Periodontitis is an oral disease comprising a group of inflammatory conditions affecting dentition supporting structures, including the periodontal ligament, alveolar bone, and gingival tissues. The host response plays a critical role in periodontal tissue breakdown. Whereas the activity of periodontal pathogens is required, their presence is not sufficient to account for the initiation and progression of periodontal disease. Lipopolysaccharide, a key component of the outer membrane of Gram-negative bacteria, stimulates host cells to produce a number of proinflammatory cytokines such as tumor necrosis factor alpha, interleukin-1, and interleukin-6. It also stimulates the production of other inflammatory mediators, such as prostaglandin E2 and nitric oxide. This inflammatory cascade promotes metalloproteinase matrix release from host tissues and causes deleterious effects in the extracellular matrix and alveolar bone. Periodontitis starts as a local infection, but the triggering of a chronic inflammatory cascade increases the susceptibility to acquire infectious diseases and other serious pathological conditions such as cardiovascular disease, mental disorders (e.g., depression), and diabetes. Additionally, frequent environmental exposure to stress, smoking, alcoholism, and drugs of abuse predispose the host to acquire and/or exacerbate the deleterious effects of periodontal disease. Therefore, the present issue attempts to discuss new approaches to prevent and treat periodontitis and its deleterious side effects.

In summary, a local inflammatory process, like the one that takes place during the early stage of periodontal disease, can reach a systemic dimension affecting the etiology of several other pathological conditions including the ones mentioned above. Therefore, we invite investigators to contribute original research and review articles to expand the understanding of periodontitis, a chronic infectious/inflammatory process that can alter the homeostasis of the whole organism in a severe manner.

Potential topics include, but are not limited to:

• Epidemiology of periodontal diseases: incidence, prevalence, geographical distribution, and comorbidities
• Risk factors for periodontitis
• Periodontitis and cardiovascular disease
• Periodontitis and systemic infectious diseases
• Periodontitis and diabetes
• Stress, mental disorders and periodontitis
• Periodontitis and tuberculosis