Medical and Oral Care in the 21st Century by the Department of Oral Medicine : A novel Therapeutic Strategy for Dry Mouth on the Basis of Molecular Mechanisms Involved in the Onset of the Disease

Japan became a super-aging society in 2007, and the aging rate is expected to increase further. This rapid aging of the population has impacted the structure of disease. In terms of oral health, this has resulted in an urgent need to shift from conventional “curative treatment”, which focuses on restoring dental morphology, to “curative and supportive treatment”, which focuses on restoring oral function in elderly and diseased patients. Diseases treated by the Department of Oral Medicine include oral mucosal diseases, salivary gland diseases (such as dry mouth), inflammatory diseases, neurological diseases, oral psychosomatic disorders, and taste disorders, among others. As many oral diseases are related to systemic diseases, the Department of Oral Medicine is a dental field adjacent to medical science. Therefore, the Department of Oral Medicine is responsible for perioperative oral function management and oral screening prior to the introduction of bone-modifying drugs in collaboration with medical doctors, and it also plays an important role in developing oral management plans according to the patient's disease and condition. The importance of the Department of Oral Medicine will continue to increase further. This review article focuses on dry mouth, a rising issue in the super-aging society, and describes research on developing novel treatments for Sjögren's syndrome (SS). C-X-C motif chemokine ligand 10 (CXCL10) is overexpressed in the labial salivary glands (LSGs) of patients with primary SS (pSS). Studies using human salivary gland cells have demonstrated that CXCL10 is secreted via the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway through interferon-γ stimulation in ductal cells. The potential of JAK inhibitors as therapeutic agents for pSS was evaluated by analyzing the LSGs of patients with pSS and immortalized normal human salivary gland cell lines. The results suggested that JAK inhibitors may be effective for treating dry mouth in patients with pSS. Treating dry mouth may improve the quality of life and contribute to a long and healthy life.