(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY(PCT)
`
`(19) World Intellectual Property
`Organization
`International Bureau
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`(43) International Publication Date
`21 July 2005 (21.07.2005)
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`
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`(10) International Publication Number
`WO 2005/065032 A2
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`(1)
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`(21)
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`(22)
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`(25)
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`(26)
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`(30)
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`(71)
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`(72)
`(75)
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`(74)
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`International Patent Classification:
`
`Notclassified
`
`International Application Number:
`PCT/IL2005/000017
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`International Filing Date:
`
`5 January 2005 (05.01.2005)
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`Filing Language:
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`Publication Language:
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`Priority Data:
`159783
`
`English
`
`English
`
`8 January 2004 (08.01.2004)
`
`IL
`
`except US):
`(for all designated States
`Applicant
`TAVTECH LTD.
`[ILAL]; P.O. Box 1167 City Gate
`Building56, Haatzmaut Street, 56000 Ychud (IL).
`
`Inventor; and
`Inventor/Applicant (for US only): TAVGER, Michael
`[HILAL]; 4 Alonim Street, 12900 Katzrin CL).
`
`Agent: JEREATY M. BEN-DAVID & CO. LTD.,; P.O.
`Box 45087, Har Hotzvim Hi-Tech Park, 91450 Jerusalem
`(IL).
`
`(81) Designated States (unless otherwise indicated, for every
`kind of national protection available): AE, AG, AL, AM,
`AT, AU, AZ, BA, BB, BG, BR, BW, BY, BZ, CA, CH, CN,
`CO, CR, CU, CZ, DE, DK, DM, DZ, EC, EE, EG, ES, FI,
`GB, GD, GE, GH, GM, HR, HU,ID,IL, IN, IS, JP, KE,
`KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD,
`MG, MK, MN, MW, MX, MZ, NA, NI, NO, NZ, OM,PG,
`PH,PL, PT, RO, RU, SC, SD, SE, SG, SK, SL, SY, TJ, TM,
`TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, YU, ZA, ZM,
`ZW.
`
`(84) Designated States (unless otherwise indicated, for every
`kind of regional protection available): ARIPO (BW, GH,
`GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM,
`ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM),
`European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI,
`FR, GB, GR, HU,IE,IS, IT, LT, LU, MC, NL, PL, PT, RO,
`SE, SI, SK, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN,
`GQ, GW, ML, MR, NE, SN, TD, TG).
`
`Published:
`
`without international search report and to be republished
`upon receipt ofthat report
`
`{Continued on next page]
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`(54) Title: A HIGH VELOCITY LIQUID-GAS MIST TISSUE ABRASION DEVICE
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`(57) Abstract: The present invention relates to a device for abrading or cleansing tissue. The device includes a gas inlet port con-
`nected to a pressurized gas source, and a liquid inlet port connected to a pressurized liquid source. There is, additionally, a mist
`jet delivery nozzle arrangement, which includes one or more gas discharge nozzles arranged to receive a flow of pressurized gas
`from the gas inlet port and configured to accelerate the flow of gas so as to discharge it at an elevated velocity. Further, there are
`one or more liquid discharge nozzles arranged to receive a flow of liquid from the liquid inlet port and operative to discharge the
`flow of liquid into the elevated velocity flow of gas, thereby to similarly accelerate the velocity of the discharged liquid as a mist of
`accelerated droplets.
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`WO2005/065032A2IIIINIENNINTINIMINTIITTIMINIENNIMM
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`WO 2005/065032 A2_IIMINNINNUIUINTAIT TTT ANIA RIKIUNG MIT CAM Tt
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`For two-letter codes and other abbreviations, refer to the "Guid-
`ance Notes on Codes and Abbreviations" appearing at the begin-
`ning of each regular issue of the PCT Gazette.
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`WO 2005/065032
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`PCT/IL2005/000017
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`A HIGH VELOCITY LIQUID-GAS MIST TISSUE ABRASION DEVICE
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`FIELD OF THE INVENTION
`
`The present invention relates, generally to a device for tissue abrasion, and, more
`specifically, to a device for applying a high velocity liquid-gas mist for dermal abrasion and
`skin peeling.
`
`BACKGROUND OF THE INVENTION
`
`It is known in the art to provide apparatus for dermal abrasion and the cleansing of
`exposed in vivo tissue. There are a multiplicity of applications to both humans and animals
`during surgical procedures where the removal from the tissue surface of solid contaminants,
`such as fibers, dust, sand particles, and the like, as well as organic matter, such as puss, fats,
`
`and others, is necessary.
`
`In addition, such cleansing is necessary in preparation prior to and/or subsequent to
`treatment for dental conditions such as gingivitis, caused by the long-term effects of plaque
`deposits. Unremoved plaque mineralizes into a hard deposit called calculus (tartar) that
`becomestrapped at the base ofthe tooth. It is also necessary to remove the toxins produced by
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`the bacteria.
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`Organic matter including the outer dermal layer tends to bond to tissue much more
`strongly than non-organic matter, and is generally more difficult to remove. Accordingly,
`while non-organic matter is removable from the tissue by meansofa liquid stream,it is often
`not possible to remove some organic matter in this way. More specifically, and most
`problematic, are those particles which are smaller than the thickness of the boundary layer of
`the fluid stream which is formed on the tissue surface during irrigation with a liquid such as
`water. The boundary layer is characterized by having a fluid velocity which reduces sharply
`adjacentto the flow surface, and whichis virtually zero at the surface.
`
`The smallest particles located in the boundary layer exhibit a drag resistance of a
`magnitude sufficient for these particles to remain attached to the surface and to resist being
`swept away by the fluid stream, evenif this has an overall very high velocity.
`
`A number of cleansing devices and systems have been developed to improve the
`cleansing of a variety of surfaces. To attempt solve this problem, there have been developed a
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`number of prior art devices such as disclosed in USP 3,982,965, 4,350,158, 4,681,264,
`4,982,730, 5,046,486, 5,551,909, 6,199,773, 6,203,406, 6,454,871 and GB1008503. These
`devices operate on the basis of providing a liquid stream with a reduced boundary layer
`thickness employing fluid and air nozzle assemblies, a high velocity aerosol of at
`least
`partially frozen particles, and pulsed jets of liquid sprayed on to a metal surface in order to
`sweep away small particles. These devices, however, generally have
`complicated
`constructions, use very large quantities of liquid, and have been found to provide only a small
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`improvement over non-pulsed spray devices.
`
`Referring now to US 5,730,806 entitled “Gas-liquid supersonic cleaning and cleaning
`verification spray system” to Caimi, et al. on March 24, 1998, there is disclosed a gas-liquid
`cleaning spray system which employs one or more converging-diverging nozzles to accelerate
`a gas-liquid mixture to a supersonic velocity for cleaning various types of articles, such as
`
`mechanical, electrical and fluid components.
`
`Referring now to US 6,293,498 and US6,360,992 entitled “Hybrid deicing system and
`method of operation” to Stanko, et al. on September 25, 2001 and March 26, 2002
`respectively, there is disclosed an invention which overcomes the disadvantage of the prior
`systems and produces a high velocity specially formed and constituted pressure aerodynamic
`stream system forefficiently and effectively removing ice from an aircraft.
`
`Referring now to US 5,100,412 entitled “Apparatus for making micro-abrasions,
`particularly on human tissue or on hides” to Rosso on March 31, 1992 there is disclosed
`apparatus for making micro-abrasions, particularly on human tissue, which includes a handle
`having an aperture which is intended to be positioned on the surface to be treated, and a
`nipple device for the metered supply of reducing substances in a pneumatic carrier to the
`aperture of the handle. The supply device comprises only a vacuum source connected to the
`handle to draw the reducing substances towards the aperture of the handle. A collector device
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`is provided for collecting the used substances for disposal.
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`Referring now to US 5,207,234 entitled “Method for making micro-abrasions on
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`human tissue” to Rosso on May 4, 1993, there is disclosed a method for making micro-
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`abrasions on human tissue. The method includes placing a handle having an open chamber
`therein on humantissue to close the chamber, applying suction to the chamberto sealingly
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`engage the periphery of the chamber with the human tissue and partially sucking the human
`tissue into said chamber. This induces the flow ofair into the chamber by the removal ofair
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`from the chamber by suction while restricting entry of ambient air from the surrounding
`atmosphere into the chamber around the periphery of the chamber, entraining a reducing
`substance in said flow ofair prior to entry of the flow ofair into the chamber. This directs the
`reducing substance entering the chamber against the human tissue at an angle less than 90
`degrees, entraining used reducing substances and abraded tissue in the flow of air being
`removed from the chamber by suction and collecting used reducing substances and abraded
`tissue in a manner to prevent reuse of the reducing substances during continued application of
`
`a vacuum to the chamber.
`
`Referring now to US 5,810,842 entitled “Equipment for microdermoabrasion through
`a flow of an air/reducing substances mix” to Di Fiore, et al. on September 22, 1998, there is
`disclosed a device for microdermoabrasion using a flow of a mixture of air and reducing
`
`substances. The device comprises a casing with a vacuum pump and a compressor at an
`interior of the casing. The device further comprises a control footswitch for actuating the
`compressor, a mixing bulb anda collecting bulb at an exterior of the casing, and a handpiece
`extending between the mixing bulb and the collecting bulb. The mixing bulb contains a
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`mixture of air and reducing substances.
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`Further, there have been developed a multiplicity of dental cleaning devices, which
`operate to clean teeth, cavities and spaces between the teeth. Some such devices also address
`the problem of gingivitis. Included amongst such devices are USP 5,013,241, 5,203,698,
`5,273,428, 5,387,182, 5,667,483, 6,120,755, 6,224,378, 6,497,572 and DE19654098,
`
`FR2654331, FR2599244, DE3726349.
`
`Referring now to Israel Patent No. 118801 entitled “Apparatus and Method for
`Cleansing Tissue” to M. Tavger on December 16, 2001,
`there is disclosed apparatus
`employing liquid and gas as working fluids for cleansing living tissue, which includes: a
`container for a sterile liquid; a fluid delivery head having a liquid entry port and a gas entry
`port, fluid outlet apparatus, and valve apparatus located between the entry ports and the fluid
`outlet apparatus and for selectably permitting respective liquid and gas flows from the entry
`ports to the fluid outlet apparatus; liquid conduit apparatus extending between a liquid inlet
`located within the container and a liquid outlet connected to the liquid entry port of the
`delivery head; gas conduit apparatus extending between a gas inlet and a gas outlet, wherein
`the gas inlet is connected to a source of pressurized gas and the gas outlet is connected to the
`gas entry port of the delivery head, and wherein the gas conduit apparatus is connected to the
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`container via an intermediate outlet port; and apparatus for selectably exposing the source of
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`sterile liquid to a flow of pressurized gas flowing from the gas inlet to the gas outlet and into
`the gas entry port of the fluid delivery head, thereby to pumpthesterile liquid along the liquid
`conduit apparatus, from the inlet to the outlet, and into the liquid entry port of the fluid
`delivery head, wherein the fluid outlet apparatus comprises a gas-liquid combining member
`arranged to receive the gas and liquid flows and to combine them into a gas-liquid outflow
`which is operative to exit the apparatus through the fluid outlet in the form ofasterile liquid
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`mist suspended in a high velocity gas stream.
`
`Referring now to Israel Patent No. 122016 entitled “Apparatus for Dermal Abrasion”
`to M. Tavger on December 16, 2001, there is disclosed a method of dermal abrasion, which
`includes exposing a source ofsterile liquid to a flow of pressurized gas, thereby causing a
`pumped supply thereof into a fluid delivery head; supplying the pressurized gas to the fluid
`delivery head; and combining the gas and liquid supplied to the delivery head; this fluid
`delivery head having a fluid outlet with a predetermined internal diameter, so as to provide a
`gas-liquid outflow in the formofa sterile liquid mist jet suspended in a high velocity gas
`stream; and exposing to the mist jet, at a preselected distance from the fluid outlet, a portion
`of the skin surface sought to be abraded, thereby separating therefrom at least a portion of the
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`epidermis and removing therefrom the resulting tissue debris.
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`Many of the dermal abrasion and cleansing devices disclosed hereinabove have a
`specific drawback, when employed for tissue abrasion or skin peeling. The relatively high
`flow rate of liquid employed by the above-mentioned cleansing devices reduces the cleansing
`and scouring effect as a result of the development of a virtually stagnant boundary layer over
`the surface to be cleaned. There is a need in the art, notably in relation to dermal abrasion and
`to cleansing tissue surfaces or cavities,
`to avoid boundary layer formation during the
`cleansing process by utilizing a minimal flow ofliquid.
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`SUMMARYOF THE INVENTION
`
`The present invention aims to provide a device for the abrasion oftissue, using a
`relatively low rate of flow of cleansing liquid formed as a mist of droplets carried in a high
`velocity gas. The mist droplets are driven against the tissue surface, mass or cavity to be
`abraded at a very high velocity, thereby scouring the tissue surface. Further, the low rate of
`flow of liquid effectively ensures the formationof virtually no liquid boundary layer, thereby
`maximizing the abrading effect.
`
`According to a preferred embodiment of the present invention there is provided a
`device for abrading tissue, which includes:
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`a gas inlet port connected to a pressurized gas source;
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`a liquid inlet port connected to a pressurized liquid source; and
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`a mist jet delivery nozzle arrangement, which
`includes one or more gas discharge nozzles arranged to receive a flow of pressurized gas from
`the gas inlet port and configured to accelerate the flow of gas so as to discharge it at an
`elevated velocity, and further includes one or more liquid discharge nozzles arranged to
`receive a flow ofliquid fromthe liquid inlet port and operative to discharge the flow of liquid
`into the elevated velocity flow of gas, thereby to similarly accelerate the velocity of the
`discharged liquid as a mist of accelerated droplets.
`
`According to another preferred embodimentof the present invention there is provided
`a device for abrading tissue, which includes a gas inlet port connected to a pressurized gas
`source, a liquid inlet port connected to a pressurized liquid source, a mist jet delivery nozzle
`arrangement and a suction nozzle arrangement. The device further comprises suction means,
`which includes a suction conduit disposed in operative association with respect to the mist jet
`delivery nozzle arrangement and including one or more suction ports. The device,
`additionally, comprises an atmospheric air inlet conduit having at least one air inlet port
`disposed in operative association with respect to the suction conduit and to the mist jet
`delivery nozzle arrangement, and moreover meansfor applying a suction force to the suction
`conduit, thereby to cause suctioning from one or more suction ports of liquid and abraded
`tissue particles in the vicinity of the mist jet delivery nozzle arrangement.
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`In accordance with an embodiment of the present
`
`invention,
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`the device further
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`comprises suction means, which includes a suction conduit disposed in operative association
`with respect to the mist jet delivery nozzle arrangement and including one or more suction
`ports. The device additionally comprises an atmospheric air inlet conduit having one or more
`air inlet ports disposed in operative association with respect to the suction conduit and to the
`mist jet delivery nozzle arrangement, and moreover meansfor applying a suction force to the
`suction conduit, thereby to cause suctioning from the one or more suction ports of liquid and
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`abradedtissue particles in the vicinity of the mist jet delivery nozzle arrangement.
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`In accordance with another embodiment of the present invention, gas is supplied from
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`the pressurized gas source at a pressure in the range of 40-150 p.s.i. and liquid is supplied
`from the pressurized liquid source at a pressure in the range of 0 to 5 p.s.1.
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`In accordance with one other embodiment of the present invention, the gas supplied
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`from the pressurized gas source includes one or more ofair, oxygen, carbon dioxide and
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`nitrogen.
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`In accordance with a further embodimentof the present invention, the gas discharged
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`from the one or more gas discharge nozzles is accelerated to a velocity in the range of sub-
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`sonic to supersonic velocity.
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`In accordance with an additional embodiment of the present invention, the mist jet
`delivery nozzle arrangement includes at least two gas discharge nozzlesor at least two liquid
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`discharge nozzles.
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`In accordance with one other embodiment of the present invention, the one or more
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`liquid discharge nozzles are disposed substantially concentric and within the one or more gas
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`discharge nozzles.
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`In accordance with an additional embodiment of the present invention, the one or
`more gas discharge nozzles are devices configured to have a converging portion, a throat
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`portion and a diverging portion.
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`In accordance with an embodiment of the present invention, the device is configured
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`to be used while being held in one hand.
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`In accordance with one other embodiment of the present invention, the flow of gas
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`entering the one or more gas discharge nozzles is at a pressure of a first magnitude, and the
`one or more gas discharge nozzles are operative to cause a pressure drop in the gas flow
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`therethrough such that the pressure of the gas discharged from the one or more gas discharge
`nozzles is of a second magnitude, wherein the first magnitude is at least twice the second
`magnitude, so as to cause a shock wavein the gas and liquid flow downstream of the one or
`more gas discharge nozzles and the one or more liquid discharge nozzles so as to cause
`atomizing of the liquid discharged from the one or more liquid discharge nozzles into a high
`velocity mist of droplets,
`thereby to form a mist of droplets suspended in the flow of
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`discharged high velocity gas.
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`According to another preferred embodimentof the present invention, there is provided
`a system for abrading tissue. The system includes a pressurized gas source, a pressurized
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`liquid source and a device which includes:
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`a gas inlet port connected to the pressurized gas source;
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`a liquid inlet port connectedto the pressurized liquid source; and
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`a mist jet delivery nozzle arrangement including one or more gas discharge nozzles
`arranged to receive a flow of pressurized gas from the gas inlet port and configured to
`accelerate the flow of gas so as to discharge it at an elevated velocity. The device further
`includes one or more liquid discharge nozzles arranged to receive a flow of liquid from
`the liquid inlet port and operative to discharge the flow of liquid into the elevated
`velocity flow of gas, thereby to similarly accelerate the velocity of the discharged liquid
`as amist of accelerated droplets.
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`invention the system further
`In accordance with an embodiment of the present
`includes a suction conduit disposed in operative association with respect to the mist jet
`delivery nozzle arrangement and including one or more suction ports and, also, an
`atmospheric air inlet conduit having one or more air inlet ports disposed in operative
`association with respect to the suction conduit and to the mist jet delivery nozzle arrangement.
`The system additionally includes means for applying a suction force to the suction conduit,
`thereby to cause suctioning from one or more suction ports of liquid and abraded tissue
`particles in the vicinity of the mist jet delivery nozzle arrangement.
`
`In accordance with another embodiment of the present invention, gas is supplied from
`the pressurized gas source at a pressure in the range of 40-150 p.s.i. and liquid is supplied
`from the pressurized liquid source at a pressure in the range of 0 to 5 p.s.i.
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`In accordance with one other embodimentof the present invention, the gas supplied
`from the pressurized gas source includes one or more of air, oxygen, carbon dioxide and
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`nitrogen.
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`In accordance with another embodiment of the present invention, the gas discharged
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`from the one or more gas discharge nozzles is accelerated to a velocity in the range of sub-
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`sonic to supersonic velocity.
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`In accordance with an added embodiment of the present invention, the mist jet
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`delivery nozzle arrangement includes at least two gas discharge nozzles. In accordance with
`another embodiment of the present invention,
`the mist jet delivery nozzle arrangement
`includes at least two liquid discharge nozzles. In accordance with an additional embodiment
`of the present invention, the one or more liquid discharge nozzles are disposed substantially
`concentric and within the one or more gas discharge nozzles.
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`In accordance with one other embodiment of the present invention, the one or more
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`gas discharge nozzles are devices each configured to have a converging portion, a throat
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`portion and a divergingportion.
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`In accordance with one other embodiment of the present invention, the device is
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`configured to be used while being held in one hand.
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`In accordance with a further embodiment of the present invention, the flow of gas
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`entering the one or more gas discharge nozzles is at a pressure of a first magnitude, and the
`one or more gas discharge nozzles are operative to cause a pressure drop in the gas flow
`therethrough such that the pressure of the gas discharged from the one or more gas discharge
`nozzles is of a second magnitude, wherein the first magnitude is at least twice the second
`magnitude, so as to cause a shock wavein the gas and liquid flow downstream ofthe one or
`more gas discharge nozzles and the one or more liquid discharge nozzles so as to cause
`atomizing of the liquid discharged from the one or more liquid discharge nozzles into a high
`velocity mist of droplets, thereby to form a mist of droplets suspended in the flow of
`discharged high velocity gas.
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`Furthermore, there is provided a method for abrading tissue by application of a high
`velocity liquid-gas mist thereto. The method includes a step of accelerating a flow of gas
`through one or more gas nozzles so as to provide a gas discharge flow at an elevated velocity,
`another step of introducing into the elevated velocity gas discharge flow a flow of liquid,
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`thereby to fragment the liquid into a mist of droplets, and to accelerate the mist to an
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`accelerated velocity similar to the velocity of the gas discharge flow, and a further step of
`exposing a desired tissue mass to the accelerated droplet mist.
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`In accordance with an embodiment of the present invention, the method includes an
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`additional step of applying a suction force to a suction conduit, thereby to cause suctioning
`from at least one suction port of liquid and abraded tissue particles in the vicinity of the gas
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`and mist discharge flow.
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`In accordance with one other embodiment of the present
`
`invention,
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`the step of
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`accelerating a flow of gas includes accelerating the flow of gas to a velocity in the range of
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`sub-sonic to supersonic velocity.
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`In accordance with another embodiment of the present
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`invention,
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`the step of
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`accelerating a flow of gas includes accelerating the flow of gas to a velocity in the range of
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`sonic to supersonic velocity.
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`In accordance with an additional embodiment of the present invention, the step of
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`accelerating a flow of gas includes accelerating a gas selected from the group of gases
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`including one or moreofair, oxygen, nitrogen and carbon dioxide.
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`In accordance with a further embodiment of the present
`invention,
`the step of
`introducing into the elevated velocity gas discharge flow a flow ofliquid, includes the flow of
`gas entering the one or more gas discharge nozzles being at a pressure of a first magnitude,
`and the one or more gas discharge nozzles being operative to cause a pressure drop in the gas
`flow therethrough such that the pressure of the gas discharged from the one or more gas
`discharge nozzles is of a second magnitude, wherein the first magnitude is at least twice the
`second magnitude, thereby causing a shock wave in the gas and liquid flow downstream of
`the one or more gas discharge nozzles and the one or more liquid discharge nozzles so as to
`cause atomizing of the liquid discharged from the one or more liquid discharge nozzles into a
`high velocity mist of droplets, thereby forming a mist of droplets suspended in the flow of
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`discharged highvelocity gas.
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`In accordance with one other embodiment of the present
`invention,
`the step of
`exposing a desired tissue mass to the accelerated droplet mist includes holding the device in
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`one hand.
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`In accordance with an embodiment of the present invention, the step of exposing a
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`desired tissue mass includes cleansing the tissue mass thereby to remove contaminants from
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`the tissue mass.
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`In accordance with another embodiment of the present invention, the step of exposing
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`a desired tissue mass includes dispersing accumulated liquid from the tissue mass by the flow
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`of high velocity gas.
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`In accordance with a further embodimentof the present invention, the step of exposing
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`a desired tissue mass includes cleansing away and destroying residual anaerobic organisms
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`using a sterile liquid mist in a flow of oxygen gas.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`The present invention will be more fully understood and its features and advantages
`will become apparent to those skilled in the art by reference to the ensuing description, taken
`in conjunction with the accompanying drawings, in which:
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`Figure 1 is a perspective view of a tissue abrasion device, constructed and operative
`constructed and operative in accordance with a preferred embodiment of the present
`
`invention;
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`Figure 2 is a schematic side view of the device of Fig. 1;
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`Figure 3 and 4 are enlarged schematic and graphical representations, respectively, of a
`delivery nozzle arrangementof the device seen in Figures 1 and 2;
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`Figure 5 is a schematic view of a flow of mist droplets discharging from the delivery
`nozzle arrangement as seen in Figure 4 against a surface to be abraded;
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`Figure 6 is a schematic view of a flow of mist droplets discharging from the delivery
`nozzle arrangement seen in Figure 4, into a periodontal pocket;
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`Figure 7 is a schematic view of a nozzle arrangement, constructed and operative in
`accordance with an alternative embodimentof the present invention, having multiple gas and
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`liquid discharge nozzles;
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`Figure 8 and9illustrate the effect of a boundary layer formed on a surface being
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`abraded;
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`Figures 10 is a cross-sectional partial plan view of a tissue abrasion device including a
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`suction means in accordance with another embodimentof the present invention;
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`Figure 11 is a perspective cut-away partial view of the tissue abrasion device including
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`a suction means; and
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`Figure 12 is a cross-sectional partial elevation view of a tissue abrasion device
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`including a suction means.
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`DETAILED DESCRIPTION OF THE INVENTION
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`The present invention relates to a device for abrading tissue by directing thereat a
`liquid-gas mist of droplets at a high velocity generally within the range of sub-sonic to super-
`sonic. To achieve this, gas is discharged from a converging-diverging gas nozzle configured to
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`accelerate the flow of gas so as to discharge it at an elevated velocity. A low rate of flow of
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`liquid is discharged into the elevated velocity flow of gas, thereby to similarly accelerate the
`velocity of the discharged liquid as a mist of accelerated droplets. The volumetric rate of flow
`of liquid from the device is relatively low, thereby minimizing the formation of a virtually
`stagnant liquid boundary layer onthe surface of the tissue to be abraded.
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`With reference to Figures 1 and 2, there is seen, according to a preferred embodiment
`of the present invention, a device referenced generally 100 for applying a high velocity liquid-
`gas mist to tissue thereby to cause abrasion thereof. Alternatively, the velocity of the mist may
`be regulated so as to merely provide cleansing or debradement of the tissue. Device 100
`includes a housing portion referenced 102 having a generally tubular configuration, and
`having proximal and distal ends, referenced generally 104 and 106 respectively. A gas inlet
`port referenced 108 anda liquid inlet port referenced 110 are provided at proximal end 104,
`and a mist jet delivery nozzle arrangement referenced generally 112, is provided at distal end
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`106.
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`Referring now to Figures 3 and 4 in conjunction with Figure 2, there are seen
`schematic cross-sectional views of nozzle arrangement 112 of device 100. Nozzle
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`atrangement 112 includes a gas discharge nozzle referenced generally 114 and, disposed
`generally concentrically there-within,is a liquid discharge nozzle referenced 116. Liquid inlet
`port 110 is connected in fluid flow communication with liquid discharge nozzle 116 by means
`of a liquid communication tube referenced 118, disposed generally concentrically within
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`tubular housing portion 102.
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`PCT/IL2005/000017
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`Pressurized gas supplied from a pressurized gas source (not shown) enters device 100
`through gas inlet port 108 and passes along and within tubular housing portion 102 as
`indicated by arrows 134, so as to discharge through gas discharge nozzle 114. Gas discharge
`nozzle 114 is generally configured having,
`in flow succession, a converging portion
`referenced 120, a throat portion referenced 122 and a diverging discharge portion referenced
`124. The pressurized gas discharging from nozzle 114, as indicated by arrows 126, undergoes
`a rapid and substantial reduction in pressure to atmospheric pressure and a substantial
`acceleration to a high velocity, within the range of subsonic to supersonic velocity and
`specifically to a supersonic velocity. Gas discharge nozzle 114 is configured such that the
`discharging gas has a cone angle of less than 10 degrees, that is, providing a substantially
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`parallel gas flow.
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`Liquid from a pressurized liquid source (not shown) enters device 100 through liquid
`inlet port 110 and passes, as indicated by arrow 132, through liquid communication tube 118.
`In turn, at distal end 106, liquid is discharged through an opening referenced 128 in the distal
`end of liquid discharge nozzle 116 into the discharging flow 126 of gas, the liquid flow being
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`indicated by arrow 130.
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`It will be appreciated by personsskilled in the art that, as the pressurized discharging
`gas emerges 126 from gas discharge nozzle 114 into the atmosphere, it undergoes a rapid drop
`in pressure to atmospheric pressure. The sudden pressure drop results in a substantial
`acceleration of the velocity of the discharging gas flow that approximates or even exceeds the
`velocity of sound and the production of a shock wave. The effect of the shock waveis to
`atomize the liquid discharging from liquid discharge nozzle 116 into the flow of gas as a mist
`of liquid droplets 130, such that there is obtained a relatively narrow jet of liquid droplets in a
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`high velocity gas flow 126.
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`Further, by way of example, the proportion of liquid flow to gas flow is extremely low
`due to the relatively high gas pressure of about 100 p.s.i. and low liquid pressure of about 2
`p.s.i., as well as the relatively large internal diameter of gas discharge nozzle 114 (about 0.8
`mm) compared to a small internal diameter (about 0.09 mm) of liquid discharge nozzle 130.
`Consequently,
`little liquid tends to accumulate at
`the site to be abraded or scoured.
`Furthermore, the relatively high gas flow hasthe effect of dispersing any accumulated liquid.
`When using a jet utilizing only liquid for cleansing, the liquid tends to accumulate on the
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`tissue surface resulting in formation of a virtually stagnant liquid boundary layer close to and
`in contact