## 4 Discussion
The studies also processed a control group and comparative classes that were used in the review. As a result, the frequency of microcracks could be determined using a SEM and a stereomicroscope, which examined cross-sections at 3 mm, 6 mm, and 9 mm from the apex. In this systematic analysis, 1529 teeth samples were studied, with mandibular preemolars and central incisors being the most commonly used teeth. Three research [33; 39; 42] recorded teeth with root curvature, while others reported teeth with a straight root. Thecurvature specifics were not defined by [PERSON] et al [41]. Conventional NiTi file systems were the most commonly used, followed by M-wire file systems. All experiments that used traditional NiTi files as an experimental group used the ProTaper Universal method. WaveOne method was used in 7 studies for M-wire, with ProTaper Next and Reciproc following it. R-TFA phase's system was the most widely used. When the occurrence of dental microcracks at various cross-sections was examined using SEM after using traditional NiTi file systems, a greater number of defects were found after using the ProTaper Universal method [32; 34; 36; 37; 38; 41; 43; 44]. WaveOne was associated with the highest number of dental defects among M-wire systems [33; 34; 36; 42]. Four M-wire studies [32; 38; 40; 42] that used ProTaper Next have registered a rise in the number of dental cracks scanned. There were less dental microcracks after using R-phase and SAF (hollow-file system). Moreover, it should be noted that R-phase and SAF instruments were the least often included in the studies included in this systematic analysis. [PERSON] et al., in 2014, [PERSON] et al., in 2017, and [PERSON] and [PERSON], in 2016, did not disclose any data at 6 and 9 mm cross-sections, so their conclusions might be inadequate. [PERSON] et al., in 2015, used all three mechanisms and found the lowest number of dental cracks as compared to the other findings in the study. The highest number of dental cracks was observed at 3 mm from the root apex, although as the distance from the apex increases, the number of microcracks decreases, with the least recorded at the 9 mm cross-section. See Table 5 for more information. All of the experiments had a control group for reference and a well-described protocol that was reported and evaluated using the [PERSON] quality evaluation of in vitro studies' criterion [31]. The papers were evaluated based on their congruence between the research methodology and the research topic or purpose, the process used to gather data, data representation and analysis, and interpretation of findings. Only papers that met these conditions were included (Table 6). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**No. ** & **Title** & **File System** & **Files Used** & \multicolumn{2}{c}{**No. of Specimen**} & \multicolumn{4}{c}{**Number of Denital Cracks at Different Cross-Sections**} \\ \hline  & & & & & **3 mm** & 6 mm & 9 mm & **Total** \\ \hline  & Conventional & ProTaper & & & & & & \\  & In Vitro Comparative Evaluation of & In Vitro Comparative Evaluation of & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file \\
1. & Detinal Microcracks’ Formation during & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file \\  & Root Canal Preparation by Different & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file & In Vitro-file \\  & Nickel-Titanium File Systems [32].