Patent Description:
Dentists often use angled-head rotary cleaning devices known as "prophy" (prophylaxis) angle pieces with a longitudinal neck portion and a head portion that is angled relative to the neck. The angled head terminates into or holds a rotary tool which is dipped into a cleaning paste or other treatment material and then applied to a patient's teeth at a variable rotational speed. The rotary tool is most commonly a relatively soft "cup" used to apply paste or treatment material but different types of such cleaning tools are known for different purposes, such as brushes and rubber points.

At its rear end, the neck portion is coupled to a driving component which can be a motor handpiece or an adapter element for coupling the neck portion with a motor handpiece wherein a rotary movement provided by the driving component is transferred to the cleaning tool located at the neck portion by means of transmission elements accommodated in the neck portion and/or the head portion.

Usually, such cleaning devices as explained above are provided as disposable devices, i.e., they are intended for single-use and will be discarded afterwards. In this way, a complex cleaning and sterilization of the devices can be avoided. Consequently, production costs for these devises is a significant factor and, therefore, prophy angle pieces are often made from plastic and manufactured by injection molding.

On the other hand, dental treatment of requires a good visibility of the area to be treated. It is thus generally known that more complex treatment devices like reprocessable straight and contra-angle handpieces comprise a light source which is adapted to emit light in the region just in front of the treatment tool, e.g. in the direction of the tip of a dental drill. However, the production of such reprocessable straight and contra-angle handpieces is more complex and cost intensive such that integrating a light source in the headpieces does no significantly influence the production costs.

In this regard, <CIT> discloses a prophy angle piece wherein an LED is attached to a front portion of the neck to provide a treatment light. Cables providing an electrical connection to driving component are arranged within the interior of the sleeve-like neck portion. As an alternative solution, a fibre optic element is arranged within the neck portion running from the rear end to a region close to the head portion wherein the fibre optic element transmits light provided by the driving component to the light emitting end again to provide a treatment light.

However, also the solutions of <CIT> significantly complicate the productions of these prophy angle pieces resulting in increased productions costs. Thus, there is a need for of operating a disposable prophy angle piece with light, as is possible with reprocessable straight and contra-angle handpieces, wherein the productions costs of these devices can be kept as a reasonable level.

Further in the prior art, <CIT> discloses dental handpieces having an elongated neck portion and a head portion wherein at least one channel is contained in the handpiece. This at least one channel can be used for example as a light guide, for power supply or as a supply channel, for example for operating an air pressure turbine, which is located in the head portion. The handpiece is manufactured by arranging the required channels in their intended position and then casting plastic around the channels in a mold provided for this purpose.

Further, <CIT> discloses a dental handpiece having a head portion for receiving a tool, a rear sleeve portion for connecting to a handle portion having a drive, and a body connecting the head portion and the sleeve portion. The body consists of a metal sleeve which is hollow so that inside mechanical components can be arranged which are designed to transmit a rotation of the drive of the handle part to the tool located on the head portion. The metal sleeve is partly encapsulated with plastic to improve it's grip.

Finally, <CIT> discloses a head for a dental contra-angle handpiece having an operating shaft wherein the head is coupled to the operating shaft in the vicinity of the bend of the contra-angle. The head is produced from a synthetic material and accommodates a longitudinal light guide.

The above-mentioned problem is solved by the invention as defined in the independent claims. Preferred embodiments of the present invention are subject matter of the dependent claims.

According to the present invention, a light guiding element is used to transfer light provided by a driving component to a position close to the head portion. Light enters the light guiding element at its rear end and is guided to a light exit portion, which emits the light in such a way that the region around the cleaning tool of the device is illuminated. The light guiding element is held by the neck portion via a form-locking connection, wherein the light guiding element is formed by a separate element which is snap-fittingly attached to the neck portion. By accommodating at least a portion of the light guiding element in the wall of the neck portion, thus use of a separate fibre optic element which has to be separately arranged within the cleaning device can be avoided which makes the assembly and production of the cleaning device lees complex resulting in reduced production costs.

Accordingly, in line with the present invention, an angled-head rotary cleaning device for dental purposes is provided comprising a housing which is made from plastic and forms an elongated neck portion and a head portion located at a first end of and being angled relative to the neck portion,.

Using the light guiding element and accommodating at least a portion of it in the wall of the neck portion results in several advantages compared to the use of a fiber optic element. At first, the light guiding element, which is made from a transparent plastic material and is preferably formed by injection molding, can be optimized with respect to the light entry portion, the light guiding portion and the light exit portion. In contrast to the fiber optic element, no separate or additional optical elements are required to ensure efficient light injection and light emission, since the light guiding element itself can already be designed to be optimized in this respect. Further, integrating the light guiding element in the wall of the cleaning device can be achieved much easier than separately arranging the fiber optic within the neck portion.

Preferably, the light guiding element is elongated in a longitudinal direction of the cleaning device and is positioned on a bottom side of the cleaning device, which is where the cleaning tool being provided at the head portion. In this way, the light exit portion can be arranged to provide the maximum available light for illumination the cleaning tool.

Preferably, the light guiding element integrates into the outer geometry of the neck portion allowing leaving the outer geometry of the cleaning device as unchanged as possible. This results in the advantageous retention of the known ergonomic outer contour of such devices.

As the light guiding element is attached to the neck portion by the form-locking connection mentioned above, the light guiding element preferably also serves to lock the drive axis of the cleaning device. Accordingly, the light guiding element can comprise a catching porting facing towards the interior of the neck portion which catching portion is adapted for axially fixing a transmission element extending through the neck portion. In this situation, the light guiding element performs two functions at once, i.e. transmitting the light to the cleaning tool and fixing the transmission element. In this way, the number of components forming the inventive cleaning device can be kept at a minimum level.

The light guiding element can be made of a light conducting material, preferably a light conducting thermoplastic material like PMMA or PC, and has a length of <NUM> +<NUM>/-<NUM>. In an alternative solution, the light guiding element has a length that the light entry portion flushes with the rear end of neck portion. In a further alternative solution, the light guiding element ends in a recessed light in-coupling portion of the housing of the cleaning device. Finally, the wall of the neck portion could comprises a short channel portion close to the coupling region in which the rear end of light guiding element is inserted during the mounting process.

According to a further preferred embodiment of the present invention, the light entry portion of the light guiding element is adapted to co-operate with a connecting portion of the driving component for securing the cleaning device against rotation with respect to the driving component. This can be achieved by providing a light guiding element wherein the light entry portion forms a protrusion or a recess, which is adapted to engage with a corresponding recess or protrusion, provided at the driving component. Again, the light guiding element not only serves to transmit light by provides additional functionality resulting in a reduced number of individual parts.

For receiving the rotary movement provided by the driving component, the transmission element accommodated in the neck portion preferably comprises an elongated driving shaft having at its rear end a pin-like coupling portion, which is adapted to co-operate with a clamping mechanism of the driving component. The resulting structure of the coupling mechanism is extremely simple at least with respect to the side of the cleaning device. Again, this helps to keep the productions costs of the cleaning device at the desired low level.

The present invention also provides a dental cleaning system comprising an angled-head rotary cleaning device as explained above and a driving component adapted to removably couple with the cleaning device to provide a rotary movement, which is transmitted to the cleaning device, wherein the driving component comprises means for providing light to the light guiding element of the cleaning device.

According to the present invention, the driving component can be a motor handpiece comprising a motor, preferably an electric motor, for driving the rotary driving shaft, wherein the motor handpiece is directly coupleable with the cleaning device and comprises a light source facing towards the light entry portion of the light guiding element of the cleaning device. Alternatively, the driving component can be an adapter element, said adapter element being coupleable with a first end to the cleaning device and with a second end with a motor handpiece providing a rotary movement, wherein the adapter element comprises transmission elements for transmitting the rotary movement provided by the motor handpiece to the cleaning device. In this second alternative solution, the adapter element comprises a light source being located at the first end for providing light directly to the light guiding element of the cleaning device or a light guide facing with one end towards the motor handpiece for receiving light provided by a light source of the motor handpiece and facing with a second end towards the light entry portion of the light guiding element of the cleaning device.

In the following, the invention will be explained in more detail with reference to the enclosed drawings.

<FIG> generally shows a dental cleaning system based on a so-called disposable prophy angle (DPA for short) as it is known in the prior art. The system as shown in <FIG> comprises three main components, a motor handpiece <NUM>, an adapter element <NUM> and the DPA forming an angled-head rotary cleaning device <NUM>.

Motor handpiece <NUM> is a longitudinal, generally cylindrical handpiece component comprising internally an electric motor providing a rotary movement. Motor handpiece <NUM> can comprise internal power supply components like batteries or accumulators or alternatively can be connected to an external power supply via a cable, which is not shown in the drawings. The electric motor provides rotary movement with variable speed, which is transmitted to a cleaning tool <NUM> located at the front end of cleaning device <NUM>.

In many solutions known from the prior art, the cleaning device <NUM> is not directly coupled to the motor handpiece <NUM>, but an intermediate component is used as an adapter. <FIG> also shows such an adapter element <NUM>, which is coupled at its rear end to the motor handpiece <NUM> and at its front end to the cleaning device <NUM>. The adapter element <NUM> is preferably designed in accordance with the provisions of DIN EN ISO14457 and enables flexible connection of different cleaning devices to the motor handpiece <NUM>, whereby the rotary movement provided by the motor handpiece <NUM> is transmitted to the cleaning device via internal transmission elements. As a further advantage resulting from the use of the adapter element <NUM>, the distance between the motor handpiece <NUM> and the cleaning device <NUM> is increased. This is an important aspect, as the cleaning device <NUM> should be the only component in direct contact with a patient. As mentioned above, the cleaning device <NUM> is designed as a disposable device that is disposed of after use, whereas the motor handpiece <NUM> is used multiple times, but must be cleaned and/or sterilized through a complex reprocessing process. Therefore, contamination of the motor handpiece <NUM> should be avoided.

In general, it is desirable to improve the visibility of the area treated by the cleaning device <NUM> by directing light to the corresponding area. In the prior art, it is known from <CIT> to integrate an LED in the cleaning device <NUM>, which is supplied by the motor handpiece <NUM> via cables that extend through the cleaning device <NUM> and have connection sections suitable for coupling with corresponding connections on the motor handpiece. The present invention provides a more economical solution that still allows light to be efficiently directed to the front area of the cleaning tool <NUM>, however the cleaning device <NUM> can be manufactured at a lower cost.

The general idea of the present invention is to use a light guiding element, which is integrated in cleaning device <NUM> and transmits light received from a driving component to a light exit portion in such a way that light is directed to cleaning tool <NUM>.

<FIG> show three general alternatives to achieve illumination of the treatment area in accordance with the present invention, which differ with respect to the location of the primary light source.

In the embodiment shown in <FIG>, the cleaning system again comprises the three components, i.e. motor handpiece <NUM>, adapter element <NUM> and angled-head rotary cleaning device <NUM>. Here, a light source preferably formed by an LED <NUM> is provided at motor handpiece <NUM>. In particular, LED <NUM> is provided at the front end of motor handpiece <NUM> in the area of a coupling portion being adapted to couple with the rear end of adapter element <NUM>. Light generated by LED <NUM> is transferred via a first light guide <NUM> to the front portion of adapter element <NUM>. When coupled with cleaning device <NUM>, light forwarded by light guide <NUM> enters a light entry portion <NUM> of the inventive light guiding element <NUM>, which finally emits light at its light exit portion <NUM>, which is positioned close to the head portion <NUM> of cleaning device <NUM>, which is where cleaning tool <NUM> is located.

In <FIG>, again intermediate adapter element <NUM> is used to transmit rotary movement provided by motor handpiece <NUM> to cleaning device <NUM>. Now, a light source <NUM>, which is again formed by an LED, is provided at adapter element <NUM>, in particular at the front coupling portion of adapter element <NUM>, which connects to the rear portion of cleaning device <NUM>. Similar to the solution of <FIG>, a light guiding element <NUM> is integrated in cleaning device <NUM> wherein light generated by LED <NUM> enters light guiding element <NUM> at its light entry portion <NUM> and it is then forwarded to and emitted at light exit portion <NUM> of light guiding element <NUM>. In this case, the adapter element <NUM> must comprise electrical connection components, which connect to motor handpiece <NUM> in order to provide power for driving the LED <NUM>.

Finally, <FIG> shows a solution where the adapter element <NUM> is omitted and the cleaning device <NUM> is directly coupled with motor handpiece <NUM>. Here, the length of cleaning device <NUM> is increased compared to the two solutions shown in <FIG> in order to ensure that again head portion <NUM> of the cleaning device <NUM> is separated from the motor handpiece <NUM> by a sufficient distance. In this solution, the primary light source is again an LED <NUM> arranged at the coupling portion of motor handpiece <NUM> and a light guiding element <NUM> extending from the rear end of cleaning device <NUM> to a front portion close to the head portion transfers the light in order to illuminate the region of the cleaning tool.

It has to be mentioned that <FIG> schematically show the general concept of the present invention of using a light guiding element <NUM>, which is integrated in cleaning device <NUM> and transfers a light provided by a driving component (which can be the motor handpiece <NUM> or adapter element <NUM>) to the region where the cleaning tool <NUM> is located. The present invention in particular makes use of specific integration techniques allowing reducing production costs for cleaning device <NUM> while at the same time an efficient light transmission can be achieved. Several embodiments of the three alternative solutions will be explained in more detail in the following.

A first preferred embodiment is shown in <FIG>, wherein an angular head rotary cleaning device <NUM> is coupled to an adapter element <NUM>. As known from the prior art, the adapter element <NUM> has the main function of transmitting a rotary motion provided by a motor handpiece - not shown - to the cleaning device <NUM> in order to rotate the cleaning tool <NUM>. The transmission within the cleaning device <NUM> is performed by means of an elongated transmission element <NUM> extending through a sleeve-shaped neck portion <NUM> of the housing <NUM>. A second rotary element <NUM> is arranged at the head portion <NUM> of the cleaning device <NUM>, which couples to the transmission element <NUM> via an angular gear and carries the cleaning tool <NUM> at its front end. All components of the cleaning device <NUM> are preferably made of plastic, which enables a reduction in material costs. The rear end portion of the transmission element <NUM> forms a pin-shaped coupling portion <NUM>, which extends into adapter element <NUM> and engages with a clamping mechanism of the adapter element <NUM> to enable transmission of motion.

In this first embodiment, the adapter element <NUM> carries at its front portion at least one light source <NUM> configured to be coupled to the cleaning device <NUM>. The light source <NUM> may be positioned over the entire radius of the cylindrical coupling section and thus be annular in shape. Preferably, the light source is implemented in the form of a single LED forming a point light source. The LED <NUM> can have any color or be an ultraviolet LED, but is preferably realized in the form of a white light LED. The light source <NUM> and in particular its direction of emission are directed towards the cleaning device <NUM>, preferably at a defined angle α between <NUM>° and <NUM>° with respect to the axis of rotation I, in order to improve the transmission of the light to the light guiding element <NUM>. This will be explained in more detail later.

The LED <NUM> is soldered onto a surface of a carrier portion of adapter element <NUM>, preferably onto a bevelled surface (see <FIG>). A 3D-MID carrier <NUM> is preferably used and the LED <NUM> is contacted by electrically conductive components. It is particularly advantageous that the 3D-MID carrier <NUM> carries the electrical contacting of the LED <NUM> and the required electrical conductors. The electric contact is routed to an interface facing away from the cleaning device <NUM> via the electrical conductors. This is preferably done via pockets or grooves recessed in the wall of adapter element <NUM>. The pockets extend over the entire length of the 3D-MID carrier <NUM> and the carrier is primarily rotationally symmetrical. On one, preferably eccentrically offset, surface of the carrier <NUM> a component <NUM> can be integrated which serves to detect the electric coupling with the LED <NUM>. A resistor can be used for this purpose, which is preferably connected in parallel to the LED.

The outer sleeve <NUM> of adapter element <NUM> is primarily rotationally symmetrical and has an opening and a groove for the light exit. This opening is approximately round and serves to ensure the light emission. The groove is designed in such a way that the cleaning device <NUM> can dip onto the outer sleeve when it is plugged on, in order to achieve the smallest possible distance between the LED <NUM> and the light entry portion <NUM> of light guiding element <NUM>. Preferably, an elevation <NUM> attached to the light guiding element <NUM> dips into this groove during the plug-in process. In this way, a pre-centering of the cleaning device <NUM> with respect to the coupling element <NUM> is achieved and the cleaning device <NUM> is secured against a rotational movement with respect to adapter element <NUM>. This results in the positive effect that the location of the light entry portion <NUM> of light guiding element is precisely defined with respect to LED <NUM>.

The inventive angled-head rotary cleaning device <NUM> contains the light guiding element <NUM> on the lower side facing the cleaning tool <NUM>, which is located at the head portion <NUM>. The light guiding element <NUM> is geometrically designed to integrate into the outer geometry of the longitudinal neck portion <NUM> and has a light exit portion <NUM> at its front end near the cleaning tool <NUM>. In the shown embodiment, a light exit is preferably affected by the continuation of the light guiding element <NUM> at an angle such that the light is emitted from the outer contour of the wall <NUM> of neck portion <NUM>. Preferably, the angle is <NUM>° +/- <NUM>° relative to the axis of rotation I. The light exit portion <NUM> then closes the outer geometry of the cleaning device <NUM> in the direction to the cleaning tool <NUM>.

The light guiding element <NUM> is shown in more detail in <FIG> showing in particular the light entry portion <NUM> and the light exit portion <NUM>. As already mentioned, the light guiding element <NUM> has an elevation <NUM> in the direction of the axis of rotation I at the light entry portion <NUM> which serves to secure the cleaning device <NUM> against rotation with respect to adapter element <NUM>. This elevation <NUM> also forms a lens with a preferably convex shaped light entry surface <NUM> to improve the light entry into the light guiding element <NUM>.

As a further particular feature, the light guiding element <NUM> has an integrally formed catching portion <NUM>, which forms a part-cylindrical bearing surface, which engages an intermediate portion of the transmission element <NUM> located between two disc-shaped flange portions <NUM> and <NUM>. When the light guiding element <NUM> is attached to the housing <NUM> of the cleaning apparatus <NUM>, this catching portion <NUM> secures the transmission element <NUM> in the axial direction so that the front coupling portion of the transmission element <NUM> engages the second rotary member <NUM> to which the cleaning tool <NUM> is attached.

In the first embodiment shown in <FIG>, light guiding element <NUM> is connected to housing <NUM> of cleaning device <NUM> by a form-locking connection. As defined in the invention, the light guiding element <NUM> is snap-fittingly attached to the sleeve <NUM> form by the neck portion <NUM>. For production of cleaning device <NUM>, at first housing <NUM> is formed - preferably by injection moulding - and transmission element <NUM> and second rotary member <NUM> with the cleaning device <NUM> are inserted into the housing <NUM>. In a final production step, light guiding element <NUM> is attached to the housing <NUM> in order to complete the outer contour of cleaning device <NUM> and at the same time secure transmission element <NUM> against axial movement.

Preferably in addition to the latching of the catching portion <NUM> near the cleaning tool <NUM>, there is a further latching on the inside of the light guiding element <NUM> at the end remote from the cleaning tool <NUM> to ensure that the light guiding element is fixed at this point of the cleaning device. Preferably, this latch is released by a snap connection, which latches internally in the geometry of the outer sleeve.

The length of the light guiding element <NUM> is kept as short as possible to keep the transmission losses as low as possible. Furthermore, a short design increases the stability of the snap-fit connection and thus the fixation of the light guiding element <NUM> in the cleaning device <NUM>. For example, the light guiding element <NUM> has a length of <NUM> +<NUM>/-<NUM>. Is made of a light conducting material, preferably a light conducting thermoplastic material like PMMA or PC.

Accordingly, cleaning device <NUM> consists in total of only four separate elements which all can be manufactured in standard processes like injection moulding. Further, mounting of these four components can be realised in a fast and efficient way.

In the embodiment show in <FIG>, light entry portion <NUM> of the relatively short light guiding element <NUM> is located at in intermediate position in the longitudinal direction of neck portion <NUM>. In this case, the light source <NUM> of adapter element <NUM> is located in the front region of the cylindrical coupling element, which is inserted into the rear end of cleaning device <NUM> during the coupling process.

In an alternative solution shown in <FIG>, the longitudinal extension of light guiding element <NUM> is increased such that the light entry portion <NUM> more or less flushes with the rear end of neck portion <NUM>. This of course requires an adaptation of the location of the LED <NUM> of adapter element <NUM>, which then should be arrange at a corresponding surface portion facing towards the light entry portion of light guiding element <NUM>. The resulting cleaning device <NUM> with elongated light guiding element <NUM> is shown in <FIG>. In this case, the mechanical latching of the light guiding element <NUM> preferably does not take place at the point of light in-coupling but at an intermediate position.

A third design variant is shown in <FIG> wherein the length of light guiding element <NUM> is again increased compared to the embodiment shown in <FIG> but wherein the light guiding element <NUM> ends in an recessed light in-coupling portion of housing <NUM> of the cleaning device <NUM>. The recessing of the light guiding element <NUM> ensures that a corresponding protrusion provided at adapter element <NUM> can engage this recess allowing again to secure the cleaning device against rotation at the point where the light in-coupling takes place.

A fourth design variant is shown in <FIG> wherein the cleaning device <NUM> now is configured to directly couple with the motor handpiece <NUM> (not shown in <FIG>). This solution corresponds to the general alternative solution shown in <FIG> wherein the housing of cleaning device <NUM> is extended in longitudinal direction in order to increase the distance between cleaning tool <NUM> to the driving component. Again, as defined in the invention, light guiding element <NUM> is formed as an element, which is snap-fittingly attached to the wall <NUM> of neck portion <NUM>. In this case, the wall <NUM> of neck portion <NUM> comprises a short channel portion 16a close to the coupling region in which the rear end of light guiding element <NUM> is inserted during the mounting process. The front portion light guiding element <NUM> having again the catching portion <NUM> is then snap-fittingly attached to the neck portion <NUM> similar to the embodiments shown in <FIG>. In the solution shown in <FIG>, the separate adapter element <NUM> is not necessary and the number of components of the complete cleaning system is further reduced.

Again, the light transmission from the driving component to the cleaning device <NUM> can additionally be used to secure the cleaning device <NUM> against rotation. In this case, the light guiding element <NUM> ends in a slightly protruding latching lug that engages in a corresponding recess in an end face of the motor handpiece <NUM>, in which the LED is also arranged. A reversed configuration in which the LED of the motor handpiece <NUM> is arranged on a projection or latching lug would also be conceivable.

For all embodiments discussed so far, a form-fitting connection is used for attaching the light guiding element <NUM> to housing <NUM> of cleaning device <NUM> wherein, as defined in the invention, a snap-fitting connection is used. An alternative possibility to attach light guiding element <NUM> to cleaning device <NUM> is shown in <FIG>.

Here, the housing <NUM> clampingly holds the light guiding element <NUM>. This is achieved by providing two separate housing components <NUM> and <NUM> as shown in <FIG>, which form half shells of the housing <NUM> and are attached to each other during the mounting process to hold all internal components. In particular, at first transmission components <NUM>, <NUM> including the cleaning tool <NUM> are inserted into one of both half shells <NUM> and the second half shell <NUM> is then connected with the first half shell for example by specific clamping or ledging mechanism. In a similar way as transmission components <NUM> and <NUM>, also light guiding element <NUM> is now integrated in the wall <NUM> of neck portion <NUM>. In this case, both housing components <NUM> and <NUM> comprise corresponding longitudinal grooves 17a and 18a in their respective walls wherein the grooves 17a, 18a cooperate to form a channel for accommodating at least a portion of the longitudinal light guiding element <NUM>, preferably for accommodating the light guiding element <NUM> over its entire length.

In the solution shown in <FIG> and <FIG>, the structure of light guiding element <NUM> is less complex compared to the solution shown in <FIG> simplifying the production process. In particular, the diameter of the light guiding element <NUM> is in this embodiment constant over the whole length. However, as shown for example in <FIG>, also in this alternative solution the front portion close to the light exit portion <NUM> of light guiding element <NUM> can include a catching portion <NUM> which again serves to secure the longitudinal transmission element <NUM> within cleaning device <NUM>. Further, similar to the embodiments discussed above, the light entry portion <NUM> of light guiding element <NUM> can additionally serve to secure cleaning device <NUM> against a rotational movement. This is achieved by either providing the light guiding element <NUM> with a light entry portion <NUM>, which forms or is located in a protrusion engaging in a recess of the corresponding driving component <NUM> or <NUM> (<FIG>) or by arranging the light entry portion <NUM> in a corresponding recessed portion in which a protrusion provided at the driving component <NUM>, <NUM> engages (<FIG>). As shown by <FIG>, the cleaning device <NUM> can be provided either in the short configuration where the adapter element <NUM> is used for coupling with the motor handpiece <NUM> or in the elongated configuration for a direct coupling with the motor handpiece <NUM>.

Finally, a third option to integrate the light guiding element into the cleaning device is explained in connection with <FIG>. Here, a material-locking connection is used in which the light guiding element <NUM> is permanently attached to the housing <NUM> of cleaning device <NUM>.

A first solution for achieving such a material bond is illustrated in <FIG>, using a two-component plastic injection molding process performed in two stages. In this scenario, the housing <NUM> of the cleaning device <NUM> is first molded (<FIG>), leaving a channel <NUM> that is then filled with a second material that forms the light guiding element <NUM>. In order to maintain the channel <NUM>, certain slides <NUM> and <NUM> are arranged in the mold during the molding of the housing <NUM>, which are removed after the material forming the housing <NUM> of the cleaning device <NUM> has hardened (<FIG>). This creates a longitudinal cavity <NUM> which, in a second step (<FIG>), is filled with the material forming the light guiding element <NUM>.

As an alternative solution, it would also be possible to produce in a first step light guiding element <NUM>, then place light guiding element <NUM> within the mould for manufacturing the cleaning device housing <NUM> and moulding the cleaning device in a second step. Also by this over-moulding process, an integral and permanent connection between housing <NUM> and light guiding element <NUM> is obtained.

The light guiding element again can have similar features as light guiding element <NUM> explained in connection with the embodiments shown in <FIG> with the exception of the catching portion. However, again light guiding element is not only used to transfer light but also helps to improve the coupling to the driving component by additionally securing the cleaning device against rotation.

Claim 1:
Angled-head rotary cleaning device (<NUM>) for dental purposes comprising a housing (<NUM>) which is made from plastic and forms an elongated neck portion (<NUM>) and a head portion (<NUM>) located at a first end of and being angled relative to the neck portion (<NUM>), wherein a second end of the neck portion (<NUM>) is adapted to removably couple with a driving component (<NUM>, <NUM>) providing a rotary movement and wherein the neck portion (<NUM>) forms a sleeve (<NUM>) with a wall (<NUM>), the housing (<NUM>) accommodating transmission elements (<NUM>, <NUM>) for transferring a rotary movement from the driving component (<NUM>, <NUM>) to a cleaning tool (<NUM>) being provided at the head portion (<NUM>), wherein the cleaning device (<NUM>) further comprises an elongated light guiding element (<NUM>), said light guiding element (<NUM>) comprising a light entry portion (<NUM>) being positioned at the second end of the neck portion (<NUM>) for receiving light provided by the driving component (<NUM>, <NUM>) and a light exit portion (<NUM>) being positioned close to the head portion (<NUM>),
wherein at least a portion of the light guiding element (<NUM>) is accommodated within the wall (<NUM>) of the neck portion (<NUM>), and
wherein the light guiding element (<NUM>) is held by the neck portion (<NUM>) via a form-locking connection, the light guiding element (<NUM>) being formed by a separate element which is snap-fittingly attached to the neck portion (<NUM>).