Ultrasonic removal of dentine pins.

Replacement of pin-retained amalgam restorations is complicated by the loss of prime pin sites and remaining pin sites posing anatomical problems. Self-threading dentine pins can be removed with an ultrasonic handpiece, and the pin site reused with a large pin. Retention of replacement pins is similar to original pins. Pin removal after experimental placement takes a considerable time (< 15 min), but pin removal from extracted pin-restored teeth is much quicker (mean of 45 s). The reuse of primary pin sites allows uncomplicated replacement of pin-retained amalgams, and is a useful clinical technique.