Jung H, Chung S, Ahn Y, Shin K, Cho J.  The effect of dentifrice including dental type silica, tocopherol acetate, sodium fluoride and sodium pyrophosphate on mineral density in enamel.  Journal of Korean Academy of Oral Health 2020;44:180-186.  https://doi.org/10.11149/jkaoh.2020.44.4.180