Fluoride release and mechanical properties after 1-year water storage of recent restorative glass ionomer cements
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The objective of this study was to evaluate the relationships between fluoride release and mechanical properties after 1-year water storage of five recent restorative glass ionomer cements (GICs).
Materials and methods
Five GICs, FujiIX GP EXTRA (FEX), FujiIX GP (FIX), GlasIonomer FX-II (GFX), Ketac Molar Easymix (KME), and Riva Self Cure (RSC), were examined. Cumulative fluoride release, compressive strength, and surface hardness were measured up to 1-year storage (n = 5), and analyzed with one-way or two-way ANOVA and Tukey HSD test (α = 0.05). Elemental compositions before and after 1-year storage were also examined (n = 3).
The amounts of fluoride release were significantly different among the products. The highest amount of fluoride release occurred during the first day. Then, the amount of fluoride release rapidly decreased and still continued until 1-year storage. Compressive strengths indicated that two main factors were significant (GFX < FEX = RSC < FIX < KME; 1 day < 1 week = 1 month = 3 months = 6 months = 1 year), but surface hardness showed a slightly different tendency (GFX = RSC < FEX = FIX = KME; 1 year < 1 day < 1 week = 1 month = 3 months = 6 months). Significant correlation was found between decrease of silicon and decrease rate of the surface hardness.
Fluoride releases were detected up to 1-year storage, but the mechanical properties slightly decreased due to decrease of Si after 1-year storage. Elution of Si instead of fluoride release was considered more critical to deteriorate the mechanical properties of GICs.
Fluoride released for 1-year water storage will contribute to secondary caries prevention. The amount of fluoride release did not affect these mechanical properties. These results indicate the usefulness of these GICs.
KeywordsGlass ionomer cement Long-term stability Fluoride release Compressive strength Surface hardness Elemental analysis
The authors would like to thank Mr. Katsuhito Kato, researcher of GC Corp., for helping the measurement of fluoride release.
Conflict of interest
The authors declare that they have no conflict of interest.
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