Functional MgAl LDH@SiO₂ Composites: Controlled Fluoride Delivery in Dentistry

Bio-silica particles derived from rice husks were coated with MgAl layered double hydroxides (LDHs) and thermally converted into layered double oxides (LDOs) to evaluate fluoride capture and release capability. The deposition of an MgAl LDH layer on the silica particle makes the LDH more accessible for interaction. Fluoride loading was tested in aqueous and ethanol-water media, with mixed solvents consistently enhancing uptake. Release studies in demineralized water showed relatively rapid desorption (~1500 min), whereas embedding particles in an acrylic matrix reduced the release rate by nearly two orders of magnitude, enabling sustained release levels suitable for dental applications. Ethanol promoted both ion exchange and memory effect mechanisms, providing tunable control over fluoride incorporation and release. These functional composites demonstrate potential for controlled delivery in dental restorative materials, highlighting their potential as adaptive fillers that can enhance the mechanical properties while also serving a functional base for low fluoride release.