E2L1: DENTAL WAXES

thermoplastic polymer

wax is a

molded

what can you do with wax regardless of its temperature?

paraffin

derived from petroleum

base wax

paraffin is the ___ for most dental waxes

• flakes when trimmed

• does not produce a smooth glossy surface

• determines the melting point if wax

paraffin characteristics

more paraffin = higher melting point

how does paraffin determine melting point of wax?

micro-crystalline wax

derived from heavier petroleum fractions

• higher melting point

• tougher

• more flexible

micro-crystalline compared to paraffin

gum dammar

natural resin

• improved smoothness

• makes wax resistant to cracking/flaking

gum dammar characteristics

carnauba wax

derived from carnauba palm

• high melting point

• decreases flow of paraffin

• improves glossiness

characteristics of carnauba wax

candelillia wax

plant-based wax

• alternative to carnauba wax

• lower melting point

characteristics of candelilla wax

montan wax

mineral wax from coal and shale

ceresin

ozokerite

• polyethylene

• hydrogenated wax

• polyethylene gylcol

other synthetic waxes

• inlay wax

• casting wax

• baseplate wax

pattern waxes

• utility wax

• sticky wax

• boxing wax

processing wax

• bite wax

• disclosing wax

impression waxes

pattern waxes

used to form the outline of a prosthesis

• higher CTE (will shrink more as it cools)

• high melting point

inlay wax for direct technique characteristics

#4

ADA specification for inlay wax

dipping wax

kept in molten liquid form and indirect

casting wax

used to make the metallic framework for removable partial dentures

• do not contain synthetic materials

• more high-molecular-weight molecules

• excellent sculpting characteristics

• quick cooldown time

• ability to remain opaque

casting wax characteristics

baseplate wax

used to establish the initial arch form and construction of complete dentures

1-2 mm

denture bases are supplied in ___ red or pink sheets

type 1

soft

type 2

medium

type iii

hard

#24

ADA specification of baseplate wax

shellac baseplate wax

wax derived from lac beetle

lost wax technique

used for indirect restorations (creating wax pattern on gypsum model)

processing wax

role is to simplify dental procedures

utility wax

can adhere to dry surfaces when pressed on and moldable even without high temperature

• perforated impression trays when taking hydrocolloid impressions

• sprue material

• orthodontics

• beading impression

where can we use utility wax?

sticky wax

tacky when melted, but firm and brittle when cooled

• fasten gypsum model components

• stabilize components of metal before soldering

• attach pieces of a broke denture during repair

sticky wax uses

boxing wax

used to enclose an impression before gypsum product is poured and is relatively soft and pliable

impression waxes

can distort if withdrawn from undercut areas

bite wax

to obtain the patient’s articulation or bite and copy it when mounting the models

base plate wax

can also be used to get your bite registration

disclosing wax

used to identify parts of the denture that need relief

• corrective wax

• pressure indicating paste

disclosing wax is also called ___

1. uniform when softened

2. color: contrast with die material/teeth to facilitate proper finishing of margins

3. not fragment into flakes during carving after cooling

4. not be pulled away by the instrument/chip during carving

5. burnout phase: wax must burn completely and not leave a solid residue >0.10% of original weight of specimen

ideal properties of wax

flow

measure of the degree of permanent deformation of the material BELOW the melting temperature of the wax

relatively high flow

type i inlay wax must have ___, a few degrees about mouth temperature

37 C at 1%

type i inlay wax maximum flow to avoid distortion

45 is 70-90%

type i and ii inlay wax maximum flow

low flowing

ideal flow at working temperature

high flow

ideal flow to be able to record details

• melting range

• low thermal conductivity

• high coefficient of thermal expansion (expand → 0.7% every 20 C; contract → 0.35% when 37 C to 25 C) (type i has a high CTE)

thermal properties of wax

• weak intermolecular bonds

• low elastic modulus

mechanical properties of wax

• manipulation

• occluded air

• release of stress during cooling

• excessive storage time

• extreme temperature changes

• low CTE → outer layer cools first → core continues to contract

wax distortion can be caused by

elastic memory

waxes can return partially toward their ORIGINAL shape over time