Miyashita, Hidetaka



School of Medicine, Department of Dentistry and Oral Surgery (Shinanomachi)


Assistant Professor/Senior Assistant Professor


Papers 【 Display / hide

  • Development of a microsurgery-assisted robot for high-precision thread traction and tension control, and confirmation of its applicability

    Hangai S., Nozaki T., Soma T., Miyashita H., Asoda S., Yazawa M., Sato K., Kawana H., Ohnishi K., Kobayashi E.

    International Journal of Medical Robotics and Computer Assisted Surgery (International Journal of Medical Robotics and Computer Assisted Surgery)  17 ( 2 )  2021.04

    ISSN  14785951

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    Background: Microsurgery requires high skills for suturing using fragile threads, often within narrow surgical fields. Precise tension is required for good healing and to avoid the risk of thread breakage. Methods: To meet the demands, we developed a novel assist robot utilizing high-precision sensorless haptic technology. The robot adopts a cable-driven mechanism to maintain a distance from the surgical area and enhances compatibility with surgical equipment such as microscopes. The robot performance was verified through in vitro and in vivo experiments using a rat model. Results: The realization of precise tension control was confirmed in both experiments. In particular, in the in vivo experiments, the developed robot succeeded to produce a knot with an accurate tension of 0.66% error. Conclusions: The developed robot can realize to control traction force precisely. This technology might open up the window for a full assist robot for microsurgery with haptic feeling.

  • Low-grade osteosarcoma is predominant in gnathic osteosarcomas: A report of seven cases of osteosarcoma of the jaw

    Sasaki A., Miyashita H., Kawaida M., Kameyama K.

    Clinical and Experimental Dental Research (Clinical and Experimental Dental Research)   2021

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    Objective: Primary osteosarcoma of the jaw bones is very rare, and histological features of gnathic osteosarcoma remain obscure. The purpose of this study was to describe the clinicopathological features of gnathic osteosarcoma. Materials and methods: Seven cases of gnathic osteosarcoma from Japan diagnosed during the period between 2000 and 2016 were examined retrospectively. The histology of the surgical pathology materials was reviewed by two pathologists. Clinical information was obtained from the hospital's information system. Results: Of the seven cases, two patients had secondary osteosarcomas. As for the five cases of primary osteosarcoma, their ages ranged from 26 to 58 years (mean: 36.2, median: 28). Histologically, three cases were fibrotic tumors composed of spindle-shaped cells with mild to moderate nuclear atypia and the collagenous stroma accompanied by woven bones or mature lamellar-like bones. Two cases had cartilage formation. MDM2 and CDK4 expression was observed in two out of three cases on immunostaining. The histopathology of these three cases was regarded as the counterpart of low-grade osteosarcomas, namely, parosteal osteosarcoma and low-grade central osteosarcoma, arising in long bones. Conclusions: The surprisingly high incidence (60%, 3/5 cases) of low-grade osteosarcoma explains the reason why gnathic osteosarcomas present a more favorable prognosis than osteosarcomas arising in long bones. Furthermore, it provides insight into the tumorigenesis mechanism of low-grade osteosarcomas arising in the jaw and other sites.

  • Clear cell carcinoma in the retromolar area: A case report

    Yasui Y., Asoda S., Soma T., Miyashita H., Hasegawa T., Ouchi T., Karube T., Yasui T., Onizawa K., Nakagawa T., Kawana H.

    Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology (Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology)  32 ( 6 ) 507 - 513 2020.11

    ISSN  22125558

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    Clear cell carcinoma (CCC) is a malignant neoplasm of epithelial origin classified in the 2017 World Health Organization (WHO) classification as a low-grade salivary gland tumor consisting of glycogen-rich clear cytoplasm. We report a case of a 34-year-old woman presented in our department following the complaint of a mass in her right retromolar area. The tumor measured 10-mm in diameter and was elastic and hard mass. Spontaneous pain or tenderness and desensitization of the tongue were not observed. Marginal resection of the mandible was performed under general anesthesia. The lesion was located in the minor salivary gland that is mainly composed of mucus glands and had a relatively clearly defined circular shape. However, there was no film fabrication in the surrounding resions. Additionally, atypical cells comprising a clear cytoplasm and irregularly shaped pyknotic nuclei were growing in sheet form or island form, and markedly hyalinized fascicles were observed between the alveolar walls of the atypical cells. Immunohistochemical stains revealed these tumor cells to be positive for epithelial cell markers but negative for myoepithelial ones. Considering the above findings, the tumor was diagnosed as CCC. The patient is currently free from disease 37 months after surgery.

  • Clinical value of 3D SPECT/CT imaging for assessing jaw bone invasion in oral cancer patients

    Miyashita H., Nakahara T., Asoda S., Kameyama K., Kawaida M., Enomoto R., Shiba H., Jinzaki M., Kawana H., Nakagawa T.

    Journal of Cranio-Maxillofacial Surgery (Journal of Cranio-Maxillofacial Surgery)  47 ( 7 ) 1139 - 1146 2019.07

    ISSN  10105182

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    © 2019 European Association for Cranio-Maxillo-Facial Surgery Purpose: This study compared the diagnostic accuracy of jaw bone invasion (JBI) of oral cancer observed with three-dimensional (3D) SPECT/CT, CT, and MRI, and evaluated the clinical advantages of 3D SPECT/CT compared to conventional two-dimensional (2D) SPECT/CT. Materials and methods: From April 2014 to January 2018, consecutive 16 oral cancer patients with suspected JBI, who had preoperatively undergone the imaging tests, were retrospectively enrolled. The likelihood of JBI was independently scored by a radiologist and oral surgeon. Using 2D or 3D SPECT/CT images, 20 oral surgeons delineated virtual surgical areas on 3D-printed jaws for 3 cases in which the extent of JBI was fully pathologically confirmed. The surgeons completed questionnaires regarding surgical planning and explanations for patients using Likert scales. Results: JBI was found in 9 patients including 5 (56%) with initial bone invasion. 3D SPECT/CT showed very high negative predictive value (100%) and inter-observer agreement (kappa = 0.917). 3D SPECT/CT was more sensitive than CT and MRI when inconclusive findings for JBI were considered negative. Compared to 2D SPECT/CT, 3D SPECT/CT had greater clinical advantages such as surgical planning and explanation to patients (p < 0.005). Conclusion: 3D SPECT/CT is useful not only for detecting JBI but also for surgical planning.

  • Acute odontogenic infection combined with crowned dens syndrome: A case report

    Soma T., Asoda S., Kimura M., Munakata K., Miyashita H., Nakagawa T., Kawana H.

    Journal of Medical Case Reports (Journal of Medical Case Reports)  13 ( 1 )  2019.05

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    © 2019 The Author(s). Background: Calcium pyrophosphate dihydrate crystal deposition disease is a condition in which calcium pyrophosphate dihydrate crystal is deposited in joint cartilage and ligaments. Calcium pyrophosphate dihydrate crystal deposition disease that involves calcification around the odontoid process of the second cervical vertebra is called crowned dens syndrome. Crowned dens syndrome is accompanied by fever in addition to acute and intense neck, posterior head, and temporal pain; thus, distinguishing crowned dens syndrome may be difficult in the presence of odontogenic infection. To the best of our knowledge, this is the first report describing a patient with crowned dens syndrome with coexisting odontogenic infection. Case presentation: A 75-year-old Japanese woman was examined in the Emergency Department of this hospital due to a chief complaint of worsened buccal swelling on the left side. An odontogenic infection was considered, and she underwent her first examination. She presented with a body temperature of 37.4 °C, marked swelling and tenderness of her left lower eyelid through to her left cheek, and pain on the left temporal area. Blood tests revealed a leukocyte count of 6700/μL and a C-reactive protein level of 7.15 mg/dL. There was swelling and pain around the gingiva and acute purulent apical periodontitis of left maxillary second premolar. Cellulitis of the left cheek was diagnosed. After performing drainage of the pus, antibiotic treatment was initiated. Although her clinical symptoms improved, blood tests on day 9 of hospitalization revealed a leukocyte count of 6500/μL and a C-reactive protein level of 25.62 mg/dL, which were indicative of worsening symptoms. Computed tomography was performed to evaluate remote infection and images revealed a calcification around the odontoid process of her second cervical vertebra. When she was referred to the Orthopedic Surgery Department, pseudogout of the cervical spine was diagnosed. Subsequently, oral acetaminophen was initiated, and both her leukocyte count and C-reactive protein improved markedly. Conclusions: In the presence of persistent fever and abnormally high leukocyte and C-reactive protein indicative of an inflammatory reaction, coexistence of pseudogout should be considered. In particular, when symptoms of temporal pain are present, the possibility of pseudogout of the cervical spine must be considered in the differential diagnosis.

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Research Projects of Competitive Funds, etc. 【 Display / hide

  • 広範囲顎骨欠損に対するメカノバイオロジー最適化スキャフォールドの開発


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 宮下 英高, Grant-in-Aid for Early-Career Scientists , Principal Investigator


Courses Taught 【 Display / hide