The increase in the average age of the population forces dentists and dental hygienists to deal with clinical scenarios typical of the elderly. In old people deep changes present both in systemic and oral health. These changes affect the anatomical and functional integrity of many tissues, such as the mouth. Impairment of patients' oral hygiene becomes manifested by local infections and promotes the pathogenesis of periodontal diseases. There is also a significant increase in autoimmune diseases, which are defined as disorders of the immune system that result in abnormal immune responses. Among the autoimmune diseases of medical interest we report a case of rheumatoid arthritis (RA) strictly related to periodontal disease.