3.DENTAL WAXES.pptxxxxxxxxxxxxxxxxxxxxxxx

dental waxes ppt

1. DENTAL WAXES PRESENTED BY: ANUKRITY CHANDRA MDS 1 ST YEAR GUIDED BY: Dr. SUDHEER ARUNACHALAM Dr. TUSHAR TANWANI Dr. ANUPAM PURAWAR Dr. SUDEEPTI SONI

2. CONTENTS INTRODUCTION DESIRABLE PROPERTIES OF WAXES PHYSICAL PROPERTIES. COMPOSITION OF WAXES COMPONENTS OF WAXES CLASSIFICATION DENTAL WAXES. CONCLUSION REFERENCES

3. INTRODUCTION WAXES are thermoplastic materials which are normally solids at room temperature but melt without decomposition to form mobile liquids. They are essentially, soft substances with poor mechanical properties. Primarily used in dentistry to form patterns of appliances prior to casting Other uses: impression making , bite registration, and in processing of laboratory procedures.

4. DEFINITION A thermoplastic molding material that is solid at room temperature and when subjected to moderate temperatures become low viscosity liquid. Waxes are esters of fatty acid, alcohol, or hydrocarbons. They are insoluble in water but soluble in most organic solvents .

5. Dental wax 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 relatively low temperature. A mixture of two or more waxes and additives used as an aid for the production of gypsum casts, productions of non-metallic denture bases, registering jaw relation, and laboratory work -Phillip’s science of dental materials, 12 th edition

6. Sources of wax Carnauba wax – copernica cerifera Candelilla wax- E. cerifera , E. Antisyphilitica . Ouricury wax- syagrus coronata . Castor wax- C astor oil. Bees wax- honey bees. Shellac wax- kerria lacca Chinese wax- ceroplastis ceriferus .

7. Animal wax : Lanolin , spermaceti Petroleum waxes : Paraffin wax , microcrystalline wax Mineral wax : Ozokerite , ceresin, montan wax Synthetic waxes : polyethylene , Polyoxyethylene glycol

8. DESIRABLE PROPERTIES OF WAXES When softened , the wax should be uniform. The colour should be contrast with die material. No flakiness or surface roughening. Wax should burnout completely – leave no residue. Completely rigid and dimensionally stable. Allow careful handling – show less distortion.

9. PROPERTIES OF WAXES MELTING RANGE FLOW COEFFICIENT OF THERMAL EXPANSION RESIDUAL STRESS DUCTILITY

10. MELTING RANGE Waxes do not melt at a single temperature . So they do not have a melting point ,they have a melting range. The lower limit of melting range controls the applicability. Paraffin wax – 50˚C - 70˚C Bees wax - 60˚C - 70˚C Carnauba wax- 65˚C - 90˚C Microcrystalline waxes- 65˚C - 90˚C

11. SOLID- SOLID TRANSITION TEMPERATURE 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.

12. Coefficient of thermal expansion THERMAL EXPANSION is the tendency of matter to change in volume in response to a change in temperature, through heat transfer. Linear coefficient of expansion –change in length per unit of the original length of a material when its temperature is raised by 1˚C For most solid materials, the volumetric coefficient of thermal expansion can be considered to be thrice of that linear CTE

13. Waxes have very high CTE, particularly around the melting range, and very high residual stress ; they have the highest CTE as compared to all other materials used in dentistry. CTE of typical pattern wax is 323x10/ C but that the dental porcelain is 20 times less 14x10/C Small changes in temperature can cause a sufficient change in dimension to make the pattern inaccurate

14. Thermal conductivity The thermal conductivity of the waxes is low, and sufficient time must be allowed both to heat them uniformly throughout and to cool them to body or room temperature

15. Mechanical properties Modulus of elasticity, proportional limit and compressive strength are less for waxes All these factors depend on temperature.

16. Flow Flow of waxes is desirable as a part of moulding process but becomes undesirable after the wax pattern or impression has been made Mineral waxes – paraffin, ceresin- 50% flow at mouth temperature Yellow bees wax – No flow at 32˚c 70% flow at 40c

17. Residual stress It is the stress remaining in a wax as a result of manipulation during heating, cooling, bending, carving or other manipulation The release of residual stress at higher temperature causes an irreversible deformation that can destroy the fit of a wax pattern The warpage is due to the residual stresses which result from the heating of a wax specimens formed under compression or tension

18. It will result in a dimensional inaccuracy and is undesirable . The longer the wax pattern is left before being invested , the greater the distortion that must be result Crystalline waxes develop more internal stresses when manipulated below the transition temperature Extent of change in thermal expansion depends upon Magnitude of residual stresses Time and Temperature of storage specimen

19. Minimizing the warpage Use higher temperature at the time of formation – less force to shape less residual stresses Soften the wax uniformly at 50 degree Celsius for 15 min. Warmed carving instrument and die. Adding wax to die in small increments

20. Ductility The ductility of a material represents its ability to be drawn into wire under a force of tension It is a property related to the workability of a material in the mouth Highly refined waxes are quite brittle. Wide melting ranges – greater ductility. eg : Microcrystalline mineral waxes .

21. Composition The dental waxes are 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 Colouring agents are added for contrast of wax patterns against tooth, die, and model surfaces

22. Most dental waxes contain 40%- 60% paraffin by weight , which is derived from high boiling fraction of petroleum They are composed mainly of a complex mixture of hydrocarbons together with minor amounts of amorphous and microcrystalline phases The melting temperature generally increases with increasing molecular weight Paraffin wax is likely to flake when it is trimmed , and it does not produce a smooth, glossy surface which is desirable for an inlay wax

23. Gum dammar – or dammar resin is a natural resin. It is added to the paraffin to improve the smoothness in moulding and to render it more resistant to cracking and flaking. I t also increases the toughness of the wax and enhances the smoothness and lustre of the surface. Carnauba wax occurs as a fine powder on the leaves of certain topical palms. This wax is very hard , and it has a relatively high melting point and has an agreeable odour It is combined with paraffin to decrease flow at mouth temperature.

24. 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. Ceresin is typically a white wax extracted from ozokerite , a waxy mineral mixture of hydrocarbons that is colourless or white when pure but it has a somewhat unpleasant odour. This may be used to increase the melting range of paraffin waxes. Montan waxes are hard brittle and lustrous ; they blend with other waxes and therefore often substitute to increase the melting range of paraffin waxes.

25. Classification OF WAX

26. Pattern waxes Inlay wax : ADA specification no 4 Supplied in the form of small pellets and cones Uses: It is used to make pattern for metallic restoration Pattern for inlay Crown and bridges are first made in wax and then converted into metal or ceramic by casting

27. Ideal requirement of inlay waxes When softened the wax should be uniform. There should be no granules on the surface and hard spots within the surface when the wax is softened. The colour should be contrast with the die or prepared teeth. A defined colour contrast helps in identifying and finishing. The wax should not chip, flake or tear during carving. The wax should be able to disintegrate and volatilize so that it could be eliminated completely without residue during burn out or wax elimination procedure. The wax pattern should be completely rigid and dimensionally stable at all times until it is eliminated

28. Composition Inlay wax is composed of paraffin wax, gum dammar, carnauba or candelilla and colouring agent. Paraffin wax is the main component (40% - 60%) which is used to establish the melting range Being the main component ,gum dammar, carnauba , candeililla wax are added to modify its properties Colouring agents are added for contrast of wax patterns against the tooth, die or model surface.

29. Classification TYPE I : Medium wax employed in direct technique TYPE II : Soft wax used for indirect technique , for inlays and crowns. 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 mouth will shrink appreciably as it cooled to room temperature

30. Indirect technique : T he 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. A regular or soft type of a wax is typically used for indirect work at room temperature or in a cool weather. A harder or medium type with a flow property is indicated for use in warmer climates. A pattern made by the indirect method may not shrink as much.

31. The first procedure in casting of an inlay or crown for the lost wax process is the preparation of dental wax pattern by direct or indirect technique. The wax pattern forms the outline of the mould 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.

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

33. Manipulation of I nlay wax Waxes oxidizes 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 water bath The later 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 To avoid distortion during removal of the pattern, it should be penetrated slightly with an explorer point and carefully removed from the cavity

34. After removal touching the pattern with 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 spatula or a waxing instrument. 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 towards the margin.

35. Some clinician 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

36. Wax Distortion Distortion of a wax pattern results from occluded air in the pattern, physical deformation ( during moulding, 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 condition are established. Waxes tend to return partially to their original shape after manipulation. This is known as elastic memory.

37. Casting wax It is a type of pattern wax Classification according to FDI specification no. 140 USES : To make patterns of the metallic framework and sprues of removable partial denture SUPPLIED AS: ● sheets of thickness 0.3-0.4mm ● Preformed shapes ● Bulk form ●Rolls or coils of various diameters ranging from 2-5 mm for forming sprue

38. CLASSIFICATION: Class I : (28 gauze) Class II: ( 30 gauze) Class III: ( readymade shapes) COMPOSITION: Paraffin, ceresin , beeswax and resins PROPERTIES: These waxes are highly ductile Pliable and readily available at 40- 50˚C Do not become brittle on cooling

39. Baseplate waxes ADA specification no 24 USES: To establish the initial arch form in construction of complete denture and used to produce desired contour of the denture after teeth set in position It establish the pattern for final denture. SUPPLIED AS Sheets of pink or red color having 1-2 mm thickness COMPOSITION Paraffin wax -75% Beeswax and other resins and waxes Both to set denture teeth and to adapt around these teeth and to develop proper contour

40. Wax rim ( bite rim) It is a type of pattern wax It is tough and resist fracture during removal from the cast. USES: Restoring the occlusal relationship Arrangement of teeth Checking the denture inside the patient mouth.

41. Processing waxes Boxing wax and beading wax It is a type of processing wax. USES Beading was 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

42. Advantages of beading and boxing Preserve the extension and landmarks. Controls the thickness of the borders. Controls the form and thickness of the base of cast. Conserve the artificial stone. Properties: They are pliable and can be adapted easily. A slight tackiness allows it to stick to the impression

43. Utility wax Composition: Consist mainly of beeswax and petrolatum and soft waxes in varying proportion. Supplied as: It is available in the form of sticks and sheets . Orange or dark red in colour. Flow at 37.5˚C – minimum 65% and maximum 80% Pliable and tacky at 21-24˚C USES: It can be used to alter the stock tray extension. It is pliable and can easily be molded It is adhesive and can stick to the tray

44. Sticky wax It is a type of processing wax. It is sticky when melted with a max 5% flow at 30˚c and 90% flow at 43˚c and adheres closely to the surfaces when applied to it If movement occurs the wax tends to fracture then distort USES: It is used to align fracture parts of acrylic dentures. It is used to align fixed partial denture units before soldering.

45. Sticky wax is used to join and stabilize temporarily the components of a bridge before soldering and also to stabilize pieces of a broken denture before the repair It is quite tacky when melted , but firm and brittle when cooled. Sticky wax adheres closely to the surfaces on which it is applied. Should fracture rather than flow if it i s deformed during deformed during soldering and repair procedure

46. Carding wax It is used by manufacturers for the packaging of acrylic or porcelain teeth. They are soft tacky and pliable at room temperature. They are available as sheets

47. Impression waxes Corrective wax: Wax in combination with resins of low melting range 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. It records mucous membrane and underlying tissue in functional state in which movable tissue is displaced in such a degree that functional contact with the base of denture is obtained. Available as : sheets or cakes Its main disadvantage is that it is distorted. It flows 100% at 37˚C

48. Bite registration wax It is used to record relationship of the upper and lower teeth in dentulous patient. Wax is softened under hot running water. Full arch quadrant or just a few teeth can be taken. 28 gauze casting wax or hard base plate wax , bees wax , hydrocarbons are used in bite registration wax. It flows 2.5%- 22% at 37 C Susceptible to distortion from removal from mouth. Occlusal registration made from addition silicon, elastomers become more popular because of their high elastic recovery and dimensional stability.

49. Conclusion Waxes are use in r estorative dentistry like forming an inlay patterns, registration of occlusal bite relationship, boxing an impression and other processing steps, each requires a specially formulated wax. And have different features of every wax. So proper knowledge in needed of their characteristics. For proper handling and manipulation.

50. References Anusavice K.J – “Phillips Science of Dental materials” 11 th edition, 2003. Pg 283- 292 Craig’s R.G. Powers J.M – “Restorative Dental Materials” 12 th edition, 2006. Pg 338- 355

51. Thank you