What the pH the enamel make complete remineralization:
a. 3.5
b. 4.5
c. 5.5
d. 6.5 ***
When the pH returns to pH 5.5 or above, the saliva which is supersaturated with calcium and phosphate, forces mineral back into the tooth.7 Fluoride adsorbs to the surface of the partially demineralized crystals and attracts calcium ions. This new surface veneer takes up fluoride preferentially from the solution around the crystals and excludes carbonate
It is called Stefan curve