Single multi-function handpiece for dental instruments

A nonvibrating insert for use in a handpiece having a housing having a longitudinal bore therein adapted to receive a variety of dental tool inserts therein said handpiece having at least one inlet for the introduction of a gas therein, and means for establishing an alternating electromagnetic field in housing, said insert comprising a hollow tubular member integrally connected to a nozzle having two concentric tubes adapted for dispensing powder and liquid from said insert, said nozzle having a powder inlet extending therefrom parallel to said hollow tubular member and communicating with the inner tube of said two concentric tubes, the inner tube of said two concentric tubes having a tapered transition from one diameter to a smaller diameter, an outer tube of said two concentric tubes encircling said transition area wherein an inlet to said outer tube is provided near the tapered transition of said inner tube, said member comprising means for converting electromagnetic energy to heat electrostrictively.

A circuit for selecting a driving circuit comprising:

• (a) at least one drive coil for establishing an alternating electromagnetic field, and at least one feedback coil wherein said circuit has a voltage dependant on the nature of an insert placed within the windings of said drive coil and feedback coil
• (b) a frequency discriminator for detecting the frequency of the signal produced by the drive coil, and
• (c) a logic circuit adapted to detect different voltages and different frequencies in said circuit wherein said logic circuit comprises in series a buffer for transmitting a voltage signal to a comparator, a voltage comparator for comparing a voltage signal from said buffer with an internal reference, a frequency discriminator for recognizing and signaling the frequency of the circuit, means for algebraically summing the voltage of said drive coil and the resulting voltage in said feedback coil, and a logic array wherein input from said voltage comparator and frequency discriminator determines the value of the signal produced by said logic array depending on the values of the information received.