Se ha denunciado esta presentación.
Utilizamos tu perfil de LinkedIn y tus datos de actividad para personalizar los anuncios y mostrarte publicidad más relevante. Puedes cambiar tus preferencias de publicidad en cualquier momento.
Dr. Kriti Trehan
MDS 1ST Year
 Introduction
 History
 Classification
 Composition
 Desirable properties
 Types of inlay wax
 Flow
 Thermal prope...
 Variety of natural waxes and resins have been used in dentistry
for specific and well defined applications.
 Dental wax...
 Wax has been a valuable commodity for over 2000 years. In
ancient times beeswax was used which was derived from
secretio...
 The wide variety of dental waxes can be classified into
two groups, those used primarily in the clinic and those
used in...
Waxes
Pattern Processing Impression
1. Inlay
2. Casting
3. Baseplate
1. Boxing
2. Utility
3. Sticky
1. Occlusal
registrati...
PATTERN WAXES
 Used to form general pre determined size & contour of an
artificial restoration.
 Later it is replaced by...
 The dental waxes may be composed of natural waxes and
synthetic waxes, gums, fats, fatty acids, oils.
 Natural waxes ar...
Components of
dental Waxes
Natural
waxes
Synthetic
waxes Additives
1. Mineral
2. Plant
3. Insect
4. Animal
1. Polyethelene...
 Most dental waxes contain 40% to 60% paraffin by
weight, which is derived from high-boiling fractions of
petroleum.
 Th...
 Paraffin wax is likely to flake when it is trimmed, and it does
not produce a smooth, glossy surface, which is a desirab...
 Carnauba wax occurs as a fine powder on the leaves of
certain tropical palms. This wax is very hard, and it has a
relati...
 Ceresin is typically a white wax extracted from ozokerite, a waxy
mineral mixture of hydrocarbons that is colorless or w...
MELTING RANGE
•Waxes have a melting range rather than a melting point.
• Example : paraffin 44 – 62 C⁰ , carnauba 50 – 90 ...
MECHANICAL PROPERTIES
•Compressive strength , proportional limit, elastic modulus of
waxes are low.
•These properties stro...
1. The wax should be uniform when softened..
2. The color should contrast with die materials or prepared
teeth.
3. The wax...
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%...
 Inlay waxes are used to prepare patterns.
 Type I is a medium wax employed in
direct techniques and type II is a soft w...
 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
thei...
 A regular or soft type of wax is typically used for indirect work
at room temperature or in cool weather. A harder or me...
 A pattern made by the indirect method may
not shrink as much.
 DIRECT TECHNIQUE: A wax pattern made
in the mouth for pr...
 The first procedure in the casting of an inlay or crown for the lost-
wax process is the preparation of a dental wax pat...
 After investing
anatomically accurate
wax or resin patterns
for inlays, onlays,
crowns, bridges, and
frameworks for
remo...
 One of the desirable
properties of type I inlay
wax is that it should exhibit
a marked plasticity or flow
at a temperatu...
 Different types of casting waxes exhibit characteristic flow
curves as a function of temperature.
 Each wax exhibits a ...
 Requirements for the flow properties of inlay waxes at
specific temperatures are
 The maximum flow permitted for type I...
 The thermal conductivity of
the waxes is low (e.g.,
kparaffin = 0.25 W/mK), and
sufficient time must be
allowed both to ...
 The average linear thermal expansion coefficient over this
temperature range is 350 × 10−6 /K, with values ranging
from ...
 Waxes oxidize on heating, and on prolonged heating some
waxes evaporate, so that the storage container for melted
wax wi...
 To avoid distortion during removal of the pattern, it should be
penetrated slightly with an explorer point and carefully...
 The prepared cavity should be overfilled, and the wax then
carved to the proper contour.
 A silk or other fine cloth ma...
 Distortion of a wax pattern results from occluded air in the
pattern, physical deformation (during molding, carving, or
...
 To demonstrate this effect, a stick of inlay wax can be softened
over a Bunsen burner, bent into a horseshoe shape, and
...
 Storage of a wax pattern for too long can lead to a distortion
of its form because of stress relaxation effects.
 A cas...
1. Baseplate wax is used to establish the initial arch form in the
construction of complete dentures.
 Supplied in 1- to ...
 The harder the wax, the less the flow at a given temperature.
The difference in flow of the three types may be
advantage...
 USES:
To establish vertical dimension ,plane of occlusion,and
initial arch form in the technique for the complete dentu...
2. Casting wax
 The pattern for the metallic framework of removable partial
dentures and other similar structures is fabr...
 Classification (According to FDI Specification No. 140):
Class I : 28 gauge, pink ,Flow of about 10 % at 35C˚
Easily ad...
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...
 Uses:
 It is used to align fractured parts of acrylic
dentures .
 It is used to align fixed partial denture units
befo...
4. Utility wax
 It is a type of processing wax .
 Supplied :in the form of sticks
and sheets. Orange or dark red
in colo...
 A standard perforated tray for use with hydrocolloids may
easily be brought to a more desirable contour by utility
wax.
...
5. Boxing & beading waxes:
 It is a type of processing wax.
 Supplied as :
#Boxing wax as sheets. #Beading wax as strips.
 Use:
 Beading wax is adapted
around the impression borders
to create the land area of the
cast.
a cast base.
 Boxing ...
6. Impression waxes:
a) Corrective wax : Wax in combination with resins of low
melting point can be used in corrective imp...
b) Bite registration wax : It is used to record the relationship
of the upper & lower teeth in dentulous patients .
• Wax ...
Methods of softening wax
1. Water Bath 2. Flame of Bunsen burner
3.Infrared lamp 4. Wax annealer
A study was conducted by Rajagopal P1, Chitre V, Aras MA to
compare the accuracy of patterns processed from an inlay
casti...
 The results revealed that the inlay wax showed a significantly
greater marginal discrepancy at the 12 and 24 h intervals...
Iglesias A, Powers JM, Pierpont HP conducted a study on the
marginal fit of MOD inlay and full-crown patterns fabricated f...
 Gaps were measured with a measuring microscope in four
marginal areas on the master dies at 1 and 24 hours after
fabrica...
A study was done to compare marginal and internal fit of
pressed ceramic crowns made from conventional and
computer-aided ...
 CAD/CAM wax manufacturing significantly decreased the
marginal gap when compared with conventional waxing.
 CAD/CAM wax...
Recent advances
 Conventionally, wax patterns were fabricated with wax and
waxing instruments for example the popular PKT...
 Because of the wax pattern’s color and glossy surface, small
defects can be difficult to identity.
 Zeltser et al. foun...
 Using CAD/ CAM systems have many advantages such as
producing higher and more uniform-quality restorations by using
comm...
 The point clouds obtained in scanning are transformed
through a CAD software algorithm into a smooth and
continuous surf...
1. Anusavice K.J.-“Phillips’ Science of Dental materials” 11th
edition , 2003.Pg 283-292.
2. Craig’s R.G. Powers J.M. – “R...
5. M Vojdani,a K Torabi,a E Farjood,b and AAR Khaledia.
Comparison the Marginal and Internal Fit of Metal Copings
Cast fro...
Ha terminado este documento.
Descárguela y léala sin conexión.
Próximo SlideShare
What to Upload to SlideShare
Siguiente
Próximo SlideShare
What to Upload to SlideShare
Siguiente
Descargar para leer sin conexión y ver en pantalla completa.

Compartir

Dental waxes final ppt

Descargar para leer sin conexión

INLAY WAX IN DETAIL

Audiolibros relacionados

Gratis con una prueba de 30 días de Scribd

Ver todo

Dental waxes final ppt

  1. 1. Dr. Kriti Trehan MDS 1ST Year
  2. 2.  Introduction  History  Classification  Composition  Desirable properties  Types of inlay wax  Flow  Thermal properties  Wax distortion  Manipulation  Other dental waxes  Recent advances  References
  3. 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. 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. 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. 6. Waxes Pattern Processing Impression 1. Inlay 2. Casting 3. Baseplate 1. Boxing 2. Utility 3. Sticky 1. Occlusal registration 2. Corrective
  7. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 41.  Uses:  It is used to align fractured parts of acrylic dentures .  It is used to align fixed partial denture units before soldering.
  42. 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. 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. 44. 5. Boxing & beading waxes:  It is a type of processing wax.  Supplied as : #Boxing wax as sheets. #Beading wax as strips.
  45. 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. 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. 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. 48. Methods of softening wax 1. Water Bath 2. Flame of Bunsen burner 3.Infrared lamp 4. Wax annealer
  49. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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.
  • VandanaSingh314

    Oct. 6, 2021
  • alikaiss

    Oct. 4, 2021
  • MohanRavi8

    Sep. 21, 2021
  • SwatiKanaujia

    Jul. 16, 2021
  • BipashaKumar2

    Jul. 10, 2021
  • JoChiira

    Jul. 7, 2021
  • bharathkumar1626

    Jul. 3, 2021
  • BanpreetKaur5

    Jul. 2, 2021
  • RajmeetaDash

    Jun. 28, 2021
  • RukhsarRizwan

    Jun. 17, 2021
  • SrilakshmiRathinavel

    Jun. 14, 2021
  • RomaSingh9

    Jun. 13, 2021
  • kirtikomal1

    Jun. 9, 2021
  • RadhaNarlawar

    May. 2, 2021
  • JoyshreeSinha

    Apr. 28, 2021
  • GayatriBobde

    Apr. 21, 2021
  • AmirKassim3

    Apr. 16, 2021
  • YashaswiniMukunda

    Mar. 26, 2021
  • JSaiRam1

    Mar. 24, 2021
  • Gabyfenzy

    Mar. 6, 2021

INLAY WAX IN DETAIL

Vistas

Total de vistas

31.624

En Slideshare

0

De embebidos

0

Número de embebidos

47

Acciones

Descargas

725

Compartidos

0

Comentarios

0

Me gusta

100

×