## 3 Results  
In Figure 2A, the 3% DMAHDM, 5% DMAHDM, and 5% DMAHDM-20% NACP groups had experienced a significant reduction in the flexural strength following the water aging (\(p<0.05\)). Although values are acceptable according to ISO 4049 [37]. For the elastic modulus (Figure 2B), experimental control, 3% DMAHDM, 5% DMAHDM, and 3% DMAHDM-20% NACP were increased after aging by around 8% (\(p>0.05\); power of analysis = 100%). For the biofilm inhibition, the DMAHDM-NACP composites significantly reduced the CFU counts of the total microorganisms' growth in comparison to the control group by 2-3-log (\(p>0.001\); power of analysis = 100%). (Figure 3A). Overall, the log reduction was reduced after aging by around 0.5-1-log using the 5% DMAHDM, 3% DMAHDM-20% NACP, and 5% DMAHDM-20% NACP composites (Figure 3D). For the total _Streptococci_, all the antibacterial formulations resulted in significant inhibition of 1.5-3-log after aging (\(p<0.001\)) (Figure 3B). After normalizing the data, the bacterial log reduction demonstrated that the 3% DMAHDM-20% NACP group was the only composite with a significantly reduced antibacterial action by around 1-log (Figure 3E). For _mutans streptococci_, all the formulations significantly (\(p<0.05\)) reduced the CFUs after aging (\(p<0.001\)). However, (Figure 3F) showed a significant decline of 1-1.5-log of the antibacterial formulations against the _mutans streptococci_ CFU. When analyzing the metabolic activity results, all the antibacterial formulations demonstrated metabolic activity reduction following aging (\(p<0.05\)). However, the 5% DMAHDM and 5% DMAHDM-20% NACP groups showed slightly increased activity compared to the baseline samples. When the data were normalized (Figure 4B), the aged samples were found to reduce the metabolic activity by 61-86%, while the baseline samples reduced it by around 68-89%. No significant difference was found between aged and non-aged samples concerning each group after normalizing the data except for the 5% DMAHDM group (Figure 4B). For the lactic acid production, the 5% DMAHDM and 5% DMAHDM-20% NACP groups significantly (\(p<0.05\)) decreased the lactic acid production after aging compared to the control (Figure 4C). The lactic acid production was slightly increased after aging concerning each antibacterial formulation. The capability of lactic acid inhibition was reduced by around 15-35% (Figure 4D). The 3% DMAHDM is the only group that did not show a reduced inhibition after aging compared to the baseline counterpart (\(p>0.05\)). The live/dead images showed high quantification of viable microorganisms over the experimental control (Figure 5B). The incorporation of 3% and 5% DMAHDM into the composite formulation was associated with a mixture of viable and dead/compromised colonies (Figure 5C,D). Adding 20% of NACP to the DMAHDM was associated with the minor viable microorganisms (Figure 5E,F). Figure 2: **(A)** The flexural strength values (mean \(\pm\) SD; n = 6) of different composite formulations at baseline and after aging. **(B)** The elastic modulus values (mean \(\pm\) SD; n = 6) in different composite formulations after aging and at baseline. * Asterisks indicate significant differences compared to baseline values before aging. Figure 3: Colony-forming unit (CFU) counts of the (**A**) total microorganisms, (**B**) total streptococci, and (**C**) _mutans streptococci_ on the composite surface (mean \(\pm\) SD; n = 9). Different letters indicate significant differences between groups (\(p<0.05\)). The difference in the log reduction between the baseline and aged samples concerning the (**D**) total microorganisms, (**E**) total streptococci, and (**F**) _mutans streptococci_ is illustrated. * Asterisks indicate significant differences compared to baseline values before aging. (EC = experimental control; 3D = 3% DMAHDM; 5D = 5% DMAHDM; 3 DN = 3% DMAHDM-20% NACP; 5 DN = 5% DMAHDM-20% NACP). Table 1 shows the topography changes following the simulated wear.