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LABORATORYLABORATORYWAXESWAXES

Stephen C. BayneStephen C. BayneUniversity of MichiganUniversity of MichiganSchool of DentistrySchool of DentistryAnn Arbor, MichiganAnn Arbor, Michigansbayne@umich.edusbayne@umich.edu

OVERVIEW OF DENTAL WAXESOVERVIEW OF DENTAL WAXES

1.1. Definition Definition of dental wax = of dental wax = thermoplastic molding materialthermoplastic molding materialthat is solid at room temperature.that is solid at room temperature.

2.2. General CompositionGeneral Composition of Waxes: of Waxes:

a.a. BASEBASE Wax Wax: : (1) (1) Hydrocarbon [eg, PARAFFIN] or ester types; Hydrocarbon [eg, PARAFFIN] or ester types; (2) (2) High or low MWHigh or low MW

b.b. MODIFIERMODIFIER Waxes Waxes: : (1) Hydrocarbon or ester types; (1) Hydrocarbon or ester types; (2) High or low MW(2) High or low MW

c.c. COLORANTCOLORANT::

BASE AND MODIFIER WAXESBASE AND MODIFIER WAXES

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

GUM DAMMAR Plant Aromatic resin ca 120 1.040-1.120

ROSIN Plant Aromatic resin acid 100-150 1.08

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

CLASSIFICATION OF DENTAL WAXESCLASSIFICATION OF DENTAL WAXES

INLAY INLAY WAXWAX

1. Overview:

a. Objective: Pattern material to accurately represent desired 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. <1% Colorants = COLORANT

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)

INLAY WAXPhysical Properties – Melting Range

Image and graph source: Steve Bayne, University of Michigan, 2008

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

INLAY WAXPhysical Properties – Thermal Expansion of Components

Graph source: Steve Bayne, University of Michigan, 2008

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