Dental Waxes PDF

DENTAL WAXES Lecturer: Dr. Sagon- Kendall Introduction Wax compounds use d in de nti stry are mix ture s o f individual wax e s of natur al or synthe tic origin. A s with all othe r de ntal mater ials, e ach compone nt in the mix ture i s se le cte d to give the spe cifi c pr ope rtie s be st su...

DENTAL WAXES Lecturer: Dr. Sagon- Kendall Introduction Wax compounds use d in de nti stry are mix ture s o f individual wax e s of natur al or synthe tic origin. A s with all othe r de ntal mater ials, e ach compone nt in the mix ture i s se le cte d to give the spe cifi c pr ope rtie s be st suite d for the proce dure be ing pe rform e d. De pe nding on the purpose the wax se r ve s, modifi er s ar e include d to change the me lting range, incre ase or de cre ase stickiness, or impart a distinguishi ng color. De ntal wax e s ar e supplie d in varie s size s, colour s, compositions and shape s. Properties of Dental Waxes Dental waxes are chemical polyesters of fatty acids and alcohol forming hydrocarbon chains, that is, chains of carbon atoms linked to each other and to hydrogen atoms or other radicals. There is a wide variety of waxes for dental use and in general terms, we could say that most of them are made up of a mixture of waxes of animal, vegetable and mineral origin, as well as other products such as oils, fats, gums, resins, synthetic waxes and dyes.  Properties of Dental Waxes The diff erent types of dental waxes share the same physical properties: 1. Melting range: Dental waxes are made up of diff erent molecules and although they are similar to each other, they have diff erent molecular weights. This property means that, instead of having a specifi c melting point, they have melting intervals. 2. Thermal expansion: Dental waxes expand with increasing temperature and contract with decreasing temperature. 3. Flow: Important especially in inlay waxes. When melted, the wax should fl ow readily into all the parts of the die. Flow is dependent on: a. Temperature of the wax b. Force applied c. The length of time the force is applied Properties of Dental Waxes 4. Residual stress: Cooling the wax under compression forces the atoms and molecules closer together and reheating the wax releases the stress, causing a dimensional change. 5. Ductility: If you increase its temperature you can stretch the wax like a wire. -Distortion of the wax pattern: Distortion increases with time and also depends on the storage temperature. This occurs because the residual stress developed during the fabrication of the wax pattern is released. Properties of Dental Waxes 6. Mechanical properties: The elastic modulus, proportional limit and compressive strength of waxes are low compared to other dental materials. These properties are strongly dependent on the temperature.  Types of Dental Waxes Material Uses Remarks Baseplate Wax Denture wax-up, fill tongue Suplied in medium or hard space of a lower impression types. Most baseplate wax sheets are about 1 mm thick Inlay Wax Wax patterns:inlays, onlays, Highest requirements for crowns and pontic, RPD frame accuracy of any wax. wax ups Supplied in medium and hard types Ivory Wax For waxing acrylic resin Nonpigmented inlay wax jackets and compression- molded acrylic veneers Wax forms RPD patterns: spiral retention Same characteristics at the posts, sprues, external finish softer inlay lines, etc. Sheet- casting wax Relief to create areas under 24 ga= 0.51mm RPD acrylic resin grinds 26 ga= 0.40 mm 28 ga= 0.32 mm 30 ga= 0.25 mm Sticky wax To hold broken pieces Breaks with a “snap” at room together prior to pouring an temperature; shows very little indexing cast flow when cool  Types of Dental Waxes Material Uses Remarks Utility Wax Beading impressions Tacky at room prior to boxing temperature Boxing Wax Damming impressions Supplied in strips 1 ½ for controlled pouring of inch wide by 12 inch casts long Blockout Wax To block out undercuts Flows easily, sticks to a in RPD fabrication cast well, cuts cleanly Beeswax To seal a refractory cast Use at around 290º F Classifi cation of Dental waxes 1. According to origin Mineral Plant Insect Animal 2. According to use Pattern Wax Processing Wax Impression Wax Inlay casting Boxing Corrective RDP casting Utility Bite registration Baseplate Sticky Carding Shellac 3. A c c o r d i n g t o I S O C l a s s i fi c a t i o n Ty p e 1 ( C a s t i n g w a x ) Class 1 - Soft Class 2 - Hard Ty p e 2 ( B a s e p l a t e w a x ) Class 1 - Soft Class 2 - Hard Class 3 - Extra hard Group of Waxes Dental Waxes fall into three functional groups: 1. Impression 2. Pattern 3. Processing Impression Waxes These waxes are used primarily by the dentist at the chair. They have low melting points and fl ow fairly easily at mouth temperatures. They can be distorted very easily and require extreme care in handling. Examples of impression waxes are corrective wax and jaw movement recording wax.  Pattern Waxes They are used to form the molds in which prosthodontic restorations are made. E x a m p l e s o f p a t t e r n w a x e s a r e i n l ay w a x , b a s e p l a t e w a x , wire wax, preformed w a x , a n d s h e e t - c a s t i n g w a x. W i t h t h e n o t a b l e e x c e p t i o n o f i n l ay w a x , a l m o s t a l l of the pattern waxes are meant to be used in controlled thicknesses. Gauge (ga) is a measure of thickness. The term is applied to the diameters of metal wires and wax form s having circular and semicircular cross sections (for example, wire wax). Gauge is also used when talking about sheet metal and sheet wax thicknesses. U n f o r t u n a t e l y, m a n u f a c t u r e r s d o n ’ t a l w ay s u s e t h e s a m e g a u g e s t a n d a r d. E v e n i f the discussion is limited to wax, the thickness of wax shapes with the same gauge number can vary between two manufacturers. Processing Wax These waxes are used primarily for fabricating prosthodontic restorations. Examples are sticky wax, utility wax, boxing wax, blockout wax and beeswax Baseplate Wax Composition. Baseplate wax is com posed mainly of beeswax, paraffi n, and coloring matter. The ingredients are melted together, cast into blocks, and then rolled into sheets. A typical baseplate wax might contain 50 parts of yellow beeswax, 6 parts of gum mastic, 3 parts of prepared chalk, and 4 parts of vermilion. Requirements. There are several requirements for a baseplate wax. The wax must be fairly rigid at mouth temperature under biting pressure. It must be capable of holding porcelain or acrylic teeth in position, but must not be brittle. The wax should maintain a uniform consistency throughout a normal range of room temperatures as well as at mouth temperature.  Baseplate Wax Ty p e s. B a s e p l a t e w a x i s s u p p l i e d i n t w o t y p e s , hard and medium. The hard wax is indicated for w a r m e r c l i m a t e s b e c a u s e i t r e s i s t s fl o w a t h i g h e r temperatures. At cold temperatures, it might be too brittle and tend to crack. The medium wax is indicated for low temperatures but might exhibit t o o m u c h fl o w i n a w a r m e r e n v i r o n m e n t. Uses. Baseplate wax is used for occlusion rims, as a b o x i n g f o r m a t r i c e s , f o r fi l l i n g t h e tongue space of lower impressions, in complete and partial denture wax-ups, and for m any miscellaneous purposes. Most baseplate wax sheets are about 1 millimeter (mm) (18 gauge [ga]) thick.  Inlay Wax General Composition. I n l ay w a x c o n s i s t s o f p a r a ffi n ( t o m a ke u p t h e b u l k ) ; g u m d a m m a r (to improve the s m o o t h n e s s i n m o l d i n g a n d t o r e n d e r t h e w a x m o r e r e s i s t a n t t o fl a k i n g a n d cracking); and carnuba (to control the softening point and hardness of the wax). Requirements for Use in Dental Procedures. I n l ay w a x i s o n e o f t h e m o s t c a r e f u l l y compounded of all the dental waxes. It should have the following qualities: high accuracy in reproducing every detail of a cavity or crown preparation; ease of carving without chipping or fl a k i n g ; w o r k a b l e in the mouth at body temperature and in the laboratory at room temperature; dimensionally stable when transferred from one temperature environment to another; strong enough in thin areas to withstand the ordinary stresses of i n v e s t i n g ; a n d fi n a l l y, t h e a b i l i t y t o b u r n out cleanly from the mold at ordinary burnout temperatures without leaving a solid residue. Type s of I nlay Wax. Ther e are thre e type s of inlay wax : 1. Type A , a hard or low fl ow wax use d in some indir e ct methods; 2. Type B, for the dire ct te chnique of patte rn making or intraoral use 3. Type C , for the indire ct technique or labor atory use. Ivory Wax Ivory (or White) Wax. Ivory or white wax is an inlay wax containing no color pigment. It is especially useful for waxing acrylic jacket patterns. It does not leave a colored residue in the plaster mold which might discolor the resin of the jacket crown. Casting Waxes for Partial Dentures P r e f o r m e d Wa x ( R o u n d a n d H a l f- R o u n d C r o s s S e c t i o n ). P r e f o r m e d w a x i s s u p p l i e d by the manufacturer in a variety of shapes and sizes suitable for use in constructing the wax pattern for a partial denture framework. Some of the round forms (wire wax) can also be used for spruing fi x e d p r o s t h e t i c u n i t s. I n l ay Wa x. W h e n w a x i n g f r a m e w o r k s , i n l ay w a x i s p r i m a r i l y u s e d t o f r e e fl o w a n d carve t h o s e p a r t s o f t h e p a t t e r n t h a t j o i n p r e f o r m e d c o m p o n e n t s t o e a c h o t h e r. I n l ay w a x i s a l s o u s e d t o sprue patterns. S h e e t - C a s t i n g Wa x. S h e e t - c a s t i n g w a x i s v e r y s i m i l a r t o b a s e p l a t e w a x. At room temperature, sheet-casting wax possesses the properties of toughness and pliability and s u ffi c i e n t t a c k i n e s s t o a d h e r e t o t h e c a s t a n d s t ay w h e r e i t i s placed. Gauge. Sheet-casting wax is manufactured in several thicknesses or gauge. The most common sizes are 24, 26, 28, and 30 gauge. C o l o r. A l t h o u g h m a n u f a c t u r e r s s u p p l y t h e w a x s h e e t s i n s e v e r a l c o l o r s t o distinguish w a x e s o f d i ff e r e n t c o n s i s t e n c i e s a n d h a n d l i n g c h a r a c t e r i s t i c s , t h e r e is no standardization of c o l o r s a m o n g m a n u f a c t u r e r s. Fo r e x a m p l e , o n e b r a n d o f g r e e n w a x m ay b e e n t i r e l y d i ff e r e n t i n working properties from the green wax o f a n o t h e r m a n u f a c t u r e r. U s e s. S h e e t - c a s t i n g w a x c a n b e u s e d w h e n a d e fi n i t e t h i c k n e s s o f w a x i s n e e d e d. Its principal use is with RPD work to provide relief of the residual ridge on the m aster cast. It is often combined with one thickness of baseplate wax to produce a palate of uniform thickness in a complete denture. Sticky Wax Sticky wax is compo se d of be e swax , par affi n, and a conside rable amount of natural r e sin. The re sin give s the wax its adhe sive ne ss and har dne ss. A n important prope rty of sticky wax is that it bre aks unde r pr e ssure inste ad of bending or distor ting. This pr oper ty make s it use ful for joining the par ts of a broke n denture or holding toge the r the str uctur al par ts of a wrought wire clasp while it is inve ste d for so lde r ing. Utility Wax U tility wax is an e x tre me ly pliabl e wax that is marke te d in rope form. I t is plastic and some what tacky at r oom te mpe r atur e, which makes it usable witho ut he ating. Most importantly, utility wax is use d for be ading impre ssions be for e pouring the cast. I t is some time s use d in impr ession te chniques be for e pour ing the cast to build up the impr ession tr ay bor de rs. Boxing Wax Boxing wax is a specially prepared wax, supplied in strips 1 1/2 inches wide by 12 inches long. It is primarily used to box impressions. Most boxing waxes do not require heating; they are pliable enough at room temperature to be formed into desired shapes Low-Fusing Impression Wax Low fusing impression wax is specially compounded to fl ow under controlled pressure in the mouth. It is melted in a water bath and painted on the tissue surface of an individual impression tray as a corrective liner for fi nal complete and RPD impressions. Because the wax is easily distorted, low-fusing wax impressions must be handled with the utmost care. Fingers must never touch the tissue side of the impression, including the periphery. W hen the impression is rinsed, a gentle stream of room temperature water should be used. A separator is not necessary when the cast is poured. Undercut (Blockout) Wax Undercut wax has physical proper ties that allow it to be built up around an abutment tooth and then easily carved with surveying tools. Undercut wax is made by combining beeswax, resin, and kaolin. It is usually supplied in small, wide-mouthed jars. Disclosing Wax Disclosing wax has a very low fusing range. It fl ows readily under pressure and is used to detect points of unequal pressure when seating m any kinds of castings. Disclosing wax is melted on the tissue side of a casting and then held in place under pressure. It fl ows away from the pressure points and discloses them for corrections Beeswax Refi ned beeswax is supplied in cakes or bars. It is used in molten form (280 to 300 o F) as a dip for sealing refractory casts. To prevent cracking, casts must be heated and dehydrated before they are dipped. Subsequent sealing of refractory casts provides a satisfactory surface for attaching wax and plastic patterns, and prevents absorption of moisture when invested for casting RPD frames.