FIELD OF THE INVENTION

The invention is in the field of oral care, and pertains to the generation and administration, into the oral cavity of a subject, of oral care antimicrobials. Particularly, the invention pertains to an integrated system for oral irrigation and administration of electrochemically activated solutions (EC AS).

BACKGROUND OF THE INVENTION

Dental plaque is a biofilm or mass of bacteria that grows on surfaces within the mouth. It is commonly found between the teeth and along the cervical margins. Dental plaque is also known as microbial plaque, oral biofilm, dental biofilm, dental plaque biofilm or bacterial plaque biofilm. While plaque is commonly associated with oral diseases such as caries and periodontal diseases (gum diseases), such as periodontitis and gingivitis, its formation is a normal process that cannot be prevented.

Dental plaque can give rise to dental caries (tooth decay) - the localised destruction of the tissues of the tooth by acid produced from the bacterial degradation of fermentable sugar - and periodontal problems such as gingivitis and periodontitis. Its progression and build up is what leads to oral problems, hence it is important to disrupt the mass of bacteria and remove it daily.

It is customary to control and remove plaque by means of tooth brushing and interdental aids such as dental floss or oral irrigators.

Removal of dental biofilm is important as it may become acidic causing demineralisation of the teeth (also known as caries), initiate inflammation in the gum, or harden into calculus (also known as tartar). Calculus cannot be removed through

toothbrushing or with interdental aids and can only be removed through professional cleaning. Therefore, removal of the dental biofilm will prevent the development of caries and gum diseases.

A persistent problem is that biofilm removal only addresses biofilm once it has grown on a surface. Methods have therefore been developed to reduce the number of live bacteria in the mouth, and particularly on dental surfaces and in interdental spaces. Reducing the number of live bacteria will increase the time before plaque accumulates.

One method to accomplish this is to administer into the oral cavity so-called electrochemically activated solutions (ECAS), sometimes also referred to as electrolysed water. These solutions are based on a process in which antimicrobials are generated by passing a current through a salt solution. Particularly, in such a process a current passes between, e.g., titanium or carbon electrodes to generate the reactive chlorine species hypochlorite (C10-) and hypochlorous acid (HCIO). These species are antimicrobial, and processes for generating them are well known.

It has been considered to generate ECAS and use it as a mouth rinse.

Reference is made to GB 1,484,878. This describes an apparatus adapted to generate a treatment liquid by electrochemically activating water. The apparatus includes a unit adapted to propel the treatment liquid into the oral cavity as a jet or a spray.

Generating and administering ECAS in the specific situation of applying it by means of an oral irrigator, however, comes with issues. It should be understood that ECAS generation is common in situations, such as disinfecting swimming pools, wherein no direct concern exists as to health effects of ECAS. In the event of administration into the mouth, however, a too high concentration of hypochlorite will be risky or painful to the subject. Also, in some jurisdictions limits apply to the concentrations to be administered to humans (e.g. in the US a regulation establishes 500 ppm as the maximum residual concentration of hypochlorite allowed in food). At the same time, it is not useful to generate and store ECAS in advance, since it is prone to degradation and will thus lose its activity.

It is thus desired to provide a system in which ECAS can be generated in direct connection with an applicator for an oral rinse (such as an oral irrigator), but wherein the ECAS concentration administered is well controlled. It will be understood that, in connection with an oral irrigator, the control mechanism should not require complex, or even separate, controls. Also, the control should not be dependent on manual action or process interpretation by the users of the applicator, who cannot normally be expected to safely act as chemical process operators. Rather, the control mechanism should be capable of being integrated into a hand-held device, and should be able to be operated automatically.

The device of GB 1,484,878 comprises an enclosure, e.g. a tube, provided with electrodes. In said enclosure, ECAS is generated in situ, and directly dispensed therefrom. Whilst this addresses the desire of avoiding the preparation of ECAS in advance, it necessarily limits any successful application of the device to methods in which the dispensing rate is sufficiently slow for EC AS to be generated prior to expulsion of liquid from the device. This problem needs to be addressed, and more particularly so in the event of modern oral irrigators, from which jets of relatively small amounts of liquid (possibly including air) are dispensed at relatively high jet velocities.

SUMMARY OF THE INVENTION

In order to better address the foregoing desires, the invention, in one aspect, provides an oral irrigator comprising a liquid container configured to hold a liquid; said container having an outlet for liquid that is in fluid communication with a liquid inlet of a mixing chamber; said mixing chamber having a gas inlet that is in fluid communication with a source of pressurized gas and having an outlet to a dispensing nozzle, whereby the mixing chamber is configured to transport a mixture of liquid and gas to the dispensing nozzle; said dispensing nozzle having an exit to an outside environment, and whereby the dispensing nozzle is configured to dispense said mixture of liquid and gas to said outside environment; wherein the oral irrigator comprises an electrolysis chamber configured to electrochemically treat a passing liquid, said electrolysis chamber comprising a pair of electrodes connected to a power source, wherein the electrolysis chamber is positioned downstream of the liquid container, and in fluid communication therewith, and upstream of the outlet of the mixing chamber, and in fluid communication therewith, wherein fluid communication from the mixing chamber to the exit of the dispensing nozzle is controllable independently of the fluid communication from the liquid container to the electrolysis chamber, and wherein the components of the oral irrigator are all contained in or on a housing that is adapted to be capable of being normally lifted and held by a human.

In another aspect, the invention presents a method for interdental cleaning, the method comprising providing an aqueous solution of sodium chloride, subjecting said solution to electrolysis so as to produce an aqueous hypochlorite/hypochlorous acid solution, and dispensing said hypochlorite/hypochlorous acid solution into the oral cavity, wherein the electrolysis and the dispensing are conducted by means of an oral irrigator as described in the preceding paragraph.

In a still further aspect, the invention provides an oral irrigation fluid comprising water, sodium hypochlorite, and carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic drawing of an oral irrigator in accordance with the invention.

Fig. 2 presents a scheme for a control arrangement of ECAS generation in accordance with an embodiment of the invention.

Fig. 3 presents a scheme for a control arrangement of ECAS generation in accordance with another embodiment of the invention.

Fig. 4 compares process schemes for an oral irrigator as it currently exists (A) and one with ECAS generation added in accordance with an embodiment of the invention (B).

DETAILED DESCRIPTION OF THE EMBODIMENTS

In a general sense, the invention is based on the judicious insight to combine the in situ generation of ECAS with controlling the actual dispensing of the ECAS through a mixing chamber.

The term "ECAS" refers to any electrochemically activated solution. More particularly, the ECAS is an electrochemically activated solution of sodium chloride. Any source of chloride anion could be used for this reaction, but sodium chloride is used here as an example. As a result of the electrochemical activation, the solution (hereinbefore and hereinafter also referred to as the "hypochlorite/hypochlorous acid solution" ) comprises a mixture of hypochlorite anions and hypochlorous acid (i.e., a mixture of oxidised chloride ions, with the ratio depending on the surrounding pH of the medium). As customary in the art, ECAS can also be referred to as "electrolysed water." The concentration of sodium chloride prior to electrolysis generally is in a range of from 0.05% to 35.9% (w/v), such as from 0.1% to 10%, preferably from 0.1% to 0.9% (w/v). Apart from sodium chloride solutions, also other salt solutions can be electrochemically activated. Examples hereof include potassium chloride, calcium chloride.

The term "fluid communication" refers to any connection between a first unit, or a first part of a device, and a second unit, or a second part of a device, via which fluids, including liquids and gases, can flow. Such flow can be direct or indirect. Direct flow can be, e.g., through a fluid communication channel such as a pipe, a tube, a hose, or a flow line, said communication channels possibly comprising one or more valves or other units that serve to open or close the communication channel, or that adjust the size of an opening or closure in said communication channel. Indirect flow can be, e.g., via one or more treatment units, pressure-reducing or increasing units, or other units in which the fluid is subjected to a treatment (such as a chemical reaction or a physical treatment such as mixing or standing). Generally, such units have an inlet for the fluid to enter and an outlet for the fluid to exit.

The fluid communication can be controllable fluid communication. In that event, the direct or indirect flow can be interrupted or adjusted (such as in terms of the absolute amount of liquid, the flow rate, or both). Such interruption or adjustment can be controlled manually, automated, or made dependent on related events, such as feedback information resulting from operating one part of a device, that is sent to a processor adapted to control fluid communication.

The terms "upstream" and "downstream" are used such as to be related the normal operation of an oral irrigator. Accordingly, the downstream side of the oral irrigator is the exit (such as the exit of a dispensing nozzle) through which an irrigation fluid can be applied to the oral cavity. The units and communication channels that, in the normal operation of the oral irrigator, precede the actual exiting of the irrigation fluid, are thus positioned upstream of the exit.

The oral irrigator of the invention serves to dispense, through a jet or a spray, a mixture of liquid and gas. To this end the device comprises a mixing chamber. The mixing chamber has a gas inlet that is in fluid communication with a source of pressurized gas. The source of pressurized gas can be a container (such as a gas canister) adapted to hold pressurized gas. In that event, such container has a gas outlet that is in fluid communication with a gas inlet of the mixing chamber. Suitable gases are, e.g., carbon dioxide, nitrogen, or pressurized air. Particularly, such gases can be of medical grade.

In an interesting embodiment, the source of pressurized gas refers to a compression unit, such as a pump configured to forward pressurized gas into the mixing chamber. In an embodiment thereof, the pump is adapted to draw gas, particularly air, from an outside environment into a gas inlet of the oral irrigator, prior to pressing same into the mixing chamber. Thereby the pump preferably is a reciprocating pump, such as a plunger pump or a piston pump. E.g., the pump comprises a motor adapted to suck air into said gas inlet, whereby the gas inlet is in fluid communication with a piston. The piston is generally contained in a piston chamber configured to allow backward and forward movement of the piston (typically a cylinder).

Typically, thereby air will be drawn into both the piston chamber and the mixing chamber. However, a provision can also be made to close off the mixing chamber from the air inlet, and allow an inlet into the mixing chamber to be opened upon release of the piston.

The piston is able to be released from a locked position, such that, upon release, it will press the air into the mixing chamber. The release of the piston typically follows after a desired amount of air has been drawn into the piston chamber, and desirably compressed. It will be understood that drawing air into the piston will typically refer to drawing air into a chamber, such as a cylinder, that on one end (e.g., a longitudinal end, such as the bottom of the chamber) is closed off by the piston, and on an opposite end (e.g. the opposite longitudinal end, such as the top of the chamber) is in fluid communication with the mixing chamber, or is in fluid communication with the mixing chamber upon release of the piston. The piston can be released by various mechanisms. E.g., manually or as a result of a desired, e.g. predetermined, amount of air having been let in. Appropriate releasable fixations for a piston are known to the skilled person, such as a lock that can be pushed or drawn away, a spring underneath the piston that exerts a releasing action dependent on the amount of air drawn onto the piston, or other triggers available in the art.

Compression units, e.g. microcompressors, suitable for being included in oral irrigators, particularly hand-held type oral irrigators, are well available to the skilled person. Without being limitative, reference can be made to background descriptions in WO 02/1372, US 2010/35200, WO2015/173691.

Without wishing to be bound by theory, the inventors believe that the invention strikes a balance between the need to generate ECAS in situ, so as to prevent untimely degradation of ECAS, and a sufficient residence time of a salt solution in an electrolysis chamber to generate a desirable amount of ECAS.

To this end, the fluid communication from the mixing chamber to the exit of the dispensing nozzle is controllable independently of the fluid communication from the liquid container to the electrolysis chamber. As a result, the residence time of the salt solution during electrolysis in the electrolysis chamber can be adjusted. This presents an advantage as compared to the device described in GB 1,484,878. Therein, the ECAS generation is limited to electrolysis of a salt solution during or immediately before the time that such solution is being dispensed, i.e. in passing towards the exit of the dispensing nozzle.

In an interesting embodiment of the oral irrigator of the invention, the electrolysis chamber is positioned upstream of the mixing chamber, and in controllable fluid communication therewith. This facilitates the aforementioned possibility to adjust the residence time of liquid (such as a salt solution) in the electrolysis chamber. Also, an advantage is that an oral irrigation fluid can be dispensed from the mixing chamber irrespective of whether or not an amount of ECAS is included. In addition to the latter, any desired flexibility of dispensing fluids with or without ECAS can be further increased by the addition of one or more further liquid containers. Such further liquid containers can be adapted to hold water and/or solutions or dispersions comprising oral care agents other than ECAS.

In another interesting embodiment, the mixing chamber comprises the electrolysis chamber. Particularly, the electrolysis chamber and the mixing chamber thereby coincide. In this embodiment, the electrolysis effectively takes place in the mixing chamber. This has an advantage in that the oral irrigator of the invention can be just as compact as a conventional oral irrigator without an electrolysis chamber. Another advantage is that the setting of the residence time of liquid in the electrolysis chamber and the frequency of dispensing oral irrigation fluid require a single setting only, which simplifies the operation of the device by the end-user. In this embodiment it is preferred for the electrodes to be provided each on a wall of the mixing chamber, so as to provide a physically undisturbed mixing environment.

It will be understood that various other embodiments are possible. E.g., in the embodiment in which the electrolysis is conducted in the mixing chamber, the device of the invention can comprise one or more additional liquid containers adapted to supply the mixing chamber with other liquids. Or, e.g., in the embodiment in which the electrolysis chamber is positioned upstream of the mixing chamber, it will be possible to include such control electronics in the device, that the electrolysis, the mixing, and the dispensing are adapted relative to each other such as to present a single, optimal setting to the end-user. Also, in any of the embodiments, it is conceivable to include such controls that the electrolysis can be set "on" or "off." This can be either through manual operation, or via a pre-programmed choice of settings.

Preferably, the release, into the mixing chamber, of pressurized gas, also serves to control the fluid communication from the mixing chamber to the exit of the dispensing nozzle. I.e., the mixing chamber and the dispensing nozzle are designed such that liquid contained in the mixing chamber is not dispensed, unless and until pressurized gas is made to enter the mixing chamber, and to exit the dispensing nozzle. This does not exclude that, in some embodiments, the air inlet itself is in fluid communication with the mixing chamber. As a result of encountering the pressurized gas, the liquid in the mixing chamber will mostly break up into a plurality of droplets. Some of the liquid will thereby remain in a stream form, and some of the gas will remain in a streaming form, all furthered into the dispensing nozzle, and forced (as a result of the gas pressure) through the exit thereof.

As mentioned above, a challenge in providing ECAS specifically for oral care, is to control the ECAS concentration dispensed into the oral cavity. The oral irrigator of the invention allows the implementation of a system to this end. Thereby, the device of the invention comprises a flow rate adjuster adapted to adjust the flow rate of liquid from the liquid container into the electrolysis chamber. A flow rate adjuster can be, e.g., a valve through which the amount of liquid per unit of time entering the electrolysis chamber can be set, e.g., by adjusting the size of an aperture through which the liquid enters said chamber. Also other flow rate adjusters are conceivable, e.g. the addition of a circular fluid

communication loop provided with an adjustable pump, via which the flow rate of the liquid can be set directly.

The foregoing can be operated manually, whereby the end-user can learn to adjust the flow rate to personal needs. Preferably, a pre-arranged setting avoids the generation of unallowable high concentrations of ECAS. Preferably, however, the flow rate adjuster is applied in conjunction with one or more sensors that measure the input into the electrolysis chamber, the output from the electrolysis chamber, or both. Accordingly, it is preferred for the oral irrigator of the invention to comprise a hypochlorite sensor downstream of the electrolysis chamber. Said sensor thus measures the output of the electrolysis chamber, i.e., providing a direct indication of whether the ECAS concentration prior to dispensing is too low or too high. The hypochlorite sensor, which itself can be provided by the skilled person as available in the art, is particularly adapted to send feedback to a processor that, in turn, is adapted to control the flow rate adjuster. Non- limiting examples of hypochlorite sensors include amperometric sensors, such as provided by Dosatronic, e.g., DOSASens type DCL10, Chlorine Sensor Type CP 2.1, Chlorine Sensor Type CS 2.3, or the FCLTX-100 series from Omega. Also beyond these specific examples, hypochlorite sensors can be provided without further research.

In an alternative, but preferably combined with a hypochlorite sensor in the same device, the oral irrigator of the invention comprises a salinity sensor upstream of the flow rate adjuster, This sensor too, is adapted to send feedback to a processor adapted to control the flow rate adjuster. Also a salinity sensor, which measures salt concentration, can be provided as available in the art. Suitable examples can be found in existing technology using conductance measurements, similar to pool chlorination measurements.

The electrolysis chamber itself can be designed in a known way. Generally two electrodes are present, connected to a power source so as to provide an anode and a cathode. The electrodes can, each independently, be made of any suitable material, such as iron, carbon, platinum or any other electrical conductor material. In the invention it is preferred to use carbon or titanium, or a combination of each. Electrodes can suitably be coated, e.g. to improve lifespan. Examples of coatings include mixed metal oxide (MMO) coatings containing various components e.g. iridium, ruthenium, platinum, zirconium, niobium, tantalum. Preferably, the electrodes are plate electrodes. These can be flat plates, extending into the electrolysis chamber or put against the walls thereof. Particularly in the latter case, the electrodes can be curved, e.g., following the shape of the wall of an electrolysis chamber provided in a handheld oral irrigator.

The power source can be obtained from an AC connection, such as a standard domestic power supply, typically employing an adapter so as to convert domestic AC power to DC power. The power source preferably is a battery, or a set of batteries, preferably placed in a corresponding compartment of the oral irrigator. The batteries can be replaceable and/or rechargeable, as is customary in the art, particularly for handheld oral irrigators. In one embodiment, the device of the invention comprises a battery compartment having a conductive connection to the electrode system. In another embodiment, the device comprises both an adapter for a domestic AC outlet, and a battery compartment, both of which having a conductive connection to the electrode system.

An oral irrigator, such as an interdental cleaner, typically comprises a source of liquid; a system for moving a selected amount of liquid from the source thereof into a liquid pathway; a driving unit such as a pump or a source of pressurized gas, or a

combination thereof; and a control arrangement for releasing a selected amount of gas into contact with the liquid, resulting in liquid being propelled out of a nozzle portion of the cleaner. Suitable devices are described, inter alia, in WO 2010/055433, WO 2010/055434, WO 2008/012707, WO 2014/068431. Typically preferred jet velocities are of the order of 5 m/s to 50 m/s, such as 10 m/s to 40 m/s, such as 20 m/s to 30m/s. The pumping unit or units can be separate compressors, the pumping function can be provided by the pressurized gas, or both. Preferably, the oral irrigator comprises a microburst pump.

The oral irrigator of the invention is fully hand-held, wherein the components of the oral irrigator as described above are all contained in or on a housing that is adapted (taking into account size, shape, and weight) to be capable of being normally lifted and held by a human, preferably in a single hand.

However, another type of oral irrigator different from the one of the inveniton, can include a system in which part of the components can be hand-held, and part of the components can be comprised in or on a basis or docking station. The invention also pertains to a method for interdental cleaning. The method comprises providing an aqueous solution of sodium chloride, subjecting said solution to electrolysis so as to produce an aqueous hypochlorite solution, and dispensing said hypochlorite solution into the oral cavity, wherein the electrolysis and the dispensing are conducted by means of an oral irrigator as described hereinbefore, in all if its embodiments.

The oral irrigator of the invention dispenses an oral irrigation fluid comprising a mixture of liquid and gas, particularly pressurized air. Hitherto, in the art, such a fluid has not been provided in conjunction with EC AS. In this respect the invention also pertains to an oral irrigation fluid comprising water, sodium hypochlorite, and air.

The invention will further be illustrated with reference to the non- limiting figures discussed hereinafter.

Fig. 1 is a schematic drawing of an oral irrigator (1) in accordance with the invention. Herein the following components are shown:

(2) A pump configured to forward pressurized air ;

(3) Communication channels (tubes) for fluid;

(4) A valve;

(5) A pressure chamber (mixing chamber);

(6) A nozzle for dispensing oral irrigation fluid into the oral cavity, particularly of a human;

(7) An electrolysis chamber (ECAS cell);

(8) A feeding pump for liquid to be subjected to electrolysis;

(9) Control electronics;

(10) Data connections for transferring information;

Fig. 2 presents a scheme for a control arrangement of ECAS generation in accordance with another embodiment of the invention. Herein the uninterrupted lines indicate flow of liquid, the broken lines indicate flow of information. Liquid to be electrolysed (a) flows to an electrolysis chamber (7) via a salinity sensor (11) and via a flow rate adjuster (12), positioned downstream of the salinity sensor, and upstream of the electrolysis chamber. Information (b) obtained from the salinity sensor is processed in a processor (13); processed information (c) from the processor is sent to the flow rate adjuster, so as to adjust the flow rate of liquid to be electrolysed, depending on the processed data related to salinity input.

Fig. 3 presents a scheme for a control arrangement of ECAS generation in accordance with another embodiment of the invention. Herein the uninterrupted lines indicate flow of liquid, the broken lines indicate flow of information. Liquid to be electrolysed (a) flows to an electrolysis chamber (7) via a salinity sensor (11) and via a flow rate adjuster (12), positioned downstream of the salinity sensor, and upstream of the electrolysis chamber. Electrolysed liquid (d) passes through a hypochlorite sensor (14) before being dispensed. Information (b) obtained from the salinity sensor is processed in a processor (13);

Information (e) obtained from the hypochlorite sensor is also processed in the processor, thus providing a feedback loop in relation to the amount of ECAS generated. Information (c) from the processor is sent to the flow rate adjuster, so as to adjust the flow rate of liquid to be electrolysed depending on the processed data related to salinity input and hypochlorite output.

Fig. 4 compares process schemes for (A) a currently existing oral irrigator and (B) the invention, with ECAS generation added. In the current device (A), water is pumped from the reservoir into the mixing chamber first (item (a) in the scheme). A motor controlling an air piston then starts, which retracts it against a spring, sucking air into the system (into the piston and mixing chambers). Once the spring reaches a trigger it releases, which pushes the air and water out of the mixing chamber into the nozzle, creating a microburst (items (b) and (c) in the scheme). For the invention, in scheme B, an extra step is indicated in which a separate reactor is added upstream of the mixing chamber. The reactor is activated as water (saline) is pumped from the reservoir into the mixing chamber. After that point, the process of creating the microburst is the same as in the conventional scheme (A). In an alternative embodiment, the ECAS reactor is added into the body of the mixing chamber.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

For example, it is possible to operate the invention in an embodiment wherein only a hypochlorite sensor is present (downstream of the electrolysis chamber), and not a salinity sensor.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain features of the invention are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

In sum, we hereby disclose a set-up for an oral irrigator, as a system of components and as a single, hand-held device. Herein a provision is made to dispense oral irrigation fluid comprising antimicrobial ions produced in situ (in the system or device) by electrolysis of an appropriate salt solution, i.e., an electrochemically activated solution (ECAS). The production of EC AS is enabled by providing an electrolysis chamber. The oral irrigator is of the type wherein oral irrigation fluid to be dispensed is mixed with pressurized gas in a mixing chamber, upstream of a dispensing nozzle. The electrolysis chamber is comprised in the mixing chamber, or upstream thereof. In accordance with the invention, the amount of ECAS can be controlled by means of a salinity sensor, a hypochlorite sensor, or both.