Chapter 16: Composition and Properties of Dental Waxes

DLA 1201, exam 2

1. Composition and Properties of Dental Waxes Chapter 16

2. Dental Waxes Composed of a mixture of components from natural and synthetic sources Natural waxes are produced from palnts , used in carnauba wax; insects, used in beeswax; and minerals, used in paraffin and ceresin wax Contribute properties to the wax, but are rarely used in their pure form They are combined or mixed with synthetic waxes, gums, fats, oilts , resins and coloring agents.

3. Dental Waxes Components of the waxes allow them to be Sticky Solid Liquid Depending on the temperature

4. Important Properties of Waxes Melting range Flow Excess residue Thermal expansion

5. Melting Range Range of temperatures at which each component of the wax will start to soften and then flow Lower melting points will soften first; then, as the temperature is increased, more components will soften and the wax will eventually flow and become liquid or vaporize Wax is unstable Must be careful to prevent its distortion Controlling temperature allows operator to control viscosity and flow Flame source is neede d if flowable state is desired 5

6. Flow Movement of wax as molecules slip over each other As the temperature increases, the viscosity decreases until the wax becomes liquid If a wax were capable of flow at room temperature, it would be very difficult to control If you’re using the wax for wax bite registration, you would not want it to flow at room temperature, but you would also not want the melting range to be much higher than mouth temperature. If you’re using wax in the lab to box an impression, it is much more desirable to mold the wax, using the heat of your hands or warm water, rather than a flame Different waxes have different properties and uses.

7. Excess residue It is important that all wax be removed from the object onto which its melted If excess residue remains after the wax is removed, this may result in inaccuracies in the object being produced.

8. Thermal expansion Waxes expand when heated and contract when cooled Thermal expansion and contraction of waxes is greater than that of any other dental material Especially important for pattern waxes If wax is heated too far above the melting range or is heated unevenly, expansion above the acceptable standards will result If waxes are allowed to stand, dimensional changes occur from the release of residual stress Wax patterns should be invested within minutes of carving

9. Classification of Waxes Three classifications : Pattern waxes Processing waxes Impression waxes Manufacturers produce these waxes in several forms: Sticks, sheets, blocks, and tins are used 9

10. Pattern Waxes Used in the contruction of metal castings and bases for dentures Three types of PATTERN WAXES Inlay wax Casting wax Baseplate wax 10

11. Pattern Wax- Inlay Inlay waxes are used to prepare patterns for metal casting through the lost wax technique. They may be used directly in the mouth (type I), placed onto the prepared tooth in the direct waxing technique, or, more frequently, melted onto a die outside the mouth in the indirect technique (type II).

12. Pattern Wax- Casting Casting waxes are used to construct the metal framework of partial and complete dentures. These waxes come in sheets and preformed shapes. The physical properties of casting waxes are similar to those of inlay waxes, with the exception of melting range.

13. Pattern Wax--Baseplate Baseplate wax is used mainly to make occlusion rims and to hold artificial teeth to baseplates during the fabrication of dentures. Baseplate wax is composed mainly of beeswax, paraffin, and coloring matter, which are mixed together, cast into blocks, and rolled into sheets.

14. Processing Waxes Used primarily to aid in dental procedures both clinically and in the laboratory Three Types of Processing waxes Boxing wax Used to form a box around impressions of the mouth when a cast is made Utility wax Comes in long ropes that are easily manipulated at room temperature May be used with boxing wax to aid in the pouring of an impression Sticky wax Comes in orange sticks that at room temperature are hard and brittle, but when heated under flame become soft and sticky 14

15. Processing Wax- Boxing The boxing wax limits the flow of the stone/gypsum material. Boxing wax usually is issued in red strips measuring 1½ inches wide, 12 inches long, and 1/8 inch thick. Boxing wax is soft and pliable enough at room temperature to be formed into a desired shape without heating.

16. Processing Wax-Utility Utility wax is used to provide rim locks and otherwise to adapt impression trays for individual impressions, to build up post-dam areas on impressions, and to form a bead or border on preliminary and final impressions. Can also be used to block out undercuts around teeth or tissues prior to impression making, to prevent the impression from locking in place AKA periphery wax Utility wax is pliable enough at room temperature to be used without heating. Utility wax normally is issued in long ropes and usually is red . Clear utility wax is used to cover orthodontic brackets

17. Sticky wax- processing Sticky wax has the property of adhering components of m etal, gypsum or resin together temporarily during fabrication or repair Hard and brittle at room temperature Heated under flame to become soft It is composed of beeswax, paraffin, and resins.

18. Impression Wax Thermoplastic materials used to obtain impressions of the oral structures When heated, they become soft Able to take on a new form in the mouth When cooled, they harden and can be removed

19. Impression wax Corrective impression wax used in conjunction with other impression materials in the process of taking edentulous impressions. This wax flows at mouth temperatures and is used to correct undercuts, to fill small voids, or to help develop a functional posterior palatal seal for complete dentures Bite registration wax used to produce wax bite registrations for articulation of models. The preformed horseshoe shapes often are reinforced with metal particles to provide stability . Susceptible to distortion at temperatures only slightly higher than the mouth and must be carefully monitored 19

20. Manipulation of Waxes Softening of wax should be done: Evenly in dry heat With warm hands With a warm water bath By flame Rotated above so that it evenly softens or flows Melted wax should be added in layers Store waxes at or slightly below room temperature to avoid distortion 20

21. Lost Wax Technique Primary steps to the lost wax and casting procedure are as follows: Pouring the die An exact impression of the prep is first obtained and poured into a high-strength die stone forming the die Waxing the die A detailed wax pattern of the restoration is carved on the die including all anatomy, contours, occlusion, and proximal contacts Spruing the die A wax or plastic sprue is attached to the pattern to form the channel into which the molten metal will be forced Attaching the sprue base The sprue is attached to the sprue base; this forms the funnel to help guide the flow of molten metal into the wax pattern. 21

22. Lost Wax Technique Investing the wax pattern The pattern and attached sprue are encased in an investment ring into which gypsum-based investment is poured Burning out the wax Once hardened, the sprue base is removed and the investment-enclosed pattern and sprue are heated in a burnout oven at high temperatures (500-700ºC), causing the wax and the sprue to vaporize (lost wax), leaving an impression of the wax pattern in the now-empty space Casting the restoration The molten metal is moved by centrifugal force through the empty channel formed by the sprue and into the empty wax patter space Final steps The metal cools, the sprue is removed, and the casting is cleaned and polished

23. Lost Wax Technique Artisans have used the lost wax technique for several hundred years. In the 1500s, artisans, in conjunction with medical practitioners, invented a method for casting gold for dental restorations in molds; today’s techniques are much the same. https:// youtu.be/LinG4dZilxw