A disposable dental drill assembly is disclosed in this application and includes a housing in which is rotatably carried a rotor member including a turbine blade configuration and which is fixed to the end of a dental burr. The housing is formed with interlock means cooperating with complimentary means formed on a handle member whereby the drill assembly is easily removable from the handle member and can be replaced when the burr wears out. Both the housing and handle are formed with air passages and the handle is connected to a source of air pressure so that air flows over the turbine blades driving the rotor member and, accordingly, the burr. Because the drill assembly is disposable, the housing and the rotor member, including the turbine blade configuration, are made of a relatively inexpensive plastic material which can also be utilized for the handle member.

An endodontic or root canal sealing system and apparatus for practicing the system which includes an instrument for first placing a sealing or cementing substance onto the walls of the primary root canal as well as the auxiliary canals communicating therewith. The system also includes the utilization of gutta percha cones or "plugs" and an instrument for inserting said plugs into the canal following application of the sealing substance. The system also includes the utilization of an instrument either electrical, manual, or ultrasonic to heat, condense and/or pack the gutta percha cones or "plugs" into the main root canal and the auxiliary canals to thereby insure complete filling of a canal system. The system also includes the use of ultrasonically activated tips to place filling material into the cavity preparations or access openings in the crown of the tooth.

In one embodiment an ultrasonic transducer is provided in which the work tip is formed of a piece of tubular material and a substantial portion, or all, of the tip has a constantly diminishing cross-section approaching the end of the tip. The fluid for the work tip is delivered through the hollow tip to its end. Other embodiments of fluid delivery systems are also disclosed.

A transducer activated tool for contacting workpiece surfaces and directing fluid adjacent to the surfaces is disclosed. The tool may be ultrasonically activated by attachment to an insert that includes a magnetostrictive element. The tip includes distal surfaces shaped to contact the workpiece and additionally includes a fluid passageway internal to the tip that is bored generally along the centerline of the tip but is offset from the tip axis such that a discharge orifice is formed in the tip displaced from the distal tip end. The passageway is preferably angularly offset so that the discharge orifice is formed in the distal end of the tip about 2-8 mm from the distal end of the tip. The tip when shaped to conform to dental or tooth surfaces is particularly useful as a dental tool. In another embodiment the fluid passageway is eccentrically offset from the tip axis wherein the passageway is substantially parallel to the center axis but displaced therefrom preferably by about 0.1 to 0.5 mm. The tip end and fluid delivery passageway discharge orifice are located relative to each other such that fluid is provided to the workpiece or tip without the formation of excessive spray and without weakening the distal tip such that it is sufficiently strong to provide useful service in resisting flexural stresses and the like.

A transducer activated subgingival tool for contacting subgingival tooth surfaces and directing a fluid adjacent to said surfaces, wherein the tool has an activated tip having a fluid inlet end, a subgingival outlet end, a step in the surface of the outer wall of said tip between said inlet end and said subgingival outlet end, and a fluid passageway wall internal to the tip. The passageway wall is formed in the inlet end generally along the longitudinal center axis of the inlet end of the tip. In a preferred embodiment of the invention, the step intersects the passageway wall at the orifice edge.