Application of a hyaluronic acid-based lotions containing hydroxyapatite nano-particles approach for treatment of initial dental caries

This study evaluated the remineralization potential of a ceramic–polyelectrolyte system, based on a novel combination of hydroxyapatite nanoparticles (HAp NPs) and a hyaluronic acid (HY) matrix, for dental enamel, a tissue that remains challenging to repair in clinical dentistry. Nano-Hydroxyapatite (nanoHAp) powder was synthesized and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), and zeta potential analysis to confirm their crystalline structure, functional groups, morphology, particle size distribution, and colloidal stability. HY-based suspensions (remineralizing lotions) containing 5, 10, and 12 wt% of the synthesized nanoHAp particles were formulated via a combined electrostatic and electrosteric stabilization strategy using sodium hexametaphosphate (SHMP) as an ionic deflocculant. These suspensions were characterized by FTIR, FE-SEM, MTT cytocompatibility assay, and contact angle measurements to assess their chemical structure, morphology, biocompatibility and wettability. Therefore, the HY-based system was confirmed to possess a submicron structure and to be biocompatible, as well as to exhibit superior wettability compared with the individual components. Suspensions were evaluated for in vitro bovine enamel remineralization via micro-computed tomography (Micro-CT). All three HY-based formulations significantly exceeded a none-polyelectrolyte polymer-based suspension, while no significant differences were observed among the HY groups (p > 0.05). These findings indicate that the interaction between the nanoHAp and the HY as a polyelectrolyte matrix may play a dominant role in enhancing mineral deposition, underscoring the potential of this composite system for future enamel remineralization and biomimetic preventive applications.