著者

Kyozo Sasaki Mitsuru Motoyoshi Eri Horinuki Yoshinori Arai Noriyoshi Shimizu

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.3, pp.415-422, 2016 (Released:2016-09-25)

参考文献数

31

被引用文献数

4

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This study examined the effects of a bite-jumping appliance combined with low-intensity pulsed ultrasound (LIPUS) stimulation on the mandibular condyle of growing rats using micro CT (mCT) and histological examinations. Twelve Wistar rats were divided into three groups of four individuals each: Group 1 was an untreated control group, Group 2 received bite-jumping appliances, and Group 3 received bite-jumping appliances and LIPUS stimulation (15 min/day, 2 weeks) to the temporomandibular region. We measured the length and three-dimensional bone volume of each rat’s mandibular condyle using mCT. The condylar cartilage was observed after the rats had been sacrificed. There was no significant difference in condylar sagittal width among the groups. The bite-jumping appliance combined with LIPUS stimulation increased the condylar major axis, mandibular sagittal length and condylar bone volume to a greater degree than use of the bite-jumping appliance alone. Histological examination demonstrated hypertrophy of the condylar cartilage layers, the fibrous layer and hypertrophic cell layer of the rats treated with bite-jumping appliances combined with LIPUS stimulation in comparison to rats treated with bite-jumping appliances alone. (J Oral Sci 58, 415-422, 2016)

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

Motohiro Ito Yusuke Hayashi 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

vol.63, no.1, pp.87-91, 2021 (Released:2020-12-23)

参考文献数

23

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Purpose: The spatial resolution of cone-beam computed tomography (CBCT) in small fields of view (FOVs) is important for clinical applications. However, it is difficult to measure spatial resolution reliably due to error factors such as noise. The aim of this study was to obtain a modulation transfer function (MTF) more accurately.Methods: A CBCT apparatus was used with small FOV. An aluminum pipe slightly tilted at an inclination ratio of 77/3 (25.7) was used as the measurement phantom. The MTF was calculated from the edge image of the phantom. The actual oversampling ratio was determined by regression analysis. The experiment was repeated 16 times and the edge-spread function (ESF) was approximated by the least-square method. Furthermore, a low-pass filter (LPF) was applied to eliminate the component at frequencies above the Nyquist frequency. Finally, the MTF was calculated from the pre-processed ESF.Results: Results showed that pre-processing reduced the noise of the ESF. The MTFs at frequencies of 1.0 and 2.0 LP/mm were 0.59 and 0.18, respectively, in air and 0.52 and 0.16, respectively, in water.Conclusion: The repeating-edge oversampling method combined with ESF pre-processing improved the accuracy of the MTF under clinically relevant conditions with a phantom.

著者

Ryosuke Koshi Kunihito Matsumoto Yusuke Imanishi Takayuki Kawato Shuichi Sato Shigeki Shimba 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.63, no.1, pp.83-86, 2021 (Released:2020-12-23)

参考文献数

33

被引用文献数

6

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Purpose: Circadian rhythm is associated with the pathogenesis of systemic disease and bone mineral metabolism. This study aimed to radiographically evaluate morphological characteristics of the interalveolar septum in circadian rhythm deficient animals.Methods: Heads of 10 brain and muscle arnt-like protein-1 (BMAL1)-knockout (KO) mice and 10 wild-type mice sacrificed at 36 weeks were imaged using micro-computed tomography. The mean depth from the cementoenamel junction to the alveolar ridge (virtual bone sounding: VBS) of the interalveolar septum between the first and second molars, and the bone mineral density (BMD) of the interalveolar septum and the mandibular inferior cortex region were calculated. Tooth diameter was also measured.Results: The VBS of the interalveolar septum in the BMAL1-KO mice was significantly deeper than that in wild-type mice. The BMD in the BMAL1-KO mice was significantly lower than in the wild-type mice in both regions. No significant difference was observed in tooth diameter between BMAL1-KO and wild-type mice.Conclusion: These results suggest that low BMD in the interalveolar septum accelerates bone resorption in the interalveolar septum in BMAL1-KO mice.

著者

Yusuke Hayashi Motohiro Ito Yusuke Imanishi Kenichiro Watanabe 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.19-0307, (Released:2020-06-10)

参考文献数

24

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The present study used an aluminum phantom to calculate accurate vertical magnification values around the mental foramen on panoramic radiography (PR) and compared corrected PR (Cor-PR) thickness measurements of the aluminum phantom and mandibular cortical width (MCW) of the human head with cone-beam computed tomography (CBCT) measurements at two fields of view (FOVs). The calculated vertical magnification value for PR around the mental foramen was 1.37. Measurements of the aluminum phantom significantly differed between Cor-PR and CBCT with an FOV of 100 mm and between CBCT with FOVs of 40 and 100 mm; however, MCW measurements did not significantly differ among the three methods. There was a very strong correlation between Cor-PR and CBCT with an FOV of 40 mm and between CBCT with FOVs of 40 mm and 100 mm, and intraobserver and interobserver agreement was good-to-excellent for all methods. These results suggest that Cor-PR and CBCT with small and large FOVs are acceptable for measuring MCW.

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

Atsushi Tateno Masatake Asano Daisuke Akita Taku Toriumi Niina Tsurumachi-Iwasaki Tomohiko Kazama Yoshinori Arai Taro Matsumoto Koichiro Kano Masaki Honda

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

pp.18-0458, (Released:2019-10-21)

参考文献数

45

被引用文献数

13

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Tissue engineering is a promising approach to supplement existing treatment strategies for craniofacial bone regeneration. In this study, a type I collagen scaffold made from a recombinant peptide (RCP) with an Arg-Gly-Asp motif was developed, and its effect on regeneration in critical-size mandibular bone defects was evaluated. Additionally, the combined effect of the scaffold and lipid-free dedifferentiated fat (DFAT) cells was assessed. Briefly, DFAT cells were separated from mature adipocytes by using a ceiling culture technique based on buoyancy. A 3 cm × 4 cm critical-size bone defect was created in the rat mandible, and regeneration was evaluated by using RCP with DFAT cells. Then, cultured DFAT cells and adipose-derived stem cells (ASCs) were seeded onto RCP scaffolds (DFAT/RCP and ASC/RCP) and implanted into the bone defects. Micro-computed tomography imaging at 8 weeks after implantation showed significantly greater bone regeneration in the DFAT/RCP group than in the ASC/RCP and RCP-alone groups. Similarly, histological analysis showed significantly greater bone width in the DFAT/RCP group than in the ASC/RCP and RCP-alone groups. These findings suggest that DFAT/RCP is effective for bone formation in critical-size bone defects and that DFAT cells are a promising source for bone regeneration.

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

Hidekazu Nagashima Masamichi Shinoda Kuniya Honda Noriaki Kamio Akira Hasuike Naoyuki Sugano Yoshinori Arai Shuichi Sato Koichi Iwata

出版者

日本大学歯学部

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

pp.16-0830, (Released:2017-10-31)

参考文献数

45

被引用文献数

13

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Periodontitis caused by bacterial infection gradually progresses accompanied by periodontal tissue destruction. As a result, teeth lose their supporting structures, and this leads to tooth exfoliation. CXC-chemokine receptor 4 (CXCR4) is known to be expressed in lymphocytes, fibroblasts and osteoclasts in periodontal tissues, suggesting that periodontal CXCR4 signaling contributes to alveolar bone resorption in the milieu of periodontitis. However, the role of CXCR4 signaling in the pathogenesis of periodontitis has remained unknown. We established a mouse model of periodontitis by inoculation of Porphyromonas gingivalis (P.g.) into a silk ligature placed around the maxillary molar. Although there was no significant difference in the mechanical sensitivity in the periodontal tissue between P.g. treatment and sham treatment during the experimental period, mechanical allodynia in the periodontal tissue was induced after gingival injection of complete Freund’s adjuvant compared with that resulting from sham and P.g. treatment alone. Moreover, CXCR4 neutralization in the periodontal tissue following P.g. treatment enhanced periodontal inflammatory cell infiltration and depressed alveolar bone resorption. These findings suggest that periodontal CXCR4 signaling in several cell types in P.g.-induced periodontal inflammation depresses alveolar bone resorption in periodontitis. CXCR4 signaling might be a target for therapeutic intervention to prevent alveolar bone resorption in periodontitis.