Dental Waxes Flashcards
What state are dental waxes in at room temperature
solid
Why do we heat dental waxes
Heating converts the wax to a liquid phase that makes it easily mouldable
why do manufacturers of dental waxes blend 2 or more waxes together
this gives the material a softening temperature range over which it is a useful mouldable material
What rough melting range do we want a dental wax to have on clinic and why
Only slightly higher than the mouth temperature as any higher would make it uncomfortable for the patient
Note: In Labs, waxes may have a much higher melting range
Why is thermal expansion very important in dental waxes relative to other dental materials
Dental waxes have a higher thermal expansion and contraction than any other dental material
What can happen if a wax is heated too far above the melting range or is heated unevenly
This will cause expansion above the acceptable standards and cause inaccuracies in the final casting
What can cause dimensional changes in dental waxes on standing
The release of residual stresses
What are dental waxes composed of
Of a synthetic and then 2 or more natural waxes and small amounts of additives
Describe some properties of natural waxes that are added to dental waxes
- High molecular weight
- complex combination of organic compounds
Name some of the natural waxes that can be added to dental waxes
- Paraffin
- Microcrystalline
- Ceresin
- Carnauba
- Cendelilla
- Beeswax
- Spermaceti
What is the melting range of paraffin
40-70C
What is the melting range of Microcrystalline
60-90C
What is the melting range of Ceresin
61-78C
What is ceresin used for in dental waxes
to increase the melting range of paraffin wax
What is the melting range of carnauba
84-91C
What is carnauba used for in dental waxes
Increases the melting range and hardness of paraffin wax
What is the melting range of candelilla
68-75C
What is candelilla used for in dental waxes
Hardens paraffin wax
What is the melting range of beeswax
63-70C
Give some examples of synthetic waxes used in dental waxes
- Polyethylene
- Polyoxyethylene glycol
- Halogenated hydrocarbon
- Hydrogenated Hydrocarbon
- Wax esters
What are the melting ranges of polyethylene and polyoxyethylene glycol
- Polyethylene = 100-105C
- Polyoxyethylene glycol = 37-63C
What kinds of additives are used in dental waxes
- Gums
- Fats
- Resins
How are natural waxes classified according to origin
- Mineral = Paraffin, Microcrystalline, ceresin
- Plant = Carnauba, Candelilla
- Animal = Beeswax, Spermaceti
How do mineral and plant waxes differ based on their chemical structures
- Mineral waxes = hydrocarbons ranging from 17-44 C atoms
- Plant waxes = saturated alkanes ranging from 19-31 C atoms
How can dental waxes be classified based on their uses
- Pattern waxes = Inlay, casting and modelling waxes
- Processing wax = Boxing, Utility and Sticky waxes
- Impression wax = Occlusal registration and Corrective waxes
What kind of wax is an inlay wax
A pattern wax
What types of inlay wax are there and what are their uses
- Type 1 (medium) - Direct techniques
- Type 2 (soft wax) - Indirect techniques
Name some restorations that use inlay waxes
Inlays, onlays and crowns - these are first made in wax and then converted into metal
Inlay waxes can be used for making patterns of metallic restorations
What are the constituents of inlay pattern waxes
- Paraffin - 60%
- Carnauba - 25%
- Ceresin - 10%
- Beeswax - 4%
- Dammar resin - 1%
What properties makes paraffin need additives
It is weak and flakes on trimming
What does dammar resin do to inlay pattern waxes
improves smoothness, resistance to cracking and flaking and imparts gloss to surface
What are casting waxes used for
Used in patterns for denture framework ie construct the metal framework of partial and complete dentures
What classes of casting wax are there and describe their features
- Class A: 28 gauge, 0.4mm, pink
- Class B: 30 gauge, 0.32mm, green
- Class C: ready made shapes, blue
What are the properties of casting waxes
- Adaptable at 40-45C
- Not brittle on cooling
- Highly ductile
- Burnt out without leaving residue?
What is modelling wax also called
Baseplate wax
What is baseplate/modelling wax used for
Setting up of artificial teeth for full dentures
What are the constituents of modelling/baselpate wax
- Paraffin or cersin (70-80%)
- Beeswax (12%)
- Carnauba (2.5%)
- Natural or synthetic resins (3%)
- Microcrystalline or synthetic waxes (2.5%)
What kind of wax is sticky wax
A processing wax
What is sticky wax used for
Its an adhesive wax that is used for the temporary joining of items
- e.g. align fractured parts of acrylic dentures, align fixed partial parts before soldering
What are the constituents of sticky wax
- Resin
- Yellow beeswax
- Gum dammar
What are the properties of sticky wax
- At RT = hard and brittle
- When melted it adheres closely to the applied surface
- Sticky when melted
- Fractures when movement occurs
What is impression wax used for
Occlusal Registry
Corrective for edentulous impressions
What are the constituents of impression wax
- Hydrocarbon waxes (paraffin, ceresin and beeswax)
- Metal particles (Al or Cu)
What are the properties of impression wax
- Limited to edentulous portions of mouth as it distorts when withdrawn from undercut areas
- Soft at mouth temperature - flows at mouth temp (rigid at RT)
- Available in sheets and cakes
