We aim to study the kinetics of phase formation and transformation during the crystallisation of apatite from amorphous degradable bioactive glasses used as a treatment for dentine hypersensitivity in toothpaste. We propose to study in situ the early-stage nucleation and ripening kinetics together with the time dependent crystallisation and phase transformation in real time using combined neutron diffraction and SANS. Uniquely, this will allow us to determine the mechanisms of nucleation and crystallisation in these materials, and to test our hypothesis that precursor Octacalcium Phosphate (OCP) and possibly other intermediate phases form at the very early stages of crystallisation prior to apatite formation as has been suggested by our solid state 1H NMR spectra.