US Patent 7159494 Torque limiting wrench for ultrasonic scaler tip insertion

A torque wrench for preventing transmission of torque in excess of a threshold level to avoid damage to replaceable scaler tips and hand pieces of ultrasonic dental instruments. The torque wrench has a housing with a core seated therein, with a cam mechanism or spring engagement between the core and the housing, such that the core may remain stationary when the housing is rotated passed the threshold level of torque. The core has an axial bore to receive a connecting shaft of a scaler tip, such that a working end and a functional shank of the scaler tip are received in a chamber of the housing, with the housing acting as an isolation cage for the scaler tip.