Periodontal disease ●软垢( soft mucinous deposits) Department of Oral Pathology, Shandong University http://course.sdu.edu.cn/oralhistopath.htmlDepartment of Oral Pathology, Shandong University http://course.sdu.edu.cn/oralhistopath.html 10  软垢(soft mucinous deposits)： Periodontal Disease