waxes in dentistry

1. Dr. M. Pavan Preetham
Reader
Dept. of Prosthodontics
SB Patil Institute for Dental Sciences &
Research
Bidar
Dental waxes

2.  There are a variety of natural waxes and resins
that have been used in dentistry for specific and
well defined applications.
 Waxes are thermoplastic materials which are
solids at room temperature but melt without
decomposition to form mobile liquids

3. COMPONENTS OF DENTAL
WAXES
 Mineral Paraffin wax Distillation of crude petroleum
Straight chain hydrocarbon, Polycrystalline Brittle at
ambient temperature Microcrystalline / ceresin
Distillation of crude petroleum Branched chain
hydrocarbon, polycrystalline Less brittle than paraffin
due to their oil content
 Insect Bees wax Honeycombs Less crystalline than
paraffin wax, more amorphous When with paraffin
wax: -at room temp. makes it less brittle -at high temp
(e.g. mouth temp) reduces the flow of wax
 Vegetable Carnuaba wax South America palm tree -
Hard, lustrous, tough wax. Blended with paraffin to
harden it and raise it’s solid -solid transition
temperature
 Candella wax Plants - Same as above Resins and
gums Trees - Used to add adhesive qualities to wax

4. THERMAL PROPERTIES OF
WAXES
 MELTING RANGE • Waxes have a melting range
rather than a melting point.
 • Example : paraffin 44 – 62 C⁰ carnauba 50 – 90
C⁰
 • Significance: Mixing of waxes can change their
melting range.

5.  Solid-Solid transition temperature: (Tg)
Temperature at which a sharp increase in
coefficient of thermal expansion occurs indicating
increased molecular mobility.Also called softening
temperature or glass transition temperature.
 In waxes, at this temperature, transition from a
stable crystal lattice (orthorhombic) to hexagonal
form occurs which is present below the melting
point of wax and thus it allows the wax to be
manipulated easily without flaking or tearing. Wax
is soft (not melted) at this temperature.

6. COEFFICIENT OF THERMAL
EXPANSION
 Waxes expand when there is increase in
temperature and contract when there is decrease
in temp.
 Dental waxes have the greatest co-efficient of
thermal expansion than any other restorative
materials in dentistry . Value: 350x10-6/˚C
 Eg : CTE of type 1 wax is[ between 22C⁰ and
37.5C ⁰] is 323 10-6 FLOW
 Is the slippage of wax molecules over each other.

7.  This will cause the wax to expand n heating and
appreciably shrink on cooling from solidification
temp to room temp. On heating, may expand
0.7% when temp is increased 20 ˚C On cooling
from 37˚C to 25 ˚C , a linear shrinkage of 0.35%
occurs May cause distortion of wax patterns

8. Melting range
 Because waxes may contain several types of
molecules, each having a range of molecular
weights, they have melting ranges rather than
melting points Paraffin: 40-70 ˚C Microcrystalline:
60-90 ˚C Bees wax: 65-70 ˚C
 Thermal conductivity: Low thermal conductivity

9. MECHANICAL PROPERTIES
 Compressive strength , proportional limit, elastic
modulus of waxes are low.
 These properties strongly depends on the
temperature As the temp decreases mechanical
properties improve

10. Types
 Inlay wax
 Casting wax
 Base plate wax
 Wax rim
 Shellac denture base
 PROCESSING WAX: 1. Sticky wax 2. Utility wax
3. Block-out wax 4. Boxing & beading wax
 IMPRESSION WAX: 1. Corrective wax 2. Bite
registration

11. Inlay wax
 Classification(ADA Sp. No. 4)
 It is a type of pattern wax. Type I: Medium wax
employed in direct technique. Type II: Soft wax
used for indirect technique for inlays and crowns.
 Uses of inlay wax: 1. It is used to make patterns
for metallic restorations. 2. Patterns for inlays, 3.
crowns and bridges is first made in wax and then
converted into metal or ceramic by casting.

12. Casting wax
 It is a type of pattern wax.
 Classification (According to FDI Specification No.
140).
Class I : 28 gauge, pink ,Flow of about 10 % at
35C˚ Easily adaptable at 40 to 45C˚
Class II :30 gauge, green ,Minimum flow of 60 %
at 38C˚ ,adapts well to the surface ,not brittle on
cooling
Class III: readymade shapes, blue Will burnout at
500C˚ leaving no carbon residue ,Supplied As
Sheets 0.40 and 0.32 mm thickness.
• Used to produce the metallic component of partial
denture on the cast.

13.  COMPOSITION: Paraffin wax: 60% Carnuaba
wax: 20% Ceresin wax: 10% Bees wax: 5% Gum
Dammar: 5%

14. Base Plate Wax
 Classification (ADA Sp. No. 24)
 It is a type of pattern wax.
 Uses: used mainly in preparing wax patterns for
prosthesis.
 Supplied as : Sheets of pink or red color.

15. Wax rim (bite rim)
 It is a type of pattern wax.
 The softening temp. is above the mouth temp.
 It is tough & resist fracture during removal from
the cast.
 It used for : 1. Restoring the occlusal relationship.
2. Arrangement of teeth. 3. Check the
denture inside the patient mouth. Bite blockBite
stick

16.  COMPOSITION: Paraffin wax: 70-80% Bees wax:
12% Carnuaba wax: 2.5% Resins: 3% Synthetic
waxes: 2.5% METLING RANGE: 44 ˚C-62 ˚C

17. Shellac denture base
 It is a type of pattern wax
 Wax like resin stable at mouth temp.
 It has high softening temperature than other
waxes.
 It is used as a temporary denture base.

18. Sticky wax
 It is a type of processing wax.
 It is sticky when melted, with a max 5 %flow at 30
Cº and 90 % at 43 Cº .
 It adheres closely to the surfaces when applied to
it.
 If movement occurs the wax tends to fracture
than distort.
 At room temperature the wax is brittle and breaks
easily
 Uses: 1. It is used to align fractured parts of
acrylic dentures . 2. It is used to align fixed partial
denture units before soldering . 3. It is used to

19. Utility Wax
 It is a type of processing wax .
 Supplied as : It is available in the form of sticks
and sheets. Orange or dark red in color. In
orthodontics, periphery wax is white in color
 Flow at 37.5Cº- min. 65 % and max. 80%
 Pliable and tacky at 21-24Cº
 Uses: It can be used to alter the stock tray
extensions . The following alterations : 1. can be
made Height of the tray .

20. Boxing & beading waxes
 It is a type of processing wax.
 Use: • Beading wax is adapted around the
impression borders to create the land area of the
cast • Boxing wax is used to build up vertical
walls around the impression in order to pour the
gypsum product to make a cast base.
 Supplied as : • Boxing wax as sheets. • beading
wax as strips.

21. Block out wax
 It is a type of processing wax.
 Used for filling the undercut area on the cast
during processing of the Cr-Co frame work.

22. Impression waxes
 Corrective wax : • Wax in combination with resins
of low melting point can be used in corrective
impression technique in partial and complete
denture prosthesis. • The peculiarity of
impression wax is that they flow at mouth
temperature.
 Availability : sheets or cakes
 Used to restore the selected region in the
edentulous patients to reproduce the details of
mucous membrane.

23. Bite registration wax
 It is used to record the relationship of the upper &
lower teeth in dentulous patients