A New Fluoride Containing Bioactive Glass Additive For Toothpastes

Objectives: To characterize a new fluoride containing bioglass intended for use as a remineralising toothpaste.
Methods: The bioglass was synthesized by a high temperature melt quench route. The glass was ground to a <38 micron powder. The glass composition is given in Hill R and O’Donnell M “Multicomponent Glasses for Use in Personal Care Products” WO 2011/000866A2. The composition contains fluoride and a high phosphate content.
The glass (75mg) was immersed in 50ml of Tris buffer at pH 7.3 and in artificial saliva (AS) at pH 6.5. The solutions were filtered after the designated time period. The ion release into solution from the glass in Tris buffer over 24 hours was followed by ICP-OES for Si, Ca, Na, P and fluoride was measured using an ion selective electrode.
The precipitate from the Tris buffer and AS was collected, dried and characterized by XRD, FTIR, 31P and 19F MAS-NMR.
The ability of the bioglass when formulated as a toothpaste to occlude dentinal tubules was assessed using SEM and hydraulic conductance using a modified Pashley Cell, with mid coronal dentine discs cut from human molars. The hydraulic conductance was measured before and after application of the toothpaste.
Results: The BioMinF glass dissolved rapidly over approximately 6 hours releasing Na, Ca, PO43- Si and F-. The glass formed apatite in under 6 hours in Tris buffer and under 30 mins in AS as evidenced by the XRD and FTIR results. The apatite formed exhibited a peak in the ¹⁹F MAS-NMR spectrum at -103ppm. corresponding to fluorapatite. The SEM studies showed the dentinal tubules to be largely occluded and the apatite to form preferentially on the peritubular dentine. The percentage reduction in hydraulic conductance was >90%.
Conclusions: BioMinF is a promising additive for remineralising and sensitivity toothpastes. The prolonged release of fluoride in addition to calcium and phosphate and the formation of fluorapatite, as opposed to the more soluble hydroxyapatite formed with existing bioactive glasses are attractive features.