脱灰エナメル質のフッ素取り込みと再石灰化に及ぼすカルボキシメチルセルロースの効果

Abstract

The effect of carboxymethylcellulose (CMC) on enamel remineralization was investigated in in vitro. CMC is a component of artificial saliva substitutes and may be considered as a model molecule for the salivary mucins. Human dental enamel slabs (N=60) were demineralized for 12 hours by immersion in a demineralizing solution containing 0.1M lactic acid, 3.0mM Ca, 1.8mM P, and 1% CMC at pH 4.5. After demineralization, the enamel slabs were immersed in four groups of remineralizing solutions for 10days (20ml/slab), which contained 3.0mM Ca, 1.8mM P, and 150mM NaCl at pH7.0, with and without 1% CMC and 3ppm fluoride, that is, (1) 0% CMC/0ppm F (C0F0), (2) 1% CMC/0ppm F (C1F0), (3) 0% CMC/3ppm F (C0F3), and (4) 1 % CMC/3ppm F (C1F3). After remineralization, the degree of remineralization were evaluated by chemical analysis for Ca amount, Ca/P ratio, and fluoride uptake, and by microradiography using calculated mineral vol%. The remineralized enamel slabs were treated with 1.0N HClO4 solution to evaluate the acid resistance and also the mineral vol% was reevaluated by microradiography. The following results were obtained.1) The fluoride uptake in group C1F3 was about two times higher than that of group C0F3 for the first to fourth layers (p<0.05). 2) According to the microradiography evaluation of group C1F0, the lowest mineral vol% was evident. Groups C0F0, C0F3, and C1F3 were obviously remineralized, but the mineral vol% of group C0F3 was lower than that of groups C0F0 and C1F3. 3) A radiopaque zone, indicating acid resistance, was not found in group C1F0, but the other three groups showed acid resistant zones. The microradiographic characteristics of the acid resistant zone in groups C0F3 and C1F3 were uniform. This zone was formed through the remineralized area, particularly at the surface and bottom layer of the remineralized area. In group C0F0, however, such uniformity was not found. 4) The Ca amount and Ca/P ratio were not sufficient to evaluate the degree of remineralization.These results suggest that not only the CMC molecule, which is relatively large (50, 000-12, 000), inhibits remineralization without fluoride ions, but also, that the CMC molecule promotes fluoride uptake and the degree of remineralization with fluoride ions.