Periodontal diseases, such as chronic periodontitis, share common inflammatory risk factors with other systemic and chronic inflammatory disorders. Mucosal tissues, such as oral epithelia, are exposed to environmental stressors, such as tobacco and oral bacteria, that might be involved in promoting a systemic inflammatory state. Conversely, chronic disorders can also affect oral health. This review will summarize recent evidence for the interrelationship between chronic periodontitis and other prevalent chronic diseases such as cardiovascular diseases, diabetes, cancer and chronic respiratory diseases. The association with pregnancy is also included due to possible obstetric complications. We will focus on inflammatory cytokines such as TNF-alpha, IL-1, and IL-6, because they have been shown to be increased in patients with chronic periodontitis, in patients with chronic systemic diseases, and in patients with both chronic periodontitis and other chronic diseases. Therefore, an imbalance towards a proinflammatory immune response could underline a bidirectional link between chronic periodontitis and other chronic diseases. Finally, we highlight that a close coordination between dental and other health professionals could promote oral health and prevent or ameliorate other chronic diseases.

Although a number of inflammatory cytokines have been shown to be associated with periodontal pathogenesis, it is important to investigate further whether these biomarkers are associated with the degree of success in nonsurgical treatment of chronic periodontitis. The aim of the present study was to quantify the total levels of interleukin (IL)-1α, -1β, -6, -10 and tumour necrosis factor (TNF)-α in gingival crevicular fluid (GCF) of chronic periodontitis patients prior to and following nonsurgical periodontal therapy. In total, 52 GCF samples from disease sites of patients with chronic periodontitis, prior to and following periodontal therapy, and ten non-disease sites from non-periodontitis subjects, were collected and cytokine concentrations were determined using a multiplex method. Periodontal parameters, including bleeding on probing, probing pocket depth and the clinical attachment level, in all the sites were recorded. Untreated disease sites exhibited higher cytokine levels in the GCF when compared with the non-disease sites. Nonsurgical periodontal therapy resulted in a statistically significant decrease in the total levels of IL-1α, -1β and -6 in the GCF, but not in IL-10 or TNF-α. The results support the hypothesis that proinflammatory cytokines, including IL-1α, IL-1β and IL-6, are likely to be involved in the pathogenesis of periodontitis and are good markers to evaluate the success of nonsurgical therapy in disease sites of patients with periodontitis.