We reviewed temporomandibular joint disorders in childhood, using several references including our own data, with the following results.

･The prevalence of signs and symptoms of TMD in children has not clearly increased in recent decades. The main symptom is a clicking sound starting from low grades in elementary school, which increases gradually in prevalence with age.

･The clicking sound of each child varies as they grow up during elementary school years. The clicking sound persists in the following year in only about half of children. The sound persists among a larger percentage of junior high school children.

･There are some reports that pediatric TMD inhibits the growth of the mandible. It has been shown that this inhibition may occur on the side with articular disc disorder and/or osteoarthrosis of TMD.

By accumulating data through more detailed evaluations on the pediatric version of DC/TMD in future, we intend to conduct a more accurate analysis of temporomandibular joint disorders in childhood.

The basic management of TMD should begin with an explanation of the pathophysiology and self-care instruction, followed by non-invasive treatment, mainly physical therapy, pharmacotherapy, and appliance therapy. One of these conservative interventions, appliance therapy, has been reported to be effective for short-term pain relief, especially for myalgia, according to a 2017 meta-analysis, and we can confidently recommend this appliance therapy for these patients.

On the other hand, looking back at this appliance therapy from a prosthetic point of view, we have applied this occlusal appliance to a wide range of treatments, although the evidence is not yet well established. It is difficult to continue treatment without an occlusal appliance, especially when the occlusal height is elevated or in cases of acquired anterior open bite associated with temporomandibular joint osteoarthritis.

This paper focuses on three points: 1) TMD symptoms that can be effectively treated with appliance therapy, 2) symptom-specific methods of using occlusal appliances, and 3) application to cases of acquired anterior open bite associated with morphological changes in the temporomandibular joint from a prosthetic standpoint.

Since the pathology of temporomandibular disorders is diverse, it is necessary to provide prescriptions and specialized treatment through medical cooperation. In addition, it may be desirable to shift to treatment using a special oral appliance (OA), and when selecting a treatment method such as appliance therapy in clinical practice, it depends on the experience of the operator. This paper focuses on appliance therapy among various treatment methods and explains the program for selecting OA according to the pathology of masticatory muscle pain disorder and transitioning to the end of treatment. Intermittent lock, which is a type of temporomandibular joint disc disorder (Type IIIa: anterior disk displacement with reduction), shows pain in the temporomandibular joint and disturbance of mouth opening or mastication when locking occurs. Patients with intermittent lock often suffer in daily life and should be treated. Therefore, this paper introduces the clinical treatment and delves into appliance therapy.

Objective: In order to evaluate the validity of clinical examinations of bruxism commonly used in practice, we compared the results of clinical examinations with those of quantitative evaluations. Furthermore, we compared sleep and awake bruxism in clinical and quantitative evaluations.

Method: Thirty-two participants who provided informed consent to undergo bruxism examinations were selected from among the resident doctors and students at the Nippon Dental University Niigata Hospital. Of these, 23 were subjective bruxers and nine were subjective non-bruxers.

For the clinical examination of bruxism, 1) interviews, 2) clinical signs and symptoms, and 3) behavioral self-records of the participants were evaluated. For the quantitative examinations, the GrindCare^® single-channel portable electromyograph (Sunstar) was used.

The effectiveness of the clinical examinations compared to the quantitative examinations was determined by correlation analysis between the results of the two examinations. To compare between sleep and awake bruxism, Wilcoxon's signed rank test was used.

Results: The correlation between the clinical and quantitative examinations for sleep bruxism was low, except for clinical signs and symptoms which exhibited a weak association with quantitative examination results. In awake bruxism, clinical examination results did not correlate with quantitative examination results. Awake bruxism was significantly more common than sleep bruxism according to the interview results. In contrast, other examinations did not identify significant differences between awake and sleep bruxism.

Conclusion: The correlation between the clinical and quantitative examinations was weak with one exception. Therefore, the relevance of clinical examination for bruxism is considered to be generally low. We conclude that if an accurate evaluation of bruxism is needed, a quantitative examination, such as using an electromyogram, should be used.

Purpose: A model that expresses the movement of the mandibular condyle during mouth opening was developed. Using this model, the accuracy of measuring mandibular condyle movement in X-ray images was evaluated.

Methods: A robotic system to replicate the condylar movement of the TMJ was developed to evaluate the geometric elements of the appropriate X-ray projection to observe the movement of the condyle. Then, the linear distance of condylar movement was measured in the panoramic radiograph (TMJ imaging mode) and lateral oblique radiograph (Schüller method). Five dried mandibles (ten TMJs) were used as the objects to be imaged. The distances of condylar movement in the radiographs were compared with the actual movement distance of the dried mandibular condyles. The amount of error in the radiographic measurement value was calculated based on the actual measurement value and the magnified factor of radiographs.

Results and Conclusion: Using the robotic system and Schüller method radiograph, the mouth-opening movement was imaged by dividing it into 13 frames from the closed position to the maximum opening amount of 40 mm. The median condylar movement distance of the ten temporomandibular joints was 19.53 mm in actual measurement, 14.38 mm in the Schüller method, and 18.81 mm in panoramic TMJ imaging mode. The amount of error in the radiographic measurement was 3.34 mm in the panoramic TMJ imaging and 5.32 mm in the Schüller method. The results of this study suggested that panoramic TMJ imaging is superior to the Schüller method in the accuracy of measuring mandibular condylar movement.