Early dentin caries under intact enamel surface Translucent zone(透明层) Sclerotic zone(硬化层) Whitlockite or Octacalcium phosphate Department of Oral Pathology, Shandong University 6 http://1.51.214.13Department of Oral Pathology, Shandong University 6 http://1.51.214.13  Translucent zone (透明层) Sclerotic zone (硬化层) Whitlockite or Octacalcium phosphate