## 4 Discussion
This result was attributed to forming regions with different crosslink densities, with areas more linear than others, when the ionic liquid was incorporated in greater quantities [13]. The immersion of dental adhesive resins in solvent is a critical test to assess their durability and resistance to the oral environment, particularly to the effects of moisture. In the study under consideration, all experimental groups exhibited a reduction in hardness upon solvent immersion. Notably, the group with 5 wt.% of BMI.NTf\({}_{2}\) (G\({}_{5\%}\)) demonstrated a more significant decrease in hardness compared to the control group (GCTRLL). This finding contrasts with previous research conducted on an orthodontic resin formulation, which showed different behavior under similar conditions [13]. The divergent results between the two studies [13] can largely be attributed to the differences in the base resin compositions used in each. The orthodontic resin did not contain hydroxyethyl methacrylate (HEMA), a commonly used monomer in dental adhesives that is known for its hydrophilic properties. Instead, the orthodontic resin included triethylene glycol dimethacrylate (TEGDMA), which is less hydrophilic than HEMA. This reduced hydrophilicity likely contributed to the orthodontic resin's enhanced resistance to softening when exposed to solvents [13]. Additionally, the orthodontic resin incorporated silanized colloidal silica, a filler known to improve the physicochemical properties of polymers [5, 14]. The presence of this filler helps to increase the resin's mechanical strength and stability, making it less susceptible to softening and degradation upon solvent immersion. This enhancement is particularly important in orthodontic applications where the material must withstand prolonged exposure to a moist and mechanically challenging environment [21]. In contrast, the current study involving BMI.NTT\({}_{2}\) in dental adhesives explored concentrations of 1% and 2.5% (G\({}_{1\%}\) and G\({}_{2.5\%}\)), which did not significantly influence the solvent's softening behavior. This suggests that the crosslinking density within these groups, including the control (GCTRLL), is likely similar. The addition of BMI.NTT\({}_{2}\) at these concentrations does not alter the resin's network structure significantly enough to affect its solvent resistance [22]. The comparison of these two distinct resin formulations highlights the importance of base resin composition and the selection of appropriate additives and fillers in the achieving desired material properties [23]. The difference in behavior underscores the need for tailored resin formulations depending on the specific requirements of the dental application, be it orthodontic or adhesive applications. For future formulations, understanding the interaction between the resin matrix, fillers, and any ionic liquids like BMI.NTT\({}_{2}\) will be crucial in developing materials that combine optimal mechanical properties and resist environmental challenges. Furthermore, an assessment of the cohesive strength of the polymers was conducted in addition to the evaluation of softening in solvent. In congruence with a prior study [13], no significant statistical disparities were observed among the various groups. Despite the adverse impact of incorporating 5 wt.% BMI.NTT\({}_{2}\) on the adhesive's softening behavior, this concentration exhibited no discernible alteration in the adhesive's ultimate tensile strength (UTS). Nonetheless, given the outcomes of the softening in solvent tests and the understanding of the potential effects of high concentrations of ionic liquids on polymer structure formation, the utilization of 2.5 wt.% BMI.NTf\({}_{2}\) emerged as the most suitable choice for the experimental adhesive resin. As a limitation of this study, the mechanical property was not tested directly on dentin. Therefore, the next steps encompass a set of antimicrobial analyses and the microtensile bond strength to dentin.