In Japan, the number of neurological diseases such as Parkinson's disease will increase with the recent super-aging of the population. Various neurological disease conditions such as extrapyramidal diseases, pyramidal tract diseases, and muscular diseases can cause temporomandibular joint dislocation. The pathophysiology of temporomandibular joint dislocation is classified into two mechanisms as follows: incoordination of the temporomandibular muscles due to disorder of the extrapyramidal system or the cerebellum, and muscle weakness and atrophy of the temporomandibular muscles. The close association between these disease conditions and temporomandibular joint dislocation is reviewed.

The pathological condition of masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) remains unclear. We are conducting basic research on MMTAH in collaboration with several researchers. To accomplish the basic research, we need three factors: ideas, scientific research funds and human resources. Through collaborative research it is possible to compensate for those factors which clinical researchers sometimes do not have. This paper outlines our research and how we have collaborated for almost ten years. We also introduce the prospect of translational research for masticatory muscle tendon-aponeurosis hyperplasia.

Temporomandibular joint function is one of the functions that contributes to oral health, and its deterioration certainly leads to deterioration of the functioning of the oral cavity. Accordingly, managing the temporomandibular joint function in order to manage the functioning of the oral cavity is conducted as part of "oral health management".

It is important for dentists to provide management of oral cavity function so as to maintain the temporomandibular joint function at all ages (life stages); this can be considered as oral health management.

The concept of oral frailty will become increasingly important for oral health management. If the oral cavity is managed in line with concept of oral frailty and oral health management is applied throughout life according to individual health conditions, underlying diseases and so forth, then the necessary medical care and health services can be provided to all citizens.

Health can be improved by providing regular dental checkups and regular consultations by dentists. To do so, it is necessary to nurture the health literacy of citizens to help them understand and choose to participate in proper dental health checkups and regular consultations by dentists.

While keeping these matters in mind, we hope that dentists in dental care institutions will establish a system to provide dental care including health services in each local community in cooperation with their staff such as dental hygienists.

Diffuse sclerosing osteomyelitis (DSO) is a type of refractory osteomyelitis marked by repeated acute exacerbation. It may also be partially related to SAPHO syndrome. DSO is often accompanied by trismus, and due to its similar presentation, it is considered a differential disease of temporomandibular joint disorder (TMD). Here, we describe a patient who exhibited DSO of the mandible with TMD.

A 20-year-old woman was referred to our department because of right TMJ pain and trismus. The initial examination revealed a symmetrical facial appearance, trismus, and tenderness and pain in the right TMJ when opening the mouth. We made a diagnosis of TMD and performed appliance therapy for 2 months, which slightly increased her mouth opening. During this period, the patient was treated with antibiotics and corticosteroid at another hospital for uveitis, and TMJ pain was improved slightly. Based on this finding, we suspected infectious inflammatory disease and ordered radiographs. However, the images revealed only a small, localized osteosclerotic lesion on the right mandibular ramus.

Two years after the initial visit, the patient returned and reported having intermittent exacerbations of symptoms. Radiographs were performed and revealed extended osteosclerotic lesions, resulting in a diagnosis of DSO of the mandible. We began a course of treatment with bisphosphonate drugs, and her symptoms improved. The disease has remained stable for 1 year and 2 months after finishing treatment.