Program to make of cutting data for inner face of dental prosthesis

A program to make of cutting data for inner face of a dental prosthesis, the program comprising:

• a surface model creating means to create a surface model of a portion, at which a dental prosthesis is mounted, based on three-dimensional data obtained by a three-dimensional measuring device to measure the three-dimensional coordinates (x, y, z) of the shape of a gypsum model including an abutment tooth;
• a cutting direction specifying means to specify a direction of a center shaft of a cutting bar of an automatic cutting machine for cutting a dental prosthesis to be produced, the direction being specified with respect to the surface model;
• and
• a surface model for machining creating means to create a surface model for machining by the steps of:
• adjusting a basic axis (z axis) of the three-dimensional data of the surface model created by the surface model creating means so as to be in parallel with the center shaft of the cutting bar;
• changing the three-dimensional data of the surface model to three-dimensional data having new coordinates by determining plane moving coordinates (X axis and Y axis) of the cutting bar of an automatic cutting machine for cutting a dental prosthesis in a view in which the surface model is seen from the occlusion face side in parallel with the center shaft of the cutting bar, and determining a base axis (Z axis) in the surface model;
• and
• converting the plane moving coordinates of a point which is on the straight line being rectangular to the base axis and crossing the base axis on a cross sectional plane of the changed new three-dimensional data, to be equal to the plane moving coordinates of a point having the highest height from a specified face being rectangular to the base axis at the opposite side of the occlusion face of the surface model, the distance from the base axis to the point on the straight line being shorter than the distance from the base axis to the point having a high height from the specified face.