Subgingival cleaning

Abstract

A subgingival cleaning system (10) for cleaning subgingival areas such as periodontal pockets is disclosed. The system comprises 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) which is arranged to be directed at a subgingival area to be cleaned, the nozzle arrangement comprising at least one nozzle (41, 42, 43). The system is configured for generating a liquid flow comprising a series of liquid pulses from the liquid flow source, each liquid pulse having a duration of 5-100 ms, preferably 8-40 ms, wherein the interval between subsequent liquid pulses is 1-50 ms, preferably 2-10 ms; and a gas flow from the gas flow source filling at least part of the interval. Also disclosed is a nozzle arrangement for forming such a subgingival cleaning system.

Description

Technical Field

[0001] The present invention relates to a subgingival cleaning system comprising a liquid flow source coupled to a nozzle device arranged to be aimed at the subgingival region to be cleaned, the nozzle device comprising at least one nozzle.

[0002] The present invention also relates to a nozzle device for cleaning such subgingival areas. Background Technology

[0003] Periodontitis is a common gum infection with a high prevalence worldwide. For example, in the United States, nearly half (46%) of adults over the age of 30 are diagnosed with periodontitis, raising public health concerns. Periodontitis is irreversible because the breakdown of the tooth's supporting tissues cannot fully recover. This leads to the gums separating from the teeth, creating gaps between the tooth surface and the gums. These gaps, called periodontal pockets, create favorable microenvironments for the growth of specific bacterial species, which, as gum disease progresses, contribute to tooth loosening or even loss.

[0004] In addition to a large number of patients diagnosed with periodontitis, another significant number have periodontitis or early pocket formation that goes unrecognized by patients or professionals. For these patients, extra oral hygiene is crucial to prevent these pockets from developing and deepening, which can ultimately lead to severe periodontitis.

[0005] The gold standard for periodontitis treatment is professional scaling and root planing. This treatment involves the experienced hands of a dental professional removing tartar and biofilm from the surfaces of the teeth and roots. For successful treatment, patients attend maintenance sessions every 3-4 months, returning for professional cleaning. Studies have shown that patient (16%) have low adherence to one-hour appointments for maintenance treatments lasting 5-14 years. Fear of dentists, financial factors, and the behavior of dental professionals are cited as reasons for low adherence. Therefore, there is a strong need for home cleaning devices for pocket cleaning maintenance treatments. Ideally, such home cleaning devices could also be used to prevent the progression of initial pockets, even before professional scaling and root planing is required.

[0006] Subgingival cleaning targets can be divided into several segments:

[0007] - Subgingival calculus attached to the root of the tooth. This can only be removed professionally.

[0008] -Subgingival plaque is composed of multiple layers:

[0009] a) Basal layer: Adheres directly to the root surface. This layer mainly contains bacteria (benign symbionts) unrelated to gum disease. This layer typically exhibits high toughness.

[0010] b) The intermediate layer mainly contains filamentous or rod-shaped cells. This layer (sometimes called the orange complex) is associated with gingivitis and exhibits moderate toughness.

[0011] c) The top layer, which mainly contains filamentous, rod-shaped, or even spherical cells. This layer (sometimes called the red complex) is associated with periodontitis and is soft with low toughness.

[0012] d) Several sources have reported additional loose bacterial layers covering the adherent biofilm, which are species strongly associated with periodontitis.

[0013] - Subgingival fluid: Gingival crevicular fluid (GCF) forms in the subgingival suture and pocket, and its formation rate increases with increasing inflammation and pocket depth. Bacterial toxins and other bacterial byproducts can accumulate in the GCF.

[0014] It can be assumed that, combined with occasional tartar removal and professional removal of the strong basal layer, home cleaning devices are sufficient to remove the toxic fluids and softer top layer, which harbor most stubborn periodontal pathogens. Since periodontal pathogens grow slowly and typically require 2-3 days to regrow, cleaning once a day or every few days is adequate. However, for successful cleaning, the entire depth of the pocket must be cleaned to remove pathogens, thus preventing the process of gingival detachment that occurs at the pocket edge. Deep coverage is one of the key challenges of successful cleaning techniques.

[0015] Examples of such household cleaning devices are disclosed in US 2020 / 276003 A1, which discloses an oral irrigator comprising a reservoir, a tip fluidly connected to the reservoir, a motor having a drive shaft, and a pump. In use, the pump generates a jet of water that passes through the tip and is directed by the user into his or her interdental space to perform subgingival cleaning, such as cleaning of the subgingival periodontal pocket.

[0016] However, these types of oral irrigators have been found to be ineffective for cleaning periodontal pockets, even when using specialized subgingival irrigator tips. For example, in patients with moderate periodontitis, the largest group affected by periodontitis, where the deepest pockets are defined as 5 mm deep, these water jet-based oral irrigators have been found unable to clean the full depth of these periodontal pockets, especially when used at an inappropriate alignment angle, thus limiting the effectiveness of the cleaning process performed with these irrigators. While proper alignment improves the effectiveness of the cleaning process with these oral irrigators, different subgingival areas, such as the oral and lingual regions, may require different optimal alignment angles, which may be difficult for users to achieve. Furthermore, effective cleaning of these relatively deep periodontal pockets may require up to 750 ml of water and a treatment time of 140 seconds, which is unsatisfactory from the user's perspective and may prevent users from adhering to the required cleaning rules.

[0017] WO 2013 / 001520 discloses an oral hygiene device that can be controlled to deliver a jet of air or a jet of air and liquid. This has been found to help remove residual food and plaque. Summary of the Invention

[0018] This invention seeks to provide a subgingival cleaning system capable of achieving more effective periodontal pocket cleaning. The invention also seeks to provide a nozzle device for more effective periodontal pocket cleaning. The invention is defined by the independent claims. The dependent claims define advantageous embodiments.

[0019] According to one aspect, a subgingival cleaning system is provided, wherein a liquid flow source and a gas flow source are each fluidly coupled to a nozzle device arranged to be aimed at a subgingival region to be cleaned, the nozzle device including at least one nozzle, wherein the liquid flow source is arranged to generate a liquid flow comprising a series of liquid pulses passing through the nozzle device; and the gas flow source is arranged to generate a gas flow passing through the nozzle device such that each liquid pulse is followed by the gas flow.

[0020] This invention is based on insights gained from simulations that the fluid jet velocity within the periodontal pocket decreases rapidly with increasing pocket depth because the fluid jet must penetrate a fluid column (e.g., a 5mm high column in the periodontal pocket of a patient with moderate periodontitis). This decrease is due to momentum loss caused by surface resistance of the tooth walls and the fluid column, further reducing fluid velocity. Removing the fluid column from the periodontal pocket with gas between fluid pulses ensures that newly arriving fluid pulses can penetrate the pocket depth at an increased velocity, while requiring less fluid due to the pulsatile nature of the fluid flow. Therefore, a subgingival cleaning system is provided that provides improved cleaning of the periodontal pocket with less water and in a shorter time compared to water-flushing cleaning devices.

[0021] To achieve this level of more effective cleaning performance, each liquid pulse has a duration of 5-100 ms, preferably 8-40 ms, and the interval between liquid pulses has a duration of 1-50 ms, preferably 2-10 ms. The liquid pulses are preferably generated at a cycle frequency of 20-100 Hz. If the duration of each liquid pulse is less than 5 ms, effective cleaning of the subgingival region may be compromised, while if the duration of each liquid pulse is greater than 100 ms, the cleaning operation performed with the subgingival cleaning system may take too long and / or use too much liquid. Similarly, if gas is supplied to the subgingival region to be cleaned during intervals of less than 1 ms between liquid pulses, effective removal of the liquid column from the subgingival region to be cleaned may not be achieved, while if gas is supplied to the subgingival region to be cleaned for more than 50 ms, the cleaning operation performed with the subgingival cleaning system may take too long. Limiting the duration of each liquid pulse during which the gas flow is directed to the subgingival region to be cleaned to 8-40 ms and the duration of each interval to 2-10 ms provides a particularly optimal performance window for the subgingival cleaning system.

[0022] In a preferred embodiment, the liquid is water and / or the gas is air, to facilitate particularly direct implementation of the subgingival cleaning system. In the context of water, this can also refer to water-based cleaning agents, such as mouthwash.

[0023] In one embodiment, the nozzle device includes a single nozzle, and wherein the liquid flow source and the gas flow source are optionally fluidly coupled to the single nozzle via a switch arranged to switch between the liquid flow and the air flow. In this embodiment, both the liquid flow and the gas flow are alternating pulsed flows that pass through the same nozzle when delivered to the subgingival region to be cleaned. This is a relatively low-cost implementation of the nozzle device—although it is achieved as a compromise of removing residual liquid in the nozzle by gas when switching from the liquid flow to the gas flow, making effective removal of the liquid column in the periodontal pocket take longer because the delivery of the full air pulse pressure may be delayed due to the initial removal of liquid from the nozzle. Such switching between the fluid flow and the gas flow can be achieved using a switch, or alternatively by inserting the gas flow into the pulsed liquid flow upstream of the single nozzle orifice.

[0024] In an alternative embodiment, the nozzle assembly includes a first nozzle fluidly coupled to a liquid flow source and a second nozzle fluidly coupled to a gas flow source. This has the advantage that the gas flow can be delivered to the subgingival region for cleaning without delay due to the need to remove residual water from the nozzle through which the gas flow passes, thereby further reducing the circulation time required for effective cleaning of the subgingival area.

[0025] The nozzle assembly may include a concentric nozzle arrangement, wherein one of the first and second nozzles surrounds the other, for example, the second nozzle may surround the first nozzle. This provides a particularly compact nozzle design in which the two nozzles are aligned to target the subgingival region to be cleaned. Alternatively, the first and second nozzles may be spatially spaced apart from each other, for example, they may be aligned to target the subgingival region to be cleaned from opposite directions to ensure effective cleaning of the region.

[0026] The gas flow from the gas source may include multiple gas pulses, each gas pulse at least partially following one of the liquid pulses, for example, the duration of the interval between each gas pulse being between the liquid pulses; or alternatively, the gas flow from the gas source may be a continuous gas flow. In the case of a continuous gas flow, the gas pressure is kept sufficiently low, for example, at most 0.1 bar, to prevent the liquid pulses from breaking down into droplets.

[0027] In one particular embodiment, the liquid flow source includes a liquid reservoir fluidly coupled to a nozzle device via a fluid coupler including a liquid pump, such that a liquid pulse can be generated by activating the liquid pump during a defined time period (e.g., the duration of the liquid pulse to be generated).

[0028] Preferably, the generated liquid pulse should, as far as possible, mimic a square wave in the sense that the liquid pulse should decay rapidly, as this improves the cleaning efficiency of the liquid pulse. In one embodiment, a low-pressure tail of the liquid pulse is avoided by means of a fluid coupler, and the liquid reservoir and nozzle device are non-expandable because such non-expandable positive pressure systems for liquids promote a sharp drop in liquid pressure at the termination of liquid pulse generation by preventing volume changes in the positive pressure system during liquid pulse generation. Alternatively or additionally, the fluid coupler between the liquid source and the nozzle device includes an active stop under the control of a controller to terminate the liquid flow from the liquid source to the nozzle device in order to achieve a sharp cutoff of the liquid pulse. Such an active stop may take the form of a valve such as a blocking valve or a pressure relief valve, or a piston such as a pull-back piston that draws liquid out of the nozzle device.

[0029] The gas flow can be generated in several ways. In one embodiment, the gas flow source includes an air piston within a nozzle device, driven by liquid pressure generated by the liquid flow source, causing the air piston to draw air into the nozzle device. This is a particularly cost-effective solution in embodiments where the gas flow is pulsed, because the gas pulse can be generated before the liquid pulse in such devices as the liquid pulse travels toward the nozzle device.

[0030] Alternatively, the gas flow source may include a gas pump or a gas tank, which is advantageous, for example, in embodiments where the gas flow is continuous, although such gas pumps or gas tanks can of course be used equivalently to generate pulsed gas flows.

[0031] In one embodiment, the gas pump is integrated with the nozzle assembly, which has the advantage that the gas pump can be fitted into such a system by attaching the nozzle assembly to an existing subgingival cleaning system.

[0032] According to another aspect, a nozzle device for a subgingival cleaning system is provided, the system being arranged to generate a pulsed flow of liquid. The nozzle device includes 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 terminates in an orifice of the nozzle device. The compartment includes a pressurizing device responsive to liquid pressure generated by the liquid pulses, the pressurizing device pressurizing air within the compartment to generate an air pulse flow through the pressure relief valve. Each air pulse at least partially follows one of the liquid pulses. Such a nozzle device can be deployed with 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, which can remove a column of water from the subgingival region to be cleaned, as previously explained.

[0033] Another method for cleaning the subgingival region includes directing a fluid flow toward the subgingival region, the fluid flow comprising a series of liquid pulses; and a gas flow following each liquid pulse, wherein the gas flow comprises multiple gas pulses, for example, each gas pulse having a duration equal to the interval between subsequent liquid pulses, or a continuous gas flow. This type of cleaning method has been found to effectively remove debris from the subgingival region that is most likely to cause periodontitis, and therefore, periodic use of this method, such as daily or every other day, can help control periodontitis in patients. Attached Figure Description

[0034] Embodiments of the invention will be described in more detail by way of non-limiting example with reference to the accompanying drawings, in which:

[0035] Figure 1 A subgingival cleaning system according to one embodiment is schematically depicted;

[0036] Figure 2 An aspect of a subgingival cleaning system according to another embodiment is schematically depicted;

[0037] Figure 3 An aspect of a subgingival cleaning system according to yet another embodiment is schematically depicted;

[0038] Figure 4 An aspect of a subgingival cleaning system according to yet another embodiment is schematically depicted;

[0039] Figure 5 An aspect of a subgingival cleaning system according to yet another embodiment is schematically depicted;

[0040] Figure 6 An aspect of a subgingival cleaning system according to yet another embodiment is schematically depicted;

[0041] Figure 7 An aspect of a subgingival cleaning system according to yet another embodiment is schematically depicted;

[0042] Figure 8 A subgingival cleaning system according to an alternative embodiment is schematically depicted;

[0043] Figure 9 A nozzle device for converting an existing subgingival cleaning system into a subgingival cleaning system is schematically depicted according to an example embodiment;

[0044] Figure 10 Another nozzle device for converting an existing subgingival cleaning system into a subgingival cleaning system, according to an example embodiment, is schematically depicted.

[0045] Figure 11 The molar configuration used in the proof-of-concept computer simulation is schematically depicted;

[0046] Figure 12 A proof-of-concept simulation setup is schematically depicted to compare the performance of a subgingival cleaning system according to one embodiment with that of a water jet.

[0047] Figure 13 and 14 Including depiction and utilization Figure 12 The graphs showing the simulation results obtained from the simulation settings depicted in the figure; and

[0048] Figure 15 This is a flowchart of a subgingival cleaning method according to one embodiment. Detailed Implementation

[0049] It should be understood that the accompanying drawings are schematic only and not drawn to scale. It should also be understood that the same reference numerals are used in all the drawings to denote the same or similar parts.

[0050] Figure 1A subgingival cleaning system 10 according to an embodiment of the present invention is schematically depicted. The subgingival cleaning system 10 includes a base unit 20 and a handheld unit 30 fluidly connected to the base unit 20 via a conduit 25. The base unit 20 may include a user interface 22, such as a dial or knob, through which a user can select an operating mode of the subgingival cleaning system 10. The handheld unit 30 includes a nozzle device 40 having one or more nozzles through which a fluid flow can be directed towards the subgingival region to be cleaned by the user. The handheld unit 30 may include a switch 32 for enabling / disabling such fluid flow. According to the present invention, the subgingival cleaning system 10 includes an operating mode (which may be its only operating mode or may be one of multiple operating modes) wherein a fluid flow is generated through the nozzle device 40, the fluid flow comprising a plurality of liquid pulses separated by gas. The gas may be a continuous gas flow or a pulsed gas flow, such that the fluid flow through the nozzle device 40 consists of a sequence of liquid pulses interspersed with gas pulses. In an alternative embodiment, the base unit 20 may no longer be a separate entity, and its functionality may be integrated into the handheld unit 30.

[0051] It has been found that contaminants in periodontal pockets at depths of 5 mm or greater that contribute to periodontal disease (such as the top plaque layer, an additional loose bacterial layer covering the adherent biofilm, and subgingival fluid) can be removed more effectively with liquid pulses separated by gases, such as gas pulses or continuous gas flows, compared to continuous liquid flows. As previously explained, this can be understood by removing the accumulated fluid from the periodontal pocket by air, thereby reducing resistance and providing an improved pathway for subsequent liquid pulses to deeper areas of such periodontal pockets. Particularly effective cleaning of periodontal pockets is achieved when the duration of the liquid pulse is in the range of 5-100 ms, and preferably in the range of 8-40 ms, and is temporally separated by intervals in the range of 1-50 ms, preferably in the range of 2-10 ms, preferably giving the fluid flow a circulation frequency in the range of 20-100 Hz. As will be readily understood by those skilled in the art, when the gas flow is a pulsed gas flow, the duration of each interval defines the duration of the gas pulse. In a preferred embodiment, the duration of such intervals, such as gas pulses, is in the range of 2-4 ms. The effects and advantages of this type of pulsed fluid flow in periodontal pocket cleaning will be shown in more detail below. In embodiments of the invention, the liquid may be water and the gas may be air, but alternatives are also considered. For example, the liquid may be a water-based cleaning liquid, water, or any other suitable liquid, while the gas may be provided by a gas canister or the like, and may be any suitable gas, such as compressed air or nitrogen.

[0052] exist Figure 2In the depicted embodiment, the nozzle assembly 40 includes a single nozzle 41. The single nozzle 41 is fluidly connected to a liquid flow source 60 via a conduit 61 and a switch 55, and to a gas flow source 70 via a conduit 71 and a switch 55. The switch 55 may be controlled by a controller 50 that periodically switches between the liquid flow source 60 and the gas flow source 70 to generate a pulsed fluid flow with alternating liquid and gas pulses as explained above. Alternatively, the switch 55 may be an automatic valve or a valve responsive to the liquid pressure and gas pressure generated by the liquid flow source 60 and the gas flow source 70, respectively, such that a higher-pressure fluid flow (e.g., liquid or gas flow) causes the switch to open. The nozzle 41 may have any suitable diameter d, for example, in the range of 0.1-1 mm. A smaller diameter requires less liquid for the subgingival cleaning operation. A larger diameter results in a shorter duration of the subgingival cleaning operation. In this embodiment, the duration of the gas pulse is preferably in the range of 5-20 ms, so as to allow residual liquid to be discharged from a single nozzle 41 before the liquid column is effectively removed from the periodontal pocket, since residual liquid present in nozzle 41 can interfere with the gas bag and impair the effective removal of the liquid column from the periodontal pocket.

[0053] In another set of embodiments, switch 55 may be omitted from the single nozzle design. For example, liquid flow source 60 and gas flow source 70 may be directly fluidly connected to a single nozzle 41, wherein gas flow source 70 generates a gas flow at a pressure lower than the peak pressure of the liquid pulse generated by the liquid flow source, such that when a liquid pulse with a pressure higher than the gas flow is generated, the liquid pulse is forced through the single nozzle 41, and when the liquid pulse terminates, it causes the liquid flow pressure to drop below the gas flow pressure, for example, to about 0 bar, and the gas flow can now exit the single nozzle 41, such that the fluid flow generated at the output end of the single nozzle 41 includes a liquid pulse flow mixed with the gas flow to remove a column of liquid from the periodontal pocket, as previously explained. To minimize the nozzle volume to be cleared by the gas flow between liquid pulses, the gas flow preferably enters the nozzle 41 near its orifice. A one-way valve may be present at this entry point to prevent liquid from entering a branch of the nozzle assembly through which the gas flow enters the portion of the single nozzle 41 shared with the liquid flow.

[0054] If the gas flow and liquid flow share a larger path through a single nozzle 41, the gas flow and liquid flow can be alternating flows with the same pressure within the nozzle cavity. This has the advantage of requiring less time to remove liquid from the periodontal pocket, but has the disadvantage of requiring a higher gas pressure than strictly necessary for removing liquid from the periodontal pocket, which affects the energy efficiency of the subgingival cleaning system 10.

[0055] exist Figure 3In another depicted embodiment, the nozzle assembly 40 includes a first nozzle 42 fluidly coupled to a liquid flow source 60 via a conduit 61 and a second nozzle 43 fluidly coupled to a gas flow source 70 via a conduit 71. The liquid flow source 60 may include a liquid pump 64, such as a water pump, arranged to pump liquid from a liquid reservoir 62 to the first nozzle 42, while the gas flow source 70 may include a gas pump 74, such as an air pump, arranged to draw gas (here, air) through an inlet 73 into the conduit 71. A controller 50 may be arranged to control the liquid flow source 60 (e.g., liquid pump 64) and the gas flow source 70 (e.g., gas pump 74) to generate a fluid flow comprising liquid pulses separated by air, as explained above. Alternatively, the gas pump 74 may be responsive to liquid pressure generated by the liquid pump 64, which will be explained in more detail below. The liquid pump 64 and the gas pump 74 may take any suitable form, such as piston or plunger pumps. Since such pumps are well-known, they will not be described in further detail for the sake of brevity. It should also be noted that although the gas pump 74 is shown as a separate entity, this is merely a non-limiting example, and it is equally feasible to incorporate the gas pump 74 into the water source 70, for example. In this embodiment, the gas flow can be pulsed or continuous. In the case of a continuous gas flow, care must be taken to ensure that the gas flow does not interfere with the liquid pulse, which can be achieved by limiting the gas flow velocity at the tip of the second nozzle 43 to 100 m / s or a pressure of 0.1 bar at that tip. For a pulsed gas flow, a higher gas velocity can be used at the tip of the nozzle 43, which has the advantage of removing the liquid column from the periodontal pocket more quickly, thus contributing to a shorter duty cycle (higher frequency) of the pulsed fluid flow, thereby reducing the patient's total cleaning time. The tip diameter d of the first nozzle 42 can be in the range of 0.1-1 mm, and the tip diameter d' of the second nozzle 43 can be in the range of 0.1-1 mm. Diameters d and d' can be the same or different.

[0056] The first nozzle 42 and the second nozzle 43 are typically arranged such that they are both aligned with the subgingival region to be cleaned, such as a periodontal pocket. For this purpose, the first nozzle 42 and the second nozzle 43 may be closely aligned, or alternatively, the first nozzle 42 and the second nozzle 43 may be aligned with the subgingival region to be cleaned from opposite sides of the region, which, for example, can help with proper alignment of the nozzle device 40 at the subgingival region to be cleaned. Figure 6 In a particular embodiment schematically depicted, the nozzle device 40 is a concentric nozzle device, wherein the second nozzle 43 surrounds the first nozzle 42. Of course, the first nozzle 42 may alternatively surround the second nozzle 43, although it is preferred that the liquid pulse is delivered through the inner nozzle of the concentric nozzle device 40, as this ensures that a particularly concentrated liquid pulse is delivered to the subgingival region to be cleaned, which contributes to effective cleaning of the region.

[0057] The cleaning efficiency of the liquid pulses is further improved by controlling the shape of the liquid pulses. The liquid pulse train preferably mimics a square wave, wherein the pressure tail of the liquid pulse is minimized as much as possible, because a relatively long tail with a slow pressure drop reduces the cleaning efficiency of such liquid pulses. The tail of the liquid pulse can be suitably shaped in a variety of appropriate ways. For example, the positive pressure system including reservoir 62, pipe 61, and nozzle assembly 40 can be non-expandable, so that the pressure in pipe 61 drops rapidly when liquid pump 64 is disengaged, because the positive pressure system cannot expand during the previous pumping of liquid by liquid pump 64, and therefore will not contract when liquid pump 64 is shut down. Such contraction can exert residual pressure on the liquid remaining in pipe 61, causing a pressure tail in the liquid pulse; therefore, the generation of such a pressure tail is avoided by using a non-expandable pressure system to prevent such contraction.

[0058] Alternatively or additionally, the fluid path from the liquid source 60 to the nozzle assembly 40 may include an active stop 63 under the control of the controller 50, for example located at... Figure 4 The liquid flow is schematically depicted within the conduit 61. At the end of the liquid pulse generation cycle, an active stop 63 is activated to abruptly stop the liquid flow from the liquid source 70 to the nozzle assembly 40, thereby avoiding the long pressure drop tail of such liquid pulses. This active stop 63 can be implemented in various suitable ways. For example, the active stop 63 can be a valve such as a blocking valve or a pressure relief valve. Alternatively, the active stop 63 can be a pull-back piston. This pull-back piston can be located in a branch of the conduit 61 and can be pulled back to create a negative pressure in the conduit 61, thereby preventing liquid from leaving the first nozzle 42. The pull-back piston can alternatively be formed as part of a liquid pump 64, for example, as the same piston used to generate liquid pressure during the activation of the liquid pump 64 to form a liquid pulse, wherein the piston moves in the opposite direction to draw liquid from the conduit 61 and the second nozzle 42 back toward the liquid reservoir 62, thereby rapidly reducing the liquid pressure in the conduit 61.

[0059] In the subgingival cleaning system 10 according to an embodiment of the present invention, gas pressure can be generated in various suitable ways. As shown above, the gas pump 74 can draw in air through the air inlet 73 to generate a desired pulsed or continuous gas flow. Figure 5 In an alternative embodiment schematically depicted, the gas flow source 70 includes a gas pump 74 fluidly coupled to a gas reservoir 72, such as a gas tank containing gas for generating gas pressure in the conduit 71. In this embodiment, the gas pump 74 may be replaced by a valve or the control of a controller 50, where the gas tank 72 is pressurized to the point that a separate pump is not required.

[0060] exist Figure 7In another embodiment schematically depicted, the air pump 74 may be part of the nozzle assembly 40, which may be detachable, allowing the nozzle assembly 40 to be attached to existing oral hygiene devices, such as water rinsing jet devices. A battery (not shown) may be incorporated into the nozzle assembly 40 to power the air pump 74. This embodiment is particularly feasible, for example, where the air pump 74 provides a continuous flow of gas, wherein the controller 50 controls only the liquid flow source 70 to generate the previously described sequence of liquid pulses. Alternatively, the air pump 74 in this embodiment may include an air piston driven by the liquid pressure generated by the liquid pump 64 through the nozzle assembly 40, such that an air pulse is formed before each water pulse, thereby forming a fluid flow consisting of alternating liquid / air pulses. This is in Figure 8 The diagram schematically depicts a first nozzle 42 including an impeller 210 that drives a gear 220 in a second nozzle 43, the gear 220 being coupled to a serrated or toothed edge of a rod 231 of a plunger 232. A spring 240 is coiled around the rod 231 and extends between the head of the plunger 230 and a stop 250. The second nozzle 43 further includes a first check valve 202 and a second check valve 204, the first check valve serving as a pressure relief valve arranged near its orifice, and the second check valve extending through the wall of the second nozzle 43 and serving as an air inlet valve, the second check valve 204 being located between the first check valve 202 and the plunger 230.

[0061] In operation, the liquid pulse flowing through the first nozzle 42, which serves as a liquid pulse conduit, rotates the impeller 210. This impeller, in turn, drives the gear 220, causing the plunger 230 to be pulled towards the stop 250 within the second nozzle 43, which serves as a compartment for generating gas flow pulses, thereby compressing the helical spring 240. The suction generated by the plunger 230 closes the first one-way valve 202 and draws air into the (expanded) volume within the second nozzle 43 between the first one-way valve 202 and the plunger 230. The force exerted on the impeller 210 by the liquid pulse is typically greater than the compressive force of the helical spring 240, such that the helical spring 240 remains compressed during the liquid pulse flow, and the plunger remains energized against the stop 250. When the liquid pulse terminates, the impeller 210 is no longer driven by liquid pressure, so the energy stored in the helical spring 240 is released, causing the gear 220 to rotate in the opposite direction, that is, causing the plunger 230 to be released. This forces the air in the aforementioned volume in the second nozzle 43 to be discharged through the second one-way valve 204 closing and the first one-way valve 202 opening, thereby generating an air pulse that leaves the second nozzle 43 through its orifice.

[0062] exist Figure 9In another example embodiment, schematically depicted, a flexible membrane 46 is attached to a partition wall 44 between a first nozzle 42 serving as a conduit for liquid pulses and a second nozzle 43 serving as a compartment in which air pulses are generated near the orifice 48 of the nozzle assembly 40 and the outer wall 45 of the nozzle assembly 40, thereby providing a passage 47 to the space between the partition wall 44 and the flexible membrane 46. As previously described, the second nozzle 43 includes a first one-way valve 202 arranged near the nozzle orifice 48 and a second one-way valve 204 extending through the outer wall 45 through which air can enter the second nozzle 43. During the flow of the liquid pulse through the first nozzle 42, as indicated by the box arrow (case A), the liquid pulse pressure causes some liquid to enter the space between the partition wall 44 and the flexible membrane 44, thereby expanding the space. This causes the flexible membrane 46 to exert a positive pressure on the air in the second nozzle 43, thereby triggering the opening of the first check valve 202 and pulsating the air out of the nozzle device 40 through its orifice 48, while closing the second check valve 204, through which air can enter the second nozzle 43.

[0063] When the liquid pulse terminates (case B), the extended membrane 46 applies positive pressure to the liquid in the space between the partition wall 44 and the flexible membrane 46, thereby forcing the liquid from this space into the first nozzle 42 through the passage 47. Consequently, the pressure within the second nozzle 43 drops, causing the first one-way valve 202 to close and the second one-way valve 204 to open, allowing air to enter the second nozzle 43. This typically occurs when the internal pressure within the second nozzle 43 drops below atmospheric pressure. In this way, an air pulse flow that partially overlaps with the liquid pulse can be generated, such that after each liquid pulse, the tail of the air pulse can remove a column of liquid from the periodontal pocket.

[0064] Therefore, these exemplary embodiments of the nozzle device 40 allow existing subgingival cleaning systems capable of generating pulsed liquid flows to be adapted such that the liquid pulses are separated by air (e.g., a continuous flow of air or a pulsed flow of air) to remove a column of liquid from the periodontal pocket to be cleaned. In such nozzle devices 40, a first nozzle 42 typically serves as a conduit for the liquid pulses, while a second nozzle 43 typically serves as a compartment in which air pulses are generated. This compartment typically includes pressurizing devices, such as plungers 230 or flexible diaphragms 46, responsive to the liquid pressure generated by the liquid pulses, for pressurizing the air within the compartment to generate pulsed air flows through a pressure relief valve 202, wherein each air pulse at least partially follows one of the liquid pulses. For example, in Figure 8 In the plunger embodiment, the air pulse is substantially different in time from the liquid pulse, wherein in Figure 9In the flexible membrane embodiment, the air pulse overlaps with the liquid pulse in time. In a later embodiment, it has been found that the non-overlapping tail of the air pulse can still effectively remove at least some of the liquid column from the periodontal pocket, and improves the cleaning performance of subgingival cleaning devices that use only liquid pulses.

[0065] The subgingival cleaning system 10 of the present invention can take any suitable shape or form and is not limited to a dedicated subgingival cleaning system. For example, as Figure 10 As schematically depicted, the subgingival cleaning system 10 can be incorporated into an electric toothbrush, wherein a nozzle assembly 40 extends through a rod 82 of a brush attachment 80, and a nozzle 41 terminates in the brush head 84 of the brush attachment 80. A battery compartment 12 may include a rechargeable battery arranged to power a motor (not shown) for driving the brush attachment 80, controller 50, liquid flow source 60, and, in relevant cases, gas flow source 70, to generate a fluid flow comprising liquid pulses separated by air via fluid conduits 61, 71 into the nozzle assembly 40. As will readily be appreciated by those skilled in the art, although a single nozzle 41 is shown terminating substantially at the center within the brush head 84, other arrangements, such as dedicated nozzles for pulsed liquid flow and continuous or pulsed air flow terminating at any suitable location within the brush head 84, are equally feasible.

[0066] In this regard, it should also be noted that the subgingival cleaning system 10 according to an embodiment of the invention may not be exclusively for subgingival cleaning, but may include a variety of oral cleaning modes, such as a continuous rinsing mode and a pulsed rinsing mode, wherein the liquid pulses are not separated by a gas flow or gas pulses, etc. At least some of these other oral cleaning modes may not be specifically designed for subgingival cleaning.

[0067] To demonstrate proof of concept, for example... Figure 11 The CAD models of the two molar pockets shown are subjected to computational fluid dynamics, with the mesial direction indicated by a hollow arrow labeled M and the distal direction by a hollow arrow labeled D. The CAD model includes an interproximal periodontal pocket with a depth of 5 mm, as indicated by the arrows, with the remaining pocket surrounding the tooth having a depth of 3 mm. The interproximal periodontal pocket is set to have a width of 0.4 mm at the top of the pocket, tapering to 0.1 mm at the bottom. The interdental plane between the two teeth is indicated by a dashed line.

[0068] In the first set of simulations, the efficiency of generating a continuous water jet was modeled. Simulations were conducted using nozzles of different sizes, close to the optimal alignment, to clean interproximal pockets up to 5 mm deep. For nozzles with diameters of 0.8 and 0.3 mm, using liquid volumes of 12.6 ml and 4.2 ml respectively, full pocket cleaning was achieved in approximately 0.92 s and 2.33 s, respectively. For cleaning localized pockets, this processing time and volume may be satisfactory. However, to clean a full set of teeth with up to 60 interproximal pockets, water jets using nozzle diameters of 0.3 mm and 0.8 mm would require processing times of 140 s and 55 s, and water volumes of 252 ml and 756 ml, respectively. If the oral and lingual subgingival regions are also considered for cleaning, the required processing time and water volume will increase further. Furthermore, for the oral and lingual regions, the optimal alignment angle needs to be recalculated, which may lead to increased processing times. These processing times may be further increased due to user behavior and pocket anatomy. Large liquid volumes and long processing times negatively impact the user experience and consequently compromise adherence to desired oral hygiene protocols, which are crucial for achieving a truly effective oral hygiene solution. Therefore, there is a strong need to improve the effectiveness of jet bag cleaning by achieving lower processing times and required water volumes.

[0069] One finding from the first set of simulations is that the fluid velocity decreases rapidly after entering the interproximal periodontal pocket. The fluid flow leaves the nozzle at 25 m / s and then decelerates to less than 10 m / s at the bottom of the pocket. This is because the jet must penetrate a 5 mm high column of fluid within the pocket, which results in momentum loss due to the surface resistance of the pocket walls and the fluid present in the pocket, thus reducing the fluid velocity. Consequently, the shear force acting on the biofilm at the bottom of the pocket is reduced, leading to slower cleaning of the periodontal pocket.

[0070] In the second set of simulations, the performance of the subgingival cleaning system 10 (labeled AAW) according to an embodiment of the invention was compared with the performance of a continuous water jet (labeled WJ). This is in Figure 12 The diagram schematically depicts a subgingival cleaning system 10 configured with a pair of adjacent nozzles 42 and 43. The water nozzle has a diameter of 0.55 mm, the same as the diameter of the water jet nozzle 5. The air velocity from the adjacent air nozzle is set to 100 m / s (0.1 bar) at the nozzle outlet, which has proven sufficient to remove fluid from the interproximal periodontal pockets. The pulse durations of the water pulse and the air pulse are each set to 10 ms, thereby generating a pulsed fluid flow with a circulation frequency of 50 Hz. Figure 12As shown in the right pane, biofilm removal is established in three distinct regions of the interproximal periodontal pocket: the top of the pocket spanning 0–1.5 mm from the pocket entry point (I), the middle or central part of the pocket spanning 1.5–3 mm from the pocket entry point (II), and the deep or bottom part of the pocket spanning 3–5 mm from the pocket entry point (III).

[0071] The results of these simulations are shown in Figure 13 middle, Figure 13 The figure depicts the volume of biofilm removed (y-axis, %) as a function of the volume of water used (x-axis, in grams) for the deep bag (top left), middle bag (top right), top bag (bottom left), and total bag (bottom right). Figure 14 The graphs depict the cleaned area (y-axis, %) of the deep pocket (top left), intermediate pocket (top right), top pocket (bottom left), and total pocket (bottom right) as a function of the volume of water used (x-axis, in grams). From these graphs, it is clear that for the top pocket, both the subgingival cleaning system 10 and the continuous water jet achieve complete removal of the biofilm with approximately 1 g (1 ml) of water. However, for both the intermediate and deep pockets, the subgingival cleaning system 10 achieves excellent cleaning results, particularly for the deep pocket, where approximately 70% of the biofilm is removed with 1.5 g (1.5 ml) of water, compared to less than 50% with the continuous water jet when using the same amount of water. This corresponds to approximately 40% of the total area of ​​the deep pocket cleaned with the subgingival cleaning system 10, compared to approximately 15% of that total area cleaned with the continuous water jet when using the same amount of water. Therefore, compared to a continuous water jet using the same nozzle diameter and water volume, removing a water column from the periodontal pocket using gas (e.g., air) between pulses of liquid (e.g., water) sprayed into the pocket significantly improves the cleaning efficiency of the subgingival cleaning system 10. Thus, when the subgingival cleaning system 10 is used instead of continuous water spraying, effective periodontal cleaning can be achieved in a shorter time using less liquid (e.g., water).

[0072] Figure 15This is a flowchart of method 100 according to one embodiment, a method for effective subgingival cleaning, and can be implemented in any suitable manner, such as by a subgingival cleaning system 10. Method 100 begins with operation 101, for example, by user activation of the device or system implementing method 100. In operation 103, a liquid pulse with a duration in the range of 8-40 ms is directed at the subgingival region to be cleaned, and in operation 105, gas is directed at the subgingival region to be cleaned after each liquid pulse. Thereafter, method 100 returns to operation 103 until, in operation 107, it is determined, for example, in response to a user command, that the fluid flow should be terminated. Thereafter, method 100 terminates in operation 109. The interval between repetitions of operation 103, i.e., the generation of subsequent liquid pulses, typically lasts 2-10 ms, which is long enough for the gas in operation 105 to remove the liquid column from the periodontal pocket in the subgingival region to be cleaned, as previously explained. The gas provided in operation 105 may be provided as a continuous gas flow, or may include generating a gas pulse between two liquid pulses, wherein the gas pulse has a duration of the interval between two subsequent liquid pulses, i.e., the duration is in the range of 2-10 ms.

[0073] It should be noted that the above embodiments are illustrative and not limiting of the invention, and those skilled in the art will be able to devise many alternative embodiments without departing from the scope of the appended claims. Any reference numerals placed in parentheses in the claims should 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 words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements. In device claims listing several means, several of these means may be embodied by the same hardware. Measures recited in mutually different dependent claims may be advantageously combined.

Claims

1. A subgingival cleaning system (10), comprising: A liquid flow source (60) and a gas flow source (70) are each coupled to a nozzle device (40) arranged to be aimed at the subgingival region to be cleaned, the nozzle device including at least one nozzle (41, 42, 43). as well as Controller (50), wherein the controller is configured to operate such that: The liquid flow source is arranged to generate a liquid flow comprising a series of liquid pulses passing through the nozzle assembly; The gas flow source is arranged to generate a gas flow through the nozzle assembly such that each liquid pulse is followed by the gas flow; as well as Each liquid pulse has a duration of 5-100 ms, and the interval between consecutive liquid pulses has a duration of 1-50 ms.

2. The subgingival cleaning system of claim 1, wherein each of the liquid pulses has a duration of 8-40 ms, and the interval between consecutive liquid pulses each has a duration of 2-10 ms.

3. The subgingival cleaning system (10) according to claim 1, wherein the nozzle device (40) comprises a single nozzle (41).

4. The subgingival cleaning system (10) of claim 3, wherein the liquid flow source (60) and the gas flow source (70) are fluidly coupled to the single nozzle via a switch (55) arranged to switch between the liquid flow and the gas flow.

5. The subgingival cleaning system (10) according to claim 1, wherein the nozzle device (40) comprises a first nozzle (42) fluidly coupled to the liquid flow source (60) and a second nozzle (43) fluidly coupled to the gas flow source (70).

6. The subgingival cleaning system (10) according to claim 5, wherein the nozzle device (40) comprises a concentric nozzle device, wherein one of the first nozzle (42) and the second nozzle (43) surrounds the first nozzle and the other of the second nozzle.

7. The subgingival cleaning system (10) according to any one of claims 1-6, wherein the gas flow from the gas flow source (70) comprises a plurality of gas pulses, each gas pulse at least partially following one of the liquid pulses.

8. The subgingival cleaning system (10) according to claim 5 or 6, wherein the gas flow from the gas flow source (70) is a continuous gas flow.

9. The subgingival cleaning system (10) according to any one of claims 1-6, wherein the liquid is water and / or the gas is air.

10. The subgingival cleaning system (10) according to any one of claims 1-6, wherein the liquid source (60) comprises a liquid reservoir (62) fluidly coupled to the nozzle device (40) via a fluid coupler (61) comprising a liquid pump (64).

11. The subgingival cleaning system (10) according to claim 10, wherein: The fluid coupler (61), the liquid flow source (60), and the nozzle device (40) are non-expandable, and / or The fluid coupler includes an active stop (63) which, under the control of the controller (50), terminates the flow of liquid from the liquid source to the nozzle device.

12. The subgingival cleaning system (10) according to any one of claims 1-6, wherein the gas flow source (70) includes an air piston within the nozzle device (40), the air piston being driven by liquid pressure generated by the liquid flow source (60) such that the air piston draws air into the nozzle device.

13. The subgingival cleaning system (10) according to any one of claims 11, wherein the gas flow source (70) comprises a gas pump (74) or a gas tank (72).

14. The subgingival cleaning system (10) according to claim 13, wherein the gas pump (74) is integrated in the nozzle device (40).

15. A nozzle device (40) for a subgingival cleaning system, the nozzle device being arranged to generate a liquid pulse flow, the nozzle device including a conduit (42) for receiving the liquid pulse and a compartment (43) including an air inlet valve (204) and a pressure relief valve (202), each of the conduit (42) and the compartment (43) terminating in an orifice (48) of the nozzle device (40), wherein the compartment includes a pressurizing device responsive to a liquid pressure generated by the liquid pulse, the pressurizing device being used to pressurize air within the compartment to generate an air pulse flow through the pressure relief valve, each air pulse at least partially following one of the liquid pulses, wherein the nozzle device is adapted to generate a flow comprising a series of liquid pulses having a duration of 5-100 ms, wherein the interval between subsequent liquid pulses has a duration of 1-50 ms, each liquid pulse being followed by a gas flow.

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