Influence of salivary macromolecules and fluoride on enamel lesion remineralization in vitro

The aim of this study was to investigate the influence of salivary macromolecules on enamel lesion remineralization in the presence or absence of fluoride. Paraffin-stimulated whole saliva was centrifuged, and the supernatant was dialyzed in 1,000 molecular-weight cutoff dialysis tubes, first against a phosphate buffer and then against a mineral solution containing Ca and phosphate. Artificial subsurface lesions of human enamel, created in pH 4.5 acetate buffer, were remineralized for 28 days in 4 remineralizing solutions: group C--mineral solution as a control; group S--mineral solution + dialyzed saliva; group F--mineral solution + 1 ppm F; group SF--mineral solution + dialyzed saliva + 1 ppm F. Changes in relative mineral concentration in the lesions were assessed by transverse microradiography. The results showed statistically significant mineral gains in the lesion body in groups C (DeltaZ = 3,254 +/- 1,562% x microm) and SF (DeltaZ = 2,973 +/- 1,349% x microm), but not in groups S (DeltaZ = 5,192 +/- 1,863% x microm) and F (DeltaZ = 4,310 +/- 1,138% x microm) compared with the baseline group (DeltaZ = 5,414 +/- 461% x microm). It was also found that the mineral density at the surface layer in group F (75.0 +/- 15.7%) was greater than that in the baseline group (30.1 +/- 12.3%) with statistical significance, but not in group SF (39.9 +/- 16.5%). It was concluded that the macromolecules inhibited lesion remineralization fundamentally but that these molecules, in the presence of fluoride, seemed to play an important role in the continuation of remineralization by reducing mineral gains at the surface layer.