Process and apparatus for preparing a crown portion to be fixed on a tooth

An apparatus for use in preparing a dental crown portion to be secured to a tooth stump, said apparatus using a numerically controlled processing machine and comprising:

• a clamping device on said processing machine for a model of a group of teeth containing a tooth stump or for a model of a tooth stump;
• a scanning head on said processing machine for generating position data;
• a guiding means on said processing machine for guiding the scanning head along said model;
• a computer memory connected to said scanning head for storing position data generated when the scanning head is guided along the model;
• and
• a contour tool on said processing machine controlled by said memory and movable relative to said model.

Apparatus for the preparation on a blank of a copy from an original object comprising:

• a numerically controlled processing machine having a scanner for generating position data of the surface of the original object;
• an electronic control device having a memory for storing said position data;
• and
• a processing tool connected to said electronic control device and guided along a blank in accordance with the stored position data to reproduce the surface of the original object.

A process for producing from molding material on a tooth stump model a casting model for a dental crown, said casting model having a specified minimum thickness over all parts of the tooth stump model comprising:

• fixedly mounting the tooth stump model relative to a numerically controlled processing machine;
• scanning at least part of the surface of the tooth stump model to acquire data characteristic of the surface contour of the tooth stump model with a scanning head on said processing machine;
• storing said data in a computer memory coupled to said machine;
• applying a molding material to the tooth stump model;
• and
• moving a contouring device on said processing machine to form a casting model from said molding material using said stored data from said computer memory to control said contouring device.

An apparatus for use in producing a casting model or a dental crown portion for a tooth stump for which a tooth stump model has been made comprising:

• means for generating data indicative of the contour of the surface of the tooth stump model;
• computer means coupled to said means for generating data for storing said generated data and for calculating from said stored data the outer contour of a dental crown or a casting model;
• a contouring device movable relative to said tooth stump model;
• and
• means coupled to said contouring device for moving said contouring device relative to the tooth stump model, said means coupled to and cooperating with said computer means so that material placed on said tooth stump model is formed by said contouring device according to said calculated outer contour into a dental crown or casting model.