Dental pulp apparatus and methods

Abstract

Disclosed are dental apparatuses (1) and methods, such as endodontic apparatuses and methods. The apparatuses include a supply (12) of fluid, a pump (14) for delivering the fluid from the supply (12) under pressure, and a handpiece (20) in fluid communication with the pump (14). The handpiece (20) includes a needle (30) extending from a rearward end proximate the handpiece to a forward tip distal from the handpiece, a lumen of the needle extending to an opening at the tip to deliver fluid received from the pump to a tooth. The needle is sized and the delivery pressure of the fluid is selected such that a flow of the fluid through the needle causes an inertial cavitation cloud to form forward of the needle tip.

Description

Technical Field

[0001] This invention relates to dental devices and methods, particularly dental pulp devices and methods for pulp debridement, irrigation and / or disinfection. Background Technology

[0002] Root canal treatment is used to protect teeth in cases of severe infection. A typical root canal procedure involves the following steps: (i) opening the cavity and accessing the pulp and root canal; (ii) enlarging the canal using mechanical instruments and files; (iii) chemical rinsing with sodium hypochlorite (bleach, NaOCl), EDTA, and / or other chemical reagents (using a syringe), usually repeated multiple times; (iv) optionally activating the NaOCl / chemical reagents with an ultrasonic cleaner; and (iv) filling (or filling) the root canal and sealing the tooth. This multi-step procedure is very strenuous and can take approximately 60 minutes to complete.

[0003] While these procedures are commonly performed (approximately 55 million worldwide annually), they are laborious and time-consuming, with a relatively high failure rate (roughly 30% of cases). This leads to expensive and complex retreatments, extractions, or costly implants. The primary causes of this failure are incomplete bacterial removal or weakened tooth structure due to mechanical filing. Incomplete bacterial removal is a consequence of the limitations of the combination of mechanical filing and syringe flushing, which fails to access all the very small (e.g., less than 300 μm or 100 μm) and complex tubular structures of the tooth, leaving bacteria behind and subsequently causing reinfection. Weakened tooth structure results from the enlargement of the tubules to provide better access for NaOCl. This weakens the dentin structure and makes the roots more susceptible to fracture.

[0004] Some common problems dentists face when performing root canal procedures include one or more of the following: the time and effort required to enlarge the canal; the risk of weakening the tooth structure by filing the canal; the risk of failure to remove bacteria from the smallest canal, either because the smallest canal is not found and / or because the irrigator does not reach it, in order to prevent reinfection through the small canal; vapor lock occurring and / or being detected in the canal (when air is trapped and cannot escape and pass over the liquid above, preventing the irrigator from disinfecting the top third of the canal); the risk of NaOCl being squeezed through the tip into the soft and hard tissues; and / or blood flowing in from outside the tooth.

[0005] Several systems are commercially available that offer improved root canal irrigation and address or alleviate at least some of the problems mentioned above. Such systems are designed to provide enhanced hydrodynamic action within the irrigation fluid to deliver improved cleaning and / or disinfection.

[0006] One such system is the one that uses negative pressure aspiration to prevent the development of vapor lock; an example is the EndoVac system (available from Discus Dental in Culver City, California). This system uses continuous tip-level negative pressure flushing, in which fresh flushing fluid is slowly injected into the pulp chamber at the tip using a large needle. This fresh flushing fluid is then aspirated into a cannula at the bottom of the tube. A problem with this system is that it requires a large number of instruments to adequately expand the cannula to accommodate two flushing needles.

[0007] Other types of systems are acoustic or ultrasonic systems, which use vibrating plastic or metal tips inserted into the root canal. Typically, the vibration frequency is between 100 Hz and 20 kHz. Vibration can prevent airlock formation and can improve debridement and / or disinfection, especially in larger canals. Examples of such systems include the EDDY system (available from VDW in Munich, Germany), the Endoactivator system (available from Dentsply Sirona in York, Pennsylvania, USA), and the Irrisafe system (available from Acteon in Norwich, UK). However, without a large number of prior instruments and the ability to file the canal, such systems generally operate only within very limited scope.

[0008] Other types of systems are closed hydrodynamic activation systems, including the Gentlewave system (available from Sonendo, Inc., Laguna Hills, California) and the system disclosed in U.S. Patent 4,993,947. In closed systems, components such as the crown head are positioned within the pulp chamber and tightly attached to form a closed system with the tooth. The requirement for a fluid-tight connection between the tooth and the system necessitates additional work as part of the dental procedure. A pump supplies alternating flows into and out of the root canal, which gradually removes debris. To enhance the hydrodynamic action of the irrigator within the tooth canal, US 4,993,947 passes the fluid through a Venturi nozzle before delivery into the tooth, creating cavitation that flushes the entire volume of the root canal (including narrow tubes) and increases penetration into the root tissue. In the Gentlewave system (available from Sonendo, Inc., Laguna Hills, California), the enhancement of the hydrodynamic action arises from the interaction of the incoming water jet with a platform formed as part of the crown head. However, in addition to the major drawback of establishing a troublesome and tight fixation on the teeth, the alternating flow system has shown significant problems with negative pressure (or insufficient pressure) at the tip, which subsequently leads to blood flow into the tip area and inefficient disinfection and debridement.

[0009] Open-system hydrodynamic activation has also been proposed, such as the RinsEndo system (available from Durr-Dental in Bittigheim-Biesingen, Germany) and the systems shown in U.S. Patents US4,247,288 and US6,224,378. For example, the RinsEndo system uses a special disposable cannula designed to allow irrigants to be delivered deeper into the root canal. US6,224,378 uses high-pressure, high-velocity water or other liquid hydrodynamic jets designed to remove soft tissue within the tooth, but has limited ability to cut or erode hard, calcified tooth tissue.

[0010] Finally, laser activation systems, such as photon-induced photoacoustic flow (PIPS) or SWEEPS (shock wave enhanced emitted photoacoustic flow) (available from Fotona in Ljubljana, Slovenia), can be used to enhance flushing by inserting fiber optic systems inside the medullary tract. In such systems, the laser is used to superheat the water to generate cavitation.

[0011] While many root canal activation systems claim to generate “cavitation” to ensure effective root canal disinfection, the applicant found this insufficient in practice. For example, in many systems, the generated cavitation is limited and manifests as non-inertial cavitation, where air bubbles in the fluid oscillate only in size and / or shape. Non-inertial cavitation does not cause bubble collapse, which results in powerful shock waves, as seen in inertial cavitation. Furthermore, the applicant found that many existing solutions fail to generate the cavitation required for effective cleaning, debridement, and / or disinfection within the narrow tubular portions of teeth (sizes less than 1 mm, less than 500 μm, or even less than 300 μm or 100 μm). Finally, existing devices cannot be used to eliminate or reduce the need for mechanical filing, a leading cause of root fracture. These existing devices are used only as irrigator activation devices to enhance the disinfection capabilities of the irrigator.

[0012] Therefore, there remains a need for improved equipment and methods to provide rapid and reliable cleaning of necrotic tissue, debris, and bacterial biofilm in root canals. In particular, there is a need for equipment and methods that eliminate or reduce the need for mechanical filing and can, for example, significantly reduce the required treatment time. Embodiments of the present invention address these needs and overcome at least some of the known problems of root canal surgery. Summary of the Invention

[0013] According to a first aspect of the invention, a dental pulp device (e.g., a device for pulp debridement, irrigation, and disinfection) is provided, the device comprising: a supply of irrigant fluid; a pump for delivering irrigant fluid from the supply under pressure; a handpiece in fluid communication with the pump and the handpiece including a needle extending from a rearward end near the handpiece to a forward end away from the handpiece, the lumen of the needle extending to an opening at the end to deliver irrigant fluid received from the pump into a tooth cavity; and wherein the length of the needle extending from the rearward end to the end of the needle is at least 3 mm, and the outer diameter of the needle at the end does not exceed 520 μm, such that the needle tip can be positioned within a portion of a root canal; and the diameter of the lumen at the end is at least 50 μm, and the pump delivers irrigant at a delivery pressure exceeding a threshold cavitation pressure, such that the flow of irrigant through the needle causes an inertial cavitation cloud to form in front of the needle tip, within the irrigant fluid in the root canal.

[0014] The applicant has recognized that inertial cavitation within the root canal is important for providing effective debridement and / or disinfection. For this cavitation to occur, the needle tip must be of sufficient length and must have a sufficiently large inner diameter. Needles with an outer diameter of less than 520 μm are small enough to penetrate at least the coronal portion of the root canal, in contrast to many existing devices where the needle is only inserted into the pulp chamber.

[0015] Unbound by any particular theory, the applicant argues that in order to generate a cavitation cloud that will effectively clean the root canal and to avoid excessive outflow at the tip, it is desirable to generate backflow within the root canal. This backflow requires the needle to provide sufficient clearance within the root canal to allow the outflowing flow to pass between the side of the needle and the side of the root canal. Backflow provides a significant shear layer within the irrigant in the root canal. This shear layer causes strong vortices to form at the interface between the inward and outward flows within the root canal. Within these vortices, the (dynamic) pressure is greatly reduced, and this pressure reduction will make cavitation more favorable. Furthermore, cavitation not only cleans, irrigates, and disinfects the canal, but the flow also serves as a highly efficient mechanism for removing any debris or bacteria.

[0016] Once the needle is positioned within the root canal (in a manner that allows for the establishment of backflow), the specific pressure required to generate an inertial cavitation cloud can be selected based on the particular needle and canal geometry. For example, such a threshold pressure can be determined for various needle sizes.

[0017] The applicant also found that providing a lumen with a diameter of at least 50 μm at the tip helps ensure sufficient flow at the needle tip, unaffected by frictional pressure losses as the flushing fluid passes through the lumen of the needle. Selecting a delivery pressure above a threshold cavitation pressure (e.g., based on the specific geometry of the needle and root) ensures that the flow of flushing fluid leaving the needle has a velocity that causes an inertial cavitation cloud to form in front of the nozzle tip, within the flushing fluid fluid.

[0018] The pump can be a mechanical pump or a compressed gas pressurization system. The pump can provide delivery pressures between 5 bar and 300 bar. For example, the delivery pressure can be between 5 bar and 100 bar. The applicant has found that, depending on the selected needle size and needle length, the threshold cavitation pressure in the embodiments can be between 5 bar and 80 bar.

[0019] The needle length can be at least 5 mm. The length can be, for example, between 10 mm and 30 mm (e.g., the needle length can be between 10 mm and 20 mm). Choosing an appropriate needle length balances the following requirements: ensuring that the tip can be properly positioned within the root canal, and ensuring that frictional flow loss in the needle is acceptable.

[0020] The delivery pressure can be selected such that the minimum exit velocity of the irrigating fluid at the needle tip is at least 20 m / s (and, for example, at least 40 m / s, 60 m / s, 80 m / s, 100 m / s, 150 m / s, 200 m / s, or 300 m / s). The flow rate of the irrigating fluid through the needle is less than 175 ml / min (and, for example, less than 75 ml / min, 50 ml / min, 25 ml / min, 10 ml / min, or 5 ml / min). In contrast, prior art systems may use NaOCl flow to irrigate the tube at flow rates up to 1 ml / s, which presents a much greater risk of inducing pain or injury than the embodiments of the present invention.

[0021] According to the Birmingham specification system, needles can have a needle specification between 25G and 34G (e.g., between 30G and 34G). The needle specification can be specified and measured at the tip of the needle, such that the distal end of the needle has a needle specification between 30G and 34G.

[0022] It should be understood that the size of the needle (i.e., the outer diameter and / or lumen diameter) is usually defined based on the properties at the tip of the needle (because the size may not be constant along the length of the needle).

[0023] Because embodiments of the invention utilize the hydrodynamic effects of cavitation clouds to provide debridement and / or disinfection, it is unnecessary to use chemical disinfectants such as NaOCl for rinsing. Therefore, advantageously, embodiments of the invention use water or saline solution as the rinsing fluid. Compared to chemical disinfectants such as NaOCl, saline solutions, especially physiological saline solutions (e.g., 0.9% NaCl), are generally better tolerated by the body when squeezed beyond the tip and are less likely to cause significant pain or discomfort to the patient.

[0024] In an embodiment, the size of the cavitation cloud extends 1 mm, 3 mm, 5 mm, 7 mm, 10 mm, 15 mm, or 20 mm beyond the distal end of the needle, and the position and size of the cavitation cloud are adjusted by changing the needle size, exit velocity, and / or flow rate.

[0025] In an embodiment, the needle should be flexible and laterally bendable in order to pass through complex tubes.

[0026] Rinse fluids, such as brine, may include one or more additives. For example, rinsing fluids may also include disinfectants. Disinfectants can enhance the bactericidal effect of the rinsing fluid. Rinse fluids can be low surface tension liquids, making cavitation easier to occur at lower pressures and / or temperatures; for example, ethanol can be used as a low surface tension liquid, and ethanol is also a disinfectant. The viscosity of the liquid is also a variable in the cavitation conditions of the rinsing fluid, therefore low-viscosity fluids can be selected as rinsing fluids. Low surface tension fluids and / or low-viscosity fluids can be rinsing fluids selected to have these properties, or additives that reduce these properties of the rinsing fluid.

[0027] The flushing agent can also be selected or customized to increase its abrasive impact. For example, the density of the flushing agent can be increased and / or the flushing fluid can also include abrasive particles (e.g., solid particles suspended in the fluid).

[0028] The device according to the embodiment can use a needle with a forward-facing axial opening. Such a needle with a forward-opening end generally produces better forward flow of the rinsing agent, whereas many prior art configurations avoid using such a needle compared to the embodiments of the present invention because of the risk of pushing corrosive rinsing agents such as NaOCl beyond the tip of the tooth and causing significant pain and serious complications.

[0029] The device may include a regulator for controlling the delivery pressure. This allows the operator to adjust the delivery pressure, for example, taking into account the different geometries of teeth or root canals.

[0030] In embodiments, the device may further include a heater to control the temperature of the flushing agent. The heater may be configured as part of the supply section (such that the heater can substantially heat the flushing agent before it is pumped or heat the flushing agent). Alternatively, the heater may be configured as part of the handpiece, such that the heater heats the flushing agent as it flows through the handpiece. The phase boundary of the flushing agent depends on both temperature and pressure, and for any given temperature, increasing the temperature of the flushing agent will provide more favorable conditions for cavitation. For example, the temperature may be increased to greater than 20°C. The temperature of the flushing agent may also be selected to avoid any painful reaction, and therefore the temperature may be less than 60°C (or less than 50°C).

[0031] In some embodiments, the device may further include a pulse generator to pulse the flow of the flushing fluid. The pulse generator may be, for example, a single-piston pump, a controllable pressure relief valve between the pump and the needle, or an on / off valve between the pump and the needle.

[0032] According to another aspect of the invention, a pulp irrigation method is provided, the method comprising: positioning a needle within a portion of a root canal, the needle having a length of at least 5 mm and a distal outer diameter not exceeding 520 μm; supplying an irrigating fluid to the needle under pressure such that the fluid is discharged from the needle tip into the root canal; and the delivery pressure of the irrigating fluid being selected such that the pressure at the needle tip exceeds a threshold cavitation pressure, thereby causing an inertial cavitation cloud to form in front of the needle tip and within the irrigating fluid in the root canal by the flow of irrigating fluid through the needle.

[0033] The delivery pressure can be selected from the range of 5 bar to 300 bar. In particular, the delivery pressure can be selected from the range of 5 bar to 100 bar.

[0034] The method may also include heating the flushing fluid. For example, the flushing fluid may be heated to between 20°C and 57°C.

[0035] The method may also include adjusting the pressure based on the depth to which the needle is inserted into the tube.

[0036] Some embodiments may include a pulsed supply of the irrigating fluid. The pulsed flow (rather than a continuous flow) allows the bursting flow to back up upon impact, resulting in an increase in the force (rate of change of momentum) within the irrigating fluid. This increases the erosive potential of the flow and thus further increases debridement and / or disinfection efficiency. Pulsed flow also offers the advantage of reducing the total amount of irrigating fluid used.

[0037] According to another aspect of the invention, a dental device is provided, comprising: a fluid supply section; a pump for delivering fluid from the supply section under pressure; a handpiece in fluid communication with the pump and the handpiece including a needle extending from a rearward end near the handpiece to a forward end away from the handpiece, the lumen of the needle extending to an opening at the end for delivering fluid received from the pump to the teeth; and wherein the size of the needle and the fluid delivery pressure are selected such that the flow of fluid through the needle causes an inertial cavitation cloud to form in front of the needle tip.

[0038] For example, the needle size can be selected based on the required surgical procedure. For instance, the procedure may include one or more of the following: cleaning and / or disinfecting cavities, removing plaque from the outside of the tooth or at the subgingival surface, drilling through tooth tissue (dentin, enamel), cutting soft tissue, or locating the entrance to a root canal. The needle length can be selected to ensure proper placement of the needle tip during use. The needle size can be selected to ensure sufficient flow through the needle while also ensuring proper positioning of the needle tip. The size can also be selected to ensure fluid backflow is close to the flow formation of the fluid ejected from the needle.

[0039] Unless otherwise stated, each integer described may be used in combination with any other integer that a person skilled in the art would understand. Furthermore, while all aspects of the invention preferably “comprise” the features described with respect to that aspect, it is specifically contemplated that such aspects of the invention may “consist” or “essentially constitute” by those features outlined in the claims. Moreover, unless specifically defined herein, all terms are intended to be given the meaning commonly understood in the art.

[0040] Furthermore, in the discussion of this invention, unless otherwise stated, the disclosure of alternative values ​​for the upper or lower limit of the permissible range of a parameter should be interpreted as implying that each intermediate value of the parameter located between a smaller and a larger alternative value is itself disclosed as a possible value of the parameter.

[0041] In addition, unless otherwise stated, all numerical values ​​appearing in this application should be understood to be modified by the term “about”.

[0042] Although the invention has been described above, it extends to any inventive combination of features set forth in the description or drawings above or below. Attached Figure Description

[0043] Embodiments of the invention can be implemented in various ways, and will now be described by way of example only with reference to the accompanying drawings, in which:

[0044] Figure 1 A schematic diagram of a device according to an embodiment of the present invention is shown;

[0045] Figure 2 It shows Figure 1 The diagram shows details of the needle's position inside the tooth; and

[0046] Figures 3(A), 3(B), 3(C), and 3(D) illustrate the working principle behind the embodiments of the present invention. Detailed Implementation

[0047] It should be noted that the terms proximal and distal are used herein for convenience in referring to the device in its usual orientation of use. Therefore, it should be understood that proximal generally refers to a surface, component, or orientation that is close to the operator's hand during use, while distal generally refers to a surface, component, or orientation that is far from the operator's hand (and thus close to the root canal). Similarly, forward will be understood as being used relative to the direction away from the proximal end and toward the distal end (while backward will be understood as the opposite direction). However, it should be understood that this reference is not intended to be restrictive, and the device may be used in any orientation.

[0048] Figure 1 The image schematically illustrates a pulp irrigation device 1. The device includes a base unit 10, which includes a reservoir 12 and a pump 14. The reservoir 12 contains a supply section for irrigation fluid, and the pump 14 delivers the irrigation fluid under pressure from the supply section through a flexible conduit 16. The base unit 10 may also include a user interface 18 (which may be of any convenient form) and allow the operator to adjust operating parameters, such as the pressure output of the pump 14.

[0049] Handheld component 20, for example via a conventional removable connector, is connected to the distal end of the flexible conduit 16, such that handheld component 20 is in fluid communication with the base unit 10 and can receive flushing fluid from the supply unit 12 via pump 14. Handheld component 20 includes a grip portion 22 at a proximal end and a head 24 connected to the grip portion 22 via a neck 23. Head 24 extends to a needle 30, which can typically be replaceably mounted into head 24. It is understood that, as used herein, the term "needle" broadly refers to a thin, elongated conduit having an orifice (the "lumen" of the needle) extending through the elongated conduit and from a proximal end to an opening at a distal end for receiving a supply of fluid in use and for delivering fluid in use. Figure 2 As best viewed, the needle extends axially from the proximal end 33 to the distal end 34 and has a length of l. A lumen 32 extends through the length of the needle 30 to provide a passage for flushing. The end 34 of the needle terminates with a forward-facing axial opening, allowing flushing fluid to exit from the lumen in a forward axial flow.

[0050] In use, the needle 30 is inserted into the tooth 100 via a cavity 110 (formed by any convenient means, such as by drilling), the cavity 110 providing an entrance to the pulp chamber 120. According to an embodiment of the invention, the needle has a length of at least 5 mm measured in direction l and an outer diameter of no more than 520 μm measured in direction d, such that the needle tip 34 can be positioned within a portion of the root canal 130. By positioning the needle in this manner, the applicant has surprisingly discovered that, under conditions where irrigant is supplied in a manner that establishes an inertial cavitation cloud in front of the needle tip 34, the needle will provide effective debridement and / or disinfection without the need for NaOCl-based irrigants. In contrast, many prior art systems use needles that are either too short to reach the root canal themselves (instead, merely positioning the tip in the cavity 100 or pulp chamber 120), and / or have a diameter too large to enter the root canal.

[0051] Furthermore, embodiments of the invention enable root canal treatment (at least in all cases except the most difficult—e.g., elderly patients with calcified and narrowed canals) without the need for mechanical filing, requiring only the initial inlet to the root canal to be formed before using the device of the invention. To provide this inertial cavitation cloud, the applicant has found that the needle's inner diameter (i.e., the diameter of the lumen) and the delivery pressure exceeding the threshold cavitation pressure should be selected (based on the geometry of the specific tooth and needle combination) such that the flow of irrigant through the needle causes an inertial cavitation cloud to form in front of the needle tip, within the irrigant fluid in the root canal. For example, the lumen diameter can be at least 25 μm, such as at least 50 μm. Without understanding this effect, it may be natural to select a needle with an excessively small inner diameter (e.g., less than 50 μm to ensure the needle fits the root canal), but the applicant recognizes that, importantly, such a needle will generate frictional losses, meaning that even very high delivery pressures will not provide a flow exiting the needle with effectively established cavitation. In contrast, in embodiments of the present invention, cavitation provides powerful debridement, disinfection, and / or removal of debris or bacteria due to the well-known erosive effect caused by shock waves, which are generated by the rapid collapse of vapor bubbles within the fluid.

[0052] As shown in the 16,000fps high-speed photograph in Figure 3(A), a glass micropipette (e.g., with an inner diameter of 1.2 mm or 0.6 mm) can be used to simulate a root canal. With a suitably sized needle 330 inserted into the canal 350 and flow provided at a pressure exceeding the cavitation threshold, a cavitation cloud 360 is clearly formed downstream of the needle. The flow within the canal 350 is schematically illustrated in Figure 3(B). Importantly, the needle size (not exceeding 520 μm) ensures that the fluid flow in the canal (or a real root canal) includes inflow from the needle and outflow passing between the canal wall and the outside of the needle.

[0053] Cavitation occurs under suitable conditions when a liquid rapidly transforms into a gas across a phase boundary. Without being bound by any particular theory, the applicant has recognized, as illustrated in Figure 3(C), that selecting a needle that enables backflow in the root canal creates a strong shear layer effect between the inward and outward flows. This shear layer increases vortices in the flow and significantly increases the occurrence of cavitation. The resulting situation means that very strong vortices can be generated at the interface between the inflow and outflow within the root canal. Inside the vortices, the (dynamic) pressure is greatly reduced. This pressure reduction makes cavitation more favorable (bringing the initiation point closer to the phase boundary). The result of this effect is the formation of cavitation clouds within channels such as root canals, even under flow conditions (pressure, velocity, and flow rate) that would not establish cavitation in an open environment. Increasing the velocity of the liquid present in the needle also helps to increase vortices, and for a given passage, there will be a minimum nozzle exit velocity below which cavitation will not occur. Provided the needle's inner diameter is not too narrow, the needle exit velocity can be controlled using the delivery pressure.

[0054] To test the performance of the device according to the embodiment, a clear plastic tooth (RepliDens mandibular molar, clear type 03.2.1, Medichem, V.M., Switzerland) with a realistic root canal structure filled with colored gelatin to simulate the tissue inside the tooth was tested. Different devices were tested, and the amount of gelatin before and after cleaning was measured using image analysis and pixel counting. The device according to the embodiment used a needle with a length of 20 mm and a 30G specification (corresponding to an inner diameter of 0.16 mm and an outer diameter of 0.31 mm). The delivery pressure was set to 60 bar. The irrigant was a saline solution, and the needle was positioned and moved up and down in the canal for 180 seconds. The results of multiple root canal systems were compared based on the amount of gelatin before and after cleaning to determine the percentage of material removed. The same tests were performed using commercial ultrasonic-based irrigator activation systems and laser-based irrigator activation systems. In the case of ultrasound (EDDY, VDW, Munich, Germany), a vibrating end was inserted into each canal and activated for 120 seconds. For the laser system (LiteTouch Er: YAG Laser, Orcos Medical, Küsnacht, Switzerland), a plastic pulp chamber was filled with water, the laser tip was placed into the plastic pulp chamber, and activation was performed for 120 seconds. The results are shown in Table 1 below, where the embodiments of the present invention provided significantly improved debridement in instrumentless teeth (our invention) compared to commercially available systems (ultrasonic system (no instruments / no filing), laser system (no instruments / no filing), and mechanical filing with instruments followed by syringe irrigation (ProTaper, Dentsply, Baleg, Switzerland)). Experiments revealed that conventional ultrasonic and laser activation systems were unable to adequately remove material from the inside of the canal. Therefore, conventional ultrasonic and laser activation systems are only suitable for activation and not for treating instrumentless canals, and do not reduce the need for mechanical filing. In the case of the ultrasonic system, the tip could not vibrate laterally due to the narrow root canal, thus suppressing oscillation. In the case of the laser system, we observed no gelatin flowing out of the root canal because insufficient flow was generated. Mechanical filing, combined with rinsing using a water-filled syringe, performs better, but is less efficient and significantly more time-consuming than the embodiments of the present invention.

[0055] Table 1: Cleaning effects of different systems in dental models without instruments

[0056]

[0057]

[0058] Importantly, the applicant also compared the results between open-ended and closed / restricted areas (where the tooth root is sealed). This demonstrated unexpected results and illustrates the importance of the geometry of the tooth tube and needle for cavitation. It is believed that existing systems fail to account for the geometry of the tooth tube and needle, and this reflects why such systems may not provide truly effective cavitation.

[0059] To demonstrate this effect, we conducted experiments using a delivery pressure of 60 bar connected to needles of different shapes, diameters, and lengths. Water exiting the needles was sprayed into (i) a basin containing water, (ii) a glass micropipette with an open end, or (iii) a glass micropipette completely sealed at one end. Needles tested included those of standard specification size. The threshold pressure was recorded as the point at which a stable cavitation cloud first became visible. The threshold for well-developed cavitation is generally much lower inside a closed, narrow tube compared to an unconstrained basin of water. The experimental data show that 30G (needle specification) needles with 20 mm or 15 mm diameters produced cavitation only inside the micropipette, not in an open basin, where higher pressures were required to produce cavitation. All other needle sizes, including 30G needles with 10 mm or 5 mm lengths, produced cavitation in open water. However, using these other needle sizes inside a micropipette reduced the required upstream pressure by 15 to 40 bar. An exception exists with 25G needles and 0.6mm tubing (Table 2; end-sealed micropipettes d = 0.6mm, 25G). In this case, the needle itself blocks backflow, and therefore the cavitation threshold increases after the micropipette end is sealed (because the outer diameter of the needle is very close to the inner diameter of the pipette). Thus, the applicant has been able to confirm that backflow within the channel is necessary to effectively induce cavitation.

[0060] Table 2: Cavitation pressure for various needle configurations

[0061]

[0062]

[0063] The volumetric flow rate through the needle is largely dependent on the upstream pressure and the needle diameter. Therefore, when lower pressure is required to generate cavitation, the volumetric flow rate is reduced. This is advantageous in practice because reducing the flow rate and / or pressure reduces the risk of any undesirable damage to the tooth caused by the jet due to high flow rates. Experiments have shown that the highest volumetric flow rate is achieved with the largest needle diameter of 25G, while the lowest flow rate is achieved with the smallest diameter of 34G. For a 25G needle with a length of 10 mm, a minimum cavitation pressure threshold of 6 bar was observed, accompanied by a volumetric flow rate of 72 ml / min. These results indicate that the cavitation threshold is significantly reduced within narrow, end-closed canals. Therefore, embodiments of the present invention can generate effective cavitation at lower upstream pressures accompanied by lower volumetric flow rates. This flow provides significant advantages: reduced pressure at the root canal tip and lower volumetric flow rates, both of which minimize the risk of tip extrusion.

[0064] Therefore, this result confirms that needle properties (such as diameter and length) have a significant impact on the threshold cavitation pressure. Furthermore, the experiment demonstrates that the role of the backflow fluid is crucial, increasing relative velocity and vortex formation, thereby significantly reducing the pressure required to generate cavitation.

[0065] The effect of needle length on the cavitation threshold is straightforward. A longer needle increases the pressure required for cavitation, which is thought to be consistent with the fact that a shorter needle will provide less flow resistance. However, in practical implementations, this typically means that the choice of needle length is a trade-off between an increase in threshold pressure and sufficient length to position the tip within the root canal for cavitation delivery and effective debridement.

[0066] Although the invention has been described above with reference to preferred embodiments, it should be understood that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

[0067] For example, some embodiments of the invention may include a heater 15 to increase the temperature of the flushing agent (thereby bringing the temperature closer to the phase boundary at a given pressure and further making cavitation more favorable). The heater 15 may be included as part of the base unit 10 or may be integrated into the handpiece. In some embodiments, the pump 14 or the base unit may include a pressure regulator.

[0068] Alternatively, or as an alternative to user interface 18, handheld device 20 may include a controller, such as a switch on the handheld device (or a switch associated with the handheld device, such as on a foot pedal). For example, a trigger may be set to activate the flow through the system.

[0069] Because embodiments of the invention enable the use of simple rinsing agents such as water or brine, it is understood that the embodiments can provide a variety of options in use. For example, the rinsing agent can be a low surface tension liquid or a high viscosity liquid. The rinsing agent may also include additives such as abrasive particles.

[0070] In some embodiments, the device may include a tube sensing system. For example, to ensure that liquid does not move across the tooth tip, embodiments may include a tip positioner to measure the distance to the tip and to assist the dentist in manipulating the device.

[0071] While the primary purpose of the pulp irrigation device of this embodiment may be root canal surgery, it is understood that the debridement and / or disinfection effects of cavitation flow can also be applied to other uses in dental practice. For example, the device can be used to remove plaque from the outside of the tooth or at the subgingival surface. The embodiment can also be used to drill through tooth tissue (dentin, enamel) or to cut soft tissue. The device can also be used to locate the entrance to the root canal.

Claims

1. A dental endodontic device, the device comprising: The flushing fluid supply section; A pump for delivering flushing fluid from the supply unit under pressure; A handheld device, in fluid communication with the pump, includes a needle extending from a rearward end near the handheld device to a forward end away from the handheld device. The needle has a lumen extending to an opening at the end for delivering fluid received from the pump into a tooth cavity. The opening at the end of the needle is a forward-facing axial opening, allowing the fluid to exit from the lumen in a forward axial flow. The needle has a length of at least 3 mm extending from its rear end to its distal end, an outer diameter of no more than 520 μm at the distal end, and at least the distal end of the needle has a needle specification size between 30 G and 34 G, such that the needle tip can be positioned within a portion of the root canal and that reflux can pass between the root canal and the needle; and The lumen at the end has a diameter of at least 50 μm, and the pump delivers the irrigating agent at a delivery pressure exceeding a threshold cavitation pressure, which provides the irrigating agent with an outlet velocity of at least 20 m / s at the needle tip, thereby causing backflow of the irrigating agent through the needle in the root canal to promote the formation of an inertial cavitation cloud in front of the needle tip and within the irrigating agent fluid in the root canal.

2. The dental pulp device according to claim 1, wherein, The delivery pressure is between 5 bar and 300 bar.

3. The pulp device according to claim 1 or 2, wherein, The length of the needle is between 10mm and 30mm.

4. The dental pulp device according to any one of the preceding claims, wherein, The flow rate of the flushing agent passing through the needle is less than 75 ml / min.

5. The dental pulp device according to any one of the preceding claims, wherein, The needle includes a distal portion and a proximal portion, the distal portion including a forward-opening end, the proximal portion being connected to the proximal end of the distal portion, and wherein the proximal portion has an increased diameter.

6. The dental pulp device according to any one of the preceding claims, wherein, The flushing fluid is a salt solution.

7. The dental pulp device according to any one of the preceding claims, wherein, The flushing fluid also includes disinfectant.

8. The dental pulp device according to any one of the preceding claims, wherein, The flushing fluid also includes abrasive particles.

9. The dental pulp device according to any one of the preceding claims, wherein, The device includes a regulator for controlling the delivery pressure.

10. The dental pulp device according to any one of the preceding claims, wherein, The device also includes a heater to control the temperature of the flushing fluid.

11. The dental pulp device according to any one of the preceding claims, wherein, The device also includes a pulse generator to pulse the supply of the flushing fluid.

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