Adjustable dental tool drive arrangement

Abstract

The invention relates to an improved dental tool drive arrangement for a hand-piece with a drive head, the tool drive arrangement permitting length adjustment of the tool in the drive head by concentrically supporting the tool in the drive head at any position from a fully inserted position to a maximum retracted position. The tool drive arrangement preferably includes a tool and a rotatable tool supporting element for concentrically supporting the tool from the fully inserted to the maximum retracted position, the tool preferably including a maximum retraction indicator for indicating to a user when the tool has been retracted to the maximum retraction position. This provides a significant advantage over the prior art by allowing a user to adjust the exposed length of a rotatable tool, preferably a dental bur, without exceeding safe operating limits. The invention also relates to an improved drive spindle which allows depth adjustment of a tool in a dental handpiece while maintaining efficient torque transfer and concentricity during high speed rotation.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority from U.S. Application Ser. No. 60 / 689,052, entitled Dental Burr And Drive Spindle, filed Jun. 10, 2005, and from U.S. application Ser. No. 11 / 262,959, entitled Adjustable Tool Drive Arrangement, filed Nov. 1, 2005, which applications are included herein by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates generally to handpieces for rotating tools. More particularly, the present invention relates to an improved drive arrangement for a rotatable tool, including a drive spindle and the tool.BACKGROUND OF THE INVENTION[0003]Numerous handpieces for rotating tools exist. Turbine driven handpieces are widely used in dental offices and medical labs around the world. Most handpieces include a handle and drive head for supporting the rotating tool. A connector, often a swivel connector, connects the handpiece to various air, water, light and power supply conduits, generally combin...

AI Technical Summary

Benefits of technology

"The present invention provides a tool drive arrangement for a dental handpiece that allows for length adjustment of the tool without exceeding safe operating limits. The tool drive arrangement includes a tool supporting element and a tool driving head. The tool supporting element can concentrically support the tool in the drive head at different positions from a fully inserted position to a maximum retracted position. The tool driving head includes a drive spindle with a drive torque receiving portion and a tool retaining member for releasably retaining the tool. The maximum retraction indicator is a visible or mechanical indicia that indicates when the tool reaches its maximum retraction depth. The invention reduces the number of times a dentist needs to exchange tools for selection of different tool lengths during a dental procedure and avoids excessive wear and damage due to insufficient insertion of the tool in the handpiece."

Problems solved by technology

The known drive arrangements are not designed to allow for length adjustment of the tool, which means the tool, once fully inserted in the drive arrangement will always protrude the same length from the drive head.

However, as a dental procedure progresses, a dentist may need to use dental tools of different length.

This creates the need for repeated tool changes, which is time consuming and cost intensive, since a collection of different length tools must be purchased.

However, this adjustment is made without knowledge whether the bur will remain properly engaged within the drive mechanism and safely secured within the drive head.

This is a dangerous practice, since prior art handpieces are not designed to hold the bur in any position other than fully inserted into the drive head.

However, concentrical support of the tool within the drive head and reliable torque transmission from the drive to the tool are not ensured.

However, those friction arms are somewhat flexible by design and generally do not provide sufficient force to maintain the rear end of the tool concentrically aligned in the drive when lateral forces are applied to the working end of the tool during use.

Therefore, operation of a conventional handpiece at a tool insertion depth other than fully inserted can result in loss of concentricity, vibration of the bur during rotation, excessive wear, damage to the drive assembly, permanent deformation of the tool securing mechanism and drive spindle components, inefficient torque transfer, increased bur slippage (both rotational and axial), and most dangerously, accidental disengagement of the bur from the handpiece during use.

Only low torque transmission is possible between the chuck and the bur in such constructions, higher torque leading to slippage of the bur.

At the high rotational speeds achieved by modern dental handpieces, bur slippage, in both the axial and rotational directions, can become a problem.

Rapid deceleration of the bur can also lead to rotational slippage, for example, when the drive continues to rotate while the bur is locked or snagged.

Friction between the drive assembly and the dental bur during rotation leads to significant wear of both elements over time.

This friction can also produce significant heat, as can friction generated in push-button lock handpieces when the user maintains pressure on the push-button during operation.

Friction heat can cause permanent damage to the drive spindle components, especially the flexible friction arms of the chuck, which are normally made of heat tempered material.

The damage can lead to rotational slippage and even axial slippage of the tool, possibly resulting in an accidental release of the tool from the handpiece.

Accidental release of a dental bur during high speed rotation can pose a threat to both the patient and the dentist.

Continued wear of the bur and drive assembly during operation necessitates routine maintenance and repair of expensive handpiece components.

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