Polyethylene vinylacetate and fluoride layered double hydroxides composites for dental applications

The increasingly widespread use of oral medical devices such as aligners and mouthguards is associated with an increased risk of oral diseases, and enamel demineralization with the formation of white spot lesions. In this paper, polymeric composites based on ethylene vinyl acetate (EVA) incorporating ZnAlGa layered double hydroxides, intercalated with fluoride and benzoate anions, were developed to provide fluoride release and antibiofilm activity. The presence of Zn2+ and Ga3+ cations was designed to impart antibiofilm properties, while fluoride ions contribute enamel remineralization effect. Composite films containing 2.5 and 5 wt% inorganic filler were prepared by solvent casting. X-ray diffraction and scanning electron microscopy revealed the formation of microcomposites with well-dispersed particles within the polymer matrix. Fluoride release studies demonstrated an initial ion release within 48 h, with fluoride still retained in the films after 20 days. The composites showed dose-dependent inhibition of biofilm formation by Candida albicans, without exerting cytotoxic effects on oral mucosal keratinocytes. Importantly, mechanical testing indicated that the incorporation of inorganic filler did not alter the mechanical properties of EVA. Overall, these results suggest that the composites are promising candidates for the fabrication of aligners and mouthguards.