Many different waxes are used in dentistry. The composition, form, and color of each wax are designed to facilitate its use and to produce the best possible results. The discussion in this lesson is limited to aspects of clinical interest.
a. Inlay wax is used to prepare patterns. These patterns are reproduced in gold or other material in the fabrication of inlays, crowns, and fixed and removable partial dentures. Inlay wax is sometimes called casting wax.
b. Properties. For success in these procedures, the wax must have properties which will enable very close adaptation to the prepared portions of the tooth to be restored, must provide freedom from distortion, must permit detailed carving without flaking or chipping, and must not leave excessive residue when it is removed from a mold by burning. The wax should harden at body temperature but soften at a temperature low enough to permit it to be manipulated in a plastic state in the mouth without injury to pulp or oral tissues. Its color should contrast with the colors of teeth and oral tissues to facilitate carving, except that ivory wax is used to avoid risk of color contamination when porcelain or acrylic restorations are constructed. Because of the importance of certain qualities of these waxes, the ADA has developed certain specifications with which an inlay wax must comply to be acceptable.
c. Usage. Inlay wax is available in blue, green, ivory, or deep purple sticks, in preformed shapes for partial dentures, and in solidly packed cans. It is hard at room temperatures and breaks if bent sharply. This wax remains hard at mouth temperature and may be carved either in or out of the mouth. It is softened with dry heat or by immersion in warm water until pliable.
a. Baseplate wax is used mainly for making occlusion rims and for holding artificial teeth to baseplates during the fabrication of dentures.
b. Properties. Baseplate wax is composed mainly of beeswax, paraffin, and coloring matter, which are mixed together, cast into blocks, and rolled into sheets. The sheets are red or pink, 3 inches wide and 6 inches long. Baseplate wax is relatively hard and slightly brittle at room temperature but becomes soft and pliable when heated.
c. Usage. Baseplate wax must be capable of holding porcelain or acrylic teeth in position both at normal room temperature and at mouth temperature.
d. Two Types. There are two types of baseplate wax, hard and medium, listed in the Federal Supply Catalog. The hard type is suitable for use in warm climates but tends to crack and flake at low temperatures. The medium type is suitable for use at low temperatures but flows excessively at high temperatures.
a. Sticky wax has many uses in a dental clinic and dental laboratory. It holds broken pieces of a denture together and assembles components of fixed partial dentures and wrought partial dentures in preparation for soldering.
b. Properties. Sticky wax becomes sticky when melted and has the property of adhering to the surfaces of various materials. Sticky wax is composed of beeswax, paraffin, and resins. It is usually supplied as hexagonal sticks of various colors, often orange or purple. It is brittle at room temperature and assumes a thick liquid consistency when heated.
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. Utility wax is pliable enough at room temperature to use without heating. Utility wax is normally issued in stick form and is usually red in color. When it is supplied in rope form, it is sometimes called rope wax.
Disclosing wax is used to determine unequal pressure points in a denture that may cause discomfort to the patient. These points are located by painting the wax on the tissue side of the denture base and holding the denture in place under pressure in the mouth. The wax flows away from the points needing relief. Disclosing wax is sometimes known as pressure indicator paste.
Boxing wax is used to form a box around impressions of the mouth when making a cast (model). The boxing limits the flow of either plaster of Paris or artificial stone gypsum material. Boxing wax is usually issued in red strips measuring 1 1/2 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. For further softening, a strip of wax can be passed through an open flame.
LOW-FUSING IMPRESSION WAX
Low-fusing impression wax is a wax that is especially compounded so that when subjected to controlled pressure it will flow to some extent in the mouth. Its main ingredient, spermaceti, is obtained from the head of the sperm whale. Low-fusing impression wax is often used in relining or rebasing complete and partial dentures. Because it is easily distorted, impressions must be handled with care. Boxing is not recommended, and separators are not necessary when pouring the cast.
|David L. Heiserman, Editor||
Copyright © SweetHaven
Revised: June 06, 2015