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Root canal centering ability of rotary cutting nickel titanium instruments: A meta-analysis

Aim: To systematically review articles on canal centering ability of endodontic rotary cutting Nickel-Titanium (Ni-Ti) instruments and subject results to meta-analysis. Materials and Methods: A comprehensive search was initiated on canal centering ability of different rotary cutting Ni-Ti files such as Protaper, Hero Shaper, K3, Mtwo, Race, Wave One by selecting articles published in peer reviewed journals during 1991-2013 using “Pub Med” database. Inclusion and exclusion criteria were established. A data was created by tabulating: Author name, publication year, sample size, number of experimental groups, methods to evaluate canal centering ability, instrument cross section, taper, tip design, rake angle, mean and standard deviation. The data generated was subjected to meta-analysis. Results: Maximum studies were found to be conducted on mesiobuccal canal of mandibular 1st molar with curvature ranging from 15-60°. The difference in canal centering ability of different rotary cutting Ni-Ti instruments was not statistically significant. Conclusion: All endodontic rotary cutting Ni-Ti instruments are capable of producing centered preparations. Protaper depicted the best centering ability. Computed tomography is an effective method of evaluating canal centering ability.