Dentistry – Apparatus – Having intra-oral dispensing means
Patent
1985-07-10
1987-09-29
Peshock, Robert
Dentistry
Apparatus
Having intra-oral dispensing means
433125, A61C 302
Patent
active
046966447
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an instrument for cleaning especally 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. Pat. Nos. 3,882,638 and 4,174,571. In practice, however, these known instruments have proved to give a very strong and inconvenient splashing. 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 considerable disadvantage which is overcome by the instrument according 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 stabilizes 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 handpiece (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 central 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 rotatable on or around the wall of the central conduit 12. The rotor ring 20 substantially 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 produces a suction effect sufficient to draw the abrasive powder through the supply tube 24 and to drive the powder further forward 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 provided 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.
Embodimen
REFERENCES:
patent: 2324250 (1943-07-01), Voerge
patent: 2669809 (1954-02-01), McGrath
patent: 4462803 (1984-07-01), Landgraf et al.
patent: 4482322 (1984-11-01), Hain et al.
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