Method: A new commercial nano-sized HA and fluoride containing toothpaste and comparative toothpaste formula (HA only and F- only) as well as an oral rinse formula (HA and F-) were prepared. The nano-sized hydroxyapatite used was characterised by Secondary Electron Microscopy (SEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The remineralisation study was carried out by immersing enamel blocks in toothpaste/oral rinse treatment solutions (diluted by a factor of 1:10 and 1:2 with acetic acid) for 96 hours. Fluorapatite formation was investigated by 19F MAS-NMR. The ability of the test products to occlude the dentine tubules was evaluated by a 2 minute treatment on etched dentine disks followed by SEM analysis.
Result: Almost identical diffraction patterns for enamel and the nano-sized HA were obtained. The HA crystallite size was found to be 38 nm. The NMR spectra confirmed that no signs of fluoride in enamel control, demineralised enamel and specimen treated with HA only toothpaste alone. Fluorapatite formation was evident for the enamel specimens treated with HA and F- containing and F- only toothpaste. The present SEM study demonstrated that a combination of HA and F-provided superior tubule occlusion compared to the control toothpaste formula.
Conclusion: The nano-sized HA and fluoride containing toothpaste showed evidence of both fluorapatite formation and dentine tubule occlusion.