Interfacial Adhesion of Mouthrinses to Orthodontic Metal Wires: Surface Film Viscoelasticity Effect

This study concerns the evaluation of adhesive and wettability energetic signatures of a model orthodontic wire exposed to commercial mouthrinses. The surface wetting properties were evaluated from the contact angle hysteresis (<i>CAH</i>) approach applied to dynamic contact angle data derived from the original drop on a vertical filament method. Young, advancing, receding <i>CA</i> apart from adhesive film pressure, surface energy, work of adhesion, etc. were chosen as interfacial interaction indicators, allowing for the optimal concentration and placement of the key component(s) accumulation to be predicted for effective antibacterial activity to eliminate plaque formation on the prosthetic materials. Surfactant compounds when adsorb at interfaces confer rheological properties to the surfaces, leading to surface relaxation, which depends on the timescale of the deformation. The surface dilatational complex modulus <i>E</i>, with compression elasticity <i>E_d</i> and viscosity <i>E_i</i> parts, determined in the stress-relaxation Langmuir trough measurements, exhibited the viscoelastic surface film behavior with the relaxation times (0.41-3.13 s), pointing to the vertically segregated film structure as distinct, stratified layers with the most insoluble compound on the system top (as indicated with the 2D polymer film scaling theory exponent y = 12.9-15.5). Kinetic rheology parameters could affect the wettability, adhesion, and spreading characteristics of mouthrinse liquids.