An ultrasonic surgical drill or drill bit includes a tubular member having a longitudinal axis of symmetry and a plurality of fins extending in longitudinal planes each containing the axis. In a surgical method utilizing the drill bit, one places a distal tip of the drill bit in contact with bone, presses the drill bit against the bone, and during that pressing of the drill bit, conducts ultrasonic vibrations into the drill bit. With the fins in contact with the bone, the drill bit is oscillated or angularly reciprocated about a longitudinal axis, so that the fins fragment bone material located between the fins.