Method and apparatus for the fabrication of custom-shaped implants

• US 4,575,805 A
• Filed: 08/23/1984
• Issued: 03/11/1986
• Est. Priority Date: 12/24/1980
• Status: Expired due to Term

• Current Assignee: Sirona Dental Systems GmbH (Sirona Dental Systems Incorporated)
• Original Assignee: Marco Brandestini, Werner H. Moermann
• Inventors: Brandestini, Marco, Moermann, Werner H.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/643,755
• Time in Patent Office: 565 Days
• Field of Search: 364/168, 364/474, 364/475, 364/414, 356/355, 356/356, 356/357, 356/358, 356/374, 356/376, 356/378, 356/2, 250/237 G, 382/59, 382/65, 382/68, 33/174 D, 128/776, 433/55, 433/68, 433/73, 433/204, 433/213, 433/214, 433/223
• US Class Current: 700/163
• CPC Class Codes: A61C 13/0004 Computer-assisted sizing or machining of dental prostheses
• CPC Class Codes: A61C 19/04 Measuring instruments specially adapted for dentistry A61C5/44 takes precedence; testing vitality of teeth A61B5/0534; radiation diagnosis specially adapted for dentistry A61B6/51
• CPC Class Codes: A61C 9/006 projecting one or more stripes or patterns on the teeth
• CPC Class Codes: A61F 2/30942 for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
• CPC Class Codes: A61F 2002/30952 using CAD-CAM techniques or NC-techniques
• CPC Class Codes: G05B 19/4207 in which a model is traced or scanned and corresponding data recorded
• CPC Class Codes: G16H 20/40 relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture
• CPC Class Codes: Y10T 29/49567 Dental appliance making

Abstract

The surface characteristics of an organ that needs restoration, for example, a tooth which has been prepared for an inlay insertion, are read by means of a noncontact scan-head. The three-dimensional shape parameters of the implant required to restore the tooth in function and appearance are computed on the basis of the recorded contour data. These parameters are then used in a program sequence which controls a milling, cutting or erosive process in order to manufacture the restorative inlay while the patient waits.

Claims

1. A method for facilitating the fabrication of a workpiece to be placed onto a light reflective object having a three dimensional contour thereon to which said workpiece is to be conformed, comprising the steps of:

noncontact topographic scanning of said contour on said object, including the step of directing a predetermined intensity pattern of light onto said contour so that a corresponding intensity pattern of light will be reflected therefrom, the varying intensity pattern of said reflected light being a measure of said three dimensional contour on said object;

directing said pattern of said reflected light from said object onto a light sensing means;

converting said pattern of light on said light sensing means into a corresponding pattern of electrical data;

selecting a set of said electrical data;

storing said set of said electrical data;

mounting said workpiece onto a machining means which is responsive to electrical data sequentially presented thereto;

sequentially presenting said stored set of electrical data to said machining means; and

machining said workpiece into a three dimensional shape in accordance with said stored set of data.

2. The method according to claim 1, wherein said object is a human tooth and said three dimensional contour is a cavity therein.

3. The method of claim 1, wherein said noncontact topographic scanning is done optically.

4. The method according to claim 1, including after said storing step and prior to said sequentially presenting step the step of modifying said stored set of said electrical data.

5. The method according to claim 1, including prior to said scanning step the step of applying to said contour on said object a coating of a glarefree, reflective substance.

6. The method according to claim 1, wherein said step of directing said predetermined intensity pattern onto said contour includes the steps of:

causing said predetermined intensity pattern to travel toward said contour in a first direction and said pattern of reflected light to travel away from said contour in a second direction oriented at an angle to said first direction;

using as said predetermined intensity pattern a pattern of light which includes alternating bright and dark regions uniformly spaced in a third direction extending perpendicular to said first direction and parallel to a plane containing said first and second directions, said contour causing portions of said bright and dark regions to be spatially shifted in said reflected pattern of light in a fourth direction extending perpendicular to said second direction and parallel to said plane containing said first and second directions; and

selecting the width of each said dark region between adjacent said bright regions of said predetermined intensity pattern to be greater than the difference between the maximum and minimum amounts of spatial shift caused by respective points on said contour which are spaced the maximum possible distance from each other in said second direction; and

wherein said converting step includes the step of causing said light sensing means to measure the average light intensity of portions of said pattern of reflected light in each of a plurality of predetermined and stationary window regions which are uniformly spaced from each other in said fourth direction and which each have a predetermined width in said fourth direction, the intensity measured in each said window region being proportional to the actual physical position in said second direction of a corresponding portion of said contour.

7. An apparatus for facilitating the fabrication of a workpiece to be placed onto a light reflective object having a three dimensional contour thereon to which said workpiece is to be conformed, comprising:

housing means;

light source means on said housing means and first directing means for directing the light from said light source means toward said contour;

optical plate means on said housing means interposed in the path of said light from said light source means for controlling the magnitude of said light so as to facilitate an illumination of said contour with a predefined intensity pattern, said light being reflected in a corresponding intensity pattern indicative of said three dimensional contour on said object;

second directing means on said housing means in the path of said reflected light from said contour for directing said reflected light to a desired location within said housing means;

light sensing means located at said desired location for converting said intensity pattern of reflected light into a corresponding pattern of electrical data;

contour memory means, and means for storing a selected set of said electrical data in said contour memory means;

machining means for machining a workpiece in accordance with a set of electrical data sequentially presented thereto; and

sequencing means for sequentially presenting said selected set of said electrical data to said machining means to cause a machining of said workpiece to a shape corresponding to said contour to enable the shaped workpiece to be fittingly placed onto said contour.

8. The apparatus according to claim 7, wherein said housing means is elongate and at least one end of said housing means is adapted to be received in the mouth of a human;

and

wherein said light from said light source means is emitted from said one end of said housing and said reflected light enters said one end of said housing.

9. The apparatus according to claim 8, wherein said second directing means includes lens means, wherein said light source means is located between said optical plate means and said lens means and is on a side of said lens means remote from said light sensing means.

10. The apparatus according to claim 9, wherein said housing means includes a mirror intermediate said lens means and said optical plate means as well as intermediate said light source means and said optical plate means, said mirror being oriented in the paths of said light emitted from said light source means and said reflected light.

11. The apparatus according to claim 7, wherein aid first directing means causes said predetermined intensity pattern to travel toward said contour in a first direction and to be reflected toward said second directing means in a second direction which is oriented at an angle to said first direction;

wherein said predetermined intensity pattern includes alternating bright and dark regions uniformly spaced in a third direction extending perpendicular to said first direction and parallel to a plane containing said first and second directions, said contour causing portions of said bright and dark regions to be spatially shifted in said reflected pattern of light in a fourth direction extending perpendicular to said second direction and parallel to said plane containing said first and second directions, the width of each said dark region between adjacent said bright regions of said predetermined intensity pattern being greater than the difference between the maximum and minimum amounts of spatial shift caused by respective points on said contour which are spaced the maximum possible distance from each other in said second direction; and

wherein said light sensing means includes means for measuring the average light intensity in each of a plurality of predetermined and stationary window regions which are uniformly spaced from each other in said fourth direction and which each have a predetermined width in said fourth direction, the intensity measured in each said window region being proportional to the actual physical position in said second direction of a corresponding portion of said contour.

12. The apparatus according to claim 7, including an aperture member disposed in the path of said light from said light source and having spaced first and second holes therethrough, said first directing means causing said light from said light source to pass through said first hole and said second directing means causing said light reflected from said contour on said object to pass through said second hole.

13. The apparatus according to claim 12, wherein said optical plate means is located between said light source and said aperture member.

14. The apparatus according to claim 13, wherein said light sensing means includes a sensor having a plurality of sensor elements arranged in a plurality of parallel rows, wherein said optical plate means includes a translucent plate having a plurality of opaque, spaced, parallel rulings thereon, and wherein light passing between two said rulings on said plate, after being reflected by said contour on said object, strikes said sensor in the region of a respective row of said sensor elements thereon.

15. The apparatus according to claim 13, wherein said housing means has means defining a reference surface thereon in the region of an object being scanned and adjacent the path of light directed by said first directing means toward said contour on said object, a portion of said predetermined intensity pattern striking and being reflected by said reference surface and forming a portion of said reflected intensity pattern directed onto said light sensing means.

16. The apparatus according to claim 13, including an image-forming lens disposed adjacent said aperture member on a side thereof remote from said light source, wherein light traveling from said light source to said object passes through said image-forming lens and reflected light traveling from said object to said light sensing means travels through said image-forming lens, said image-forming lens being part of said first directing means and part of said second directing means.

17. The apparatus according to claim 16, wherein said first directing means includes condensing lens means disposed between said light source means and said aperture member and a first prism supported on said housing on a side of said image-forming lens means remote from said light source means for directing light from said image-forming lens means toward said object;

and wherein said second directing means includes said first prism being adapted to direct light reflected from said object toward said aperture member, and includes a second prism which is located on a side of said aperture member remote from said first prism and directs light passing through said second hole in said aperture member toward said light sensing means.

18. An apparatus for facilitating the fabrication of a workpiece to be placed onto a light reflective object having a three-dimensional contour thereon to which said workpiece is to be conformed, comprising:

housing means;

light source means on said housing means and first directing means for directing the light from said light source means toward said contour;

optical plate means on said housing means interposed in the path of said light from said light source means for controlling the magnitude of said light so as to facilitate an illumination of said contour with a predefined intensity pattern, said light being reflected in a corresponding intensity pattern indicative of said three-dimensional contour on said object;

second directing means on said housing means in the path of said reflected light from said contour for directing said reflected light to a desired location within said housing means;

light sensing means located at said desired location for converting said intensity pattern of reflected light into a corresponding pattern of electrical data;

contour memory means, and means for storing a selected set of said electrical data in said contour memory means;

machining means for machining a workpiece in accordance with a set of electrical data sequentially presented thereto;

sequencing means for sequentially presenting said selected set of said electrical data to said machining means to cause a machining of said workpiece to a shape corresponding to said contour to enable the shaped workpiece to be fittingly placed onto said contour;

an aperture member disposed in the path of said light from said light source and having spaced first and second holes therethrough, said first directing means causing said light from said light source to pass through said first hole and said second directing means causing said light reflected from said contour on said object to pass through said second hole; and

means for producing a second predetermined intensity pattern of light and means for causing a selected one of said first-mentioned and second intensity patterns to be directed onto said contour on said object;

wherein said means for storing data in said contour memory means includes processing means for accepting from said light sensing means a first set of electrical data corresponding to said first-mentioned intensity pattern and a second set of said electrical data corresponding to said second intensity pattern and for calculating a third set of electrical data from said first and second sets of data, said third set of electrical data being said selected set stored in said contour memory means.

19. A method for facilitating the fabrication of a workpiece to be placed onto a light reflective object having a three-dimensional contour thereon to which said workpiece is to be conformed, comprising the steps of:

noncontact topographic scanning of said contour on said object, including the step of directing a predetermined intensity pattern of light onto said contour so that a corresponding intensity pattern of light will be reflected therefrom, the varying intensity pattern of said reflected light being a measure of said three-dimensional contour on said object;

directing said pattern of said reflected light from said object onto a light sensing means;

converting said pattern of light on said light sensing means into a corresponding pattern of electrical data;

selecting a set of said electrical data;

storing said set of said electrical data;

directing a second predetermined intensity pattern of light onto said contour and directing the intensity pattern of light reflected from said object onto said light sensing means;

converting the pattern of light on said light sensing means into a corresponding pattern of electrical data and selecting therefrom a second set of electrical data;

calculating a third set of electrical data from said first-mentioned and second sets of electrical data;

storing said third set of electrical data in place of said first-mentioned set of electrical data;

mounting said workpiece onto a machining means which is responsive to electrical data sequentially presented thereto;

sequentially presenting said stored set of electrical data to said machining means; and

machining said workpiece into a three-dimensional shape in accordance with said stored set of data.

20. An apparatus for faciitating the fabrication of a workpiece to be placed onto a light reflective object having a three-dimensional contour thereon to which said workpiece is to be conformed, comprising:

housing means;

light source means on said housing means and first directing means for directing the light from said light source means toward said contour;

optical plate means on said housing means interposed in the path of said light from said light source means for controlling the magnitude of said light so as to facilitate an illumination of said contour with a predefined intensity pattern, said light being reflected in a corresponding intensity pattern indicative of said three-dimensional contour on said object;

second directing means on said housing means in the path of said reflected light from said contour for directing said reflected light to a desired location within said housing means;

light sensing means located at said desired location for converting said intensity pattern of reflected light into a corresponding pattern of electrical data;

contour memory means, and means for storing a selected set of said electrical data in said contour memory means;

machining means for machining a workpiece in accordance with a set of electrical data sequentially presented thereto;

sequencing means for sequentially presenting said selected set of said electrical data to said machining means to cause a machining of said workpiece to a shape corresponding to said contour to enable the shaped workpiece to be fittingly placed onto said contour;

an aperture member disposed in the path of said light from said light source and having spaced first and second holes therethrough, said first directing means causing said light from said light source to pass through said first hole and said second directing means causing said light reflected from said contour on said object to pass through said second hole, said optical plate means being located between said light source and said aperture member; and

means supporting said optical plate means for movement between first and second positions in a direction generally perpendicular to the direction of travel of light therethrough;

wherein said means for storing data in said contour memory means includes means for selectively effecting movement of said optical plate means to one of said first and second positions; and

wherein said means for storing data in said contour memory means includes processing means for accepting first and second sets of electrical data produced by said light sensing means when said optical plate means is respectively in said first and second positions, and for calculating a third set of electrical data from said first and second sets, said third set of electrical data being said selected data set which is stored in said contour memory means and presented by said sequencing means to said machining means.

21. An apparatus for facilitating the fabrication of a workpiece to be placed onto a light reflective object having a three-dimensional contour thereon to which said workpiece is to be conformed, comprising:

means for noncontact topographic scanning of said contour on said object, including means for directing a first predetermined intensity pattern of light onto said contour so that a corresponding intensity pattern of light will be reflected therefrom, the varying intensity pattern of said reflected light being a measure of said three-dimensional contour on said object;

directing means for directing said pattern of said reflected light from said object onto light sensing means;

conversion means for converting said pattern of light on said light sensing means into a corresponding pattern of electrical data;

selection means for selecting a first set of said electrical data;

means for storing said first set of said electrical data;

means for directing a second predetermined intensity pattern of light onto said contour, said directing means directing the intensity pattern of light reflected from said object onto said light sensing means, said conversion means converting the pattern of light on said light sensing means into a corresponding pattern of electrical data, and said selection means selecting therefrom a second set of electrical data;

means for calculating a third set of electrical data from said first and second sets of electrical data;

means for storing said third set of electrical data;

machining means for machining the workpiece in response to electrical data sequentially presented thereto; and

means for sequentially presenting said stored third set of electrical data to said machining means.