Comparison of original and similar manufactured different nickel titanium instruments in terms of standardization and mechanical resistance

Since 1989, many developments have been observed in nickel- titanium endodontic instruments and today many systems with different design, manufacturing, usage, and metallurgical aspects are available. The aim of improvements is to improve the fracture resistance of instrument, besides the effectiveness of the instruments. Despite all, instrument fracture still causes an important problem. In recent years, the production of counterfeit or replica-like of well-known and widely used nickel-titanium systems is quite common. Due to the lack of sufficient scientific data on the quality and performance of these systems, their uses cause a risk for the treatment success and complications. In our study, ProTaper Next (Dentsply Sirona Ballaigeus, Switzerland) and Reciproc (VDW Munich, Germany) systems were compared with similar productions of these systems in terms of design and standardization by the using SEM and stereo microscope. In addition, the systems were evaluated in terms of metallurgical properties and mechanical fracture resistance (cyclic fatigue and torsional strength tests). As the systems are observed in terms of design and standardization, the files of similar manufactured have a more sharp-active tip design, and more blunt-rounded cutting blades. EDS analysis provided that Ni amount in original and counterfeit products is not similar. In the mechanical resistance tests, while the ProTaper Next showed similar values with the similar manufactured system, the Reciproc showed higher values. In the DSC analysis of the systems, it was seen that the phase transformation temperatures of the similar manufactured systems were different than the original systems. Key Words: nickel-titanium, similar manufactured systems, mechanical resistance tests, standardization, scanning electron microscopy