(1) Powder. The powder is composed of 80 percent zinc oxide and 20
percent polymethyl methacrylate.
Liquid. The liquid is 99 percent eugenol and 1 percent acetic acid.
b. Dispensing. The first step in dispensing IRM is to fluff the powder for
uniform density. The measuring scoop is then filled, but not packed, with powder and
leveled with the spatula. The powder is then placed on the mixing pad. Finally, one
drop of liquid is added for each level scoop of powder (at a 1 to 1 ratio). After using the
c. Mixing. Spatulate quickly with a stainless steel spatula, combining half the
powder with all the liquid. Add the remaining powder in 2 or 3 increments and spatulate
thoroughly. The mix will be stiff and should be stropped (whipped vigorously) each time
with the spatula for 5 to 10 seconds. This type of mixing results in a smooth and
adaptable working consistency. Mixing the IRM should be completed in approximately
1 minute (60 seconds).
Section II. MISCELLANEOUS DENTAL MATERIALS
Calcium hydroxide is used in operative procedures such as pulp capping
(protection for an exposed or nearly exposed pulp). It is available in premixed
commercial preparations ready for immediate use. Because of its low crushing
strength, calcium hydroxide alone is not used as an intermediate base. It is usually
covered with zinc phosphate cement or zinc oxide and eugenol cement. Dycal, a
commercial preparation, is an example of calcium hydroxide.
ROOT CANAL FILLING MATERIALS
Root canal filling materials consist of tapered gutta-percha or silver points in
standard sizes that match the size of the files used. The points are cemented in place
with root canal sealer that is usually a zinc oxide and eugenol preparation. Root canal
filling materials are used to fill previously prepared root canals. They are a part of root
canal, or endodontic, therapy.
a. General. Gutta-percha points are made from the refined, coagulated, milky
exudate of trees in the Malay peninsula. Gutta-percha is pink or gray in color. It is
softened by heat and is easily molded. When cool, gutta-percha maintains its shape.
Gutta-percha points are used as a root canal filling material.