## 3 Results
### Failure Mode Distribution  
For the classification of failure types, a quantitative method was chosen over qualitative estimation. All fractured interfaces were examined and photographed under a stereomicroscope at 20\(\times\) magnification to inspect the bond failure type. The percentage of the resin composite area that remained bonded to the ceramic surface versus areas where cohesive failure occurred within the ceramic bulk were calculated for each specimen using image editing software (GIMP-GNU 2.10.18 Image Manipulation Program). Specimens that exhibited debonding in more than 75% of the total surface were classified as adhesive failures, while those showing cohesive failure in more than 75% of the composite bulk area (no cohesive failures were observed in the ceramic bulk) were classified as cohesive failures. Samples with areas of debonding representing between 25% and 75% of the total sample surface were classified as mixed failures.  
The frequency of the mode of failure is presented in Table 5, and representative images under the microscope are shown in Figure 2. Considering the significances of Pearson's chi-squared (\(\chi^{2}\)) test it can be assumed that there was a relationship between \"Treatment\" and \"Failure type\" (\(p<0.05\)). Mixed failures were the most common failure type across all groups. In total, 12 (24%) specimens exhibited adhesive failure, 12 (24%) had cohesive failure in the resin bulk, and 26 (52%) specimens demonstrated mixed failure types. Group B predominantly displayed mixed failure types, while the addition of Ivoclean to the bonding protocol, regardless of whether sandblasting was performed (groups C and D), increased the frequency of cohesive failures due to enhanced bond stability. Interestingly, in Group F, where bond strength was the highest, failure types were primarily mixed as well. This was likely related to the distribution of forces during testing.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Groups** & **A** & **B** & **C** & **D** & **E** & **F** \\ \hline A & - & - & - & - & - & - \\ \hline B & - & - & 0.607 & 0.321 & 0.787 & 0.091 \\ \hline C & - & 0.607 & - & 0.643 & 0.759 & 0.055 \\ \hline D & - & 0.321 & 0.643 & - & 0.415 & 0.026 \({}^{\star}\) \\ \hline E & - & 0.787 & 0.759 & 0.415 & - & 0.052 \\ \hline F & - & 0.091 & 0.055 & 0.026 \({}^{\star}\) & 0.052 & - \\ \hline \end{tabular}
\end{table}
Table 4: One-way ANOVA pairwise comparisons of \(p\)-values of the experimental groups in the study. Values with asterisk indicate statistically significant differences (\(p<0.05\)).  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Groups** & **Surface Treatment** & **Adhesive** & \
\begin{tabular}{c} **Cohesive in** \\ **Resin Bulk** \\ \end{tabular} &
\begin{tabular}{c} **Cohesive in** \\ **Ceramic Bulk** \\ \end{tabular} & **Mixed** \\ \hline A & None & - & - & - & - \\ \hline B & SB + MEP + AU & 2 & 0 & 0 & 8 \\ \hline C & SB + IC + MEP + AU & 3 & 4 & 0 & 3 \\ \hline D & IC + MEP + AU & 3 & 3 & 0 & 4 \\ \hline E & MEP + AU & 1 & 4 & 0 & 5 \\ \hline F & SB + MEP + IC + MP + AU & 3 & 1 & 0 & 6 \\ \hline \end{tabular}
\end{table}
Table 5: Distribution of failure mode after shear bond strength test. (a) Adhesive: failure between ceramic and resin cement; (b) Cohesive in resin bulk: failure in the resin cement; (c) Cohesive in ceramic bulk: failure in the ceramic bulk; and (d) Mixed: failure including both adhesive and cohesive failure in the restorative material and/or resin cement.