CA2456001A1 - Orbital dental polishing device - Google Patents

Abstract

Currently dental laboratories use a lathe for the polishing of the dental crown. Such lathes use a polishing disc brush mounted on a rotating shaft and which generally cannot polish the deeper parts of the surface of the appliance without wearing down the surrounding anatomy. The present device provides a brush which uses an orbital motion to thereby better preserve the anatomy of the crown.

Description

ORBITAL DENTAL POLISHING DEVICE
Cross-Reference to Related Applications This application is a continuation-in-part of United States patent application no. 09/920,046 filed 1 August 2001.
Technical Field [0001] The invention relates to the field of tools for polishing crowns, bridges, dental appliances such as dentures and the like, or jewellery, and more particularly a device which polishes crowns, bridges, dental appliances such as dentures and the like, or jewellery, using an orbital motion.
Background [0002] Currently dental laboratories prepare crowns, bridges and dental appliances such as dentures. After a crown is cast out of gold alloy or porcelain, it is necessary to polish the upper surface of the crown. The upper or functional surface of the crown, like a natural tooth, has a complex convoluted shape or anatomy consisting of convex ridges, concave grooves and a deep central pit.
The combination of deep anatomy and projecting ridges is important for the proper functioning of the tooth, and places less stress on the tooth root.

[0003] Currently dental laboratories use a lathe for the polishing of the crown or dental appliance. Such lathes use a polishing disc brush made of rigid brushes which is mounted on a rotating shaft. The edge of the rotating disc contacts the surface of the crown. Since the radius of the disc is necessarily too great for the disc to enter the pit, it is generally not possible to polish the depth of the pit without wearing down the surrounding anatomy. Similarly the disc cannot reach all parts of the grooves and ridges without wearing down the anatomy of the crown, which is undesirable. There is therefore a need for a device for polishing crowns, bridges or dental appliances which preserves the anatomy of the crown.
Summary of Invention [0004] The present invention provides a device for polishing a workpiece having a convoluted surface comprising: a brush-supporting member; an electric motor for imparting an orbital motion to the brush-supporting member; and a polishing brush comprising a curved working surface mounted on the brush-support-ing member. According to one aspect, the brush has a hemispherical face. The hemispherical face preferably faces vertically downwardly. The device may have a horizontal base, and may comprise a vertical motor support. The motor may be mounted within a motor housing on said vertical motor support. Preferably the brush-supporting plate extends downwardly from said motor housing and the device preferably has a plurality of brushes mounted on said brush-supporting plate.
Brief Description of Drawings [0005] In drawings which illustrate a preferred embodiment of the invention:

[0006] Fig. 1 is a perspective view of the surface of a crown;

[0007] Fig. 2 is a perspective view of the polishing device according to the invention;

[0008] Fig. 3 is a side view of the invention;

[0009] Fig. 4 is a detail of the polishing brushes of the invention with the brush housing removed for ease of illustration;

[0010] Fig. 5 is a view with the housing removed to better illustrate the orbital motor;

[0011] Fig. 6 is an enlarged perspective view of a brush head; and [0012] Fig. 7 is a partial sectional view of the brush head shown in Fig. 6.
Description [0013] Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0014] With reference to Figure 1, a crown 10 is shown, which may be of a precious metal such as gold alloy, or porcelain or acrylic. It has a convoluted upper or functional surface 12 having a marginal ridge 14, buccal cusp 16, lingal cusp 18, triangle ridges 20, groove 22 and pit 24. These complex features of the functional surface are referred to as the anatomy.

[0015] The polishing device 30 of the invention is shown in Fig. 2 through 5. It has a base 32, source of electrical power 34, switch 36, vertical post 38, and machine housing 40. Attached to machine housing 40 is a brush housing 42.
Extending downwardly from brush housing 42 is at least one, and preferably three or more brush heads 44, 46, 48. Brush heads 44, 46, 48 are formed of polishing brush filaments such as those used to form existing lathe polishing brushes.
Each brush head has a different profile according to the different desired tasks.
Prefera-bly the heads of the brushes have curved, generally hemispherical, faces with different radii to allow polishing of different surfaces. Also, providing multiple brush heads allows the use of a different coarseness of polishing compound on each brush head, from coarse to fme. The polishing compound is poured into openings 68 of each container 60, which are supported by support 64, and then reaches the brush through a tube 62 which connects each container 60 to the brush through hole 70 (Fig. 6 and 7) of each brush head.

[0016] Brushes 44, 46, 48 are mounted on brush plate SO (Fig. 5) which extends downwardly from and is secured to plate 52 of orbital motor 54. Brush plate 50 extends down a sufficient depth so that a technician working at the device can see the surface of the workpiece. A suitable motor 54 is from a Random Orbit Sander or Finishing Sander such as Makita Finishing Sander model B04552K. This is a sander in which a point on the sanding surface randomly orbits in a plane about a fixed center point Thus a point on the surface of the sander (such as the brush head in this case) follows a continuous random motion in a closed path such as a circle or an ellipse in a path around a center point in that plane. Such orbital motion, like the motion of a planet around the sun, is distinguished from rotational motion, such as the spinning of a planet on its own axis. The switch 36 turns the motor on and off without speed variability. A motor having a variable speed may also be used, although a variable speed is normally not required.

[0017] In operation, the technician having a gold crown to polish turns on the orbital motor 54 which imparts to brush heads 44, 46, 48 a rapid orbital motion, much as in an orbital sander. The technician then selects the brush with the appropriate radius and/or polishing compound and contacts the surface of the crown, thereby polishing it. Unlike the prior polishing devices, the anatomy of the crown is not thereby reduced.

[0018] While the invention has been described for purposes of polishing crowns, bridges and dental appliances such as dentures, the invention is useful for polishing any non-planar surfaces and particularly non-planar surfaces with complex or convoluted curvatures, including jewellery, small die-made parts and computer chips.

[0019] As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof.
Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.

Claims (17)

WHAT IS CLAIMED IS:

1. A device for polishing a workpiece, said workpiece comprising a convoluted surface, said device comprising:
a) a brash-supporting member, b) a polishing brush comprising a convex working surface mounted on said brush-supporting member;
c) a motor for imparting an orbital motion to said brush-supporting member whereby each point on said convex working surface of said polishing brush is imparted an orbital motion substantially within a plane and all said planes of motion of said points are parallel; and wherein said device is configured to permit a selected portion of said convoluted surface of said workpiece to be brought selectively into and out of contact with said working surface of said polishing brush.

2. The device of claim 1 wherein said brush-supporting member comprises a plate.

3. The device of claim 1 wherein said motor is housed in a housing and said brush-supporting member comprises a plate extending downwardly from said housing.

4. The device of claim 1 wherein said convex working surface is generally conical.

5. The device of claim 3 wherein said convex working surface comprises a generally hemispherical face.

6. The device of claim 5 wherein said generally hemispherical face faces downwardly from said housing.

7. The device of claim 5 further comprising a base for standing the device on a supporting surface.

8. The device of claim 7 further comprising a housing support for supporting said housing on said base.

9. The device of claim 1 wherein said convex working surface has a radius less than the transverse width of said workpiece.

10. The device of claim 1 comprising a plurality of polishing brushes mounted on said brush-supporting member.

11. The device of claim 10 wherein each said polishing brush includes a brush head having a convex working surface, each said brush head having a different radius.

12. The device of claim 1 wherein said workpiece is a dental appliance.

13. The device of claim 1 wherein said workpiece is a piece of jewellery.

14. The device of claim 1 further comprising a vertical motor support

15. The device of claim 14 wherein said motor is mounted within a motor housing on said vertical motor support and said brush-supporting member extends downwardly from said motor housing.

16. The device of claim 1 further comprising a container for polishing com-pound communicating with said polishing brush.

17. The device of claim 16 wherein said container communicates with said brush head by a tube extending to said polishing brush.