An ultrasonic medical instrument includes a probe shaft having a threaded coupling at a proximal end and an end effector or head at a distal end. The coupling is configured for operative attachment to a source of ultrasonic mechanical vibratory energy, while the head has an operative surface configured for engagement with organic tissues of a patient. The probe shaft, the coupling, and the head are made of a metal or metal alloy. At least one end-of-life indicator element is affixed to the probe shaft or head, the indicator element being made of a material that gradually disintegrates or degrades with use of the instrument so as to provide a visible indicator of degree of use and remaining useful life of the instrument.
