Purpose: to compare the differences in the penetration depths of nickel-titanium (NiTi) and SS finger spreaders in prepared straight and curved canals..
N= 70 mandibular molar canals with root curvatures of 0 to 51 degrees
•The angle of curvature for each root canal was determined radiographically by the method described by Schneider. The teeth were instrumented with K-flex files and flared with Gates Glidden burs by a crown-down/balanced-force technique to a master apical file size of 35.
•the teeth were placed in a radiographic mount and postoperative radiographs were exposed in a buccolingual direction with comparable sizes of SS ( #20) and NiTi (fine-medium) spreaders inserted into each prepared canal.
•The distance from the apex of each root to the tip of the spreader was measured on the radiograph, with a micrometer
Most highlighted Results:
•NiTi spreaders penetrated to a significantly greater depth than SS spreaders. The mean values for distance from the apex was 1.15 mm for the NiTi spreader and 2.4 mm for the SS spreader.
•No statistically significant difference was found in straight canals.
NiTi spreaders can be used to compact GP in curved canals to a greater depth than SS spreaders.
•The radiographic method may not be as accurate as direct measurement. •The measurements were obtained without obturation materials in the canals.
•The apical force used during spreader insertion was not standardized.