Method, system and mold assembly for use in preparing a dental prosthesis

Claims

What is claimed is:

1. A method for use in preparing a dental prosthesis, comprising the steps of:

providing an electrical signal encoding geometric specifications of a substructure of the prosthesis, said specifications including dimensions and shape of a tooth preparation at a dental site at which the prosthesis is to be affixed and configuration of said substructure;

in response to said electrical signal, providing a first mold component having a surface at least approximately conforming to said tooth preparation and a second mold component to produce, in cooperation with said first mold component, a mold cavity having dimensions and configuration corresponding at least substantially to dimensions and configuration of said substructure;

placing said first mold component and said second mold component in predetermined relative positions to form said mold cavity;

introducing into said mold cavity a quantity of a fluidic solidifiable dental material; and

removing a prosthesis substructure form from said mold cavity upon solidification of the dental material with which said mold cavity is filled.

2. The method defined in claim 1 wherein said step of introducing comprises the step of filling one of said first mold component and said second mold component with said fluidic solidifiable dental material prior to said step of placing, said step of placing comprising the step of at least partially inserting the other of said first mold component and said second mold component into said one of said first mold component and said second mold component.

3. The method defined in claim 1 wherein said fluidic solidifiable dental material comprises a semisolid deformable mass, said step of placing comprising the steps of positioning said first mold component and said second mold component on opposite sides of deformable mass and subsequently moving said first mold component and said second mold component towards one another, said step of introducing comprising the step of shearing off a portion of said deformable mass by said first mold component and said second mold component during said step of moving.

4. The method defined in claim 1 wherein said fluidic solidifiable dental material takes the form of a molded blank, said step of placing comprising the steps of positioning said first mold component, said second mold component and said blank so that said first mold component and said second mold component are disposed on opposite sides of said blank and subsequently moving said first mold component and said second mold component towards one another, said step of introducing comprising the step of seating said blank into said mold cavity during said step of moving.

5. The method defined in claim 4 wherein said blank has a shape substantially conforming to said specifications.

6. The method defined in claim 1 wherein said step of providing includes the step of operating a computer to select said first mold component and said second mold component from a plurality of mold preforms in accordance with said specifications.

7. The method defined in claim 1 wherein said step of introducing is performed subsequently to said step of placing.

8. The method defined in claim 7 wherein said step of introducing includes a step of injecting said fluidic solidifiable dental material into said mold cavity upon formation thereof during said step of placing.

9. The method defined in claim 1 wherein said step of introducing is performed in part during said step of placing.

10. The method defined in claim 9 wherein said step of introducing comprises the steps of pouring said fluidic solidifiable dental material into a mold form including one of said first mold component and said second mold component and subsequently shifting the other of said first mold component and said second mold component relatively towards said one of said first mold component and said second mold component to form said mold cavity filled with said fluidic solidifiable dental material.

11. The method defined in claim 1, further comprising the step of selectively removing material from said first mold component prior to said step of placing.

12. The method defined in claim 11 wherein said step of selectively removing is performed automatically in response to said electrical signal.

13. The method defined in claim 11 wherein said step of selectively removing comprises at least one of electro-eroding and ultrasonically treating the material of said first mold component.

14. The method defined in claim 1, further comprising the step of selectively removing material from said second mold component prior to said step of placing.

15. The method defined in claim 14 wherein said step of selectively removing is performed automatically in response to said electrical signal.

16. The method defined in claim 14 wherein said step of selectively removing comprises at least one of electro-eroding and ultrasonically treating the material of said second mold component.

17. The method defined in claim 1 wherein said steps of placing and introducing are performed automatically.

18. The method defined in claim 17 wherein said steps of placing and introducing comprise the steps of operating a computer to control a robotic device to (a) place said first mold component and said second mold component in relative positions to form said mold cavity and (b) introduce into said mold cavity a quantity of a fluidic solidifiable dental material, said computer selecting said relative positions in accordance with information included in said electrical signal defining said relative positions based on a patient's dentition.

19. The method defined in claim 1 wherein said step of placing comprises the steps of attaching said first mold component and said second mold component to respective mold supports and then positioning said mold supports relative to one another.

20. The method defined in claim 19 wherein one of said mold supports comprises a plate member provided with an array of predetermined positions for receiving said first mold component, the other of said mold supports comprising a plate member provided with an array of positions for receiving said second mold component, said positions being determined in part in accordance with information obtained from a scan of a patient's dentition.

21. The method defined in claim 19 wherein said first mold component and said second mold component are each provided with a pin insertable into apertures in the respective mold support.

22. The method defined in claim 1 wherein said first mold component and said second mold component are provided with a plurality of mounting pins, further comprising the step of machining apertures for receiving said mounting pins in a pair of mold support members.

23. The method defined in claim 1 wherein said step of providing an electrical signal comprises the step of receiving said electrical signal.

24. The method defined in claim 23 wherein said electrical signal is transmitted via a telecommunications linkage.

25. The method defined in claim 23 wherein said electrical signal is communicated via a transported memory element.

26. The method defined in claim 25 wherein said memory element is a floppy disk.

27. The method defined in claim 1 wherein said fluidic solidifiable dental material is a deformable metallic composition.

28. The method defined in claim 1 wherein said fluidic solidifiable dental material is taken from the group including a deformable plastic substance, a glass material, a ceramic material, a composite glass and ceramic material.

29. The method defined in claim 1 wherein said second mold component includes a mold body and an insert.

30. The method defined in claim 29, further comprising the step of selectively removing material from said insert prior to said step of placing.

31. The method defined in claim 30 wherein said step of selectively removing is performed automatically in response to said electrical signal.

32. The method defined in claim 1 wherein said first mold component includes a mold body and an insert.

33. The method defined in claim 32, further comprising the step of selectively removing material from said insert prior to said step of placing.

34. The method defined in claim 33 wherein said step of selectively removing is performed automatically in response to said electrical signal.

35. The method defined in claim 1 wherein said tooth preparation takes a post-like form and wherein said first mold component includes a body with a base and a ring-shaped portion at said base.

36. The method defined in claim 35 wherein said ring-shaped portion is a separate piece attached to said body portion.

37. The method defined in claim 36, further comprising the step of selectively removing material from said ring-shaped portion along an inner surface thereof to form with said body a skirt region of said mold cavity.

38. The method defined in claim 1 wherein the prosthesis takes the form of an overlay.

39. The method defined in claim 38 wherein the prosthesis is a crown.

40. The method defined in claim 38 wherein the prosthesis is a bridge.

41. The method defined in claim 1, further comprising the steps of positioning a plurality of third mold components in a predetermined array determined in accordance with information contained in said electrical signal, positioning a plurality of fourth mold components in a corresponding array determined in accordance with information contained in said electrical signal, said first mold component constituting one of said third mold components, said second mold component constituting one of said fourth mold components.

42. The method defined in claim 41 wherein said steps of positioning comprise the steps of placing said third mold components in said predetermined array on a first mold support and of placing said fourth mold components in said corresponding array on a second mold support.

43. The method defined in claim 41 wherein said step of positioning a plurality of fourth mold components comprises the steps of selecting a mold support provided with a plurality of mold parts in said corresponding array, selecting at least one insert piece, and inserting said insert piece in one of said fourth mold components.

44. The method defined in claim 41, further comprising the step of selectively removing material from at least two of said fourth mold components to form a bridging portion between said two of said fourth mold components upon a filling of a mold cavity formed between said two of said fourth mold components and associated ones of said third mold components.

45. The method defined in claim 1, further comprising the steps of:

separating said second mold portion from said first mold portion and said prosthesis substructure form upon solidification of said fluidic solidifiable dental material and prior to said step of removing;

providing a third mold component having an inner surface substantially conforming to an outer surface of the prosthesis, as specified in said electrical signal;

placing said first mold component with the attached prosthesis substructure form and said third mold component in predetermined relative positions to form an additional mold cavity;

introducing into said mold cavity a quantity of another fluidic solidifiable dental material; and

removing a substantially complete prosthesis form from said mold cavity upon solidification of the other fluidic solidifiable dental material with which said additional mold cavity is filled.

46. A system for use in preparing a dental prosthesis, comprising:

signal production means for producing an electrical signal encoding geometric specifications of a substructure of the prosthesis, said specifications including dimensions and shape of a tooth preparation at a dental site at which the prosthesis is to be affixed and configuration of the substructure;

robot means for placing a first mold component and a second mold component, selected in accordance with said electrical signal, in predetermined relative positions to form a mold cavity, said first mold component corresponding in shape and dimensions to said tooth preparation;

filling means for introducing into said mold cavity a quantity of a fluidic solidifiable dental material; and

computing means operatively connected to said receiver means, said robot means and said filling means for controlling and sequencing the operation thereof in response to said electrical signal.

47. The system defined in claim 46, further comprising material removal means operatively connected to said computing means for selectively removing material, in response to signals from said omputing means, from at least one of said first mold component and said second mold component prior to placement of said second mold component into juxtaposition to said first mold component.

48. The ssytem defined in claim 47 wherein said material removal means includes means for removing material by at least one of electro-erosion and ultrasonic removal.

49. The system defined in claim 46 wherein said signal producing means includes receiver means for receiving said electrical signal and reproducing said signal for use by said computing means.

50. A method for manufacturing a customized dental rosthesis, comprising the steps of:

generating electrically encoded data representing a three-dimensional surface of a tooth to be restored, said step of generating including the steps of (a) tracing a contour of said three-dimensional surfaces with a stylus-type instrument provided with an extension disposed outside of he mouth in which said tooth is located and (b) optically monitoring movements of a predetermined point on said extension;

automatically feeding said data to a first computer;

operating said computer to generate an electrical signal encoding specifications of a substructure of the prosthesis, said specifications including dimensions of a tooth preparation at a dental site at which the prosthesis is to be affixed and configuration of the substructure; and

transmitting said electrical signal to a second computer.

51. The method defined in claim 50 wherein said step of generating includes the step of optically scanning said three-dimensional surface.

52. The method defined in claim 51, further comprising the step of preparing said tooth to form said tooth preparation, said three-dimensional surface being a surface of said tooth preparation, said dimensions being actual dimensions of said tooth preparation.

53. The method defined in claim 51, further comprising the step of operating said first computer to calculate said dimensions, said dimensions being projected dimensions of said tooth preparation.

54. The method defined in claim 53 said step of operating said first computer to calculate includes the step of providing input to said first computer to designate dimensions and location of said tooth preparation.

55. The method defined in claim 54 wherein said step of providing input is implemented with a keyboard,

56. The method defined in claim 54 wherein said step of providing input is implemented with a mouse-type device.

57. The method defined in claim 50 wherein said step of operating said first computer to generate includes the step of computing a varying thickness dimension of said substructure so that a porcelain portion of the prosthesis has a substantially constant thickness throughout.

58. The method defined in claim 50 further comprising the step of operating said second computer to automatically control a robotic device to produce said substructure in response to said electrical signal.

59. The method defined in claim 58, further comprising the steps of controlling said robotic device via said second computer to (a) select a first mold component corresponding in dimensions to said tooth preparation, (b) select a second mold component to produce, in cooperation with said first mold component, a mold cavity having dimensions and configuration corresponding to dimensions and configuration of said substructure, (c) place said first mold component and said second mold component in predetermined relative positions to form said mold cavity and (d) fill said mold cavity with a quantity of a fluidic solidifiable dental material.

60. The method defined in claim 50 wherein said first computer and said second computer are disposed at respective locations remote from one another.

BACKGROUND OF THE INVENTION

This invention relates to method for preparing a dental prosthesis. This invention also relates to an apparatus or system for use in carrying out the method. In addition, this invention relates to a mold assembly for preparing a dental prosthesis. More particularly, this invention relates to a method, an associated apparatus or system and a mold assembly for manufacturing substructures, particularly metal or alloy copings, of prosthetic dental overlays such as crowns, bridges and splints.

In accordance with conventional techniques for providing a dental patient with a prosthetic overlay such as a crown, bridge or splint, a dental practitioner grinds the subject tooth or teeth down to form one or more tooth preparations to which the prosthetic device is to be attached. An impression of the tooth preparation or tooth preparations is taken in an elastic material and the impression is used to produce a model with dies. This in turn has a wax shape built to fit the die, so that a metal casting can be processed via the lost wax technique. The metal casting is then provided with a porcelain layer.

This method of casting for manufacturing prosthetic dental devices is labor intensive and, accordingly, expensive. In addition, the time required to make a dental prosthesis by such labor intensive methods is substantial and thus results in considerable delay in providing patients with crowns, bridges and splints.

The metal castings for the prosthetic devices are generally made by dental laboratories from metals or alloys purchased in the form of small ingots. After applying porcelain cover layers to the metal castings, the laboratories ship the finished prothetic products to the dental practitioners who ordered them.

The manufacture of customized dental prostheses entails substantial efforts and time expenditures by dental laboratories to customize the fit of the castings, resulting in a reduction in value of the precious metal and a using of amounts of precious metals in the process that is lost in castings, grindings. The casting system is subject to so many variables as waxing thicknesses, investment expansions, metal homogenities that there are necessarily inaccuracies and errors in castings results, increased expense in the delivery of what is required and delay in the finalized, correctly fitted prosthetic dental devices. In addition, it is frequently necessary for the dental technicians to hand shape required margins as well as eliminate small bubbles from the metal castings and to grind both internal and external surfaces of the prosthetic appliance in preparation for use and insertion in in the patients, mouths. This grinding away of expensive precious metal or any other metals is time consuming and results in inaccuracies, modifications of fit, amd higher costs for precious metals.

In producing bridges or splints pursuant to traditional methods, the bridges or splints are frequently fabricated by using the excess materials of several prior castings, these prior castings being the excess of the sprued units. This manufacturing technique, as discussed above, is labor intensive and therefore results in high costs. In addition, in cases where there are soldered joints in a prosthetic dental device there is an unequal distribution of stress responsive forces throughout the device, and as a consequence multi-unit cases may be subject to failure due to porosity and/or fatigue at the soldered joints. Moreover, gases are generated in the casting and/or soldering process and such gases remain in the metal and are released and weaken the procelain when that material is baked onto the metal.

Because handheld grinding and/or drilling of the metal castings naturally results in reduced accuracies in the shapes of the final products and because conventional techniques for manufacturing dental prostheses such as crowns, bridges and splints are subject to continuous variables from the impression stage, to the modeling, waxing, casting and handheld grinding, a goodly number of dental prostheses are frequently ill-fitting or require multiple corrective steps, which gives rise to further variables, delays and cost increases.

New methodologies based on CAD/CAM and CAE design have recently been introduced. These new methodologies represent the only significant advance in the dental arts for centuries. Pursuant to the new techniques, a dental prosthesis such as a bridge is machined or milled from a solid chunk of material under computer control. The milling is of both internal and external surfaces of adjacent dental substructures and proceeds generally from tooth position to tooth position. Upon reaching the final tooth position in a bridge array, numerous inaccuracies have arisen from the extensive milling or grinding.

OBJECTS OF THE INVENTION

An object of the present invention is to provide an improved method for producing dental prostheses.

Another object of the present invention is to provide such a method which is more ecomomical and efficient than conventional techniques.

Another, more particular, object of the present invention is to provide such a method which reduces the labor required.

Another particular object of the present invention is to provide such a method which reduces or substantially eliminates waste of precious metals.

A further particular object of the present invention is to provide such a method wherein several dental prostheses may be produced substantially simultaneously.

Yet another object of the present invention is to provide such a method which reduces the costs of producing prosthetic dental appliances.

An additional particular object of the present invention is to provide such a method which produces improved dental prosthesis and, more particularly, dental prostheses which are stronger, of a closer and more accurate fit, more durable and less prone to failure than conventional prosthetic dental devices.

Yet another object of the present invention is to provide a system for essentially automatically preparing prosthetic dental implants, restorations, splints, fixed bridges, crowns or inlays/overlays.

A further object of the present invention is to provide a mold assembly useful in producing prosthetic dental appliances.

SUMMARY OF THE INVENTION

A method for use in preparing a dental prosthesis comprises, in accordance with the present invention, the step of receiving an electrical signal encoding geometric specifications of a substructure of the prosthesis, the specifications including dimensions and shape of a tooth preparation at a dental site at which the prosthesis is to be affixed and the configuration of the substructure. In a subsequent step performed in response to the electrical signal, a computer is operated to automatically select a first mold component having a surface corresponding in dimensions to the tooth preparation and to automatically select a second mold component to produce, in cooperation with the first mold component, a mold cavity having dimensions and configuration corresponding to dimensions and configuration of the substructure. The first mold component and the second mold component are placed in predetermined relative positions to form the mold cavity and the mold cavity is filled with a quantity of a fluidic solidifiable dental material, i.e., a precious metal, a semiprecious alloy, a plastic composite, a porcelain glass material or any other usable dental restorative material.

Pursuant to another feature of the present invention, a metal form is removed from the mold cavity upon solidification of the fluidic solidifiable dental material with which the mold cavity is filled. The fluidic solidifiable dental material may take the form of liquid metal or a semi-solid metallic composition.

The filling step preferably comprises the step of introducing the fluidic solidifiable dental material into one of the mold components prior to the step of placing the mold components into juxtaposition with one another. In that event, the step of placing comprises the step of at least partially inserting the one mold component into the other mold component.

When the fluidic solidifiable dental material comprises a semisolid deformable mass, the step of placing comprises the steps of positioning the mold components on opposite sides of deformable mass and subsequently moving the mold components towards one another. The fluidic solidifiable dental material is thereby introduced into the mold cavity is sheared off of the deformable mass by the mold components during the movement of the mold components towards one another.

In accordance with an alternative embodiment of the present invention, the step of filling is performed subsequently to the placement of the first mold component and the second mold component in juxtaposition to one another to form the mold cavity. In that case, the step of filling comprises the step of injecting the fluidic solidifiable dental material (generally in a liquid form) into the mold