## 4 Discussion
\begin{table}
\begin{tabular}{c c c c} \hline  & **2 mm** & **5 mm** & **8 mm** \\ \hline TAC-OR & 0.101 \(\pm\) 0.002 ** & 0.128 \(\pm\) 0.002 * & 0.162 \(\pm\) 0.004 * \\ TAC-PU & 0.103 \(\pm\) 0.001 ** & 0.131 \(\pm\) 0.002 * & 0.167 \(\pm\) 0.004 * \\ CAC-OR & 0.125 \(\pm\) 0.001 ** & 0.142 \(\pm\) 0.004 * & 0.182 \(\pm\) 0.003 * \\ CAC-PU & 0.122 \(\pm\) 0.001 ** & 0.143 \(\pm\) 0.002 * & 0.184 \(\pm\) 0.004 * \\ \hline \end{tabular} TAC-OR: traditional access cavity—One Reci; TAC-PU: traditional access cavity—ProIaper Ultimate; CAC-OR: conservative access cavity—One-Reci; CAC-PU: conservative access cavity—ProIaper Ultimate. *Indicates a statistically significant difference (\(p<0.05\)). **Indicates a statistically significant difference (\(p<0.01\)).  
\end{table} 
Table 3: The mean transportation values of the groups in the mesiolingual canals are shown at a distance of 2 mm, 5 mm, and 8 mm from the apical area. prepared, this result agrees with [PERSON] et al. 's results obtained by investigating the effects of traditional and ultraconservative access cavities on the shaping of mandibular central teeth [31]. Additionally, [PERSON] et al. evaluated the shaping efficiency of two different rotating and reciprocating files in traditional and ultraconservative cavities of mandibular molars. Similarly, no effect of different cavity types and files on the surface area change was found in this study either [14]. As a result of root canal shaping with OR and PU, no effect of the Ni-Ti file system used was found on the surface area change regardless of endodontic access cavity type (\(p>0.05\)). The preparation was carried out by selecting files with similar apical diameters and similar tapers in both systems. Therefore, the morphological and geometrical changes in the root canals were similar. A statistically significant difference was found between the groups in terms of non-instrumented area (\(p<\)0.05). This difference arose independently of the Ni-Ti instrument system used. This result is in agreement with the results of the study obtained by [PERSON] et al. [14]. In a separate similar study, [PERSON] et al. emphasized that conservative access cavities remain more non-instrumented than traditional access cavities [32]. The reason for this result may be that the files cannot provide a completely straight-line entrance to the root canals in CAC groups and touch more cavity and canal walls until they reach the apex. The Ni-Ti instrument system used in the aforementioned studies, similar to this study, did not affect the non-instrumented area. Non-instrumented areas of the canal walls obtained by micro-CT analysis were observed, especially in the apical region and isthmus areas. However, these areas may contain pulp tissue, bacteria, and dentin residues. These data show that studies should continue to make irrigation and shaping protocols more effective [33]. In a minimally invasive treatment, the amount of non-instrumented area should be disinfected using complementary cleaning methods, not by increasing the taper of the Ni-Ti instrument used [34]. Thus, unnecessary dentin is not removed from the middle and coronal parts of the root canal, and the resistance of the endodontically treated teeth against root fractures is increased [35]. The percentage of unprepared areas is significantly reduced with the increase in the instrumentation size from 25 to 40, regardless of the system used. However, this situation may conflict with minimally invasive treatment principles, and by utilization of a modern system with a regressive taper, pericervical dentin can be preserved without compromising it [36]. One of the major points of mechanical damage as a result of excessive instrumentation in an already slim dentin wall under normal conditions is that it can lead to failure of root canal treatment [37]. [PERSON] et al. stated in their study that such damage may cause perforations in the middle section of the root. This section is known as the danger zone and is located in the distal area of the mesial roots of mandibular molars.