I extremly recomend to read this papers:

http://www.ncbi.nlm.nih.gov/pubmed/20091655

http://www.ncbi.nlm.nih.gov/pubmed/18605525

http://www.ncbi.nlm.nih.gov/pubmed/7865074

the last one is a Classical paper.

Best Regards

There is a new lit. review paper on the subject just published, take a look at:

Best.

http://www.ncbi.nlm.nih.gov/pubmed/27101304

This can be useful:

Baysan A, Lynch E, Ellwood R, Davies R, Petersson L, Borsboom P. Reversal of primary root caries using dentifrices containing 5,000 and 1,100 ppm fluoride. Caries Research 2001;35:41–6.

Best Regards

Thank you for all your answers.

All the best