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DENTAL WAXES
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Contents:
❖ Introduction
❖ Components of waxes
❖ Classification of waxes
❖ Properties
❖ Pattern waxes
❖ Processing waxes
❖ Impression waxes
❖ CAD-CAM waxes
❖ Conclusion
❖ References
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INTRODUCTION
⮚DEFINITION:
“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 relatively low temperature.”
- Phillip’s science of dental materials, 12th ed
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⮚ Many varieties of waxes are used in dentistry as important
auxiliary materials in clinical and laboratory procedures for
processing, pattern making and during fabrication of oral
appliances.
⮚ They are essentially, soft substances with poor mechanical
properties.
⮚ Waxes are polymers containing hydrocarbons of low molecular
weights 400-4000, carbon atoms 14-52 and their derivatives
esters, alcohols and sometime free acids.
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Classification of dental waxes
ACCORDING TO APPLICATIONS
PATTERN
WAXES
• Inlay
• Baseplate
• Casting
PROCESSING
WAXES
• Boxing & beading
• Sticky
• Utility
• Carding &
blockout
• White & carving
IMPRESSION
WAXES
• Corrective
impression
• Bite
Registration
• Disclosing
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ACCORDING TO ORIGIN
NATURAL WAXES
MINERAL
PLANT
SYNTHETIC WAXES
ANIMAL
INSECT
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COMPONENTS OF WAXES
⮚ NATURAL WAX:
⮚ Mineral origin:
These are obtained as byproducts in
petroleum refineries.
• Paraffin
• Micro-crystalline
• Barnsdall
• Ozokerite
• Ceresin
• Montan
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⮚ Plant origin:
• Carnauba wax – Copernica cerifera
• Candelilla wax – E. cerifera, E. Antisyphilitica
• Japanese wax - Rhus sp., Toxicodendron sp.
• Ouricury wax - Syagrus coronata
• Castor wax - Castor oil
• Cocoa butter
The waxes of plants are mixtures of substituted long-chain aliphatic
hydrocarbons, containing alkanes, alkyl esters, fatty acids, primary
and secondary alcohols, diols, ketones, aldehydes.
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⮚ Animal origin:
•
•
•
•
Bees Wax – honey bees
Shellac wax – kerria lacca
Chinese wax – scale insect, ceroplastis ceriferus
Spermaceti
Beeswax is a brittle material having melting temperature ranges 63–70°C.
It is a mixture of saturated and unsaturated hydrocarbons, organic acids and
myricyl palmitate.
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⮚ SYNTHETIC WAXES
• These waxes are complex organic compounds of varied
chemical composition.
• Differ from natural wax as they have a high degree of
refinement in contrast to contamination seen in natural waxes.
• Include – Polyethylene waxes , Polyoxyethylene glycol waxes,
Halogenated hydrocarbon waxes
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ADDITIVES:
⚫Resins:
⚫Most of the resin are from plants and trees except for
shellac (insects).
⚫Natural resins such as dammar and kauri when mixed with
wax produce harder products.
⚫Synthetic resins are added to paraffin waxes to improve
their toughness, film forming character, melting range.
⚫Gums:⚫Many waxes obtained from plants and animals resemble in appearance to group
of substances described as gums.
⚫Most gums are complicated substances, and when mixed with water they either
dissolve or form sticky, viscous liquids.
⮚
Fats:
⮚ Chemically fats are composed of esters of various fatty acids with glycerol
and are known as glycerides.
⮚ Both wax and fats are tasteless, colorless and odorless in their pure form and
feel greasy to touch.
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Important properties of waxes
Thermal properties:
1. Melting range
2. Thermal expansion
3. Thermal conductivity
Mechanical properties:
1. Flexibility and modulus of elasticity
2. Flow
3. Residual stresses
4. Ductility
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Thermal properties
1. MELTING RANGE:
• Waxes consists of several types of molecules with different molecular
weight. So, they have a melting range, than a single melting point.
▪ Paraffin wax – 44°C-62°C
▪ Bees wax - 60°C-70°C
▪ Carnauba wax - 50°C-90°C
▪ Microcrystalline waxes – 65°C-90°C
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2. COEFFICIENT OF THERMAL EXPANSION:
⚫When waxes are heated, there occurs large volume expansion & sudden
increase of softness, and waxes become mouldable.
⚫Waxes have very high COTE, 150- 400ppm/°C & it increases with
temperature.
⚫Due to large COTE wax patterns contract to 0.3%- 0.8% when cooled to
room temperature.
3. THERMAL CONDUCTIVITY:
The thermal conductivity of the waxes is low, and sufficient time must be
allowed both to heat them uniformly throughout and to cool them to body
or room temp.
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Mechanical properties
1. FLEXIBILITY & MODULUS OF ELASTICITY:
• Flexibility & Modulus of elasticity, proportional limit & compressive strength
are less for waxes.
2. FLOW:
• Flow of waxes is desirable as a part of molding process but becomes
undesirable after the wax pattern or impression has been made.
• Mineral waxes –
❖ Paraffin, ceresin – 50% flow at mouth temp.
❖ Yellow Bees wax – No flow at 32°c.
70% flow at 40°c.
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3. RESIDUAL STRESS:
• It is the stress remaining in a wax as a result of manipulation
during heating, cooling, bending, carving or other manipulation.
• The patterns are strained and stressed if the softening, moulding,
and cooling is not done properly.
• These internal stresses gradually undergo distortion by relaxation
of internal stresses.
• Like other thermoplastics, waxes tend to return partially to their
original shape after manipulation. This is known as elastic
memory.
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4. DUCTILITY:
• Ductility increases with temperature.
• Waxes have higher ductility if their melting temperature is lower.
• Highly refined waxes are quite brittle.
• Wide melting ranges – greater ductility.
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ACCORDING TO APPLICATIONS
PATTERN
WAXES
• Inlay
• Baseplate
• Casting
PROCESSING
WAXES
• Boxing & beading
• Sticky
• Utility
• Carding &
blockout
• White & carving
IMPRESSION
WAXES
• Corrective
impression
• Bite
Registration
• Disclosing
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PATTERN WAXES
These waxes are used to prepare predetermined size and contour of
an artificial dental restoration which is to be constructed from a
more durable material such as cast gold alloys, Co-Cr alloys, Ni-Cr
alloys or polymethyl methacrylate resins.
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Inlay waxes (type I and type II)
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3
Casting waxes
Base plate waxes (type I, type II and type III)
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INLAY WAX
⚫ADA specification no.- 4
⚫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 ceramics.
Mode of supply:▪ Blue, green, ivory or deep purple colors.
▪ Blocks, Pellets and sticks.
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COMPOSITION:
Ingredients
Paraffin wax
Weight%
60%
Functions
Establishes melting point and
provides mouldablitiy
Carnauba wax
20%
Increases melting range and
decreases flow at mouth
temperature
Ceresin wax
5%
Modifies the toughness
Gum dammer
3%
Improves smoothness
Beeswax
5%
Reduces the brittleness of the
wax
Synthetic resins
2%
Stable flow properties
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Classification
TYPES:
Type I – Medium wax – direct pattern
Type II – Soft wax – indirect technique
Ideal requirements of inlay wax:
• Wax should be uniform when softened.
• Wax should not fragment into flakes or similar surface particles
when it is moulded after softening.
• When wax melts and is vaporized at 500 °C, it should not leave
a solid residue that amounts to more than 0.10%.
• At oral temperature, type I inlay wax must have essentially
limited flow to minimize the possibility of distortion of the
pattern during removal from the tooth cavity.
• It must be able to closely adapt to the prepared portions.
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Properties
Flow property•
ADA requirements
▪ at 45°c -type I and II – flow 70-90%.
▪ at 37°c– type I should not flow more than 1%.
▪ at 30°c– type II should not flow more than 1%.
• The flow is restricted for type I wax, since it is used for
fabrication of direct wax pattern.
• This permits carving and removal of the pattern from the
prepared cavity at oral temperature with out distortion.
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THERMAL PROPERTIES
Thermal conductivity:
• Thermal conductivity of waxes is low and sufficient time is required to heat wax
uniformly and cool them to body or room temperature.
Coefficient of thermal expansion:
• Paraffin has the highest COTE.
• The wax may expand as much as 0.7% with an increase in temperature of
20 °C or contract as much as 0.35% when it is cooled from 37 °C to 25 °C.
• If the waxes are allowed to cool under pressure its thermal properties are
changed when reheated.
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▪
The thermal dimensional change may be
affected by the previous treatment of the
wax.
▪
The expansion rate increases abruptly above
approximately 35 °C.
The temperature at which a change in rate occurs is known as the glass transition
temperature. Some constituents of the wax probably change in their crystalline
form at this temperature, and the wax is more plastic at higher temperatures.
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Wax distortion:
Distortion is due to any method of manipulation that increases
inhomogeneity of wax involving the intermolecular distance.
Distortion of a wax pattern results from
• Occluded air in the pattern,
• Physical deformation (during moulding, carving, or removal),
• Release of stresses “trapped” during previous cooling(residual
stresses).
• Excessive storage time and
• Extreme temperature changes during storage.
The waxes have elastic memory, they tend to return back to their
undisturbed state.
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Heating of inlay wax
Warm water
Bunsen burner
Infra red lamp
Wax annealer
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WAXING INSTRUMENTS
⮚ PKT Instruments
Dr. Peter K Thomas introduced hand instruments for waxing
procedures.
Among the popular instruments are PKT’s from No 1-5.
No 1 and 2 – wax addition instruments.
No 3 - burnisher for refining occlusal anatomy.
No 4 and 5 – wax carvers.
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WAX PATTERN
There are two methods of obtaining wax counterparts of
prepared cavities:
1. Direct technique
2. Indirect technique
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2. CASTING WAX
Composition:
Ingredients
Functions
1.
Paraffin wax
To establish melting point.
2.
Ceresin wax
Improve carving characteristics.
3.
Bees wax
Reduces flow at mouth temperature &
brittleness of the wax.
4.
Natural resins
Gives suitable flow properties to the wax.
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⚫Classification of casting waxes:⚫Class a (28 gauge)
⚫Class b (30 gauge)
⚫Class c (pre-formed shapes)
⦿ Mode of supply:◼ Sheets.
◼ Ready made shapes:- round rods, half round
rods, half pear shaped rods
◼ Also in bulk form roles for sprues and vent
sprues.
◼ Preformed wax patterns for cast RPD frame
work.
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⦿ Properties:-
◼ Maximum Flow at 35°C is 10%.
◼ Minimum Flow at 38°C is 60%.
◼ Vaporizes at 500°C, leaving no residue.
• Uses:• To make metallic framework of RPD.
• To give uniform thickness in certain areas of partial denture
framework.
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3. BASEPLATE WAX OR MODELLING WAX
⦿ Composition:-
Ingredients
Weight %
Functions
1.
Ceresin wax
80%
Improves carving characteristics.
2.
Bees wax
12%
Reduces brittleness, reduces flow at
mouth temperature & gives glossy
surface.
3.
Natural or
synthetic resin
3%
Gives stable flow properties.
4.
Microcrystalline
wax
2.5%
To establish required melting point.
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▪ Types:According to ADA specification no. 24, they are classified as,
• Type I: Soft wax – building contours and veneers.
• Type II: Medium wax – fabrication of patterns in the mouth – in
normal climatic conditions.
• Type III: Hard wax - fabrication of patterns in the mouth – hot
weather (temperate conditions).
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⦿ Mode of supply:-
◼ In form of sheets of pink/red
colour.
◼ Dimensions:- 8cm – breadth
15 cm - length
1- 2mm – thick.
⚫Properties:–
⚫Not irritate oral tissue.
⚫Softened sheets should co-adhere readily without becoming flaky or
adhering to fingers.
⚫Smooth surface after gentle flaming.
⚫Trim easily with a sharp instrument.
⚫No residue on porcelain or plastic teeth.
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⮚ Uses
⮚ To make occlusal rims and register
the vertical dimension.
⮚ Holding artificial teeth to base plates.
⮚ Extension of the impression tray.
⮚ Patterns for orthodontic appliances
and prosthesis other than complete
dentures.
⮚ Spacer in custom tray for complete
dentures.
⮚ Checking the occlusal clearance after
crown preparation.
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PROCESSING WAX
These are used mainly as accessory aids in construction of variety of
restorations appliances either in clinics or in the laboratory.
Carving
wax
Block
out wax
White
wax
Boxing
and
beading
wax
Utility
wax
Sticky
wax
Carding
wax
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1. BOXING AND BEADING WAX
• Mainly used to bead and box the impression to get the cast with the
required size and shape.
• Consists of low melting point hydrocarbons, bees wax and Fillersto increase the rigidity.
• Mode of supply:• Boxing wax – sheets of 3 cm width, 15-30 cm length and 3 cm
thickness.
• Beading wax- ropes of about 3-4 mm thick.
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• Properties:
• It preserves the extension.
• Controls the form and thickness of the base of the cast.
• Conserves the stone.
• It is pliable , so it can be adapted easily.
• Sticky, hence can be attached easily to the impression.
• Uses:
• Used to form a box or a wall around impressions, this gives more
uniform cast.
• To produce desired size and form of the base of the cast.
• To preserve certain landmarks of the impression.
• It can be used to reline or rebase dentures ( as it flows when it is
subjected to controlled pressure).
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⮚ Adaptation of beading and boxing waxes:-
⮚ Beading wax is adapted around the periphery of the impression.
⮚ Beading wax should be approximately 4mm wide and 3-4 mm
below the borders of the impression.
⮚ The height is adjusted until a boxing wax strip extends 13 mm
above the highest point of the impression.
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2. UTILITY WAX
• Consists mainly of bees wax, mineral wax and other soft waxes.
• Supplied in the form of cakes, sticks, & sheets.
• Has adhesive nature and it can easily stick to the tray.
• Uses:
• To give desired contour to the perforated tray for hydrocolloids.
• To build up flange of tray and raise palatal portion of tray
posteriorly.
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3. STICKY WAX
• It is composed of yellow bees wax, paraffin and rosin.
• It is firm, free from tackiness and brittle at room temperature.
• Uses:• It holds the broken pieces of a denture together during denture repair.
• Assembles the components of FPDs and wrought partial dentures in
preparation for soldering.
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4. CARDING WAX
• Used to mount teeth.
• Used for attaching broken parts of the denture before denture
repair procedures.
• Also used to join metal pieces in soldering procedures.
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5. WHITE WAX
⮚ Used for making patterns to simulate a veneer
facing.
⮚ Diagnostic wax up
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6. BLOCK OUT WAX
⮚Used to fill voids and undercuts during fabrication of removable
partial denture.
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7. CARVING WAX:
⮚ Used for tooth modelling and carving procedure in dental
anatomy, lab procedure
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IMPRESSION WAXES
• Used to record non-undercut edentulous portions of the mouth.
• Generally used in combination with other impression materials such as
polysulfides, ZOE impression paste or impression compound.
• Important impression waxes are,
• Corrective impression waxes
• Bite registration wax
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1. CORRECTIVE IMPRESSION WAXES
• Used as a wax veneer over an original impression to register the detail of
the soft tissue.
• Consists of Paraffin, ceresin and bees wax.
• The flow at 37°C is 100%. So, they can get distorted while removing from
mouth.
• Uses:• Functional impression in case of partial dentures & obturators.
• To record posterior palatal seal in dentures.
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2. BITE REGISTRATION WAX:
• They consists of
▪ bees wax,
▪ paraffin wax &
▪ ceresin wax.
• The flow at 37°C ranges from 2.5% to 22%.
• Supplied as U- shaped thin sheets, which are sometimes metallised
or foil laminated.
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• Ideal requirements of bite registration wax :-
• It should be rigid or resilient, with minimal dimensional change.
• It should be easy to manipulate.
• It should accurately record the incisal and occlusal surfaces of teeth.
• A very important feature - it should be verifiable.
• Uses:
⮚ Registration of bite both in mouth & dies.
⮚ To accurately articulate certain models of opposing quadrants.
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BITE REGISTRATION
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CAD – CAM WAX
• Preparation of wax patterns using CAD CAM machines is produced using the
milling technique based on a virtual model created from the digital data that are
obtained from the oral cavity.
• Bloomden - Pure white (translucent) wax discs are dental CAD/CAM - wax
block, which is made from zirconia ceramics powder with Cold Isostatic
Pressed(CIP).
• Produce dental wax-ups with superior margin lines and smooth surface finish.
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Conclusion
• Restorative dentistry cannot be completed without use of wax as
they are used for some of the highest precision work in dentistry.
• Dental waxes are used in many dental procedures such as wax
patterns for inlays, crowns, pontics, complete dentures and partial
dentures. They are also very useful in recording bite impressions
and edentulous areas of the oral cavity.
• The successful use of waxes must be with a full understanding of
waxes characteristics.
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REFERENCES & cross references
⚫Applied dental materials, 8th edition, John F McCabe & Angus
W G Walls
⚫ Anusavice KJ Phillips’ Science of dental materials 12th
edition.
⚫Science of dental materials- Bhat And Nandish.
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THANK YOU
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