Surfactant-modified β-TCP: structure, properties, and in vitro remineralization of subsurface enamel lesions

A hybrid material comprised of beta-tricalcium phosphate (beta-TCP) and sodium lauryl sulfate (SLS) was prepared using a mechanochemical process, examined using particle size analysis, IR spectroscopy, P-31, Na-23, and C-13 solid-state NMR spectroscopy, and calcium dissolution experiments, and probed for in vitro remineralization of subsurface enamel lesions. Our results suggest that while the P-31 environments of beta-TCP remain unchanged during solid-state processing, there is noticeable shifting among the SLS Na-23 and C-13 environments. Therefore, given the structure of beta-TCP, along with our IR examinations and calcium dissolution isotherms, SLS appears to interface strongly with the cation deficient C-3 symmetry site of the beta-TCP hexagonal crystal lattice with probable emphasis placed on the underbonded CaO3 polyhedra. To demonstrate the utility of the surface-active TCP material in dental applications, we combined the TCP-SLS with 5,000 ppm F (NaF) and evaluated the remineralization potential of subsurface enamel lesions via an in vitro remineralization/demineralization pH cycling dental model. Using surface and longitudinal microhardness measurements, the TCP-SLS plus 5,000 ppm F system was found to significantly boost remineralization of subsurface enamel lesions, with microhardness values increasing up to 30% greater than fluoride alone.