An Evaluation of Ion release From Fluoride Containing Dental Varnishes

Objectives: The objective of this in vitro study was to compare the cumulative fluoride, calcium and phosphorus ion release from three different dental varnishes containing fluoride either with CPP-ACP or Bioglass or fluoride only.
Methods: Three different fluoride formulations of dental varnishes were selected for this analysis. These were MI Varnish (GC, CPP-ACP+5%NaF), NUPRO NovaMin (DENTSPLY, NovaMin+5%NaF), and NUPRO (DENTSPLY, 5%NaF). Plastic microscope slides with rough surfaces were pre-weighed before coating an even layer of each dental varnish (0.0674±0.0005 gm) on an area of 20×25 mm separately. Seven samples were prepared for each group, and these were separately immersed in 10 ml tris buffer and kept in a shaking incubator at 37 °C. The samples were then removed from the solution and placed in vials containing 10 ml tris buffer after 1, 2, 4, 6, 24 and 48 hours. Fluoride was measured at each time using an Ion Selective Electrode F-ISE (Orion 9609BNWP, Thermo Fisher Scientific, MA, USA), whilst calcium, and phosphate ions release were determined at each time point using Optical Emission Spectroscopy (Vista-PRO, Varian Ltd, Oxford, UK).
Results: The cumulative fluoride release was significantly higher in dental varnish containing CPP-ACP and fluoride in comparison to either fluoride with Bioglass, or fluoride only varnish (p<0.001) at all time points. The cumulative calcium and inorganic phosphate ion release from fluoride varnish with CPP-ACP were also significantly higher when compared to fluoride varnish with Bioglass at all time points (p<0.001).
Conclusions: Fluoride containing dental varnish with either CPP-ACP or Bioglass improved fluoride ion release in a laboratory setting. Ion release characteristics of MI varnish was the most promising since this varnish had high fluoride, calcium, and phosphate ion release. The addition of calcium with phosphate ions and also Bioglass do not compromise the availability of fluoride ions in dental varnishes.