THE EFFECT OF FILING VERSUS REAMING ON THE SHAPE OF THE PREPARED ROOT CANAL,

The most common cause of endodontic failure is incomplete obliteration of the root canal, especially in the apical 5 mm. Success therefore depends on an ideal preparation that is, one that is smooth, tapering, and round in cross section to permit close conformation of the master cone used in canal obliteration. There is some question as to whether the various instrumentation techniques used within the dental profession all achieve the desired result. To answer this question, preparations were made in the root canals of thirty-three extracted mandibular central and lateral incisors then cross sections were measured mesiodistally and buccolingually to determine whether 1 different techniques of using files and reamers produced differences in intracanal preparations, and 2 files produced the same type of preparation when used with a reaming action as when used with a filing action. The ratio of buccolingual to mesiodistal dimensions was computed because excessive enlargement of the canal, when it occurred, was in the buccolingual dimension. The ratio for reamers was 1.0, for files used with a reaming action, 1.04, and for files used with a filing action, 1.26. Based on these results, a standard instrumentation technique is recommended. Author