Salivary cytokines as biomarkers of periodontal diseases

Research into biomarkers of periodontitis is driven by mainly three targets: to identify 'at risk' patients before periodontal tissue destruction occurs; to determine disease activity and progression; and to build up our understanding of this complex disease with the purpose of finding new therapeutic targets. Whilst blood and gingival crevicular fluid were previously the biological samples of choice, saliva has recently gained more attention as a readily accessible oral fluid which has a mediator profile similar to that of serum and gingival crevicular fluid. The aim of this paper was to give a comprehensive overview of salivary cytokines in periodontitis, highlighting extensively studied cytokines such as interleukin-1beta and interleukin-6, but also cytokines that have been the subject of only a few studies and which warrant further investigation. Cross-sectional and longitudinal studies of salivary cytokines, and the potential of cytokines as periodontitis biomarkers, are evaluated. Finally, a discussion of potential confounding factors, such as concurrent systemic diseases and smoking, is presented.