Patent ID: 7454843
Filing Date: 2008-11-25
Classification: A61C,G01B

Abstract:
1. A method of producing three-dimensional shape data of a dental prosthesis for cutting a block to form the dental prosthesis by an automatic cutting machine to have a same shape as that of a measured object, by using the three-dimensional measuring device comprising: a rotary table having a rotating shaft, and an axis of the rotating shaft is a first axis, a table, including a placing table to fixedly provide a measured object mounting tool on an upper part thereof, wherein the table is movable in directions along a second axis and a third axis and is arranged on the rotary table, and a measuring part to measure three-dimensional coordinates of a shape of a measured object mounted on the measured object mounting tool on the placing table by one laser sensor rotationally moving in a plane containing the first axis around a desired point on the first axis and moving in a direction parallel to the first axis, wherein said method of producing comprises: preparing a model of the dental prosthesis, which is the measured object, wherein said model of the dental prosthesis has an engaging portion projected on a jawbone side which has a projected and/or recessed engaging part having a cross sectional shape other than that of a rotary body; preparing the measured object mounting tool; engaging the engaging part of the engaging portion of the model of the dental prosthesis with a mounting part of the measured object mounting tool; placing the measured object mounting tool with the model of the dental prosthesis on the placing table; rotating the rotary table around the first axis to keep laser light irradiated from the laser sensor of the measuring part in parallel with an upper face of a cylindrical part of the measured object mounting tool; moving the laser sensor in the direction parallel to the first axis via the measuring part so as to transfer a portion irradiated by the laser light to a position of a height before reaching a top of a pillar part from a side face of the cylindrical part of the measured object mounting tool passing through an inclined part of the measured object mounting tool and then rotationally moving the laser sensor to thereby measure received light amounts of the laser light from the cylindrical part and the pillar part of the measured object mounting tool and the model of the dental prosthesis, and the three-dimensional coordinates of shapes thereof; detecting a position where the received light amount of the laser light is remarkably decreased when transferring from the side face of the cylindrical part of said measured object mounting tool to the inclined part; detecting a coordinate on the first axis of a position of a lower end of the inclined part of the measured object mounting tool; calculating a coordinate on the first axis of a position of an upper end of the engaging portion of the model of the dental prosthesis based on a prememorized distance along the first axis between the position of the lower end of the inclined part of the measured object mounting tool and the position of the upper end of the engaging portion of the model of the dental prosthesis, wherein the model of the dental prosthesis is provided on the measured object mounting tool; and extracting only the three-dimensional coordinates of the shape other than the engaging portion of the model of the dental prosthesis positioned on an upper side of the coordinate calculated from the measured three-dimensional coordinates, so that said three-dimensional shape data of the dental prosthesis for cutting the block to form the dental prosthesis by the automatic cutting machine is produced by carrying out said method in order, wherein an engaging portion of the dental prosthesis has approximately a same shape as the engaging portion of the model of the dental prosthesis.