dental02.jpg (11342 bytes)Fundamentals of
Dental Materials

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Dental Resins, Miscellaneous Dental Materials, and Dental Gold/Alloys

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Intermediate restorative material (IRM) is a zinc oxide and eugenol cement that has been reinforced for increased strength. It is used as an intermediate base beneath a metallic restoration and also as a temporary restoration.

a. Composition.

(1) Powder. The powder is composed of 80 percent zinc oxide and 20 percent polymethyl methacrylate (the powder used for acrylic resin).

(2) 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 liquid, immediately recap to prevent evaporation and contamination.

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).

David L. Heiserman, Editor

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Revised: May 22, 2017