Laboratory studies on the demineralization and remineralization of human enamel in relation to caries mechanisms.

These studies demonstrate that a significant degree of remineralization of both natural and artificial lesions can be achieved in vitro. Changing the calcium concentration of the synthetic calcifying fluid had a significant effect on both the degree of remineralization achieved and the site of the lesion affected. When the calcifying fluid contained 3 mM calcium, remineralization occurred mainly in the superficial part of the lesion. When a 1 mM calcium calcifying fluid was used on adjacent halves of the same lesion, remineralization occurred throughout the entire depth of the lesion. Under these conditions there was a highly significant reduction in lesion size accompanied by an increase in orientated mineral crystals. The crystals were found to have diameters several times larger than those found in the sound enamel, most probably produced as a result of crystal growth. These results have significance in terms of both mechanisms of hard tissue repair and the possible eventual development of an agent for caries prevention.