To determine whether the first binding file at the working length is the apical diameter in curved root canal both before and after flaring: an in vitro study

Aim: To compare the effectiveness of different file system to determine the apical diameter of canal, before and after coronal flaring in teeth with curved apical roots. Material and methods: 30 extracted premolar teeth with apically curved canals were divided into 2 groups (n=15). In group 1 hand k files were used and in group 2 Ni-Ti hand files were used. After access opening and obtaining patency with no. 6 k file, progressively increasing number of file sizes were introduced in the canal upto the working length passively until binding sensation is felt in the canal with the file. The last file to passively reach the working length was fixed and was observed under stereomicroscope and the digital image was recorded. Then, cervical flaring was done in the canals and the files were reinserted in the canals and again observed under stereomicroscope. The digital images were analysed using AutoCad software. Results: There was no statistically significant difference between the mean diameter of files in group 1 (hand k files) and in group 2 (Ni-Ti hand files). Significant difference was found in the file diameter before flaring and after flaring in group 1 (k file) and in group 2 (Ni-Ti file). Conclusion: There is no difference between Ni-Ti hand files and k files in determining working width in apically curved canals.