TOOTH CLEANING INSTRUMENT

Abstract: An instrument for cleaning teeth by blowing a powdered abrasive thereon includes a distal nozzle end (10) at which a central conduit (12) has an outlet portion (16) for supplying abrasive and drive gas therefor, and a surrounding annular passage (14) supplying water under pressure. The outlet portion (16) of the central conduit (12) continues beyond an outlet (18) of the annular passage, the outlet (18) being shaped as a restricted annular slot or throttle throat. Thus, a vacuum is created at the outlet portion (16) of the central conduit and this vacuum stabilizes the water jets and thereby counteracts splashes during the use of the instrument.

Description: TITLE: Tooth Cleaning Instrument The present invention relates to an instrument for cleaning especially teeth by blowing a powdered abrasive thereon and wherein, besides, the instrument is of the type stated in the opening clause of claim 1 . Instruments of this type are known from U .S. Patents Nos. 3,882,638 and 4,174,571 . In practice, however, these known instru¬ ments have proved to give a very strong and inconvenient splash- ing . Furthermore, it is recommended, or even prescribed, that the operator of the instrument should carry a face mask and gloves for protection against splashes. This is due to the fact that certain abrasives are rather strongly alkaline in aqueous solution . Also, there have been cases where the patients have had their contact lenses spoilt because of splashes of alkaline abrasive solutions. The strong splashing from the known instruments is a con¬ siderable disadvantage which is overcome by the instrument accord¬ ing to the invention which is characterized by the features stated in the characterizing clause of claim 1. Thus, the restricted annular slot or throat has the effect that a vaccum is created which stabi¬ lizes the water discharged and only very little splashing occurs. This stabilizing effect is further enhanced by the embodiment according to claim 2. The invention will now be described in further detail with references to the drawing which is a schematic presentation of an embodiment of the instrument of the invention . An instrument according to the invention comprises a hand- piece (not shown) having a distal nozzle portion 10 at which a centrally positioned conduit 12 has an outlet and supplies powdered abrasive mixed with drive gas. Around the central conduit 12 there is defined an annular passage 14 which supplies water under pressure. The outer or foremost portion 16 of the central conduit 12 continues beyond an outlet portion of the annular passage which is shaped as a restricted annular slot or throat 18. Hereby, a vacuum is created immediately at and around the outlet of the cen¬ tral conduit 12, and this vacuum stabilizes both the outflow of water and the outflow of air and abrasive powder. The embodiment shown further includes a rotor ring 20 which is located in the annular passage 14 upstream of the restricted outlet 18 thereof. The ring 20 is supported freely rotatabie on or around the wall of the central conduit 12. The rotor ring 20 sub- stantially fills out the flow sectional area of the annular passage 14 and, therefore, the water is forced through inclined nozzle passages 22 extending through the ring 20 in such a manner that the jets of water rotate the ring . Instead of the drilled passages 22 shown, inclined grooves extending in the periphery of the rotor ring may also be provided. In the embodiment shown the supply of abrasive powder takes place through a tube 24 inserted coaxially in the central conduit 12. Drive gas for the abrasive powder is supplied through an annular passage defined between the outside of the tube 24 and the inside of the central conduit 12. The discharge portion of the powder supply tube 24 is retracted relative to the outlet portion 16 of the central conduit 12 and, thereby, the drive gas thus supplied pro¬ duces a suction effect sufficient to draw the abrasive powder through the supply tube 24 and to drive the powder further for- ward and out of the outlet portion 16 of the central conduit 12. In the embodiment shown the inlet end of the powder supply tube 24 is connected with a chamber 26 containing or receiving abrasive powder. In a specific embodiment, the chamber 26 collects abrasive powder produced by a grinding disc 28 rotating in a closed housing 30. In the side of the housing an opening is pro¬ vided in which a cylindrical bar 32 of abrasive may be inserted and retained relative to the grinding disc. The bar 32 may preferably be inserted in a cylindrical guide cylinder 34 comprising a slidable piston 36. When pressurized gas is supplied, the piston 36 is capable of continuously keeping the bar 32 in contact with the grinding disc 28 at a constant pressure of contact. Embodiments as that shown in the drawing are particularly suited for use with water soluble abrasives, partly because no significant splashing occurs during the use of the instrument, and - partly because of the construction of the supply system for the powder. Thus, powder of water-soluble abrasives strongly tends to lump and form coatings internally in passages, if the powder has the possibility to absorb humidity. In known instruments for use with water soluble abrasives it has thus been necessary to constantly keep the powder in motion in a store container by means of pressurized gas. Such provisions are not required in the instrument of the invention wherein the powder is not produced until immediately before use. Besides, the entire powder tube system may be blown empty for powder just by closing the outlet 16 of the central conduit 12 while drive gas is still being supplied. OMPI IPO

Claims: PATENT CLAIMS 1 . An instrument for cleaning, especially tooth cleaning, by blowing a powdered abrasive thereon, said instrument comprising a handpϊece having a distal nozzle portion (10) at which a centrally positioned conduit (12) has an outlet portion (16) for supplying abrasive and drive gas therefor, and a surrounding annular passage (14) supplying water under pressure, CHARCTERIZED in that the outlet portion (16) of the central conduit (12) continues beyond the outlet of the annular passage (14), said outlet being shaped as a restricted annular slot or throttle throat (18). 2. The instrument of claim 1 , CHARCTERIZED in that a freely rotatabie rotor ring (20) is positioned upstream of said restricted outlet (18) of the annular passage (14), said rotor ring substan¬ tially filling out the flow sectional area of the annular passage (14) and being provided with a series of inclined nozzle passages (22) extending through the rotor ring in such a way that the water jets produced thereby rotate the rotor ring . 3. The instrument of claims 1 or 2, CHARCTERIZED in that the central conduit (12) comprises a tube (24) positioned centrally therein and which supplies abrasive, the discharge end thereof being retracted relative to the outlet portion (16) of the central conduit (12), and that the drive gas is supplied through an annular passage defined by the outer side of the tube (24) and the inner side of the central conduit (12). 4. The instrument of claim 3, CHARCTERIZED in that the inlet end of the abrasive supply tube (24) is connected with a chamber (26) which is adapted to contain or receive abrasive powder. 5. The instrument of claim 4, CHARCTERIZED in that the chamber (26) collects abrasive powder produced by a rotating grinding disc (28) . A38d

Inventors: GOOF SVEN KARL LENNART, GOOF, SVEN, KARL, LENNART
Applicants: GOOF SVEN KARL LENNART, GOOF, SVEN, KARL, LENNART
Application year: 1984
Main classification: A61C17
IPC codes: A61C3, A61C17