| 摘要 |
PCT No. PCT/DK84/00106 Sec. 371 Date Jul. 10, 1985 Sec. 102(e) Date Jul. 10, 1985 PCT Filed Nov. 12, 1984 PCT Pub. No. WO85/02107 PCT Pub. Date May 23, 1985.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.
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