## 3 Results
The Kruskal-Wallis test revealed also statistically significant differences between the RCS volume of the RCSs randomly assigned to the Negative control group at the middle root third (\(0.96\pm 0.76\) mm\({}^{3}\)), compared to the EV study group (\(3.08\pm 1.26\) mm\({}^{3}\)) (\(p=0.023\)), EA study group (\(3.98\pm 1.57\) mm\({}^{3}\)) (\(p=0.014\)), and Positive control group (\(2.95\pm 1.31\) mm\({}^{3}\)) (\(p=0.019\)) (Table 2, Figure 4B). In addition, the Kruskal-Wallis test revealed statistically significant differences between the RCS volume of the RCSs randomly assigned to the Negative control group at the apical root third (\(0.04\pm 0.49\) mm\({}^{3}\)), compared to the EV study group (\(0.10\pm 0.88\) mm\({}^{3}\)) (\(p=0.023\)) and EA study group (\(0.08\pm 0.92\) mm\({}^{3}\)) (\(p=0.032\)). However, there were no statistically significant differences between the RCS volume of the EV and EA study groups (\(p=1.000\)) (Table 2, Figure 4C). The mean, median, and SD values of the relationship between the residual endodontic smear layer volume and the RCS volume at coronal, middle, and apical third of the RCS and the isthmus (%) are displayed in Table 3 and Figure 5A-C. \begin{table}
\begin{tabular}{c c c c c c} \hline  & & **EV** & **EA** & **Positive Control** & **Negative Control** \\ \hline \multirow{4}{*}{Coronal third} & \(n\) & 10 & 10 & 10 & 10 \\  & Mean & 5.74 & 6.25 & 5.90 & 1.73 \\  & Median & 5.04 & 6.42 & 5.28 & 1.82 \\  & SD & 2.24 & 1.60 & 2.62 & 1.17 \\  & Minimum & 2.03 & 3.87 & 3.25 & 0.37 \\  & Maximum & 9.04 & 8.55 & 9.02 & 9.04 \\ \hline \multirow{4}{*}{Middle third} & \(n\) & 10 & 10 & 10 & 10 \\  & Mean & 3.23 & 4.10 & 3.01 & 1.06 \\  & Median & 3.08 & 3.98 & 2.95 & 0.96 \\  & SD & 1.26 & 1.57 & 1.31 & 0.76 \\  & Minimum & 1.17 & 1.99 & 1.58 & 0.31 \\  & Maximum & 5.15 & 6.91 & 4.76 & 2.87 \\ \hline \multirow{4}{*}{Apical third} & \(n\) & 10 & 10 & 10 & 10 \\  & Mean & 2.1 & 1.94 & 1.78 & 0.60 \\  & Median & 0.10 & 0.08 & 0.13 & 0.04 \\  & SD & 0.88 & 0.92 & 1.26 & 0.49 \\  & Minimum & 0.78 & 1.07 & 0.50 & 0.14 \\  & Maximum & 3.52 & 4.02 & 3.97 & 4.02 \\ \hline \end{tabular}
\end{table} 
Table 2: Descriptive analysis of the residual endodontic smear layer present in the coronal, middle, and apical third of the RCS and the isthmus (mm\({}^{3}\)) of the study groups. Figure 4: Box plot of the root canal system volume in the coronal (**A**), middle (**B**), and apical third (**C**) of the RCS and the isthmus (mm\({}^{3}\)) of the study groups. The ANOVA test revealed statistically significant differences between the relationship between the residual endodontic smear layer volume and the RCS volume of the root canal systems randomly assigned to the Negative control group at the coronal root third (\(10.31\pm 9.22\%\)), compared to the EV study group (\(3.72\pm 3.35\%\)) (\(p=0.029\)) (Table 3, Figure 5A). However, there were no statistically significant differences between the study groups regarding the relationship between the residual endodontic smear layer volume and the RCS volume at middle root third (\(p=0.105\)) (Table 3, Figure 5B), or the apical root third (\(p=0.780\)) (Table 3, Figure 5C). Briefly, the coronal and middle root thirds of the RCSs randomly assigned to the EA study group showed higher residual endodontic smear layer volume than the EV RCSs randomly assigned to the EA study group; however, the volumes of the RCSs randomly assigned to the EV study group. By contrast, the apical root third of the RCSs randomly assigned to the EV study group showed higher residual endodontic smear layer volume than the EA RCSs randomly assigned to the EA study group; however, the volume of the RCSs randomly assigned to the EV study group were also higher than the RCSs randomly assigned to the EA study group. Hence, the relationship between the residual endodontic smear layer volume and the RCS volume showed a higher ratio relative to the EA study group at coronal and middle root thirds,