## 4 Discussion  
According to the guidelines provided by ESE, the assessment of the technical quality of root canal treatment focus on the length of the filling material (between 0.5 to 2 mm from the radiographic apex) and the homogeneity of filling density, with the absence of empty spaces, that must be interpreted radiographically [22]. Considering these strict criteria, 87.5% of the filling's quality performed by an undergraduate student were considered \"adequate\", with 95% and 92.5% presenting the required length and density, respectively. These values are relevant because the quality of the root canal fillings is associated with the root canal treatment's prognosis. Moreover, studies report that a poorer obturation quality is associated with a lower success rate, i.e., more prone to persistent post-treatment disease [27,28]. However, epidemiological evaluations of the technical quality and result/outcome of treatments performed have recognized the need to improve the performance of students and general dentits in endodontics' clinical practice [14,29,30]. Studies stress that, before graduation, students should be exposed to various clinical cases adapted to their level of training, to prepare for a future independent, but responsible, clinical practice. This will allow the acquisition of the necessary skills to adequately perform simple procedures. It is  
Figure 4: Multiple comparisons between treatment time and quality per group, by preparation order. (**A**)—Total instrumentation time; (**B**)—active instrumentation time; (**C**)—obturation time. (“\(\circ\)”—outlier). Figure 3: Profile graph of total instrumentation, active instrumentation, and obturation times per group (10 canals) by preparation order. also essential that every agent know their limits and be aware of the need for continued learning throughout their lifetime [16; 31]. Thus, introducing new materials and techniques in undergraduate teaching, as well as monitoring the results obtained, is imperative for a better outcome for future professionals, to provide the best and safest clinical practice for patients [14; 29]. In this sense, the present investigation had the purpose of assessing novel strategies, such as the introduction of a mechanized instrumentation system within undergraduate teaching, through a pilot study, evaluating its performance in curved simulated canals. It was, thus, the specific purpose of the present investigation to evaluate ET's quality and time required for an inexperienced operator to perform root canal treatments using the reciprocating motion (WOG) and a matched gutta-percha cone associated to an epoxy-based sealer. The outcome of the 40 simulated canals, sequentially prepared, were compared. They were divided into four groups of 10, ordered from the first to the last (40 th) canal prepared. With the results obtained, a profile graph was presented. It enabled an estimate of the minimum number of treated canals needed to stabilize the performance outcome of undergraduate students with reciprocating instrumentation. This could be traced only based on ET time spent by the student, as there were no differences regarding filling quality. To increase the reliability of the results, three observers were considered, including two other final-year students of the integrated Master's in dental medicine and an Endodontics professor (observer 3). In this study, the simulated canals facilitated visualization, through photographs, evaluated by three previously calibrated observers. There was a high overall agreement between the observers, which was expected. This is because the evaluation was done through photographs of the transparent cubes, without the limitations of conventional periapical radiographs. Similar to other studies, the present investigation used artificial canals [11; 26; 32]. Although allowing a better standardization of shape, length, and degree of curvature, their properties are not identical to dentin, which may have influenced the results, and thus, be a limitation of the investigation.