## 3 Results  
The distribution was normal and homogeneous for the adhesion strength data. The total mean value is 17.99 MPa (95% CI: 16.82-19.17 MPa) with a standard deviation of \(\pm\)6.72 MPa.  
The normality of the distribution of the variables was accepted, and the two-way ANOVA test showed the absence of a statistically significant difference, with \(p>0.05\) (\(p\)-value = 0.716), between the total means of the pretreatment groups with and without CHX; these were very similar to each other, as shown in Table 3 and in Figure 2. The effect size R\({}^{2}\) = 0.001 also showed no indication of a possible relationship that would justify the use of CH  
There were statistically significant differences \(p\) < 0.05 (\(p\)-value = 0.028), with a moderate effect size R\({}^{2}\) = 0.073, between the different types of adhesives. As a result, the mean BS value is higher in the Adper Prompt L-pop groups, 20.27 \(\pm\) 5.89 MPa, as shown in Table 4, although the [PERSON]'s post hoc paired t-test determines that this difference is not significant, \(p\) > 0.05 (\(p\)-value = 0.921).  
As for the failure type, the results did not demonstrate statistical significance, with \(p\) > 0.05. However, a moderate effect size (R\({}^{2}\) = 0.068) indicated differences in failure types by group. More adhesive failures were observed in the PL (43.8%) and PL-C (37.5%) groups. Cohesive failures were more abundant in the S-C (56.3%) and Sa (62.5%) groups. Mixed failures were more evenly distributed in all groups, as shown in Table 5.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**Bond Strength (MPa)**} \\ \hline \multicolumn{5}{c}{**Type of Adhesive**} \\ \hline \multicolumn{5}{c}{**Mean (SD)**} \\ \hline Scotchbond Universal & Scotchbond Universal & \multirow{2}{*}{Adper Prompt L-Pop} & \multirow{2}{*}{Adper Scotchbond 1 XT} \\ self-etch & total-etch & & \\ \hline
16.15 (8.53) & 16.34 (4.90) & 20.27 (5.89) & 19.22 (6.34) & 17.99 (6.72) \\ \hline \multicolumn{5}{c}{SD: standard deviation.} \\ \end{tabular}
\end{table}
Table 4: BS descriptive analysis depending on the type of adhesive.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Type of Adhesive**} & \multirow{2}{*}{**Pretreatment**} & \multirow{2}{*}{**Group**} & \multicolumn{3}{c}{**Type of Failure**} \\ \cline{3-5}  & & & \multicolumn{2}{c}{**\% (\(\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{ \mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{    }}}}}}}}}}}}}}\) \\ \cline{3-5}  & & & **Adhesive** & **Cohesive** & **Mixed** \\ \hline Scotchbond & without CHX & S & 18.8\% (3) & 43.8\% (7) & 37.5\% (6) \\ Universal self-etch & with CHX & S-C & 12.5\% (2) & 56.3\% (9) & 31.3\% (5) \\ \hline Scotchbond Universal total-etch & without CHX & Sa & 6.3\% (1) & 62.5\% (10) & 31.3\% (5) \\ \hline \multirow{2}{*}{Adper Prompt L-pop} & with CHX & Sa-C & 31.3\% (5) & 31.3\% (5) & 37.5\% (6) \\ \hline \multirow{2}{*}{Adper Prompt L-pop} & without CHX & PL & 31.3\% (5) & 37.5\% (6) & 31.3\% (5) \\ \cline{2-5}  & with CHX & PL-C & 25\% (4) & 31.3\% (5) & 43.8\% (7) \\ \hline Adper Scotchbond & without CHX & XTa & 43.8\% (7) & 18.8\% (3) & 37.5\% (6) \\ \cline{2-5}
1 XT & with CHX & XTa-C & 37.5\% (6) & 12.5\% (2) & 50\% (8) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Type of failure descriptive analysis by adhesive type and pretreatment.  
Figure 2: Comparative vision of BS (measured in MPa) by adhesive type and pretreatment. The error bars indicate the total mean standard deviation (SD) of the groups without CHX, and the groups with CHX, respectively.