F^- Release From Innovative Flowable Composites and RMGIC Containing LDH

Objectives: To analyse the effect of a rechargeable Fluoride (F^-) battery based on Layered Double Hydroxides (LDH) on the uptake and release of F^- from flowable dental composites and RMGIC.
Methods: LDH, preloaded with F^-, was admixed in a hand mixed light cured RMGIC GC Fuji II LC (FII) and two light cured flowable composites: 3M Filtek Supreme XTE (FS) and Voco Grandio Flow (GF). The test group (n=6) contained 0.85% w/w of LDH whereas the control group (n=6) did not contain LDH. All samples were produced as discs measuring 1mm X 10mm. Discs were individually immersed in 10ml of water of water and stored at 37^oC. The water was collected and changed daily for 5 days. On the 5^th day the discs were individually immersed in 10ml of 0.05% NaF solution and vigorously shaken for 60s to simulate rinsing with mouthwash. Thereafter the discs were again stored at 37^oC immersed in 10ml deionised water. The water was then collected and changed daily for a further 5days. The periodically collected water and the NaF solution used for rinsing was analysed for F^- concentration using F^- electrode (Thermo Orion, USA) to measure F^- release, F^- uptake and F^- re-release.
Results: LDH significantly increased F^- release, uptake and re-release from FS and GF (p<0.05). However, LDH containing FII showed reduced F^- release, uptake and re-release.
Conclusions: The incorporation of LDH enhanced the release, uptake and re-release of F^- from the two light cured composites but does not, however, have a similar effect on the release, uptake and re-release of F^- from the RMGIC.