Results :These observations showed that areas of slight decalcification were limited to some enamel rod after the acid etching for the fird time and the number of cellular structure was low.

• 结果： 镜下的观察显示，第一次酸处理后只是部分釉柱的轻度脱钙，蜂窝样结构少而不均匀。第二次酸处理后牙釉质表面蜂窝样结构密集而规则。