Ultrasonic dental handpiece with rotary coupling

A dental handpiece assembly comprising:

• a handpiece tip connected to a handpiece;
• a handpiece housing of the handpiece enclosing a transducer assembly, the transducer assembly is in electrical communication with a secondary coil;
• a cable assembly comprising a cable and a primary coil said cable assembly configured to be connected to said handpiece housing through a swivel mechanism;
• a dynamic fluid interface between the cable assembly and the handpiece defined by a rotary connection between a primary bobbin of the primary coil and a water fitting of the handpiece, said water fitting disposed at an end of a secondary bobbin of the secondary coil, such that an arrangement of the dynamic fluid interface, the primary coil of the cable assembly and the secondary coil of the handpiece relative to each other produces the swivel mechanism so as to enable rotation of the primary coil relative to the secondary coil without seal leakage while unrestrictedly transmitting energy and lavage inside the handpiece, and
• wherein the handpiece is decoupled from a torsional load applied to it by the cable assembly and internal tubing and wires.