Subgingival cleaning

Abstract

A subgingival cleaning system 10 for cleaning a subgingival area, such as a periodontal pocket, is disclosed. The system includes a liquid flow source 60 for generating a liquid flow and a gas flow source 70 for generating a gas flow. Each of the liquid flow source and the gas flow source is coupled to a nozzle arrangement 40 configured to be directed toward the subgingival area to be cleaned. The nozzle arrangement includes at least one nozzle 41, 42, 43. The system is configured to generate a liquid stream from the liquid flow source, the liquid stream including a series of liquid pulses. Each of the liquid pulses has a duration of 5 to 100 ms, preferably 8 to 40 ms, with an interval between subsequent liquid pulses of 1 to 50 ms, preferably 2 to 10 ms. A gas flow from the gas flow source at least partially fills the interval. A nozzle arrangement for forming such a subgingival cleaning system is also disclosed.

Description

Technical Field

[0001] The present invention relates to a subgingival cleaning system including a liquid flow source coupled to a nozzle configuration configured to be directed towards a subgingival region to be cleaned, the nozzle configuration including at least one nozzle.

[0002] The present invention further relates to a nozzle configuration for cleaning such a subgingival region.

Background Art

[0003] Periodontitis is a highly prevalent gum infection worldwide. For example, in the United States, approximately half (46%) of adults over 30 years old are diagnosed with periodontitis, raising public health concerns. Periodontitis is irreversible due to the destruction of the tissues that support the teeth, which do not fully repair. This results in the gums detaching from the teeth and a gap forming between the tooth surface and the gums. This gap is called a periodontal pocket, which forms a niche suitable for the growth of certain bacterial species and can lead to loosening or loss of teeth as periodontal disease progresses.

[0004] Following the large population of patients diagnosed with periodontitis, there is another large population suffering from periodontitis or incipient pocket formation without being noticed by the patients or specialists. For these patients, additional oral hygiene is very important to prevent further progression and deepening of the pockets, which can ultimately lead to severe periodontitis.

[0005] The golden rule for the treatment of periodontitis is scaling and root planning by experts. This treatment relies on the experienced hands of dentists to remove calculus and biofilm on the surfaces of teeth and roots. To succeed in the treatment, patients are enrolled in maintenance therapy where they return to experts for cleaning every 3 to 4 months. Research shows that the compliance rate of patients who schedule a 1-hour appointment for 5 to 14 years of maintenance treatment is low (16%). Fear of dentists, economic factors, and the behavior of dentists have been cited as reasons for the low compliance rate. Therefore, there is a high need for home cleaning devices as a maintenance therapy for pocket cleaning. Additionally, such home cleaning devices can be ideally used to prevent the progression of early pockets even before specialized treatments such as scaling and root planning are required.

[0006] The targets for subgingival cleaning can be divided into multiple sections.

[0007] - Subgingival calculus adhering to the root. This can only be removed by experts.

[0008] - Multilayered subgingival plaque. a) Basal layer: Adheres directly to the surface of the root. This layer mainly contains bacteria not related to periodontal disease (benign commensal bacteria). This layer generally shows high adhesiveness. b) Intermediate layer containing mainly filamentous or rod-shaped cells. This layer (sometimes called the orange complex) is related to gingivitis and shows intermediate adhesiveness. c) Uppermost layer. This mainly contains filamentous, rod-shaped, or coccus-type cells. This layer (sometimes called the red complex) is related to periodontitis, is soft, and has low adhesiveness. d) An additional loose bacterial layer covering the attached biofilm has been reported from several sources, and these are species strongly related to periodontitis.

[0009] - Subgingival fluid: Gingival crevicular fluid (GCF) is formed in the subgingival space and inside the pocket, and its formation rate increases as inflammation and pocket depth increase. Bacterial toxins and other bacterial by-products may accumulate in GCF.

Summary of the Invention

Problems to be Solved by the Invention

[0010] Combined with occasional professional calculus removal and removal of the strong basal layer, the hypothesis holds that it is sufficient for a household cleaning device to remove the soft top layer where most of the toxin-containing liquid and strong periodontal pathogens lurk. Since the growth of periodontal pathogens is slow and usually takes 2 to 3 days to return to normal, cleaning once a day or every other day is sufficient. However, in order to succeed in cleaning management, the entire depth of the pocket needs to be cleaned of pathogens in order to prevent the process of gingival detachment occurring at the edge of the pocket. Reaching deep is one of the important issues for successful cleaning technology.

[0011] An example of such a household cleaning device is disclosed in US2020 / 276003A1, which discloses an oral irrigator including a reservoir, a tip fluidly connected to the reservoir, a motor with a drive shaft, and a pump. In use, a water jet passing through the tip is generated by the pump and directed by the user into the interdental space for subgingival cleaning such as subgingival periodontal pockets.

[0012] However, it has been found that such an oral irrigator is ineffective for periodontal pocket cleaning even when using a special subgingival cleaning tip. For example, in the case of moderately periodontitis patients, who are the most common among periodontitis patients, the deepest pocket is defined as 5 mm in depth. An oral irrigator using a water jet cannot clean to the full depth of such a periodontal pocket, especially when used at an inappropriate irradiation angle, and it has been found that the effect of the cleaning process performed by such an oral irrigator is limited. Correct aiming improves the effectiveness of the cleaning process of such an oral irrigator, but different subgingival regions, such as the buccal and lingual regions, require different optimal aiming angles, which may be difficult for the user to achieve. Additionally, effective cleaning of such relatively deep periodontal pockets requires 750 ml of water and 140 seconds of treatment time, which is not satisfactory from the user's perspective and may reduce the user compliance rate of the required cleaning management.

[0013] WO2013 / 001520 discloses an oral hygiene device that can be controlled to supply either a jet of air or a jet of air and liquid. This has been found to assist in the removal of residual food and dental plaque.

Means for Solving the Problems

[0014] The present invention aims to provide a subgingival cleaning system capable of achieving more effective periodontal pocket cleaning. The present invention further aims to provide a nozzle configuration for more effective periodontal pocket cleaning. The present invention is defined by the independent claims. The dependent claims define advantageous embodiments.

[0015] According to one aspect, there is provided a subgingival cleaning system in which a liquid flow source and a gas flow source are each fluidly coupled to a nozzle configuration disposed towards the subgingival region to be cleaned, the nozzle configuration including at least one nozzle, the liquid flow source being configured to generate a liquid flow having a series of liquid pulses through the nozzle configuration, the gas flow source being configured to generate a gas flow through the nozzle configuration, such that each liquid pulse is followed by the gas flow.

[0016] The present invention is based on the finding obtained from a simulation that the liquid injection speed in the periodontal pocket rapidly decreases as the pocket depth increases, due to the fact that the liquid jet has to penetrate a liquid column, for example a column 5 mm high, in the periodontal pocket of a patient suffering from moderate periodontitis. This fact causes a loss of momentum due to surface drag by the tooth wall and the liquid column, thereby reducing the speed of the liquid. Removing the liquid column from the periodontal pocket by gas between liquid pulses ensures that newly arriving liquid pulses penetrate to the deeper part of the periodontal pocket at an increased speed, while the pulsed nature of the liquid stream requires less liquid volume. As a result, a subgingival cleaning device is provided that provides improved cleaning of the periodontal pocket with less water volume and in a shorter time compared to a water irrigation cleaning device.

[0017] To achieve such more efficient cleaning performance, the liquid pulses each have a duration of 5 to 100 ms, preferably 8 to 40 ms, and the intervals between the liquid pulses each have a duration of 1 to 50 ms, preferably 2 to 10 ms. The liquid pulses are preferably generated at a cycle frequency of 20 to 100 Hz. If the duration of each liquid pulse is less than 5 ms, effective cleaning of the subgingival area may be impaired. On the other hand, if the duration of each liquid pulse exceeds 100 ms, the cleaning process performed by the subgingival cleaning system may require too much time and / or may use a significant amount of liquid. Similarly, if gas is provided to the subgingival area being cleaned during an interval less than 1 ms between liquid pulses, effective removal of the liquid column from the subgingival area being cleaned may not be achieved. On the other hand, if gas is provided to the subgingival area being cleaned for 50 ms or more, the cleaning process performed by the subgingival cleaning system may require too much time. Limiting the duration of each liquid pulse to 8 to 40 ms and the duration of each interval during which a gas flow is directed to the subgingival area being cleaned to 2 to 10 ms provides a particularly optimal performance window for the subgingival cleaning system.

[0018] In a preferred embodiment, to facilitate a particularly simple implementation of the subgingival cleaning system, the liquid is water and / or the gas is air. When referring to water, this can also mean an aqueous cleaning agent, such as a mouthwash, etc.

[0019] In one embodiment, the nozzle configuration has a single nozzle. The liquid flow source and the gas flow source are optional and are fluidly coupled to the single nozzle via a switch that switches the liquid flow and the gas flow. In this embodiment, both the liquid stream and the gas stream are alternating pulsed streams that pass through the same nozzle when supplied to the subgingival area to be cleaned. This is a relatively low-cost implementation of the nozzle configuration, but it presents a trade-off in that when switching from the liquid stream to the gas stream, it is necessary to remove the liquid remaining in the nozzle with gas. As a result, due to the fact that the supply of the full air pulse pressure may be delayed by the initial removal of the liquid from the nozzle, the effective removal of the liquid column in the periodontal pocket may require more time. Such switching of the liquid stream and the gas stream can be achieved using a switch or, alternatively, by inserting the gas stream into the pulsed liquid stream upstream of the single nozzle orifice.

[0020] In an alternative embodiment, the nozzle configuration has a first nozzle fluidly coupled to the liquid flow source and a second nozzle fluidly coupled to the gas flow source. This has the advantage that the gas flow can be supplied to the subgingival area for cleaning without the delay caused by removing residual water from the nozzle through which the gas flow passes. This further reduces the cycle time required for effective cleaning of the subgingival area.

[0021] The nozzle configuration can have a concentric nozzle configuration in which one of the first nozzle and the second nozzle surrounds the other, for example, the second nozzle may surround the first nozzle. This provides a particularly compact nozzle design where both nozzles are aligned to target the subgingival area to be cleaned. Alternatively, the first nozzle and the second nozzle can be spatially separated from each other and, for example, target this area from opposite directions to ensure effective cleaning of the subgingival area to be cleaned.

[0022] The gas flow from the gas flow source can have a plurality of gas pulses, each gas pulse at least partially following one of the liquid pulses, for example, each having the duration of the interval between the liquid pulses, or alternatively, the gas flow from the gas flow source may be a continuous gas stream. In the case of a continuous gas stream, the gas pressure is kept low enough, for example, at most 0.1 bar, to prevent the liquid pulse from breaking up into droplets.

[0023] In certain embodiments, the liquid flow source has a liquid reservoir fluidly coupled to the nozzle configuration via a fluid connection including a liquid pump. As a result, the liquid pulse can be generated by operating the liquid pump for a defined time period, for example, for the duration of the generated liquid pulse.

[0024] Preferably, the generated liquid pulse closely resembles a square wave in the sense that the liquid pulse tails off rapidly. This is because it improves the cleaning efficiency of the liquid pulse. In one embodiment, the low-pressure tail of the liquid pulse is avoided by the non-expandable nature of the fluid connection, liquid reservoir, and nozzle configuration. Thus, by preventing volume changes in the positive pressure system during liquid pulse generation, the non-expandable positive pressure system for the liquid promotes a rapid drop in liquid pressure at the end of liquid pulse generation. Alternatively or additionally, the fluid connection between the liquid flow source and the nozzle configuration has an active stop under the control of a controller that terminates the liquid stream from the liquid flow source to the nozzle configuration to achieve a sharp cut-off of the liquid pulse. Such an active stop can take the form of a valve such as a block valve or pressure relief valve, or a piston such as a pull-back piston that sucks the liquid out of the nozzle configuration.

[0025] Gas flows can be generated in various ways. In one embodiment, the gas flow source has an air piston within a nozzle configuration, and the air piston is driven by a liquid pressure generated by a liquid flow source that causes the air piston to draw air into the nozzle configuration. This is a particularly cost-effective solution in embodiments where the gas stream is pulsed. This is because in such a configuration, a gas pulse can be generated ahead of the liquid pulse as the liquid pulse moves towards the nozzle configuration.

[0026] Alternatively, the gas flow source has a gas pump or a gas canister, which is useful, for example, in embodiments where the gas stream is continuous. However, such a gas pump or gas canister can also be equally used to generate a pulsed gas flow.

[0027] In one embodiment, the gas pump is integrated with the nozzle configuration, which has the advantage that the gas pump can be fixed to such a system by attaching the nozzle configuration to an existing subgingival cleaning system.

[0028] According to another aspect, a nozzle configuration for a subgingival cleaning system configured to generate a stream of liquid pulses is provided. The nozzle configuration has a conduit for receiving the liquid pulses and a compartment including an air inlet valve and a pressure relief valve, each of the conduit and the compartment ending at an orifice of the nozzle configuration, and the compartment having a pressurizing configuration responsive to the liquid pressure generated by the liquid pulses for pressurizing the air within the compartment to generate a stream of air pulses through the pressure relief valve, each air pulse at least partially following one of the liquid pulses. Such a nozzle configuration can be employed in existing subgingival cleaning systems that generate liquid pulses to improve the cleaning performance of such systems by generating air pulses in addition to the liquid pulses. This air pulse can remove the water column from the subgingival region being cleaned, as described above.

[0029] A method for cleaning the subgingival area can also be provided. Such a method involves directing the fluid stream towards the subgingival area, where the fluid stream includes a series of liquid pulses, and a gas stream follows each liquid pulse. The gas stream has a plurality of gas pulses, for example, each having a duration corresponding to the interval between subsequent liquid pulses or being a continuous gas stream. Such a cleaning method has been found to effectively remove contaminants from the subgingival area, which is prone to causing periodontitis. As a result, regularly using this method, for example, daily or every other day, can contribute to the control of periodontitis in patients.

Brief Description of the Drawings

[0030]

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DETAILED DESCRIPTION OF THE INVENTION

[0031] Embodiments of the present invention will be described in more detail with reference to the accompanying drawings and by way of non-limiting examples.

[0032] It should be understood that the figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numbers are used throughout the figures to indicate the same or similar parts.

[0033] FIG. 1 schematically shows a subgingival cleaning system 10 according to an embodiment of the present invention. The subgingival cleaning system 10 has a base unit 20 and a handheld unit 30 fluidly connected to the base unit 20 via a tube 25. The base unit 20 can have a user interface 22, such as a dial or knob, by which a user can select an operating mode of the subgingival cleaning system 10. The handheld unit 30 has a nozzle configuration 40 with one or more nozzles for the user to direct a fluid stream at the subgingival area to be cleaned. The handheld unit 30 may include a switch 32 for activating / deactivating such a fluid stream. According to the present invention, the subgingival cleaning system 10 has an operating mode (which may be its only operating mode or one of a plurality of operating modes) in which a fluid stream is generated via the nozzle configuration 40. The liquid stream has a plurality of liquid pulses separated by gas. The gas can be a continuous gas stream or a pulsed gas stream such that the fluid stream passing through the nozzle configuration 40 consists of a sequence of liquid pulses sandwiched by gas pulses. In an alternative embodiment, the base unit 20 is omitted as a separate entity and its functions may be integrated into the handheld unit 30.

[0034] Upper plaque layer, attached biofilm, and subgingival fluid: Gingival crevicular fluid. It has been found that dirt within a periodontal pocket having a depth of 5 mm or more that causes periodontal disease, such as a layer of bacteria that is looser and covers the gingival crevicular fluid, can be removed more effectively by a gas, such as a gas pulse or such a liquid pulse separated by a continuous gas stream, compared to a continuous liquid stream. As explained above, this can be understood by removing the accumulated liquid from the periodontal pocket with air. This reduces the resistance and provides improved access of subsequent liquid pulses to the deep regions of such periodontal pockets. Particularly effective cleaning of the periodontal pocket is achieved when the liquid pulse has a duration in the range of 5 to 100 ms, preferably 8 to 40 ms (milliseconds), is temporally separated by an interval having a duration in the range of 1 to 50 ms, preferably 2 to 10 ms, and preferably gives a cycle frequency in the range of 20 to 100 Hz to the liquid stream. As will be readily understood by those skilled in the art, when the gas stream is a pulsed gas stream, the duration of each interval defines the duration of the gas pulse. In a preferred embodiment, such an interval, for example, the duration of the gas pulse, is in the range of 2 to 4 ms. The effects and advantages of such a pulsed fluid stream on the cleaning of the periodontal pocket will be demonstrated in more detail below. In an embodiment of the present invention, the liquid can be water and the gas can be air, although alternatives are envisioned. For example, the liquid may be an aqueous cleaning solution, water, or other suitable liquid. Here, the gas may be provided from a gas canister or the like and may be any suitable gas, such as compressed air or nitrogen.

[0035] In the embodiment depicted in FIG. 2, the nozzle configuration 40 has a single nozzle 41. The single nozzle 41 is fluidly connected to a liquid flow source 60 via a tube 61 and a switch 55, and is connected to a gas flow source 70 via a tube 71 and a switch 55. The switch 55 may be controlled by a controller 50, which, as described above, periodically switches the liquid flow source 60 and the gas flow source 70 in order to generate a pulsed fluid stream that alternates between liquid pulses and gas pulses. Alternatively, the switch 55 may be an automatic valve, or a valve that responds to the liquid pressure and gas pressure generated by the liquid flow source 60 and the gas flow source 70, respectively. As a result, a fluid stream with a higher pressure, such as a liquid stream or a gas stream, causes the switch to open. The nozzle 41 may have any suitable diameter d, for example, a diameter in the range of 0.1 to 1 mm. The smaller the diameter, the less liquid is required for subgingival cleaning. The larger the diameter, the shorter the duration of subgingival cleaning. In this embodiment, the duration of the gas pulse is preferably in the range of 5 to 20 ms in order to allow the discharge of residual liquid from the single nozzle 41 before effectively removing the liquid column from the periodontal pocket. This is because the residual liquid present in the nozzle 41 may disrupt the gas pocket and impair the effective removal of the liquid column from the periodontal pocket.

[0036] In another set of embodiments, switch 55 may be omitted from the single nozzle design. For example, both the liquid flow source 60 and the gas flow source 70 may be directly fluidly connected to a single nozzle 41. The gas flow source 70 generates a gas flow at a pressure below the peak pressure of the liquid pulse generated by the liquid flow source. As a result, due to the generation of a liquid pulse having a higher pressure than the gas flow, the liquid pulse is forced to pass through the single nozzle 41. On the other hand, at the end of the liquid pulse, the liquid flow pressure is brought to drop below the gas flow pressure, for example, to about 0 bar, and the gas flow can exit the single nozzle 41. As a result, the fluid stream generated at the output of the single nozzle 41 has a stream of liquid pulses interspersed with a gas flow to remove the liquid column from the periodontal pocket, as described above. To minimize the nozzle volume in which the liquid is removed by the gas flow between the liquid pulses, the gas flow preferably enters the nozzle 41 proximal to the orifice. A one-way valve may be present at this inlet to prevent liquid from entering the branch of the nozzle configuration where the gas flow enters the portion of the single nozzle 41 shared with the liquid flow.

[0037] When the gas flow and the liquid flow share a large path through the single nozzle 41, the gas flow and the liquid flow may be alternating flows having the same pressure in the nozzle lumen. This has the advantage that the removal of liquid from the periodontal pocket requires a short time, but has the disadvantage that a gas pressure higher than the pressure strictly required for the removal of liquid from the periodontal pocket is developed, compromising the energy efficiency of the subgingival cleaning system 10 (comprises).

[0038] In another embodiment depicted in FIG. 3, the nozzle configuration 40 has a first nozzle 42 fluidly coupled to a liquid flow source 60 via a tube 61 and a second nozzle 43 fluidly coupled to a gas flow source 70 via a tube 71. The liquid flow source 60 can have a liquid pump 64, such as a water pump, configured to deliver liquid from a liquid reservoir 62 to the first nozzle 42, while the gas flow source 70 can have a gas pump 74, such as an air pump, configured to draw gas (here air) into the tube 71 via an inlet 73. The controller 50 may be configured to control the liquid flow source 60, such as the liquid pump 64, and the gas flow source 70, such as the gas pump 74, to generate a fluid flow containing liquid pulses separated by air as described above. Alternatively, the gas pump 74 can respond to the liquid pressure generated by the liquid pump 64, as will be described in more detail below. The liquid pump 64 and the gas pump 74 can take any suitable shape, for example, they can be piston pumps or plunger pumps. Such pumps are well known in themselves and will not be described in detail for the sake of brevity. Further, although the gas pump 74 is shown separately, this is merely a non-limiting illustration, and it should be noted that, for example, integrating the air pump 74 into the water flow source 70 is equally feasible. In this embodiment, the gas flow may be pulsed or continuous. In the case of a continuous gas flow, care must be taken so that the gas flow does not disrupt the liquid pulses, which can be achieved by limiting the gas flow velocity at the tip of the second nozzle 43 to 100 m / s or the pressure at this tip to 0.1 bar. In the case of a pulsed gas stream, a higher gas velocity at the tip of the nozzle 43 may be used, which therefore has the advantage of a faster removal of the liquid column from the periodontal pocket. This thus contributes to a shorter duty cycle (higher frequency) of the pulsed fluid stream and a reduction in the overall cleaning time for the patient. The first nozzle 42 may have a tip diameter d in the range of 0.1 to 1 mm, and the second nozzle 43 may have a tip diameter d' in the range of 0.1 to 1 mm. The diameters d and d' can be the same or different.

[0039] The first nozzle 42 and the second nozzle 43 are typically configured to target the subgingival area to be cleaned, such as a periodontal pocket, together. For this reason, the first nozzle 42 and the second nozzle 43 can be closely aligned, or alternatively, the first nozzle 42 and the second nozzle 43 target the subgingival area to be cleaned from the opposite side of this area, which can, for example, assist in the correct targeting of the nozzle configuration 40 in the subgingival area to be cleaned. In a specific embodiment schematically depicted in FIG. 6, the nozzle configuration 40 is a concentric nozzle configuration in which the second nozzle 43 encloses the first nozzle 42. Of course, the first nozzle 42 can alternatively enclose the second nozzle 43, but it is preferred that the liquid pulse is supplied through the inner nozzle of the concentric nozzle configuration 40. This is because this ensures that a particularly concentrated liquid pulse is delivered to the subgingival area to be cleaned and aids in the efficient cleaning of this area.

[0040] By controlling the shape of the liquid pulse, the cleaning efficiency of the liquid pulse can be further improved. The liquid pulse train preferably resembles a square wave, and the pressure tail of the liquid pulse is minimized as much as possible. This is because a relatively long tail in which the pressure of the liquid pulse gradually decreases reduces the cleaning efficiency of such a liquid pulse. The tail of the liquid pulse can be appropriately formed in a plurality of suitable manners. For example, a positive pressure system including a liquid reservoir 62, a tube 61, and a nozzle configuration 40 can be made non-expandable, so that when the liquid pump 64 is disconnected, the pressure in the tube 61 rapidly decreases. This is because the positive pressure system cannot expand during the prior pumping of the liquid by the liquid pump 64 and thus does not contract when the liquid pump 64 is switched off. Such contraction applies a residual pressure to the liquid remaining in the tube 61, resulting in a pressure tail in the liquid pulse, and thus avoiding such contraction using a non-expandable pressure system avoids the generation of such a pressure tail.

[0041] Alternatively or additionally, the fluid path from the liquid flow source 60 to the nozzle configuration 40 may include an active stop 63 under the control of the controller 50, disposed, for example, within the tube 61 as schematically depicted in FIG. 4. Actuation of the active stop 63 at the end of the liquid pulse generation period abruptly halts the flow of liquid from the liquid flow source 70 to the nozzle configuration 40, thereby avoiding a long pressure drop tail for such liquid pulses. Such an active stop 63 can be implemented in a plurality of suitable manners. For example, the active stop 63 may be a valve such as a block valve or a pressure relief valve. Alternatively, the active stop 63 may be a pull-back piston. Such a pull-back piston may be disposed at a branch of the tube 61 and can be pulled back to create a negative pressure within the tube 61, thereby preventing liquid from exiting the first nozzle 42. The pull-back piston may alternatively form part of the liquid pump 64, for example, the same piston may be used to generate liquid pressure while operating the liquid pump 64 to form liquid pulses. The piston can be moved in the reverse direction to draw the liquid within the tube 61 and the second nozzle 42 back towards the liquid reservoir 62, thereby rapidly reducing the hydraulic pressure within the tube 61.

[0042] In the gingival sulcus cleaning system 10 according to an embodiment of the present invention, the gas pressure can be generated in a plurality of suitable manners. As shown above, the gas pump 74 can draw in air through the air inlet 73 and generate a desired pulsed or continuous gas flow. In an alternative embodiment schematically depicted in FIG. 5, the gas flow source 70 has a gas pump 74 fluidly coupled to a gas reservoir 72, such as a gas canister, containing the gas used to generate the gas pressure within the tube 71. In this embodiment, the gas pump 74 can be replaced under the control of a valve or the like or the controller 50 when the gas canister 72 is pressurized such that a separate pump is not required.

[0043] In a further embodiment schematically depicted in FIG. 7, the air pump 74 may form part of the nozzle configuration 40. This nozzle configuration 40 may be detachable. As a result, the nozzle configuration 40 can be attached to an existing oral hygiene device such as a water flushing jet device. A battery (not shown) for supplying power to the gas pump 74 can be incorporated into this nozzle configuration 40. For example, this embodiment is particularly feasible when the gas pump 74 provides a continuous gas stream, where the controller 50 only controls the liquid flow source 70 to generate the liquid pulse train described above. Alternatively, the gas pump 74 in this embodiment can have an air piston driven by the liquid pressure generated by the liquid pump 64 via the nozzle configuration 40. As a result, an air pulse is formed prior to each water pulse, forming a fluid stream consisting of alternating liquid / air pulses. This is schematically depicted in FIG. 8, where the first nozzle 42 has an impeller 210 that drives a gear 220 within the second nozzle 43, and this gear 220 is coupled to the serrated or toothed edge of the stem 231 of the plunger 232. A spring 240 is wound around the stem 231 and extends between the head of the plunger 230 and the stop 250. The second nozzle 43 further has a first one-way valve 202 acting as a pressure relief valve disposed proximate to its orifice, and a second one-way valve 204 extending through the wall of the second nozzle 43 and acting as an air inlet valve. The second one-way valve 204 is disposed between the first one-way valve 202 and the plunger 230.

[0044] In operation, the liquid pulse flowing through the first nozzle 42 acting as a conduit for the liquid pulse rotates the impeller 210. This in turn causes the plunger 230 to be drawn towards the stop 250 in the second nozzle 43 which functions as a compartment for generating a stream of air pulses, driving the gear 220. Thereby, the coil spring 240 is compressed. The suction generated by the plunger 230 in this way closes the first one-way valve 202 and sucks air into the (expanding) volume within the second nozzle 43 between the first one-way valve 202 and the plunger 230. The force exerted by the liquid pulse on the impeller 210 is typically greater than the compression force of the coil spring 240. As a result, the coil spring 240 remains compressed and the plunger remains biased against the stop 250 while the liquid pulse is flowing. When the liquid pulse ends, the impeller 210 is no longer driven by the liquid pressure, and as a result, the energy stored in the coil spring 240 is released, causing the gear 220 to rotate in the reverse direction. That is, the release of the plunger 230 is caused, which forces the air in the above-mentioned volume within the second nozzle 43 to be discharged therefrom by closing the second one-way valve 204 and opening the first one-way valve 202. Thereby, an air pulse exiting from the second nozzle 43 through its orifice is generated.

[0045] In another exemplary embodiment schematically depicted in FIG. 9, a flexible membrane 46 is attached to a partition wall 44 between a first nozzle 42 acting as a conduit for liquid pulses and a second nozzle 43 acting as a compartment. In this case, air pulses are generated proximate to the orifice 48 of the nozzle configuration 40 and the outer wall 45 of the nozzle configuration 40 so as to provide access 47 to the space between the partition wall 44 and the flexible membrane 46. As before, the second nozzle 43 has a first one-way valve 202 disposed proximate to the nozzle orifice 48 and a second one-way valve 204 extending through the outer wall 45 that allows air to enter the second nozzle 43. As indicated by the block arrows, during the flow of the liquid pulse through the first nozzle 42 (situation A), the liquid pulse pressure causes a portion of the liquid to enter the space between the partition wall 44 and the flexible membrane 44. Thereby, this space is expanded. This results in the flexible membrane 46 exerting a positive pressure on the air within the second nozzle 43. Consequently, the opening of the first one-way valve 202 and the discharge of the air pulse from the nozzle configuration 40 through its orifice 48 are triggered. At the same time, the second one-way valve 204 that allows air to enter the second nozzle 43 is closed.

[0046] At the end of the liquid pulse (situation B), the extended membrane 46 exerts a positive pressure on the liquid within the space between the partition wall 44 and the flexible membrane 46, and thus this liquid is forced to move from this space through the access 47 into the first nozzle 42. As a result, the pressure within the second nozzle 43 decreases, causing the closure of the first one-way valve 202 and the opening of the second one-way valve 204, enabling air to enter the second nozzle 43. This typically occurs when the internal pressure within the second nozzle 43 drops below atmospheric pressure. Thus, a stream of air pulses that partially overlaps the liquid pulse can be generated, such that, as a result, after each liquid pulse, the air pulse tail can remove the liquid column from the periodontal pocket.

[0047] These exemplary embodiments of the nozzle configuration 40 thus enable an existing subgingival cleaning system capable of generating a stream of liquid pulses to be adapted such that the liquid pulses are separated from air, e.g., a continuous air stream or a pulsed air stream, in order to remove the liquid column from the periodontal pocket to be cleaned. In such a nozzle configuration 40, the first nozzle 42 typically functions as a conduit for the liquid pulses and the second nozzle 43 typically functions as a compartment in which air pulses are created. This compartment typically has some pressurizing configuration, e.g., a plunger 230 or a flexible membrane 46, that responds to the liquid pressure created by the liquid pulses in order to pressurize the air within the compartment to generate a stream of air pulses through the pressure relief valve 202. Each air pulse at least partially follows one of the liquid pulses. For example, in the plunger embodiment of FIG. 8, the air pulses are substantially temporally distinct from the liquid pulses. In the flexible membrane embodiment of FIG. 9, the air pulses are temporally overlapping with the liquid pulses. In the latter embodiment, it has been found that the non-overlapping tails of the air pulses can still effectively remove at least a portion of the liquid column from the periodontal pocket and improve the cleaning performance of a subgingival cleaning device that delivers only the liquid pulses.

[0048] The subgingival cleaning system 10 of the present invention can take any suitable shape or form and is not limited to dedicated subgingival cleaning. For example, as schematically depicted in FIG. 10, the subgingival cleaning system 10 may be incorporated into an electric toothbrush. The nozzle configuration 40 extends through the stem 82 of the brush attachment 80. The nozzle 41 terminates at the brush head 84 of the brush attachment 80. The battery compartment 12 is configured to power a motor (not shown) for driving the brush attachment 80, the controller 50, the liquid flow source 60, and, where relevant, the gas flow source 70 to generate a fluid stream having a liquid pulse separated by air that reaches the nozzle configuration 40 through the fluid conduits 61, 71. As will be readily understood by those skilled in the art, although a single nozzle 41 is shown as terminating substantially centrally within the brush head 84, other arrangements, such as dedicated nozzles for a pulsed liquid stream and a continuous or pulsed air stream terminating at any suitable location within the brush head 84, are equally feasible.

[0049] At this point, it should be further noted that the subgingival cleaning system 10 according to an embodiment of the present invention need not be dedicated to subgingival cleaning and may instead have a plurality of oral cleaning modes, such as a continuous cleaning mode and a pulse cleaning mode where the liquid pulse is not separated by a gas stream or gas pulse. At least some of these other oral cleaning modes may not be intended for subgingival cleaning.

[0050] For the purpose of proof of concept, computational fluid dynamics was performed on a CAD model of a second molar pocket as shown in FIG. 11. The mesial direction is indicated by the block arrow labeled M, and the distal direction is indicated by the block arrow labeled D. The CAD model includes an interdental periodontal pocket with a depth of 5 mm as indicated by the arrow, and the remaining pocket depth around the tooth is 3 mm. The width of the interdental periodontal pocket tapers from 0.4 mm at the top of the pocket to 0.1 mm at the bottom. The interdental surface between the two teeth is indicated by a dashed line.

[0051] In the first set of simulations, the efficiency of a water jet generating a continuous water stream was simulated. To clean an interdental pocket with a depth of 5 mm, the simulations were performed using nozzles of different sizes at nearly optimal aiming positions. With nozzles of 0.8 mm and 0.3 mm in diameter, complete pocket cleaning was achieved with liquid volumes of 12.6 ml and 4.2 ml, and in approximately 0.92 seconds and 2.33 seconds, respectively. For the treatment of local pockets, such treatment times and volumes are not problematic. However, when cleaning a complete set of teeth with up to 60 interdental pockets, using water jets with nozzle diameters of 0.3 mm and 0.8 mm requires treatment times of 140 seconds and 55 seconds, respectively, and water volumes of 252 ml and 756 ml. Considering the cleaning of the subgingival regions on the buccal and lingual gingival margins, the treatment time and required water volume further increase. Furthermore, in the buccal and lingual regions, the optimal aiming angle needs to be recalculated, which may result in an increase in treatment time. Such treatment times can be further lengthened depending on the user's behavior and the anatomical structure of the tooth-pocket. The large volume of liquid and long treatment times impair the user experience and, as a result, reduce the user compliance rate of the required oral hygiene management, which is the key to achieving a true oral hygiene solution. Therefore, there is a strong need to enhance the effectiveness of jet pocket cleaning by reducing the treatment time and required water volume.

[0052] One of the findings obtained from the first set of simulations is that the velocity of the liquid rapidly decreases after entering the interdental periodontal pocket. The liquid flow exits the nozzle at 25 m / s and decelerates to below 10 m / s at the bottom of the pocket. This is due to the fact that the jet has to penetrate a liquid column with a height of 5 mm within the pocket, which results in a loss of momentum due to the surface resistance caused by the pocket walls and the liquid present within the pocket, reducing the velocity of the liquid. Consequently, the resulting shear force at the bottom of the pocket acting on the biofilm decreases, leading to a slower cleaning of the periodontal pocket.

[0053] In a second set of simulations, the performance of the subgingival cleaning system 10 (labeled AAW) according to an embodiment of the present invention was compared with the performance of a continuous water jet (labeled WJ). This is schematically shown in FIG. 12, where the subgingival cleaning system 10 comprises a pair of adjacent nozzles 42, 43, and the water nozzles have a diameter of 0.55 mm, the same as the diameter of the water jet nozzle 5. The air velocity from the adjacent air nozzles was set at 100 m / s (0.1 bar) at the nozzle outlet and was found to be sufficient to remove fluid from the interdental periodontal pocket. The pulse durations of the water pulse and the air pulse were each set at 10 ms. Thereby, a pulsed fluid stream having a 50 Hz cycle frequency is obtained. As shown in the right panel of FIG. 12, biofilm removal was established in three different regions of the interdental periodontal pocket. That is, the upper part (I) of the pocket is in the range of 0 to 1.5 mm measured from the pocket inlet, the middle or middle part (II) of the pocket is in the range of 1.5 to 3 mm measured from the pocket inlet, and the deep or bottom part (III) of the pocket is in the range of 3 to 5 mm measured from the pocket inlet.

[0054] The results of these simulations are shown in FIG. 13. This shows the amount of biofilm removal (y-axis, %) as a function of the amount of water used (x-axis, grams) for the deep pocket (upper left), middle pocket (upper right), upper pocket (lower left), and total pocket (lower right). FIG. 14 shows the area of the pocket cleaned (y-axis, %) as a function of the amount of water used (x-axis, grams) for the deep pocket (upper left), middle pocket (upper right), upper pocket (lower left), and total pocket (lower right). From these graphs, it can be clearly recognized that for the upper pocket, both the subgingival cleaning system 10 according to an embodiment of the present invention and the continuous water jet achieve complete removal of biofilm with about 1 g (1 ml) of water. However, for both the middle pocket and the deep pocket, the subgingival cleaning system 10 achieves excellent cleaning results. In particular, for the cleaning of the deep pocket, about 70% of the biofilm is removed with 1.5 g (1.5 ml) of water, while for the continuous water jet when using the same amount of water, it is 50% or less. This corresponds to about 40% of the total area of the deep pocket being cleaned by the subgingival cleaning system 10 compared to about 15% of this total area being cleaned by the continuous water jet using the same amount of water. Therefore, removing the water column from the periodontal pocket using gas (e.g., air) during the liquid (e.g., water) pulses emitted into this pocket significantly improves the cleaning efficiency of the subgingival cleaning system 10 compared to a continuous water jet using the same nozzle diameter and amount of water. As a result, when using the subgingival cleaning device 10 instead of the continuous water jet, effective periodontal disease cleaning can be achieved in a short time using less liquid (e.g., water).

[0055] FIG. 15 is a flowchart of method 100 according to an embodiment, which is a method for effective subgingival cleaning and can be implemented in any suitable manner, for example, by subgingival cleaning system 10. Method 100 is started, for example, in operation 101 by enabling a device or system by which the user implements method 100. In operation 103, a liquid pulse having a duration in the range of 8 to 40 ms is directed at the subgingival area to be cleaned, while in operation 105, gas is directed at the subgingival area to be cleaned after each liquid pulse. Thereafter, method 100 returns to operation 103 until it is determined in operation 107 that the fluid stream should be terminated, for example, based on a user command, and then method 100 ends in operation 109. During the repetition of operation 103, i.e., the interval between subsequent liquid pulse generations, typically has a duration of 2 to 10 ms, which, as explained above, is long enough for the gas in operation 105 to remove the liquid column from the periodontal pocket of the subgingival area to be cleaned. The gas provided in operation 105 may be provided as a continuous gas stream or may have the generation of gas pulses between two liquid pulses. The gas pulse has a duration in the range of 2 to 10 ms, i.e., the duration of the interval between two subsequent liquid pulses.

[0056] The above-described embodiments are illustrative rather than limiting of the invention, and it should be noted that those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps other than those listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by hardware having several different elements. In a device claim listing several means, several of these means may be embodied by the same item of hardware. The means recited in mutually different dependent claims can advantageously be combined.

Claims

1. A subgingival cleaning system comprising: A liquid flow source and a gas flow source each coupled to a nozzle configuration directed at a subgingival region to be cleaned, the nozzle configuration including at least one nozzle, the liquid flow source and the gas flow source; A controller, wherein the controller is configured to: Cause the liquid flow source to generate a liquid flow including a series of liquid pulses through the nozzle configuration; Cause the gas flow source to generate the gas flow through the nozzle configuration such that each liquid pulse is followed by a gas flow; Operate such that each liquid pulse has a duration of 5 to 100 ms and the interval between successive liquid pulses each has a duration of 1 to 50 ms, a subgingival cleaning system.

2. The subgingival cleaning device according to claim 1, wherein each liquid pulse has a duration of 8 to 40 ms and the interval between a series of liquid pulses each has a duration of 2 to 10 ms.

3. The subgingival cleaning device according to claim 1 or 2, wherein the nozzle configuration has a single nozzle.

4. The subgingival cleaning device according to claim 3, wherein the liquid flow source and the gas flow source are fluidly coupled to the single nozzle via a switch that switches between the liquid flow and the gas flow.

5. The subgingival cleaning device according to claim 1 or 2, wherein the nozzle configuration has a first nozzle fluidly coupled to the liquid flow source and a second nozzle fluidly coupled to the gas flow source.

6. The subgingival cleaning device according to claim 5, wherein the nozzle configuration has a concentric nozzle configuration in which one of the first nozzle and the second nozzle surrounds the other.

7. The subgingival cleaning system according to any one of claims 1 to 6, wherein the gas flow from the gas flow source has a plurality of gas pulses, and each gas pulse at least partially follows one of the liquid pulses.

8. The subgingival cleaning device according to claim 5 or 6, wherein the gas flow from the gas flow source is a continuous gas flow.

9. The subgingival cleaning system according to any one of claims 1 to 8, wherein the liquid is water and / or the gas is air.

10. The subgingival cleaning system according to any one of claims 1 to 9, wherein the liquid flow source has a liquid reservoir fluidly coupled to the nozzle configuration via a fluid connection including a liquid pump.

11. The fluid connection, the liquid flow source, and the nozzle configuration are non-expandable, and / or The subgingival cleaning system according to claim 10, wherein the fluid connection has an active stop that stops the liquid flow from the liquid flow source to the nozzle configuration under the control of the controller.

12. The subgingival cleaning system according to any one of claims 1 to 11, wherein the gas flow source has an air piston in the nozzle configuration, the air piston is driven by a liquid pressure generated by the liquid flow source, and the air piston is caused to draw air into the nozzle configuration.

13. The subgingival cleaning system according to any one of claims 1 to 11, wherein the gas flow source has a gas pump or a gas canister.

14. The subgingival cleaning system according to claim 13, wherein the gas pump is integrated into the nozzle configuration.

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