Medical, in particular dental, contra-angle handpieces for driving a dental instrument connected to the contra-angle handpiece with shafts arranged in the contra-angle handpiece for the transmission of the drive movement to the instrument. In order to achieve a reduction of sound emission and a reduction of the manufacturing and assembly costs while still incorporating the curvature of the outer sleeve of the contra-angle handpiece and the advantages which this entails, the contra-angle handpiece is equipped with a single-piece shaft which is essentially centered at the proximal end and the distal end of the outer sleeve, but runs eccentrically in a section of the outer sleeve between the proximal end and the distal end. The curvature of the outer sleeve of the contra-angle handpiece is in the range of about 8° to about 16°, and in some implementations, in the range of about 10° to about 14°.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from pending Austrian Patent Application No. A 1090/2004, filed Jun. 28, 2004, which is incorporated herein by reference.

FIELD

The present application is concerned with medical, in particular dental, contra-angle handpieces for driving an instrument connected to the contra-angle handpiece with shafts arranged in the contra-angle handpiece for the transmission of the drive movement to the instrument.

DESCRIPTION OF PRIOR ART

Such a contra-angle handpiece is, for example, disclosed in AT 408.514 B. By contrast with straight handpieces, the outer sleeve of the contra-angle handpieces features a curvature, for the contra-angle handpieces submitted by the applicant preferably in the range of 18°-21°. For the user, this curvature is ergonomically advantageous and simplifies the viewing of the treatment site. The outer sleeve of the contra-angle handpiece contains, along with other equipment, the motor shafts, which transmit the drive movement of the respective drive unit, preferably an electric motor, to the instrument.

The disadvantage of such contra-angle handpieces is that, in order to overcome the curvature of the outer sleeve, in the area of their curvature the ends of the motor shafts must be connected by gearwheels. The manufacture and assembly of the shafts with the gearwheels is cost-intensive. Furthermore, during operation, due to the friction between the meshing gearwheels, losses occur in the transmission of the torque, as well as running noise, sensed by both the user and the patient as disturbing.

It would be beneficial to provide a contra-angle handpiece which still incorporates the curvature of the outer sleeve and the advantages which this entails while at the same time offering improved torque transmission, with reduced losses, reduced sound emission and less costly manufacturing and assembly.

SUMMARY

Disclosed below are representative embodiments that are not intended to be limiting in any way. Instead, the present disclosure is directed toward novel and nonobvious features, aspects, and equivalents of the embodiments of the contra-angle handpiece described below. The disclosed features and aspects of the embodiments can be used alone or in various novel and nonobvious combinations and sub-combinations with one another.

Surprisingly, a contra-angle handpiece with a single-piece shaft running through the entire contra-angle handpiece up to the head shaft, arranged in the head of the contra-angle handpiece, could be designed without having to eliminate the curvature of the outer sleeve. The single-piece shaft and, if necessary, the dog as a functional part of the single-piece shaft are essentially centered at the proximal end and the distal end of the outer sleeve, as compared with an eccentric arrangement in a section between the proximal end and the distal end. The curvature of the outer sleeve of the contra-angle handpiece is preferably in the range of about 8° to about 16°, with particular preference for the range of about 10° to about 14°.

In extensive practical trials, remarkably enough it could be demonstrated that implementations of a contra-angle handpiece offer the user the same advantages in terms of ergonomics and free viewing of the treatment site as the contra-angle handpieces known from the present state of the art. At the same time, a reduction of sound emission and improved torque transmission with low losses are achieved. Furthermore, the new contra-angle handpiece reduces the costs of manufacturing and assembly.

In a preferred embodiment, the center axis of the neck section of the outer sleeve and the center axis of the head enclose an angle of greater than or equal to about 90°, with a preferred value in the range of about 92° to about 95°, permitting greater convenience for the user in the handling of the contra-angle handpiece.

The foregoing and additional features and advantages of the disclosed embodiments will become more apparent from the following detailed description, which proceeds with reference to the following drawings.

DETAILED DESCRIPTION

The outer sleeve2of contra-angle handpiece1, inFIG. 1, is comprised of a handle3, a neck section4and a contra-angle handpiece head5. In the region of transition between the handle3and the neck section4, the outer sleeve2features a curvature6, which offers the user ergonomic advantages and also improved viewing of the treatment site.

In the contra-angle handpiece head5an instrument carrier7is arranged in a known manner as part of the head shaft22, supported by two bearings, preferably rolling bearings8(due to the only partly removed outer sleeve, only one bearing can be seen). The instrument carrier7has an opening9on one side for inserting a dental instrument, for example a dental drill (not shown). On the side opposite the opening9of the head5is a pushbutton10for releasing the dental instrument from the instrument carrier7.

At the proximal end2A of the outer sleeve2is a coupling device11for connecting to a drive unit, preferably an electric motor. For the transmission of the drive movement from the motor to the dental instrument, a coupling tenon (not shown) is arranged in a known manner at the distal end of the drive unit and led into the cavity12of the contra-angle handpiece1, so that the rotor shaft of the motor is connected to the shaft13of the contra-angle handpiece. The cavity12is formed by an enlargement of the inside diameter of the bearing sleeve17in its proximal section.

At the proximal end of the shaft13is a transverse bore18for taking up a straight grooved pin15. With the use of the straight grooved pin15, the dog14is connected to the shaft13. Pin15passes through two longitudinal slits19,20of the dog14. The spring16preloads the dog14against the shaft13and the bearing sleeve17. As a result of the two longitudinal slits19,20the dog14can be displaced parallel to the center axis21of the shaft13. This play ensures the secure coupling of the drive unit and the contra-angle handpiece1, as well as the reliable transmission of the rotational movement and the torque from the rotor shaft to the shaft13.

In some implementations, the transmission of the drive movement through the entire contra-angle handpiece1up to the head shaft22in the head5is implemented by one, single-piece rigid shaft13. The shaft13is arranged in the contra-angle handpiece1so that it and the dog14as a part and functional extension of the shaft13are essentially centered at the proximal end2A and at the distal end2B of the outer sleeve2. By contrast, at section2C of the outer sleeve2between the proximal end2A and the distal end2B the shaft13is eccentrically arranged, i.e., it is off center and positioned closer to one side. At the distal end of the shaft13is a gearwheel23, which meshes with a second gearwheel24of the head shaft22and transmits the drive movement to the head shaft22and the dental instrument fixed in the instrument carrier7.

The shaft13is supported by the likewise single-piece designed bearing sleeve17by means of two rolling bearings25,26. The distal end of the bearing sleeve17is supported at the inner wall of the outer sleeve2and the proximal end at a threaded ring27as a part of the coupling11.

The contra-angle handpiece100illustrated inFIG. 2corresponds in its design to the contra-angle handpiece1ofFIG. 1, so that it is not necessary to repeat the detailed description here.

By contrast withFIG. 1, the shaft13and the bearing sleeve17of the contra-angle handpiece100are comprised of several sections13A and13B and17A and17B, respectively, with different diameters. Section17A, with the smaller diameter, surrounds at least parts of section13A, with the smaller diameter. The respective sections13A and17A with the smaller diameters are in the region of the curvature6of the outer sleeve2, preferentially enabling greater curvature of the outer sleeve2. The shaft13and the bearing sleeve17can of course embrace more than two sections, with different diameters.

In addition,FIG. 2also gives information about the relevant angles between the individual components of the contra-angle handpiece100, which apply analogously for the contra-angle handpiece1illustrated inFIG. 1.

The center axis28of the handle3and the center axis29of the neck section4enclose an angle W1in the range of about 8° to about 16°, preferably in the range of about 10° to about 14°. The angle W1is that angle which describes the curvature6, important for the user. The angle W2is formed by the center axis29of the neck section4and the center axis30of the head5. The angle W2is greater than or equal to about 90°, preferably in the range of about 92° to about 95°. The angle of inclination W2of the head5in relation to the neck section4is in addition to the angle W1of curvature6, so that overall the contra-angle handpieces1and100offer the user the same advantages in terms of ergonomics and free viewing of the treatment site as the contra-angle handpieces known from the present state of the art.

The invention is not limited to the range of applications and the embodiments described, but contains all embodiments which do not entail changes of the fundamental character of the functional principle. Thus, for example, the term “single-piece shaft” also encompasses shafts comprised of several parts and preferably connected during assembly of the contra-angle handpiece, such as by form-fitting, in particular by a screw connection, so that the operation of the contra-angle handpiece is based on a functionally single-piece shaft without interconnected gearwheels or transmissions.