Abstract: An ultrasonic root end retro-preparation endodontic apical surgical instrument. The instrument has a double-angled shape with a length of between about 1-2 in (2.5-5.1 mm), and is made of a metal which safely and effectively propagates ultrasonic energy from a base segment to a bent distal tip with a length of between about 0.08-0.15 in (0.20-0.38 mm). The instrument includes a swivel segment that permits rotation of the bent distal tip of up to 360°. By allowing the bent distal tip to be swiveled, the instrument may be used for all quadrants, anterior and posterior teeth without switching out the instrument for another one.