Periodontal disease Deposits on teeth surface e dental plaque e soft mucinous deposits SO ft o stains calculus hard 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 6 Deposits on teeth surface  dental plaque  soft mucinous deposits  stains  calculus soft hard Periodontal Disease