Faculty Profiles - YOKOYAMA Akihito

Papers - YOKOYAMA Akihito

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Effects of Low-intensity Pulsed Ultrasound on Bone Formation with Gelatin Hydrogel Containing Bone Morphogenetic Protein-2 Reviewed

Yamaji Kozo, Yokoyama Akihito, Sugaya Tsutomu, Matsuzaki Kumiko, Takahashi Kei, Shinno Yasuo. Ohara, Naoko, Suzuki Shigeru

Journal of Oral Tissue Engineering 22 ( 2 ) 2024.12

Effects of BMP-2 on bone response using gelatin hydrogel in estrogen-deficient rats Reviewed

Yamaji K, Yokoyama A, Matsuzaki K, Sugaya T, Shimada Y, Ohara N, Yoshiyama M

Journal of Oral Tissue Engineering 20 ( 2 ) 41 - 46 2022.12

Effect of decontamination materials on bond strength of saliva-contaminated CAD/CAM resin block and dentin. Reviewed

Kei Takahashi, Tomohiro Yoshiyama, Akihito Yokoyama, Yasushi Shimada, Masahiro Yoshiyama

Dental materials journal 2022.4

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

The aim of this study was to evaluate the effect of decontamination agents against saliva contamination on the bonding of computer-aided design/computer-aided manufacturing (CAD/CAM) resin block. Three commercially available decontamination agents were used in this study. The samples were subjected to microtensile bond strength test. A saliva protein staining test was performed by the pigment binding method to investigate the effect of removing saliva protein. All the decontamination agents could significantly restore the bond strength from the saliva contamination, and KATANA Cleaner showed no significant difference with the control. From the results of the saliva protein staining test, KATANA Cleaner showed higher removal effect of saliva protein for CAD/CAM resin block surface than the other materials due to the surface active effect of MDP salt. It was suggested that cleaners containing MDP salt were more effective in removing artificial saliva contamination than cleaners containing other ingredients for CAD/CAM resin blocks.

DOI： 10.4012/dmj.2021-268

PubMed

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Effect of gelatin hydrogel containing BMP-2 on bone formation in aged rats Reviewed

Kozo YAMAJI, Akihito YOKOYAMA, Kumiko MATSUZAKI, Naoko OHARA, Tsutomu SUGAYA, Masahiro YOSHIYAMA

Journal of Oral Tissue Engineering 19 ( 1 ) 10 - 14 2021.9

漂白歯面変化のSS-OCT評価 Reviewed

神農泰生, 島田康史, 松﨑久美子, 横山章人, SADR Alireza, 角保徳, 田上順次, 𠮷山昌宏

日本歯科保存学雑誌 64 ( 4 ) 265 - 270 2021.8

新規汚染除去材による処理が唾液汚染されたCAD/CAM冠用ハイブリッドレジンブロックの象牙質接着強さに及ぼす影響 Reviewed

高橋圭, 𠮷山知宏, 横山章人, 島田康史, 𠮷山昌宏

日本歯科保存学雑誌 63 ( 6 ) 519 - 526 2020.12

Color Matching Evaluation Using the Visual Analog Scale Reviewed

Serina ONO, Masahiro YOSHIYAMA, Naoko OHARA, Kumiko MATSUZAKI, Kazuhiko SHIBUYA, Akihito YOKOYAMA, Kei TAKAHASHI, Yasuo SHINNO, Kozo YAMAJI, Yasushi SHIMADA

The Japanese Journal of Conservative Dentistry 63 ( 1 ) 30 - 37 2020.2

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japanese Society of Conservative Dentistry

Purpose: Recently, the application of composite resin restorations has expanded. Although chromatic studies of composite resins have progressed, color differences measured by colorimeters and visual color evaluation do not always match. The aim of this study was to establish a method of evaluating the visual color of composite resins by using the visual analog scale (VAS), which evaluates subjective data as a continuous variable, and to examine its validity. Method: One structural color composite resin (experimental resin : ECM-001) and three commercial composite resins of shade A3 were used in this study. Class Ⅴ and class Ⅲ cavities were prepared in artificial maxillary central incisors of four shades (A1, A2, A3, and A3.5) and each composite resin was filled and its color matching was evaluated on a black-and-white background using VAS. The correlation between VAS value and visual evaluation was analyzed. The color matching of teeth and composite resin were statistically analyzed using one-way analysis of variance and Tukey's HSD test (p<0.05). Background differences in the same sample were analyzed by the t-test (p<0.05). Results: In the Class Ⅴ restoration, ECM-001 showed better color matching than other composite resins. In the Class Ⅲ restoration, ECM-001 showed excellent color matching with a wide range of teeth shades on the white background. The VAS values of the other composite resins were higher on the black background than on the white background. However, the VAS value of ECM-001 on the black background tended to decrease. Because the evaluation of VAS color matching by evaluators showed the same tendency, the VAS value reflects information that can be recognized by visual observation. It is suggested that the evaluation of VAS value correlates with visual evaluation. Conclusion: It is suggested that the evaluation of color matching of composite resin restorations using VAS is useful for structural color composite resins, providing a new method of visually evaluating composite resin restorations.

DOI： 10.11471/shikahozon.63.30

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Effects of Direct Pulp Capping on Hard Tissue Formation by Using Alginate Gel Containing Reviewed

Akihito YOKOYAMA, Kozo YAMAJI, Naoko OHARA, Kumiko MATSUZAKI, Yasushi SHIMADA, Masahiro YOSHIYAMA

Journal of Oral Tissue Engineering 17 ( 2 ) 53 - 58 2019.12

透明根管模型歯における根管充填の評価法に関する検討

松﨑久美子, 大原直子, 澁谷和彦, 横山章人, 岡田俊輔, 村上純, 久富美紀, 浅海淳一, 吉山昌宏

岡山歯学会雑誌 38 ( 1 ) 11 - 18 2019.6

Effects of Transforming Growth Factor-β1 and Bone Morphogenetic Protein-2 on Bone Formation using a Bioabsorbable Scaffold at Palatal Sites in Rats Reviewed

Kozo YAMAJI, Akihito YOKOYAMA, Yasushi SHIMADA, Tsutomu SUGAYA, Naoko OHARA, Kumiko MATSUZAKI, Eriko NISHIYAMA, Masahiro YOSHIYAMA

Journal of Oral Tissue Engineering 16 ( 2 ) 74 - 79 2018.12

コンポジットレジン充填時における重合前の汚染による影響

横山章人

岡山歯学会雑誌 36 ( 1 ) 1 - 9 2017.6

Language：Japanese Publishing type：Doctoral thesis Publisher：岡山歯学会

コンポジットレジン充填操作時の重合前における血液等の汚染が、重合後のコンポジットレジンの接着強さや機械的強度に及ぼす影響について検討した。光重合型コンポジットレジンはクリアフィルマジェスティES-2を、歯面処理材はクリアフィルメガポンドFAを用いた。汚染物質には精製水と血液を用いた。微小引張り接着試験用試料の作製、微小引張り接着強さの測定、破断面形態の観察、ヌープ硬さ測定用試料の作製、汚染表面のヌープ硬さの測定、汚染表面の形態観察を行った。検討の結果、コンポジットレジン填塞後、未重合での水または血液による汚染は歯とコンポジットレジンの接着に影響を及ぼさなかった。一方、未重合レジンの血液汚染によりコンポジットレジン硬化後の表面硬さは明らかに低下したが、光照射時間の延長により硬さが改善した。重合前の汚染に対する対策法として光照射時間の延長が有効であることが示唆された。

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象牙質知覚過敏抑制材がセルフエッチング接着システムの接着性に及ぼす影響 Reviewed

松崎(田中, 久美子, 大原直子, 澁谷和彦, 小野瀬里奈, 横山章人, 山路公造, 吉山昌宏, 吉山昌宏

日本歯科保存学雑誌 60 ( 1 ) 22‐31(J‐STAGE) - 31 2017.2

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：(NPO)日本歯科保存学会

目的:象牙質知覚過敏抑制材の使用がコンポジットレジン修復に及ぼす影響を検討することを目的とし,象牙細管開口モデルに対して知覚過敏抑制材を塗布し,セルフエッチング接着システムの接着性の評価を行った.材料と方法:ヒト抜去小臼歯を用いて作製した象牙細管開口モデルに対して,3種の象牙質知覚過敏抑制材(MSコートONE,Fバニッシュ,ナノシール)を塗布し,表面性状を形態学的に評価した.また,知覚過敏抑制材を塗布し,7日間37℃水中保管後にクリアフィルメガボンドFAを用いて歯面処理を行った被着面を形態学的に検討した.さらに,コンポジットレジンを築盛して作製した接着試料体に対して微小引張接着試験を行い,接着強さを比較・検討した.結果:3種の象牙質知覚過敏抑制材を塗布した象牙細管開口モデル表面においては,いずれも知覚過敏抑制効果を表す形態学的特徴を示し,接着システムのプライミング効果に違いを認めたものの,接着強さは象牙細管開口モデル群ならびに3種の象牙質知覚過敏抑制材塗布群の間に有意差を認めなかった(p>0.05).結論:象牙細管開口モデルに対して本研究で使用した3種の象牙質知覚過敏抑制材は,その後に使用した接着システムの接着強さに影響を及ぼさないことが示された.(著者抄録)

DOI： 10.11471/shikahozon.60.22

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J-GLOBAL

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加齢が低強度パルス超音波照射を用いたBMP-2誘導性骨形成に及ぼす影響(Effects of Aging on Bone Formation Induced by BMP-2 using Low-intensity Pulsed Ultrasound) Reviewed

Yamaji Kozo, Yokoyama Akihito, Matsuzaki Kumiko, Ohara Naoko, Nishiyama Eriko, Sugaya Tsutomu, Yoshiyama Masahiro

Journal of Oral Tissue Engineering 14 ( 1 ) 65 - 69 2016.9

Language：English Publishing type：Research paper (scientific journal) Publisher：日本再生歯科医学会

加齢が骨形成に及ぼす影響を評価するため、12週齢(若齢群)と70週齢(老齢群)の雄性ラットを用いて低強度パルス超音波照射による骨形成蛋白質-2(BMP-2)誘発性骨形成を評価した。ラットの口蓋部骨膜下を3部位に分け、各部位をBMP-2移植(BMP群)、BMP-2移植3日後に低強度パルス超音波照射(超音波群)、および無処置(対照群)とした。移植3週後の新生骨の厚さ(TNB)を若齢群と老齢群、ならびに両群のBMP群、超音波群、対照群の間で比較した。その結果、TNBは若齢群と老齢群のいずれでも対照群より有意に大きく、若齢群のBMP群と超音波群のTNBは対応する老齢群のTNBより有意に大きかった。また、超音波群では新生骨が本来の骨にほぼ一体化していた。以上より、低強度パルス超音波照射は老齢ラットであってもBMP-2誘導性の骨形成を促進するが、その骨用量は加齢に伴って減少すると考えられた。

DOI： 10.11223/jarde.14.65

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ヒト脂肪組織由来幹細胞における多分化能と分化全能性の活性化の研究(Study of Pluripotency and Activation of Totipotency in Human Adipose-derived Stem Cells) Reviewed

Izawa Shunji, Yamaji Kozo, Yokoyama Akihito, Matsuzaki Kumiko, Ohara Naoko, Yoshiyama Masahiro

Journal of Oral Tissue Engineering 13 ( 3 ) 131 - 135 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：日本再生歯科医学会

ヒト脂肪組織由来幹細胞(hASCs)を用い、分化全能性としてTNF-α、エナメルマトリックスタンパク質Emd-GeLの主成分であるアメロゲニンを分化因子として、再生医療における多分化能および分化全能性アクチベーターとしての可能性について検討した。象牙芽細胞のマーカーとしては、Limホメオボックス蛋白質(Lhx)6、骨γ-カルボキシグルタミン酸含有タンパク質(BGLAP)を用いて、リアルタイムPCR法により観察を行った。その結果、アメロゲニンとTNF-αを含む培地で1週間培養したhASCsにおけるLhx6 mRNA発現は、他の培地に比べ有意に高発現を認め、BGLAP mRNA発現においてもTNF-α(+)培地で、他群よりも有意な高発現が認められた。以上の結果から、TNF-αは、hMSCやhASCのような組織由来幹細胞における分化能に必須なアクチベーターの一つと考えられた。

DOI： 10.11223/jarde.13.131

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Effects of Low-intensity Pulsed Ultrasound on Bone Formation Induced by Recombinant Human BMP-2 in Adult Rats Reviewed

YAMAJI Kozo, SUGAYA Tsutomu, KAWANAMI Masamitsu, YOSHIYAMA Masahiro, SHIODE Shintaro, ODAJIMA Tomoomi, NISHITANI Yoshihiro, IZAWA Shunji, TANAKA Kumiko, OHARA Naoko, NISHIMURA Maiko, YOKOYAMA Akihito

The Japanese Journal of Conservative Dentistry 56 ( 4 ) 318 - 324 2013.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：特定非営利活動法人日本歯科保存学会

Purpose: The purpose of this study was to evaluate the effects of low-intensity pulsed ultrasound (LIPUS) on bone formation induced by polylactate-polyglycolate-copolymer/gelatin sponge complexes (PGS) containing recombinant human bone morphogenetic protein-2 (rhBMP-2) at palatal subperiosteal sites (n=24) in 15-week-old male Wistar rats. Methods: RhBMP-2/PGS (1.0 μg/μl) was implanted into the palatal subperiosteal site and treated with LIPUS (1.0 MHz, 240 mW, 5 min) every 3 days (LI-BMP group) or without LIPUS (BMP group). In addition, rhBMP-2/PGS (1.0 μg/μl) was not implanted and rats were treated with LIPUS (LI group) or were not treated with LIPUS (Cont group). Animals were euthanized 3 weeks after surgery. Results: Thickness of new bone in LI-BMP and BMP groups was significantly higher when compared with LI and Cont groups (p<0.05). There were no significant differences in thickness of new bone between LI-BMP and BMP groups (p>0.05). Newly formed bone in the BMP group was continuous with the original bone. On the other hand, newly formed bone was largely integrated with the original bone in the LI-BMP group. Conclusion: These results suggest that LIPUS has the ability to enhance maturation of bone induced by rhBMP-2 in the case of palatal subperiosteal implantation in adult rats.

DOI： 10.11471/shikahozon.56.318

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J-GLOBAL

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Papers - YOKOYAMA Akihito