The effect of different glass ionomer cements and surface coating applications on fluoride release and microhardness values

BACKGROUND: The glass-ionomer cements have many advantages such as the ability to form chemical bonding at the tooth-restoration interface, release and recharge of fluoride, low cytotoxicity and high biocompatibility. But their low mechanical properties and susceptibility to moisture contamination during hardening limit their usage the regions exposed to high stress. The surface coatings used to protect the physical and mechanical properties of the material reduce fluoride release. Therefore, this study aims to evaluate the effects of different glass-ionomer cements and surface coatings on fluoride-release and microhardness. METHODS: Three glass-ionomer cements; Ketac Molar Easymix (conventional), EQUIA Forte Fil (high-viscosity hybrid), and ChemFil Rock (high-viscosity zinc) were tested. Each cement formed 21 specimens, subdivided into control, petroleum jelly, and coat groups. Samples were submerged in deionized water, with fluoride release measured using an ion-selective electrode on days 1, 3, 7, 14, 21, 28, and 56. Microhardness was assessed using a universal testing device at baseline and after 130 days. RESULTS: Microhardness was assessed using a universal testing device at baseline and after 130 days. EQUIA Forte Fil showed the highest fluoride-release, while ChemFil Rock had the lowest (p ≤ 0.05). Surface treatments reduced fluoride-release for all materials, with no difference between petroleum jelly and coat groups. The highest microhardness was in EQUIA Forte Fil/control (baseline), and the lowest was in EQUIA Forte Fil/coat (p ≤ 0.05). Both EQUIA Forte Fil/control and ChemFil Rock/control showed decreased microhardness over 130 days (p ≤ 0.05). CONCLUSIONS: The results demonstrate that the coating of glass-ionomer surfaces reduce fluoride release via preserving surface integrity but it may potentially limit remineralization and anticariogenic benefits. The surface coating reduces the deformation in the structure of the material and microhardness change. These effects should be consider on treatment planning.