This countries TOP bomb inventer proved with his own teeth and tried to tell the usa government that teeth can be rebuilt and grow new enamel and naturally the usa ignored him, the fda promotes cancer and nothing more.
A crack is nearly impossible, while growing new enamel is SLOW, but can work. What I call Tooth & Gum Spray has helped enamel grow "faster". Basically by just supplying plant based minerals and the aid of cleansing the rock out of the blood stream/kidneys.
"IF" our kidneys are 100% clean, I will go on the record and suggest no human could EVER / EVER DIE!