NICKEL-TITANIUM VERSUS STAINLESS-STEEL FINGER SPREADERS IN CURVED CANALS

Placement of endodontic spreaders to within 1 to 2 mm of the root cana l working length has been advocated for optimum gutta-percha obturatio n. Due to their stiffness, stainless-steel (SS) spreaders will often f ail to achieve this position in curved canals. Newly marketed nickel-t itanium (NiTi) spreaders may offer an advantage in this regard due to the increased flexibility of these instruments. Seventy mesial and dis tal mandibular molar canals were instrumented to a #35 master apical f ile size. Measurements of the canal curvature were made from preoperat ive radiographs. Canal curvature angles ranged from 0 to 51 degrees. T he teeth were placed in a radiographic mount to ensure a constant foca l length, and postoperative radiographs were exposed with comparably s ized SS and NiTi spreaders inserted into each prepared canal. Measurem ents of spreader tip to apex distance were made with a micrometer to t he nearest 0.02 mm on the radiographs. Using a t test for paired sampl es, it was shown that NiTi spreaders penetrated to a significantly gre ater depth than SS spreaders in curved canals (p < 0.001).