Dental Wax Materials

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Dental Wax Materials
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Definition

• thermoplastic molding material.
• solid at room temperature.

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Types of waxes

• Baseplate wax sheets, establish initial arch
  form in construction of CD.
• Bite wax record the occlusal surfaces of teeth.
• Boxing wax sheet wax used as a border of an
  impression to provide base of the cast to be
  made.
• Inlay wax applied to dies to form direct or
  indirect patterns for the lost-wax tech.
• Sticky wax adheres to dry clean surfaces.

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General Composition

• BASE Wax that is almost always paraffin (not
  smooth, not glossy, flake when trimmed)
• (1) Hydrocarbon of paraffin or esters
• (2) High or low MW
• MODIFIER Waxes contribute properties such as
  increased hardness, stickiness, or brittleness
• (1) Hydrocarbon or ester types
• (2) High or low MW
• COLORANT 1
• Fillers some waxes contain it to control
  expansion and shrinkage of the wax product.

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Chemical composition

• Natural (mineral, vegetable, or animal origin
  and/or synthetic waxes (more homogeneous pure)
• Natural waxes are complex combinations of organic
  compounds of high molecular weight
• Hydrocarbons,e.g. saturated alkanes,
  microcrystalline wax series, carnauba wax,
  candelilla wax.
• Esters, e.g.myricylpalmitate.
• Some waxes also contain free alcohol and acid.
• (Esters are formed from union of higher fatty
  acids with higher aliphatic alcohol with
  elimination of water)
• AlcoholFatty Acid ?EsterWater

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Natural waxes Synthetic waxes Additives
Minerals Paraffin Microcrystalline Barns Dahl Ozokerite Ceresin Montan Acrawax C Aerosol,OT Castorwax Flexowax C Epolene N-10 Albacer Aldo 33 Durawax 1032 Fats Stearic acid Glyceryltristearate Oils Turpentine Color
Plants Carnauba Ouricury Candelilla Japan wax Coca butter Natural Resins Rosin Copal Dammar Sandarac Mastin, Shellac Kauri
Insect Beeswax Animal Spermaceti Synthetic Resins Elvax Polyethylene Polystyrene
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Common Modifier Waxes

• Gum dammar smoothness, resistant to flaking,
  toughness. (resin)
• Ceresin the hardness and water resistance of
  wax. Improves carving properties.
• Carnuba the hardness and water resistance,
  melting range, gives glossiness, flow
  at mouth temp.
• Beeswax the stickiness, improves flow
  properties at mouth temperature. (esters)
• Rosin the brittleness. (resin)
• Microcrystalline waxes stress release on
  cooling.

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Properties
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Melting range

• Occurs because of the Multiple wax mixtures
• The liquidus line (representing the temperature
  at which complete melting has occurred)
• The solidus line (below which the composition is
  entirely solid)
• the solid liquid range in between is quite
  broad (almost 40C). To allow manipulation
• To develop wax flow, the temperature only needs
  to be heated to a point within the solidliquid
  range or up to the point of the liquidus line but
  not much higher.
• Excessive heating would cause decomposition.

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Melting range
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Density and Melting ranges
Name Origin Composition Melting (?C) Density (20?C)
PARAFFIN Mineral Hydrocarbon mixture 50-57 0.90
CERESIN Mineral Complex hydrocarbons 61-78 0.91-0.92
BEESWAX Animal Ester mixture 62-65 0.95-0.96
CANDELILLA Plant C21 hydrocarbons 68-70 0.95-0.99
CARNAUBA Plant Hydrocarbon, Ester, Fatty Acid 82-86 0.99-0.999
GUM DAMMAR Plant Aromatic resin ca 120 1.040-1.120
ROSIN Plant Aromatic resin acid 100-150 1.08
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Heating issues

• Methods
• Flame heated instruments
• warmth of hand??
• dry heat as wax pot
• Water bath, but not for inlay wax??
• Flow
• after the highest melting point is reached.
• Temperature ? 1/ viscosity
• Flow temperature must be gt mouth temp if needed
  in solid state
• Over heating should be avoided?
• the base or modifier waxes can be decomposed.

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Flow

• In solids its analogous to creep
• In liquids its analogous to viscosity
• Waxes are usually non-flowable at room
  temperature
• Temperature ? 1/ viscosity
• It is critical for inlay wax to have flow less
  than 1

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Thermal conductivity

• It is low
• Wax should be softened evenly by
• rotation above the flame until it evenly softens
  or flows
• Tempered in a water bath alternately with the
  flame heating to allow the core to soften before
  dripping
• If a soft core of a bulk of wax is to be made,
  roll the wax when it is in softened status
  (unable to hold shape by itself)

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Lost wax technique

• Used with cast metal techniques
• Wax patterns need to be burned to the point where
  no excess residue may interfere with metal
  casting
• Heat melt and/or decompose wax by the process of
  oxidation which completely transform it into
  water vapor and carbon dioxide so that no residue
  is left.

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Tackiness or stickiness

• Created by the bees wax addition in the mixture
• Increased if material is warmed by hand
• Solid waxes become tacky to other material if
  heated
• Adhesives may be applied on casts before wax
  application
• Wax dipping in bees wax increase stickiness of
  refractory casts
• Old wax adheres to new one if surface is dry

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Dimensional stability

• Wax should be dimensionally stable once it has
  solidified (less than 1).
• Invest the pattern immediately after removal
  from the die.
• Deformations
• Plastic deformation
• Under force is by ductility.
• Ductility allows it to be carved or burnished
• Residual stress recovery
• Elastic Recovery

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Residual stress

• Residual stress reduction
• Heat material evenly
• Follow manufacturer instructions
• Invest within 30 min of carving
• Whenever wax additions are cooled. The exterior
  surface tends to cool first. The molten interior
  slowly solidifies and contracts. This encourages
  distortion or flow. Add in small increments,
  layering
• Store at low temperatures

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Coefficient of thermal expansion

• Very high
• ceramics (1-15 ppm/C)
• metals (10-30 ppm/C)
• waxes (30-600 ppm/C)
• inlay wax (250-300 ppm/C)
• ( wax pattern made in the mouth will shrink
  appreciably)
• Residual thermal stresses may change dimensions
• Paraffin gt beeswax gtcarnuba

• Do not heat above melting point during work

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Thermal Expansion
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Surface tension

• Wax is hydrophobic
• To increase its wetting a surfactant could be
  sprayed over wax to increase flow of investment
  material

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Color

• Coloring is not standardized
• Dark colors provide good color contrast for
  processing wax
• Opaque and Tooth-colored waxes provide good
  material for esthetic case presentations and
  patient education

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Applications
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CLASSIFICATION OF DENTAL WAXES
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Pattern Waxes
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Pattern waxes

• Uses
• metal castings of
• Inlays
• Attachments
• Crowns
• Pontics
• Partial dentures
• Denture base material

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Inlay wax

• Forms
• sticks pallets, tins
• Blue or green
• Consistencies
• Hard, medium, soft, regular
• Application
• indirect and direct technique

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INLAY WAX

• Composition
• Paraffin Carnuba Ceresin
• Beeswax Colorants
• Properties
• low thermal dimensional change
• flow temp higher than mouth
• must have clean excess residue

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Casting waxes

• Application
• Used for metal framework
• complete and partial dentures
• Forms
• Sheets and preformed shapes
• Properties
• low thermal dimensional change
• must have clean excess residue

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Base Plate wax

• Form
• sheets
• Types I, II III
• Application
• wax registration of ridge form
• Carved into tissue forms and Support teeth
• Bite registration
• Properties
• melting range higher than mouth temperature
• Customised to climate

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Processing wax
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Impression wax

• Uses
• For edentulous impressions
• Corrects undercuts
• Closes bubbles
• Properties
• flow at mouth temperature
• E.g. Bite wax, mizzy

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Wax Bite Registration

• Uses
• To articulate models correctly
• Forms
• horse shoe shape
• May be supported by metal foil for stability

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Boxing wax

• Forms
• 1 inch sheets
• Uses
• used to form base of the cast pouring
• May be used to modify borders of trays
• Properties
• Tacky at room temp

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Utility wax

• Forms
• Ropes manipulated at room temp
• Applications
• Add to the tray
• customize for pt mouth
• Comfort from sharp edges
• Control imp material in mouth
• Cover ortho bands and wires
• to register the bite
• Block out undercuts

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Sticky wax

• Forms
• Pencil shape
• orange or yellow
• Properties
• hard and brittle can reorient if broken
• Adhere temporarily the metal, gypsum, resin
  for fabrication or repair

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