MANUFACTURE OF A DENTAL PROSTHESIS

Abstract

A method of manufacture of a dental prosthesis is described, comprising using a rotary milling or drilling tool (16) to mill or drill a block (12) of a sintered ceramic material. The use of a tool (16) to mill or drill material from a block (12) of a sintered ceramic material such as lithium silicate or lithium disilicate allows manufacture of a glass ceramic dental prosthesis in a relatively efficient manner.

Claims

1. A method of manufacture of a dental prosthesis comprising using one of a rotary milling and a drilling tool to mill or drill a block of a sintered ceramic material.

2. The method according to claim 1, wherein the sintered ceramic material is a sintered glass ceramic material.

3. The method according to claim 2, wherein the sintered glass ceramic material comprises one of lithium disilicate and lithium silicate.

4. The method according to claim 1 wherein the tool is a milling tool of ball-nosed, form.

5. The method according to claim 1 wherein the tool is a drilling tool.

6. The method according to claim 1 wherein the tool is provided with a hard coating.

7. The method according to claim 6, wherein a diamond coating is applied to the outer surface of at least the end part of the tool.

8. The method according to claim 1 wherein the tool incorporates at least one of PCD element, PCBN elements and CBN elements.

9. A dental prosthesis manufactured using the method of claim 1.

10. A milling or drilling tool adapted for use in the method of claim 1.

11. A method according to claim 1, wherein the tool is a milling tool of bull-nosed form.

12. A method according to claim 1, wherein the tool is a milling tool of flat ended form.

Description

[0014] The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

[0015] FIG. 1 is a diagrammatic view illustrating the manufacture of a dental prosthesis in accordance with an embodiment of the invention; and

[0016] FIG. 2 is a view illustrating the milling tool used in the manufacturing method of FIG. 1.

[0017] Referring to the accompanying drawings, a method of manufacture of a dental prosthesis 10 comprises the steps of supporting a block 12 of a sintered ceramic material, for example a glass ceramic material for milling or drilling. By way of example, the sintered glass ceramic material block may be of lithium silicate or lithium disilicate. Materials that may be used include IPS e.max CAD (RTM) from Ivoclar, Celtra Duo (RTM) from Dentsply or VITA SUPRINITY (RTM) from Vita. The block 12 of sintered glass ceramic material is support within a machining apparatus 14 such as a five axis machining apparatus. The machining apparatus 14 includes a rotary milling tool 16 that is supported in such a manner as to allow the tool 16 to be rotated at high speed about its axis. The block 12 is supported by a support arrangement 18. The machine 14 is controlled in such a manner that the tool 16 can be moved in at least three perpendicular directions relative to the block 12 in a controlled fashion. By way of example, it may comprise a 3-axis machine, but it could comprise, for example, a 5- or 6-axis machine. Furthermore, the manner in which the block 12 is supported is such that controlled tilting of the block 12 relative to the tool 16 is permitted.

[0018] As shown in FIG. 2, the tool comprises a shank 20 adapted to be fitted to a chuck forming part of the apparatus 12. From the shank 20 extends a fluted shaft 22. The free end of the fluted shaft 22 is, in this example, of ball-nosed form and serves to define a cutting face 24 which, upon engagement with the block 12, can serve to cut or mill material from the block 12. As sintered ceramic materials are typically of high hardness, the tool 16 is conveniently of tungsten carbide or silicon carbide or another suitable hard material such as cermet, and it may have a diamond material coating applied thereto to enhance the ability of the tool to cut or mill ceramic materials. The diamond coating may be applied to the entire tool 16, or just to the parts thereof that, in use, engage and cut or mill the block 12. The tool 16 could be brazed with a hard material such as PCD, PCBN or CBN or could be of dual material form, for example of sintered form from a material incorporating PCD, PCBN and/or CBN and carbide so that PCD, PCBN and/or CBN material elements are encapsulated within the carbide material.

[0019] It will be appreciated that with the block 12 supported in the manner outlined hereinbefore, and with the tool 16 driven for rotation, the tool 16 and/or the block 12 can be moved such that a part of the tool 16 moves into engagement with the block 12. The engagement between the block 12 and the cutting face 24 of the tool 16 results in the tool 16 serving to cut or mill material from the block 12. By moving and/or tilting the tool 16 and/or the block 12, it will be appreciated that over time the block 12 can be formed to substantially the desired shape.

[0020] After milling of the block 12 to approximately the desired shape, the tool 16 may be replaced with a tool 16a of substantially the same form as the originally used tool 16, but of smaller diameter and with a ball nosed end part of a smaller radius of curvature. By repeating the above described milling process using the smaller diameter tool 16a, it will be appreciated that a finishing process may be performed, finishing the prosthesis 10 to a desired shaped.

[0021] It will be appreciated that through the use of a milling tool to cut material from the block by milling or drilling, rather than a rotary grinding tool to grind material therefrom, a prosthesis can be manufactured without suffering from the disadvantages associated with the use of grinding tools as outlined hereinbefore. The invention thus uses milling or drilling, as opposed to grinding, in the shaping of a block of a sintered ceramic material, such a technique being quicker than grinding.

[0022] Whilst in the description hereinbefore, reference is made to using a second tool of smaller dimensions in undertaking a finishing operation, it will be appreciated that this represents merely one example, and that this may not always be required. By way of example, the entire process may be undertaken using a single tool.

[0023] Although the description hereinbefore is of the use of a milling tool of ball-nosed form, the invention is not restricted in this regard and tools of other shapes and forms may be used. By way of example, where the tool is a rotary milling tool, it could be of flat ended or bull-nosed form, if desired. Alternatively, the tool could comprise a rotary drilling tool, for example of pointed form.

[0024] Whilst a specific embodiment of the invention is described hereinbefore, it will be appreciated that a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.