Fluoride Recharge of a Nano-Ionomer Restorative Material

Objective: To compare the in-vitro recharge capability of a novel resin-modified glass ionomer (RMGI) restorative material versus other conventional glass ionomers (GI).  Methods: Materials used were Ketac^TM Nano nano-ionomer (KN, 3M ESPE), Ketac^TM Molar (KM, 3M ESPE), and Fuji IX (F IX, GC).  Two sets of three cured discs (20 x 1 mm) of each product were prepared and stored in 37C deionized water.  Fluoride release was measured after 1, 7, 14, 28, 90 days using fluoride selective electrode and TISAB buffer solution.  At day 90, the second set of specimen were recharged by applying Oral-B Neutra-Foam, sodium fluoride foaming solution, for one minute and subsequently rinsed with deionized water for one minute and stored in 37C de-ionized water.  Fluoride release from recharged and control discs was measured after 1, 2, 3, 4, 7 days per above procedure.  Results: The mean values including their standard deviations are summarized in the following table:

Material	Chemistry	7 Day Cumulative F Release after 3 months (control), micro g F/g sample	7 Day Cumulative F Release after recharge at 3 months, micro g F/g sample
KN	RMGI	112 ± 21	210 ± 8
KM	GI	42 ± 3	100 ± 9
F IX	GI	85 ± 27	147 ± 45

Conclusion: ANOVA analysis was performed at p < 0.05 per Tukey's pairwise comparison test.  KN nano-ionomer, an RMGI, demonstrated significantly greater F-release after short exposure to external F source.  This behavior is similar to that previously reported for GI materials.