Dent 345 Dental Waxes

7/31/2019 Dent 345 Dental Waxes

1/20

Dental

Waxes

Dent 344

August 10, 2010

a

b

c

thermoplastic molding materialthermoplastic molding material

plastic (malleable) at normal ambienttemperatures

solid at room temperature:solid at room temperature: a melting point

above approximately 45 C (113 F) (whichdifferentiates waxes from fats and oils)

a relatively low viscosity when melted (unlike

many plastics) insoluble in water

hydrophobic

Physical Characteristics

Chemical Characteristics

Type of lipid (like oils and fats)

Chemically, wax may be an ester of ethyleneglycol (ethan-1,2-diol) and two fatty acids,

This is different from a fat which is an ester ofglycerin (propan-1,2,3-triol) and three fattyacids.

A wax may also be a combination of otherfatty alcohols with fatty acids.

Dental waxes

Waxes have many applications in dentistry.

1


2/20

General Composition

BASEBASE Wax:Wax: most commonly paraffin

(1) Hydrocarbon (e.g., PARAFFIN) or esters(1) Hydrocarbon (e.g., PARAFFIN) or esters(2) High or low molecular weight (MW)(2) High or low molecular weight (MW)

MODIFIERMODIFIER Waxes:Waxes: contribute properties such asincreased hardness, stickiness, or brittleness(1) Hydrocarbon or ester types;(1) Hydrocarbon or ester types;

(2) High or low MW(2) High or low MW

COLORANTCOLORANT:: 1% for esthetic purposes and color

contrast FILLERS :FILLERS : compatible fillers help control expansioncompatible fillers help control expansion

and shrinkageand shrinkage

Insect: Beeswax

Animal: Spermaceti (Sperm whale,

3anbar)

Additives (2)

Natural Resins Rosin (Colophony, pine resin)

Copal (South America, Mayan, aromatic plant resin)

Dammar (India, East Asia, Malay word for resin)

Sandarac (NW African tree)

Mastic (Miskeh, Small Mediterranean shrub)

Shellac (Assam, Thailand, lac insect, Kerria lacca,

eats tree sap and deposits resin in tree bark which isharvested)

Kauri (Agathis evergreen tree resin)

Synthetic Resins Elvax (ethylene vinyl acetate resin)

Polyethylene

Polystyrene (used to make styrofoam packaging)

Plants : Carnauba (Brazilian palm)

Ouricury (Brazilian palm)

Candelilla (Mexican shrub)

Japan wax

Cocoa butter

Fats

Stearic acid

Glyceryl tristearate

Oils

Turpentine

Colorants

Acrawax C

Aerosol OT

Castorwax

Flexo-wax C

Epolene N-10

Albacer

Durawax 1032

Petroleum/ Mineral: Paraffin (petroleum)

Microcrystalline

Barnsdahl

Ozokerite (brown coal)

Ceresin

Montan (coal extract)

Additives (1)Synthetic waxesNatural waxes

Natural waxesNatural waxes are complex combinations of organic compounds of

high molecular weight:

Hydrocarbons, e.g. saturated alkanes,

Esters, e.g. myricyl palmitate.

Natural waxes are the primary components of dental wax.

The dental manufacturers blend the particular batches of waxes toobtain the properties desired for a particular application.

Some waxes also contain free alcohol and acid.

(Esters are formed from union of higher fatty acids with higheraliphatic alcohol with elimination of water)

Alcohol+Fatty AcidEster+Water

Synthetic waxes

High degree of refinement,no contamination. Polyethylene waxes

Polyoxyethylene glycol waxes

Halogenated hydrocarbon waxes

Hydrogenated waxes

Wax ester (fatty alcohol + acid)

2


3/20

Fats

Increase the melting range and thehardness of compound waxes.

Hydrocarbon oils - soften mixture of

waxes.

Silicone oils - improve the ease ofpolishing with waxes.

Resins

Most natural resins are obtained from trees and

plants. Insoluble in water

improve toughness, hardness, melting range of

waxes

Common Modifier Waxes

Ceresin increase the hardness and water

resistance of wax Carnauba increase the hardness and water

resistance, increase melting range

Beeswax increases the stickiness, improvesflow properties at mouth temperature.

Rosin increases the brittleness

Microcrystalline waxes reduce stressrelease on cooling

Properties of Waxes

3


4/20

Melting range

Waxes consist of similar types of molecules of

different of molecular weight. (They may contain several types of molecules )

As a result of the molecules with differentmolecular weight, waxes have a melting rangerather than melting point.

COMPOSITION (%)

TEMPERATURE(C)

Paraffin Carnauba

40

30

20

60

50

70

80

90

25 50 75 100

LIQUID

LIQUID + SOLID

SOLID

Melting Onset (Solidus)

Melting Completion (Liquidus)

Melting range Phase Diagram forParaffin- Carnauba Wax

Melting range

Occurs because of the Multiple wax mixtures

The liquidus line (representing the temperature atwhich complete melting has occurred)

The solidus line (below which the composition isentirely solid)

the solid + liquid range in between is quite broad(almost 40C). Allows normal manipulation

To develop wax flow, the temperature only needsto be heated to a point within the solid+liquid

range or up to the point of the liquidus line butnot much higher.

Excessive heating would cause decomposition.4


5/20

Heating issuesMethods: Flame heated instruments Warmth of hand

Dry heat as wax pot Warm water for indirect techniques

Flow : After the highest melting point is reached

(Liquid) 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.

Flow

Flow is dependent on the temp. of the waxes.

Flow is greatly increased as the melting point of

the wax is approached.

In solids it is similar to creep

In liquids its analogous to viscosity

Waxes are usually non-flowable at room

temperature

Temperature change is proportional 1/ viscosity

It is critical for inlay wax to have flow less than 1%

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, rollthe wax when it is in softened status (unable

to hold shape by itself)

5


6/20

Lost wax technique

- No residue on burnout

Used with cast metal techniques toprevent inclusions or

incomplete castings and voids

Wax patterns need to be burned to thepoint where no excess residue mayinterfere with metal casting

Heat melt and/or decompose wax by theprocess of oxidation which completelytransforms it into water vapor and carbondioxide so that no residue is left.

Tackiness or Stickiness

Created by the bees wax

addition in the mixture

Increased if material is warmedby hand

Solid waxes become tacky to

other material if heated

Adhesives may be applied on

casts before wax application

Dipping in bees wax increases

stickiness of refractory casts

Old wax adheres tonew one if surface is

Dry

Dripping by heat

May adhere togypsum material

Dimensional stability Wax should be dimensionally stable once

it has solidified (less than 1%).

Deformations:Plastic deformation

Under force wax is ductile.

Ductility allows it to be carved orburnished

Residual stress recovery ***

Elastic Recovery (Recoil) ***

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

6


7/20

Thermal expansion of waxes

Expand when temperature rises

Contract when temperature is decreased

Dental waxes have the largest coefficient ofthermal expansion among dental materials.

Temperature change in wax patterns may bea major contributing factor in inaccuracy ofthe finished restoration.

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.

Residual thermal stresses may changedimensions

Paraffin > beeswax >carnuba

Do notheat

above

melting

point

during

work

250ppm/C

Paraffin

Carnu

ba

Beesw

ax

0 25 30 40 4535 50

0

1.2

1.0

0.8

0.6

0.4

0.2

TEMPERATURE (C)

EXPANSION(%

)

KERRHARDWAX

Thermal Expansion Mechanical properties

Elastic modulus,Proportional limit and

Compressive Strength

of waxes are low compared with those ofother materials and these propertiesdepend strongly on the temperature.

7


8/20


9/20

Applications

Dental wax

Classification According to Use

1. Pattern waxesa. Inlay

b. Castingc. Baseplate

2. Processing waxesa. Boxing

b. Utilityc. Stickyd. Carding

3. Impression waxesa. Corrective

b. Bite-registration

4. Other (Specialty) waxes

CLASSIFICATION OF DENTAL WAXESCLASSIFICATION OF DENTAL WAXES

1. PATTERN WAX

Used to form the general predeterminedsize and contour of artificial dentalrestoration , which is to be constructed of amore durable material.

9


10/20

Pattern waxes

1.Inlay waxes

3.Baseplate waxes2.Casting waxes

Pattern waxes

Uses

metal castings of

Inlays

Attachments

Crowns

Pontics

Partial dentures

Denture base material

Inlay wax

Forms

sticks pallets, tins-Blue or green

Consistencies

-Hard, medium, soft, regular

Application

-indirect and direct techniqueRemovableRemovableDie withDie withWaxed InlayWaxed Inlay

The pattern is waxed and embedded in anappropriate investment material to form a

mold with channel or sprue leading from theouter surface of the investment mold to thepattern.

The wax is subsequently eliminated byheating & softening and the mold is further

conditioned to receive the molten metalcasting alloy.

Inlay pattern wax

10


11/20

INLAY WAX

CompositionParaffin + Carnuba + Ceresin +Beeswax + Colorants

Properties- low thermal dimensional change

-must have clean excess residue

Inlay waxes : Properties

ANSI/ADA Specification No. 4 for dental inlaycasting wax.

Type I wax = a hard wax that is prescribed for

forming direct patterns in the mouth.

Type II wax = a softer wax that is used as an

indirect technique wax.

INLAYINLAY WAXWAX

1. Overview:

a. Objective: Pattern material to accurately representdesired mold space for inlays, onlays, and crowns.

b. Requirements for Inlay Waxes:(1) Good adaptation to dies(2) Thermal stability at low temperatures(3) Complete pyrolysis at high temperatures

2. Inlay Wax Composition:

a. 60% Paraffin Wax = BASE Waxb. 25% Carnuba Wax = MODIFIER Waxc. 10% Ceresin = MODIFIER Waxd. 5% Beeswax = MODIFIER Waxe.


12/20

BASE AND MODIFIER WAXES FOR INLAY WAXBASE AND MODIFIER WAXES FOR INLAY WAX

1.08100-150Aromatic resin acidPlantROSIN

1.040-1.120~ 120Aromatic resinPlantGUM DAMMAR

0.99-0.99982-86Hydrocarbon, Ester, Fatty AcidPlantCARNAUBA

0.95-0.9968-70C21 hydrocarbonsPlantCANDELILLA

0.95-0.9662-65Ester mixtureInsectBEESWAX

0.91-0.9261-78Complex hydrocarbonsMineralCERESIN

0.9050-57Hydrocarbon mixtureMineralPARAFFIN

Density

(20C)

Melting

(C)

Composition:Origin:Name:

INLAY WAX = Paraffin + Carnuba + Ceresin + Beeswax + Colorants

COMPOSITION (%)

TEMPERATURE(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)

INLAY WAXPhysical Properties Melting Range

250ppm/C

Paraffin

Carnu

ba

Beesw

ax

0 25 30 40 4535 500

1.2

1.0

0.8

0.6

0.4

0.2

TEMPERATURE (C)

EXPANSION(%)

KERRHARDWAX

INLAY WAXPhysical Properties Thermal Expansion of Components

Mechanical PropertiesMechanical Properties::

FlowFlow < 1%< 1%

DuctilityDuctility = moderate= moderate Residual StressResidual Stress = none= none

INLAY WAXMechanical Properties and Chemical Properties

Chemical PropertiesChemical Properties::

HomogeneityHomogeneity = good= good Contact AngleContact Angle = low= low

OxidationOxidation = complete= complete

12


13/20

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

Casting wax : Composition

The ingredients are similar to those found

in inlay waxes.

Casting wax : Properties

Federal specification No U-W -140 for casting wax

Flow : 35o

C - maximum, 10 %

38o

C - minimum, 60 %

Breaking point : no fracture at 23o

+1o

Pliable and readily adaptable at 40o

to45

oC

Accurately copies surface against which itpressed

Not brittle on cooling

Vaporize at 500oC, leaving no film other

than carbon

Working properties

13


14/20

Baseplate wax

Baseplate wax derives its name from its useto form the base-plate in the technique forcomplete / partial denture prosthesis.

Normally pink or red in color.

serves as the material to produce the desired contourof the denture after the teeth are set in position

Baseplate wax

14


15/20

Base Plate wax

Form

sheetsTypes I, II & III

Application

-wax registration of ridge form

-Protruded contact position records

-Carved into tissue forms and Support teeth

-Bite registrationProperties

-melting range higher than mouth temperature

-Customised to climate

Baseplate wax : Composition

70-80 % paraffin or ceresin

small quantities of other waxes & additives.typical composition

80% ceresin - 12% beeswax

2.5% carnuaba

3% natural or synthetic resins

2.5% microcrystalline or synthetic wax

Baseplate wax : Properties

ANSI/ADA Specification No.24

Type I - Soft, building contours and veneers

Type II - Medium, patterns in mouth, temperate

Type III - Hard, patterns in mouth, hot weather

Linear thermal expansion from 25o-40

oC < 0.8%

Softened sheets shall cohere readily without becoming

flaky or adhering to fingers

No irritation of oral tissue

trim easily with a sharp instrument at 23oC

Practical requirements

15


16/20

Smooth surface after gentle flaming

No residue on porcelain or plastic teethColoring shall not separate or impregnate plaster

during processing

No adhesion to other sheets of wax or separating

paper on storage

Practical requirements

2. PROCESSING WAX

Used primarily as auxillary aids in theconstruction a variety of restorations andappliances either clinically or in thelaboratory

Processing waxes

1.Boxing waxes

2.Utility waxes

3.Sticky waxes

4.Carding waxes

Boxing waxUse to form a plaster or stone cast from an impression of

the edentulous arch

16


17/20

Boxing wax

Forms

1 inch sheetsUses

used to form base of the cast pouring

May be used to modify borders of trays

Properties

Tacky at room tempTransfer to impressionTransfer to impression

Boxing wax:Working properties

Federal specification No U-W -138

Smooth, glossy surface on flaming

Pliable at 21o

C, retain shape at 35o

C

Seals easily to plaster with hot spatula

Utility waxUsed in numerous instance

most likely consists of beeswax, petrolatum and

other soft waxes

Utility wax

Forms

Ropes manipulated at room temp

ApplicationsAdd 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

17

Utilit


18/20

Utility wax:Working properties

Federal Specification No U-W- 156

Pliable at 21o to 24oC

Tacky at 21o

to 24oC, sufficient adhesion to build up

Sticky wax

It is sticky when melt and adheres closely to the surface

on which it is applied.

It is firm, free from tackiness and brittle at room temp.

Paraffin + Rosin & yellow beeswax are the usual majorconstituents.

Sticky wax

Forms

Pencil shapeorange or yellow

Properties

hard and brittle can reorient ifbroken

Adhere temporarily the metal,

gypsum, resin for fabrication orrepair

Sticky wax : Working properties

Federal Specification No.U-W-00149a

Sticky when melt

Adhere closely

Not more than 0.2% residue on burnout

Not more than 0.5% shrinkage from

43o

to 28 Co

18


19/20

3. IMPRESSION WAX

Uses

Used for taking impression

within the mouth

For edentulous impressions

Corrects undercuts

Closes bubbles

Properties

flow at mouth temperature

E.g. Bite wax, mizzy

Korecta wax

Alu wax

Corrective impression wax

Wax Bite Registration

Uses

To articulate modelscorrectly

Forms

horse shoe shape

May be supported by

metal foil for stability

Bite registration wax

Used to accurately articulate certain models ofopposing quadrant

Formulated from beeswax or hydrocarbonwaxes such as paraffin or ceresin and containalumina or copper particle

19


20/20


Alu-wax


Occlusal indicator wax

Other waxes

Dipping wax

Other waxes

White wax occlusal registration

Wax marking pencils

20

Dent 345 Dental Waxes

Documents

Transcript of Dent 345 Dental Waxes