## 3 Results  
Results obtained from micrographs scoring are presented in detail in Table 1. The mean scores of the smear layer and the intergroup and intragroup comparisons are presented in Table 2.  
Group A and Group D present significant differences (\(p<0.05\)) for smear layer removal score, as reported in Figure 2, which describes the smear layer reduction after the tested irrigation methods in each of the root canal thirds. The apical third of Group A displayed the highest percentage of Score #5, while Group D showed the lowest score for the apical third (Score #2).  
These findings are displayed in Figure 3, which presents the morphology of different root canal wall surfaces. The representative scanning electron micrographs of Group A showed several opened dental tubules with the presence of a small amount of smear layer in the coronal third (Score #2). In contrast, the middle third displayed a greater number of closed dental tubules due to the growing presence of the smear layer, which instead completely covered the wall surface of the apical third (Score #5). The irrigation system  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Tested** & **Root Canal** & **Score \#1** & **Score \#2** & **Score \#3** & **Score \#4** & **Score \#5** \\ \hline \multirow{3}{*}{Group A} & Coronal & 0 & 15 (50\%) & 14 (46.7\%) & 1 (3.3\%) & 0 \\  & Middle & 0 & 0 & 19 (63.3\%) & 6 (20\%) & 5 (16.7\%) \\  & Apical & 0 & 0 & 8 (26.7\%) & 9 (30\%) & 13 (43.3\%) \\ \hline \multirow{3}{*}{Group B} & Coronal & 17 (56.7\%) & 13 (43.3\%) & 0 & 0 & 0 \\  & Middle & 0 & 19 (63.3\%) & 6 (20\%) & 5 (16.7\%) & 0 \\  & Apical & 0 & 0 & 13 (43.3\%) & 10 (33.3\%) & 7 (23.4\%) \\ \hline \multirow{3}{*}{Group C} & Coronal & 17 (56.7\%) & 8 (26.7\%) & 5 (16.6\%) & 0 & 0 \\  & Middle & 0 & 15 (50\%) & 10 (40\%) & 5 (10\%) & 0 \\  & Apical & 0 & 0 & 21 (70\%) & 5 (16.7\%) & 4 (13.3\%) \\ \hline \multirow{3}{*}{Group D} & Coronal & 23 (76.7\%) & 7 (23.3\%) & 0 & 0 & 0 \\  & Middle & 16 (53.3\%) & 14 (46.7\%) & 0 & 0 & 0 \\ \cline{1-1}  & Apical & 0 & 15 (50\%) & 11 (36.7\%) & 4 (13.3\%) & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Numerical value and percentage scores (%) of smear layer in agreement with [PERSON] et al. criteria per group.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Group A** & **Group B** & **Group C** & **Group D** \\ \hline Coronal & 2.53 \(\pm\) 0.57 a.1 & 1.43 \(\pm\) 0.5 b.1 & 1.6 \(\pm\) 0.77 b.1 & 1.23 \(\pm\) 0.43 b.1 \\ \hline Middle & 3.53 \(\pm\) 0.78 a.2 & 2.53 \(\pm\) 0.78 b.2 & 2.67 \(\pm\) 0.76 b.2 & 1.47 \(\pm\) 0.51 c.1 \\ \hline Apical & 4.17 \(\pm\) 0.83 a.3 & 3.8 \(\pm\) 0.81 ab.3 & 3.43 \(\pm\) 0.73 b.3 & 2.63 \(\pm\) 0.72 c.2 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mean values of smear layer scores (mean \(\pm\) standard deviation) in different groups (A, B, C and D) divided by the three regions of root canal (Coronal, Middle and Apical).  
In addition, for the apical third, both groups presented a uniform smear layer hiding the root canal surface with scarce empty dental tubules (Score #3). Finally, optimal results were obtained by Group D, which highlights the lack of smear layer in both the coronal and middle third and a Score #2 for the apical third.