著者

Masao Kato Shoichi Asakura Hideaki Kimoto Tatsuhiko Sasaki Ko Dezawa Toshihiko Amemiya Kunihito Matsumoto Yoshinori Arai

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

pp.23-0298, (Released:2023-11-30)

参考文献数

24

被引用文献数

1

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Purpose: To evaluate the image quality of vertical dual-exposure panoramic radiography (PR), which merges two PR images taken at different focus heights to reduce ghost images of cervical vertebrae (CV) and intervertebral spaces (IVS) in the incisor region.Methods: PR images of an aluminum block, a CV phantom and a human head phantom were taken at 0 mm and merged with and subtracted from PR images taken at other heights (0, 5, 10, 15, and 20 mm) to create new images, e.g., Merg0 + 15 mm and Sub0 − 10 mm. The subtracted images were analyzed subjectively according to the uniformity on the line profile. Merged images were evaluated subjectively by six raters to determine the influence of the ghost images.Results: Objective evaluation revealed a positional shift in the ghost images according to the height of the focus for both phantoms. In the subjective evaluation, the normal PR (Merg0 + 0 mm) showed the worst score, indicating strong influence of CV and IVS ghost images.Conclusion: The vertical dual-exposure PR method, which merges PR images taken at the normal position and a higher X-ray focus, can reduce CV and IVS ghost images in the incisor region.

著者

Takahito Sekiguchi Masao Kato Hideaki Kimoto Toshihiko Amemiya Ko Dezawa Yusuke Imanishi Kunihito Matsumoto Yoshinori Arai

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.65, no.1, pp.40-43, 2023 (Released:2023-01-11)

参考文献数

13

被引用文献数

2

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Purpose: The dual imaging plate (DIP) method, which synthesizes intraoral radiographs from a front imaging plate (FIP) and a back imaging plate (BIP), produces adequate image quality and allows the radiation dose to be reduced. However, there are slight errors in superimposition and alignment between the FIP and BIP. The aim of this study was to establish positional correction in the DIP method and evaluate the effect.Methods: Six sets of two imaging plates were used for imaging a mesh plate and a porcine mandible phantom. Subtraction images between FIP and BIP images were synthesized in four steps: correcting horizontal and vertical direction, rotation, enlargement ratio, and enlargement ratio into 12 blocks. Variance of the pixel value on the subtraction images at each step was compared to evaluate the alignment of FIP and BIP images.Results: The variance of the pixel values in the subtraction images was gradually and significantly decreased by each step of image processing (P < 0.01), indicating that the degree of alignment of FIP and BIP images improved during the image processing.Conclusion: The present study revealed that it is possible to synthesize more precise DIP images using an additional four-step image processing technique.

著者

Kenichiro Watanabe Yusuke Imanishi Masao Kato Hideaki Kimoto Takahito Sekiguchi Toshihiko Amemiya Ko Dezawa Kunihito Matsumoto Yoshinori Arai Kazuya Honda

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

pp.21-0454, (Released:2021-12-27)

参考文献数

23

被引用文献数

3

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Purpose: This study evaluated the contrast-to-noise ratio (CNR), spatial resolution, and subjective quality of dual imaging plates (DIP) intraoral radiography.Methods: The DIP and conventional single IP (CSIP) methods both used YCR DT-1 imaging plates (Yoshida Co.). The DIP, comprising a front IP (FIP) and back IP (BIP), was constructed. DIP images were synthesized from the FIP and BIP images. An aluminum step phantom was used to measure the CNR. A line pair gauge was used to measure the spatial imaging resolution. A phantom comprising a porcine mandible embedded in acrylic resin was used for subjective evaluation.Results: The CNR of the DIP image was 32% higher than that of the FIP image. The spatial resolution achieved using the FIP, DIP, and CSIP was highly comparable except above 4 line pairs/mm, where that of the CSIP was highest. In subjective evaluation, the noise in the DIP images was significantly lower than in those obtained using the FIP and CSIP.Conclusion: The CNR of the DIP was higher than that of the FIP. The decrease in spatial resolution of the DIP was limited. The subjective image quality of the DIP was higher than that of the FIP.

著者

Kunihito Matsumoto Toshihiko Amemiya Motohiro Ito Yusuke Hayashi Kenichiro Watanabe Ko Dezawa Yoshinori Arai Kazuya Honda

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.62, no.1, pp.62-66, 2020 (Released:2020-01-29)

参考文献数

35

被引用文献数

2

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This study was performed to develop a new rat model of reduced masticatory activity in order to assess the effect of this reduction on the morphology of the temporomandibular joint (TMJ) over time. Female rats were used, and ovariectomy was performed to simulate aged/postmenopausal status. Twenty-four SD rats aged 6 weeks were divided into four groups: ovariectomy/sham procedure (Ov/S); ovariectomy/reduced masticatory activity (Ov/RMA); non-Ov/S (NO/S); and non-Ov/RMA (NO/RMA). The RMA procedure involved grinding down the edges of the upper and mandibular incisors by about 3 mm and supplying the rats with a powdered diet. The bilateral TMJ was examined by micro-computed tomography at 0, 1, 2, 4, 6, and 8 weeks after the start of RMA. Condylar width was greater in the NO/S group than in the Ov/S group after the 2nd week, showing that ovariectomy reduced the width of the condyle. After the 2nd week, significant differences in condylar width were apparent between the NO/S and NO/RMA groups, and between the Ov/S and Ov/RMA groups. This RMA procedure appeared to provide a good model of reduced masticatory activity. The present findings in female rats suggest that reduction of appropriate mastication activity in the growth period results in poor growth of the mandibular condyle and immediately induces atrophy of the mandibular condyle under conditions simulating aged/postmenopausal status.

著者

Shigenori Hirai Yusuke Hayashi Motohiro Ito Toshihiko Amemiya Ko Dezawa Yoshinori Arai Ken-ichiro Ejima Shigeki Shimba Kazuya Honda

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

pp.17-0390, (Released:2018-08-25)

参考文献数

19

被引用文献数

5

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Brain and muscle Arnt-like protein-1 (BMAL1) knockout mice exhibit accelerated aging, abnormal glucose metabolism, and impaired adipocyte differentiation, among other phenotypes, which are effects associated with the BMAL1 gene. No study has investigated temporal changes in the deformation of the mandibular condyle and the presence of calcification in areas surrounding the mandibular condyle. In a study of 12 C57/BL strain mice under inhalation anesthesia, we collected images of the mandibular condyle at 6 weeks after birth and then every 5 weeks from 10 to 25 weeks after birth. At 25 weeks, deformation of the mandibular condyle was seen in 8 of 12 joints in BMAL1 knockout mice and in 2 of 12 joints in wild-type mice. At 20 and 25 weeks, deformation in areas surrounding the mandibular condyle, which are known to undergo calcification, was seen in 2 of 12 joints in BMAL1 knockout mice and in 0 of 12 joints in wild-type mice. BMAL1 knockout mice exhibited premature aging of the mandibular condyle, which suggests that circadian rhythms affect mandibular condyle morphology.

著者

Kunihiko Sawada Toshihiko Amemiya Shigenori Hirai Yusuke Hayashi Toshihiro Suzuki Masahiko Honda Johnny Sisounthone Kunihito Matsumoto Kazuya Honda

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.60, no.1, pp.137-141, 2018 (Released:2018-03-24)

参考文献数

23

被引用文献数

5

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We compared the diagnostic reliability of 3.0-T magnetic resonance imaging (MRI) for detection of osseous abnormalities of the temporomandibular joint (TMJ) with that of the gold standard, cone-beam computed tomography (CBCT). Fifty-six TMJs were imaged with CBCT and MRI, and images of condyles and fossae were independently assessed for the presence of osseous abnormalities. The accuracy, sensitivity, and specificity of 3.0-T MRI were 0.88, 1.0, and 0.73, respectively, in condyle evaluation and 0.91, 0.75, and 0.95 in fossa evaluation. The McNemar test showed no significant difference (P > 0.05) between MRI and CBCT in the evaluation of osseous abnormalities in condyles and fossae. The present results indicate that 3.0-T MRI is equal to CBCT in the diagnostic evaluation of osseous abnormalities of the mandibular condyle.

著者

Masao Araki Shunsuke Namaki Toshihiko Amemiya Kunihito Matsumoto Kazuya Honda Yoshiyuki Yonehara Naoyuki Matsumoto Masatake Asano

出版者

日本大学歯学部

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.58, no.4, pp.533-537, 2016 (Released:2016-12-23)

参考文献数

32

被引用文献数

3

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The occurrence of ameloblastic fibro-odontoma (AFO) in the oral region is unusual and accounts for 1-3% of all odontogenic tumors. AFO presents mixed radiopaque patterns within the lesion with diverse findings; therefore, it is important to compare this tumor with other odontogenic tumors that radiographically present with calcified bodies. Herein, we observed the calcification patterns within the lesion in seven AFO cases (five males, two females; mean age, 8.3 years; age range, 4-13 years). Periapical and panoramic radiographs were obtained from all seven cases. Five cases underwent conventional computed tomography (CT) scanning, and one underwent cone beam CT. Classification of the calcifications primarily involved the following two characteristics on the X-rays: appearance and location of the lesions. All seven cases were located in the molar regions of the mandible in association with impacted teeth. The calcification patterns of these AFOs were mixed or inhomogeneous within the lesion with various findings, including complex odontoma-like calcifications. However, the patterns differed between panoramic radiography and CT in some cases. The radiolucent lesions in AFO demonstrated varying calcification patterns and were associated with impacted teeth on the CT images.(J Oral Sci 58, 533-537, 2016)