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.

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It is common knowledge for dentists that sleep bruxism can produce destructive symptoms in the stomatognathic system, such as tooth wear. However, if it is not clear whether those symptoms are truly caused by sleep bruxism, overtreatment may result. The American Academy of Sleep Medicine has classified the diagnosis by polysomnography as “Definite sleep bruxism”, “Probable sleep bruxism” by clinical signs, and “Possible sleep bruxism” by questionnaire. Clinically, the diagnosis should be made through objective evaluation using a wearable electromyograph or the International Classification of Sleep Disorders third edition criteria for diagnosis based on clinical signs (tooth grinding sounds during sleep and abnormal tooth wear or/and morning jaw symptoms). In addition, the underlying causes of sleep bruxism should be investigated. If it is associated with a background disease, such as secondary sleep bruxism, treatment should proceed in collaboration with medical professionals. If augmenting factors are present, sleep hygiene instructions should be provided. If these treatments are unsuccessful, a well-fitting, properly adjusted occlusal appliance (stabilization-type appliance) may be applied. However, once symptoms have improved, the patient should proceed to discontinue the occlusal appliance.

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Purpose: To explore the use of ultrasound (US) for quantitative and qualitative assessment of muscles (especially the tongue) in dentistry, we performed investigations using muscles of the lower extremities. These muscles are often used to assess skeletal muscles in general. We aimed to determine whether there was a correlation between quantitative and qualitative assessments of lower extremity muscles using diagnostic US and computed tomography (CT) scans in adults.
Procedure: We conducted a search for English articles published in PubMed and Scopus from its inception up to October 18, 2022. We used a combination of the keywords “muscle,” “ultrasonography,” and “computed tomography” for the search. Additionally, we manually searched through relevant journals and search engines.
Main findings: After applying the inclusion criteria, we ultimately selected seven studies for inclusion in this review. These seven studies focused on muscle mass and involved ultrasonographic evaluations of muscle thickness and cross-sectional area as well as CT evaluations of muscle volume and cross-sectional area. Two studies also evaluated muscle quality using echo intensity (EI) for US assessment and CT values for CT assessment. In three of the seven studies, there was a significant correlation between the US and CT results. Three studies also determined an intraclass correlation coefficient (≥0.8 in all three) to determine the correlation between CT and US. In both studies that additionally assessed muscle quality, a strong correlation was observed between CT and US measurements.
Conclusion: Our results suggest that US can be used to perform high quality assessments of lower extremity muscles and muscle mass in healthy individuals and patients with mild or moderate disease. In the future, high quality research on the tongue is needed for application to the field of dentistry.

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