Dental cements have a variety of uses and properties, upon which the American Dental Association and International Standards Organization have classified them. Type I cements are considered luting agents, which hold a cast restoration (such as a crown, bridge or veneer) to a tooth. Type II cements are used to restore teeth. Type III cements--called liners and bases--are placed within a cavity preparation, according to "Torres and Ehrlich Modern Dental Assisting."
Glass Ionomer Cement
Glass ionomer cement can be used to attach metal restorations and brackets used in braces to teeth. It can be supplied in bottles of powder and liquid, which are mixed on a glass slab or paper pad using a spatula. The liquid in glass ionomer cement contains itaconic acid, tartaric acid, maleic acid and water. The powder includes zinc oxide, aluminium oxide and calcium. Fluoride, which helps prevent tooth decay, slowly is released from this powder because of its special combination of glass, ceramic particles and a glassy matrix.
Composite Resin Cement
Composite resin cement can be used to attach ceramic or resin inlays and onlays (which are cavity restorations), veneers or metal restorations to teeth and also can be used for bands and brackets in braces. Composite resin cements have properties similar to those of composite resins, which are tooth-coloured materials used for fillings. Composite resins contain quartz (a hard rock-forming mineral), glass, silica (a white colourless crystalline compound) and colourants.
Zinc Oxide-Eugenol Cement
Zinc oxide-eugenol cement can be used to temporarily or permanently cement cast restoration or appliances. The liquid in zinc oxide-eugenol cement (also called ZOE cement) includes eugenol, water, acetic acid, zinc acetate and calcium chloride. The powder has zinc oxide, magnesium oxide and silica. The eugenol in the liquid has a soothing effect on the pulp (the portion of the root---which is the part of the tooth embedded in the jawbone---that contains nerves and blood vessels). That's why ZOE cement is preferred for patients who might have tooth sensitivity following a cavity filling procedure.
Intermediate restorative material (or IRM) is a reinforced ZOE composition with improved strength, and it can be used to restore children's teeth, for restorative emergencies or as part of a program to manage cavities.
Polycarboxylate cement can be used to permanently attach cast restorations, stainless steel crowns and bands for braces. The liquid in polycarboxylate cement consists of polyacrylic acid, itaconic acid, maleic acid, tartaric acid and water. The powder is made up of zinc oxide. The cement, like ZOE, is soothing to the pulp. It's also less irritating to the pulp than is zinc phosphate cement.
Zinc Phosphate Cement
Zinc phosphate cement can be used to permanently cement crowns, inlays, onlays and bridges. Zinc phosphate cement also can be used in deep cavity fillings. The liquid includes 50 per cent phosphoric acid in water, along with aluminium phosphate and zinc salts to control its acidity. The powder has 90 per cent zinc oxide and 10 per cent magnesium oxide. The phosphoric acid can irritate the pulp when used in a cavity preparation. For this reason, another material must be placed under it (such as a liner, sealer or desensitiser).
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