In-Depth metallurgical, design, and mechanical analysis of Reciproc Blue and four replica-like endodontic systems

Abstract Objectives This work aimed to evaluate the metallurgical, geometrical, and mechanical properties of 5 reciprocating endodontic files with similar cross-sectional geometry. Materials and Methods Reciproc Blue, ProDesign R, V File, V + File, and Univy One files were used. The evaluation of diameters was performed through high-quality photographs and Image J software. Cross-sectional scanning electron microscopy was performed in order to measure the 3 mm from the tip cross-sectional area and other aspects related to the active blade and tip. Differential scanning calorimetry tests were employed to assess the transformation temperatures and X-ray diffraction was used to identify the atomic structures. Standardized bending torsion tests were performed to evaluate the mechanical responses of the files. Results Significant differences were observed in the cross-sectional areas of the instruments. R-phase was predominated in most instruments, except for the Univy One system, which exhibited a combination of martensite and R-phase. The ProDesign R system demonstrated superior flexibility, while the Reciprocal Blue and V File systems exhibited greater resistance to torsion. Conclusions The cross-sectional area emerged as a pivotal factor influencing the mechanical characteristics of the studied files. However, the Univy One system presented high flexibility and large angular deflection despite having the highest cross-sectional area value, which suggests that the metallurgical aspects of this instrument play a major role in its mechanical behavior. Clinical relevance: Mechanical properties of endodontic files, such as flexibility, are very important to prevent failures during clinical practice and keep the original shape of the root canal.