title: A systematic review of definitions of periodontitis and methods that have been used to identify this disease.
abstract: OBJECTIVE
  To perform a systematic review and critical analysis of the definitions of periodontitis and the methods which have been used to identify and measure this disease.
  
  
  METHODS
  Relevant publications were identified after searching MEDLINE, EMBASE, SCISEARCH and LILACS electronic databases. Screening of titles and abstracts and data extraction was conducted independently by two reviewers. To be included in the review, studies were required to define periodontitis and to indicate how it was measured. Studies that related purely to gingivitis, and/or intervention studies, and/or studies where prevalence or severity of periodontitis was not a principal outcome were excluded.
  
  
  RESULTS
  From a total of 34,72 titles and abstracts, 104 potentially relevant full text papers were identified. Of these, 15 met the criteria for inclusion in the final stage of the review. The survey revealed heterogeneity between the studies in the measurement tools used, particularly the types of probes and the sites and areas of the mouth that were assessed. There was also heterogeneity in the use of clinical attachment loss (CAL) and pocket probing depth (PPD) as criteria for periodontitis. In the 15 studies, the threshold for a diagnosis of periodontitis when CAL was the criterion ranged from 2 to > or =6 mm and when PPD was used, from 3 to > or =6 mm.
  
  
  CONCLUSIONS
  This review has confirmed previous work which has suggested that epidemiological studies of periodontal diseases are complicated by the diversity of methodologies and definitions used. The studies that were reviewed utilized a minimum diagnostic threshold defining periodontitis, at a given site in terms of CAL of 2 mm and PPD of 3 mm.
authors.affiliation: UCL Eastman Dental Institute, London WC1X 8WD, UK.
authors.forename: Amir
authors.initials: A
authors.lastname: Savage
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Eaton
authors.forename: David R
authors.initials: DR
authors.lastname: Moles
authors.forename: Ian
authors.initials: I
authors.lastname: Needleman
mesh_terms: D006801:Humans; D017622:Periodontal Attachment Loss / Q000145:classification / Q000175:diagnosis; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000145:classification / Q000175:diagnosis; D010518:Periodontitis / Q000145:classification / Q000175:diagnosis*; D012107:Research Design