05.03.2019
Dental waxes
Tatiana Porosencova
MD, PhD, University Assistant
Dental Propedeutics Department State University of Medicine and Pharmacy
“Nicolae Testemițanu”
1
Introduction
Definition
Definition
Dental waxes
Natural wax
Classification by the method of application
Pattern
Inlay
Casting
Sheet
Ready shapes
Wax-up
Baseplate
Processing
Utility
Sticky
Impression
Corrective
Bitte
ISO classification (ISO 15854: 2005) for casting inlay and baseplate wax
•The ISO recognizes 2 types of waxes which are further sub-classified
• according to their flow characteristics that represent their hardness.
•Type I (Casting wax) - for cast metal restorations
•Class 1 - Soft
•Class 2 - Hard
•Type II (Baseplate wax) - for denture bases and occlusion rims
•Class 1 - Soft
•Class 2 - Hard
•Class 3 - Extra hard
GENERAL PROPERTIES
1.Melting range
2.Thermal expansion
3.Mechanical properties
4.Flow
5.Residual stresses
6.Ductility
INLAY CASTING WAX
Uses
•The pattern for inlays, crowns is first made in wax and then
replaced by metal during casting.
•Direct and indirect techniques: If the pattern is made directly in
the tooth (in the mouth), it is said to be prepared by direct
technique (Class 2 wax).
•If it is prepared on a replica of the tooth (die), it is called
indirect technique (Class 1 wax).
BASEPLATE WAX
•Most students would be familiar with this wax. It is sometimes
referred to as modeling or Type 2 (ISO 15854) wax.
•They are classified under pattern waxes because they are used
to create the form of dentures and appliances made of acrylic
and like materials.
BASEPLATE WAX
•Ideally, these waxes should be easy to carve, should not chip
and break at try-in and should boil out without leaving any oily
residue.
BASEPLATE WAX
•Uses
1.To make occlusion rims
2.To form the contour of the denture after teeth are set.
3.To make patterns for orthodontic appliances and other
prostheses which are to be constructed of plastics.
Composition of mineral waxes
• Paraffin waxes: are straight- chain alkanes with 26–30
carbon atoms;
•melting range increases with molecular weight (MW) and is
decreased by oils (≤0.5% oil).
Composition of mineral waxes
• Paraffin waxes: On solidification and cooling, paraffins
volumetrically contract 11–15% nonuniformly.
Composition of mineral waxes
• Microcrystalline waxes: they are tougher, are more flexible,
and exhibit lower volumetric contraction.
•Affinity for oils facilitates hardness and tackiness modification.
Composition of mineral waxes
 Microcrystalline waxes: These are branched-chain hydrocarbons
(41–50 C atoms) of greater MW and melting range than paraffins;
Composition of mineral waxes
 Barnsdahl: is used to increase melting range and hardness while
reducing flow of paraffin waxes.
Composition of mineral waxes
Ozokerite: A straight- and branched-chain hydrocarbon
microcrystalline earth wax, ozokerite has a high oil affinity;
5–15%additions to paraffin waxes improve physical
properties in themelting range of 54°C.
Composition of mineral waxes
• Ceresin: is a straight- and branched-chain hydrocarbon
distillation product with higher MW and greater hardness than
paraffin waxes; additions raise paraffin wax melting range.
Composition of mineral waxes
• Montan waxes: are a mixture of long-chain esters and high MW
alcohols, acids, and resins extracted from lignite, with similar
properties to plant waxes.
•They are hard and brittle, blend well with other waxes, and raise the
melting range and hardness of paraffin waxes.
Composition of plant waxes
• Japan wax: A fat containing glycerides of palmitic, stearic, and
higher MW acids, Japan wax is tough, malleable, and sticky;
•it increases the tackiness and emulsifying ability of paraffin wax.
Composition of animal waxes
• Beeswax: An insect wax that is a complex mix of esters,
•hydrocarbons, and high MW organic acids.
Synthetic waxes
•Include polyethylene, polyoxyethylene glycol, halogenated
hydrocarbon, hydrogenated waxes, and wax esters.
•Polyethylene waxes have a MW of 2000–4000 while
polyoxyethylene waxes are polymers of ethylene glycols
with similar melting temperatures and hardnesses to natural
waxes but are poorly compatible with other waxes.
•They are used to plasticize and toughen wax films.
Properties of dental waxes
•Thermal properties such as melting point and solid–solid
transition temperature which is closely related to the softening
temperature observed in practice.
Properties of dental waxes
•Waxes are very poor thermal conductors and must be
maintained above the solid-solid transition temperature for
long enough to allow thorough softening to occur throughout
the material before moulding is attempted.
Properties of dental waxes
•The coefficient of thermal expansion .
•Dimensional stability
Properties of dental waxes
•Important mechanical properties are brittleness and the degree of
flow which a material will undergo in its working temperature
range.
Properties of dental waxes
•Mechanical properties: A major factor which determines the
mouldability and stability of a wax is its flow value.
Properties of dental waxes
•Materials should, ideally, exhibit considerable flow at the
moulding temperature
•but should show little or no flow at mouth temperature
•or room temperature so that they are not easily distorted.
Properties of dental waxes
•Brittleness is another important property which the manufacturers
•can, to some extent, control.
Properties of dental waxes
•Apart from their uses as impression materials, the
•major applications of waxes in dentistry are as
•modelling waxes and inlay waxes, collectively
•termed pattern waxes.
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