Aim: The aim of this paper was to characterize the active ingredients of ACP remineralizing pastes MI PasteTM and MI Paste PlusTM. Materials and Method: Two CPP-ACP containing products MI PasteTM and MI Paste PlusTM with addition of 900ppm sodium fluoride (NaF) supplied by GC America Inc. were evaluated. The free fluoride content of MIPaste PlusTM was quantified using a fluoride ion selective electrode (Orion 9609BN, 710A meter, South Burlington, VT, USA). 1.50 g of MI Paste PlusTM was dissolved thoroughly in 100 ml de-ionized water. Samples were prepared in duplicate. Ten grams of each product was weighed and mixed with 40ml of deionized water in a centrifuge tube. The solutions were vacuum filtered using a suction filtration setup, which consisted of a filter paper with pore size of 5-13 μm (Fisher Scientific, Loughborough), a Buchner funnel (250 ml, VWR, Leicestershire), a 500ml suction flask (Duran, Mainz) and a vacuum pump (KNF, Neuberger). The extracts were oven dried at 37°C for 24 hours prior to the further characterization by a combination usage of X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and 31P and 19F Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). Results and Conclusions: The characterization of the extracts from MI PasteTM and MI Paste PlusTM clearly demonstrated varying degrees of the conversion of the ACP to apatite. A more significant conversion was observed in the MI Paste PlusTM with soluble fluoride. The fluoride ions bound to calcium and phosphate ions to form chemically stable fluorapatite, which resulted in a deficiency of mineral ions for remineralization, subsequently reduced the remineralization rate. The usage of sodium monofluorophosphate as an alternative to sodium fluoride could, however prevent this undesired conversion
