FIELD OF INVENTION

This invention relates to an improved diamond bur for use in prosthodontics. BACKGROUND OF INVENTION

Dental burs are widely used in tooth restoration. They are commonly used to cut away and abrade or polish parts of a tooth or restoration. A bur consists of a head, neck and shaft and is mounted in a dental hand piece (dental drill). The head holds the cutting or polishing surface and is the part of the bur that comes in contact with the tooth or restoration. The shaft is of standard shape and diameter to fit into the hand piece.

The head comes in a variety of sizes, surfaces and shapes. It is the part of the bur that is in contact with the tooth. It can be coated with an abrasive surface such as diamond. The neck is of size and shape to allow the shaft and the head to be functionally connected. The problem with prior art is that the diameter of the neck and shaft are too big to allow safe drilling or polishing at close proximity to adjacent teeth.

SUMMARY OF INVENTION

The object of this invention is to provide a means of preparing for a restoration without the risk of damage to the adjacent teeth. The device is a dental diamond bur for use during tooth restoration, specifically for shaping the tooth inter-proximally before crown fitting. In a first embodiment of the device, a dental bur has a neck member having a diameter smaller than the shaft member and a head member consisting of a diamond coated, abrasive portion and an uncoated, non-abrasive guidance tip with a diameter significantly smalier than the abrasive portion. In a second embodiment of the device, a dental bur has a neck member having a diameter smaller than the shaft member and a head member consisting of a diamond coated, abrasive portion and an uncoated, non-abrasive guidance tip with a diameter slightly wider than the widest part of the abrasive portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a side elevation view of a first embodiment of the present invention.

Figure 2 shows a cross-section view taken along section line 2-2 in Figure 1.

Figure 3 shows a cross-section view taken along section line 3-3 in Figure 1.

Figure 4 shows a cross-section view taken along section line 4-4 in Figure 1.

Figure 5 shows a cross-section view taken along section line 5-5 in Figure 1.

Figure 6 shows a cross-section view taken along section line 6-6 in Figure 1.

Figure 7 shows a side elevation view of a second embodiment of the present invention.

Figure 8 shows a cross-section view taken along section line 8-8 in Figure 7.

Figure 9 shows a cross-section view taken along section line 9-9 in Figure 7.

Figure 10 shows a cross-section view taken along section line 10-10 in Figure 7.

Figure 1 1 shows a cross-section view taken along section line 1 1-11 in Figure 7.

Figure 12 shows a cross-section view taken along section line 12-12 in Figure 7.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention relates to dental burs for use in restorative dental and prosthodontic procedures, namely, for cutting, abrading and polishing a tooth, dental crown and filler material, i.e. composite or resin, used in the procedure. Figures 1-12 show a first and second embodiment of the present invention. In operation of the devices shown in these figures the tooth and dental crown are prepared and fitted in any suitable manner known in the art.

Turning to Figures 1-6, a first embodiment of the inventive dental bur 10 is shown. The dental bur 10 comprises a shaft member 12, the shaft member 12 having a length L1. The shaft member 12 has a substantially uniform cross-sectional area CSA1 (Figure 2) along its entire length L1. A neck member 14 extends from the shaft member 10, the neck member 14 having a length L2, a first end adjacent the shaft member 10 and a second end opposite the first end. L2 is preferable more than 7 mm. A ramped connecting member may be present between the shaft member and neck member. The neck member 14 has a substantially uniform cross- sectional area CSA2 (Figure 3) along its entire length L2. The cross-sectional areas CSA1 and CSA2 are substantially concentric and CSA2 is less than CSA1. Alternatively, CSA1 and CSA2 can be of equal value.

A head member 16 is adjacent the second end of the neck member 14 and includes an abrasive portion 18, preferably coated with diamond grit, and an uncoated, non-abrasive guidance tip 20 adjacent to and concentric with the abrasive portion 18. The head member 18 is generally configured to adapt to the natural shape of the tooth undergoing the dental procedure. The abrasive portion 18 preferably has a length of less than 1.9 mm and the uncoated, non-abrasive guidance tip preferably has a length less than 1.0 mm. The abrasive portion 18 has a widened portion 22 (Figure 4) adjacent the neck member 14 with a generally circular cross-section and a radius R1 that is preferably iess than 0.7 mm (Rmax). The abrasive portion 18 has a narrowed portion 24 (Figure 5) also with a generally circular cross-section CSA3 and radius R2 that is preferably less than 0.25 mm (Rmin). As R1 is not equal to R2 and in this embodiment R1 is greater than R2, the abrasive portion 18 generally tapers inwardly from neck member 14 towards the non-abrasive guidance tip 20. The uncoated, non-abrasive guidance tip 20 terminates at a substantially planar end 26 and is generally circular in cross- section CSA5 (Figure 6) along its entire length, resulting in a cylindrical configuration. Radius R3 is less than R2 and is preferably less than 0.25 mm. CSA5 is preferably less than CSA3. In an alternative embodiment R2 and R3 can be equal in value.

in the embodiment shown in Figures 1-6, the shaft member 12 and neck member 14 are both cylindrical. The neck member 14 has a diameter D1 (Figure 3) and the shaft member 12 has a diameter D2 (Figure 2) where D1 is less than D2. D1 is selected to enable the neck member 14 to pass in the inter-proximal space between the tooth that is subject to the dental procedure and an adjacent tooth and is preferably less than 1.2 mm. D2 is selected to be a standard size for mating the shaft member 12 and dental bur 10 to a dental hand piece (not shown).

During the preparation of a tooth abutment, the shaping of the mesio-distal surfaces of the abutment poses significant risk of damage to the adjacent teeth. The smaller neck member diameter D1 of the inventive dental bur 10 allows easier access to the inter-proximal space between the tooth subject to the procedure and adjacent teeth. The shape of the head member 16 facilitates the shaping of the abutment, while the uncoated, non-abrasive guidance tip 20 allows the dentist to guide the dental bur 10 against and around the tooth, reducing the risk of touching the adjacent teeth with the neck member 14.

Figures 7-12 show a second embodiment of the present invention. Like reference numbers will be used for the same elements in this embodiment. The dental bur 10 comprises a shaft member 12, the shaft member 12 having a length L1. The shaft member 12 has a substantially uniform cross-sectional area CSA1 (Figure 8) along its entire length L1. A neck member 14 extends from the shaft member 10, the neck member 14 having a length L2, a first end adjacent the shaft member 10 and a second end opposite the first end. L2 is preferable more than 4 mm. The neck member 14 has a substantially uniform cross-sectional area CSA2 (Figure 9) along its entire length L2. A ramped connecting member may be present between the shaft member and neck member. The cross-sectional areas CSA1 and CSA2 are substantially concentric and CSA2 is less than CSA1. Alternatively, CSA1 and CSA2 can be of equal value.

A head member 16 is adjacent the second end of the neck member 14 and includes an abrasive portion 18, preferably coated with diamond grit, and an uncoated, non-abrasive guidance tip 20 adjacent to and concentric with the abrasive portion 18. The head member 18 is generally configured to adapt to the natural shape of the tooth undergoing the dental procedure. The abrasive portion 18 preferably has a length of less than 3.5 mm and the uncoated, non-abrasive guidance tip preferably has a length less than 1.0 mm. The abrasive portion 18 has a widened portion 22 (Figure 11) adjacent the non-abrasive guidance tip 20 and with a generally circular cross-section CSA4 and a radius R1 that is preferably less than 0.7 mm (Rmax). The abrasive portion has a narrowed portion 24 (Figure 10) also with a generally circular cross-section and radius R2 that is preferably less than 0.25 mm (Rmin). As R1 is not equal to R2 and in this embodiment R1 is less than R2, the abrasive portion 18 generally tapers outwardly from the neck member 14 towards the non-abrasive guidance tip 20. The uncoated, non-abrasive guidance tip 20 is a cylindrical disc that terminates at a substantially planar end 26 and has a radius R4 and generally circular cross-section CSA5 (Figure 12). Preferably radius R4 is greater than R1 and CSA5 is greater than CSA4. In an alternative embodiment R4 and R1 are equal in value.

In the embodiment shown in Figure 7, the shaft member 12 and neck member 14 are both cylindrical. The neck member 14 has a diameter D1 (Figure 9) and the shaft member 12 has a diameter D2 (Figure 8) where D1 is less than D2. D1 is selected to enable the neck member 14 to pass in the inter-proximal space between the tooth that is subject to the dental procedure and an adjacent tooth and is preferably less than 1.2 mm. D2 is selected to be a standard size for mating the shaft member 12 and dental bur 10 to a dental hand piece (not shown).

In operation, once a crown is fitted and the cement is cured, the dental bur 10 of Figure

7 is used to remove excess composite and to polish and finish the restoration. The smaller neck member diameter D1 of the dental bur 10 allows the neck member 14 to travel through the inter-proximal space between the tooth being restored and adjacent teeth, resulting in 360° access to the tooth being restored. The shape of the head member 16 mimics the natural tooth wall shape and when used, the non-abrasive guidance tip 20 allows the denttst to guide the dental bur 10 against and around the lower portion of the restoration, the remaining natural tooth, and polish and finish only the cement and ceramic crown.

While the present invention has been described in connection with a specific application, this application is exemplary in nature and is not intended to be limiting on the possible applications of this invention. It will be understood that modifications and variations may be effected without departing from the spirit and scope of the present invention. It will be appreciated that the present disclosure is intended as an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated and described. The disclosure is intended to cover, by the appended claims, all such modifications as fall within the scope of the claims.