## 4 Discussion  
Incorporating antimicrobial agents into resins aims to reduce biofilm at the tooth-restorative material interface [1, 2, 7, 18]. BMI.NTf\({}_{\text{2}}\) was previously incorporated into an orthodontic resin and demonstrated an antibacterial effect against biofilms of \(S\). _mutans_ and planktonic \(S\). _mutans_[13]. However, the physicochemical properties were impaired by 10 wt.% of BMI.NTf\({}_{\text{2}}\)[13]. This ionic liquid was added to an experimental adhesive resin in the present study, and its physicochemical properties were analyzed. There was no statistical difference in the DC among G\({}_{\text{TRL}}\), G\({}_{\text{1\%}}\), and G\({}_{\text{2.5\%}}\). The incorporation of 5 wt.% of BMI.NTf\({}_{\text{2}}\) increased the DC compared to G\({}_{\text{CTRL}}\) and G\({}_{\text{1\%}}\) (\(p<0.05\)), while the softening in solvent was higher with 5 wt.% addition. Ionic liquids are exploited as solvents [10], and their properties are responsible for increasing the stability of the drug formulation and strengthening the association between drugs and surfactants or polymers. Furthermore, they facilitate drug transport to the target site of action and increase the solubility of moderately water-soluble drugs [10]. The chemical structure of BMI.NTf\({}_{\text{2}}\) gives it antimicrobial activity: the cationic structure is attracted by the negative charge at the bacterial wall and membrane compounds by electrostatic forces [9]. Moreover, its alkyl chain and anion, NTf\({}_{\text{2}}\), present hydrophobicity, assisting in disorganizing the bacterial wall and membranes [9]. The increase in the concentration of BMI.NTf\({}_{\text{2}}\) demonstrated a higher DC. Ionic liquids are characterized by molecular properties such as charge distribution, dipole moment, polarizability, hydrogen acceptance/donation, and electron pair acceptance/donation [10]. The carbon double bonds present in the monomers can interact with the presence of ionic liquids through hydrogen bonds or interaction of the electron pair of the double bond with the electronic cloud of ionic liquid [10]. This interaction can increase the conversion of carbon double bonds for groups with a higher concentration of BMI.NTf\({}_{\text{2}}\). In addition to the DC being altered, the polymerization kinetics can change depending on the compound added by modifying the mobility of the polymer chains [13, 17]. The polymerization kinetics of the dental adhesive resins incorporating the ionic liquid BMI.NTf\({}_{\text{2}}\) provided insightful data that helped elucidate the underlying mechanisms of the observed results. Notably, the polymerization reaction in the samples containing BMI.NTf\({}_{\text{2}}\) demonstrated a marked acceleration compared to the control group (G\({}_{\text{CTRL}}\)). The increased polymerization rate for the BMI.NTf\({}_{\text{2}}\) groups may be attributed to a reduction in the viscosity of the adhesive resin [13]. The handling properties of the material changed according to ionic liquid concentration. Despite not being tested in the present study, the adhesive with 5 wt.% of ionic liquid seemed to have a lower viscosity than the control group. It is possible that the increased DC% observed for this group was due to a greater mobility of the polymer chains during the curing process [13]. The addition of BMI.NTf\({}_{2}\) possibly interfered with the mobility of the chains and the density of crosslinks, leading to plasticizing effects [14, 19, 20]. Polymers with lower crosslink density are prone to soften more when in contact with alcoholic solutions [19]. Similar results were observed in a previous study with orthodontic adhesive resins with the addition of BMI.NTf\({}_{2}\)[13]. This effect was also investigated by thermogravimetric analysis (TGA), and the higher the ionic liquid concentration, the higher the formation of novel derivative (DTG) of the TGA curve.