The etch gel is the materials to etch the teeth prior to treatment, which is composed of 24.5 % H3PO4, 9.0 % SiO2, 1.5 % Al2O3 and 63.52 % H2O in weight.

• 酸蚀剂是对牙齿进行预先蚀刻处理所使用的材料，它是由重量百分比为24.；5%25的H3PO4、9