Novel rechargeable calcium fluoride dental nanocomposites

Composite restorations with calcium fluoride nanoparticles (nCaF₂) can remineralize tooth structure through F and Ca ion release. However, the persistence of ion release is limited. The objectives for this study were to achieve long-term remineralization by developing a rechargeable nCaF₂ nanocomposite and investigating the F and Ca recharge and re-release capabilities.

Three nCaF₂ nanocomposites were formulated: (1) BT-nCaF₂:Bisphenol A glycidyl dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA); (2) PE-nCaF₂:Pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA); (3) BTM-nCaF₂:BisGMA, TEGDMA, and Bis[2-(methacryloyloxy)ethyl] phosphate (Bis-MEP). All formulations contained 15% nCaF₂ and 55% glass particles. Initial flexural strength and elastic modulus, F and Ca ion release, recharge and re-release were tested and compared to three commercial fluoride-containing materials.

BT and BTM nCaF₂ composites were 3-4 times stronger and had elastic modulus 2 times that of resin-modified glass ionomer controls. PE-nCaF₂ had comparable strength to RMGIs. All nCaF₂ composites had significant F and Ca ion release and ion rechargeability. In F and Ca recharging cycles, PE-nCaF₂ had the highest ion recharging capability among nCaF₂ groups, followed by BT-nCaF₂ and BTM-nCaF₂ (p < 0.05). For all recharge cycles, ion release maintained similar levels, demonstrating long-term ion release was possible. Furthermore, after the final recharge cycle, nCaF₂ nanocomposites provided continuous ion release for 42 days without further recharge.

Novel nCaF₂ rechargeable nanocomposites exhibited significant F and Ca ion release over multiple recharge cycles, demonstrating continuous long-term ion release. These nanocomposites are promising restorations with lasting remineralization potential.