Bioactivity of toothpaste containing bioactive glass in remineralizing media: effect of fluoride release from the enzymatic cleavage of monofluorophosphate

Objectives. The aim was to introduce a new methodology to characterize toothpaste containing bioactive glass and to evaluate the effect of release of fluoride ions, by cleaving monofluorophosphate (MFP), on the mineral forming ability of Sensodyne Repair & Protect (SRP). which contains NovaMinTM (bioactive glass, 45S5 composition). Methods. SRP, NovaMin particles, and placebo paste (PLA) which did not contain NovaMin, were immersed into a remineralization media (RS), which mimics the ionic strength of human saliva, for 3 days with different concentrations of alkaline phosphatase (ALP): 0, 25 and 75 U.L−1. Ion concentration profiles and pH were monitored by ICPOES and F− ion selective electrode. Remaining solids were collected by freeze-drying and their surfaces analysed. Results. Hydroxyapatite (HA) formed on the surface of BG alone (after 1 h) and in toothpaste (after 2 h), whereas PLA did not induce any precipitation. ALP cleaved MFP at different rates depending on the enzyme concentration. Increasing the concentration of ALP from 0 and 75 U.L−1 reduced the time of HA formation from 2 h to 24 h. However, the presence of fluoride induced the precipitation of fluorapatite. No evidence of fluorite (CaF2) was observed. The apatite formation ability of toothpaste can be assessed using the presented method

A unified in vitro evaluation for apatite-forming ability of bioactive glasses and their variants

The aim of this study was to propose and validate a new unified method for testing dissolution rates of bioactive glasses and their variants, and the formation of calcium phosphate layer formation on their surface, which is an indicator of bioactivity. At present, comparison in the literature is difficult as many groups use different testing protocols. An ISO standard covers the use of simulated body fluid on standard shape materials but it does not take into account that bioactive glasses can have very different specific surface areas, as for glass powders. Validation of the proposed modified test was through round robin testing and comparison to the ISO standard where appropriate. The proposed test uses fixed mass per solution volume ratio and agitated solution. The round robin study showed differences in hydroxyapatite nucleation on glasses of different composition and between glasses of the same composition but different particle size. The results were reproducible between research facilities. Researchers should use this method when testing new glasses, or their variants, to enable comparison between the literature in the future