Glass ionomer materials as a rechargeable fluoride-release system.

It is well established that glass ionomers (GI) release fluoride (F). The degree of F released depends on the physical and chemical properties of the product. In the present study the fluoride release and the capacity of the GI to be recharged with fluoride was tested for five different brands: XR Ionomer (Kerr), Vitrebond (3M), GC Fuji Lining (G.C. Dental Industries Corp.), Baseline VLC (Dentsply) and Zinomer (Dent. Mat.). Fifteen test specimens were prepared for each brand. The specimens were immersed in deionized water. The F released was measured once a day for 11 days. Refluoridation of the test specimens was done with solutions of 0.02%, 0.04% and 0.2% NaF for 5 minutes on days 11, 16, 21 and 26. The F released from recharged specimens was measured daily until day 32. There was a positive correlation between the amount of F in the GI and the ability to release F. The five materials became 'recharged' with F following repeated F exposure in solution, the 0.2% solution being the most effective. XR ionomer released significantly more fluoride than any other material and showed the greatest ability to be recharged. Zinomer released significantly less fluoride than any other material and showed the least ability to be recharged. The present results indicate that GI serves as a F reservoir and can act as a prolonged slow-release system for at least 32 days.