Fluoride Release and Recharge Property of Hydroxyapatite-Ionomer Cement

To identify the optimum hydroxyapatite (HA) and glass-ionomer cement (GIC) combination that will yield the maximum amount of fluoride release.

Methods:

A chemical-curing GIC sealant (Fuji III™) was used as the control and base material. Finely ground hydroxyapatite (HA-f) was added from 8-32wt% into the GIC powder and mixed with polyacrylic acid at P/L 1.2. Samples (N=6/group) measuring 10 mm in diameter x 2 mm thickness were prepared and stored in 10 ml of distilled water and renewed every　24 hours. The measurement of fluoride elution was done every 24 hours for 14 days. On the 7th day, the samples were recharged in 900 ppm of sodium fluoride solution for 5 minutes then submerged in a container of fresh distilled water. The mean fluoride elution for each day was calculated and analysis was performed using an appropriate t-test and one-way ANOVA.

Results:

There was consistent increase in the fluoride released from HA-added samples compared to the control. For samples added with 8-16% HA-f, the increase was noted from day 1-14, while the increase was noted with 24% HA-f from day 4-14 and with 32% HA-f from day 7-14. The highest increase was noted with the addition of 24% HA-f with a total accumulated fluoride release 342.0 µg/cm² compared to 240.0µg/cm² of the control by the 14th day.

Conclusion:

To a certain level, the more is the amount of added HA, the higher is the increase in the fluoride released. HA-ionomer cement had 8-32% lesser fluoride-containing glass components compared to the control but was able to release increased amount of fluoride. HA-ionomer cement has the potential as a fluoride-releasing restorative and sealant material.

Acknowledgement:

This research is being supported by the Japan Science and Technology Agency (JST) and JSPS Grant-in-Aid for Scientific Research (A) # 20241020.