Orthograde ultrasonic retrieval of root canal obstructions.

An eclectic array of objects are introduced into root canals. Some of these items such as obturation materials or posts are inserted intentionally while many others are introduced inadvertently. Retrieval of intracanaJ obstructions may be difficult but essential if nonsurgical retreatment is necessary. Fortunately, a number of ingenious instruments and techniques have evolved which enable successful orthograde retrieval of foreign articles. Unintentional iatrogenic inclusion of various articles into root canals has been reported. These include absorbent points (1), burs (2, 3), files (4-6), glass beads (7), and amalgam or gold filings (3, 8). In addition, patients may block root canals in teeth which have been left open to drain. Grossman (1) discovered small nails and an indelible ink pencil tip in canals. He also reported finding a toothpick in a canal and a tomato seed in the penapex. (The seed sprouted upon its removal!) Zillich and Pickens (9) retrieved a hat pin and Tumer (10) removed a dress maker's pin which had broken in a tooth. Nemst (11 ), Harris (12), and Lamster and Barenic (13) described finding needles and pins, pencil lead, and other metal objects in canals. Attempted removal of these foreign objects has spawned the development of several devices, instruments, and techniques which aid in the retrieval of canal obstructions. Feldman et al. (6) described techniques that they use. The first is to bypass an object, instrument adequately, and seal the object in the canal. Loose fragments may be removed with a broach wrapped in cotton. Another method is to prepare a trench around the item with a