The greatest amount of fluoride recharge is seen with:

The ability of a restorative material to be recharged and serve as a fluoride reservoir depends on the type and permeability of the material, the frequency of fluoride exposure, and the concentration of the fluoridating agent.  Glass ionomers and compomers are significantly better for recharging than resin-based composite materials, but this depends on the composition of the materials. Hybrid ionomers are often reported to have the highest capacity for recharging. It has also been reported that as the specimens age, their efficiencies of fluoride recharging decrease. Water soluble methacrylate-based monomers have been used to replace part of liquid component of conventional GIC resulting in a group of materials called resin-modified glass ionomer cements, also known as hybrid ionomer cement. Ref: Phillip’s Science of Dental Materials ed 12 pg 334