Endodontic irrigating instrument

An endodontic irrigating instrument for irrigating a root canal of a tooth, which comprises:

• a handpiece having a proximal end and a distal end, said proximal end having an inlet for a compressed air and an inlet for an irrigating liquid under pressure and being so formed as to be coupled with a multiple-channel hose extending from a dental unit;
• a suction pump of the airjet type incorporated with said handpiece at the region adjacent said proximal end thereof, said suction pump having an air nozzle and and exhaust port;
• air passage means for supplying a flow of compressed air from said air inlet to said nozzle to create a zone of partial vacuum in said pump;
• a hollow aspiration needle mounted at an end thereof to said distal end of the handpiece, the other end thereof having an outer diameter substantially smaller than the inner diameter of the root canal to be irrigated;
• suction passage means for connecting said zone of partial vacuum with said aspiration needle to suck the irrigating liquid therein and to discharge it toward said exhaust port;
• a liquid ejection nozzle provided at said distal end of the handpiece adjacent said aspiration needle for supplying the irrigating liquid along said aspiration needle;
• liquid passage means for supplying the irrigating liquid under pressure from said liquid inlet to said ejection nozzle;
• and
• valve means for directing the compressed air to flow in the reverse direction through said suction passage toward said aspiration needle to permit backwashing of the aspiration needle, said valve meaning including a valve cylinder aligned with said exhaust port of said suction pump, said valve cylinder having an inlet port communicating with said air passage;
• a hollow movable spool forming said air nozzle of said suction pump and defining a circumferential annular space communicating with said inlet port in said valve cylinder, said movable spool having an inlet port communicating said annular space with the internal passage of said air nozzle, said movable spool being received slidably within said valve cylinder from a first position in which said air nozzle is away from said exhaust port to a second position in which annular space of said movable spool is in open communication with said zone of partial vacuum in said pump and in which said air nozzle closes said exhaust port, said movable spool being normally biased toward said first position;
• and means including a push rod for opening and closing said inlet port of said movable spool.