DESCRIPTION Technical field of the invention

The present invention relates to a powder cleaner for dental use, in particular of the type which dispenses a mixture under pressure of air and abrasive powder, typically together with a jet of water. Background

Powder cleaners are typically used in dentistry to remove tartar during dental hygiene. They are also used for the finishing of dental surfaces subsequent, for example, to a partial removal, or prosthetic operation.

Such cleaners perform precisely a superficial removal of material by dispensing a jet under pressure of air and abrasive powder. In general, the same instrument also administers a flow of water through a channel separate from that of the air and having a dispensing outlet adjacent or externally concentric to that of the air.

Known powder cleaners are in the form of a handpiece which can be grasped by an operator and can be connected to the sources or connections of compressed air and water generally present in dental laboratories. A commonly used type of device comprises a pair of oblong arms, in particular a proximal one with respect to the operator, which houses the connections for the above air and water connections, and a distal one which terminates with the dispensing outlets on the patient. Between these arms there is an intermediate chamber, generally spherical, which has an upper access to allow the loading of the powder therein.

The compressed air is conveyed into the above intermediate chamber, inside which a turbulence is generated which causes the air to be mixed with the powder and then the entrainment of the latter towards the outlet of the chamber in the dispensing direction to the patient.

One of the drawbacks of prior art cleaners is that each model of them is substantially specific for a type of abrasive powder in terms of mechanical properties and/or dimensions of the latter. In particular, on the market there are powders of various grain sizes, which can range from 120 microns up to 12 microns in diameter, or linear dimension, average of each particle. For optimal mixing and entrainment, each type of powders requires specific fluid-dynamic conditions inside the turbulence chamber which, in the prior art, are obtained for example by modifying the geometry of the chamber itself or by modifying the geometry of the nozzles contained in the chamber.

As a result, as mentioned, the manufacturers of powder cleaners provide different devices to cover the different grain sizes and/or types of powders.

A further drawback is represented by the fact that the intermediate turbulence chamber requires not easy filling modes, for example it must be manually supported during the powder insertion. Consequently, known cleaners often cannot ensure a precise dosage of the powder, nor prevent the dispersion thereof into the environment during the loading operation.

Summary of the invention

The technical problem posed and solved by the present invention is therefore that of providing a powder-cleaning device for dental use which allows overcoming one or more of the drawbacks mentioned above with reference to the prior art.

This problem is solved by a cleaning device according to claim 1 .

Preferred features of the present invention are the subject of the dependent claims.

The cleaning device of the invention mainly comprises a proximal arm for attachment to a source of compressed air, a distal arm for dispensing to the patient and an intermediate turbulence chamber, inside which an abrasive powder can be loaded. Advantageously, the device has a generally handpiece-shaped structure, so that it can be grasped by the operator performing the treatment at the proximal or distal arm.

According to a first aspect of the invention, the cleaning device has a controller of the air flow entering the turbulence chamber, arranged therefore upstream with respect to the mixing process.

In this way, it is possible to use different types of powder, in terms of mechanical properties and size of the granule, in the same device. In fact, the optimal mixing conditions can be obtained precisely by modifying the flow rate of the air entering the chamber and thus the fluid-dynamic parameters of the turbulence generated inside the chamber itself.

According to a second aspect of the invention, the turbulence chamber has a loading side door, which allows the powder to be inserted along an axis substantially orthogonal to the prevailing extension directions of the two arms.

In this way, the loading operation is extremely simplified and made more efficient, as the handpiece can be placed on a support plane and remain in a position suitable for loading without the need for support by an operator. Further advantages, features and methods of use of the present invention will be apparent from the following detailed description of some embodiments thereof, made by way of a non-limiting example. Brief description of the figures

Reference will be made to the figures of the accompanying drawings, in which:

^■ Figure 1A shows a side perspective view of a preferred embodiment of the powder- cleaning device according to the present invention;

^■ Figure 1 B shows a front view of the device in Figure 1 A;

■ Figure 1 C shows a rear view of the device in Figure 1 A;

^■ Figure 1 D shows a bottom view of the device in Figure 1 A;

^■ Figure 2A shows a longitudinal sectional view of the device in Figure 1A, in an open configuration of a respective control valve;

^■ Figure 2B shows an enlarged detail of Figure 2A;

■ Figure 3A shows a longitudinal sectional view of the device in Figure 1A, in a closed configuration of a respective control valve;

^■ Figure 3B shows an enlarged detail of Figure 3A;

^■ Figures 4A 4B refer to a preferred embodiment variant of the powder-cleaning device according to the present invention, showing each a partial longitudinal sectional view thereof, in an open and closed configuration, respectively, of a relative control valve.

The dimensions and curves shown in the figures above are to be understood as examples and are not necessarily shown in proportion. Detailed description of preferred embodiments

With reference initially to Figures 1A to 1 D, a powder-cleaning device according to a preferred embodiment of the invention is denoted as a whole with reference numeral 1 . The device 1 is intended for dental use, in particular for dental cleaning aimed at eliminating tartar or for other applications as mentioned above.

Device 1 mainly comprises:

- a first arm 2, which will be defined as proximal in relation to its proximity to the operator;

- a second arm 3 which will be defined as distal;

- a turbulence chamber 4, interposed between the proximal arm 2 and the distal arm 3 and internally in fluid communication with both. The aforesaid components are defined by an outer casing 100 of the device and by respective inner elements.

The proximal arm 2 is configured for attachment to a source of compressed air, in particular by means of a proximal connection 20 of a per se known type and based, for example, on a screw coupling. The proximal arm 2 has an oblong conformation and extends according to a first prevailing direction DP.

The distal arm 3 also has an oblong conformation and extends according to a second prevailing direction DD which, in the present example, is inclined, that is to say angled, with respect to the first direction DP.

The distal arm 3 has a distally end portion 30 shaped as a spout or dispensing nozzle and configured for dispensing a mixture of air and powder to a patient, according to modes that will be described hereinafter. Preferably, the end portion 30 is inclined with respect to the second prevailing extension direction DD.

In the present embodiment example, as will be explained below, a jet of water is also dispensed through the distal portion 30.

Device 1 is generally configured as a handpiece so as be grasped by an operator at the proximal 2 and/or at the distal arm 3.

The turbulence chamber 4, in this embodiment example, is defined by a lateral skirt 400, preferably with a cylindrical development, closed on both sides by a respective base or wall 41 , 42. In the present example, both bases 41 and 42 have a substantially circular profile seen in plan. One or both of these bases 41 , 42 may have a dome configuration. In the variant shown, the turbulence chamber 4 has a substantially cylindrical overall shape.

The turbulence chamber 4 has a loading side door 40 configured for insertion of the abrasive powder into the chamber itself. At the loading door 40, the chamber 4 can be closed by means of a port, or door 5, which is preferably removable.

According to the geometry shown, the loading door 40 and the corresponding door 5 substantially occupy the entire base 41 , which is therefore defined by the door 5 itself.

In the present example, the door 5 can be opened and closed by means of a screw coupling with the outer casing 100 in the part in which the latter laterally defines the turbulence chamber 4. In the example shown, therefore, the door 5 is rotatable according to an axis of rotation A. In particular, in the present embodiment, the door 5 is made in the form of a unscrewable ring.

The axis A is substantially orthogonal, or at least oblique, with respect to plane P defined by the prevailing development directions DP and DD of the arms 2 and 3. Such a plane P is substantially that of representation of the longitudinal sections of Figures 2A and 3A. The axis A also coincides, in the present example, also with a loading direction of the chamber 4, i.e. of access through the door 40.

In the present embodiment, by virtue of the configuration described, the turbulence chamber 4 can be loaded with the abrasive powder, through the door 40, placing the device 1 resting on the side opposite the door 40 itself, i.e. substantially at the second base or wall 42, and preferably also on arms 2 and 3. Other geometries are possible to obtain the same result, according to which the loading operations can be carried out easily, by a single operator who does not need to manually support the device 1 or to have a dedicated support tool.

Advantageously, the door 5 has a transparent window or portion 50 which allows the operator to view the amount of powder contained inside the chamber 4 and/or the turbulence conditions which are established therein and, in general, to check the local operation of the device 1. In the present example, this transparent window 50 occupies a prevailing area with respect to the plan extension of the door 5 and preferably has a circular profile or in any case corresponding to that of the door 5 itself.

According to a preferred embodiment, the door 5 has a peripheral gripping portion 51 , which in the present example is substantially circular ring in shape. The gripping portion 51 can have radial edges or projections 52 with substantially linear development to facilitate gripping and rotation.

The door 5, particularly when in the form of a ring, can be made of stainless steel.

In an application example, the turbulence chamber 4 can be sized for an internal working pressure equal to about 3 bar, with safety sizing at about 9 bar. The device 1 of the present embodiment also comprises a flow controller 10, configured to allow a variation of the air flow rate that enters the turbulence chamber 4. The controller 10 is arranged on the proximal arm 2 upstream of the turbulence chamber 4. Advantageously, the controller 10 allows a modulation of said flow rate between a condition of minimum air supply, which preferably corresponds to zero flow, and a condition of maximum air supply.

Figures 2A and 2B refer to a condition of maximum or near maximum flow rate, whereas Figures 3A and 3B to a minimum flow condition, which may be in particular null.

With reference to Figures 2A and 2B, the controller 10 is placed at an air feeding channel 21 , which passes through the proximal arm 2 to supply compressed air from the coupling 20 to an inlet of the turbulence chamber 4. In the present embodiment, the controller 10 comprises a plug or pin 1 1 . The latter has a head 1 1 1 and a stem 1 14.

The head 1 1 1 is provided with a shaped end surface 1 12, in particular with substantially arched profile and even more preferably with spherical geometry. A seal can be provided at the head 1 1 1 , in particular an O-ring 1 13, for example received in a seat formed in the head 1 1 1 itself.

The stem 1 14 defines a first oblong portion 1 15 adjacent the head 1 1 1 , an intermediate portion 1 16 of reduced cross section and an end portion 1 17. The transitions between the first portion 1 15 and the intermediate portion 1 16 and between the latter and the end portion 1 17 are defined by local tapered profiles.

The pin 1 1 is selectively translatable into a seat 21 1 of the proximal arm 2 according to a direction T substantially orthogonal to the direction DP and substantially lying on or parallel to the aforesaid plane P. The seat 21 1 has, in direction T, a first enlarged portion 212 within which the head 1 1 1 moves, and a second reduced portion 213 within which the stem 1 14 moves.

On the stem 1 14, in the part closest to the head 1 1 1 , an elastic return element 120 can be associated, in particular a helical spring. The latter is interposed between a abutment surface of the head 1 1 1 and a abutment surface of the seat 21 1 , the latter positioned at the transition between the two portions 212 and 213. The element 120 is configured to counteract the action of an actuation element 12 described below, by pushing the pin 1 1 into a raised position of greater projection from the seat 21 1 .

The pin 1 1 is actuated in translation by the above actuation element 12 which can be operated by the operator. In particular, the actuation element 12, in the present example, is made in the form of a ring which is rotatably coupled on the outer casing 100 of the device 1 . Again in the present example, the actuation element 12 rotates about an axis substantially corresponding to direction DP.

In the arrangement described, the actuation element 12 has a shaped guide surface 121 , in particular with a cam profile, which acts in abutment on the head 1 1 1 , in particular on the shaped surface 1 12 thereof.

By such a shape coupling, the pin 1 1 selectively slides into the seat 21 1 between a position of maximum air supply, or maximum flow, corresponding to Figures 2A and 2B, and a minimum supply position, shown in Figures 3A and 3B. In the maximum or nonzero position (Figure 2B), the intermediate portion 1 16 of the stem 1 14 is partially arranged within the enlarged seat 212, allowing the passage of air therethrough, within the reduced seat 213 and then in the portion downstream of channel 21 . In other words, the pin 1 1 is raised towards the outside of the device 1 so as to allow the flow of air coming from the coupling 20 to pass. In the minimum flow position (Figure 3B), the pin 1 1 is lowered towards the inside of the device 1 . In this position, the portion 1 15 inhibits the passage of air from the enlarged seat 212 within the reduced seat 213, occluding the feeding channel 21.

As said, intermediate positions are provided for reducing the air passage area between the lumen portions of the channel 21 upstream and downstream of the controller 10. The spring 120 ensures a continuous abutment between the two surfaces 1 12 and 121 , ensuring a return motion of the pin 1 1 in a raised position towards the outside of the device 1 .

Upstream and/or downstream of the pin 1 1 , non-return flow control means can be applied on the channel 21 , such as a valve 22 suitable for preventing backflow of air towards the coupling 20.

The device 1 also advantageously comprises means for dispensing a jet of water, in particular a channel 7 inside the two arms 2 and 3 and passing through a wall of the turbulence chamber 4. Channel 7 extends between a proximal end configured for attachment to a fluid source and a distal end, arranged at the end portion 30 of the distal arm 3.

In an embodiment variant, the compressed air feeding channel 21 may be made, at least locally, of deformable material, and the flow control obtained, for example, by means of an outer plug or pin which rests on the channel itself.

In use, the cleaning device 1 is connected to the dentist's chair or to a different power supply at the coupling 20 and possibly through a connector per se known.

As said, the turbulence chamber 4 is in fluid communication with both arms 2 and 3, so that the compressed air can be fed into the chamber through the proximal arm 2, with a flow rate managed by the controller 10.

As soon as the compressed air enters the chamber 4, it creates a turbulence which creates a mixture of air and powder which, being at a pressure greater than the ambient pressure, is directed towards the device outlet through the distal arm 3.

Varying the flow rate changes the turbulence inside the chamber 4, thus allowing the use of different types of powder.

Furthermore, the control of the air flow carried out upstream of the turbulence chamber allows the operator to modulate the amount of flow that reaches the patient, without the powder passing through a controlling means and thus avoiding any risk of infiltration or jamming. The water, as mentioned, is instead directed directly towards the outlet of the device 1 . The above handpiece cleaner may also be associated with a control unit selectively connectable thereto for determining, for example, the state thereof, optionally associated with local sensors.

Figures 4A and 4B refer to an embodiment variant of the device of the preceding figures, which will be described hereinafter solely in relation to the differences with what has already been described. In such Figures 4A and 4B, components similar to those already described are denoted with the same numeral reference.

The difference of this embodiment variant relates to the flow rate control modes.

In particular, also in this case the flow controller comprises a plug or pin 1 1 and an actuation element 12 such as those already described, which cooperate by means of a shape coupling.

In this variant, the stem of pin 1 1 carries, at the transition between the portions 1 15 and 1 16, a further sealing element, such as an O-ring 1 13'.

In the present variant, at the reduced portion 213 of the seat 21 1 , a hole or passage duct 6 is provided which allows the air coming from the feeding channel 21 to reach the downstream channel, herein denoted by 21 ', passing precisely through seat 213. This flow is added to that allowed through the passage slot of the enlarged seat 212, the slot herein denoted by 212' and already associated with the embodiment in Figures 2A-3B. In the open position in Figure 4A, the air arriving from the feeding channel 21 can pass through both the duct 6 and through the slot 212'. In the closed position in Figure 4B, the air can cross only the duct 6 and thus the seat portion 213.

Therefore, the provision of the duct 6 allows an additional possibility of control, or calibration, of the air flow.

Specific implementation methods may also allow an inhibition of passage through duct 6.

The present invention has been described thus far with reference to preferred embodiments thereof. It is understood that other embodiments may exist that relate to the same inventive scope, as defined by the scope of protection of the following claims.