Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Background

Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a relatively newly identified clinical condition that manifests as trismus with a square-shaped mandible. Herein, we report a case of MMATH that was initially misdiagnosed for polymyositis due to trismus and simultaneous lower limb pain, with literature review.

Case presentation

A 30-year-old woman had a history of lower limb pain after exertion for 2 years. Initial physical examination had been performed at the Department of General Medicine in our hospital. There was also redness in the hands and fingers. Although polymyositis was suspected, it was denied. The patient visited our department for right maxillary wisdom tooth extraction.

Clinical examination revealed that the patient had a square-shaped mandible. The maximal mouth opening was 22 mm. There was no temporomandibular joint pain at the time of opening. Furthermore, there was awareness of clenching while working. Panoramic radiography revealed developed square mandibular angles with flattened condyles. Computed tomography showed enlarged masseter muscles with high-density areas around the anterior and lateral fascia. Magnetic resonance imaging also showed thickened tendons and aponeuroses on the anterior surface and inside bilateral masseter muscles. Finally, the patient was diagnosed with MMTAH. Bilateral aponeurectomy of the masseter muscles with coronoidectomy and masseter muscle myotomy was performed under general anesthesia. The maximum opening during surgery was 48 mm. Mouth opening training was started on day 3 after surgery. Histopathological examination of the surgical specimen showed that the muscle fibers were enlarged to 60 μm. Immunohistochemistry testing for calcineurin, which was associated with muscle hypertrophy due to overload in some case reports, showed positive results. Twelve months after surgery, the mouth self-opening and forced opening were over 35 mm and 44 mm, respectively.

Conclusions

Herein, we report a case of MMATH. Lower limb pain due to prolonged standing at work and overload due to clenching were considered risk factors for symptoms onset of MMATH.

DOI： 10.1186/s40902-023-00386-6

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Other Link： https://link.springer.com/article/10.1186/s40902-023-00386-6/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Lip closing functions have never been evaluated from the viewpoint of elastic properties. OBJECTIVES: The purpose of the present study was to investigate the behavior of the lower orbicularis oris muscle during a button-pull exercise to measure lip closing force and quantitatively evaluate its elastic properties using sonographic elastography. METHODS: Appropriate compression loads for elastography were randomly measured on one of three types of acoustic couplers on three examiners. Compression tests were performed on three types of acoustic couplers within the appropriate compression load. Using the acoustic coupler with the lowest elastic modulus, the strain ratio of the lower orbicularis oris muscle during lip closing was measured, and elastography was performed on six males under tension loads of 0-8 N. RESULTS: The intraclass correlation coefficient (1, 3) for the tension load of 0 N was 0.81. Elastography showed that the strain ratio values increased significantly (p < 0.05) as the tension load increased. CONCLUSIONS: Combining the data obtained from lip closing test devices and sonographic elastography enabled the muscle performance to be evaluated objectively and accurately.

DOI： 10.3233/BME-201101

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVES: The present study was performed to investigate the mineral density distribution in enamel and dentin for both permanent and primary teeth and to establish the standard density per tooth type using micro-computed tomography (CT). METHODS: Fifty-seven extracted human teeth (37 permanent, 20 primary) were evaluated in the present study. The enamel and dentin mineral densities in the extracted teeth were measured using micro-CT. Cubic regression curves were used to determine the mineral density distribution in the enamel and dentin for each tooth type. RESULTS: The mean values, distributions, and regression equations of the mineral densities were obtained. The mean mineral density values for permanent enamel and dentin were significantly higher than those for their primary counterparts for each tooth type. CONCLUSIONS: In the present study, we demonstrated the distribution of mineral density in sound enamel and dentin and attempted to determine the standard mineral density for each tooth type using micro-CT. The mineral density distributions found in this study contribute to our understanding of the mechanical properties of enamel and dentin. A positive correlation suggests that the systemic bone mineral density could be predicted based on the analysis of exfoliated teeth, such as in patients with hypophosphatasia. The present results may be useful in establishing a numerical standard for the mechanism involved in root fracture and for early detection of root fracture risk.

DOI： 10.1007/s11282-018-0315-2

PubMed

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Language：Japanese   Publisher：The Japanese Society of Dysphagia Rehabilitation  

<p> The causes of xerostomia are diverse and include Sjӧgren's syndrome, psychological stress, and side effects of medications. In some patients, the cause may be multifactorial (e.g., psychological stress and side effects of medications, or irradiation and mouth breathing). No unified diagnostic criteria for xerostomia have been established; therefore, the criteria used in clinical practice differ among dentists. Furthermore, it is difficult to diagnose multiple causes using a flow chart-type diagnostic sheet. Therefore, we created a new diagnostic sheet that is useful for multiple causes of xerostomia. In the present study, we used this sheet to diagnose new patients in our xerostomia clinic. The cause of xerostomia was an autonomic nerve disturbance (61.4%); other causes included the side effects of medications (57.3%), mouth breathing (36.8%), Sjӧgren's syndrome (15.9%), dental psychosomatic disorder (14.5%). The degree of coincidence of diagnosis was very high (κ: 0.99, <i>p</i>＜ 0.001). A total of 164 patients (74.5%) had plural diagnosis. The results of this study indicate that multiple factors are likely related to xerostomia. Therefore, the use of a diagnostic sheet that can facilitate multiple diagnoses in patients with xerostomia seems necessary. </p>

DOI： 10.32136/jsdr.22.2_153

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Other Link： http://search.jamas.or.jp/link/ui/2019231072

Language：Japanese   Publisher：Japanese Society for Oral and Maxillofacial Radiology  

<b>Objective</b>: In order to establish a response indicator for predicting the treatment effects of oral appliances in patients with obstructive sleep apnea syndrome, we examine the utility of synchronous real-time dynamic ultrasound monitoring of the motion of the hyoid bone and the mandibular condyle during anterior mandibular movement.<br><b>Materials and methods</b>: Eight healthy volunteers, including three females and five males, were recruited for this study. None of the subjects had a history of sleep-related disorders. The synchronous real-time dynamic monitoring of mandibular protrusion was performed using two ultrasound systems with dedicated intraoperative probes. We measured five consecutive movements of the lateral portion of the mandibular condyle as an indicator of the anterior movement of the mandible and five consecutive movements of the lateral edge of the hyoid body as an indicator of the caudal movement of the hyoid bone.<br><b>Results</b>: The variation coefficient of the response ratio, which was defined as the ratio between hyoid caudal movement and mandibular anterior movement, was smaller than the amount of hyoid caudal movement in every subject. The mean amount of hyoid movement ranged from 2.0mm to 9.0mm, and the mean response ratio ranged from 0.28 to 0.87. The mean variation coefficient ranged from 5.2% to 19.5% for hyoid movement and from 4.6% to 16.1% for the response ratio.<br><b>Conclusion</b>: It was speculated that interpersonal comparisons could be performed using representative individual response ratio values as an indicator of the treatment effects of oral appliances.

DOI： 10.11242/dentalradiology.56.64

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Language：Japanese   Publisher：(NPO)日本歯科放射線学会  

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Language：Japanese   Publisher：(NPO)日本歯科放射線学会  

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Language：Japanese   Publisher：新潟歯学会  

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Language：Japanese   Publisher：(NPO)日本口腔科学会  

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Language：Japanese   Publisher：(NPO)日本顎変形症学会  

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Event date： 2021.5

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