## 3 Results  
The effect of irradiation on the tensile bond strength varied among the materials used, but a reduction was observed in all experimental groups.  
The results, respectively, mean tensile bond strength and standard deviation of each group, are presented in Table 3 and Figure 4. Figure 5 illustrates the spread of the resulting data.  
\begin{table}
\begin{tabular}{c c c c c} \hline \multicolumn{1}{c}{**Adhesive**} & **Batch Number** & **pH** & **Main Components * \\ \hline \multirow{4}{*}{F} & & & & BIS-GMA 1  & \multirow{4}{*}{LOT 1527116} & \multirow{4}{*}{2.3} & BIS-GMA 2  \\  & & & & Acidic adhesive monomer \\  & & & & Urethanedimetheacrylate \\  & & & & Catalyst \\ \hline \multirow{4}{*}{A} & & & & HEMA 2  \\  & & & & & Catalyst \\ \hline \multirow{4}{*}{X} & & & & HEMA 2  \\  & & & & & Catalyst \\ \hline \end{tabular}
\end{table}
Table 2: List of materials used.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Futurabond® U** & **AdheSE® Universal** & **Xeno® Select** \\ \hline
0 Gy & 23.87 & 35.10 & 24.17 \\  & \(\pm\)7.49 & \(\pm\)8.41 & \(\pm\)8.36 \\ \hline
5 Gy & 17.95 & 26.86 & 15.78 \\  & \(\pm\)5.95 & \(\pm\)7.41 & \(\pm\)3.89 \\ \hline
60 Gy & 19.21 & 26.30 & 11.42 \\  & \(\pm\)7.34 & \(\pm\)10.07 & \(\pm\)3.86 \\ \hline Decrease in mean microtensile & & & \\ bond strength after irradiation & \(-\)19.5\% & \(-\)25.1\% & \(-\)52.8\% \\  & \(\pm\)60 Gy compared to 0 Gy & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Testing results: mean microtensile bond strength in MPa (megapascal) and standard deviation.  
Figure 4: Mean microtensile bond strength and standard deviation of the experimental groups.  
Figure 5: Boxplot of the microtensile bond strengths (**a**) of the material Futurabond® U; (**b**) of the material AdheSE® Universal; and (**c**) of the material Xeno® Select. X = mean values in MPa.  
Considering the results for the material Futurabond(r) U, the value of the mean tensile bond strength without irradiation was 23.87 MPa (\(\pm\)7.49 MPa). Low dose irradiation (5 Gy) led to a decrease in the tensile bond strength of Futurabond(r) U to 17.95 MPa (\(\pm\)5.95 MPa). After irradiation with 60 Gy, the tensile bond strength of Futurabond(r) U did not decrease further (19.21 MPa \(\pm\) 7.34 MPa).  
Likewise, for AdheSE(r) Universal, the tensile bond strength of this material without irradiation was higher overall, with 35.10 MPa (\(\pm\)8.41 MPa). After irradiation with a low dose (5 Gy), there was a decrease in the tensile bond strength of AdheSE(r) Universal to 26.86 MPa (\(\pm\)7.41 MPa), but the dose increase to 60 Gy had no further effect; the tensile bond strength remained at 26.30 MPa (\(\pm\)10.07 MPa).  
Regarding material Xeno(r) Select, a gradual decrease in the tensile bond strength according to the increase in the irradiation dose was observed. The reduction from 24.17 MPa (\(\pm\)8.36 MPa) at 0 Gy via 15.78 MPa (\(\pm\)3.89 MPa) after 5 Gy to 11.42 MPa (\(\pm\)3.86 MPa) after 60 Gy irradiation dose, which occurred in self-etch-mode, represented the largest loss of tensile bond strength overall.  
The two-Way ANOVA revealed that the influence of irradiation and the used adhesive system on the microensile bond strength of the used dentin adhesive systems proved to be significantly different (\(p<0.01\)).  
In all experimental groups, a decrease in tensile bond strength between non-irradiated and irradiated groups was registered, at least after irradiation with 60 Gy. The percentage decrease within one material after a radiation dose of 60 Gy versus no radiation is listed in Table 3. Nevertheless, pairwise comparisons of the different groups revealed that the effect of irradiation on tensile bond strength was not significant for Futurabond(r) U and AdheSE(r) Universal ([PERSON]'s test, \(p>0.05\)). Only in the test series of the material Xeno(r) Select were the values of tensile bond strength in self-etch-mode after irradiation with 60 Gy significantly reduced compared to no irradiation (\(p<0.05\), [PERSON]'s test).