Jig device and apparatus and method of making a dental prosthesis or pattern therefor

A method wherein a milling machine cuts a prosthesis from a two-sided work piece held in a jig device, said method comprising, in sequence, the steps of

• inserting the jig device holding the work piece into the milling machine at a predetermined location so the jig device and milling machine are in an exact spatial relationship to enable the milling machine to precisely mill from the work piece a prosthesis having a surface essentially free of defects,
• partially milling through a first side of the work piece to form in the work piece a cavity having a surface part corresponding to at least a portion of the prosthesis being made
• removing the jig device from the milling machine and filling the cavity at least partially with a support material,
• presenting to the milling machine a second side of the work piece by inverting the jig device and reinserting the inverted jig device into the machine at said predetermined location,
• milling the work piece from said second side to form said prosthesis with a surface essentially free of defects, said prosthesis being supported within the work piece by the support material, and
• separating the prosthesis from the work piece.

A method of making a prosthesis wherein a milling machine having a planar tabletop and a cutting tool with a longitudinal centerline, said tabletop moving laterally in straight line along a working reference plane in one or the other of orthogonal directions and the cutting tool being mounted to rotate and to move towards and away from the tabletop along a straight line and terminating at a cutting tip that cuts a prosthesis from a work piece held immobile in a jig device having opposed, parallel planar surfaces and locating structure for positioning the jig device in a predetermined location on the tabletop so the cutting tool's longitudinal centerline is normal to the working reference plane and intersects a reference point on the working reference plane, said method comprising the steps of

• positioning the jig device holding the work piece on the tabletop with one of the jig device's planar surfaces next to, and substantially parallel to, the planar tabletop,
• engaging the jig device's locating structure with locating structure on the tabletop so the jig device is in said predetermined location and mounting the jig device to the tabletop so that said jig device moves with the tabletop as said tabletop moves laterally,
• moving the tabletop along straight lines laterally in the working reference plane in one or the other of orthogonal directions and moving the cutting tool from a start position along a straight line following said longitudinal centerline into the work piece and rotating the cutting tool to cut away a substantial portion of material from the work piece while avoiding penetrating through the work piece with the tip of the cutting tool to form in the work piece a cavity having a surface part corresponding to at least a portion of the prosthesis being made,
• discontinuing the lateral movement of the tabletop and returning the cutting tool to the start position,
• removing the jig device from the milling machine and filling the cavity at least partially with a support material,
• inverting the jig device and reinserting the inverted jig device into the machine and positioning and mounting said inverted jig device at said predetermined location to present to the cutting tool an opposite side of the work piece,
• moving the tabletop along straight lines laterally in the working reference plane in one or the other of orthogonal directions and moving the cutting tool from the start position along a straight line following said longitudinal centerline into the work piece and rotating the cutting tool to drill through the opposite side of the work piece to remove the balance of material adjacent the surface part corresponding to at least a portion of the prosthesis being made to form completely a prosthesis having a surface essentially free of defects, said prosthesis being supported within the work piece by the support material, and
• removing the jig device from the milling machine and separating the prosthesis from the work piece and support material.

An apparatus for making a prosthesis from a two-sided work piece, including

• a milling machine having a cutting tool terminating at a cutting tip that has at a start position an exact spatial relationship with respect to a working reference plane of the milling machine,
• a holder for the work piece that inverts the work piece moving the work piece from a first position presenting to the cutting tool a first side of the work piece and to a second position presenting to the cutting tool a second side of the work piece, and
• a drive mechanism for the milling machine that is initially operated when the work piece is in the first position to partially cut through one side of the work piece to drill away a substantial portion of material from the work piece while avoiding penetrating through the work piece with the tip of the cutting tool to form in the work piece a cavity having a surface part corresponding to at least a portion of the prosthesis being made,
• said drive mechanism returning the cutting tool to the start position after partially cutting through said one side of the work piece to enable filling the cavity at least partially with a support material,
• said drive mechanism being operated to completely cut through the opposite side of the work piece after filling the cavity to finish making a prosthesis having a surface essentially free of defects.

An apparatus for making a prosthesis from a two-sided work piece held immobile in a jig device, said apparatus including

• a milling machine with working reference plane having thereon a reference point and a planar horizontal tabletop and a vertically oriented cutting tool mounted over said tabletop, said tabletop and cutting tool each having a start position,
• said tabletop having thereon a locating structure for positioning the jig device in a predetermined location on the tabletop and said cutting tool having a central longitudinal centerline and a cutting tip for cutting the prosthesis from the work piece, said longitudinal centerline intersecting the reference point at a right angle when the tabletop and cutting tool are in the start positions,
• locating structure on the tabletop that enables an operator to insert manually the jig device into the milling machine at a predetermined location so the jig device and milling machine are in an exact spatial relationship to enable the cutting tool to precisely cut from the work piece a prosthesis having a surface essentially free of defects,
• a drive mechanism for the milling machine that moves said tabletop from the start position laterally along a working reference plane in one or the other of orthogonal directions and rotates the cutting tool and moves said cutting tool from the start towards and away from the tabletop along a straight line following said longitudinal centerline,
• said drive mechanism initially operated to partially cut through one side of the work piece to drill away a substantial portion of material from the work piece while avoiding penetrating through the work piece with the tip of the cutting tool to form in the work piece a cavity having a surface part corresponding to at least a portion of the prosthesis being made,
• said drive mechanism returning said tabletop and cutting tool to the start positions after partially cutting through said one side of the work piece so the jig device may be manually removed, inverted and reinserted into the locating structure to locate said jig device in said predetermined location on the planar tabletop and to present to the cutting tool an opposite side of the work piece,
• said drive mechanism being operated to completely cut through the opposite side of the work piece after reinsertion of the jig device to finish making a prosthesis having a surface essentially free of defects.

An apparatus comprising

• a milling machine having a cutting tool terminating at a cutting tip that has at a start position an exact spatial relationship with respect to a working reference plane of the milling machine,
• means for holding a two-sided work piece from which is milled a dental prosthesis essentially free of defects,
• means for presenting to the cutting tool a first side of the work piece and operating the cutting tool to partially cut through the first side to form in the work piece a cavity having a surface part corresponding to at least a portion of the prosthesis being made,
• said holding means enabling the work piece to be inverted after filling the cavity at least partially with a support material to present to the cutting tool a second side of the work piece, and
• means for positioning the cutting tool to overlie the second side opposite the surface part corresponding to at least a portion of the prosthesis being made portion, and
• means for operating the cutting tool to completely cut through the second side of the work piece to form completely a prosthesis with a surface essentially free of defects that is supported within the work piece by the support material.