## 4 Discussion  
Bioactive composites are constantly being investigated to reduce the risk of treatment failure over time. One drawback of this process is the short-term effect of the materials on bacterial growth [13]. As a result, bioactive dental composites may demonstrate reduced antibacterial properties and weak mechanical performance, threatening their clinical longevity. Early failure of composite restorations may occur due to the breakdown of the resin matrix and its interface with the filler. The hydrolysis of the silane-resin bond could be another mechanism for degradation due to aging [38]. These different degradation patterns may leach the resin matrix and initiate cracks and flaws within the composite's structure, which could deteriorate the restoration's mechanical properties [39]. The degradation and leaching process can chemically and physically change the structure of the composite [18]. Antibacterial formulations with a high rate of degradation and structure changes due to aging are highly expected to lose their bioactivity and strength. As a result, the long-term evaluation of bioactive formulations' antibacterial and mechanical performance is essential before translating them into clinical models. This study has investigated the impact of water aging on the bioactive composite formulations containing DMAHDM and NACP. Our hypothesis was partially accepted since after one year of water aging; the bioactive formulations demonstrated great antibacterial \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Resin Composite Formulation** & **Ra (\(\mu\)m)** & **Rq (\(\mu\)m)** & **Rv (\(\mu\)m)** & **Rt (\(\mu\)m)** \\ \hline
**Commercial Control** & 0.292 \(\pm\) 0.098 \({}^{\text{a}}\) & 0.189 \(\pm\) 0.109 \({}^{\text{a}}\) & 0.590 \(\pm\) 0.178 \({}^{\text{a}}\) & 1.583 \(\pm\) 0.429 \({}^{\text{ab}}\) \\
**Experimental Control** & 0.104 \(\pm\) 0.067 \({}^{\text{a}}\) & 0.250 \(\pm\) 0.107 \({}^{\text{a}}\) & 0.221 \(\pm\) 0.092 \({}^{\text{a}}\) & 0.325 \(\pm\) 0.048 \({}^{\text{a}}\) \\
**3\% DMAHDM** & 0.223 \(\pm\) 0.145 \({}^{\text{a}}\) & 0.307 \(\pm\) 0.158 \({}^{\text{a}}\) & 0.439 \(\pm\) 0.363 \({}^{\text{a}}\) & 1.212 \(\pm\) 0.627 \({}^{\text{ab}}\) \\
**5\% DMAHDM** & 0.310 \(\pm\) 0.227 \({}^{\text{a}}\) & 0.304 \(\pm\) 0.164 \({}^{\text{a}}\) & 0.591 \(\pm\) 0.549 \({}^{\text{a}}\) & 1.674 \(\pm\) 1.032 \({}^{\text{ab}}\) \\
**3\% DMAHDM-20\% NACP** & 0.282 \(\pm\) 0.176 \({}^{\text{a}}\) & 0.323 \(\pm\) 0.180 \({}^{\text{a}}\) & 0.604 \(\pm\) 0.438 \({}^{\text{a}}\) & 1.250 \(\pm\) 1.036 \({}^{\text{ab}}\) \\
**5\% DMAHDM-20\% NACP** & 0.313 \(\pm\) 0.166 \({}^{\text{a}}\) & 0.388 \(\pm\) 0.249 \({}^{\text{a}}\) & 0.790 \(\pm\) 0.422 \({}^{\text{a}}\) & 2.120 \(\pm\) 1.537 \({}^{\text{b}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The difference in average surface roughness (\(\Delta\)Ra), maximum peak height (\(\Delta\)Rq), maximum valley depth (\(\Delta\)Rv), and the average distance between the highest peak and lowest valley (\(\Delta\)Rt) of the resin composite formulations subjected to cyclic fatigue (mean \(\pm\) SD). Values indicated by different letters are statistically different from each other (\(p<\) 0.05). Figure 6: Scanning electron microscopy showing the topography changes on the composites’ surfaces following the simulated wear at \(\times\)100, \(\times\)500, and \(\times\)1000 magnification. action but slightly reduced certain mechanical properties compared to the baseline samples. This present study provides the first outcomes of long-term aging of bioactive composites containing DMAHDM and NACP. The use of contact-killing monomer in the resin matrix was proposed in 1993 [40]. Since then, several QAMs have been used to impart bioactivity in resin-based materials. DMAHDM, as an antibacterial monomer, has a broad antimicrobial spectrum. Its antibacterial mechanism depends on contact inhibition where the positively charged quaternary amine N\({}^{+}\) sites contact the negatively charged bacterial cell membrane [41].