Mechanical Performance and Metallurgical Features of ProTaper Universal and 6 Replicalike Systems

Introduction: This study aimed to compare the ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland) system with 6 replicalike instruments regarding instrument design, mechanical performance, and alloy characteristics. Methods: New rotary instruments (size 20/.07v) of PTU and 6 replicalike systems (EdgeTaper [EdgeEndo, Johnson City, TN], U-File [Dentmark, Ludhiana, India], Go-Taper Universal [Access, Shenzhen, China], Super Files [Flydent, Shenzhen, China], Multitaper [Proclinic Expert, Besancon, France], and Pluri Taper [Bestdent, Shenzhen, China]) (n = 329) were selected and evaluated regarding their design, mechanical performance, and metallurgical characteristics. The results were compared using the nonparametric Mood median test and 1-way analysis of variance with the significance level set at 0.05. Results: Replicalike instruments were similar to PTU regarding design, maximum torque to fracture (P > .05), and ratio of nickel and titanium elements. Scanning electron microscopy revealed differences in the geometry of the tip and finishing surfaces. Time to fracture of Go-Taper Universal (50.0 seconds) was similar to PTU (44.0 seconds) (P > .05), but the U-File (63.5 seconds), Edge Taper (87.5 seconds), and Super Files (130 seconds) showed significantly higher values (P < .05). The highest maximum torque was observed in the Super Files instrument (P < .05), but no statistical difference was noted among the other instruments (P > .05). The angle of rotation before rupture of the Multitaper (574 degrees) and Pluri Taper (481 degrees) was higher than PTU (354 degrees) (P < .05). Differential scanning calorimetric analysis showed clear differences on the transformation temperatures among the tested instruments. The R-phase start and finish temperatures of PTU were 11.0 degrees C and -18.0 degrees C, respectively. Conclusions: Overall, replicalike instruments were similar to PTU regarding the torsional resistance, geometric design, and near equiatomic proportions of nickel and titanium elements. In 3 of the 4 mechanical tests, the EdgeTaper (torque, angle of rotation, and bending load) and Go-Taper Universal (time to fracture, torque, and angle of rotation) systems were similar to PTU.