Root canal cleaning device

Abstract

A root canal irrigation device according to one embodiment of the present invention includes a sound pressure generator that operates upon application of power; a handpiece housing that accommodates the sound pressure generator; a cooling water passage formed inside the handpiece housing; a cooling water inlet formed in the handpiece housing and communicating with the cooling water passage; and an irrigation liquid nozzle installed in the handpiece housing. The ultrasonic sound pressure applied to the cooling water by the sound pressure generator is transmitted to the irrigation liquid, which generates steam bubbles in the irrigation liquid. The steam bubbles, along with the irrigation liquid, act on the tooth to be treated, removing material from the inside of the tooth, including the root canal. The irrigation liquid is a degassed liquid.

Description

[Technical Field]

[0001] The present invention relates to a root canal irrigation device. [Background technology]

[0002] In 1967, Kakeyash et al. first demonstrated in germ-free rats that bacteria are the main cause of pulpitis. Since then, it has become clear that the main causes of inflammatory reactions are biofilms, which are colonies of bacteria inside the root canal, and necrotic tissue. For successful nerve treatment, it is essential to completely remove the bacteria and necrotic tissue present in the root canal.

[0003] The root canal treatment process is roughly divided into three steps: root canal preparation, root canal irrigation, and root canal filling. The present invention relates to an apparatus used for the second of these steps, root canal irrigation.

[0004] Root canal irrigation is performed after the primary removal of rotten nerves using an endo file, and is essential for removing infectious microorganisms, making it an important process that greatly influences the success of nerve treatment.

[0005] Among conventional root canal cleaning devices, there is known a PUI (passive ultrasonic irrigation) device, which fills the root canal of a tooth with cleaning fluid, inserts a tip that emits ultrasonic waves, and cleans the root canal. However, this device requires the root canal to be widened in order to insert the tip into the root canal, and has the problem that it is difficult to insert the tip in root canals that are severely curved.

[0006] In addition to the above-described conventional root canal irrigation devices, the present inventors reviewed numerous patents and papers by leading researchers in the field of root canal irrigation devices before arriving at the present invention. Among these, we will introduce the technologies of U.S. Patent No. 8,753,121 B2 (hereinafter referred to as the "'121 Patent") and U.S. Patent No. 10,420,630 B2 (hereinafter referred to as the "'630 Patent"), both of which are issued by Sonendo, Inc. Unlike the PUI device described above, the technologies of Sonendo's U.S. patents are characterized by the fact that the irrigation device does not need to be directly inserted into the root canal during root canal irrigation. This has the advantage of eliminating problems such as tip breakage and enabling simultaneous irrigation of multiple root canals in a single procedure. These advantageous effects over conventional PUI devices are achieved not only by the technologies of Sonendo's U.S. patents described above, but also by the present invention.

[0007] First, a representative drawing of the '121 patent is attached hereto as Figure 1. The primary feature of this U.S. patent is the use of a liquid jet, a irrigation fluid sprayed at extremely high speed and pressure, to irrigate root canals. According to the specification, a liquid jet refers to a high-speed, high-pressure fluid sprayed by a high-pressure pump system. The liquid jet, designated by reference numeral 60 in Figure 1 and shown striking the inner surface of the tooth in a straight line, is the liquid jet. According to the specification, the liquid jet must meet the following conditions: a pressure of 7,000 psi (approximately 48,263 kPa) or more and a velocity of 50 m / s or more. The reasons for using such a high-speed, high-pressure liquid jet are two-fold: 1) to generate vapor bubbles; and 2) to generate acoustic waves during the process of the liquid jet colliding with the dentin, the hard tissue inside the tooth. The vapor bubbles and acoustic waves facilitate the separation of biofilm and / or necrotic tissue, which are targeted for removal during root canal irrigation. However, conventional liquid jet technologies suffer from problems due to the high speed and pressure of the liquid jet. Because the liquid jet has extremely high speed and pressure, it poses a safety hazard when directed directly into the root canal. While directing the liquid jet directly into the root canal poses a safety hazard, contact with other soft tissues in the oral cavity poses an even greater safety hazard. Therefore, in this technology, as shown in Figure 1, the liquid jet must be reflected off the hard dentin tissue in the tooth wall, and the reflected irrigation liquid is then introduced into the root canal. When performing root canal irrigation using this technology, it is difficult to accurately aim the liquid jet, which can be a burden for less skilled practitioners. Therefore, in order to use the liquid jet disclosed in Sonnendo's '121 patent for irrigation treatment, an additional structure is required to address the safety issues. We will consider the '630 patent, an improved version of the '121 patent, as a patent related to such a structure. A representative drawing of the '630 patent is attached as Figure 2.

[0008] As shown in Figure 2, in the '630 patent, the liquid jet 60 is guided along a guide tube designated by reference numeral 100, and finally impinges on a terminal component designated as an impingement member (designated by reference numeral 110), after which an expanding water column is introduced into the root canal. The reason for taking such measures is described in the specification of the '630 patent as follows:

[0009] “Embodiments of the guide tube 100 which include an impingement member 110 may reduce or prevent possible damage that may be caused by the jet during certain dental treatments.For example, use of the impingement member 110 may reduce the likelihood that the jet may undesirably cut tissue or propagate into the root canal spaces 30(which may undesirably pressurize the canal spaces in some cases).”

[0010] The above-cited portion of the '630 patent describes the problems that arise from the use of liquid jets, namely, patient damage, and explains the function of the impingement member 110, a component introduced to solve the problems of cutting tissue or increasing pressure inside the root canal to a level that poses a safety hazard. This impingement member 110 is the core of the '630 patent.

[0011] The inventors have identified the following problems with the prior art irrigation devices cited in the above-mentioned Sonnendo patents. First, a special high-pressure pump must be used to generate the high-velocity, high-pressure fluid referred to in the patents. Furthermore, the durability of not only the high-pressure generating unit such as the pump, but also the fluid passages, such as the fluid tubes through which such high-pressure fluid flows, must be managed at a special level. Furthermore, additional components, such as the impingement member introduced in the '603 patent, are required. This ultimately complicates the structure of the equipment used for irrigation treatment and increases the production costs of the equipment. Furthermore, the use of a high-velocity, high-pressure liquid jet does not fundamentally resolve the safety issues mentioned above, namely, the risk of cutting tissue in the patient's oral cavity or excessively high pressure in the root canal.

[0012] After recognizing these problems, the inventors realized the need to develop a device that can maximize cleaning efficiency while using a relatively slower speed and lower pressure cleaning solution than the high speed and high pressure cleaning solution used in the above-mentioned U.S. registered patent. As a result of their extensive research and development efforts, they have completed this invention. Summary of the Invention [Problem to be solved by the invention]

[0013] To provide a cleaning device that does not require root canal expansion when performing root canal cleaning treatment, can easily clean even severely curved root canals, can perform cleaning without directly inserting the cleaning device into the root canal, and can simultaneously clean multiple root canals in one treatment without causing the problem of tip breakage.

[0014] Another object of the present invention is to provide an irrigation device that can maximize the cleaning effect while spraying the irrigation liquid at a low speed and pressure compared to conventional technologies that use a high-speed, high-pressure liquid jet for root canal irrigation.

[0015] Another object of the present invention is to provide a cleaning device including an ultrasonic vibration structure that can spray cleaning liquid at low speed and low pressure and effectively generate steam bubbles even in an environment where a degassed liquid is used as the cleaning liquid (since the term "degassed liquid" is commonly used in the industry, hereinafter the English term "degassed liquid" will be used together with the Japanese term or will be used alone).

[0016] Another object of the present invention is to provide a cleaning device having a structure that can easily transmit ultrasonic vibrations to the inside of the teeth.

[0017] Another object of the present invention is to provide a cleaning device that can prevent gas bubbles, which cannot be completely prevented from occurring even when a degassed liquid is used, from blocking the root canal passage. [Means for solving the problem]

[0018] A root canal irrigation device according to one embodiment of the present invention includes a sound pressure generator that operates upon application of power; a handpiece housing that accommodates the sound pressure generator; a cooling water passage formed inside the handpiece housing; a cooling water inlet formed in the handpiece housing and communicating with the cooling water passage; and an irrigation liquid nozzle installed in the handpiece housing. The ultrasonic sound pressure applied to the cooling water by the sound pressure generator is transmitted to the irrigation liquid, which generates steam bubbles in the irrigation liquid. The steam bubbles, together with the irrigation liquid, act on the tooth to be treated and remove material from the inside of the tooth, including the root canal. The irrigation liquid is a degassed liquid.

[0019] The cooling water cools the sound pressure generating device, and degassed liquid may also be used as the cooling water.

[0020] The sound pressure generating device includes a vibrator that vibrates when power is applied, and a vibrating horn that is connected to the vibrator and vibrates, and that extends linearly.

[0021] The jet flow formed in the root canal by the irrigation nozzle expels gas bubbles blocking the root canal passage and / or contaminants detached from the root canal to the outside of the root canal.

[0022] The handpiece housing has a bent end, and an acoustic reflector is installed at the bent end, so that ultrasonic waves applied to the cooling water by the vibration horn are reflected by the acoustic reflector.

[0023] The acoustic reflector is disposed at a predetermined angle with respect to the cross section of the vibration horn.

[0024] An air bubble collecting space is formed on the upper surface of the handpiece housing, and air bubbles that gather around the acoustic reflector rise to the air bubble collecting space due to buoyancy and are collected.

[0025] The length of the irrigation nozzle may be set to spray irrigation fluid into the access cavity of a tooth during root canal irrigation.

[0026] In addition, additional components may be included in the cleaning device according to the present invention. [Effects of the Invention]

[0027] According to the present invention, when performing root canal cleaning treatment, root canal expansion is not required, cleaning can be easily performed even in the case of a severely curved root canal, and cleaning can be performed without directly inserting the cleaning device into the root canal, so there is no problem of tip breakage, and a cleaning device is provided that can simultaneously clean multiple root canals in one treatment.

[0028] In addition, the present invention provides an irrigation device that can maximize irrigation efficiency by spraying irrigation liquid at a low speed and pressure compared to conventional techniques that use a high-speed, high-pressure liquid jet for root canal irrigation.

[0029] In addition, the present invention provides a cleaning device including an ultrasonic vibration structure that can spray cleaning liquid at low speed and low pressure and effectively generate vapor bubbles even in an environment where a degassed liquid is used as the cleaning liquid.

[0030] Furthermore, the present invention provides a cleaning device having a structure that can easily transmit ultrasonic vibrations to the inside of the teeth.

[0031] Furthermore, the present invention provides a cleaning device that can prevent gas bubbles, which cannot be completely prevented from being generated even when degassed liquid is used, from blocking the root canal passage. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a representative drawing of a prior art U.S. patent ('121 patent) described in the background art section.

[0033] [Figure 2] 1 is a representative drawing of a prior art U.S. patent ('630 patent) described in the background art section.

[0034] [Figure 3] 1 is a table summarizing the differences in the characteristics of gas bubbles and steam bubbles that have become apparent from the research results of the present inventors.

[0035] [Figure 4] 1 is a photograph of a conventional dental cleaning device.

[0036] [Figure 5] 10 is a photograph showing a state in which a vibrator and a vibration horn of a prototype of a cleaning device according to an embodiment of the present invention are combined together.

[0037] [Figure 6] 4 is a diagram for schematically explaining the function of an acoustic reflector used in a cleaning device according to an embodiment of the present invention;

[0038] [Figure 7] 1A and 1B are diagrams for explaining the principle of ultrasonic wave transmission by an acoustic reflector.

[0039] [Figure 8] FIG. 10 is a diagram showing how the vibration direction is changed by the acoustic reflector and how the vibration reaches the teeth.

[0040] [Figure 9] 10A and 10B are diagrams relating to an experiment for performance verification of an acoustic reflector through ultrasonic output measurement.

[0041] [Figure 10] 1 is a diagram showing the overall structure of a cleaning device 10 according to an embodiment of the present invention.

[0042] [Figure 11] FIG. 1 is a diagram showing the function of steam bubbles and nozzles in root canal irrigation.

[0043] [Figure 12] This photograph shows gas bubbles blocking the model root canal and preventing cleaning.

[0044] [Figure 13] FIG. 10 is a diagram showing an experiment to evaluate the stability of root-end outflow from a nozzle 7 used in a cleaning device according to an embodiment of the present invention.

[0045] [Figure 14] 10A and 10B are diagrams illustrating a state in which air bubbles are trapped in a space provided in a handpiece housing of a cleaning device according to an embodiment of the present invention.

[0046] [Figure 15] 10 is a photograph showing the results of cleaning a model root canal using a prototype of a cleaning device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] The following detailed description of the present invention refers to the accompanying drawings, which show, by way of example, specific embodiments in which the present invention may be practiced. These embodiments are described in detail to enable those skilled in the art to fully practice the present invention. It should be understood that the various embodiments of the present invention, although different from one another, are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be embodied in different embodiments without departing from the spirit and scope of the present invention. It should also be understood that the location or arrangement of individual components within each embodiment may be changed without departing from the spirit and scope of the present invention. Therefore, the following detailed description should not be taken in a limiting sense, and the scope of the present invention should be understood to encompass the scope of the appended claims and all equivalents thereof.

[0048] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, a number of preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the present invention.

[0049]

[0050] <Gas and steam bubbles>

[0051] Figure 3 is a table summarizing the differences in the characteristics of gas bubbles and steam bubbles revealed by the inventors' research. As summarized in the table in Figure 3, gas bubbles and steam bubbles differ in their characteristics. Gas bubbles have a long lifespan and are generated simultaneously. Individual gas bubbles move along the surface and clean particles with relatively weak force in a narrow area around the bubble. On the other hand, steam bubbles have a relatively short lifespan but exhibit strong movement during their lifespan, thereby cleaning with relatively strong force in a wide area at one point. Although both types of bubbles exhibit different characteristics have the effect of promoting cleaning, the inventors focused on generating only steam bubbles. The first reason for this is the recognition of the fatal drawback of gas bubbles in root canal cleaning. The inventors' research results revealed that gas bubbles cause clogging in narrow and long root canals, and that unless this clogging phenomenon is resolved, it is impossible to clean narrow and thin root canals well to the end. The second reason is that steam bubbles have a higher movement intensity than gas bubbles, resulting in better cleaning performance.

[0052] Since the goal is to generate only vapor bubbles in the cleaning solution, it is natural that a degassed liquid must be used as the cleaning solution. If a liquid that does not remove gas is used as the cleaning solution, the generation of gas bubbles cannot be prevented. Even when a degassed liquid is used as the cleaning solution, the generation of gas bubbles cannot be completely prevented, and therefore, the phenomenon of intermittent gas bubbles blocking the root canal must be addressed, which will be discussed later. In order to generate vapor bubbles using a degassed liquid as the cleaning solution, a high acoustic pressure above a certain critical value must be applied to the cleaning solution, as summarized in the table in Figure 3. The configuration devised by the inventors to apply high acoustic pressure to the cleaning solution will be explained in the next section.

[0053]

[0054] <Necessity of a powerful ultrasonic wave applicator>

[0055] To generate steam bubbles, the output (or ultrasonic sound pressure) of the ultrasonic applicator must be high. To achieve high ultrasonic output, the cross-sectional area of ​​not only the ultrasonic vibrator but also the vibration application parts (scaler tips, files, vibrating horns, etc.) connected to the vibrator must be above a certain level, and it is advantageous for them to be linear. Existing dental cleaning devices use thin, curved parts (scaler tips or files, etc.) for application to the oral cavity, which makes it difficult to utilize high ultrasonic output.

[0056] The inventors selected a BLT-type transducer and devised a method of combining a linear vibration horn with the transducer. BLT stands for Bolt-clamped Langevin Transducer. The BLT-type transducer is one of various types of transducers commercially available at the time of the completion of this invention, including nickel transducers, ferrite transducers, piezoelectric ceramic transducers, BLT transducers, and quartz transducers. The purpose of using the BLT-type transducer is to achieve high ultrasonic output. To achieve high output, the diameter of the BLT transducer was determined to be relatively large, approximately 30 mm. Although the inventors selected and used the BLT-type transducer from various types of transducers, this does not mean that the transducer used in this invention is limited to the BLT-type transducer. It should be understood that any type of transducer falls within the scope of the present invention as long as it provides an ultrasonic output sufficient to generate steam bubbles in the degassed liquid.

[0057] Another important component besides the vibrator is the vibration transmission element, which is coupled to the vibrator and transmits the vibrations generated by the vibrator to the fluid medium (cooling water and irrigation liquid). In this embodiment, a vibrating horn is used as the vibration transmission element for transmitting the ultrasound generated by the BLT vibrator into the oral cavity via the fluid medium. While a vibrating horn is used as the vibration transmission element in this embodiment, it should be understood that vibration transmission elements of other structures or shapes may be used. To minimize the power loss of the ultrasound applied by the BLT vibrator, it is advantageous to use a linear vibrating horn. Since the cleaning device according to the present invention is inserted into the patient's oral cavity during operation, the volume of the vibrating horn is limited. However, if the volume of the vibrating horn is too small, the loss of ultrasound power will occur and steam bubbles will not be effectively generated in the degassed liquid. Therefore, the inventors devised a linear vibrating horn. The inventors ultimately selected a linear vibrating horn with a cross-sectional diameter of approximately 8 mm to be coupled with a BLT-type vibrator and fabricated a prototype. Furthermore, these prototypes were actually applied to verify their cleaning performance.

[0058] Ultrasonic wave applicators have been used in dental cleaning equipment before the present invention. Figure 4 is a photograph of a conventional dental cleaning device. In comparison, Figure 5 is a photograph of the combined vibrator and vibration horn of a prototype cleaning device according to an embodiment of the present invention. Comparing Figures 4 and 5, the difference between the vibration applicator component (thin tip or file) of a conventional dental cleaning device that uses ultrasonic waves and the vibration applicator component (vibration horn) of the device according to the present invention is clearly apparent. The conventional dental cleaning device shown in Figure 4 was almost unable to generate an ultrasonic output sufficient to generate steam bubbles in degassed liquid. The inventors of the two prior art cited in the background section of this specification, namely, the '121 patent and the '630 patent by Sonnendo, Inc., recognized that it was difficult to generate steam bubbles in degassed liquid using an ultrasonic vibration generator due to the physical limitations of the size of the dental treatment device inserted into the patient's mouth, and therefore resorted to a method of generating steam bubbles using a high-speed, high-pressure liquid jet.

[0059]

[0060] <Acoustic reflector for introducing powerful ultrasound into the oral cavity>

[0061] FIG. 6 is a diagram for schematically explaining the function of an acoustic reflector used in an irrigation device according to an embodiment of the present invention. A problem occurs when inserting the ultrasonic transducer shown in FIG. 5 and the vibration horn connected thereto into a patient's oral cavity. The use of a linear vibration horn increases the length of the irrigation device. Therefore, the need for an additional component to transmit ultrasonic vibrations generated by the vibration horn to the teeth arose. The inventors solved this problem by incorporating the acoustic reflector shown in FIG. 6 into an irrigation device according to an embodiment of the present invention. The acoustic reflector was introduced to facilitate the positioning of an irrigation device including a linear ultrasonic applicator in the oral cavity. By using the acoustic reflector, high-power ultrasonic waves can be applied directly to the root canal cavity and root canal of a tooth. Ultrasonic waves exhibit rectilinear propagation characteristics, and the acoustic reflector functions to change the direction of propagation of the rectilinear ultrasonic waves.

[0062] Figure 7 is a diagram illustrating the principle of ultrasonic wave transmission by an acoustic reflector. Ultrasonic waves applied by a vibration horn generate pressure waves as they propagate through a medium (cooling water in this case). At this time, the ultrasonic waves propagate in a direction perpendicular to the cross section of the vibration horn (linear propagation of ultrasonic waves). Ultrasonic waves have the characteristic of being reflected when they encounter another medium with a significantly different acoustic impedance (the product of the density and the sound propagation speed in each medium). At this time, the propagation direction of the reflected ultrasonic waves follows the principles of the angle of incidence and angle of reflection of the wave.

[0063] FIG. 8 is a diagram showing how the vibration direction is changed by the acoustic reflector and how the vibration reaches the teeth. As shown in FIG. 8, the acoustic reflector included in the cleaning device according to an embodiment of the present invention is preferably disposed at a 45-degree angle with respect to the cross section of the ultrasonic vibration horn. Any common solid material can be used as the material of the acoustic reflector. However, the greater the difference in acoustic impedance between the material and the liquid, the better the reflection efficiency. In this regard, it is preferable to use glass or metal materials rather than plastic materials. Although FIG. 8 shows the acoustic reflector as a flat plate, the acoustic reflector may have any shape other than a flat plate that can reflect ultrasonic waves.

[0064] FIG. 19 shows an experiment for verifying the performance of an acoustic reflector through ultrasonic output measurement. The inventors conducted the experiment shown in FIG. 9 to verify the performance of the acoustic reflector. The inventors measured the ultrasonic sound pressure applied by a vibrating horn using a hydrophone under both conditions, with and without an acoustic reflector, and compared the results. The results of this experiment confirmed that ultrasonic waves are transmitted well even with an acoustic reflector. However, some loss of output (sound pressure) was observed due to reflection through the acoustic reflector. As summarized in the table on the right side of FIG. 9, the ultrasonic output reflected through the acoustic reflector was measured to be approximately 150 kPa to 220 kPa. This level of output was found to be sufficient for generating vapor bubbles in the degassed cleaning liquid.

[0065]

[0066] <Overall structure of a cleaning device according to an embodiment of the present invention>

[0067] The overall structure of an irrigation device 10 according to one embodiment of the present invention will be described with reference to FIG. 10. The irrigation device 10 is a sound pressure generating device that vibrates when power is applied. It includes a vibrator 1 and a linear vibrating horn 2 connected to the vibrator 1. Here, "connected" refers to a direct connection or an indirect connection via another vibration transmission medium. Here, "linear" refers to an overall linear shape. Even if a part has a curved or slightly warped portion, it can be considered a linear shape as long as it is an overall linear shape, i.e., a shape that extends longitudinally. Both the vibrator 1 and the vibrating horn 2 are housed in a handpiece housing 3. The handpiece housing for housing the vibrator 1 and the handpiece housing for housing the vibrating horn 2 can be implemented as separate or integrated. Additional advantages can be achieved if the handpiece housing 3 housing the vibrator 1 is separable from the remaining parts. After irrigation treatment, it is preferable to remove the part that has been in direct or indirect contact with the patient's oral cavity and replace it with a new handpiece device for the next irrigation treatment for hygienic reasons. Replacing the parts including the vibrator 1 and the vibrating horn 2 is costly. As can be seen from Figure 10, the vibrator 1 is located at the farthest part of the entire handpiece device that comes into contact with the patient's oral cavity, without coming into contact with the cooling water A and irrigation solution B that have been applied to the patient's oral cavity. If the handpiece housing 3 is manufactured as a separate type so that the handpiece housing 3 that houses the vibrator 1 can be separated from the rest of the device, it is possible to replace only the rest of the device connected to the handpiece housing 3 that houses the vibrator 1, without replacing the handpiece housing 3 that houses the vibrator 1, which is advantageous in reducing costs.

[0068] The handpiece housing 3 is bent at 90 degrees toward the outlet. The acoustic reflector 4 is installed at this bent portion. A suitable installation angle is 45 degrees with respect to the cross section of the vibration horn. The acoustic reflector 4 installed in this manner reflects ultrasonic waves before transmitting them to the tooth to be treated. The function, principle, and ultrasonic reflection effect of the acoustic reflector 4 have been described in detail in previous sections of this specification.

[0069] A passage for cooling water A (shown in blue in FIG. 11 ) is formed inside the handpiece housing 3. The handpiece housing 3 is formed with a cooling water inlet 5, which communicates with the interior space of the handpiece housing, i.e., the cooling water passage. A cooling water injection pump (not shown) is connected to the cooling water inlet 5, which applies pressure to cooling water stored in a cooling water reservoir to inject cooling water A into the cooling water passage inside the handpiece housing 3 through the inlet 5. Cooling water A injected into the cooling water passage through the cooling water inlet 5 under the pressure applied by the injection pump moves toward the open outlet of the handpiece housing 3 while covering the vibrating horn 2. Although the use of a cooling water injection pump is illustrated in this embodiment, the cooling water A does not necessarily need to flow above a certain pressure or a certain speed, so the use of a cooling water injection pump may be omitted. Cooling water A functions to cool the vibrating horn 2, the temperature of which has increased due to ultrasonic vibration. Another important function of cooling water A is to transmit ultrasonic waves to cleaning solution B (shown in yellow in FIG. 10). As shown by the arrow near the outlet of handpiece housing 3 in FIG. 10, cooling water A, which cools vibrating horn 2 and transmits ultrasonic waves to cleaning solution B, may overflow and be discharged into the gap between the cleaning device and the teeth. In another embodiment, a separate suction means may be added to prevent cooling water A from overflowing and being discharged into the gap between the cleaning device and the teeth, and cooling water A may be sucked in and collected.

[0070] An irrigation solution nozzle 7 for injecting irrigation solution B into the inside of the tooth is disposed at the outlet of the handpiece housing 3. The irrigation solution nozzle 7 is connected to the irrigation solution passage 6, which is connected to a irrigation solution injection pump (not shown) that provides pressure. In this embodiment, the use of a irrigation solution injection pump is illustrated, but any means other than a pump that can apply injection pressure to the irrigation solution B discharged through the irrigation solution passage 6 and the nozzle 7 can be used in the irrigation device according to the present invention.

[0071] The function of the irrigation solution nozzle 7 is explained below. Figure 11 illustrates the function of steam bubbles and nozzle 7 during root canal irrigation. As shown in Figure 11, contaminants adhering to the root canal wall are detached from the wall by the cleansing power of steam bubbles. Even after detaching from the wall, contaminants may continue to remain within the root canal. However, nozzle 7 is essential for expelling them from the root canal. Figure 11 conceptually illustrates "contaminant removal by jet flow" using a red broken arrow. The irrigation solution sprayed into the root canal cavity of a tooth by nozzle 7 and introduced into the root canal generates a jet flow within the root canal, expelling contaminants detached from the wall by the cleansing power of steam bubbles to the outside of the root canal. The jet flow generated by nozzle 7 also solves the problem of gas bubbles clogging the root canal and hindering irrigation.

[0072] Figure 12 is a photograph showing gas bubbles blocking a model root canal and hindering irrigation. One of the features of the present invention is the use of degassed liquid as cooling water A and irrigation solution B. While this feature minimizes the generation of gas bubbles in the root canal during irrigation, it does not guarantee that the degassed liquid is 100% degassed. Therefore, gas bubbles are intermittently generated due to the strong ultrasonic sound pressure that generates steam bubbles in the degassed liquid. As explained in the section on gas bubbles and steam bubbles in this specification, gas bubbles have a longer lifespan than steam bubbles. Therefore, if gas bubbles block the root canal, the blocked area cannot be irrigated for a long time, and gas bubbles blocked in the root canal must be removed by applying external force. The inventors have confirmed that the jet flow generated by nozzle 7 applies external force to gas bubbles blocked in the root canal, easily expelling them from the root canal. Conversely, it was also confirmed that gas bubbles were not discharged in a structure that did not use the nozzle 7. Next, the stability of the irrigation liquid nozzle 7 in discharging the irrigation liquid to the root end will be described.

[0073] FIG. 13 shows an experiment evaluating the stability of root-end outflow of the nozzle 7 used in an irrigation device according to an embodiment of the present invention. The inventors compared the stability of the spray nozzle employed in an irrigation device according to an embodiment of the present invention with that of needle irrigation (a conventional method used for tooth irrigation) by measuring root-end pressure. The higher the pressure at the root end, the greater the risk of outflow in actual clinical practice. The method currently used for root canal irrigation in dentistry and the method according to an embodiment of the present invention are both shown on the left side of FIG. 13. The diameter of the needle that functions as the spray nozzle is the same, 30 gauge (150 μm). However, the needle employed in the irrigation device according to the present invention is a standard needle, while the needle employed in the conventional syringe irrigation device (control group) is a side-vented needle. The conventional technology adopted a side-vented needle to address the problem of excessive pressure applied to the root end when using a standard needle. When comparing the two, the biggest difference is in the needle's injection position. In the prior art, the irrigation fluid is sprayed at the entrance of the root canal to inject it into the inside of the root canal. On the other hand, in one embodiment of the present invention, the irrigation fluid is sprayed at the root canal cavity, which is located somewhat away from the root canal. When the irrigation fluid jet flow rate of the irrigation device according to one embodiment of the present invention was set to either 15 m / s or 20 m / s, the root end pressure was measured to be much lower than in the prior art. Therefore, it can be said that the use of the irrigation device according to one embodiment of the present invention resulted in significantly improved stability in root end outflow compared to the prior art.

[0074] Next, with reference to FIGS. 10 and 14, the bubble trapping space installed in the handpiece housing 3, which is one of the unique features of the present invention, will be described. The bubble trapping space 8 is indicated by reference numeral 8 in FIG. 10. The bubble trapping space 8 is designed to confine enlarged bubbles C in one location. When bubbles C, which are unnecessarily generated gas bubbles, gather near the acoustic reflector 4, the ultrasound transmission efficiency drops sharply. The inventors provided the bubble trapping space 8 in the handpiece housing 3 so that enlarged bubbles C can rise due to buoyancy and be trapped in a specific space. The bubble trapping space 8 may be dome-shaped as shown in FIGS. 10 and 14, but may have any shape as long as it can trap the bubbles C. Because the bubble trapping space 8 is used to trap bubbles C that gather near the acoustic reflector 4, it is preferable that this space be formed near the acoustic reflector 4 in the handpiece housing 3. As shown in Figures 10 and 14, providing a bubble collection space 8 at the edge of the top surface of the handpiece housing 3 connected to the acoustic reflector 4 tilted at a 45-degree angle is effective in capturing bubbles C that gather around the acoustic reflector 4 and reduce ultrasound transmission efficiency. Of the three states shown in Figure 14, the left state shows the correct use of the cleaning device according to one embodiment of the present invention, i.e., the state in which the handpiece of the cleaning device is used horizontally. Thus, the bubble collection space 8 is necessary when the handpiece of the cleaning device is placed horizontally. When the handpiece is tilted, as in the center and right states of Figure 14, bubbles do not gather around the acoustic reflector 4. When the cleaning device according to the present invention is used with the handpiece horizontal, capturing bubbles C in the bubble collection space 8 and maintaining good ultrasound transmission efficiency should be understood as one of the important features of the present invention.

[0075] The inventors have verified the cleaning effect using the cleaning device with the above-described structure under the cleaning conditions summarized in the following table.

[0076] [Table 1]

[0077] The inventors applied the root-end closed condition, as shown in the table above, to artificially create an environment that is difficult to clean. The open root-end condition is a relatively easy condition for cleaning. If effective cleaning is possible even under the closed root-end condition, the cleaning effect under the open root-end condition is fully guaranteed. The results of an experiment verifying this cleaning effect are shown in Figure 15. The inventors conducted an experiment using a transparent root canal model, as shown in the photograph in Figure 15, and observed the root canal cleaning process. The following three important results were confirmed. First, when cleaning a root canal model using a cleaning device according to an embodiment of the present invention, simultaneous cleaning of multiple root canals was confirmed to be equivalent to that of the uncontaminated root canal. Second, even when both cleaning solution B and cooling water A were used as degassed liquids, steam bubbles were generated within the root canal, and cleaning was confirmed through these actions. Thirdly, it was confirmed that gas bubbles are formed intermittently and block the narrow and thin root canal, but the gas bubbles are expelled to the outside of the root canal by the jet flow of nozzle 7.

[0078] Finally, the ultrasonic sound pressure and the spray pressure of the cleaning liquid in the cleaning device according to the embodiment of the present invention will be described.

[0079] The inventors conducted repeated experiments to generate vapor bubbles in a cleaning liquid, i.e., a degassed liquid, and found that the critical value of ultrasonic sound pressure is approximately 80 kPa. To generate ultrasonic sound pressure exceeding the critical value and smoothly generate vapor bubbles in the degassed liquid, the inventors actually generated ultrasonic sound pressures of 150 kPa to 220 kPa using the sound pressure generator of a cleaning device prototype. The inventors sprayed cleaning solution B from nozzle 7 attached to the cleaning device prototype at a spray pressure of approximately 6 bar to 12 bar. When this spray pressure was applied, the spray velocity of cleaning solution B from nozzle 7 was recorded as approximately 15 m / s to 20 m / s. The ultrasonic sound pressure, spray pressure, and spray velocity described above are merely examples and do not limit the structure of the cleaning device according to the present invention. The above values ​​should be used for reference purposes to demonstrate that ultrasonic sound pressure, spray pressure, and spray velocity can be achieved within these approximate ranges when using the cleaning device according to the present invention, thereby enabling smooth cleaning.

[0080] The liquid jet used in the U.S. patent registered by Sonnendo, Inc., described in the background art section of this specification, has a minimum spray pressure of 7,000 psi (approximately 483 bar) and a minimum spray velocity of 50 m / s. When these figures are compared with the spray pressure and spray velocity realized for root canal irrigation in the irrigation device according to the present invention, it becomes clear that the cleaning effect can be maximized while spraying the irrigation liquid at a lower speed and pressure than in the prior art, which uses a high-speed, high-pressure liquid jet for root canal irrigation. Therefore, the main effect of the present invention can be clearly understood, that is, it is possible to provide a root canal irrigation device that is far more advanced in terms of stability while reducing the production cost of the equipment.

[0081] Although the present invention has been described above using specific details such as specific components and limited examples and drawings, this is merely provided to facilitate a more general understanding of the present invention, and the present invention is not limited to the above examples. Those skilled in the art will be able to make various modifications and variations from such descriptions.

[0082] Therefore, the concept of the present invention should not be limited to the embodiments described above, and it can be said that not only the scope of the claims described below, but also all modifications equivalent to or similar to the scope of these claims fall within the scope of the concept of the present invention.

Claims

1. a sound pressure generating device that operates by applying power; a handpiece housing that accommodates the sound pressure generating device; a cooling water passage formed inside the handpiece housing; a cooling water inlet formed in the handpiece housing and communicating with the cooling water passage; an irrigation fluid nozzle mounted on the handpiece housing; The ultrasonic sound pressure applied to the cooling water by the sound pressure generator is transmitted to the cleaning solution, and the transmitted ultrasonic sound pressure generates steam bubbles in the cleaning solution, and the steam bubbles act on the tooth to be treated together with the cleaning solution, thereby removing the objects to be cleaned inside the tooth, including the root canal. A root canal irrigation device, wherein the irrigation liquid is a degassed liquid.

2. The cooling water cools the sound pressure generating device, 2. The root canal irrigation device according to claim 1, wherein the cooling water is a degassed liquid.

3. 3. The root canal irrigation device according to claim 2, wherein the sound pressure generating device includes: a vibrator that vibrates when power is applied; and a vibration horn that is connected to the vibrator, vibrates, and has a linear extension.

4. The root canal irrigation device according to claim 3, wherein the jet flow formed in the root canal by the irrigation liquid nozzle expels gas bubbles blocking the root canal passage and / or contaminants detached from the root canal to the outside of the root canal.

5. 5. The root canal irrigation device according to claim 4, wherein the handpiece housing has a bent end, an acoustic reflector is installed at the bent portion, and ultrasonic waves applied to the cooling water by the vibration horn are reflected by the acoustic reflector.

6. 6. The root canal irrigation device according to claim 5, wherein the acoustic reflector is disposed at a predetermined angle with respect to a cross section of the vibration horn.

7. A bubble collecting space is formed on the upper surface of the handpiece housing, 7. The root canal irrigation device according to claim 6, wherein air bubbles that gather near the acoustic reflector rise to the air bubble collecting space due to buoyancy and are collected in the air bubble collecting space.

8. The root canal irrigation device according to claim 7 , wherein the length of the irrigation liquid nozzle is set so as to spray irrigation liquid into the root canal cavity of the tooth during root canal irrigation.

Images