Smooth surface caries e Site of attack On the approximal surface On the gingival third of the buccal and lingual surfaces Department of Oral Pathology, Shandong University http://1.51.214.13Department of Oral Pathology, Shandong University 4 http://1.51.214.13 Site of attack： On the approximal surface; On the gingival third of the buccal and lingual surfaces