To favour remineralisation over demineralisation, you really need to attack both sides of that equilibrium. Obviously, the most important factor to enhance remineralisation is fluoride. It speeds up the process dramatically. That is because of the high level of cation-seeking potential for the element. It is the most electro-negative of all elements and therefore is searching for calcium or cations and it favours the formation or the precipitation of apatite crystals and favours remineralisation.
At the same time, you need to also decrease the amount of demineralisation; that is the attack that occurs every time we eat a meal, have a snack, drink a coffee with sugar in it or a Coke or whatever. So the best way to do that is (1) reduce the frequency with which we have those attacks, the number of times we snack in a day, and (2) the second factor is improve oral hygiene. The better the oral hygiene the less the amount of damage. There is much more acid produced in an older plaque by a log rhythmic factor as compared to a plaque that is say 12 hours or less of age. So brushing, for example, twice a day, flossing and so on, greatly enhances the potential for remineralisation by decreasing the amount of demineralisation.
When plaque pH rises above 5.5, remineralisation can start to occur. Above this pH, interbacterial plaque fluid and saliva return to being saturated, and then supersaturated, with respect to hydroxyapatite.
Remineralisation of dental lesions requires the presence of partially demineralised crystals that can grow to their original size when they are exposed to fluid that is supersaturated with respect to hydroxyapatite minerals. Because the carious lesion contains partially demineralised crystals, it is possible for it to become remineralised. Considerable remineralisation of the surface of caries lesions has been observed. However, due to slow diffusion, it is difficult to maintain a high level of supersaturation in deeper layers of enamel, so remineralisation of the lesion body can be quite slow, if it occurs at all.18 The surface layer of the lesion that has been remineralised, therefore, prevents the lesion body from being further demineralised, but it also inhibits its remineralisation.1