used to fit, adjust, and test jaw relationship of the wax denture. Made of base plate wax, shellac, or thermoplastic material formed in constructed on a model of patient's mouth, the base plate will become the pattern for the denture base

Occlusal rims

Wax blocks placed on contoured base plate wax in preparation for dentures; the rims are used for placement of denture teeth while mounted on the articulator

Festooning

To trim and finish off; melting, shaping, and forming of the wax rims to simulate functional and esthetic gingival tissue

Centric relationship

Occlusal relationship of the teeth occurring when biting on posterior teeth; a seated mouth closure

Retrusion

Jaw position with the mandible drawn as far backward (posterior) as possible while in occlusion

Protrusion

Position of the mandible as far anterior (frontward) as possible while in occlusion

Lateral excursion

Measurement and 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 tooth space viewed while the patient is smiling

Cuspid eminence

Vertical length or height of cuspid placement in denture construction

Partial appliance

A dental prosthesis that replaces one or more teeth

Crown and bridgework

Whenever a prosthesis is fixed or cemented into the mouth

Removable partial denture

When a prosthesis is able to be removed at will by the patient

Bilateral

Partial denture that replaces the teeth and structures on both sides of the arch

Unilateral

Partial denture that replaces teeth and structure on only one side

Framework

Metal skeleton or spine onto which a removable prosthesis is constructed

Abutment

Natural tooth or implanted device prepared to hold and stabilize prosthesis

Connector

Metal framework used to unite the left and right sides of the partial appliance. Maybe in the form of a bar, plate, or strap. These May unite the framework with saddles.

What is the term of a connector in the maxillary prosthesis?

Palatal

What is the term of a connector in the mandibular prosthesis?

Lingual

Saddle

Mesh extension of the framework that rests on the alveolar ridge. The mesh will be covered with pink acrylic material to resemble oral tissue.

Stress breaker

Device applied in a stress bearing location to provide a safe breakage area

Retainer

A class or removable partial denture attachment that is applied to an abutment tooth to provide retention; may be clasp type or an intracoronal retainer and fabricated as a cast, wrought wire, or combination of the two.

The two types of clasps are

• Bar

• Circumferential

Bar clasp

Originates at the prosthesis base or conductor border and extends upward toward the tooth undercut; uniting one side of an appliance to the other side, such as palatial bar (maxillary) and lingual (mandibular) bar

Circumferential clasp

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

Rest

Small extension of removable prosthesis made to fit or seated atop The adjoining teeth

What are the components of partial dentures? (7)

• Framework

• Abutment

• Connector

• Saddle

• Stress breaker

• Retainer

• Rest

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

Past restoration that covers one or more of the tooth cusps and is constructed to fit the tooth preparation of 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 metal crown with all surfaces covered with a porcelain veneer

Veneer

Thin, resin, tooth shaped layer applied to tooth surface

Porcelain jacket crown (PJC)

A thin metal and ceramic veneered crown for an anterior tooth

Post and core crown (PCC)

Crown used for endodontically treated tooth with significant tooth loss. Has an internal post to fit into the pulp chamber and the prepared core to give full coverage and strength.

Temporary crown

Acrylic, aluminum, or composite crown prepared in the impression and provisionally cemented onto the prep for protection until the permanent crown is ready

Fixed bridge

Crosby says that replaces one or more missing teeth; usually involves adjoining teeth (abutment) to space and is therefore termed crown and bridge prosthesis

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; may be used in either anterior or posterior area

Occlusal records

Measurements of jaw relationships and articulation of teeth; measurements are obtained with impressions and/or articulation devices

Facebow

Metal orthodontic arch bow device that attaches to intraoral buccal tubes; headgear

Die

Exact Stone replica of the tooth preparation that is receiving the prosthesis, usually made of dental Stone and may be electroplated for extra strength.

Dowel pin

Tapered brass post placed into a die when the stone is poured; used as a handle of the die during the waxing and carving of the pattern

Wax pattern

Extra replica of the prosthesis to be completed semicolon prepared by melting wax on the dye and carving it to proportion.

The wax pattern is invested (encased) in?

A gypsum product, then melted out to leave a form or shape for the casting of the alloy reproduction

Separating medium

Material placed on the die before wax is melted upon it, to ease separation.

A thicker separating medium may be applied to?

Provide die relief, a space in the prosthesis to accommodate the cement process

Die relief

A space in the prosthesis to accommodate the cement process

Sprue pin

Small plastic pin in the wax pattern to hold the wax during the investment process

Casting ring

Small rings, 1-3/8” by 1-1/4”, which is used to hold the invested of the gypsum material and the casting of the melted metal

Liner

A thin coat of material that provides a barrier against chemical leakage into tooth structure; a ring lining placed inside the casting ring to allow for investment expansion

Investment

Gypsum, silica, and reducing-agent material prepared to surround and hold the shape of the wax pattern during casting; may be mixed and place into the ring with a vacuum machine or by hand

Wax elimination

Burn out of wax pattern from investment material, leaving a shape void. Completed in the lab furnace.

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.

A casting is completed with?

Passing machine - either electrically heated and forced or manually melting in the alloy and force casting - or by throwing the melted material into the void through a spring action release

Blowtorch Zone 1

Junction area when gases meet; unproductive

Blowtorch Zone 2

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