###### Abstract  
The aim of this study was to compare the behavior of two heat-treated file systems on resin blocks in unskilled hands. For this purpose, an in vitro, randomized, cross-sectional study was conducted to compare ProTaper Gold (PTG) with BlueShaper (BS) files. A total of 81 resin blocks were used and analyzed photographically to assess the amount of material removed during instrumentation. PTG removed more material on the outside of the curve in the coronal and apical third, while BS removed more material on the inner part of the curve in the middle third. The procedural errors observed in the total sample were apical transportation (33.8%), blockages (4.9%), ledges (3.7%), and canal perforation. PTG produced more apical transportation, and there were no statistically significant differences between the groups in the formation of ledges, canal perforations, or blockages. No file fractures were recorded during the study. Within the limitations of this study, we can affirm that neither file excessively deformed the artificial canals, and the PTG file produced more apical transportation. d 202  
undergraduate students to use rotary instrumentation with nickel-titanium (NiTi) instruments [8, 17; 18; 19] because they allow the performance of RCTs to be achieved in a fast and predictable way [3, 11; 16; 20; 21], presenting lower complication rates [10; 22] due to the fact that these rotary instruments cause fewer errors in the root canal preparation compared to manual files [23] because they are more flexible [24]. With NiTi instruments, it is possible to improve the student's experience in their preclinical training [10] because, by performing these treatments more quickly, the number of practice attempts is increased, and an increase in the repetition of a procedure has proven to be very useful in preparing students in the acquisition of acceptable preclinical skills that will translate into better preparation and the optimization of their future professional practices [4, 11; 22; 25; 26]. When it comes to selecting an ideal rotary instrument for inexperienced hands, there is a wide range available on the market today [24]. In the design of this type of files, there is great variability in terms of alloys, cross-sectional design, cutting edges, tapering, etc., in addition to the thermo-mechanical treatment of the NiTi alloy itself, which is carried out to optimize its microstructure and therefore its mechanical performance, giving it greater flexibility and resistance to fracture [23; 27; 28]. Since the release of the first conventional NiTi instruments, thermomechanical treatments have been developed that could induce changes in their behavior through stability in the martensitic phase, increasing their flexibility and resistance to cyclic fatigue under clinical conditions, thus creating a new generation of instruments and alloys [29]. Thus, up to the present date, NiTi alloy instruments with thermomechanical treatments have been launched on the market: M-Wire, R-Phase, CM-Wire, Blue, Gold, and Max Wire [23], and more recently, the Pink alloy in the year 2020. The effects of heat treatment depend on time, temperature (T), processing sequence, and the amount of previous cold working. These treatments aim to change the transitional T of the alloy (i.e., the T at which the crystalline arrangement of NiTi atoms changes from an austenitic, cubic phase to a martensitic, tetragonal molecular arrangement [30]. New generations of NiTi rotary systems include ProTaper Gold files (Dentsply Sirona, Ballaigues, Switzerland), a system made of a NiTi alloy called \"Gold,\" which, according to the manufacturer, confers greater flexibility and which presents a convex, triangular-shaped section, as well as BlueShaper files (Zarc4 Endo Gijon, Asturias, Spain). BlueShaper is a system made of a double NiTi alloy, called \"Pink wire\" and \"Blue wire\" which, according to the manufacturer, gives it resistance to torsion and cyclic fatigue. Like ProTaper Gold, it has a convex, triangular cross-section.