Enamel slabs were prepared from sound human premolars which had been extracted for orthodontic treatment and etched with 0. 1%(w/v) citric acid. We divided them into four groups to test the effects of the four remineralizing methods. One group were treated with stimulated saliva for 30 minutes, another with 0,05% sodium fluoride solution for 2 minutes, the third with the same solution for 30 minutes and the fourth with ordinary liquid cow´s milk for 30 minutes, and the microhardness of them were measured with Vicker´ s microhardness numbers. Then the whole samples were emulsed in stimulated saliva and the microhardness of them were measured after 3 and 6 hours. The remineralizing effects of the treatments were analysed and the results are as follows.
1. The microhardness increase of eroded enamel surface after the four kinds of remineralizing treatment were compared, and the effect of milk treatment was significantly `higher than the effects of other treatments(p ( 0.01).
2. After the remineralizing treatments, whole samples were emulsed in stimulated saliva and microhardness of them were measured. The increase of microhardness in the four groups were all significant after 3 and 6 hours(p ( 0.01). The microhardness increase of the groups in this step were statistically not different, but the microhardness number of the milk treatment group was the highest among the four groups like before(p ( 0.01) because the remineralizing effect of the milk treatment was maintained.
It is concluded that the 30 minutes of milk treatment has significantly higher remineralization effect on eroded enamel surface than the other treatments used in this study, saliva or 0.05% sodium fluoride solution. Therefore, if the methods that milk can be contact with enamel surface as long as possible would be developed, remineralization effect of the milk can efficiently support the salivary function.
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