This invention is an acoustic oral hygiene unit that uses acoustic energy to oscillate mild abrasive particles 17a in a water suspension 17 which is then directed in a low pressure stream onto the teeth. The oscillating abrasives scrub the teeth clean removing food particles, plaque, calculous, and other foreign material from tooth surfaces, interproximal areas, and tooth-gingiva interface more effectively than any previous technique. The relatively low power output and the basic design makes the invention safe and convenient for everyday use in the home without special training. This invention replaces all former means of home dental prophylaxis, and requires no augmentation to fulfill all requirements for daily oral hygienic care.

An insert for ultrasonic medical apparatus includes a transducer for generating ultrasonic vibrations and a treatment instrument actively coupled to the transducer to apply the ultrasonic vibrations developed by the transducer to a patient undergoing treatment. The treatment instrument is a slender needle and is provided with a bore along its longitudinal axis. The bore provides a flow path for a fluid which flows through it, through a bulge in the flowpath at one end of the treatment instrument, and out through an orifice in the bulge. The bulge or enlargement induces cavitation in the fluid which reinforces the ultrasonic vibrations.

Surgical instrument using ultrasonic energy which are to operate upon tissue including arrangements for shielding ultrasonic transducer probe to prevent energy from being radiated into unwanted areas which also include provisions for applying irrigation fluid and/or suction pressure to desired locations within the operating field.

The method and apparatus of the invention use ultrasonic energy in the form of mechanical vibrations transmitted by a tool member to close off small severed blood vessels, such as in humans, by the formation of closures at the terminal portions thereof, and stop what is called "oozes", that requires constant mopping or cleaning techniques during an operation. This tool member may be in the form of a knife ultrasonically vibrated to simultaneously sever and close off respective terminal portions of the severed blood vessels while performing surgical procedures. The tool member, of a proper configuration, may also join together layers of tissue, including the walls of unsevered blood vessels, and with respect to the latter is foreseen as replacing the "tying off" of arteries and veins currently necessary in surgery.

In a method for removal of dental plaque and caries in dentistry, there is applied to the teeth a high velocity pulsating jet stream of liquid possibly subjected also to ultrasonic vibration. The jet stream is pulsated, preferably with pulsations having a pressure-time wave form which includes, in each cycle, a period of lowered pressure or nil pressure sufficient for relaxation of the attacked material leading to mechanical fatiguing. The liquid may be neutral to the attacked material for a plaque removal, e.g., water, but for carie removal has a chemical action provided by an alkaline solution containing N-chloro and/or N-dichloro compounds resulting from interaction of certain hypohalites and amine compounds capable of removing plaque and caries both. The method is effective without the application of ultra-sonic vibrations, although their utilization with the aforesaid mechanical fatiguing pulsations is most effective. Utilization of ultra-sonic vibrations with harmonic pulsations is also effective. An embodiment of apparatus for application of the pulsating jet stream in dentistry incorporates pump means designed for providing the preferred pulsation wave forms. Preferably, the pump means is driven by a rotary cam co-acting with a cam follower which is adjustable to vary the duration of the pressure stroke during each cycle.