Ionic liquid as antibacterial agent for an experimental orthodontic adhesive.

OBJECTIVE: The aim of this study was to formulate and evaluate experimental orthodontic adhesives with different concentrations of 1-n-butyl-3-methylimidazoilium bis(trifluoromethanesulfonyl)imide (BMIM.NTf(2)). METHODS: The experimental orthodontic adhesives were formulated with methacrylate monomers, photoinitiators and silica colloidal. The ionic liquid BMIM.NTf(2) was synthesized and characterized. BMIM.NTf(2) was added at 5 (G(5%)), 10 (G(10%)) and 15 (G(15%)) wt.%. One group contained no BMIM.NTf(2) to function as control (G(Ctrl)). The adhesives were evaluated for polymerization kinetics, degree of conversion (DC), Knoop hardness and softening in solvent, ultimate tensile strength (UTS), shear bond strength (SBS), thermogravimetric analysis (TGA), antibacterial activity and cytotoxicity. RESULTS: BMI.NTf(2) showed the characteristic chemical peaks. The polymerization kinetics were different among the groups. G(10%) and G(15%) showed higher DC (p < 0.05). G(5%) and G(Ctrl) had no differences for softening in solvent (p > 0.05). There were no differences for UTS (p > 0.05) and SBS (p > 0.05). TGA showed one different peak for G(15%). All groups with BMIM.NTf(2) showed antibacterial activity compared to G(Ctrl) (p < 0.05) without cytotoxicity (p > 0.05). SIGNIFICANCE: To reduce biofilm formation around brackets and to prevent demineralization at susceptible sites, materials have been developed with antibacterial properties. In this study, a new experimental orthodontic adhesive was formulated with an imidazolium ionic liquid (BMIM.NTf(2)) as antibacterial agent. The incorporation of 5 wt.% of ionic liquid decreased biofilm formation without affecting the physico-chemical properties and cytotoxicity of an experimental orthodontic resin.