## 4 Discussion
In addition, all the specimens in the control group experienced adhesive failures (100%). However, the overall analysis revealed 96.6% cohesive failure in the aged composites among all adhesive groups, indicating that adhesive bonding is stronger than cohesive bonding of the aged composites in all test groups, which were treated using different adhesive systems. Traditional bond strength tests, such as shear and microtensile methods, have long served as the primary means of evaluating the effectiveness of dental adhesive systems. However, their ability to accurately simulate intraoral conditions remains questionable. Variations in test geometry, the load application angle, and specimen dimensions can lead to inconsistent results, failing to reflect the true performance of materials in clinical practice. Several studies have highlighted these limitations. For instance, [PERSON] et al. [51] emphasized that standardized laboratory bond strength tests only provide limited predictive power for clinical outcomes. Similarly, a study conducted by [PERSON] et al. [52] demonstrated that shear bond strength tests resulted in more uniform stress distributions and fewer pretest failures compared to microtensile tests, especially when analyzed via FEA. This method also proved essential in visualizing how stress concentrates at the adhesive interface, allowing for a more precise evaluation of bond performance. In the present study, both shear bond strength (SBS) testing and FEA were employed to assess the impact of silane-containing adhesive systems on the repair bond strength of resin composites. While SBS tests revealed significant improvements in bond strength when silane was incorporated, the FEA results added an essential layer of understanding by illustrating reduced stress concentrations at the interface, particularly for silanized surfaces. This aligns with the findings of [PERSON] et al. [53], who confirmed the critical role of silane in stabilizing the adhesive layer, improving stress transfer. Additionally, [PERSON] et al. and [PERSON] et al. [13; 14] emphasized that laboratory testing alone might overlook such subtle mechanical effects, and combining it with FEA provides a more clinically relevant perspective. In contrast, the results obtained in studies by [PERSON] et al. and [PERSON] et al. [54; 55] showed some inconsistencies in silane efficacy, likely due to differences in substrate conditioning protocols or material aging, which again highlights the value of mechanical modeling in standardizing evaluation. In addition to bond strength values, the displacement results obtained from FEA provided further insight into the mechanical stability of the adhesive interface. Lower displacement values, as observed in the silane-treated groups such as Silane + PQ1 and All-Bond Universal, indicate reduced interfacial deformation under applied stress. Clinically, this may translate into better load distribution and improved resistance to functional forces during mastication. Conversely, the higher displacement observed in the PQ1 group suggests increased flexibility or a weaker interface, which could potentially compromise the long-term stability of the repair. Therefore, adhesives that achieve both high bond strength and minimal displacement may offer superior clinical performance in composite repair applications. Finally, these findings support the notion that conventional bond strength tests should be supplemented with numerical analyses, such as FEA, to better approximate the clinical reality. FEA allows for not only essential verification of test-derived bond strength values but also enables the prediction of failure modes under various loading conditions. This dual approach \"combining empirical testing with simulation\" offers a more robust framework for evaluating adhesive systems, particularly when considering complex substrates or multi-material restorations. This study presents several limitations that should be acknowledged.