Rauen, C. A.; Chidoski Filho, J. C.; Bittencour, B. F.; Gomes, G. M.; Gomes, J. C.; Gomes, O. M. M. Effect of Bleaching Agents Containing Fluoride or Calcium on Enamel Microhardness, Roughness and Permeability. Braz. J. Oral Sci. 2016, 14, 262-266.