Shellac-based encapsulation model incorporating calcium fluoride for oral care applications

Fluoride-releasing systems are widely incorporated into dental products to prevent caries; however, fluoride ions readily interact with calcium compounds in oral formulations, resulting in deactivation and reduced effectiveness. To overcome this limitation, a simple extrusion method was designed to fabricate shellac-based biopolymer beads capable of encapsulating fluoride. The resulting beads had an average diameter of 2.54 ± 0.22 mm, with theoretical analysis supporting particle size dependence on extrusion tube diameter. Structural and stability characterization was conducted using optical and electron microscopy, elemental analysis, vibrational spectroscopy, and thermal profiling, confirming in situ calcium fluoride formation and effective pore sealing. Key formulation parameters-including shellac concentration, dissolution time, bead formation time, and hardening time-were optimized to improve bead morphology and fluoride retention. An in situ blocking strategy, involving controlled precipitation of calcium fluoride within the bead matrix during formulation, was implemented to minimize fluoride diffusion and enhance long-term stability. This approach achieved 70% active fluoride retention over 90 days. The proposed encapsulation model holds promise for applications in toothpaste and other dental care products.