INLAY WAX IN DETAIL

1. Dr. Kriti Trehan
MDS 1ST Year

2.  Introduction
 History
 Classification
 Composition
 Desirable properties
 Types of inlay wax
 Flow
 Thermal properties
 Wax distortion
 Manipulation
 Other dental waxes
 Recent advances
 References

3.  Variety of natural waxes and resins have been used in dentistry
for specific and well defined applications.
 Dental waxes :A low-molecular-weight ester of fatty acids
derived from natural or synthetic components, such as petroleum
derivatives, that soften to a plastic state at a relatively low
temperature.
 They consist of two components
which may be natural or synthetic
waxes, resins, oils and pigments.

4.  Wax has been a valuable commodity for over 2000 years. In
ancient times beeswax was used which was derived from
secretions that bees use to build honeycombs.
 First inlay in dentistry is credited to JOHN MURPHY of london
who was fabricting porcelain inlay in 1855.
 First cast inlay is attributed to PHILBROOK in 1897.
 TAGGART in 1907 introduced lost wax technique

5.  The wide variety of dental waxes can be classified into
two groups, those used primarily in the clinic and those
used in commercial dental laboratories.
Clinical Laboratory
1. Bite registration
2. Disclosing
3. Type I inlay
1. Boxing
2. Baseplate
3. Sticky
4. Beading
5. Utility
6. Hard, medium,
and soft type II
inlay-type waxes

6. Waxes
Pattern Processing Impression
1. Inlay
2. Casting
3. Baseplate
1. Boxing
2. Utility
3. Sticky
1. Occlusal
registration
2. Corrective

7. PATTERN WAXES
 Used to form general pre determined size & contour of an
artificial restoration.
 Later it is replaced by more durable material such as cast
gold, cobalt- chrome- nickel alloys etc.
 They exhibit thermal change in dimension and warpage on
standing.
PROCESSING WAXES
 Used primarily as auxillary aids in constructing variety of
restorations and appliances.
IMPRESSION WAXES
 Impression waxes, though rarely used to record
complete impressions, they can be effectively used to correct
small imperfections in other impressions.

8.  The dental waxes may be composed of natural waxes and
synthetic waxes, gums, fats, fatty acids, oils.
 Natural waxes are derived from mineral, vegetable, and animal
origins.
 Synthetic waxes are chemically synthesized from natural wax
molecules and are typically composed of hydrogen, carbon,
oxygen, and chlorine.
 Coloring agents are added for contrast of wax patterns against
tooth, die, and model surfaces.
 Some formulations contain a compatible filler to control
expansion and shrinkage of the wax product.

9. Components of
dental Waxes
Natural
waxes
Synthetic
waxes Additives
1. Mineral
2. Plant
3. Insect
4. Animal
1. Polyethelene
2. Polyoxyethelen
e
3. Hydrogenated
1. Oils
2. Colors
3. Fats
4. Natural
resins
5. Synthetic
resins

10.  Most dental waxes contain 40% to 60% paraffin by
weight, which is derived from high-boiling fractions of
petroleum.
 They are composed mainly of a complex mixture of
hydrocarbons of the methane series together with minor
amounts of amorphous and microcrystalline phases.
 The melting temperature generally increases with
increasing molecular weight.
 This condition promotes moldability of the wax below its
melting temperature.

11.  Paraffin wax is likely to flake when it is trimmed, and it does
not produce a smooth, glossy surface, which is a desirable
requisite for an inlay wax.
 Gum dammar, or dammar resin, is a natural resin. It is
added to the paraffin to improve the smoothness in molding
and to render it more resistant to cracking and flaking.
 It also increases the toughness of the wax and enhances
the smoothness and luster of the surface.

12.  Carnauba wax occurs as a fine powder on the leaves of
certain tropical palms. This wax is very hard, and it has a
relatively high melting point and it has an agreeable odor.
 It is combined with the paraffin to decrease flow at mouth
temperature. Carnauba wax contributes greater
glossiness to the wax surface than dammar resin.
 Candelilla wax can also be added partially or entirely to
replace carnauba wax. Candelilla wax provides the same
general qualities as carnauba wax but its melting point is
lower and it is not as hard as carnauba wax.

13.  Ceresin is typically a white wax extracted from ozokerite, a waxy
mineral mixture of hydrocarbons that is colorless or white when
pure, but it has a somewhat unpleasant odor.
 They may be used to increase the melting range of paraffin waxes.
 Carnauba wax is often replaced in part by certain synthetic waxes
that are compatible with paraffin wax.
 One is montan wax, a derivative hard wax that is obtained by
solvent extraction of certain types of lignite or brown coal.
 Montan waxes are hard, brittle and lustrous; they blend with other
waxes and therefore often substituted to increase the melting range
of paraffin waxes.

14. 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.
COEFFICIENT OF THERMAL EXPANSION
• Waxes expand when there is increase in temperature and
contract when there is decrease in temperture.
•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.
•Dental waxes have the greatest co-efficient of thermal
expansion than any other restorative materials in dentistry .

15. MECHANICAL PROPERTIES
•Compressive strength , proportional limit, elastic modulus of
waxes are low.
•These properties strongly depends on the temperature.
FLOW
•The property of flow results from the slippage of molecules
over each other.
•Waxes show deformation when subjected to constant load for
a period of time. Amount of flow depends upon:
 temperature of the wax
the force bringing about the deformation
 the time the force is applied

16. 1. The wax should be uniform when softened..
2. The color should contrast with die materials or prepared
teeth.
3. The wax should not fragment into flakes or similar
surface particles when it is molded after softening.
4. The wax must not be pulled away by the carving
instrument or chip as it is carved or such precision
cannot be achieved.

17. 5. Ideally, when wax melts and is vaporized at 500 °C, it
should not leave a solid residue that amounts to more
than 0.10% of the original weight of the specimen.
6. The wax pattern should be completely rigid and
dimensionally stable at all times until it is eliminated.
 Expansion and shrinkage of casting wax are extremely
sensitive to temperature.
 Normally soft wax shrinks more than hard wax. High-
shrinkage wax may cause significant pattern distortion
when it solidifies..

18.  Inlay waxes are used to prepare patterns.
 Type I is a medium wax employed in
direct techniques and type II is a soft wax
used in the indirect techniques.
 Inlay wax must exhibit excellent
adaptability to model or die surfaces, and
it must be free from distortion, flaking, or
chipping during the preparation of
patterns.

19.  Inlay waxes may be softened over a
flame or in water at 54 °C to 60 °C to
enable their flow in the liquid state and
their adaptation to the prepared tooth
or die.
 For direct wax techniques type I inlay
wax must soften at a temperature that
is not hazardous to the pulp tissue, and
it must harden at a temperature above
mouth temperature.
 These waxes are designed to maintain
uniform workability over a wide
temperature range and to facilitate
accurate adaptation to the tooth or die
under pressure.

20.  A regular or soft type of wax is typically used for indirect work
at room temperature or in cool weather. A harder or medium
type with a low flow property is indicated for use in warmer
climates.
 INDIRECT TECHNIQUE : The cavity is prepared in the tooth
and the pattern is carved directly on a die that is a
reproduction of the prepared tooth and dental tissues.

21.  A pattern made by the indirect method may
not shrink as much.
 DIRECT TECHNIQUE: A wax pattern made
in the mouth for producing wax inlay
patterns within prepared teeth .
 Because the thermal expansion coefficient
of wax is extremely high compared with the
values for other dental materials, a wax
pattern made in the mouth (direct
technique) will shrink appreciably as it is
cooled to room temperature.

22.  The first procedure in the casting of an inlay or crown for the lost-
wax process is the preparation of a dental wax pattern by direct or
indirect wax technique.
 The wax pattern forms the outline of the mold into which an alloy is
cast or a ceramic is hot-isostatically pressed.
 The pattern should be well adapted to the prepared cavity or replica
cavity and properly carved without any significant distortion.
 Before the adaptation of the wax pattern within a tooth or a die, a
separating medium must be used.
 After the pattern is removed from the prepared cavity, it is encased
in a gypsum or phosphate-based refractory material known as an
investment which is called investing the pattern.

23.  After investing
anatomically accurate
wax or resin patterns
for inlays, onlays,
crowns, bridges, and
frameworks for
removable partial
dentures, the invested
material must be
eliminated completely
before molten metal is
cast or core ceramic is
hot-pressed into the
mold cavity.

24.  One of the desirable
properties of type I inlay
wax is that it should exhibit
a marked plasticity or flow
at a temperature slightly
above that of the mouth.
 The temperatures at which
the wax is plastic are
indicated by the time-
temperature cooling curve
for a typical type I wax.
FLOW OF INLAY WAX

25.  Different types of casting waxes exhibit characteristic flow
curves as a function of temperature.
 Each wax exhibits a sharp transition temperature at which it
loses its plasticity.
 Soft wax exhibits a transition point at a lower temperature
than hard wax.
 Inlay waxes do not solidify with a space lattice, as does a
metal. Instead, the structure likely exhibits a combination of
crystalline and amorphous structures.
 The wax lacks rigidity and may flow under applied pressure
even at room temperature

26.  Requirements for the flow properties of inlay waxes at
specific temperatures are
 The maximum flow permitted for type I waxes at 37 °C is 1%.
 Their low flow at this temperature permits carving and
removal of the pattern from the prepared cavity at oral
temperature without distortion.
 In addition, both type I and type II waxes at 45 °C must have
a minimal flow of 70% and a maximum flow of 90%.

27.  The thermal conductivity of
the waxes is low (e.g.,
kparaffin = 0.25 W/mK), and
sufficient time must be
allowed both to heat them
uniformly throughout and to
cool them to body or room
temperature.
 Another thermal characteristic
of inlay waxes is their high
coefficient of thermal
expansion.

28.  The average linear thermal expansion coefficient over this
temperature range is 350 × 10−6 /K, with values ranging
from 217 to 512 × 10−6 /K.
 Curve A represents the thermal expansion of inlay wax as
a function of temperature. The expansion rate increases
abruptly above approximately 35 °C.
 The temperature at which a change in rate occurs is known
as the glass transition temperature.
 Some constituents of the wax probably change in their
crystalline form at this temperature, and the wax is more
plastic at higher temperatures.

29.  Waxes oxidize on heating, and on prolonged heating some
waxes evaporate, so that the storage container for melted
wax will be coated by gummy deposits.
 Therefore, care should be exercised to use the lowest
temperature possible and to clean the wax pot and replace
the wax periodically.
 To manipulate inlay wax, dry heat is preferred to the use of a
water bath.
 The latter can result in the inclusion of droplets of water,
which can splatter on flaming, smear the wax surface during
polishing, and distort the pattern during temperature
changes.

30.  To avoid distortion during removal of the pattern, it should be
penetrated slightly with an explorer point and carefully removed
from the cavity.
 After removal, touching the pattern with the fingers should be
avoided as much as possible to prevent any temperature
changes and distortion.
 To fabricate indirect patterns, the die should be lubricated,
preferably with a lubricant containing a wetting agent.
 Any excess must be avoided because it will prevent intimate
adaptation to the die.
 The melted wax may be added in layers with a spatula or a
waxing instrument.

31.  The prepared cavity should be overfilled, and the wax then
carved to the proper contour.
 A silk or other fine cloth may be used for a final polishing of the
pattern, rubbing toward the margins.
 Some clinicians prefer to apply finger pressure as the wax is
cooling to help fill the cavity and prevent distortion during
cooling. The fingers also accelerate the cooling rate.
 Regardless of the method chosen, the most practical method for
avoiding any possible delayed distortion is to invest the pattern
immediately after removal from the mouth or die.
 Once the investment hardens (sets), no distortion of the pattern
will occur.

32.  Distortion of a wax pattern results from occluded air in the
pattern, physical deformation (during molding, carving, or
removal), release of stresses “trapped” during previous
cooling, excessive storage time, and extreme temperature
changes during storage.
 It is important that the wax pattern be retained on the die for
several hours to avoid distortion and ensure that equilibrium
conditions are established.
 Waxes tend to return partially to their original shape after
manipulation. This is known as elastic memory.

33.  To demonstrate this effect, a stick of inlay wax can be softened
over a Bunsen burner, bent into a horseshoe shape, and
chilled in this position.
 If it is then floated in room-temperature water for a number of
hours, the horseshoe will open, A and B.
 When the wax is bent into a horseshoe, the inner molecules
are under compression and the outer ones are in tension.
 Once the stresses are gradually relieved at room temperature,
the wax tends to recover its elastic strain.

34.  Storage of a wax pattern for too long can lead to a distortion
of its form because of stress relaxation effects.
 A casting will fit most accurately when the pattern is
invested immediately after its removal from the preparation.

35. 1. Baseplate wax is used to establish the initial arch form in the
construction of complete dentures.
 Supplied in 1- to 2-mm-thick red or pink sheets.
 COMPOSITION:
oParaffin wax: 70-80%
oBees wax: 12%
o Carnuaba wax: 2.5%
oResins: 3%
oSynthetic waxes: 2.5%


36.  The harder the wax, the less the flow at a given temperature.
The difference in flow of the three types may be
advantageous for a particular application.
 Type I, a soft wax, is used for building veneers.
 Type II, a medium wax, is designed for patterns to be
placed in the mouth in normal climatic conditions.
 Type III, a hard wax, is used for trial fitting in the mouth in
tropical climates

37.  USES:
To establish vertical dimension ,plane of occlusion,and
initial arch form in the technique for the complete denture
restoration.
 To form all or a portion of tray itself.
Used to produce desired contour of the denture after
teeth are set in position.

38. 2. Casting wax
 The pattern for the metallic framework of removable partial
dentures and other similar structures is fabricated from
casting waxes.
 These waxes are available in the form of sheets, usually of
28- and 30-gauge (0.40 and 0.32 mm) thickness, ready-
made shapes, and in bulk.

39.  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.
 Used to produce the metallic component of partial
denture on the cast.

40. 3. 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
and 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
firm,free from tackiness and brittle.

41.  Uses:
 It is used to align fractured parts of acrylic
dentures .
 It is used to align fixed partial denture units
before soldering.

42. 4. Utility wax
 It is a type of processing wax .
 Supplied :in the form of sticks
and sheets. Orange or dark red
in color.
 Flow at 37.5Cº- min. 65 % and
max. 80% .
 Pliable and tacky at 21-24Cº.

43.  A standard perforated tray for use with hydrocolloids may
easily be brought to a more desirable contour by utility
wax.
 It can be used to alter the stock tray extensions.

44. 5. Boxing & beading waxes:
 It is a type of processing wax.
 Supplied as :
#Boxing wax as sheets. #Beading wax as strips.

45.  Use:
 Beading wax is adapted
around the impression borders
to create the land area of the
cast.
a cast base.
 Boxing wax is used to build
up vertical walls around the
impression in order to pour the
gypsum product to make a cast
base.

46. 6. Impression waxes:
a) 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
 Uses:
 As a wax veneer over an original impression to contact
and register the details of the soft tissue.

47. b) Bite registration wax : It is used to record the relationship
of the upper & lower teeth in dentulous patients .
• Wax is softened under hot running water
• Full arch, quadrant or just a few teeth can be taken

48. Methods of softening wax
1. Water Bath 2. Flame of Bunsen burner
3.Infrared lamp 4. Wax annealer

49. A study was conducted by Rajagopal P1, Chitre V, Aras MA to
compare the accuracy of patterns processed from an inlay
casting wax, an auto-polymerized resin and a light-cured resin
pattern material.
 Ten patterns each were fabricated from an inlay casting wax
(GC Corp., Tokyo, Japan), an autopolymerized resin pattern
material (Pattern resin, GC Corp, Tokyo, Japan) and a light-
cured resin pattern material (Palavit GLC, Hereaus Kulzer
GmbH, Germany).
 The completed patterns were stored off the die at room
temperature.
 Marginal gaps were evaluated by reseating the patterns on
their respective dies and observing it under a
stereomicroscope at 1, 12, and 24 h intervals after pattern
fabrication.

50.  The results revealed that the inlay wax showed a significantly
greater marginal discrepancy at the 12 and 24 h intervals.
 The autopolymerized resin showed an initial (at 1 h) marginal
discrepancy slightly greater than inlay wax, but showed a
significantly less marginal gap (as compared to inlay wax) at the
other two time intervals.
 The light-cured resin proved to be significantly more dimensionally
stable, and showed minimal change during the storage period.
CONCLUSION:
 The resin pattern materials studied, undergo a significantly less
dimensional change than the inlay waxes on prolonged storage.
 They would possibly be a better alternative to inlay wax in situations
requiring high precision or when delayed investment (more than 1
h) of patterns can be expected.

51. Iglesias A, Powers JM, Pierpont HP conducted a study on the
marginal fit of MOD inlay and full-crown patterns fabricated from
wax, autopolymerized acrylic resin, and two light-polymerized,
diacrylate resin pattern materials compared on standardized dies.
 Four pattern materials were studied-
two light-polymerized,
diacrylate resin materials (Palavit G LC and Triad VLC Burnout
Paste),
an inlay wax,
an autopolymerized resin (Duralay).
 Patterns were fabricated using incremental and bulk
techniques on stone dies made from addition silicone
impressions MOD and full-crown master dies.

52.  Gaps were measured with a measuring microscope in four
marginal areas on the master dies at 1 and 24 hours after
fabrication.
 When measured on intra- and extracoronal master dies,
the light-polymerized, diacrylate resins had equal or better
marginal fit, compared with wax or autopolymerized acrylic
resin, and were less affected by placement technique and
storage.

53. A study was done to compare marginal and internal fit of
pressed ceramic crowns made from conventional and
computer-aided design and computer-aided manufacturing
wax patterns.
 Ten silicone impressions were made for a maxillary
canine prepared to receive a complete crown.
 Two pressed lithium disilicate glass ceramic copings were
made on the die poured from each impression. The first was
from a conventional wax pattern and the second from milled
wax blocks.
 The subtractive CAD-CAM waxing technique resulted in the
improved fit of a pressed lithium disilicate crown by decreasing
the marginal discrepancies and internal adaptation.

54.  CAD/CAM wax manufacturing significantly decreased the
marginal gap when compared with conventional waxing.
 CAD/CAM wax manufacturing significantly improved the
adaptation at the axial walls when compared with
conventional waxing.
 No significant difference was found between CAD/ CAM
and conventional wax manufacturing regarding the
adaptation of the occlusal surface.

55. Recent advances
 Conventionally, wax patterns were fabricated with wax and
waxing instruments for example the popular PKT instruments.
 Wax is used to make the patterns because it can be
conveniently manipulated, precisely shaped and can also be
completely eliminated from the mold by heating .
 The fabrication of the wax pattern is the most critical and
labor-intensive step in making the porcelain fused-metal
crown. In this time-consuming task, the wax–up’s quality is
dependent on the skilled labor of the individual.

56.  Because of the wax pattern’s color and glossy surface, small
defects can be difficult to identity.
 Zeltser et al. found that the act of removing a wax pattern
from a die with a shoulder margin causes an average of
35μm opening of the margin before investing.
 Wax has several inherent limitations namely, delicacy,
thermal sensitivity, elastic memory and a high coefficient of
thermal expansion (CTE).
 Today, by introducing different CAD/CAM systems, it is
possible to fabricate the wax patterns made from castable
materials and omit several limitation of conventional wax-up
technique.

57.  Using CAD/ CAM systems have many advantages such as
producing higher and more uniform-quality restorations by using
commercially formed blocks of material, standardizing
restoration shaping processes and reducing production costs,
labor and time .
 Another advantage is the potential to enhance accuracy as they
omit several fabrication steps used as waxing, investing and
casting.
 CAD/CAM systems also have some disadvantages, the
scanning systems have the limitation of finite resolution, which
can result in edges that are slightly rounded.

58.  The point clouds obtained in scanning are transformed
through a CAD software algorithm into a smooth and
continuous surface, which can also lead to some internal
inaccuracies. This can lead to interfering contacts at the
incisal/occlusal edges and can be detrimental if they occur
at the margins
 Although CAD/CAM technology has already changed
dentistry, it needs some improvement in scanning
procedure, data processing, manufacturing techniques and
material processing to be a competitive alternative for
conventional method of fabrications.

59. 1. Anusavice K.J.-“Phillips’ Science of Dental materials” 11th
edition , 2003.Pg 283-292.
2. Craig’s R.G. Powers J.M. – “Restorative Dental Materials”
12thedition,2006.Pg 338-355.
3.Rajagopal P1, Chitre V, Aras MA.A comparison of the
accuracy of patterns processed from an inlay casting wax,
an auto-polymerized resin and a light-cured resin pattern
material. Indian J Dent Res.2012 Mar-Apr;23(2):152-6.
4. Iglesias A1, Powers JM, Pierpont HP. Accuracy of wax,
autopolymerized, and light-polymerized resin pattern
materials.J Prosthodont. 1996 Sep;5(3):201-5.

60. 5. M Vojdani,a K Torabi,a E Farjood,b and AAR Khaledia.
Comparison the Marginal and Internal Fit of Metal Copings
Cast from Wax Patterns Fabricated by CAD/CAM and
Conventional Wax up Techniques. J Dent (Shiraz). 2013 Sep;
14(3): 118–129.
6. Shamseddine L, Mortada R, Rifai K, Chidiac JJ.Marginal
and internal fit of pressed ceramic crowns made from
conventional and computer-aided design and computer-aided
manufacturing wax patterns: An in vitro comparison. J
Prosthet Dent. 2016 Aug;116(2):242-8.