title: [Advances in the study of indexes for periodontal diseases and their epidemiology: An overview]
authors.affiliation: Department of Oral Medicine, Ninth People's Hospital, School of Stomatology, Shanghai Second Medical University,Shanghai 200011, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Yang