Process for the Manufacture of Tooth Parts from Dental Grade Metal Powder

Abstract

When producing tooth replacements from metal, the conventional method of casting is almost exclusively employed, even though said method is a relatively complicated one. The object of the invention is therefore to make available a method that is considerably simpler. In this method, an aqueous suspension, still containing microcrystalline wax and ethoxylated alcohols, is generated with the dental-grade metal powder. The metal powder is deposited on a model by electrophoresis, resulting, for example, in the formation of a cap ( 4 ). This cap ( 4 ) is filled with investment compound ( 5 ) and placed on a firing support ( 6 ), where it is sintered in this position. A cap is obtained which, in terms of its strength characteristics, is the equal of a cap that has been produced by casting. Alternatively, the cap ( 4 ) can be stabilized, during sintering, on a plated stump or in a muffle filled with a temperature-resistant powder.

1 . Process for the manufacture of tooth parts from dental grade metal powder, characterized by
 the fact that a metal powder layer is deposited from a suspension liquid onto a model ( 1 ) by means of electrophoresis, whereby this metal powder layer has the shape of the desired tooth part ( 4 ), and the tooth part ( 4 ) is stabilized for the sintering process by way of the following steps:
 a) it is affixed to a firing support ( 6 )
 or 
 
 b) it remains on a duplicated model
 or 
 
 c) it is placed in a muffle that has been filled with embedding material or temperature-resistant powder. 
   
     
     
         2 . Process in accordance with  claim 1 , characterized by the fact that the suspension liquid comprises 30-60 wt % of microcrystalline wax, 5-10 wt % of ethoxylated alcohols with more than 14 C atoms, and 30-60 wt % of water. 
     
     
         3 . Process in accordance with  claim 2 , characterized by the fact that the model is coated with a release layer. 
     
     
         4 . Process in accordance with  claim 3 , characterized by the fact that a conductive layer is applied to the release layer. 
     
     
         5 . Process in accordance with  claim 4 , characterized by a particle size of the metal powder of 1-10 μm. 
     
     
         6 . Process in accordance with  claim 5 , characterized by the fact that electrophoresis is carried out at 30-40 V. 
     
     
         7 . Process in accordance with  claim 6 , characterized by the fact that electrophoresis is carried out at 20-90 mA. 
     
     
         8 . Process in accordance with  claim 7 , characterized by gold as the basic metal for the dental grade metal powder. 
     
     
         9 . Process in accordance with  claim 8 , characterized by the fact that the tooth part is a cap ( 4 ) or a bridge. 
     
     
         10 . Process in accordance with  claim 9 , characterized by the fact that sintering is carried out under vacuum and/or the metal powder is coated with an oxidation stopping lacquer. 
     
     
         11 . Process in accordance with  claim 10 , characterized by the fact that sintering takes place in a protective gas. 
     
     
         12 . Process in accordance with  claim 11 , characterized by the fact that the temperature-resistant powder comprises a mixture that comprises a metal oxide and an oxygen consuming powder. 
     
     
         13 . Process in accordance with  claim 12 , characterized by the fact that use is made of a mixture that comprises alumina powder and graphite powder.