Root canal cleaning device and operating method thereof

Abstract

Disclosed are a root canal cleaning device and an operating method thereof. The disclosed root canal cleaning device comprises: a vibrator which generates a first acoustic wave; an ultrasonic horn which amplifies the first acoustic wave generated by the vibrator; an acoustic resonance unit which causes the first acoustic wave amplified by the ultrasonic horn to resonate and emits a second acoustic wave toward the root canal; and a liquid medium supply unit including an inlet through which is injected a liquid medium that transmits at least one of the first acoustic wave and the second acoustic wave to the root canal, and a first passage through which the liquid medium moves, wherein vapor bubbles are generated and collapse within a cleaning solution inside the root canal or within the liquid medium delivered to the vicinity thereof, together with the first acoustic wave or the second acoustic wave, thus enabling the removal of materials to be cleaned from inside a tooth, including the root canal.

Description

Root canal irrigation device and method of operation thereof

[0001] The present invention relates to dental treatment technology, and more specifically, to a root canal cleaning device and a method of operating the same.

[0002] A tooth is largely composed of the crown, which is exposed above the gums, and the root, which is located inside the gums; the pulp chamber is formed within the crown, and the root canal is formed within the root. The pulp chamber and the root canal form a continuous passageway through which nerves and blood vessels pass, and they are connected to the tissues surrounding the root apex through the apical foramen formed at the root apex.

[0003] Meanwhile, if bacteria penetrate the root canal due to causes such as infection, tooth decay, or trauma, the pulp tissue becomes inflamed or necrotic, and in severe cases, a periapical abscess forms. In such cases, a root canal therapy procedure is required to remove the damaged pulp tissue, clean and disinfect the inside of the root canal, and then fill it. Root canal cleaning is a core step in the root canal therapy process, and it is necessary to completely remove contaminants remaining inside the root canal, such as necrotic tissue, bacteria, biofilm, and smear layers.

[0004] Conventionally, to clean root canals, methods have been used in which a long, thin metal file or a polymer tip is directly inserted into the root canal to mechanically scrape it out, or in which ultrasonic vibrations are applied to generate flow in the cleaning solution.

[0005] However, conventionally, since instruments such as the aforementioned file or tip must be inserted directly into the root canal, it is difficult for the instrument to reach all parts of the root canal, which is severely curved or has a complex shape, so complete cleaning may not be achieved. In addition, the tip must have a thin and curved shape to be applied in the narrow space of the oral cavity; however, this structure has physical limitations in delivering high-output ultrasonic energy, which may weaken the cleaning power. Furthermore, there is a risk of medical accidents due to instrument fracture during treatment.

[0006] Recently, to overcome these limitations, a technology is being introduced that generates flow remotely for cleaning without directly inserting an instrument into the root canal. This technology uses ultrasonic or laser energy to induce acoustic cavitation in the cleaning solution inside the root canal, and achieves a cleaning effect through the mechanical action of the bubbles generated at that time.

[0007] The bubbles generated in the aforementioned acoustic cavitation are broadly classified into two types. One is a dissolved gas bubble, formed when air dissolved in a liquid is released due to a drop in pressure, and the other is a vapor bubble, which occurs as the liquid boils due to instantaneous low pressure. Among these, dissolved gas bubbles can be easily generated even at relatively low acoustic pressures, making them suitable for use in cleaning methods utilizing conventional files or tips. However, because dissolved gas bubbles have a long lifespan, they can remain within narrow and long root canals, forming a film of bubbles that can cause a phenomenon called "vapor lock." This bubble lock causes a serious problem by interfering with the propagation of ultrasonic energy, preventing cleaning power from reaching deep into the root canal. In contrast, vapor bubbles are generated and dissipate very quickly, so they do not cause bubble lock; furthermore, upon collapse, they generate a high-speed micro-jet, resulting in significantly superior cleaning power. Therefore, for ideal root canal cleaning, it is essential to suppress the formation of dissolved gas bubbles and induce the formation of vapor bubbles.

[0008] However, generating vapor bubbles requires ultrasound with very high acoustic pressure exceeding a specific threshold. As previously mentioned, conventional dental ultrasound devices, which are miniaturized and curved for intraoral application, have structural limitations in reliably generating and delivering such high-output ultrasound into the root canal.

[0009] Therefore, there is a need to develop a new type of high-power ultrasonic root canal cleaning technology that can provide powerful cleaning power to the entire root canal without air bubble blockage, without directly inserting instruments into the root canal.

[0010] The technical problem that the present invention aims to solve is to provide a root canal cleaning device and a method of operation thereof that can effectively clean the entire length of a root canal by transmitting high-power ultrasound to deep inside the root canal through a liquid medium without inserting instruments such as tips or files into the root canal, and by stably generating and controlling vapor bubbles through the liquid medium by the ultrasound.

[0011] Furthermore, the technical problem that the present invention aims to solve is to provide a root canal cleaning device and a method of operation thereof that simultaneously improve cleaning efficiency and oral applicability through the generation of high-power ultrasound.

[0012] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be understood by those skilled in the art from the description below.

[0013] According to one embodiment of the present invention, a root canal cleaning device may be provided, comprising: a vibrator that generates a first acoustic wave; a vibrating horn that amplifies the first acoustic wave generated from the vibrator; an acoustic resonator that resonates the first acoustic wave amplified from the vibrating horn and radiates a second acoustic wave in the direction of the root canal; and a liquid medium supply unit comprising an injection port that injects a liquid medium that transmits at least one of the first acoustic wave and the second acoustic wave in the direction of the root canal and a first passage through which the liquid medium travels.

[0014] The cleaning target inside the tooth, including the root canal, can be removed by generating and collapsing vapor bubbles within the liquid medium delivered into or near the root canal together with the first acoustic wave or the second acoustic wave.

[0015] The above-mentioned vibrating horn may include: an input end receiving the first acoustic wave from the vibrator; a vibrating shaft extending perpendicularly to the cross-section of the input end to amplify the first acoustic wave; and an output end having a cross-section that is parallel or not parallel to the cross-section of the input end and emitting the amplified first acoustic wave into the passage.

[0016] The cross-section of the output terminal above may be flat or have a curved surface.

[0017] In the case where the cross-section of the output end is a plane that is not parallel to the cross-section of the input end, the cross-section of the output end includes a cross-section inclined with respect to the axis of the vibration axis, and the output end can convert the propagation direction of the first acoustic wave into the direction of the root canal through the inclined cross-section and emit it.

[0018] When the cross-section of the output end has the inclined cross-section with respect to the axis of the vibration axis, the acoustic resonator is positioned opposite to the output end of the vibration horn, and can generate the second acoustic wave by resonating the first acoustic wave incident from the vibration horn.

[0019] The above acoustic resonance part may include an opening that discharges the liquid medium moving through the passage formed between the acoustic resonance part and the vibration horn to the outside of the root canal cleaning device, and a protrusion connected to the opening that forms a second passage so that the liquid medium is concentrated in the direction of the root canal.

[0020] The above vapor bubbles may collapse inside or near the root canal to generate shock waves and micro-jet flow.

[0021] The device further includes a handpiece housing that accommodates at least one of the above vibrator and the above vibrating horn, and the acoustic resonator may have its outer circumference fixed to the end portion of the handpiece housing.

[0022] The first acoustic wave or the second acoustic wave may include an acoustic wave having an ultrasonic frequency of 20 kHz or higher.

[0023] The natural resonant frequency of the above-mentioned vibrating horn and the above-mentioned acoustic resonator may be substantially the same.

[0024] According to another embodiment of the present invention, the method may include the steps of: generating a first acoustic wave by applying electrical energy to a vibrator; amplifying the first acoustic wave through a vibrating horn coupled to the output end of the vibrator; transmitting the amplified first acoustic wave through a liquid medium to an acoustic resonator spaced apart from the output end of the vibrating horn; inducing resonance in the acoustic resonator by the transmitted first acoustic wave to generate a second acoustic wave; generating a vapor bubble in the liquid medium according to pressure fluctuations of the second acoustic wave; and cleaning the inside or near the root canal with shock waves and micro-jet flow generated by the collapse of the vapor bubbles.

[0025] The method may further include the step of providing the liquid medium to a first passage formed between the outer wall of the vibration horn and the inner wall of the handpiece housing and a second passage formed between the output end of the vibration horn and the acoustic resonance part.

[0026] The step of transmitting the amplified first acoustic wave through a liquid medium to an acoustic resonator spaced apart from the output end of the vibrating horn may include the step of diverting the amplified first acoustic wave in the direction of the root canal through the output end of the vibrating horn.

[0027] The above acoustic resonance part can be tuned to resonate at a frequency substantially identical to the natural resonance frequency of the vibration horn.

[0028] The generation and collapse of the above vapor bubbles may occur repeatedly within the liquid medium or cleaning solution.

[0029] The step of cleaning the inside or near the root canal with shock waves and microjet flows generated by the collapse of the above-mentioned vapor bubbles may include the step of removing contaminants attached to the inner wall or inside of the root canal by the shock waves and microjet flows, and the step of discharging the removed contaminants and biofilms to the outside of the root canal together with the liquid medium or cleaning solution by using acoustic flow induced by the collapse of the above-mentioned vapor bubbles.

[0030] According to embodiments of the present invention, since ultrasonic waves are transmitted through a liquid medium to a cleaning solution inside a root canal through a vibrating horn and an acoustic resonator, a root canal cleaning device and a method of operation thereof that do not require inserting a tip or file into the root canal can be implemented.

[0031] In addition, since there is no need to insert tips or files into the root canal, the risk of instrument fracture and damage to the root canal wall can be eliminated.

[0032] In addition, a root canal cleaning device and a method of operation thereof can be implemented in which secondary ultrasound emitted from an acoustic resonance unit forms a continuous negative pressure field in the cleaning solution inside the root canal, and in the relaxation section, the local pressure is lowered below the vapor pressure to generate vapor bubbles, thereby perfectly cleaning the root canal.

[0033] It is possible to implement a root canal cleaning device and a method of operation thereof in which acoustic attenuation caused by dissolved gas bubbles is minimized, thereby increasing the ultrasonic energy transfer efficiency.

[0034] By combining a diagonal cut vibrating horn structure and a resonance plate, the overall structure of the device can be simplified and miniaturized. This allows for easy use even in limited spaces within the oral cavity, and enables the realization of an endodontic irrigation device and its method of operation that significantly improve clinical applicability.

[0035] The ultrasonic field forms a negative pressure of approximately 100 kPa or more, and local impact resulting from the generation and collapse of bubbles acts on the wall of the root canal, thereby enabling the implementation of a root canal cleaning device and a method of operation thereof that can effectively remove residual bacteria and contaminants throughout the entire area of ​​the root canal.

[0036] However, the effects of the present invention are not limited to the above effects and can be extended in various ways without departing from the technical concept and scope of the present invention.

[0037] FIGS. 1a and FIGS. 1b are diagrams showing the configuration of a root canal cleaning device according to an embodiment of the present invention.

[0038] FIG. 2 is a schematic diagram illustrating the basic pressure wave propagation characteristics of ultrasound according to an embodiment of the present invention.

[0039] Figure 3 is a phase change graph illustrating the principle of vapor bubble formation according to an embodiment of the present invention.

[0040] Figure 4 is a schematic diagram illustrating the dynamic behavior of a vapor bubble generated by ultrasound.

[0041] FIG. 5a is a drawing for explaining the structural features and operating principle of a straight ultrasonic horn according to an embodiment of the present invention, and FIG. 5b is a drawing for explaining the structural features and operating principle of an obliquely cut ultrasonic horn according to an embodiment of the present invention.

[0042] FIGS. 6a and FIGS. 6b are experimental observation images showing the cleaning effect according to the output of the acoustic resonance part according to an embodiment of the present invention.

[0043] Figures 7a and 7b are images of experimental results comparing the cleaning behavior of dissolved gas bubbles (comparative example) and steam bubbles (example) formed during ultrasonic cleaning inside a root canal.

[0044] Figures 8a and 8b are drawings comparing the cleaning effect of a model root canal with and without an acoustic resonance part.

[0045] FIG. 9 is a flowchart for explaining the operation method of a root canal cleaning device according to an embodiment of the present invention.

[0046] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0047] The embodiments of the present invention described below are provided to more clearly explain the present invention to those skilled in the art, and the scope of the present invention is not limited by the following embodiments, and the following embodiments may be modified in various other forms.

[0048] The terms used herein are for describing specific embodiments and are not intended to limit the invention. Terms used herein in the singular form may include plural forms unless the context clearly indicates otherwise. Additionally, the terms “comprise” and / or “comprising” used herein specify the presence of the mentioned features, steps, numbers, actions, components, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, steps, numbers, actions, components, elements, and / or groups thereof. Furthermore, the term “connected” used herein means not only that components are directly connected, but also includes the concept of indirectly connecting components through the interposition of additional components between them.

[0049] Furthermore, when a component is described in this specification as being located "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components. The term "and / or" as used in this specification includes any one of the listed items and all combinations of one or more thereof. Additionally, terms of degree such as "about" and "substantially" as used in this specification are used to mean a range of numerical values ​​or degrees or approximate values, taking into account inherent manufacturing and material tolerances, and are used to prevent an infringer from unfairly exploiting the disclosures in which precise or absolute figures provided to aid in understanding this specification are mentioned.

[0050] Embodiments of the present invention will be described in detail below with reference to the attached drawings. The sizes or thicknesses of the areas or parts depicted in the attached drawings may be slightly exaggerated for the clarity of the specification and convenience of explanation. Throughout the detailed description, the same reference numerals indicate the same components.

[0051] Hereinafter, in order to enable a person skilled in the art to easily practice the present invention, various preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0052]

[0053] FIGS. 1a and FIGS. 1b are diagrams showing the configuration of a root canal cleaning device according to an embodiment of the present invention.

[0054] Referring to FIGS. 1a and 1b, the root canal cleaning device (100) may include a vibrator (10), a vibrating horn (20), an acoustic resonator (30), a guide member (40), a liquid medium supply unit (50), and a handpiece housing (60) that accommodates the vibrator (10) and the vibrating horn (20). The root canal cleaning device (100) may further include a power supply unit (not shown), such as a battery. The handpiece housing for accommodating the vibrator (10) and the handpiece housing (60) for accommodating the vibrating horn (20) can be implemented as separate or integrated units. Components such as the vibrator (10), the vibrating horn (20), the acoustic resonator (30), and the guide member (40) can be fixedly connected to and detached from the handpiece housing (60), allowing for replacement. After cleaning treatment, it is hygienically desirable to remove components that have come into direct or indirect contact with the patient's oral cavity and replace them with new components for the next cleaning treatment.

[0055] The vibrator (10) can generate a first acoustic wave by converting electrical energy into mechanical vibration based on the inverse piezoelectric effect. The generated ultrasonic vibration can be transmitted to the vibrating horn (20). The vibrator (10) may include any one of a nickel vibrator, a ferrite vibrator, a piezoelectric ceramic vibrator, a BLT (Bolt-clamped Langevin Type) vibrator, or a quartz vibrator. Preferably, the vibrator (10) may be an ultrasonic vibrator having a BLT structure.

[0056] In one embodiment, the vibrator (10) has a structure in which piezoelectric ceramic elements are stacked in multiple layers, and when an alternating voltage having a frequency in the ultrasonic band higher than the audible frequency is applied to the piezoelectric ceramic elements, the (+) and (-) of the alternating voltage change rapidly, causing the piezoelectric ceramic elements to repeatedly expand and contract at a very high speed. This rapid expansion and contraction of the piezoelectric ceramic elements manifests as powerful mechanical vibrations. As a non-limiting example, the vibrator (10) may also operate with a direct current voltage, but it is preferable to drive it with an alternating current voltage. Additionally, it is possible to apply a signal modulated in the form of a pulse or a burst.

[0057] The purpose of using an ultrasonic transducer with a BLT structure is to achieve high ultrasonic output. To achieve high output, the diameter of the BLT transducer can range from approximately 5 mm to 50 mm. If the transducer diameter is reduced to less than 5 mm, the conversion efficiency of electrical energy into mechanical vibration drops sharply as the cross-sectional area of ​​the piezoelectric ceramic element decreases. Furthermore, the reduced cross-sectional area increases stress per unit area, which may lead to non-linear vibration within the transducer or increase thermal accumulation, thereby raising the risk of thermal fracture. Consequently, at diameters less than 5 mm, the resonance frequency becomes unstable during high-power operation, making it difficult to secure sufficient amplitude for ultrasonic cleaning. On the other hand, if the transducer diameter exceeds 50 mm, high-power operation is possible, but the increased volume and mass of the piezoelectric ceramic cause inconvenience for medical personnel. Additionally, as the transducer diameter increases, it may become difficult to apply it within the oral cavity. This can impair the directionality of the ultrasonic energy transmitted to the vibrating horn (20), thereby reducing the accuracy of acoustic refraction and the efficiency of cavitation. Preferably, the diameter of the BLT vibrator may be about 15 mm. It must be understood that the vibrator (10) in the present invention is not limited to a BLT vibrator, and any type of vibrator is within the scope of the present invention as long as it provides an ultrasonic output capable of generating a vapor bubble well in a liquid medium or cleaning solution.

[0058] The vibrating horn (20) can amplify the first acoustic wave generated from the vibrator (10). The vibrating horn (20) may include an input end (IT) that receives the first acoustic wave from the vibrator (10), a vibrating axis (VX) that extends perpendicularly to the cross-section of the input end (IT) to amplify the first acoustic wave, and an output end (OT) that has a cross-section that may or may not be parallel to the cross-section of the input end (IT) and emits the amplified first acoustic wave. Although FIGS. 1a and 1b show a case where the cross-section of the output end (OT) has a curved surface, the cross-section of the output end (OT) may have a surface parallel to the cross-section of the input end (IT) as shown in FIG. 5a, which will be described later.

[0059] In one embodiment, if the cross-section of the output end (OT) is a plane that is not parallel to the cross-section of the input end (IT), the cross-section of the output end (OT) includes a cross-section inclined with respect to the axis of the vibration axis, and the output end (OT) can divert the propagation direction of the first acoustic wave to the root canal (RC) direction and emit it through the inclined cross-section. The output end (OT) of the vibrating horn (20) has a cross-section inclined at an angle of 10° to 80° with respect to the axis. Preferably, the output end (OT) of the vibrating horn (20) may have a cross-section inclined at an angle of 30° to 60° with respect to the axis. The diameter of the vibrating horn (20) may range from 3 mm to 10 mm. The length of the vibrating horn (20) may be designed to be half the wavelength (λ) of the ultrasound or a multiple thereof. If the length of the vibrating horn is at the λ / 2 level, the length is too short, making it difficult to apply within the oral cavity. If the length of the vibrating horn is more than three times λ / 2, the volume and mass of the vibrating horn increase, which may exacerbate discomfort during oral application. Considering both the design conditions and usability of the vibrating horn, the length of the vibrating horn can preferably be designed to be similar to the wavelength of the ultrasound.

[0060] The present invention is not limited thereto, and the angle of the inclined cross-section and the diameter of the vibrating horn (20) may be set to maximize the output efficiency of the first acoustic wave transmitted from the output end (OT) of the vibrating horn (20) to the acoustic resonance part (30), and may also be determined by considering the convenience of the user during root canal cleaning work.

[0061] Additionally, the vibrating horn (20) has a structure in which the part connected to the vibrator (10) is wide and tapers toward the end, so that energy transmitted from a wide area is concentrated at the narrow end, thereby amplifying the ultrasonic output per unit area. The vibrating horn (20) can refract or change the direction of the first acoustic wave. The output end (OT) of the vibrating horn (20) of the present invention is cut diagonally so that it has a cross-section oblique to the axis. This diagonal structure induces asymmetrical vibration in the vibrating horn (20), causing the amplified first acoustic wave to be radiated in the direction of the cut cross-section (direction of the root canal of the tooth) rather than in the direction of the horn's axis. Through this, the acoustic wave can be efficiently transmitted to a target point without a separate direction-changing component.

[0062] The acoustic resonator (30) can resonate the first acoustic wave incident from the vibrating horn (20) and emit a second acoustic wave in the direction where the root canal (RC) is located. Additionally, the outer circumference of the acoustic resonator (30) can be fixed to the end portion of the handpiece housing (60). Specifically, the acoustic resonator (30) may include any one of a metal, a polymer, or a metal-polymer laminate. The shape, thickness, and material of the acoustic resonator (30) are designed to match the frequency characteristics of the first acoustic wave incident from the vibrating horn (20), and thereby the acoustic resonator (30) can be designed to respond to the first acoustic wave and generate a second acoustic wave of high sound pressure. In other words, by increasing the vibration displacement of the acoustic resonator (30) by the first acoustic wave, the sound pressure amplitude of the radiated second acoustic wave is increased, thereby forming stronger acoustic energy within the treatment area.

[0063] In one embodiment, when the cross-section of the output end (OT) of the vibration horn (20) has the inclined cross-section with respect to the axis of the vibration axis (VX), the acoustic resonance member (30) is positioned opposite to the output end (OT) of the vibration horn (20) so as to resonate the first acoustic wave incident from the vibration horn (20) to generate the second acoustic wave.

[0064] Here, the acoustic resonance part (30) may be composed of a base, an opening (OP) formed on the base to discharge a liquid medium (LM), and a protrusion connected to the opening (OP) to form a discharge passage so that the liquid medium (LM) is concentrated in the direction of the root canal (RC) together with the second acoustic wave. The outer circumference of the base may be configured to resonate by being fixed by the end portion of the handpiece housing (60), and the protrusion may be extended from the opening (OP) in the axial direction of the root canal (RC) so that its end is positioned to face the upper surface of the root canal (RC).

[0065] In one embodiment, the diameter (D2) of the opening (OP) is smaller than the diameter (D1) of the output end (OT) of the vibrating horn (20). The diameter (D1) of the output end (OT) is the surface on which the vibrating horn (20) radiates axial vibration; the larger this area, the greater the total energy radiated, but the lower the sound pressure per unit area. The diameter (D2) of the opening (OP) is the outlet where ultrasonic waves are concentrated as the liquid medium passes through; the smaller this hole, the more the energy is concentrated due to the nozzle effect, but if it is too small, fluid flow resistance and pressure reflection may occur.

[0066] Preferably, the diameter of the opening (OP) may range from 0.5 mm to 10 mm. If the diameter of the opening (OP) is less than 0.5 mm, the discharge flow rate of the liquid medium may be limited if the opening (OP) is excessively narrow, and acoustic waves passing through the opening may be diffusely reflected inside the opening, causing the sound pressure to be damped. If the diameter of the opening (OP) exceeds 10 mm, the radiated sound pressure may be dispersed over a wide area as the opening area increases, which may result in a lower acoustic energy density. Since acoustic waves must be concentrated in a narrow area, such as the pulp cavity or root canal, to efficiently clean the root canal, it is undesirable for the acoustic waves to be dispersed over a wide area. The sound pressure in the target area may be reduced, preventing it from exceeding the cavitation threshold. In summary, when the diameter of the opening (OP) is in the range of 0.5 to 10 mm, attenuation due to diffuse reflection of acoustic waves can be suppressed, and the effects of sound pressure concentration and cavitation induction are maximized.

[0067] The guide member (40) can be used as a support for mounting the root canal cleaning device (100) on the treatment tooth (TE) so that the acoustic resonance part (30) does not come into contact with the treatment tooth (TE). The guide member (40) can be fixed in conjunction with the handpiece housing (60) and, if necessary, can be detached from the handpiece housing (60) and replaced with another guide member. The detached guide member (40) can be cleaned separately to maintain hygienic cleanliness.

[0068] The distance between the acoustic resonance part (30) and the output end (OT) of the vibration horn (20) can be set to a range of about 0.5 mm to 20 mm. The first acoustic wave amplified in the vibration horn (20) can be transmitted to the acoustic resonance part (30) through a liquid medium (LM) to induce vibration of the acoustic resonance part (30). In order to transmit high-energy sound waves to the acoustic resonance part (30) without acoustic attenuation, the distance between the acoustic resonance part (30) and the output end (OT) of the vibration horn (20) can be set to a level of several mm. The outer circumference of the acoustic resonance part (30) is fixed to the end of the handpiece housing (60) and can vibrate by the first acoustic wave amplified in the vibration horn (20).

[0069] In one embodiment, ultrasonic vibrations generated in the acoustic resonator (30) are transmitted to the root canal through the liquid medium (LM), and vapor bubbles may be generated within the liquid medium (LM) filled in the root canal by pressure fluctuations caused by the second acoustic wave. The vapor bubbles may periodically expand and contract according to the pressure cycle of the second acoustic wave, and collapse near the inner wall of the root canal (RC) to generate shock waves and micro-jet flow, thereby cleaning and washing the root canal. The acoustic streaming induced by the vapor bubbles may be used to discharge contaminants and biofilms detached from the walls of the root canal to the outside of the root canal.

[0070] The liquid medium supply unit (50) may include an injection port (51) for injecting the liquid medium (LM) and a passage (52) through which the liquid medium (LM) travels. The passage (52) through which the liquid medium (LM) travels is formed to surround the vibrator (10) and the vibrating horn (20), and the liquid medium (LM) may be a cooling liquid and may reduce the heat generated in the vibrator (10) and the vibrating horn (20). Additionally, the liquid medium (LM) flowing through the passage (52) between the acoustic resonance unit (30) and the output end (OT) of the vibrating horn (20) may be discharged in the direction of the root canal through the opening (OP) of the acoustic resonance unit (30).

[0071] The outer wall of the vibrating horn (20) and the inner wall of the handpiece housing (60) form a first space, and the first space is connected to the injection port (51) to provide a path for the movement of the liquid medium (LM). Additionally, the end portion of the handpiece housing (60) is coupled to the outer circumference of the acoustic resonance unit (30), so that a second space is formed between the acoustic resonance unit (30) and the output end (OT) of the vibrating horn (20), and the second space is connected to the first space to provide a passage for the movement of the liquid medium (LM). A portion of the liquid medium (LM) in the second space may be discharged along with the acoustic waves through the opening (OP) of the acoustic resonance unit (30), and the discharged liquid medium (LM) may be guided toward the root canal (RC) and used as a cleaning solution.

[0072] Specifically, the discharged liquid medium (LM) is a medium that propagates the second acoustic wave generated in the acoustic resonance unit (30), and at this time, a cavitation phenomenon may occur in which vapor bubbles are generated, moved, and collapse within the root canal in the cleaning solution connected to the liquid medium. That is, in the present invention, the liquid medium (LM) mainly performs the role of a medium that transmits ultrasound to the root canal, and in addition, it may perform the role of cooling the vibrator (10) and the vibrating horn (200). Preferably, the liquid medium (LM) may be a degassed liquid.

[0073] In one embodiment, the first acoustic wave generated from the vibrator (10) and amplified through the vibrating horn (20) and the second acoustic wave generated by the acoustic resonator (30) may be ultrasonic sound waves having an ultrasonic frequency of 20 kHz or higher. Additionally, the resonance frequencies of the vibrating horn (20) and the acoustic resonator (30) may be similar or nearly identical.

[0074] In the present invention, the cleaning solution is connected to the liquid medium and can receive acoustic waves and perform the function of generating vapor bubbles inside the root canal.

[0075]

[0076] Referring again to FIG. 1b, if the acoustic resonance unit (30) is positioned near the entrance of the root canal, the distance over which the sound wave must propagate is shortened, thereby simultaneously reducing the sound pressure reduction due to geometric diffusion and the attenuation loss due to sound absorption by the medium. As a result, the effective sound pressure reaching the inside of the root canal increases. In addition, ultrasound may undergo phenomena such as reflection, refraction, and scattering due to housing walls, boundaries, and changes in the medium along the propagation path, and some energy may be dispersed or lost. However, in the present invention, by positioning the acoustic resonance unit (30) near the target for cleaning (e.g., the entrance of the root canal), the path through which the ultrasonic sound source is transmitted to the root canal is shortened, and interaction with walls or boundaries within the transmission path is reduced, thereby significantly mitigating such reflection, refraction, and scattering losses. That is, the transmission path of acoustic energy is simplified, and the proportion of energy preserved in the direction of the root canal is increased. This is a physical effect achieved simply by shortening the distance between the sound source and the target point, without the need for a separate directional design.

[0077]

[0078] FIG. 2 is a schematic diagram illustrating the basic pressure wave propagation characteristics of ultrasound according to an embodiment of the present invention. In the present invention, ultrasound refers to a sound wave having a frequency of at least the audible frequency (about 20 kHz) that humans can hear.

[0079] Referring to FIG. 2, the ultrasound can propagate in the form of a pressure wave in which compression and rerefaction are repeated along a medium such as air, liquid, or solid. Specifically, during the propagation process of the ultrasound, local pressure maximums and pressure minimums are continuously formed within the medium as particles of the medium are periodically compressed or expanded. These pressure oscillations are repeated periodically over time, and the interval in which compression and rerefaction are repeated once is called one cycle, and the distance between adjacent pressure maximums is called the wavelength. That is, the ultrasound is a longitudinal wave transmitted by the vibration of molecules within the medium, and as energy travels along the medium, the local density and pressure of the medium change alternately.

[0080] Due to such periodic oscillations of pressure, a low-pressure region may be instantaneously formed within the liquid medium or cleaning solution, and a vapor bubble may be generated as a portion of the cleaning solution vaporizes in the low-pressure region.

[0081] Subsequently, when transitioning to the compression zone, the local pressure rapidly increases, causing the aforementioned vapor bubbles to contract or collapse abruptly, which can generate strong shock waves and micro-jets. This repetitive phenomenon of bubble generation and cavitation can be utilized to physically remove contaminants, biofilm, and smear layers from the inner walls of the root canal.

[0082] Therefore, unlike cleaning by simple fluid flow, the ultrasonic cleaning method used in the present invention utilizes minute local pressure changes and cavitation according to the pressure cycle of ultrasound to deliver a cleaning effect even to the fine branches and curves of the root canal.

[0083] FIG. 3 is a phase change graph to explain the principle of vapor bubble formation according to an embodiment of the present invention. A substance in a liquid state has solid, liquid, and gas phases depending on the combination of pressure (P) and temperature (T).

[0084] Referring to Figure 3, when the pressure applied to a liquid at a constant temperature decreases, the intermolecular bonds within the liquid weaken, causing localized vaporization. That is, when the local pressure of the liquid becomes lower than the vapor pressure at that temperature, the liquid partially turns into a gas and forms bubbles.

[0085] This phenomenon is distinct from the boiling of a liquid due to a rise in temperature; it is cavitation, in which bubbles are generated due to a drop in pressure. In other words, boiling water caused by a rise in temperature is vaporization due to heat, whereas the bubbles formed by the instantaneous drop in pressure caused by ultrasound are vaporization caused by a decrease in pressure.

[0086] When the pressure of a liquid is locally lowered, there are two types of bubbles that may be formed. One is a vapor bubble. This vapor bubble is a bubble created by the vaporization of the liquid itself, and its interior is mainly filled with the vapor of the liquid. The other is a gas bubble. This dissolved gas bubble is a bubble mainly formed by dissolved gases, such as air, that were dissolved in the liquid. For example, the foam that forms when opening a carbonated beverage can be cited as an example of this dissolved gas bubble.

[0087] In the present invention, as the pressure within the cleaning solution temporarily decreases during the ultrasonic translucency phase, a local pressure region below the vapor pressure of the liquid is formed, and vapor bubbles can be generated in this region. That is, periodic pressure vibrations of the ultrasound cause a pressure change (△P) within the liquid, causing a portion of the liquid to vaporize into a vapor state and form fine bubbles.

[0088] Subsequently, when the process transitions to the compression phase, the surrounding pressure rises rapidly, causing the vapor bubbles to collapse. The shock waves and micro-jet flow generated during this collapse process can effectively remove contaminants such as biofilm and smear layers from the walls of the root canal.

[0089] Figure 4 is a schematic diagram illustrating the contraction and expansion behavior of a vapor cavitation bubble generated by ultrasound.

[0090] Referring to FIG. 4, when ultrasound propagates through a liquid medium or cleaning solution, the medium periodically repeats a compression phase and a rarefaction phase. Accordingly, the pressure inside the cleaning solution, which receives acoustic waves from the liquid medium, changes over time, and in response to this pressure change, the bubbles inside the cleaning solution continuously repeat expansion and contraction. Specifically, during the compression phase, the bubbles contract and become smaller in size, and during the rarefaction phase, the radius (R) of the bubbles expands and can become larger.

[0091] The pressure (P) of the ultrasound can be expressed as a function (P = f(t, x, y, z)) that changes according to time (t) and position (x, y, z). The present invention can effectively remove contaminants inside the root canal by utilizing complex and dynamic behaviors such as vibration, extinction, and movement of vapor bubbles generated by such ultrasound.

[0092]

[0093] FIG. 5a is a drawing for explaining the structural features and operating principle of a straight ultrasonic horn according to an embodiment of the present invention, and FIG. 5b is a drawing for explaining the structural features and operating principle of an obliquely cut ultrasonic horn according to an embodiment of the present invention.

[0094] Referring to FIG. 5a, the ultrasonic cleaning vibrating horn (20') is formed with a linear-axis structure, and ultrasonic energy can be transmitted in the same axial direction (D1) as the central axis (ax) of the ultrasonic transducer (10). Since acoustic energy is transmitted mainly only in the axial direction (ax) in such a structure, direct ultrasonic transmission may be difficult to the structure that is vertically inserted into the interior (C) of the tooth (TE), such as a root canal (RC).

[0095] Referring to FIG. 5b, by forming the front end of the vibrating horn (20) into a structure that is cut diagonally, ultrasonic energy can be refracted or diverted and radiated in a direction different from the central axis (ax) of the vibrating horn (20).

[0096] That is, by obliquely cutting the output end of the vibrating horn (20), the resulting ultrasonic energy generated on the surface of the vibrating horn (20) travels in the normal direction (D2) of the oblique cut surface. Due to this structural refraction effect, ultrasonic waves can be efficiently transmitted in the direction of the root canal (RC) (D2) without the need for additional reflectors or resonant waveguides.

[0097] As previously mentioned, a straight horn (20') like Fig. 5a transmits ultrasonic vibrations only in the axial direction (ax) of the horn, which does not align with the direction of the root canal, so a separate reflective structure or a curved tip is required to concentrate energy to the cleaning location inside the tooth (TE). In addition, the ultrasonic cleaning performance is non-uniform, and the cleaning range may be limited when the instrument is inserted.

[0098] On the other hand, the diagonal cutting horn of the present invention has an output end of the vibrating horn (20) cut in a diagonal shape so that ultrasonic energy can be refracted and transmitted in the direction (D2) where the root canal (RC) of the tooth (TE) is located, rather than in the axial direction (ax).

[0099] Therefore, acoustic waves can be radiated in the direction of the root canal (D2) without a complex reflection structure. In addition, resonance efficiency and energy concentration are improved, allowing the generation, movement, and collapse of vapor bubbles in the direction of the root canal to be maximized. The cavitation of the cleaning solution is extended, allowing the cleaning effect to reach deep inside the tooth.

[0100] As a result, using a diagonal cutting horn allows the ultrasound generated from the vibrator (20) to be directly transmitted in the direction of the root canal (D2), thereby inducing strong cavitation in the acoustic resonance part (30) and the cleaning solution (CW).

[0101]

[0102] The vibrating horn (20) amplifies the first acoustic wave received from the vibrator (10) and radiates ultrasound in the direction of the root canal through its output terminal (OT). Since the output terminal (OT) of the vibrating horn (20) has a structure that is cut diagonally with respect to the axis (ax), the direction of propagation of the ultrasound is changed so that it can be efficiently radiated over the entire surface of the acoustic resonance part (30).

[0103] The acoustic resonance part (30) receives a first acoustic wave incident from the vibrating horn (20) and resonates, at which time a second acoustic wave is generated across the entire surface of the acoustic resonance part (30). The second acoustic wave is discharged together with a liquid medium (LM) through the protrusion (32) of the acoustic resonance part (30) to transmit powerful acoustic energy in the direction of the root canal.

[0104] Therefore, in the present invention, by utilizing the resonance of the vibrating horn (20) and the acoustic resonance part (30), a much larger vibration amplitude and a higher acoustic energy density can be obtained than when using only a single vibrator. As a result, the generation of vapor bubbles inside the root canal is maximized, and the cleaning efficiency inside the root canal can be significantly improved.

[0105] Acoustic energy generated at the output terminal (OT) of the vibration horn (20) is transmitted to the entire or part of the acoustic resonance section (30), and the amplitude may be greatest near the center of the acoustic resonance section (30).

[0106] In this way, the larger the amplitude of the acoustic resonance part (30), the higher the acoustic energy can be transmitted through the liquid medium (LM) adjacent to the surface of the acoustic resonance part (30). Acoustic energy generated by the high amplitude of the acoustic resonance part is transmitted to the cleaning solution in the root canal, thereby improving cleaning performance. On the other hand, if the amplitude of the acoustic resonance part (30) is insufficient, an effective level of acoustic energy may not be transmitted to the root canal.

[0107] FIGS. 6a and FIGS. 6b are experimental observation images showing the cleaning effect according to the amplitude of the acoustic resonance part (30) according to an embodiment of the present invention.

[0108] Referring to Fig. 6a, in the [Cleaning O] section, the vibration displacement is high at the level of tens of μm, and it can be seen that a large number of vapor bubbles are generated in the cleaning solution, and micro-flow occurs due to the collapse of the vapor bubbles, thereby actively cleaning the surface. On the other hand, referring to Fig. 6b, in the [Cleaning X] section, the vibration displacement is at the level of 1 μm or less, so cavitation hardly occurs, and it can be confirmed that the cleaning effect is significantly reduced.

[0109]

[0110] Figures 7a and 7b are experimental result images comparing the cleaning behavior of dissolved gas bubbles and vapor bubbles formed during ultrasonic cleaning inside a root canal.

[0111] Referring to Fig. 7a, in the case where a non-degassed cleaning solution is used, it is observed that numerous dissolved gas bubbles remain inside the root canal even after approximately 1 minute has elapsed since the application of ultrasound. These bubbles are formed when air (gas) dissolved in the cleaning solution separates in the negative pressure region; because the bubbles rise slowly and have a long lifespan, they can stagnate in the center or on the walls of the root canal, causing vapor lock. As a result, the cleaning flow induced by ultrasound is not transmitted throughout the entire root canal, and beyond a certain depth, cavitation is suppressed, preventing sufficient cleaning.

[0112] Referring to Fig. 7b, in the case where a degassed liquid is used, almost no bubble blockage is observed inside the root canal even after the same amount of time following ultrasound application. This appears to be because dissolved gases in the cleaning solution are removed, causing bubbles to form and collapse mainly in the form of vapor bubbles over a short period of time. In other words, vapor bubbles rapidly expand and contract according to pressure cycles and have a very short lifespan, so they do not remain inside the root canal; instead, the shock waves and micro-jet flows generated upon the collapse of the bubbles effectively clean the walls of the root canal. Therefore, by using a degassed liquid to induce cavitation centered on vapor bubbles, the ultrasonic cleaning effect can be delivered to the apical region without bubble blockage.

[0113]

[0114] Figures 8a and 8b are diagrams comparing the cleaning effect of a model root canal with and without an acoustic resonator. The root canal cleaning device was operated with the same input power (approx. 20 W), and the sound pressure at the outlet of the root canal cleaning device was measured using a hydrophone. An acoustic pressure of approximately 200 kPa was measured at the outlet of the root canal cleaning device with an acoustic resonator, while an acoustic pressure of approximately 60 kPa was measured at the outlet of the root canal cleaning device without an acoustic resonator.

[0115] Referring to Fig. 8a, contaminants inside the artificial model root canal could be completely removed with only about 2 minutes of operation.

[0116] Referring to Fig. 8b, even after the same 2-minute cleaning, contaminants inside the artificial root canal were not removed, making cleaning impossible.

[0117]

[0118] As described above, the present invention increases the effective sound pressure of the cleaning device by about three times or more by applying an acoustic resonance unit (30) even under the same power conditions, shortens the cleaning time, and significantly improves the cleaning efficiency. This is because sound waves are focused and losses are reduced by the acoustic resonance structure, thereby improving both the energy efficiency and the actual cleaning performance of the cleaning device.

[0119]

[0120] FIG. 9 is a flowchart for explaining the operation method of a root canal cleaning device according to an embodiment of the present invention.

[0121] Referring to FIG. 9, the method of operation of a root canal cleaning device (100) may include the steps of: applying electrical energy to a vibrator (10) to generate a first acoustic wave (S100); amplifying the first acoustic wave through a vibrating horn (20) coupled to the output end of the vibrator (10) (S102); transmitting the amplified first acoustic wave through a liquid medium (LM) to an acoustic resonance unit (30) spaced apart from the output end (OT) of the vibrating horn (20) (S104); inducing resonance in the acoustic resonance unit (30) by the transmitted first acoustic wave to generate a second acoustic wave (S106); generating a vapor bubble in the cleaning liquid according to the pressure fluctuation of the second acoustic wave (S108); and cleaning the inside or near the root canal with a shock wave and a micro-jet flow generated by the collapse of the vapor bubble (S110).

[0122] The step (S108) of forming the vapor bubble may include forming a local low-pressure region in the liquid medium (LM) flowing out through the opening (OP) of the acoustic resonator (30) according to the pressure cycle of the second acoustic wave, and vaporizing the cleaning solution in the low-pressure region to generate a vapor bubble. The vapor bubble may collapse near the root canal wall to generate a shock wave and a micro-jet flow. The acoustic streaming of the cleaning solution induced by the behavior of the vapor bubble may discharge contaminants and biofilms removed from the root canal wall to the outside of the root canal.

[0123] In one embodiment, the step of providing a liquid medium (LM) to a first liquid medium passage (52) formed between the outer wall of the vibrating horn (20) and the inner wall of the handpiece housing (60) and a second liquid medium passage (52) formed between the output end (OT) of the vibrating horn (20) and the acoustic resonance part (30) may be further included.

[0124] In one embodiment, the step (S104) of transmitting the amplified first acoustic wave through a liquid medium (LM) to an acoustic resonator (30) spaced apart from the output end (OT) of the vibrating horn (20) may include the step of converting the amplified first acoustic wave into a root canal direction through the output end (OT) of the vibrating horn (20).

[0125] In one embodiment, the acoustic resonator (30) can be tuned to resonate at a frequency substantially the same as the natural resonant frequency of the vibrating horn (20).

[0126] The generation and collapse of the above vapor bubbles can occur repeatedly within the liquid medium (LM).

[0127] The step (S110) of cleaning the inside or near the root canal with shock waves and micro-jet flows generated by the collapse of the above-mentioned vapor bubbles may include the step of removing contaminants attached to the inner wall or inside of the root canal by the shock waves and micro-jet flows, and the step of discharging the removed contaminants and biofilms together with a liquid medium (LM) to the outside of the root canal (RC) using acoustic flow induced by the collapse of the above-mentioned vapor bubbles. In other words, the contaminants and the liquid medium (LM) delivered toward the root canal (RC) in the cleaning step (S110) may flow out through the gap between the treated tooth (TE) and the guide member (40) and be discharged to the outside.

[0128] This specification discloses preferred embodiments of the present invention. Although specific terms have been used, they are used merely in a general sense to facilitate the explanation of the technical content of the invention and to aid in understanding the invention, and are not intended to limit the scope of the invention. It is obvious to those skilled in the art that, in addition to the embodiments disclosed herein, other variations based on the technical concept of the present invention are possible. Those skilled in the art will understand that the root canal cleaning device and the method of operation thereof according to the embodiments described with reference to FIGS. 1a, 1b, and 9 can be variously substituted, changed, and modified within the scope of the technical concept of the present invention. Therefore, the scope of the invention should not be determined by the described embodiments but by the technical concept described in the claims.

[0129] The root canal cleaning device and the method of operation according to the present invention can be widely applied to the step of removing infected pulp and cleaning and disinfecting the inside of the root canal during root canal treatment in dental procedures. Since the device of the present invention can precisely control the spray pressure, flow direction, or vibration conditions of the cleaning solution, it can efficiently remove residual bacteria, organic debris, and cutting debris from inside the root canal. Accordingly, cleaning efficiency is improved compared to existing manual cleaning methods or simple sonic / ultrasonic cleaning methods, and damage to the root canal walls or external leakage of the cleaning solution can be minimized. Therefore, the root canal cleaning device of the present invention can be widely used in dental endodontic treatment equipment, small medical cleaning systems, dental education and procedural training equipment, etc., and has very high industrial applicability, particularly in the entire dental medical device industry requiring automated root canal cleaning, microfluidic control-based cleaning, or complex ultrasonic cleaning technologies. In addition, since the root canal cleaning method of the present invention can be applied to various cleaning device structures or control algorithms, it can be usefully utilized in the fields of precision dentistry, microsurgery, and biocompatible medical devices in the future.

Claims

1. A vibrator that generates a first acoustic wave; A vibrating horn that amplifies the first acoustic wave generated from the above vibrator; and An acoustic resonator that resonates by the first acoustic wave amplified from the above-mentioned vibrating horn and radiates a second acoustic wave in the direction of the root canal; and It includes a liquid medium supply unit comprising an injection port for injecting a liquid medium that transmits at least one of the first acoustic wave and the second acoustic wave into a root canal, and a first passage through which the liquid medium travels. A root canal cleaning device that removes objects to be cleaned inside the tooth, including the root canal, by generating and collapsing vapor bubbles within the cleaning solution inside the root canal or the liquid medium delivered nearby together with the first acoustic wave or the second acoustic wave.

2. In Paragraph 1, The above-mentioned vibrating horn is, An input terminal receiving the first acoustic wave from the above vibrator; A vibration shaft extending perpendicularly to the cross-section of the input terminal to amplify the first acoustic wave; and A root canal cleaning device comprising an output end having a cross-section that is parallel or not parallel to the cross-section of the input end and emitting the amplified first acoustic wave into the first passage.

3. In Paragraph 2, A root canal cleaning device having a cross-section of the output end that is flat or curved.

4. In Paragraph 3, If the cross-section of the output end is a plane that is not parallel to the cross-section of the input end, the cross-section of the output end includes a cross-section inclined with respect to the axis of the vibration axis, and The above output terminal is a root canal cleaning device that converts the propagation direction of the first acoustic wave into the direction of the root canal and emits it through the above inclined cross-section.

5. In Paragraph 4, A root canal cleaning device in which, when the cross-section of the output end has the inclined cross-section with respect to the axis of the vibration axis, the acoustic resonator is positioned opposite to the output end of the vibration horn to resonate the first acoustic wave incident from the vibration horn and generate the second acoustic wave.

6. In Paragraph 1, The above acoustic resonance part is a root canal cleaning device comprising an opening that allows the liquid medium moving through the passage formed between the acoustic resonance part and the vibration horn to flow out to the outside of the root canal cleaning device.

7. In Paragraph 6, A root canal cleaning device comprising: the above acoustic resonance part further including a protrusion connected to the opening to form a second passage so that the liquid medium is concentrated in the direction of the root canal.

8. In Paragraph 1, A root canal cleaning device in which the above-mentioned steam bubbles collapse inside or near the root canal to generate shock waves and micro-jet flow.

9. In Paragraph 1 It further includes a handpiece housing that accommodates at least one of the above vibrator and the above vibrating horn, and The above acoustic resonance part is a root canal cleaning device in which the outer circumference is fixed to the end of the handpiece housing.

10. In Paragraph 1, A root canal cleaning device comprising the first acoustic wave or the second acoustic wave having an ultrasonic frequency of 20 kHz or higher.

11. In Paragraph 1, A root canal cleaning device in which the natural resonance frequency of the above-mentioned vibrating horn and the above-mentioned acoustic resonance part is substantially the same.

12. In Paragraph 1, The above liquid medium is a degassed liquid, and the root canal cleaning device.

13. A step of generating a first acoustic wave by applying electrical energy to a vibrator; A step of amplifying the first acoustic wave through a vibrating horn coupled to the output end of the vibrator; A step of transmitting the amplified first acoustic wave through a liquid medium to an acoustic resonator spaced apart from the output end of the vibration horn; A step of inducing resonance by the transmitted first acoustic wave in the acoustic resonance section to generate a second acoustic wave; A step of generating a vapor bubble in the liquid medium according to the pressure fluctuation of the second acoustic wave; and A method of operation of a root canal cleaning device comprising the step of cleaning the inside or near the root canal with shock waves and micro-jet flow generated by the collapse of the above-mentioned steam bubbles.

14. In Paragraph 13, A method of operating a root canal cleaning device further comprising the step of providing the liquid medium to a first passage formed between the outer wall of the vibrating horn and the inner wall of the handpiece housing and a second passage formed between the output end of the vibrating horn and the acoustic resonance part.

15. In Paragraph 13, The step of transmitting the amplified first acoustic wave through a liquid medium to an acoustic resonator spaced apart from the output end of the vibration horn is: A method of operating a root canal cleaning device comprising the step of converting the amplified first acoustic wave into the direction of the root canal through the output end of the above-mentioned vibrating horn.

16. In Paragraph 13, A method of operation of a root canal cleaning device in which the above acoustic resonance part is tuned to resonate at a frequency substantially identical to the natural resonance frequency of the above vibrating horn.

17. In Paragraph 13, The above method of operation of a root canal cleaning device in which the generation and collapse of the above vapor bubbles occur repeatedly within the above liquid medium.

18. In Paragraph 12, The step of cleaning the inside or near the root canal with shock waves and micro-jet flows generated by the collapse of the above-mentioned steam bubbles is, A method of operating a root canal cleaning device comprising the step of removing contaminants attached to the inner wall or inside of the root canal by means of the shock wave and micro-jet flow.

19. In Paragraph 28, A method of operating a root canal cleaning device comprising the step of discharging the removed contaminants and biofilm together with the liquid medium to the outside of the root canal by utilizing acoustic flow induced by the collapse of the above vapor bubbles.

Images