GB261447A - Improvements in or relating to dentures - Google Patents

Abstract

261,447. Kropman, S. M., and Horowitz, P. July 14, 1925. Teeth, artificial.-A material for use in making dentures is prepared by condensation of phenol and 40 per cent formaldehyde in equal parts by volume with a small quantity of a condensing agent, such as 2 to 3 per cent of hydrochloric acid of 33 per cent strength, or 4 to 6 per cent of concentrated sulphuric acid or of oxalic acid, the reaction being carried out at a temperature of 65 to 70‹ C. and interrupted at a point such that the product is solid at ordinary temperatures but becomes plastic on heating in the process of packing the dental mould. Various specified dyes or pigments may be added prior to or during the reaction or may be added to the product. The material may be moulded in an ordinary plaster of Paris mould and hardened by the ordinary process employed for vulcanizing rubber, and may be used in combination with rubber, for instance as a gum facing, the vulcanization of the rubber and the hardening of the condensation product proceeding simultaneously. The material may also be used in combination with metal, or a plate formed of the condensation product may be coated with rubber. The nature of the material is such that it may be used for taking the bite prior to the final hardening. To prevent hardening during storage the material may be covered with a protective film of wax, or of a solution of collodion or rubber in chloroform, which is removed before use. Reference has been directed by the Comptroller to Specifications 1921/08, [Class 2, Acids and salts, Organic &c.], and 153,494, [Class 2 (iii), Dyes &c.].