A comparative evaluation of ion release characteristics of three different dental varnishes containing fluoride either with CPP-ACP or bioactive glass

Objective. To compare ion release characteristics of three different dental varnishes either containing CPP-ACP and fluoride (CPP-ACPF, MI Varnish GC, Japan), bioactive glass and fluoride (BGAF, Dentsply Sirona USA) or fluoride alone (NUPRO White, Dentsply Sirona USA) using fluoride-Ion Selective Electrode (F-ISE), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), F-19 and P-31 Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). Methods. A thin layer (0.0674 +/- 0.0005 g) of each varnish (20 x 25 mm in area) was spread on a roughened glass slide (n = 7). They were separately immersed in 10 ml Tris buffer (0.06 M, pH= 7.30), and changed after 1, 2, 4, 6, 24 and 48 h. Fluoride-ion concentration at each time using the F-ISE, whilst calcium and phosphate release were investigated using ICP-OES. XRD, FTIR. MAS-NMR analyses were also performed before and after immersion. Results. The cumulative F-ion release was significantly higher in CPP-ACPF (1.113 mmol/g) > BGAF(0.638)> F(0.112) (p <0.001). The cumulative calcium and phosphorus were higher in the CPP-ACPF (0.137 mmol/g, 0.119) than BGAF (0.067, 0.015) (p < 0.001) respectively. The XRD and F-19 MAS-NMR confirmed the presence of NaF peaks in all cases before immersion. There were less prominent signal and appearance of fluorapatite crystals after immersion. F-19 MAS-NMR revealed CaF2 formation after immersion in both CPP-ACPF and BGAF. P-31 MAS-NMR showed phosphate signals in both CPP-ACPF and BGAF before immersion. FTIR failed to show any signs of apatite formation. Significance. Both CPP-ACP and bioactive glass enhanced ion release without compromising the bioavailability of fluoride. The CPP-ACPF varnish had the most promising ion release. Crown Copyright (C) 2019 Published by Elsevier Inc. on behalf of The Academy of Dental Materials. All rights reserved.