Waxes

Bite wax

-A wax form used to record the occlusal surfaces of teeth as an aid in establishing maxillomandibular relationships

Hygroscopic expansion

—Amount of setting expansion that occurs when a gypsum-bonded casting investment is immersed in water, which is usually heated to approximately 38 °C.

Indirect wax technique

—Procedure in which a wax pattern is prepared on a die.

Inlay wax

—A specialized dental wax that can be applied to dies to form direct or indirect patterns for the lost-wax technique, which is used for the casting of metals or hot pressing of ceramics.

Refractory

—Capable of sustaining exposure to a high temperature without significant degradation.

Sprue

-The mold channel through which molten metal or ceramic flows into a mold cavity.

Sprued wax pattern

—A wax form consisting of the prosthesis pattern and the attached sprue network.

Sticky wax

—A type of dental wax that exhibits high adhesion to dry, clean surfaces when it is heated to a plastic condition.

Baseplate wax

—Dental wax provided in sheet form to establish the initial arch form in the construction of complete dentures. This product typically contains approximately 75% paraffin or ceresin wax, beeswax other waxes, and resins.

Boxing wax

-A wax sheet form used as a border at the perimeter of an impression to provide an enclosed boundary for the base of the cast to be made from a poured material such as gypsum or resin

Burnout

—Process of heating an invested mold to eliminate the embedded wax or plastic pattern.

Corrective wax (dental impression wax)

A thermoplastic wax that is used to make a type of dental impression.

Dental wax

(1) A low-molecular-weight ester of fatty acids derived from natural or synthetic components, such as petroleum derivatives, that soften to a plastic state at a relatively low temperature.

(2) A mixture of two or more waxes and additives used as an aid for the production of gypsum casts, production of nonmetallic denture bases, registering of jaw relations, and laboratory work.

Direct wax technique

—A process whereby a wax pattern is prepared in the mouth directly on prepared teeth.

Divesting

—Process of removing investment from a cast metal or hot-pressed ceramic.

Elastic memory

—Tendency of a solid wax form to partially return to its original shape when it is stored at a higher temperature than that to which it was cooled.

Flow

—Relative ability of wax to plastically deform when it is heated slightly above body temperature.

Primarily used in the clinics

Used in commercial dental laboratories

2 GROUP OF DENTAL WAXES

● Bite registration wax

● Disclosing wax (pressure indicating paste) ● Utility wax for altering and adapting impression trays

● Low-melting type I inlay wax used in the mouth for direct wax pattern

Primarily used in the clinics

● Boxing wax

● Baseplate wax

● Sticky wax

● Beading wax

● Utility wax

● Hard, medium wax used in the mouth for type II inlay wax for indirect wax pattern

Waxes used in commercial dental laboratories

Pattern Wax

Processing Wax

Impression Wax

3 CLASSIFICATIONS OF DENTAL WAXES

Inlay waxes

Casting waxes

Baseplate waxes

Pattern Waxes

Boxing waxes

Utility waxes

Sticky waxes

Processing Waxes

Bite registration wax

Correction waxes

Impression Waxes

Pattern waxes

- Metal framework for partials and dentures

- The baseplate is layers of wax applied to the dental model to create the pattern in which the teeth will sit in the denture.

Melting range rather than a melting point

Dental waxes have a __________ of rather than a melting point. The melting range is the point the wax will start to soften and then flow

PROCESSING WAX

- Primarily used to help in dental procedures clinically and laboratory.

- There are boxing wax, utility wax and sticky wax.

Utility wax rope

- is used to adapt the impression tray. To customize the tray and aid in patient comfort.

Sticky wax

- is in orange sticks.

- It is used to glue components of metal, gypsum and resin together temporarily.

Boxing wax

- strips are 1.5" strips used as the base and sides of a gypsum mold.

Corrective impression wax

- used with other impression materials to correct undercut areas and fill in small voids.

Bite registration wax

- will melt at temperatures slightly higher than mouth temp

- is used to create wax bite registrations for articulation of models.

PARAFFIN

GUM DAMMAR/ DAMMAR RESIN

CARNAUBA WAX

CANDELILLA WAX

CERESIN

COMPOSITION OF WAXES

PARAFFIN

- Main ingredientof waxes; most dental waxes consist 40-60 by wt%

high boiling fractions of petroleum

Paraffin wax is Derived from: ____________________

1. complex mixture of hydrocarbons of methane series

2. a minor amount of amorphous or microcrystalline phases

Paraffin wax is composed of:

1.

2.

PARAFFIN

- Moldable below the liquefaction temperature

- Likely to flake when trimmed - Does not present a smooth, glossy surface (a desirable requisite for an inlay wax)

GUM DAMMAR/ DAMMAR RESIN

- A natural resin

GUM DAMMAR/ DAMMAR RESIN

○ Added to paraffin to improve the smoothness in molding

○ Makes the paraffin more resistant to cracking and flaking

GUM DAMMAR/ DAMMAR RESIN

○ Increases toughness of the wax

○ Enhances smoothness and luster of the surface

CARNAUBA WAX

- Occurs as a fine powder on the leaves of certain tropical palms

- One of the hardest and most durable waxes.

- One of the main components of inlay wax

- Has a relatively high melting point

CARNAUBA WAX

- Combined with paraffin to decrease the flow at mouth temperature

- Has an agreeable odor

- Also contributes to the glossiness of the wax surface even more than does the dammar resin

CANDELILLA WAX

- Can also be added partially or entirely to replace carnauba wax

- Also obtained from plants

- Provides the same general qualities as the carnauba wax - Has lower melting point

- Not as hard as carnauba wax

CANDELILLA WAX

Low Melting point and not as hard as carnauba

CERESIN

- Typically a white wax extracted from ozokerite, a waxy mineral mixture of hydrocarbons

- Colorless or white when pure

- Unpleasant odor

CARNAUBA WAX

High melting point wax

CANDELILLA WAX

: Low melting point waxes and not as hard as carnauba

TYPE 1-Medium Wax for direct wax pattern

TYPE 2- Soft wax for indirect wax pattern

TYPES OF DENTAL WAXES

TYPE 1 Medium Wax

- Wax employed in direct wax pattern technique

- Max. flow permitted at 37°C is 1%

- Permits carving and removal from the cavity w/o distortion

TYPE 2 Soft Wax

- Wax used in the indirect wax pattern technique

- Minimal flow 70% at 45°C and max flow of 90%

- Wax is inserted into the prepared cavity and flows into the details of the cavity

1. Should be uniform when softened.

2. The color should be in contrast with the die material or the tooth.

3. There should be no flakiness or roughness when bent or molded.

4. It should have the property of being carved to the

margins and conform to the original anatomy of the tooth.

5. It should be eliminated completely from the mold during the burn out process and should leave no

excess or residue which will affect the outcome of the cast metal.

6. It should be completely rigid and dimensionally stable at all times until it is eliminated

7. It should have the property of plasticity or flow at a temperature slightly above that of the mouth

DESIRABLE PROPERTIES OF WAX

Low Thermal Conductivity

High Coefficient of Thermal Expansion

Thermal properties of dental waxes

DISTORTION

- Most serious problem when forming and removing wax patterns from the mouth.

● Thermal changes

● Released stresses from contraction on cooling

● Occluded air

● Change of shape during molding, carving & removal

● Time and temperature during storage

Distortion is Caused by

Elastic memory

waxes return to their original shape after manipulation.

1. Never allow relaxation of the wax.

2. Do not remove the wax while still soft.

3. Avoid thermal changes, or the increase or decrease of temperature

4. Soften the wax homogenously.

5. Never create undercuts in the cavity.

6. Invest the pattern immediately after removal from the mouth or die.

Ways to prevent distortion:

1. BASEPLATE WAX

2. STICKY WAX

3. BOXING WAX

4. BITE WAXES / CORRECTIVE WAX / IMPRESSION WAX

SPECIALITY WAXES

BASEPLATE WAX

- Used principally to establish the initial arch form in the construction of complete dentures

- Supplied in 1-2mm thick red or pink sheets

- Made up of approximately 75% paraffin or ceresin with addition of beeswax and other resin or waxes

Type I - soft wax for building veneers

Type Il - medium wax for patterns to be tried in the mouth in normal climatic conditions

Type III - hard wax for trial fitting in the mouth in tropical climates

Types of Baseplate waxes

STICKY WAX

- Quite tacky when melted but firm and brittle when cooled

- Used to join and temporarily stabilize components of a bridge before soldering or the pieces of a broken denture prior to repair

BOXING WAX

- Enclosing an impression before the plaster or stone cast is poured.

- Soft and pliable and can easily be pressed to desired contour

BITE WAXES / CORRECTIVE WAX / IMPRESSION WAX

- limited to use in edentulous portion of the mouth because they distort when withdrawn from undercut areas.

- Quite soft at mouth temperature

- Have sufficient body to register the details of the soft tissue

- Are rigid at room temperature

lost-wax pattern technique

The first procedure in the casting of an inlay or crown is the _________

- It should be an accurate reproduction of the missing tooth structure.

- It forms the outline of the mold into which the gold alloy is cast.

- It should be well adapted to the prepared cavity, properly carved with minimal distortion.

- It should be invested as soon as possible after removal from the cavity.

Ideal Characteristics of lost-wax pattern technique.

DIRECT WAX PATTERN

- The wax is carved directly on the tooth itself

- uses a type I wax or medium wax.

Advantages:

● Less material is used

● Less time-consuming

Disadvantage:

● Difficult to carve

Advantages and Disadvantages of Direct Wax Pattern

1. A stick of wax is softened over a flame. Do not

overheat.

2. Twirl the wax until it becomes shiny.

3. Remove from the flame.

4. Repeat the process until the wax is warm

throughout.

5. Knead together and shape to the prepared cavity.

6. Use a sprue to remove the pattern from the tooth.

7. Avoid touching the wax with fingers to prevent

temperature change.

8. Invest the pattern immediately.

DIRECT WAX PATTERN STEPS

INDIRECT WAX PATTERN

- The wax is carved on the die. - Uses a type II wax or soft wax

Advantages

● Visibility in carving the pattern

Disadvantages

● More material is used

● More time-consuming

Advantages and Disadvantages of Indirect Wax Pattern

1. Lubricate the die. Avoid any excess as it will

prevent intimate adaptation to the die

2. Melt the wax and add it by increment or layer into

the die using a spatula or brush

3. Overfill the cavity then carve to the proper contour

4. Avoid abrading any surface of the die when

carving on the margins.

5. Use a silk cloth for final polishing of the pattern.

6. Invest the pattern immediately.

INDIRECT WAX PATTERN STEPS

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