## 3 Results  
A descriptive analysis of the microhardness and flexural strength data before and after thermal aging was performed for each resin (Tables 3 and 4). The median value of microhardness is 7.3 KHN for Deflex Classic SR samples after thermal aging and 14.6 KHN for Probase Hot samples before thermal aging. Regarding the effects of thermal aging, Deflex Classic SR and Deflex Supra SF showed lower values for microhardness after thermal aging (\(p\) = 0.001 and \(p\) < 0.001 respectively). However, no differences in microhardness before and after thermal aging were observed for the ProBase Hot samples (\(p\) = 0.599) (Table 3). There were no statistically significant differences in microhardness (\(p\) > 0.05) between the three resins, either before or after aging (Table 3). The median flexural strength values ranged from 52.5 MPa for Deflex Supra SF samples that were thermally aged to 80.1 MPa for Probase Hot samples prior to thermal aging. For all resins, no differences were found between the flexural strength values before and after thermal aging (\(p\) > 0.05) (Table 4). It was found that the ProBase Hot specimens had statistically significantly higher flexural strength values than the flexible resins (\(p\) < 0.001) and that there were no statistically significant differences between the flexible resins (\(p\) = 0.056) (Table 4). Following the chemical disinfection protocol, the median microhardness value ranged from 7.0 KHN for Deflex Classic SR samples subjected to the Corega Oxygen Bio-Active disinfection protocol to 14.6 KHN for ProBase Hot samples subjected to the Corega Whitening disinfection protocol (Figure 1). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multicolumn{2}{c}{**Flexural Strength (MPa) before**} & \multicolumn{2}{c}{**Flexural Strength (MPa) after**} \\ \cline{2-5}  & \multicolumn{2}{c}{**Thermal Aging**} & \multicolumn{2}{c}{**Thermal Aging**} \\ \cline{2-5}  & **Mean (\(\pm\)SD)** & **Median (IQR)** & **Mean (\(\pm\)SD)** & **Median (IQR)** \\ \hline ProBase Hot & 83.2 (\(\pm\)12.31) & 80.1 (23.22) & 71.0 (\(\pm\)18.39) & 66.9 (14.49) \\ Deflex Classic SR & 63.0 (\(\pm\)3.53) & 62.7 (5.35) & 69.4 (\(\pm\)3.82) & 61.2 (3.70) \\ Deflex Supra SF & 54.8 (\(\pm\)4.14) & 54.5 (8.13) & 52.6 (\(\pm\)2.70) & 52.5 (2.04) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Values for mean, standard deviation, median and interquartile range of flexural strength (MPa) of the tested materials before and after thermal aging. SD—standard deviation; IQR— interquartile range. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multicolumn{2}{c}{**Microhardness (KHN) before**} & \multicolumn{2}{c}{**Microhardness (MPa) after**} \\ \cline{2-5}  & \multicolumn{2}{c}{**Thermal Aging**} & \multicolumn{2}{c}{**Thermal Aging**} \\ \cline{2-5}  & **Mean (\(\pm\)SD)** & **Median (IQR)** & **Mean (\(\pm\)SD)** & **Median (IQR)** \\ \hline ProBase Hot & 14.6 (\(\pm\)3.13) & 14.6 (3.3) & 14.5 (\(\pm\)3.24) & 14.5 (3.3) \\ Deflex Classic SR & 7.8 (\(\pm\)1.60) & 7.5 (1.5) & 7.5 (\(\pm\)1.37) & 7.3 (1.4) \\ Deflex Supra SF & 8.6 (\(\pm\)2.10) & 8.6 (2.7) & 8.0 (\(\pm\)1.79) & 7.9 (2.3) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Values of mean, standard deviation, median and interquartile range of microhardness (KHN) of the tested materials before and after thermal aging. SD—standard deviation; IQR— interquartile range. Regarding the effect of chemical disinfection, the ProBase Hot samples subjected to the Corega Whitening protocol showed higher microhardness values than the other subgroups (vs. Corega Oxygen Bio-Active \(p\) = 0.023; vs. 2.5% sodium hypochlorite \(p\) = 0.04; vs. water \(p\) < 0.001). For Deflex Classic SR, the samples treated with Corega Oxygen Bio-Active showed lower microhardness values than the other subgroups (vs. Corega Whitening \(p\) < 0.001; vs. 2.5% sodium hypochlorite \(p\) = 0.04; vs. water \(p\) < 0.001).