The present study aimed to clarify the relative impact of masticatory muscle pain, dynamic temporomandibular disc abnormality, and osteoarthritis (OA) on subjective pain intensity and daily life impairment of patients with temporomandibular disorders (TMD). The subjects consisted of 393 patients with TMD. Dynamic disc abnormality and OA were diagnosed by MRI examination. Palpation of the masticatory muscles was carried out. Also, pain intensity at rest and pain intensity during mastication were recorded using the visual analog scale, and the degree of disability in daily life impairment was evaluated using the scores of activities of daily living (ADL). A multiple regression analysis was performed to identify the significant associations between the outcome (dependent variable: pain intensity at rest or pain intensity during mastication or ADL) and the predictors (covariates: age, sex, presence of masticatory muscle pain, dynamic disc abnormalities, and presence of OA) after controlling simultaneously for potential confounders. Based on the result of multiple regression analysis for the pain intensity at rest, age (p=0.008) and the presence of masticatory muscle pain (p<0.001) were statistically significant explanatory variables. According to the result of multiple regression analysis for the pain intensity during mastication, age (p=0.034) and the presence of masticatory muscle pain (p<0.001) were statistically significant explanatory variables. The result of multiple regression analysis for ADL showed that the presence of masticatory muscle pain was a statistically significant explanatory variable (p<0.001). Therefore, the present study clarified that masticatory muscle pain significantly impacts clinical symptoms in patients with TMD. In addition, it was suggested that improvement of masticatory muscle pain might be the preferential therapeutic goal for patients with TMD.

TMDs are dysfunctions of locomotor organs such as TMJ and muscles used for mastication, and exercise therapy is reported to be useful for functional recovery. However, the technique and method of teaching exercise therapy according to the pathological condition of TMDs have not been clarified, and so it is necessary to increase the number of cases and evaluate each pathological condition in detail in order to establish the technique and teaching method. We report two cases: the first patient visited the hospital with the chief complaint of being unable to close her mouth at meal times, had left-sided temporomandibular disc derangement without reduction, and was unable to open her mouth wide at meal times. The second patient was diagnosed with left- and right-sided temporomandibular disc derangement with reduction, and exhibited mouth closure and opening during an opening/closing movement test. In both cases, we confirmed the position where the open state was impaired by reproducing the impaired state and instructed the patients to perform joint range of motion training as an exercise therapy aimed at increasing the range of motion from that state. Furthermore, when the TMJ was manually mobilized as an exercise therapy aimed at expanding its cavity and range of motion, the closure disorder and trismus disappeared in both cases. Based on these facts, in cases of temporomandibular joint disc derangement, it may be important to evaluate the amount of opening movement and the quality of opening and closing movements, and to clarify the problem and reflect it in exercise therapy instead of uniform exercise therapy.

We applied an occlusal appliance to a young patient with temporomandibular joint (TMJ) osteoarthritis and confirmed a good outcome based on long-term clinical and imaging diagnostic follow-up. Herein, we report a summary of the clinical course of the patient. A 14-year-old girl presented with the chief complaint of pain of the left TMJ area at mouth-opening. At the initial examination, tenderness of the temporal and masseter muscles was observed. In addition, we detected functional pain of the temporal and masseter muscles, and TMJ pain with crepitus resulted in the limitation of mouth opening. Computed tomography (CT) revealed abnormal thinning and roughening of the cortical bone on the bilateral condyles and hypoplastic-like change with flattening of the left condyle. On magnetic resonance (MR) images, a partial erosive change of the condyle and anterior disc displacement without reduction were observed in the left TMJ. In the right TMJ, anterior disc displacement with reduction was detected. Based on these findings, the patient was diagnosed with temporomandibular disorders (TMD) of types I, II, IIIa, IIIb, and IV, according to the decision tree of diagnostic criteria for temporomandibular disorders (DC/TMD). Serial treatments using a maxillary stabilization-type oral appliance, physical therapy and guidance on a daily basis were applied to reduce the overloading on the masticatory muscles and TMJ. These treatments allowed relaxation of the masticatory muscles and TMJ and stabilization of the occlusion. As a result, the preoperative TMD symptoms disappeared, and the range of mouth-opening reached the normal level after 4-months of treatment. Thereafter, the patient was followed up every 6 months and instructed to wear an oral appliance for sleep bruxism when necessary. Consequently, no recurrence of TMD symptoms was observed during 4-years of follow-up after the start of treatment. Moreover, on follow-up CT and MR images at that time, remodeling of the condyles and disappearance of the findings suggesting osteoarthritis were observed. Thus, the clinical course was considered to be comprehensively successful.