مقايسه ميزان جابجايي كانال هاي خميده به دنبال استفاده از فايل هاي استنلس استيل و نيكل تيتانيوم INUITRO( )

Evaluation of curved canal dislocation after using nickel titanium (NT) and stainless steel (SS).fles (in vitro)

Background & Aim: Canal preparation is the hardest and most time consuming stage of the root canal therapy, particularly in curved narrow canals. The main error that occurs in these canals is overwidening. The aim of this study was to compare the quantity of curved canal dislocation after using two types of endodontic files made of nickel-titanium (NT) and stainless steel (SS). Method & Materials: In addition we used two kinds of movements in our study to evaluate their effects on quality of canal preparation.40 same acrylic blocks with a 40 degrees gradual curve were made and were divided into 4 groups of 10. 1) Nitiflex (NT) with Filing movement, 2) Nitiflex with Watch-winding movement, 3) Flexofile (SS) with Filing movement, 4) Flexofile with Watch-winding movement. Canal shapes were stored in the computer memory before doing any preparation. Then the canals were prepared in all groups with Passive Step-Back technique. Canal shapes were stored in the computer memory again. Primary and secondary pictures were superimposed with an especial computer program. The quantity of removed material from the inner and outer canal walls was evaluated in 1 sections from the apex to the 10 millimeters above it (beginning of the curve). At last the results were analyzed with Kruskal-Wallis variance analysis. Results: The quantity of material removed with SS files was significantly more than NT files (P0.05). Also the Nf files prepared the canal more suitable.