## 1 Introduction  
With increased life expectancy, root canal treatment and novel endodontic therapy proposals have emerged with a great impact, enabling the retention of natural permanent teeth that otherwise would be lost. The aim of endodontic treatment (ET) is to remove pulp tissues, dental debris, and microorganisms, achieving the adequate conditions that will enable a proper filling and sealing of the root canal system. To reach this purpose, effective cleaning and shaping is essential. Over the years, mechanized instruments have been developed and commercialized to overcome the difficulties inherent to the conventional and rigid stain-steel (SS) manual instrumentation, simplify procedures, reduce the time required for root canal preparation, and offer a safer approach associated with less risk of errors and complications [1]. Amongst a myriad of new instruments and devices, the reciprocating movement is one of the most recently reported. It is a single-file system producing faster and centered shaping procedures, when compared to the traditional rotary instruments [2]. Not less important, for student's safety, is the single-use (reciprocating) file's concept, preventing cross-infection or reducing cyclic and torsional fatigue, as well as instrument's corrosion by irrigating solutions [3]. Thus, it is suggested as one of the most suitable systems for inexperienced operators, namely, undergraduate students [4]. Therehave also been reported contradictory findings, claiming that shaping procedures with ProTaper Next instruments, for instance, removed less resin from the curvature, showing a better centering ability than the reciprocating WaveOne Classic system [5]. The authors emphasized the different taper of the instruments (WaveOne 0.08, ProTaper Next 0.06) as the main factor for the different outcome. Nevertheless, improvements in the instrument designs to obtain greater flexibility are still emerging. WaveOne Gold (WOG; Dentsply Sirona) uses the same kinematics as its predecessor, WaveOne (classic) (WO; Dentsply Sirona, Ballaigues, Switzerland), but has some differences in design, size, and taper. The Wave One Gold instrument has a parallelogram cross-sectional design with two cutting edges incorporating four instruments: 21/06 (small), 25/07 (primary), 35/06 (medium), and 45/05 (large). A new reciprocating glide path instrument, the WaveOne Gold Glider, has also been introduced, with 0.15-mm tip diameter and variable 2%-6% taper. The innovative gold treatment increases the flexibility and resistance to cyclic fatigue and improves cutting efficiency [6; 7]. It also allows a more conservative preparation, while maintaining the original shape of the root canal [8]. It is reported to be less prone to dentin removal during instrumentation [9], even in canals with high curvatures [10]. In addition, it enabled a faster canal preparation compared to other nickel-titanium (Ni-Ti) instrumentation systems, such as ProTaper Next [11]. Studies evaluating non-surgical ET, performed by specialists, report success rates of over 90%, with differences between initial/primary root canal treatments compared to non-surgical retreatments [12]. Regarding undergraduate students, it has been reported that the quality of endodontic treatment is poor, with unsatisfactory success rates, particularly in multirooted teeth [13; 14]. The authors were unanimous in stressing the importance of introducing new teaching methodologies, techniques, and instruments into educational preclinical and clinical undergraduate curricula to improve general practitioners' confidence in root canal treatments. There is a growing trend of Ni-Ti rotary techniques taught in dental schools, with reports appearing nowadays of the clinical performance of Ni-Ti instruments operated by undergraduate students. [PERSON] et al. [15] observed that undergraduate dental students could achieve better canal preparations with Ni-Ti, although file separations may still be the main concern for beginners that avoid using Ni-Ti rotary systems.