## 4 Discussion  
This study was initially based on the hypothesis that there would be no significant difference in the \(\upmu\)TBS of SE adhesives when modified with different concentrations (0.15 wt%, 0.25 wt%, and 0.5 wt%) of ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\) compared to an unmodified SE adhesive. Additionally, it was anticipated that there would be no significant difference in the antibacterial efficacy or FTIR spectroscopy of ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\) NP-modified SE adhesive compared to unmodified SE adhesive. However, the results of this study revealed that all the groups in which the adhesive was modified using ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\) nanoparticles showed improved performance in terms of \(\upmu\)TBS and antimicrobial effectiveness against _S. mutans_. Nevertheless, there was a rejection of the hypothesis since the DC of the adhesive without nanoparticles was found to be higher compared to the adhesive loaded with ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\) nanoparticles. Numerous research studies have been conducted to explore the impact of integrating nanofillers into polymers. The primary objective behind the use of various engineered nanoparticles is to enhance the antibacterial effectiveness and bond strength of adhesives employed in restorative dentistry [28; 29]. The primary mechanism underlying the antibacterial activity of NPs is attributed to their interaction with the bacterial cell wall, facilitating  
Figure 4: The FTIR spectra comprise two sets: cured 0.5% ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\) and uncured 0.5% ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\). The spectral analysis was focused on the specific region between 1608 cm\({}^{-1}\) and 1636 cm\({}^{-1}\) for both the cured and uncured samples. The ratios of (C=C&C–C) absorbance intensities (percentage of unreacted double bonds) before and after polymerization were identified. their subsequent penetration of the cell membrane due to their tiny size [30]. In the present study, outcomes show that ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\) NPs, when used in different concentrations, display effectiveness against \(S\). _mutans_. This can be explained on behalf of previous studies which state that silver-phosphate glass particles possess bactericidal properties against various pathogens, such as Staphylococcus epidermidis, Enterococcus faecalis, and \(S\). _mutans_[31; 32; 33]. Reports have highlighted that the release of silver ions from nanoparticle surfaces plays a significant role in their detrimental effects. The liberated silver ions can penetrate bacterial cells, where they disrupt various enzymatic processes within the cellular environment. This interference ultimately culminates in the demise of the bacterial cells [34; 35]. However, the combination of ZrO\({}_{2}\) NPs with Ag\({}_{3}\)PO\({}_{4}\) works in synergy to improve the antibacterial potential of Ag\({}_{3}\)PO\({}_{4}\) by forming reactive oxygen species (ROSs) that lead to the destruction of bacterial cells. The increased levels of ROS kill bacteria by the process of lipid peroxidation. This is in agreement with the findings of a study conducted by [PERSON] and coworkers [36]. Nonetheless, this is the first study to assess the influence of ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\) nanoparticles on the survival of S. mutans, and further investigation is still required to gain a comprehensive understanding of the results and their implications. Regarding uTBS, it was determined that all ZrO\({}_{2}\)/Ag\({}_{3}\)PO\({}_{4}\)-modified experimental SE adhesives showed significantly higher bond strength values than the control. The findings of the current investigation align with prior research, indicating that the incorporation of nanofillers resulted in a notable enhancement in the adhesive strength of dentin [37; 38]. The nano-scale size of the two inorganic fillers employed in the present investigation could be considered a crucial aspect of this discovery.