GB412978A - Improvements in or relating to dental prosthesis - Google Patents

Abstract

412,978. Artificial teeth. FISCHER, V. J., 39, Place St. Felix Ó Beziers, HÚrault, France. Dec. 31, 1932, Nos. 36998 and 36999. Convention dates, Dec. 31, 1931 and July 21, 1932. [Class 81 (ii).] Artificial teeth each having a complete shell of gold and a core of ceramic material or light metal are formed by providing cores a, fitted with pins b, with a wax coating of a thickness varying according to the expected wear of the tooth at any point, investing the coated core in a metal casting mould, burning off the wax so as to leave the core suspended by its pins in the cavity in the investing body, as shown in Fig. 7, and then applying a gold coating by casting. The wax control cores are supplied to the dentist, who may add or remove wax as required and may connect several teeth together, using a hot spatula. The cores are set up on a plaster model of the jaw c and are held in place by means of a pad d of clay mixed with glycerine into which the pins are pressed. The projecting portions of the pins, which may be made of stainless steel, are cut off level with the surface of the gold coated teeth and the exposed ends may, if desired, be coated with solder. For the commercial manufacture of the wax coated cores, a number of cores are placed in connected cavities in a two-part mould 1, 2, Fig. 1. Each core carries two pins which pass through corresponding passages in the mould part 2 and one of these pins, which is formed with a bevelled end and a notch, is engaged by a spring-pressed pin 6 so that the core is correctly positioned relative to the walls of the cavity in the mould. Hard wax is then poured into the mould, and after cooling and opening of the mould, the wax coated cores are removed from the mould part 2 by pressing on the externally projecting portions of the core pins by means of a rod with pins entering external recesses on the mould, inserting a plate e, Fig. 3, and lifting off the cores. Reference is made to known constructions wherein an ordinary artificial tooth coated with wax is held in place in a casting mould by means of gold wedges, or an artificial tooth, with or without undercut notches, is coated with gold by electrodeposition.