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Received Nov 26, 2017; Revised Mar 13, 2018; Accepted Apr 16, 2018
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1. Introduction
The main objective of endodontic treatment is to eliminate or minimize microorganisms in the root canal system while maintaining the original shape and path of the root canal [1]. However, no instrument/technique can predictably eliminate all the microorganisms from the root canal system. The cleaning efficacy of endodontic instruments significantly decreases at the apical third of root canals [2]. Many root canals have curvatures, and endodontic instruments tend to return to their original straight position during instrumentation of curved canals [3, 4]. Dentinal wall thickness in root canals has a direct relationship with root resistance to lateral forces [5, 6].
In the recent years, several nickel titanium (NiTi) instruments capable of faster and more efficient root canal preparation were introduced in the market. These systems have differences in some features such as cleaning efficacy, stress applied to dentinal walls, and ability to prepare oval-shaped root canals [7].
One Shape file (MicroMega, France) operates with continuous rotational movement compared with the other single-file systems. One Shape instruments have higher cutting efficacy in the root, which is probably attributed to electropolishing, flexibility, and variable cross section along its blade [8]. Antibreakage control in this file increases its fracture strength. This system has a sterile file with a tip size of ISO 25, 0.06 taper, variable pitch and a noncutting (safety) tip for cleaning and shaping of root canals [5].
Reciproc file (VDW, Munich, Germany) is made of M-Wire, which increases its strength and flexibility [9]. This file has an S-shaped cross section and a noncutting (safety) tip operating with reciprocal motion. Reciprocal movement was introduced in 1985 and is composed of two rotations, namely, 150° counterclockwise and 30° clockwise motions. This file is available in three sizes and tapers: R25 (25/0.08), R40 (40/0.06), and R50 (50/0.05) [10, 11].
M-One (Park, China) is a single-file system with a tip size of ISO 25, 0.06 taper, and full rotational motion. The alloys used in its composition are CM-Wire and Neo NiTi, and it has a...