Post on 05-Jan-2016
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thermoplastic molding material.thermoplastic molding material.solid at room temperature.solid at room temperature.
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- 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.3
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BASE Wax: BASE Wax: that is almost always paraffin (not smooth, not glossy, flake when trimmed)
(1) (1) Hydrocarbon of paraffin or esters Hydrocarbon of paraffin or esters (2) (2) High or low MWHigh or low MWMODIFIERMODIFIER Waxes Waxes: : contribute properties such
as increased hardness, stickiness, or brittleness(1) Hydrocarbon or ester types; (1) Hydrocarbon or ester types; (2) High or low MW(2) High or low MWCOLORANTCOLORANT: : 1% FillersFillers: some waxes contain it to control : some waxes contain it to control
expansion and shrinkage of the wax expansion and shrinkage of the wax product. product.
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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)
Alcohol+Fatty Acid Ester+Water 7
Natural waxes Synthetic waxes AdditivesMinerals: Paraffin Microcrystalline Barns Dahl Ozokerite Ceresin Montan
Acrawax CAerosol,OTCastorwaxFlexowax CEpolene N-10AlbacerAldo 33Durawax 1032
FatsStearic acidGlyceryltristearate
OilsTurpentineColor
Plants :Carnauba Ouricury Candelilla Japan wax Coca butter
Natural ResinsRosinCopalDammarSandaracMastin, Shellac Kauri
Insect: Beeswax
Animal: Spermaceti
Synthetic ResinsElvaxPolyethylene Polystyrene8
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. 9
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Occurs because of the Multiple wax mixturesThe 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 40°C). To allow manipulation
To develop wax flow, the temperature only needs to be heated to a point within the solid+liquid range or up to the point of the liquidus line but not much higher.
Excessive heating would cause decomposition.
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COMPOSITION (%)
TE
MP
ER
AT
UR
E (
C)
Paraffin Carnuba
40
30
20
60
50
70
80
90
25 50 75 100
LIQUID
LIQUID + SOLID
SOLID
Melting Onset (Solidus)
Melting Completion (Liquidus)
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Name: Origin: Composition: Melting(C)
Density(20C)
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
GUMDAMMAR
Plant Aromatic resin ca 120 1.040-1.120
ROSIN Plant Aromatic resin acid 100-150 1.08
Methods:1. Flame heated instruments2. warmth of hand??3. dry heat as wax pot4. Water bath, but not for inlay wax??
Flow : after the highest melting point is reached. Temperature 1/ viscosity Flow temperature must be > mouth temp if
needed in solid state
Over heating should be avoided?the base or modifier waxes can be decomposed.
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In solids its analogous to creepIn liquids its analogous to viscosityWaxes are usually non-flowable at room
temperatureTemperature 1/ viscosityIt is critical for inlay wax to have flow less
than 1%
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It is lowWax 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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Used with cast metal techniquesWax 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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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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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
Residual stress reduction Heat material evenlyFollow 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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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 > beeswax >carnuba
Do not heat above melting point during work
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250ppm/C
Par
affi
n
Carnuba
Bee
swax
0 25 30 40 4535 500
1.2
1.0
0.8
0.6
0.4
0.2
TEMPERATURE (C)
EX
PA
NS
ION
(%
)KERRHARDWAX
Wax is hydrophobicTo increase its wetting a surfactant could be
sprayed over wax to increase flow of investment material
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Coloring is not standardizedDark 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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Usesmetal castings of
InlaysAttachmentsCrownsPonticsPartial dentures
Denture base material
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Formssticks pallets, tins-Blue or green
Consistencies-Hard, medium, soft, regular
Application -indirect and direct technique
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RemovableRemovableDie withDie withWaxed InlayWaxed Inlay
CompositionParaffin + Carnuba + Ceresin +Beeswax + Colorants
Properties-low thermal dimensional change
-flow temp higher than mouth-must have clean excess residue
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ApplicationUsed for metal frameworkcomplete and partial dentures
FormsSheets and preformed shapes
Propertieslow thermal dimensional changemust have clean excess residue
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Formsheets 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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UsesFor edentulous impressions Corrects undercutsCloses bubbles
Propertiesflow at mouth temperature E.g. Bite wax, mizzy
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Uses To articulate
models correctlyForms horse shoe shapeMay be supported
by metal foil for stability
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Forms 1 inch sheetsUses used to form base of the cast pouringMay be used to modify borders of trays PropertiesTacky at room temp
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Transfer to impressionTransfer to impression
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Forms Ropes manipulated at room tempApplicationsAdd 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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FormsPencil shapeorange or yellow Propertieshard and brittle – can reorient if brokenAdhere temporarily the metal, gypsum, resin – for fabrication or repair
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Thank you