Psoriasis is a chronic, inflammatory, and recurrent skin disease. As with periodontitis, the development and progression of lesions depend on immunological, genetic, and environmental factors. This systematic review was designed to answer the question: “Is there a relationship between psoriasis and periodontal disease?”. Following the inclusion and exclusion criteria, sixteen studies were included in this systematic review (according to PRISMA statement guidelines). Based on the meta-analysis, psoriasis patients showed a more than two-fold increase in the odds of periodontal disease. Almost one-third of these patients suffered from periodontitis of varying severity. Despite the heterogeneity of the included studies, psoriasis is associated with a higher risk of periodontitis, and especially with advanced progression.

Autoimmune thyroid disease (AITD) is a dysregulation of the immune system that causes an attack on the thyroid gland. Two major clinical manifestations are Hashimoto’s thyroiditis and Graves’ disease. Saliva performs many functions and, importantly, has the potential for easy, non-invasive diagnostics of several systemic disorders. This systematic review was designed to answer the question whether salivary alterations are reliable for the diagnosis of autoimmune thyroid diseases. Following the inclusion and exclusion criteria, fifteen studies were included. Due to their heterogeneity, saliva analysis was divided into two subgroups: quantitative assessment analysing salivation and qualitative assessment concerning potential salivary biomarkers for AITD. In addition to detecting altered levels of thyroid hormones and antibodies, salivary changes were also observed in the concentrations of total protein, cytokines and chemokines, as well as markers of oxidative status. According to the saliva flow rate values, significantly reduced saliva secretion was observed in patients with HT. In conclusion, it is not possible to unequivocally state if salivary biomarkers can potentially be used in autoimmune thyroid disease diagnosis. Therefore, further investigations, including salivation disorders, are necessary to validate these findings.