Fluoride Release and Mechanical Properties of New Glass Ionomers

Newly introduced restorative glass ionomers are proclaimed to have superior properties.

Objectives: To assess the fluoride release and mechanical properties of 4 modern restorative glass ionomers (GIC).
Methods: Four restorative glass ionomers were studied:  A. ChemFil Rock (Dentsply); B. Fuji IX (GC); C. Riva (SDI); and D. Ketac Nano (3M ESPE). Ten discs from each material measuring 15mm (diameter) x 2.4mm were made in special molds. Fluoride release was measured in deionized water using a fluoride-specific ion electrode (Thermo Scientific). Cylindrical specimens (N=10) for testing compressive strength (CS) measured 6mm diam. X 6mm high; Specimens for diametral tensile strength (DTS) measured 6mm diam. X 3mm high (N=10).  All specimens were tested in a universal testing machine (INSTRON 5566A).
Results: Data were analyzed using ANOVA followed by Tukey's test. The fluoride release diagram for the 4 materials is shown below:

Mean CS and DTS values (MPa) are shown in the table below:

Significant differences in fluoride release were found among the materials (P=0.001). Differences became far smaller after Day 6, but still significant. CS data showed significant differences among the materials except between Fuji IX and Ketac Nano. The DTS results exhibited similar trends with ChemFil Rock and Ketac Nano exhibiting the highest values with no significant difference between them. We found a weak  inverse correlation between fluoride release and CS (r= -0.33); and fluoride release and DTS (r=-0.52).                             Conclusions: The restorative glass ionomers tested exhibited significant differences in fluoride release, with Fuji IX releasing more fluoride ion. ChemFil Rock exhibited the highest mechanical properties but the lowest fluoride release.