title: Periodontal disease and metabolic syndrome: a qualitative critical review of their association.
abstract: BACKGROUND
  Metabolic syndrome (MetS) is a conglomerate of several physical conditions/diseases that, as a group, increases the risk of mortality resulting from development of T2DM and cardiovascular diseases (CVD). These conditions/diseases include glucose intolerance/insulin resistance, hypertension, obesity, and dyslipidemia. The results from epidemiological studies suggest that there is an association between metabolic syndrome (MetS) and periodontitis, it is therefore important to understand the current status of the association and a possible contribution of periodontitis to MetS.
  
  
  OBJECTIVE
  This review will qualitatively analyze published papers on the association of MetS and periodontitis/periodontal disease to clarify the current status of the association and suggest future directions for studies which may unravel the causal relationship between them.
  
  
  RESULTS
  Of 309 papers related to MetS and periodontitis, 26 are original research papers that investigated the relationship/association between periodontal disease and MetS. Criteria used to assess periodontitis and MetS as well as overall study designs and patient recruitment criteria varied greatly among these studies.
  
  
  CONCLUSIONS
  All these studies demonstrated a positive association between periodontal disease and MetS. However, due to the heterogeneity of criteria to assess periodontitis and MetS and also paucity of longitudinal studies, it is difficult to determine the relative contribution of periodontitis to MetS. Age and the number of positive components of MetS appear to strengthen the relationship, however, incidence of each disease entity increases with ageing. Thus, mechanistic studies are also necessary to unravel the inter-relationship between periodontitis and MetS. In this regard, a use of animal models will be helpful as they are more uniform in regards to genetic background and have minimum confounding factors. Finally, development of accurate, quantitative assessment of gingival inflammation are necessary in order to determine the influence of periodontal disease on the development of MetS and its components.
authors.affiliation: Department of Periodontics, College of Dentistry, University of Illinois at Chicago, IL, USA. Electronic address: keiko@uic.edu.
authors.forename: Keiko
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Undergraduate Program, College of Dentistry, University of Illinois at Chicago, IL, USA.
authors.forename: Yale D
authors.initials: YD
authors.lastname: Cho
mesh_terms: D018450:Disease Progression; D006801:Humans; D024821:Metabolic Syndrome / Q000209:etiology*; D010510:Periodontal Diseases / Q000150:complications*; D012307:Risk Factors
keywords: Criteria; Metabolic syndrome; Periodontitis; Qualitative review