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1. dental waxes Dr Sanchi Soppimath, 1 st year MDS, Dept of prosthodontics

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

3. Introduction 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. History 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 fabricating porcelain inlay in 1855. First cast inlay is attributed to PHILBROOK in 1897. TAGGART in 1907 introduced lost wax technique

5. CLASSIFICATION 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 Bite registration Disclosing Type I inlay Boxing Base plate Sticky Beading Utility Hard, medium, and soft type II inlay-type waxes

6. Waxes Pattern Processing Impression Inlay Casting Base plate Boxing Utility Sticky Occlusal registration 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. Composition 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 Mineral Plant Insect Animal Poly ethelene Poly oxyethelene Oils Colors Fats Natural resins 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. PROPERTIES of dental waxes MELTING RANGE Waxes have a melting range rather than a melting point. Example : paraffin 44 – 62 C⁰ , carnauba 50 – 90 C⁰. Significance: Mixing of waxes can change their melting range. COEFFICIENT OF THERMAL EXPANSION Waxes expand when there is increase in temperature and contract when there is decrease in temperature. 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. DESIRABLE PROPERTIES OF WAX The wax should be uniform when softened . The color should contrast with die materials or prepared teeth. The wax should not fragment into flakes or similar surface particles when it is molded after softening. The wax must not be pulled away by the carving instrument or chip as it is carved or such precision cannot be achieved.

17. 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. 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. TYPES OF INLAY WAX 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 coefficient of thermal expansion 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. MANIPULATION OF INLAY WAX 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.

25. 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.

26. 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.

27. Fabrication of wax pattern A pattern of wax that, when invested and burned out or otherwise eliminated, will produce a mold in which a casting may be made. WAXING INSTRUMENTS PKT set: designed by Dr Peter K. Thomas. it consists of five instruments each with a specific use:

28. PKT No. 1 is used for positioning of functional and non functional cusps. The marginal, cusp and triangular ridges are also added with PKT No. 1. PKT No. 2 is used for eliminating voids remaining on the occlusal surface. Developmental and supplemental grooves are smoothened with PKT No. 3. Smoothening of axial surfaces is done with PKT No. 4. And PKT No. 5 is used to refine the ridges No 7: wax spatula is used for adding large amount of wax.

29. Electric waxing instruments: They also available for adding wax Advantage: Allows precise temperature control Carbon buildup in instruments due to overheating will be minimal.

30. POSTERIOR CROWN OR RETAINER 1.coping fabrication The coping can be made up of resin. It must reproduce the retentive features of the restoration. The die is first coated with a die spacer followed by a die lubricant to facilitate easy removal of pattern. The coping is formed by adding wax with a No 7 wax spatula or dipping the die into molten wax. Ensure the previous layer is hardened before the addition of new layer. This prevents the formation of voids and flow lines. The proximal areas should be bulk to help removal from die.

31. 2.Axial contours This involves fabrication of the proximal, buccal and lingual surfaces. Proximal occulsogingival : occlusal third of the other posterior crown. And maxillary first and second ,molar in the middle third. Faciolingual : facial aspect of the middle of the posterior teeth. And maxillary first and second molar centered faciolingually . Buccal and Lingual surface: should follow the contour of adjacent teeth. Height of contour of buccal and lingual surface of maxillary posterior occurs in the cervical third of the teeth but the mandibular posterior occurs in middle third. Emergence profile is the contour of a tooth in relation to the gingival tissues or below the height of contour. Should be straight or concave.

32. Occlusal surface Functional and non functional cusps are located. Wax cones are placed for these cusps with PKT No. 1. Cones for non functional cusps should be shorter than functional cusps to provide easy disocclusion during excursion. Then the marginal and axial ridges are added with PKT No. 1. Marginal ridges should never be at a higher level than cuspal cones. And proximal contacts with posterior natural teeth are located in the occlusal thirds of the pattern. Triangular ridges are added next. They are necessarily triangular in shape extending from central groove to the cuspal tip. Tip of the triangular ridge is at the cusp tip and base in the central groove. If triangular ridges are developed correctly proper groove pattern will occur as a natural by-product. Finally grooves are smoothened with PKT No. 3 and marginal ridges are smoothened with PKT No. 5 to form the refined final wax pattern with proper occlusal morphology

33. Remargination : to obtain optimum fit, the margins must be refabricated and finished just before investing the wax pattern. Procedure: The die is lubricated and pattern is reseated. The entire margin is remelted using a PKT No 1 ensuring that wax is melted through to die. This results in depression. The depression is filled with additional wax. The margin is finished by carving. A sharp instrument should not be used. FINISHING AND POLISHING Cotton pellet held by tweezers and dipped in die lubricant is used to finish the occlusal surface. The axial walls are smoothed and finished using wet silk cloth and liquid detergent. REMOVING WAX PATTERN the pattern is held by thumb and forefinger of one hand while force in the opposite direction is applied by holding the die with thumb and forefinger of other hand.

34. SPECIALITY WAXES Baseplate wax Supplied in 1- to 2-mm-thick red or pink sheets. COMPOSITION : Paraffin wax: 70-80% Bees wax: 12% Carnuaba wax: 2.5% Resins: 3% Synthetic waxes: 2.5%

35. They are sheets of wax generally pink or red in colour to simulate the colour of gingiva. Uses: 1) To form occlusal rims to establish - vertical dimension - plane of occlusion - initial arch form 2) To produce desired contour of the denture after teeth are set in position .

36. 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.

37. 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.

38. 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.

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

40. 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.

41. 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.

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

43. 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.

44. 6. Impression waxes : Corrective wax : Wax in combination with resins of low melting point can be used in corrective impression technique in partial and complete denture prosthesis. The peculiarity of impression wax is that they flow at mouth temperature. Availability : sheets or cakes Uses: As a wax over an original impression to contact and register the details of the soft tissue.

45. 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

46. 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.

47. 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.

48. Recent advances Conventionally, wax patterns were fabricated with wax and waxing instruments for example the popular PKT instruments. 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.

49. 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.

50. 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.

51. refernces 1. Anusavice K.J.-“Phillips’ Science of Dental materials” 11 th edition , 2003.Pg 283-292. 2. Craig’s R.G. Powers J.M. – “Restorative Dental Materials” 12 th edition,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.

52. 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.

53. Thank you