Introduction: Endodontic instruments upon rotation are subjected to both tensile and compressive stresses in curved canals. This stress is localized at the point of curvature. It has been demonstrated that the continuous cycle of tensile and compressive forces in the area of curvature of the canal to which (Nickel Titanium) NiTi rotary instruments are subjected produce a very destructive form of loading, causing cyclic fatigue and eventually fracture of the instrument.2 The aim of this study is to conduct a systematic review on the effect of cryogenic treatment on fracture resistance of nickel titanium rotary instruments.
Methods: Two Internet sources of evidence were used in the search of appropriate papers satisfying the study purpose: the National Library of Medicine (MEDLINE PubMed) and Google Scholar, Google and manual search using DPU college library resources. All cross reference lists of the selected studies were screened for additional papers that could meet the eligibility criteria of the study.
Results: Preliminary screening consisted total of 54 articles out of which 24 articles were selected. The papers were screened independently by two reviewers. At first the papers were screened by title and abstract. As a second step, full text papers were obtained when they fulfilled the criteria of the study aim. Any disagreement between the two reviewers was resolved after additional discussion. Finally 3 articles were included in this study.
Conclusions: Within the limitations of this study we can conclude that the cryogenic treatment increases the fracture resistance of nickel titanium rotary instruments.
Treatment;Fracture Resistance;Nickel-Titanium Rotary Instruments