Retrievable dental prothesis apparatus and method of fabrication

• US 5,180,303 A
• Filed: 08/15/1991
• Issued: 01/19/1993
• Est. Priority Date: 09/21/1988
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Hornburg, Wynn E., Beumer, John III
• Primary Examiner(s): WEHNER, CARY ELLEN
• Application Number:
  US07/749,494
• Time in Patent Office: 523 Days
• Field of Search: 433/167, 433/169, 433/172, 433/173, 433/174, 433/175, 433/176, 433/206, 433/214, 433/213, 433/165, 433/166, 249/54, 264/19, 408/72 B, 408/85, 29/160.6, 164/34, 164/35, 164/DIG. 4
• US Class Current: 433/173
• CPC Class Codes: A61C 13/0003 Making bridge-work, inlays, implants or the like
• CPC Class Codes: A61C 8/0048 Connecting the upper structure to the implant, e.g. bridging bars A61C8/0028 takes precedence

Abstract

A retrievable dental prothesis fabricated by using a special plastic cylinder using low-wax casting procedures for the purpose of eliminating the need for a visible titanium abutment cylinder typically used for conventional prostheses. This improves the appearance and functional features of the prosthesis. The prosthesis is connected by a titanium alloy screw directly to an implant embedded in a patient'"'"'s underlying dental bone structure. Internal hexagonal surfaces formed at the base of the prosthesis which mate with hexagonal surfaces of an upward extension of the implant prevent loosening or rotation of the prosthesis due to rotational forces and vibrations and enable fabrication of single implant-supported restoration. However, the prosthesis may be used without such internal hexagonal surfaces if desired. Because an abutment cylinder is not used, the prosthesis provides increased working space between the implant and corresponding opposite upper or lower existing teeth. An access aperture may be provided at the back of the prosthesis for allowing access by an installation tool to the titanium alloy screw. The prosthesis is formed by shaping a wax pattern around the plastic cylinder to represent a patient'"'"'s tooth to be replaced by the prosthesis. The prosthesis is then cast out of gold-palladium alloy. A bottom surface at the base of the prosthesis is polished using a lapping tool and guide pin. Cutting edges may be used on the lapping tool to facilitate deburring of the bottom surface.

Claims

1. A retrievable dental prosthesis adapted to be removably connected by a screw to an implant anchor, said implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, said dental prosthesis comprising an integral cast metal portion removably connected to said implant anchor, said cast metal portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said cast metal portion having a base with an annular bottom surface and means at said base for engaging said implant and interlocking therewith in order to prevent rotation of said cast metal portion with respect to said implant anchor, said cast metal portion having an access aperture passing therethrough from an upper position above said base downward toward said base, said screw being disposed inside and at a bottom of said aperture in order to removably connect said cast metal portion to said implant anchor so that said top surface of said patient'"'"'s overlying gingiva and directly interfaces with said implant anchor, and so that said base interlocks with said implant anchor below said top surface of said gingiva, said aperture providing access to said screw so that said screw is capable of being selectively (a) loosened in order to remove said cast metal portion from said implant, and (b) tightened in order to removably connect said cast metal portion to said implant anchor.

2. The retrievable dental prosthesis of claim 1 wherein said engaging means includes internal mating surfaces in a recess in said base capable of engaging and interlocking with corresponding mating surfaces at an upward extension of said implant.

3. The retrievable dental prosthesis of claim 2 wherein said internal mating surfaces and said corresponding mating surfaces are hexagonal surfaces.

4. The retrievable dental prosthesis of claim 1 wherein said cast metal portion is contoured near said base to facilitate corresponding soft tissue health adjacent said base and to provide access for oral hygiene purposes.

5. The retrievable dental prosthesis of claim 1 wherein said cast metal portion is a dental alloy.

6. The retrievable dental prosthesis of claim 5 wherein said dental alloy is gold-palladium alloy.

7. The retrievable dental prosthesis of claim 5 wherein said dental alloy is 52% gold-palladium alloy.

8. A retrievable dental prosthesis adapted to be removably connected by a screw to an implant anchor, said implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, said dental prosthesis comprising an integral cast metal portion removably connected to said implant anchor, said cast metal portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said cast metal portion having a base and means at said base for engaging said implant anchor and interlocking therewith in order to prevent rotation of said cast metal portion with respect to said implant anchor, said cast metal portion having an access aperture passing therethrough from an upper position above said base downward toward said base, said screw being disposed inside and at a bottom of said aperture in order to removably connect said cast metal portion to said implant anchor so that said base extends downward below said top surface of said patient'"'"'s overlying gingiva and is directly connected to and interlocked with said implant anchor below said top surface of said gingiva, said aperture providing access to said screw so that said screw is capable of being selectively (a) loosened in order to remove said cast metal portion from said implant, and (b) tightened in order to removably connect said cast metal portion to said implant anchor, said cast metal portion having an annular collar at said base, said collar having an annular ledge at the top thereof.

9. The retrievable dental prosthesis of claim 8 wherein said cast metal portion has a layer of porcelain fused to the outside surface thereof, said layer of porcelain extending downward to said ledge.

10. The retrievable dental prosthesis of claim 8 wherein said cast metal portion has a layer of resin at the outside surface thereof, said layer of resin extending downward to said ledge.

11. A retrievable dental prosthesis adapted to be removably connected to an implant anchor, said implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, said dental prosthesis comprising a screw and an integral cast metal portion removably connected to said implant anchor by said screw, said cast metal portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said case metal portion having a base with an annular bottom surface and means at said base for engaging said implant anchor and interlocking therewith in order to prevent rotation of said cast metal portion with respect to said implant anchor, said cast metal portion having an access aperture passing therethrough from an upper position above said base downward toward said base, said screw being disposed inside and at a bottom of said aperture in order to removably connect said cast metal portion to said implant anchor so that said annular bottom surface of said base extends downward below said top surface of said patient'"'"'s overlying gingiva and directly interfaces with said implant anchor, and so that said base interlocks with said implant anchor below said top surface of said gingiva, said aperture providing access to said screw so that said screw is capable of being selectively (a) loosened in order to remove said cast metal portion from said implant, and (b) tightened in order to removably connect said cast metal portion to said implant anchor.

12. The retrievable dental prosthesis of claim 11 wherein said access aperture has a frustro-conically-shaped surface at said bottom thereof which engages a corresponding frustro-conically-shaped surface at the bottom of a head of said screw, said head having a recess therein with internal surfaces.

13. The retrievable dental prosthesis of claim 12 wherein said access aperture enters said cast metal portion so that said aperture provides access allowing an installation tool to engage said internal surfaces of said recess in said head in order to selectively loosen and to selectively tighten said screw.

14. The retrievable dental prosthesis of claim 11 wherein said access aperture has a flat annular-shaped surface at said bottom thereof which engages a corresponding flat annular-shaped surface at the bottom of a head of said screw, said head having a slot therein.

15. A retrievable dental prosthesis adapted to be removably connected to an implant anchor, said implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, said dental prosthesis comprising a screw and an integral cast metal portion removably connected to said implant anchor by said screw, said cast metal portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said cast metal portion having a base and means at said base for engaging said implant anchor and interlocking therewith in order to prevent rotation of said base metal portion with respect to said implant anchor, said cast metal portion having an access aperture passing therethrough from an upper position above said base downward toward said base, said screw being disposed inside and at a bottom of said aperture in order to removably connect said cast metal portion to said implant anchor so that said base extends downward below said top surface of said patient'"'"'s overlying gingiva and is directly connected to and interlocked with said implant anchor below said top surface of said gingiva, said aperture providing access to said screw so that said screw is capable of being selectively (a) loosened in order to remove said cast metal portion from said implant, and (b) tightened in order to removably connect said cast metal portion to said implant anchor, said access aperture having a frusto-conically-shaped surface at said bottom thereof which engages a corresponding frusto-conically-shaped surface at the bottom of a head of said screw, said head having a recess therein with internal surfaces, said access aperture entering said cast metal portion from a back of said portion so that said aperture provides access allowing an installation tool to engage said internal surfaces of said screw in said head in order to selectively loosen and to selectively tighten said screw.

16. A retrievable dental prosthesis adapted to be removably connected to an implant anchor, said implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, said dental prosthesis comprising a screw and an integral cast metal portion removably connected to said implant anchor by said screw, said cast metal portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said cast metal portion having a base with an annular bottom surface, said cast metal portion having an access aperture passing therethrough from an upper position above said base downward toward said base, and a screw disposed inside and at a bottom of said aperture removably connecting said cast metal portion to said implant anchor so that said annular bottom surface of said base extends downward below said top surface of said patient'"'"'s overlying gingiva and directly interfaces with said implant anchor below to said screw so that said screw is capable of being selectively (a) loosened in order to remove said cast metal portion from said implant, and (b) tightened in order to removably connected said cast metal portion to said implant.

17. A combination retrievable dental prosthesis and implant anchor comprising an implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, an integral cast metal portion removably connected to said implant anchor, said cast metal portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said cast metal portion having a base, an access aperture passing therethrough from an upper position above said base downward toward said base, and a connector disposed inside and at a bottom of said aperture removably connecting said cast metal portion to said implant anchor so that said base extends downward below said top surface of said patient'"'"'s overlying gingiva and directly interfaces with said implant anchor below said top surface of said gingiva, said aperture providing access to said connector so that said connector is capable of being selectively (a) loosened in order to remove said cast metal portion form said implant, and (b) tightened in order to removably connect said cast metal portion to said implant.

18. A cylinder apparatus used for fabricating a cast metal dental prosthesis comprising an elongated cylindrically-shaped member having a first bore passing longitudinally therethrough, said first bore having a frustro-conically-shaped surface at the bottom thereof, said member having a cylindrically-shaped recess at a bottom thereof and a second bore therein having a smaller diameter than said first bore connecting said first bore to said recess, said member having an annular collar at said bottom thereof and a portion extending downward from said collar, said collar having an annular ledge at a top thereof, said member being made out of a material capable of being used for lost-wax casting procedures.

19. The cylinder of claim 18 wherein said material is a plastic material.

20. Milling apparatus used for deburring a cast metal dental prosthesis comprising:

a lapping tool having a shank with a deburring flange attached thereto, a shaft connected to said flange and an engaging rod connected to said shank, said shank capable of rotatably engaging a recess in a base of said cast metal prosthesis so that said deburring flange engages a bottom surface at said base of said prosthesis; and

a generally cylindrically-shaped elongated guide pin having an internal bore passing longitudinally therethrough, said guide pin capable of engaging an internal bore in said cast metal prosthesis so that one end of said guide pin engages a bottom of said bore in said prosthesis while said engaging rod of said lapping tool rotatably engages said internal bore in said guide pin in order that said deburring flange is capable of rotating and polishing said bottom surface of said prosthesis.

21. The milling apparatus of claim 20 wherein said deburring flange has cutting edges thereon.

22. The milling apparatus of claim 20 wherein said guide pin has a frustro-conically-shaped surface at said one end.

23. The milling apparatus of claim 20 wherein said one end of said guide pin is a flat end.

24. A method of fabricating a cast metal dental prosthesis comprising the steps of:

placing an implant in a master cast so that external surfaces of an upward extension of said implant are properly oriented to match orientation of said surfaces when said implant is placed in a patient'"'"'s dental bone structure;

placing a plastic cylinder on top of said implant;

shaping a wax pattern over said plastic cylinder to generally represent contours of a tooth to be replaced by said prosthesis;

removing said cylinder with said wax pattern from said implant; and

casting a cast metal prosthesis using said cylinder with said wax pattern and lost-wax casting procedures.

25. The method of claim 24 further comprising the step of shaping wax in a recess in a bottom of said plastic cylinder before shaping said wax pattern in order to form internal surfaces that are capable of mating with said external surfaces of said implant.

26. The method of claim 24 further comprising the step of polishing a bottom surface of said cast metal prosthesis.

27. The method of claim 24 further comprising the step of fusing a porcelain layer to an outside surface of said cast metal prosthesis.

28. The method of claim 24 further comprising the step of applying a resin layer to an outside surface of said cast metal prosthesis.

29. The method of claim 24 wherein said cast metal prosthesis is made out of gold-palladium alloy.

30. The method of claim 24 further comprising the step of cutting a top portion off said plastic cylinder before shaping said wax pattern so that said cylinder is sized to represent the height of said tooth to be replaced.

31. The method of claim 24 wherein said cast metal prosthesis has an annular collar at the base metal prosthesis has an annular collar at the base thereof.

32. The method of claim 24 wherein said plastic cylinder has internal surfaces formed integrally in a recess in a bottom of said plastic cylinder, said internal surfaces capable of mating with said external surfaces of said implant.

33. A combination retrievable dental prosthesis and implant anchor comprising an implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, an integral cast metal portion removably connected to said implant anchor, said cast metal portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said cast metal portion having a base with an annular bottom surface and means at said base for engaging said implant anchor and interlocking therewith in order to prevent rotation of said base metal portion with respect to said implant anchor, said cast metal portion having an access aperture passing therethrough from an upper position above said base downward toward said base, and a screw disposed inside and at a bottom of said aperture removably connecting said cast metal portion to said implant anchor so that said annular bottom surface of said base extends downward below said top surface of said patient'"'"'s overlying gingiva and directly interfaces with said implant anchor below said top surface of said gingiva, said aperture providing access to said screw so that said screw is capable of being selectively (a) loosened in order to remove said cast metal portion from said implant, and (b) tightened in order to removably connect said cast metal portion to said implant anchor.

34. A method of installing a dental prosthesis in a patient'"'"'s jawbone, said jawbone having a predrilled bore therein, said dental prosthesis having an aperture therein and a base, said method comprising the steps of:

installing an implant anchor in said predrilled bore formed in said jawbone below a top surface of said patient'"'"'s overlying gingiva;

mounting a dental prosthesis directly on top of said implant anchor so that said base of said prosthesis extends downward below said top surface of said patient'"'"'s overlying gingiva and directly interfaces with said implant anchor below said top surface of said gingiva, said dental prosthesis comprising an integral cast metal portion shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis; and

removably connecting said dental prosthesis to said implant anchor with a screw placed into said aperture in said dental prosthesis and threaded into said implant anchor.

35. The method of claim 34 wherein said mounting step includes engaging and interlocking said base of said dental prosthesis to said implant anchor so that said dental prosthesis is prevented from rotating with respect to said implant anchor.

36. The method of claim 35 wherein said base of said dental prosthesis has an annular bottom surface and said implant anchor has an annular top surface, said annular top and bottom surfaces directly interfacing with each other after said dental prosthesis is mounted onto said implant anchor.

37. A retrievable dental prosthesis adapted to be removably connected by a connector to an implant anchor, said implant anchor adapted to be embedded in a patient'"'"'s dental bone structure and to be disposed below a top surface of said patient'"'"'s overlying gingiva, said dental prosthesis comprising an integral portion removably connected to said implant anchor, said integral portion being shaped to generally represent contours of a tooth of said patient to be replaced by said prosthesis, said integral portion having a base and an access aperture passing therethrough from an upper position above said base downward toward said base, said connector being disposed inside said aperture removably connecting said integral portion to said implant anchor so that said base extends downward below said top surface of said patient'"'"'s overlying gingiva and directly interfaces with said implant anchor below said top surface of said gingiva, said aperture providing access to said connector so that said connector is capable of being selectively (a) loosened in order to remove said integral portion from said implant, and (b) tightened in order to removably connect said integral portion to said implant.