DENTAL WAXES • Waxes are thermoplastic materials which are solids at room temperature but melt without decomposition to form mobile liquids WAXES Definition(GPT-8) One of the several esters of fatty acids with higher alcohols. Dental Waxes are combinations of various types of waxes compounded to provide desired physical properties. DENTAL WAXES • A low molecular weight ester of fatty acids derived from natural or synthetic components. Obrein, 268 CLASSIFICATION (based on application) DENTAL WAXES PATTERN WAX PROCESSING WAX IMPRESSION WAX • STICKY • CARDING • UTILITY BLOCK OUT IMPRESSION CASTING INLAY RESIN BASEPLATE PROCESSING PATTERN • • • • • BOXING • UTILITY • CORRECTIVE • OCCLUSAL REGISTRATIO N Mc Cabe • • • • Bite registration Disclosing wax Utility wax Low melting type 1 inlay wax Lab waxes Clinical use CLASSIFICATION • Boxing wax • Sticky wax • Beading wax Based on source • • • • Mineral wax Paraffin Montan Barnsdhal. Ozokerite Microcryst alline Plant wax Insect wax • Carnauba • Ouricury • Candellila • Japan wax • Cocoa butter • Bees wax Animal wax • Spermaceti wax COMPOSITION OF DENTAL WAXES • • • • • • • • Paraffin wax- 60% Bees wax-5% Carnauba wax-20% Candelilla wax Microcrystalline wax Synthetic wax-2% Gum damar-3% Ceresin -5% Paraffin wax • • • • Most dental waxes contain 40-60% paraffin A mineral wax obtained from refined crude oil (high boiling fraction of petroleum) White, transparent • Presence of oils lowers the melting point. • Paraffin wax used in dentistry have <0.5 % oil. • They crystallize in the form of plates, needles and crystals, but are usually of the plate type. BEES WAX • Derived from secretions that bees use to build honey combs.(insect wax) • Is a complex mixture of esters, consisting mainly of myricyl palmitate plus saturated and unsaturated hydrocarbons and organic acids. • • Brittle . • Intermediate melting range-60-70 degree • Added to dental wax because of its desirable flow properties at oral temperature. CARNAUBA WAX • fine powder on the leaves of certain tropical palms. • It is known as "queen of waxes one of the purest wax. • usually comes in the form of hard yellow-brown flakes. • Hard ,tough with high melting range • Added to toughen Paraffin and raise melting range • So flow decreases . • Imparts glossy surface. Addition of 10 % carnauba wax to paraffin wax with a melting range of 200C will increase the melting range to 460C. CANDELILA WAX o leaves of the small Candelilla shrub native to northern Mexico and the southwestern US. o Melting range 68-75°C. o Increases the hardness. o similar qualities as carnauba wax Euphorbia antisyphilitica CERESIN • Ceresin is a term that describes waxes from distillates of natural mineral, petroleum, or lignite refining. • They contain straight and branched hydrocarbon chains of higher molecular weights. • • Harder than other hydrocarbon waxes. CERESIN • Typically a white wax extracted from ozokerite- waxy mineral mixture of hydrocarbons • Replaces part of paraffin to modify toughness and carving characteristics of wax. MICROCRYSTALLINE WAX • Litene and barnsdahl are micro crystalline waxes similar to paraffin but obtained from heavier oil fractions. • composed of branched hydrocarbons • crystallize in small plates. • tougher and more flexible than paraffin. Ouricury Wax • Ouricury wax is a brown-colored wax obtained from the leaves of a Brazilian Feather Palm by scraping the leaf surface. • Gloss and hardness. Synthetic Waxes • Complex organic compounds produced by reaction with natural waxes. • More refined than natural waxes . • Specific melting points. • Use in dental formulations is limited as they have limited compatibility with other waxes. Types • Polyethylene waxes • Polyoxyethylene glycol waxes • Halogenated hydrocarbon waxes • Hydrogenated waxes POLYETHYLENE WAX • Polyoxyethylene waxes are polymers of ethylene glycols. • melting temperature - 37 °C - 63°C function as plasticizers and toughen films of wax Montan Wax • It is a hard wax obtained through solvent extraction of certain different types of lignite or brown coals. • As a result, montan wax is hard and brittle. • Melting range 72-92°C • Improve hardness and melting range of paraffin waxes. • Blends well with other waxes Spermaceti Wax • Obtained from sperm of whales. • Mainly esters • Used as a coating in the manufacturing of dental floss Gum Dammar • Obtained from a certain family of trees in India and East Asia • Damar is produced by tapping trees • some is collected in fossilized form from the ground. • Clear to pale yellow • fossilized form is grey brown • Composition - less than 1% • Added to paraffin to improve its smoothness in molding. • Increases the toughness of the wax- renders it more resistant to cracking and flaking. • enhances the lustre of the wax. DESCRIPTION OF WAXES IN DENTISTRY PATTERN WAXES INLAY WAX CASTING WAX PATTERN RESIN BASEPLATE WAX 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 • INLAY WAXES • used to make patterns for Inlays, crowns & bridge units by lost wax casting technique . • pattern of wax duplicates shape and contour of casting . • After investing & spruing the wax is eliminated by heating Composition of inlay wax • • • • • • • Paraffin- 60% Carnauba- 2o% Ceresin- 10% Bees wax- 5% Gum dammar-5% Microcrystalline wax-minute Coloring agents Type I - Direct • •Revised ANSI/ ADA Sp. No. – 4 • Hard wax used for forming patterns directly in mouth. • It must soften at a temp that is not hazardous to pulp and must harden above mouth temp. • Rarely used method because of its sensitivity to changes in pressure, temperature and heating and cooling rates during manipulation. • • A wax pattern made in the mouth will shrink appreciably as it is cooled to room temperature Type II - Indirect • Softer wax used for indirect technique. • Dark blue-hard, for crowns bridges and inlays. Add on and Dip use –MP- 690C • Light blue-soft, for crowns bridges and inlays,add on and dip use –MP-720C • Lilac-stress free, for copings and cervical margins • MP- 790C • Red- adhesive, connecting and adhesive wax, MP 700C PATTERN RESIN • Are characterised by higher strength and resistance to flow than waxes. • Good dimensional stability. • Burn without residue. • Full crown patterns made with resin and inlay waxes have similar marginal discrepancies. PATTERN RESIN • A pattern is fabricated by applying resin in 3-5 mm layers and curing in a light chamber or with hand held light curing unit. • Resin is completely eliminated from mold before casting by heating. DENTAL CASTING WAX • Used for thin sections of certain removable and fixed partial denture patterns • Convenient in preparation of copings or clasps requiring uniformly thin regions • ADA no 140 Types of casting wax. CLASS 2 CLASS 3 • Blue sheets • Burn outͦ • No carbon residue CLASS 1 BASEPLATE WAX • ADA no 24 • made from 75% paraffin or ceresin • Used for constructing full denture patterns and occlusal rims. • Also for bite registration • Hard and brittle at room temp TYPES OF BASEPLATE WAX • Type 1- soft • For veneers and contours • Type 2-medium hardness designed for temperate climate • Type 3-hardest • for pattern try in at tropical climates • Hardness is based on amount of flow the wax shows at 45 ͦ C PROCESSING WAX • • • • • • Boxing wax sticky wax carding wax block out wax white wax utility wax BOXING WAX • Mouldable at room temp • Can be easily pressed to desired contours around the perimeter of an impression and • To form containers for pouring casts. Undercut/block out wax • To fill voids and undercuts for RPD fabrication Wax rim /bite rim • Softening temp -above mouth temperature • Tough and resist fracture during removal from cast • uses: arrange teeth • Restoring occlusal relation Sticky Wax • A mixture of waxes, resins & other additives • Sticky when melted, adheres closely to dry clean surfaces • Temporarily join gypsum components. • Stabilize components of bridge befor soldering. • Attach pieces of broken dentur prior to repair. IMPRESSION WAXES Iowa Wax-White • H-L physiologic paste-yellow white • Adaptol -.Green • Korecta Wax No 4. - Orange • KORRECTA WAX • Soft NO. 4 - (Orange) Soft NO. 3 - (Red) • Hard NO. 2 - (Yellow) Extra Hard No. 1 - (Pink) • CORRECTIVE IMPRESSION WAX • Paraffin wax:bees wax-3:1 • For flow at mouth temp • Use; to correct small imperfections and air blows in ZnOE impression. • Disadvantages: easily distorted • So pour cast immediately BITE REGISTRATION WAX • interocclusal records • High resistance to closure • High coeff of thermal expansion. Bite Wafer-U-shaped- • Used for checking occlusal relationships. • Thin foil layer prevents teeth from biting through. ALUWAX • Alu Wax- used to verify jaw relation records. • Contains Aluminum and Cuprex chloride OCCLUSAL INDICATOR WAX To detect areas of premature occlusal contact Diagnostic wax • diagnostic wax - formulated for planning and creating esthetic life like presentations.( diagnostic wax up) • It can be easily carved, excellent stability, low shrinkage and burns out clean. • PONTIC WAX Pontic wax is a general crown and bridge wax and can be used for margins. It has zero shrinkage. METHODS OF SOFTENING WAX • Bunsen burner-hold wax in warm air above flame. • Water bath-more regular softening. ▫ Dis adv-water incorporation. ▫ Components may leach out. ▫ Infrared lamp-250 W –standardisation test of waxes Wax annealer-ideal method ▫ Thermostatically controlled oven. Properties • • • • • • • Melting range • Thermal expansion • Mechanical properties • Flow • Residual stress • Ductility Melting Range • Have a range as they contain several types of molecules, each having a range of molecular weight • Melting temperature: • Beeswax is 62.8°C. • Paraffin wax is 52°C. • Melting range: Beeswax is 34-70° C. • Paraffin wax is 44- 60°C Thermal Expansion • Waxes have the largest co- efficient of thermal expansion among all dental materials. Flow • It indicates the degree of plastic deformation at a given temp. • Flow is greatly increased as melting point is approached . • Result of slippage of molecules over each other. Application • A direct inlay wax should have a high flow just a few degrees above the mouth temperature so it is not too hot in workable condition. • Should have a no flow at mouth temperature so that it does not distort during removal of pattern. • The flow of corrective wax at 37°C is 100% • bite registration wax is 2.5%-22% Mechanical Properties • • • • • Elastic modulus • Proportional limit • Compressive strength All are low when compared to other materials Elastic Modulus • • • • carnauba wax is highest • Bees wax – lowest • Decreases with increase in temperature. • Inlay wax (simulates a mixture of 75% paraffin & 25% carnauba wax) – 760 to 48.2 MPa ( 23°C& 40°C Residual Stress • Residual stresses always exist in a prepared wax pattern . To minimize distortion • .Use higher temperature at time of formation – less force to shape – less residual stresses Soften the wax uniformly at 50°C for 15 min Warmed carving instruments & die. DIMENSIONAL CHANGE AND WAX PATTERN DISTORTION DURING AND AFTER MOLDING • Wax molded into a cavity will show two types of shrinkage: • one is the shrinkage during solidification, • and the other is the cooling shrinkage after solidification. • contraction during solidification is much larger than the thermal shrinkage that occurs after solidification. Rheology of dental waxes. • “pressmolding”-technique in which softened wax was molded in the mold by a heavy finger pressure. • “pour and press-molding” technique in which fluid wax was poured in the mold and held by a heavy finger pressure before hardenin. • “pour-molding” technique in which fluid wax was poured in the mold and no pressure was applied. • the press-molding technique produced the most accurate patterns • the other two techniques using fluid wax resulted in greater shrinkage. Penetration of Commercialand DentalWaxes J. M. POWERS, R. G. CRAIG,JDR,1974 • Annealing paraffin increases the crystallinity of the lattice • increased crystallinity offers more resistance to penetration • Annealing paraffin at 40 C for 24 hours was shown to increase the resistance to penetration. CONCLUSION • These different dental waxes work quite well and are inexpensive and surprisingly not replaced by newer high tech materials.. REFERENCES • Dental Materials And their Selection William J .O Brien 3 rd ED • Kenneth j. Anusavice ; Phillips Science of dental material .Eleventh edition, Elsevier,2004. • Robert C. Craig John M. Powers, John C.Wataha ;Dental materials properties and manipulation,. Eight edition,2004. • Kenneth j. Anusavice ; Phillips Science of dental material .Eleventh edition, Elsevier,2004. • Robert C. Craig John M. Powers, John C.Wataha ;Dental materials properties and manipulation,. Eight edition,2004. • Craig’sRestorative Dental Materials. John M. Powers.Ronald .Sakaguchi • Dental Materials And their Selection William J .O Brien 3 rd ED Yellow bite wax Carnauba did not flow until it reached a very high temperature close to its setting range, and the sharpCarnauba sloping curve did not flow until it reached a illustrates that this wax flowed over a smallclose to its setting very high temperature temperature range. range, and the sharp sloping curve illustrates that this wax floweCarnauba did not flow until it reached a very high temperature close to its setting range, and the sharp sloping curve illustrates that this wax flowed over a small temperature range. d over a small temperature range. Red Indicator Wax • The user scans a model • A virtual wax-up is designed using 3-D software • Data is sent to the ProJet™ Production System to "print" wax-ups in layers • Accepts standard STL file • The system can generate hundreds of units each cycle. The wax-ups have a smooth surface finish and can be cast or pressed with conventional techniques. • DTA measurements2 indicate that the beeswax used in this study is a mixture of hydrocarbon and ester waxes, each of which has a distinct endothermic melting transition. At the lower stress, the higher melting component provides sufficient integrity to the wax for it to resist penetration, although the lower melting component has undergone a major phase transition. The resistance of beeswax to penetration is influenced at high stress levels by the temperature at which the lower melting component transforms. Carnauba wax is a relatively pure, highmelting ester wax.2 Penetration at both stress levels corresponds to the melting transformation: penetration at the higher stress level occurs at the onset of the melting transition and penetration at the lower stress level occurs near the completion of the melting transition. At the two levels of stress studied, the solidsolid transition of carnauba, which occurred at 61.0 C, had no influence on penetration • mineral waxes generally expanded SETTING RANGE Time Interval, Minutes 0 0 I- 401 , , , a I I I 0 10 20 30 40 50 60 70 80 Length of Run, Minutes FIG. 2.-Setting-range test of Kerr hard wax and Japan wax. J. dent. Res. November-December 1965 the greatest amount. Paraffin had the highest coefficient of thermal expansion of any wax tested, which was 1,631 ± 237 X 10-6/0 C. between 27.80 and 34.0 C. Litene, a mineral wax, had higher coefficients of thermal expansion between 220 and 520 C. than did ouricury, a plant wax, even though both waxes solidified over the same temperature range. • Yellow beeswax, which is also primarily an ester wax, flowed extensively 240 C. below its setting range and displayed an 80 C. temperature difference between 1 and 70 per cent flow. This may be explained by the fact that yellow beeswax contains a large number of impurities which interfere with the secondary valence forces. As beeswax goes through the bleaching process and some of these impurities are removed, the secondary valence forces increase. The flow data illustrate this point, since bleached beeswax required a temperature closer to its setting range to produce a large amount of flow, and the temperature difference between 1 and 70 per cent flow was only 40 C • MIontan wax was the only mineral wax which required a temperature as high as 710 C., or 80 C. below its setting point, in order to flow 50 per cent. This wax, however, is similar to the plant waxes in that it is composed mainly of esters formed in nature by the union of higher alcohols with the higher fatty acids. The plant waxes also required temperatures close to their setting ranges to produce 50 per cent flow. Due to the presence of esters groups in these waxes, the secondary valence forces are rather strong, and a high temperature is necessary to overcome these forces. Once the secondary valence forces are overcome, these waxes flow rapidly; below this point, however, they often appear to fracture in a manner similar to a brittle material. • Bennett'5 as the transformation from needleshaped crystals to rhomboid plates or leafy masses. These findings also are in agreement with those of Lasater,5 who has reported arrest points in dental waxes which he related to the distortion of wax patterns. This second-order transition point presents difficulties in that internal stresses result in wax patterns and it would be better if this point were well below room temperature. The use of microcrystalline waxes which have minute crystals and less orientation is preferred, and these should produce a more stable wax. • jor waxes. The setting-range measurements illustrate that waxes are partially amorphous and partially crystalline, with the rate of FLOW vs. TIME KERR HARD WAX (blue) Bennett'5 as the transformation from needleshaped crystals to rhomboid plates or leafy masses. These findings also are in agreement with those of Lasater,5 who has reported arrest points in dental waxes which he related to the distortion of wax patterns. This second-order transition point presents difficulties in that internal stresses result in wax patterns and it would be better if this point were well below room temperature. The use of microcrystalline waxes which have minute crystals and less orientation is preferred, and these should produce a more stable wax. The importance of flow of wax at different temperatures has been emphasized by Taylor et al.1 2 and Stanford et al.3 Yellow beeswax did not flow extensively until it THERMAL EXRPNSION 40.0 eC 5 6 7 8 9 10 Time, Minutes FIG. 4. Flow curves at various times for Kerr hard wax. temperature change during solidification indicating the degree of crystallinity • Kerr's hard inlay wax expanded less than Kerr's regular inlay wax. It is interesting to note that Kerr's hard inlay wax showed an increase in the rate of expansion at 37.50 C., or mouth temperature, and a decreased rate of expansion at 45.0° C. Kerr's regular inlay wax, however, had an increase in the rate of thermal expansion at 32.70 C., a decrease in rate of expansion at 40.9° C., and an increase again at 46.90 C. The linear coefficient of thermal expansion for the mineral, plant, and insect waxes increased as the temperature ranges approached the solidification ranges of the waxes.
