GB776501A - Improvements in or relating to dental impression materials - Google Patents

Abstract

A dental impression material having an alginate base contains indicators which change colour when the material is formed into a paste with water, due to the variation of the pH value of the material, so as to indicate periods during which mixing and transfer to a holder should be carried out and to indicate when setting of the material commences. The indicators may be selected from nitro derivatives of benzene or phenol, thymolphthalein, alizarin yellow R, phenolphthalein, Pa naphtholphthalein, tropeolin, cresolphthalein, or thymol blue. In an example the composition comprises in percentages by weight: .Trisodium phosphate.2 to 6 .Borax.0,2 to 0,6 .Sodium carbonate.0,2 to 1 .Sodium alginate.10 to 20 .Inert excipient.50 to 70 .Calcium sulphate.15 to 30 .Thymophthalein.0,01 to 0,03 .Phenolphthalein.0,005 to 0,015 .Aromatizers.Small trace Upon mixing with water this composition is initially blue-violet and changes to pink at the end of the period available for mixing, and the beginning of the period available for transfer to a holder and insertion in a patient's mouth. The end of the latter period is indicated when the mixture becomes white, at the commencement of setting.