Dental post system

A dental post system for use in the formation and retention of a dental restoration on a tooth stub. The system includes a dental post having an elongated cylindrical pin with a lower anchoring portion which is secured into a prepared bore in the tooth stub, and an upper end portion which projects from the tooth stub and is secured in a metallic core upon which the restoration is fabricated. An interlock arrangement coacts with the upper end portion to provide permanent securement of the metallic core on the cylindrical pin. The interlock arrangement prevents axial lift off of the metallic core from the dental post as well as preventing rotational displacement between the metallic core and the dental post. A core pattern is used to form the metallic core, where the core pattern can be fabricated from a preformed plastic core or can be built up directly onto the upper end portion when the dental post is disposed in the bore of the tooth stub.

What is claimed is:

1. A dental post system for use in preparing a dental restoration, comprising:

a dental core;

an elongated cylindrical post having a lower anchoring portion for secured retention within a cement prepared bore in a tooth stub, and an upper end portion for projecting from the tooth stub to be received within an aperture in said dental core, the restoration being disposed on said dental core;

interlock means for securing said dental core onto said upper end portion of said cylindrical post to prevent both axial lift-off as well as rotational displacement between said dental core and said cylindrical post; and

a laterally extending shoulder portion being provided on said cylindrical post between said lower anchoring portion and said upper end portion to define stop means for engaging said dental core to prevent insertion of said lower anchoring portion into said aperture of said dental core so that said dentral core is positioned on said upper end portion at a predetermined location to permit coaction between said interlock means and said upper end portion.

2. A dental post system as in claim 1, wherein said interlock means includes a substantially U-shaped clip member having a pair of opposing legs and a bight portion; and

a pair of grooves provided in opposing sides of said upper end portion of said post for receiving said legs of said clip member therein as said clip member transversely straddles said upper end portion, thereby locking said dental core onto said upper end portion, whereby a portion of said clip member is disposed in said dental core.

3. A dental post system as in claim 2, wherein said clip member is a continuous wire bent into a U-shape.

4. A dental post as in claim 3, wherein said wire has a circular cross section.

5. A dental post as in claim 3, wherein said wire has a semi-circular cross section.

6. A dental post as in claim 5, wherein outer surfaces of said wire are substantially flat.

7. A dental post system as in claim 2, wherein one leg of said clip member is shorter than the other leg to facilitate insertion into said grooves.

8. A dental post system as in claim 2, wherein distal ends of said legs are tapered.

9. A dental post system as in claim 2, wherein each of said legs of said clip member has a transverse cross section larger than transverse depth of each associated one of said grooves of said post so that said legs transversely project outwardly from said grooves, respectively.

10. A dental post system as in claim 2, wherein each of said legs of said clip member has a length greater than the diameter of said post so as to transversely extend beyond said upper end portion of said post.

11. A dental post system as in claim 1, wherein said lower anchoring portion includes a plurality of externally spaced apart helical flutes longitudinally disposed about the longitudinal axis of said post for retaining said lower anchoring portion within the cement prepared bore and also for providing a vent for said post when being inserted into the cement prepared bore.

12. A dental post system as in claim 1, wherein at least a major portion of said upper end portion of said post has a smooth cylindrical periphery.

13. A dental post system as in claim 1, wherein said interlock means includes an elongated cross pin, and an aperture transversely extending into said upper end portion of said post for receiving a portion of said cross pin therein, thereby locking said dental core onto said upper end portion, whereby another portion of said cross pin is disposed in said dental core.

14. A dental post system as in claim 13, wherein said cross pin includes an elongated threaded body portion, a removable flattened tang on one end of said threaded body portion, and a rod on an opposite end of said threaded body portion, said aperture extending entirely through said upper end portion and receiving at least a part of said rod, said threaded body portion being disposed in a mating internally threaded bore provided in said dental core.

15. A dental post system as in claim 13, wherein said cross pin includes a smooth cylindrical rod, and said aperture in said upper end portion includes a detent for receiving a forward end of said rod.

16. A dental post system as in claim 15, wherein said upper end portion is externally threaded for engaging a mating internally threaded bore defining said aperture provided in said dental core.

17. A dental post system as in claim 15, wherein said upper end portion has a smooth cylindrical periphery for being received within a blind bore defining said aperture provided in said dental core.

18. A dental post system as in claim 15, wherein said upper end portion is externally threaded for engaging in an internally threaded nut to secured said upper end portion in said aperture provided in said dental core.

19. A dental post system as in claim 1, wherein said interlock means includes said upper end portion being externally threaded with a flat surface across a portion of said threaded upper end portion, and said aperture provided in said dental core having a flat wall matingly engaging said flat surface, and an internally threaded nut threaded onto said threaded upper end portion to secure said upper end portion in said aperture.

20. A dental post system as in claim 1, and further comprising a pre-formed plastic core including an embedded mating pattern for engaging with said interlock means, said plastic core being mounted onto the tooth stub to obtain a core pattern for casting said dental core.

21. A dental post system as in claim 20, wherein a central bore is provided in said pre-formed plastic core for receiving therein said upper end portion of said post.

22. A dental post system as in claim 20, wherein said pre-formed plastic core is of frustoconical shape.

23. A dental post system as in claim 20, and including recess means provided in a bottom surface of said pre-formed plastic core to receive wax therein to improve the contour shape of said plastic core.

24. A dental post system as in claim 21, wherein a pair of transverse channels are provided through said pre-formed plastic core, said channels straddling and partially intersecting said control bore for receiving opposing legs of a substantially U-shaped clip member inserted therein for locking said plastic core to said cylindrical post, and a recess provided in one wall of said pre-formed plastic core at the mouths of said channels for receiving a bight portion of said clip member.

25. A dental post system as in claim 21, wherein a transverse channel is provided in said pre-formed plastic core, said channel intersecting said central bore for receiving a cross pin inserted therethrough for locking said plastic core to said cylindrical post.

26. A dental post system as in claim 25, wherein said transverse channel extends entirely through said plastic core, a channel portion on one side of said central bore being internally threaded and larger than a channel portion on the other side of said central bore.

27. A dental post system as in claim 21, wherein said central bore extends entirely through said preformed plastic core and is internally threaded.

28. A dental post system as in claim 21, wherein said central bore in smooth and extends only partially upward from a bottom portion of said pre-formed plastic core.

29. A dental post system for use in preparing a dental restoration, comprising:

a dental core;

an elongated cylindrical post having a lower anchoring portion for secured retention within a cement prepared bore in a tooth stub, and an upper end portion for projecting from the tooth stub to be received within an aoerture in said dental core, the restoration being disposed on said dental core;

interlock means for securing said dental core onto said upper end portion of said cylindrical post to prevent both axial lift-off as well as rotational displacement between said dental core and said cylindrical post;

a neck portion being provided around said cylindrical post between said lower anchoring portion and said upper end portion;

said upper end portion being tapered outward from said neck portion upwardly to a top end of said cylindrical post so that said top end is wider than said neck portion to define one part of said interlock means which prevents the axial lift-off of said dental core, said dental core aperture being matingly tapered; and

a radially projecting key longitudinally extending along said tapered upper end portion for being received in a mating keyway provided in said dental core in communication with said dental core aperture to define another part of said interlock means which prevents the rotational displacement of said dental core.

30. A dental post system as in claim 29, wherein said lowering anchoring portion includes a plurality of externally spaced apart helical flutes longitudinally disposed about the longitudinal axis of said post for retaining said lower anchoring portion within the cement prepared bore and also for providing a vent for said post when being inserted into the cement prepared bore.

31. A dental post system as in claim 29, and further comprising a pre-formed plastic core including an embedded mating pattern for engaging with said interlock means, said plastic core being mounted onto the tooth stub to obtain a core pattern for casting said dental core, a central bore being provided in said pre-formed plastic core, said central bore being matingly tapered to receive said tapered upper end portion of said post, and a mating keyway provided in said pre-formed plastic core in communication with said central bore to receive said radially projecting key disposed on said tapered upper end portion of said post.

32. A method of restoring devitalized dentition, comprising the steps of:

preparing a tooth stub for receiving a dental post whose lower portion is to be permanently cemented into the tooth stub with its upper end portion projecting upwardly from the tooth stub;

disposing interlock means on the upper end portion for the permanent securement of a metallic core onto the dental post;

forming a core pattern on the tooth stub with the upper end portion and the interlock means disposed in the core pattern, and with the upper end portion and interlock means having mating portions within the core pattern;

releasing the interlock means and removing the core pattern from the upper end portion;

casting a metallic core from the core pattern;

interlocking the metallic core onto the upper end portion of the dental post using said interlock means so that the metallic core is secured on the tooth stub; and

fabricating a restoration upon the metallic core after the metallic core is secured on the tooth stub.

33. A method as in claim 32, and further comprising the step of cementing the lower portion of the dental post into the tooth stub prior to forming the core pattern.

34. A method as in claim 32, wherein said step of forming the core pattern comprises:

interlocking a pre-formed plastic core onto the upper end portion of the dental post using said interlock means; and

contouring the pre-formed plastic core as needed to form the desired core pattern.

35. A method as in claim 34, wherein said step of forming the core pattern further comprises the placing of a wax material between said plastic core and the tooth stub.

36. A method as in claim 32, wherein the interlock means includes a substantially U-shaped clip; and comprising:

placing the U-shaped clip to straddle the upper end portion of the dental post with the thickness of the legs of the clip being partially received in a pair of grooves provided in opposing sides of the upper end portion and the rest of the thickness of the legs being received within the formed core pattern;

removing the clip to remove the formed core pattern from the tooth stub;

seating the cast metallic core onto the upper end portion;

reinserting the clip back into composite grooves defined between the groove portions cast into the metallic core and the groove portions in the upper end portion so as to lock the metallic core to the dental post for securement on the tooth stub; and

cutting off any free end portions of the legs of the clip extending beyond the periphery of the metallic core.

37. A method as in claim 32, wherein the interlock means includes an elongated cross pin; and comprising:

placing the elongated cross pin into an aperture formed in the upper end portion with a portion of the cross pin being received within the formed core pattern;

removing the cross pin to remove the formed core pattern from the tooth stub;

seating the cast metallic core onto the upper end portion; and

reinserting the cross pin back into a coaxial aperture defined between an aperture cast into the metallic core and the aperture in the upper end portion so as to lock the metallic core to the dental post for securement on the tooth stub.

38. A method as in claim 37, wherein the cross pin is inserted entirely through the metallic core.

39. A method as in claim 37, wherein the cross pin is inserted through one side of the metallic core and partially into the upper end portion.

40. A method as in claim 32, wherein said step of forming the core pattern includes using impression material to build up the core pattern directly onto the upper end portion when the dental post is disposed in the tooth stub.

41. A method as in claim 32, including providing the dental post with a laterally extending shoulder portion between the upper end portion and lower portion, and providing the metallic core with a mating shoulder portion for preventing the insertion of the lower end portion into the metallic core.

42. A method as in claim 32, wherein said preparing step comprises drilling into the tooth stub to form an elongated bore; and including the steps of introducing a cement into the bore, and securing the lower portion of the dental post into the bore.