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Waxes in dentistry

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This presentation describes about all kind of waxes used in dentistry, their composition, properties, indication, advantages and disadvantages.

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Waxes in dentistry

  1. 1. WAXES IN DENTISTRY Presented By : Arpit Viradiya Guided By : Dr. Ashutosh Paliwal Dr. Sandeep Metgud
  2. 2. Contents • Introduction • Waxes • Gums • Fats • Resins • Characteristics properties of waxes – Melting Range – Thermal Expansion – Mechanical Properties – Flow – Residual Stress – Ductility
  3. 3. • Dental Waxes – Inlay Pattern Wax • Composition • Properties • Flow • Thermal Coefficient of Expansion • Warpage of Wax Patterns – Casting Wax • Physical characteristics
  4. 4. • Resin Modeling Material • Baseplate Wax – Composition – Physical Characteristics • Boxing Wax • Utility Wax • Sticky Wax • Carding Wax • Corrective Impression Wax • Occlusal (Bite) Registration Wax
  5. 5. Introduction • The word "wax" is derived from the old English "weax" for the honeycomb of the bee- hive. • Waxes have versatile role to play in dentistry, few procedures in restorative dentistry cannot be completed without the use of wax in one of its many forms.
  6. 6. History • The oldest wax used by people were the beeswax. • Over 60 million years ago, the insects wax production was already accepted by people as a diet source. • First inlay in dentistry is credited to “John murphy” of london,who was fabricating porcelain inlay in 1855.
  7. 7. • In 1880, Ames used a burnished-foil technique for fabrication of inlays. • First cast inlay is attributed to “philbrook”-1897 • “Taggart” in 1907 introduced lost wax technique. • First synthetic liquid paraffins were produced according to the Fischer-Trop’s procedure in 1935.
  8. 8. Definition • ACCORDING TO ANUSAVICE— • “A low molecular weight ester of fatty acids with monohydrate alcohol derived from natural and synthetic components such as petroleum derivatives that softens to a plastic state at a relatively low temperature “.
  9. 9. • Dental wax : A mixture of two or more waxes with other additives, used in dentistry for casts, construction of nonmetallic denture bases, registering of jaw relations, and laboratory work. – Dorland's Medical Dictionary for Health Consumers. © 2007 by Saunders, an imprint of Elsevier
  10. 10. Mineral Paraffin Microcrystalline BamsdahI Ozokerite CereSin Montan Plant Carnauba Ouricury Candelilla Japan wax Cocoa butter Insect Beeswax Animal Spermaceti Natural waxes Acrawax Aerosol-OT Castor wax Flexowax Epolene Albacer Aldo-33 Durawax Synthetic Waxes Stearic acid Glyceryl – Tistearate Oils Turpentine Colorants Natural resins Rosin copal dammar shellac Synthetic resins poly- -styrene Additives Restorative dental materials: CRAIG & POWERS
  11. 11. Waxes • Dental waxes may be composed of natural and synthetic waxes, gums, fats, fatty acids, oils, natural and synthetic resins, and pigments. • The particular working characteristics of each wax are achieved by blending the appropriate natural and synthetic waxes, resins and other additives.
  12. 12. • Natural waxes are distributed in nature whereas synthetic waxes are produced by combination of various chemicals in laboratory. • The additives may be natural minerals and synthetic products.
  13. 13. Natural Waxes • Mineral-Plant-Insect-Animal • The chief constituent of most of the mineral waxes are hydrocarbons Ranging 17 to 44 carbon atoms: CH3-(CH2)-CH3 15-42 • The hydrocarbons in the plant waxes are saturated alkanes with 19 to 31 carbon atoms present in odd numbers.
  14. 14. • Plant and animal waxes contain considerable concentration of esters • carnauba ( plant wax) contains 85% alkyl esters of various kinds. • The principle esters in beeswax is myricyl palmitate. – Which is the reaction product of myricyl alcohol and palmitic acid.
  15. 15. • This brief description about the composition of natural wax indicates that they are complex combinations of organic compounds of reasonably high molecular weights • Also composition of these waxes varies • So blending of particular batches of wax is necessary to obtain the desirable property.
  16. 16. Characteristics of each waxes • Paraffin wax: – Source :high boiling fractions of petroleum – Type :straight chain hydrocarbon with 26-30 carbon atoms – Melting range:40-71degrees – White ,transparent – Increasing molecular weight increases melting point
  17. 17. – Presence of oils in the wax will lower the melting point – Brittle at ambient temperatures – Crystallize in the form of plates, needles , malcrystals – During solidification & cooling there is volumetric contraction varying from 11-15% – In dentistry used as refined waxes & have <0.5% of oil
  18. 18. • Microcrystalline wax: – Source : also obtained from heavier oil fractions in petroleum industry – higher melting range :60-91 degrees – Type :branched chain hydrocarbon – Tougher & more flexible than paraffin – less volumetric change -paraffin. – Hardness and the tackiness can be altered by the additions of oils.
  19. 19. • Barnsdahl wax: – Is microcrystalline wax with melting range 70-74degrees – Paraffin: increases the • Melting range • Hardness • Decrease the Flow
  20. 20. • Ozokerite : – Earth wax found near petroleum deposits of central Europe and western united states – Has straight , closed and branched chain hydrocarbons – Melting range: 65degrees
  21. 21. • Has affinity for oil • Improves the physical properties of paraffin in melting range of 54 degrees when added in the amount of 5-15%
  22. 22. • Ceresin : – from natural –mineral petroleum refining and lignite refining. – Straight & branched chain paraffins – Higher molecular weight – Greater hardness than hydrocarbon waxes from crude products – Used to increase the melting range of paraffin waxes
  23. 23. • Montan wax: – are obtained from various lignite's – although they are mineral waxes their composition and properties are similar to the plant waxes – Melting range-72-920 C – Mixtures of Long Chain esters from 40 to 58 carbon atoms
  24. 24. – Are hard, brittle and lustrous – Blend well with other waxes. – Substituted for plant waxes for improving the hardness and melting range of paraffin waxes
  25. 25. • Carnauba & Ouricury waxes: – Straight chain esters, alcohols, acids, and hydrocarbons – High • Hardness • Brittleness • Melting temperatures – They improve the melting range and hardness of paraffin wax ; – raises solid- solid transition temperature – Melting range • Carnauba: 84-910 C • Ouricury :79-840 C
  26. 26. • Candelilla wax: – Contain 40-60% paraffin, free alcohols, acids, esters and lactones. – Melting range : 68-750 C – Like carnauba they harden the paraffin wax but are not effective for increasing the melting range.
  27. 27. • Japan wax & Cocoa butter: – Are not true waxes – Chiefly fats – Japan wax: • contains the glycerides of palmitic and stearic acid. • Tough, malleable and sticky. • Is mixed with paraffin to improve tackiness and emulsifying ability • Melting range: 510 C
  28. 28. – Cocoa butter: • Contains glycerides of palmitic, stearic, oleic, lauric and lower fatty acids. • Is brittle at room temperature. • Is primarily used to protect the soft tissues against dehydration and also to protect the glass ionomer from moisture during setting or to protect them from dehydrating after they are set.
  29. 29. • Bees wax: – Insect wax – Is a complex mixture of esters – Melting temperature of 63-700 C. – Brittle at room temperature but becomes plastic at body temperature. – Modifies properties of paraffin wax – Main component of sticky wax.
  30. 30. • Spermaceti wax: – Obtained from sperm whale – Mainly ester waxes – Used as a coating in the manufacture of dental floss
  31. 31. Synthetic waxes • Are complex organic compounds of varied chemical composition • Differ from natural wax as they have a high degree of refinement in contrast to contamination seen in natural waxes • Include – Polyethylene waxes – Polyoxyethylene glycol waxes – Halogenated hydrocarbon waxes – Hydrogenated waxes
  32. 32. • Polyethylene polymers – Molecular weight: 2000-4000 – Melting range: 100-1050 C – Properties similar to high molecular weight paraffin • Polyoxyethylene polymers – Polymer of ethylene glycol – Melting range :37-630 C – Limited compatibility with other wax – Function as plasticizers – Toughen films of wax
  33. 33. Gums • Many waxes obtained from plants and animals resemble in appearance to group of substances described as gums. • Most gums are complicated substances, and when mixed with water they either dissolve or form sticky, viscous liquids. • Gum arabic and tragacanth are two natural gums that do not resemble waxes in either their properties or composition.
  34. 34. Fats • Chemically fats are composed of esters of various fatty acids with glycerol and are known as glycerides, which distinguishes them from waxes. • Both wax and fats are tasteless colorless and odorless in their pure form and feel greasy to touch. • The fat may be used to increase the melting range and hardness of compounded wax
  35. 35. Resins • Most of the resin are from plants and trees except for shellac (insects) • Natural resins such as dammar and kauri when mixed with wax produce harder products • Synthetic resins are added to paraffin waxes to improve their: toughness, film forming character , melting range
  36. 36. Characteristic properties of waxes • Melting range: – Waxes consist of several types of molecules , each having a range of molecular weights – Hence they have melting ranges rather than melting points – M.R. of paraffin:44-620C – M.R. of carnauba:50-900C
  37. 37. Thermal expansion • Expand when temp. is risen • Contract when temp. is decreased • Dental waxes have the largest coefficient of thermal expansion. • Temp. change in wax patterns may be a major contributing factor in inaccuracy of the finished restoration • Many waxes exhibit at least two rates of expansion between 22-520 C
  38. 38. Mechanical properties • The elastic modulus • Proportional limit and • Compressive strength of waxes are low compare with those of other materials • Depend strongly on the temperature • Decrease with decrease in temperature COMPRESSIVE STRENGTH ELASTIC MODULUS PROPOTIONAL LIMIT
  39. 39. FLOW • Change of shape or dimension in response to applied force • Caused by slippage of long chained wax molecules over each other • A measure of flow in the liquid state would be synonymous with viscosity of the molecules during movement. • Below the melting point the measure of flow would be a measure of the degree of plastic deformation of the material.
  40. 40. RESIDUAL STRESS • Stress remaining in wax as a result of manipulation during heating, cooling, bending , carving etc. • The release of stress at higher temperature causes an irreversible deformation that can destroy the fit of wax pattern • Regardless of the method used to prepare the wax pattern, residual stress exists in the completed pattern.
  41. 41. • To prevent residual stress – Wax not be carved or burnished at temperature well below their melting range – Carve with warm instrument – Melted wax added in small increments – Time between finishing and investing should be minimized
  42. 42. DUCTILITY • It increases as the temperature of the wax is increased. • Waxes with a lower melting temperatures have a greater ductility at any given temperature than those with a higher melting temperature. • A blended wax with components having a wide range of melting ranges generally has greater ductility
  43. 43. Classification • Pattern wax – Inlay wax – Casting wax – Base plate wax • Processing wax – Boxing wax – Utility wax – Sticky wax • Impression wax – Corrective wax – Bite plate wax
  44. 44. Pattern waxes • Used to form the general predetermined size and contour of artificial dental restoration , which is to be constructed of a more durable material. • 2 major properties: – Thermal change in dimension – Tendency to warp or distort on standing
  45. 45. Processing waxes • Used primarily as auxillary aids in the construction a variety of restorations and appliances either clinically or in the laboratory
  46. 46. Impression wax • Oldest recorded wax • Use of wax is limited to non-undercut edentulous portion of the mouth – Bite registration waxes – Corrective waxes
  47. 47. Inlay pattern waxes Classification:  type I (medium) direct technique  type II (soft) indirect technique Available as: blue, green, purple sticks. 7.5 cm long, 6 mm dia. Commercial names: harvard, kerr, peck etc.
  48. 48. Composition • INLAY WAX = Paraffin + Carnuba + Ceresin + Beeswax + gum dammar +synthetic wax+ Colorants
  49. 49. Desirable properties:  when softened, uniform..  Colour should contrast..  No flakiness/ rough surface..  Complete burn out..  Rigid, dimensionally stable..
  50. 50. Flow: lacks rigidity flows at room temp. do not solidify with space lattice type I – 1% at 37°C type I & II- 70-90% at 45°C
  51. 51. • Coefficient of thermal expansion : • The rate of expansion of type 1 inlay wax is greatest from just below mouth temp. to just above 450C • Knowing amount of expansion or contraction allows to judge compensation necessary to produce accurate casting
  52. 52. Distortion of wax pattern most serious problem to be faced Results from - • thermal changes and release of stresses arising from contraction, occluded air, and carving • Inlay waxes tend to return to their original shape after manipulation ‘ELASTIC MEMORY’
  53. 53. • This can be depicted by opening of a horse – shoe shape molded inlay wax kept in water after manipulation. • So to counteract the property of distortion, the pattern should be invested immediately on removal so as for best fitting of the casting. Ref :Phillip’s science of dental materials -Anusavice
  54. 54. CASTING WAX: type of pattern wax used to fabrication - CPD available as: sheets(28-38 guage) round half round half pear mesh work, shaped composition : paraffin, ceresin, Beeswax, resins
  55. 55. classification :  class A (28 gauge)  class B (30 gauge)  class C (readymade shapes)
  56. 56. • Ductility : – Has to be high • They must vaporize at about 500oC with no residue other than carbon • Pliable and readily adaptable at 40 o to 45 o C • Shall not be brittle on cooling
  57. 57. Base plate wax • It derives its name from its use on the baseplate tray in the technique for denture construction • Used to establish the vertical dimension, the plane of occlusion, and the initial arch form. • Pink color provides some esthetic quality in the initial stage of denture construction.
  58. 58. Composition – 80% ceresin – 12% beeswax – 2.5% carnuaba – 3% natural or synthetic resins – 2.5% microcrystalline or synthetic wax
  59. 59. • Practical requirements – No irritation of oral tissue – Softened sheets shall cohere readily without becoming flaky or adhering to fingers – Smooth surface after gentle flaming – Trim easily with a sharp instrument at 23 o C – No residue on porcelain or plastic teeth
  60. 60. Boxing wax • Use to form a plaster or stone cast from an impression of the edentulous arch. • Consists of adapting a long narrow stick or strip of wax around impression below its peripheral height followed by a wide strip of wax producing a form around entire impression . • Forms peripheral height.
  61. 61. • Should have slight tackiness which allows them to be attached to each other or to stone models or impression trays • In orthodontics these are called as periphery waxes • Can be easily melted to seal them to the impression surface • Composition : – Bees wax. Paraffin , soft waxes
  62. 62. Carding Wax • Dental literature occasionally refers to carding wax for use in boxing operation. • But it is the material on which porcelain or acrylic teeth were fixed when received from the manufacturer.
  63. 63. Utility wax • Easily workable ,adhesive wax • Composition – Bees wax, petrolatum. Other soft waxes • Used on the – Lingual portion of bridge pontic to stabilize it while a labial plaster splint is poured • Available as stick or sheet form-dark red or orange • Ductility & flow highest • Sufficient adhesive at 21-240C
  64. 64. Sticky wax • It is sticky when melt and adheres closely to the surface on which it is applied. • It is firm, free from tackiness and brittle at room temp.. • Should fracture rather than flow if it is deformed during soldering or repair procedures • Composition – Rosin , yellow bees wax, low and high melting resins , coloring matter, gum dammar
  65. 65. Corrective impression wax • Used as a wax veneer over an original impression to register the detail of the soft tissue . • Formulated from hydrocarbon waxes such as paraffin,ceresin & beeswax • The flow at 370C is 100 % • Records mucosa in functional state
  66. 66. Bite registration wax • Used to accurately articulate certain models of opposing quadrant • Formulated from beeswax or hydrocarbon waxes such as paraffin or ceresin and contain alumina or copper particle • 28 gauge wax sheets • Flow :2.5-22% at 37Deg - susceptible for distortion on removal from mouth
  67. 67. Conclusion • Many procedures in dentistry require the use of waxes . • A variety of waxes and resins have been used in dentistry for specific and well defined applications. • Restorative dentistry cannot be completed without use of wax as they are used for some of the highest precision work in dentistry.
  68. 68. References • Craig RG, Powers JM. Restorative dental materials .11th edition • Anusavice KJ. Phillips’ Science of DENTAL MATERIALS .11th edition • Combe EC. Notes On Dental Materials .5th edition • Anderson JN . Applied Dental Materials .5th edition
  69. 69. Thank You

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