Dental Impression Materials

1,159,471. Alginate dental compositions. J. C. MORRELL. 12 July, 1966, No. 31190/66. Heading C3U. A composition consists essentially of a mixture of a water-soluble alginate (e.g. Na, K or NH 4 alginate), calcium sulphate, which may be hydrated, from 1-10% by weight of lithium fluoride and, optionally, an inert filler. The fluoride may be a double fluoride with, e.g. NaF, KF or ZnF 2 . Specified fillers are diatomaceous earth (preferred) CaF, CaCO 3 , calcium triphosphate, bentonite, talc, kaolin, aluminium and lead silicates, and water-insoluble metal oxides. Setting retarders may also be present, e.g. Na 2 CO 3 and sodium orthophosphate, metaphosphate or (preferred) pyrophosphate, and also acid neutralizers which are water-insoluble basic metal oxides, hydroxides and carbonates, preferably MgO.