Researcher Profile and Settings

Master

Affiliation (Master)

• Faculty of Dental Medicine　Division of Dental Medicine　Department of Functional Science

Affiliation (Master)

• Faculty of Dental Medicine　Division of Dental Medicine　Department of Functional Science

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Profile and Settings

Degree

• PhD.DDs（Hokkaido University）

Profile and Settings

• Name (Japanese)

  Yawaka

• Name (Kana)

  Yasutaka

• Name

  200901011593929957

Achievement

Research Interests

• 小児歯科学   歯根吸収に関する組織学   Pediatric Dentistry   Histology of root resorption   

Research Areas

• Life sciences / Developmental dentistry
• Life sciences / Oral medicine

Research Experience

• 2003/04 - 2005/03 北海道大学病院歯科診療センター 咬合B（小児歯科専門）外来 講師
• 2000/04 - 2003/03 Hokkaido University Graduate School of Dental Medicine
• 1993/06 - 2000/03 北海度大学歯学部 小児歯科学講座 助手
• 1990/01 - 1993/05 Hokkaido University School of Dental Medicine
• 1986 - 1989 Hokkaido University School of Dental Medicine
• 1986 - 1989 Medical Staff

Committee Memberships

• 2006   Asian International Association of Dental Traumatology   Executive Director   Asian International Association of Dental Traumatology

Awards

• 2020/09 日本外傷歯学会 学会賞
   

  受賞者: 八若保孝

Published Papers

• 当大学病院小児・障害者歯科外来における2016年から5年間の新規来院患者の実態調査

  趙 継美, 高木 康多, 高橋 静香, 竹渕 塁, 中村 光一, 八若 保孝

  小児歯科学雑誌 (公社)日本小児歯科学会 61 (3) 110 - 116 0583-1199 2023/11 

  高次医療機関である北海道大学病院の小児・障害者歯科外来の実態とその時代に伴う変化について把握することを目的に当外来における2016年から5年間の新規来院患者の実態を調査し,以下の結論を得た。1.1年間の平均新規来院患者数は338名であり,年によって若干の差が認められた。男性が57.1%,女性が42.9%を占め,性差が認められた。2.初診時の年齢は4～7歳にピークを認めた。3.主訴はむし歯・歯痛が46.8%と最も多かった。4.新規来院患者の居住地域は札幌市内が74.1%を占めたが,隣接市町村や100km以上離れた地域からの患者も認められた。5.既往疾患を有する患者の割合は41.1%であった。疾患の内容としては精神・行動の障害を有する患者が最も多かった。6.行動変容法を含む通法通りの診療を行った患者は71.8%であり,それ以外は体動抑制や全身麻酔下での診療が必要であった。全身麻酔下での年間平均症例数は既報と比較して増加傾向であった。7.紹介患者は80.3%であり,既報と比較して割合が増加していた。歯科医院からの紹介が大多数であったが,医科や他の医療施設からの紹介も認められた。以上のことから,高次医療機関の小児・障害者歯科として,さまざまな症例に対応するための専門的な知識・技術を有すること,また,医科歯科連携の重要性の高まりなど,時代とともに変化していく医療体制や小児・障害者歯科のニーズに応じることの必要性が示唆された。(著者抄録)
• Incremental lines in human cellular cementum: A histological study.

  Shizuka Takahashi, Tsuneyuki Yamamoto, Tomomi Takahashi, Yasutaka Yawaka

  Journal of oral biosciences 65 (1) 55 - 61 2023/03 

  OBJECTIVES: Human cellular cementum has incremental lines that demarcate individual cementum lamellae. The structural and functional details of the lines remain poorly understood. This study was designed to examine human cellular cementum using light microscopy, scanning electron microscopy, and contact microradiography and to elucidate the ultrastructure of incremental lines and their significance in cellular cementogenesis. METHODS: Longitudinal paraffin and ground sections of human mandibular molars were prepared. Paraffin sections were stained with hematoxylin, or hematoxylin and eosin, or impregnated with silver. Hematoxylin-stained sections were observed via scanning electron microscopy using NaOH maceration. Silver-impregnated sections were further stained with hematoxylin. Hematoxylin-stained ground sections were examined using contact microradiography. RESULTS: The incremental lines were found to be collagen fibril-poor layers. The outer area of each cementum lamella consisted of highly mineralized fibrils involved in constructing an alternating lamellar structure, whereas the inner area consisted of irregularly arranged, less highly mineralized, fibrils. The incremental lines corresponded with the innermost sites of the inner area. CONCLUSIONS: Based on the obtained findings, we suggest that cellular cementogenesis progresses as follows. (1) Cementoblasts alternate between low-to high-activity states. (2) In the earliest low-activity stage, cementoblasts generate poorly mineralized, fibril-poor, incremental lines. (3) As cementoblasts recover activity, fibril-organization and mineralization advance in the cementum. (4) In the high-activity stage, cementoblasts reach full activity and construct the highly mineralized, alternating lamellar structure. (5) Cementoblasts revert back to the low-activity stage. (6) The above processes are repeated, thus, alternately generating the incremental lines and cementum lamellae.
• Impacted mandibular primary second molar: A case report

  Yasutaka Yawaka, Kyoko Shinoguchi, Makoto Fujii, Shohei Oshima

  Pediatric Dental Journal 32 (2) 123 - 128 2022/08 [Refereed][Not invited]
  
• A rare case of multiple brain abscesses caused by apical periodontitis of deciduous teeth in congenital heart disease: a case report.

  Shizuka Takahashi, Hisato Segoe, Takashi Kikuiri, Yuji Maruo, Tomonobu Sato, Yutaka Watanabe, Zhao Jimei, Yoshitaka Yoshimura, Misa Ishiyama, Atsuhito Takeda, Yasutaka Yawaka, Tetsuo Shirakawa

  BMC oral health 22 (1) 261 - 261 2022/06/28 [Refereed][Not invited]
   

  BACKGROUND: A brain abscess is a focal infection in which abscesses form in the brain. A brain abscess is a rare but fatal disease when rupture occurs into the ventricles. We report a case of multiple brain abscesses caused by a hematogenous infection from the apical periodontitis of deciduous teeth. CASE PRESENTATION: The patient was a 7-years and 8-months-old male with congenital heart disease. The patient sought medical attention due to fever and headache, for which he was started on three antibiotics with a diagnosis of multiple brain abscesses. Given that apical periodontitis of deciduous teeth was strongly suspected as the source of the brain abscess, the deciduous teeth were extracted. Immediately after deciduous teeth extraction, the patient's headache and neurological symptoms disappeared. CONCLUSIONS: After teeth extraction, a clear shrinkage of the brain abscess was observed, and the patient was discharged from the hospital.
• Adhesion in pediatric dentistry

  Yasutaka Yawaka

  日本歯科理工学会誌 41 (1) 52 - 57 2022 [Refereed][Invited]
  
• Occurrence of subcutaneous emphysema during a caries filling procedure: A case report

  Takashi Kikuiri, Kureha Saito, Airi Iida, Yoshitaka Yoshimura, Yasutaka Yawaka, Tetsuo Shirakawa

  Pediatric Dental Journal 2022 [Refereed][Not invited]
  
• Bone resorption improvement by conditioned medium of stem cells from human exfoliated deciduous teeth in ovariectomized mice.

  AYAKO MAEDA, TAKASHI KIKUIRI, YOSHITAKA YOSHIMURA, YASUTAKA YAWAKA, TETSUO SHIRAKAWA

  EXPERIMENTAL AND THERAPEUTIC MEDICINE 23 (4) 1792-0981 2022 [Refereed]
  
• N-acetylcysteine attenuates PGE2 and ROS production stimulated by 4-META/MMA-based resin in murine osteoblastic cells.

  Koichi Nakamura, Hajime Minamikawa, Shizuka Takahashi, Yoshitaka Yoshimura, Yasutaka Yawaka

  Dental materials journal 40 (3) 808 - 812 2021/05/29 

  This study examined the effects of N-acetylcysteine (NAC) on the inflammatory reactions of murine osteoblastic cells cultured on the 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate (4-META/MMA)-based resin. Superbond C&B (SB) was used as the 4-META/MMA-based resin and placed in a 48-well cell culture plate. The cells were cultured in αMEM (control) as well as on SB and SB in αMEM with NAC (SB+NAC). They were examined using the WST-1 proliferation assay, real-time PCR, enzyme-linked immunosorbent assay (ELISA), intracellular reactive oxygen species (ROS) measurements, and cellular glutathione (GSH) detection. COX-2 and IL-6 gene expressions were upregulated in SB; however, they were suppressed by NAC. Furthermore, PGE2 production in the culture medium was increased in SB, whereas NAC decreased the PGE2 production. NAC lowered the ROS level in the culture medium and significantly increased the intracellular GSH level. The present in vitro study demonstrated that NAC might be effective for dental material detoxification.
• Evaluation of maturation of bone and teeth during the early stage of school age and the relationship between chronological age, bone age, and dental age

  Mayuko Kato, Ayako Maeda, Mitsuhiko Nishimi, Kanji Iwadera, Nobuki Iwadera, Toshihiro Yoshihara, Yasutaka Yawaka

  日本小児歯科学雑誌 59 (2) 71 - 79 2021/05 [Refereed]
  
• National investigation on home visit dental treatment for children in Japan.

  Takai Rihito, Tamura Humiyo, Kikutani Takeshi, Ogata Kiyokazu, Oshima Shohei, Yawaka Yasutaka

  Disability and Oral Health 42 (1) 91 - 98 2021/02 [Refereed][Not invited]
  
• A survey of the state of new patients at the Clinical Department of Dentistry for Children and Disabled Persons of a University Dental Hospital over the past six years

  Ayako Maeda, Akina Hisada, Megumi Hoshino, Nobuki Iwadera, Risa Taneichi, Kouichi Nakamura, Chihiro Takasaki, Yasutaka Yawaka

  日本小児歯科学雑誌 58 (3) 149 - 156 2020/10 [Refereed]
  
• Effects of N-acetylcysteine on root resorption after tooth replantation

  Mitsuhiko Nishimi, Koichi Nakamura, Akina Hisada, Kazuki Endo, Shuya Ushimura, Yoshitaka Yoshimura, Yasutaka Yawaka

  Pediatric Dental Journal 30 (1) 72 - 79 0917-2394 2020/06 [Refereed][Not invited]
  
• 4-META/MMA-TBBレジンに惹起された炎症に対するN-acetyl cysteineの効果

  高橋 静香, 中村 光一, 八若 保孝

  小児歯科学雑誌 (公社)日本小児歯科学会 58 (大会抄録(誌上開催)号) 123 - 123 0583-1199 2020/04
• N-アセチルシステインによる歯根吸収抑制メカニズムの解析

  西見 光彦, 中村 光一, 久田 明奈, 八若 保孝

  小児歯科学雑誌 (公社)日本小児歯科学会 58 (大会抄録(誌上開催)号) 124 - 124 0583-1199 2020/04
• 当大学病院小児・障害者歯科外来における最近5年間の初診患者の実態調査

  趙 継美, 高木 康多, 高橋 静香, 中村 光一, 八若 保孝

  小児歯科学雑誌 (公社)日本小児歯科学会 58 (大会抄録(誌上開催)号) 227 - 227 0583-1199 2020/04
• 当大学病院小児・障害者歯科外来において来院回数が一回のみである初診患者の実態調査

  高木 康多, 趙 継美, 高橋 静香, 中村 光一, 八若 保孝

  小児歯科学雑誌 (公社)日本小児歯科学会 58 (大会抄録(誌上開催)号) 231 - 231 0583-1199 2020/04
• Effects of root canal irrigations on intracanal medication with calcium hydroxide effects in root external resorption models

  Akina Hisada, Koichi Nakamura, Yuki Toyota, Ayako Maeda, Toshihiro Yoshihara, Yasutaka Yawaka

  Pediatric Dental Journal 29 (1) 17 - 22 1880-3997 2019/04/01 

  Objective: The objective of the present in vitro study was to evaluate the influence of endodontic irrigation systems on the removal of smear layer and ion diffusion of calcium hydroxide through dentinal tubules in root external resorption models. Materials and methods: Forty single-rooted teeth were divided into four groups (G1, G2, G3, and G4) according to the irrigation regimens: G1, saline solution G2, 10% sodium hypochlorite with ultrasonic irrigation G3, 14% EDTA with ultrasonic irrigation G4, 14% EDTA with ultrasonic irrigation → 10% sodium hypochlorite with ultrasonic irrigation. Ultrasonic irrigation lasted 45 seconds and all the roots were irrigated with 2 mL of saline solution. In experiment 1, the samples were observed on the root canal wall using scanning electron microscope and the percentage of opened dentinal tubules (POD) was calculated. Experiment 2 evaluated the diffusion of calcium ions through dentinal tubules. Results: In the middle region of root canals, the mean POD values were 0.11, 5.02, 82.17 and 96.72 in G1, G2, G3, and G4, respectively. In the apical region of root canals, the mean POD values were 0.06, 0.43, 4.41, and 12.70 in G1, G2, G3, and G4, respectively. The diffusion of calcium ions in G4 was significantly high in all groups. Conclusion: This study demonstrated that a combination of EDTA and sodium hypochlorite with ultrasonic irrigation was most effective in removing the smear layer and ion diffusion from the root canal to the surrounding media.
• Daily life habits associated with eveningness lead to a higher prevalence of dental caries in children

  Shinya Nishide, Toshihiro Yoshihara, Hirohisa Hongou, Takeshi Kanehira, Yasutaka Yawaka

  Journal of Dental Sciences 14 302 - 308 2019/04
• 自動pHサイクル装置を用いた歯冠修復材料の脱灰抑制の影響

  遠藤 一樹, 中村 光一, 八若 保孝

  北海道歯学雑誌 北海道歯学会 39 (2) 87 - 93 0914-7063 2019/03 

  フッ素はエナメル質を強化し、う蝕予防に役立つことが知られている。またフッ素徐放性を有する歯冠修復材料は、二次う蝕予防に効果的だと言われている。本研究は自動pHサイクル装置を使用して、歯冠修復材料ならびにフッ化物処理がエナメル質に与える影響を明らかにし、脱灰溶液中に溶出する元素との相関について検討することを目的とした。歯冠修復材料にはZ100(3M ESPE、USA)、ビューティフィルII(BF:松風、京都)、フジIXGPエクストラカプセル(フジIX:ジーシー、東京)を使用した。ヒト大臼歯に各材料を充填したのちに切断し、薄型切片試料を作製した。その後、自動pHサイクル装置を使用し、試料を脱灰した。フッ化物処理は18.4mMのNaF溶液に試料を1日1回5分間浸漬させて行った。材料周囲エナメル質のTransverse Microradiographyを撮影し、ΔIntegrated Mineral Loss(ΔIML)を求めた。また、各材料ブロックを作製し、脱灰溶液に浸漬させ、材料から溶出したフッ素とストロンチウムを定量した。フッ化物未処理群では2〜4週においてBF群とフジIX群がZ100群と比較してΔIMLが有意に低かった。BF群とフジIX群の間には有意差が認められなかった。フッ化物処理群においても同様の傾向が認められた。フッ化物処理の有無で比較した場合、同一材料間では1週においてBF群ならびにフジIX群で有意差が認められた。フッ素とストロンチウムの溶出はBF群とフジIX群から認められ、両元素ともフジIX群からの溶出が有意に多かった。Z100群からは元素の溶出が認められなかった。また、材料からのフッ素とストロンチウムの溶出が確認できた歯冠修復材料周囲のエナメル質では、ΔIMLが有意に低くなった。(著者抄録)
• Nano porous silicaの歯科応用への可能性

  中村 光一, 八若 保孝

  小児歯科学雑誌 (公社)日本小児歯科学会 57 (1) 98 - 98 0583-1199 2019/02
• Immunolocalization of podoplanin/E11/gp38, CD44, and endomucin in the odontoblastic cell layer of murine tooth germs

  Naznin K, Hasegawa T, Nagai T, Yamamoto T, Miyamoto-Takasaki Y, Hongo H, Abe M, Haraguchi M, Yamamoto T, Yimin Qiu Z, Sasaki M, Kuroshima S, Ohshima H, Freitas PHL, Li M, Yawaka Y, Amizuka N

  Biomed Res 40 (4) 133 - 143 0388-6107 2019 [Refereed][Not invited]
   

  In this study, we attempted to localize the immunoreactivities of podoplanin/E11/gp38 and CD44, a counterpart possessing a high affinity to podoplanin/E11/gp38, as well as endomucin-immunoreactive blood vessels in the regions of odontoblast layers and the underlying sub-odontoblastic layers in murine tooth germs. Endomucin-reactive small blood vessels were scattered throughout the dental papillae of the tooth germs at postnatal day 1 but came to be localized close to the odontoblast/sub-odontoblastic layers until day 3. After postnatal day 5, small blood vessels were seen in odontoblast cell layers, while blood vessels with relatively larger diameters were seen forming in sub-odontoblastic layers. Immunoreactivities of podoplanin/E11/gp38 and CD44 were not detectable in the cells of dental papillae facing the inner enamel epithelium at postnatal day 1. However, at around postnatal days 3-5, podoplanin/E11/gp38 was localized in the odontoblast layer but not in the sub-odontoblastic layer, whereas CD44 was observed in the sub-odontoblastic layer but not in the odontoblast layer. The exclusive immunolocalization of podoplanin/E11/gp38 and CD44 in the odontoblast layers and sub-odontoblastic layers was seen after postnatal day 3 of the tooth germs, when the mesenchymal cells of dental papillae have already differentiated into mature odontoblasts at the cusp tip. Taken together, it seems likely that endomucin-reactive small blood vessels extended to the podoplanin/E11/gp38-positive odontoblast layers, whereas endomucin-reactive large blood vessels were already present in CD44-immmunopositive sub-odontoblastic layer, indicating the cellular regulation on the vascularization of endomucin-reactive endothelial cells during odontogenesis of the tooth germs.
• Patients with SATB2-associated syndrome exhibiting multiple odontomas.

  Kikuiri T, Mishima H, Imura H, Suzuki S, Matsuzawa Y, Nakamura T, Fukumoto S, Yoshimura Y, Watanabe S, Kinoshita A, Yamada T, Shindoh M, Sugita Y, Maeda H, Yawaka Y, Mikoya T, Natsume N, Yoshiura KI

  Am J Med Genet A. 176 (12) 2614 - 2622 1552-4825 2018/12 [Refereed][Not invited]
   

  © 2018 Wiley Periodicals, Inc. Special AT-rich sequence-binding protein 2 (SATB2)-associated syndrome (SAS) is characterized by alterations of SATB2. Its clinical features include intellectual disability and craniofacial abnormalities, such as cleft palate, dysmorphic features, and dental abnormalities. Here, we describe three previously undiagnosed, unrelated patients with SAS who exhibited dental abnormalities, including multiple odontomas. Although isolated odontomas are common, multiple odontomas are rare. Individuals in families 1 and 3 underwent whole-exome sequencing. Patient 2 and parents underwent targeted amplicon sequencing. On the basis of the hg19/GRCh37 reference and the RefSeq mRNA NM_001172517, respective heterozygous mutations were found and validated in Patients 1, 2, and 3: a splice-site mutation (chr2:g.200137396C > T, c.1741-1G > A), a nonsense mutation (chr2:g.200213750G > A, c.847C > T, p.R283*), and a frame-shift mutations (chr2:g.200188589_200188590del, c.1478_1479del, p.Q493Rfs*19). All mutations occurred de novo. The mutations in Patients 1 and 3 were novel; the mutation in Patient 2 has been described previously. Tooth mesenchymal cells derived from Patient 2 showed diminished SATB2 expression. Multiple odontomas were evident in the patients in this report; however, this has not been recognized previously as a SAS-associated phenotype. We propose that multiple odontomas be considered as an occasional manifestation of SAS.
• Oral findings in a patient with megacystis microcolon intestinal syndrome: A case report.

  Chihiro Takasaki, Toshihiro Yoshihara, Yasutaka Yawaka

  Pediatr Dent J 28 (2) 57 - 61 2018/08 [Refereed][Not invited]
  
• Calcium Charge and Release of Conventional Glass-Ionomer Cement Containing Nanoporous Silica.

  Nakamura K, Abe S, Minamikawa H, Yawaka Y

  Materials (Basel, Switzerland) 11 (8) 2018/07 [Refereed][Not invited]
  
• 日本小児歯科学会主催教育ワークショップの実施 大学間のバリエーションの把握

  八若 保孝, 内川 喜盛, 香西 克之, 飯沼 光生, 早崎 治明, 清水 武彦, 佐藤 昌史, 中村 光一, 木本 茂成

  日本歯科医学教育学会総会・学術大会プログラム・抄録集 (一社)日本歯科医学教育学会 37回 126 - 126 2018/07
• Effectiveness of wiping during oral care by guardians of children with severe motor and intellectual disabilities at home

  Takai Rihito, Oshima Shohei, Nakamura Koichi, Yawaka Yasutaka

  Journal of the Japanese Society for Disability and Oral Health 一般社団法人 日本障害者歯科学会 39 (1) 1 - 7 0913-1663 2018/02 

  Purpose：To clarify the effectiveness of wiping during oral care by guardians at home, and factors associated with salivary bacterial count.

  Method：The participants were 20 children with severe motor and intellectual disabilities （SMID） （mean age 5.5±3.8 years old） requiring both mechanical ventilator and tube-feeding. The survey was conducted during home-visit dental treatment. Guardians were instructed to do oral care （brushing their children's teeth for 2 minutes and wiping the inside of the oral cavity with gauze）. They were taught how to wipe before oral care. Suction during brushing was carried out in case guardians performed brushing on a daily basis. The saliva was taken from the floor of the mouth, and the number of bacteria in saliva was measured by a bacteria detection apparatus （Panasonic Healthcare Co., Ltd.）. Collection and measurement were conducted before brushing, after brushing, and after wiping. The correlations between the number of bacteria taken before brushing and information regarding patient characteristics such as method of feeding, use of mechanical ventilator, existence of tracheostomy, existence of continuous suction, and existence of swallowing were examined statistically.

  Results：The number of bacteria in saliva decreased significantly from before and after brushing to after wiping. There was no significant correlation between the existence of suction during brushing and variation of salivary bacterial count before and after brushing. The independent variables shown by univariate analysis to have a significant relationship with salivary bacterial count before brushing were use of mechanical ventilator, existence of tracheostomy, and existence of swallowing. Multiple regression analysis identified existence of swallowing as an independent associated factor for salivary bacterial count.

  Conclusion：Wiping was an effective method to decrease bacteria after brushing. Children who do not swallow had larger numbers of bacteria in saliva before brushing. These findings indicated that it is important for children who do not swallow to have their oral cavity wiped after tooth-brushing.

• Estimation of controlled drug-release behavior of nano-porous silica micro particles and their biocompatibility

  Eri Seitoku, Yuko Era, Ko Nakanishi, Yosuke Bando, Shinichi Kakuda, Koichi Nakamura, Teruo Kusaka, Shigeaki Abe, Mariko Nakamura, Yasutaka Yawaka, Junichiro Iida, Yasuhiro Yoshida, Hidehiko Sano

  Nano Biomedicine 9 (2) 112 - 116 2185-4734 2018 [Refereed][Not invited]
   

  In this study, we investigated the controlled release behavior of a model drug from nanoporous silica microparticles (NPSM) contained in dental glass ionomer cement (GIC). NPSM released model drug molecules gradually in water for 2 weeks when they were contained in GIC. In contrast, GIC-only specimens released the molecule rapidly. To estimate the cytocompatibility of NPSM, osteoblastic cells were exposed to particles with various concentrations. At a concentration of 30 ppm, cell viability remained identical to that without exposure. In addition, mixing the particles did not affect their mechanical properties. These results suggest that NPSM can be used as a sustainable drug-release dental material.
• Root canal treatment of traumatized permanent teeth with external root resorption

  Yasutaka Yawaka, Yuki Toyota, Akina Hisada, Ayako Maeda, Shohei Inoue, Toshihiro Yoshihara

  Hokkaido Journal of Dental Science 北海道歯学会 38 (Special issue) 122 - 129 0914-7063 2017/09 [Not refereed]
   

  External root resorption is an important challenge in the preservation of traumatized teeth. External root resorption is observed in cases of replanted teeth from dental trauma. Root canal dressing containing calcium hydroxide (Ca(OH)2) is one recommended clinical approach for external root resorption treatment. However, complete control of external resorption may not be possible due to certain factors, such as the smear layer, which is formed by reaming and filing during root canal treatments. The smear layer plugs dentinal tubules and inhibits the effects of Ca(OH)2 as a root canal dressing material. Our study showed that root canal irrigation with ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) with an ultrasonic device is the most effective method to remove the smear layer. Additionally, we observed an alkaline environment at the outer root surface due to ion diffusion from Ca(OH)2 following this treatment. As a result, the combined use of EDTA and NaOCl with an ultrasonic device for root canal irrigation led to good control of external root resorption.
• Effectiveness of Rubrics and Reflection Process Introduced to Basic Dental Practice Education for Pediatric Dentistry

  Chihiro Takasaki, Yoshiaki Sato, Yoshiaki Chihiro Takasaki, Nobuki Iwadera, Risa Taneichi, Yasutaka Yawaka

  The Japanese Journal of Pediatric Dentistry 55 (3) 364 - 374 2017/06 [Refereed][Not invited]
  
• 小児歯科学臨床基礎実習に試行導入したルーブリックと振り返りに対する有効性の検討

  高崎千尋, 佐藤嘉晃, 岩寺信喜, 種市梨紗, 八若保孝

  小児歯科学雑誌 55 (3) 364 - 374 2017/06 [Refereed][Not invited]
  
• Removal of smear layer by various root canal irrigations in primary teeth

  Yuki Toyota, Toshihiro Yoshihara, Akina Hisada, Yasutaka Yawaka

  Pediatric Dental Journal 27 (1) 8 - 13 1880-3997 2017/04/01 [Refereed][Not invited]
   

  Purpose Proper root canal irrigation is essential for endodontic treatment. To evaluate the effectiveness of several root irrigation regimens, the extent of the removal of smear layer from the root canal in primary teeth was analyzed. Methods Fifteen extracted human primary teeth were divided into five groups and subjected to the following irrigation regimes: Group 1, needle irrigation with saline Group 2, needle irrigation with 5% sodium hypochlorite (NaOCl) Group 3, ultrasonic irrigation with 5% NaOCl Group 4, needle irrigation with 14% ethylene diamine tetraacetic acid (EDTA) Group 5, ultrasonic irrigation with 14% EDTA. The percentage of open dentinal tubules (POD) in the irrigated root canal was analyzed using a scanning electron microscope. Results POD for Groups 4 and 5 were significantly higher than Groups 1, 2, and 3 (p <  0.01, respectively). POD for Group 3 was significantly higher than Groups 1 and 2 (p <  0.01, respectively). By contrast, in Groups 4 and 5, erosive effects such as enlargement of orifices of dental tubules were observed. In Group 3, the smear layer was removed without erosion. Conclusion These results suggest that root canal irrigation with NaOCl using an ultrasonic effectively removed smear layer from the root canal in primary teeth.
• Effect of fluoride-releasing fissure sealants on enamel demineralization

  Koichi Nakamura, Shigeaki Abe, Hajime Minamikawa, Yasutaka Yawaka

  Pediatric Dental Journal 27 (1) 56 - 64 1880-3997 2017/04/01 [Refereed][Not invited]
   

  Objective The purpose of this study was to investigate the effect of three types of fissure sealant (resin-based fissure sealant, resin-based fissure sealant containing S-PRG filler, and resin-modified glass ionomer cement (RMGIC)-based fissure sealant) on the surrounding enamel. Materials and methods Human deciduous molars were filled with fissure sealants and cut into 200 μm sections. Using an automatic pH-cycling system, the specimens were repeatedly demineralized and remineralized for 5 weeks. After automatic pH-cycling, integrated mineral loss (ΔIML) of the enamel around the fissure sealant was calculated. Twelve blocks of each fissure sealant were exposed to 10 mL of distilled deionized water at pH 6.3. Fluoride ion release, strontium ion release, and pH changes of the water were measured every week for 5 weeks. Results The BeautiSealant and FujiIIILC sealant groups had a significantly lower mean ΔIML at 5 weeks than the control group. The rate of fluoride and strontium ion release was significantly greater for the FujiIIILC sealant group than that for the Teethmate F-1 2.0 and BeautiSealant groups. Conclusion Fissure sealants that released a lot of fluoride and strontium ions showed decreased enamel demineralization.
• Charge and controlled release of epigallocatechin gallate by glass ionomer cement containing nanoporous silica particles.

  Nakamura K, Nakanishi K, Bando Y, Hasebe A, Hyono A, Abe S, Shibata K, Yoshida Y, Iida J, Yawaka Y

  Nano Biomedicine 9 (1) 29 - 34 2017/01 [Refereed][Not invited]
  
• Assessment of the inhibitory effects of fissure sealants on the demineralization of primary teeth using an automatic pH-cycling system

  Shuya Ushimura, Koichi Nakamura, Yasuhiro Matsuda, Hajime Minamikawa, Shigeaki Abe, Yasutaka Yawaka

  DENTAL MATERIALS JOURNAL 35 (2) 316 - 324 0287-4547 2016/04 [Refereed][Not invited]
   

  In this study, we examined the effects of fissure sealants on inhibition of demineralization of primary teeth using an automatic pH cycling system. Three fissure sealants were used: Teethmate F-1 2.0 (TM), BeautiSealant (BS), and Fuji III LC (IIILC). Using an automatic pH-cycling system, the specimens (n=12) were repeatedly demineralized and remineralized. Specimens were subjected to transverse microradiography (TMR), and changes in integrated mineral loss (IML) and lesion depth (Ld), indicated as Delta IML and Delta Ld, respectively, were calculated. In addition, fluoride levels in the enamel were assessed using microparticle-induced gamma ray emission/particle-induced X-ray emission (n=3). IIILC showed the lowest values for Delta IML and Delta Ld, followed by BS and then TM. The highest amount of fluorine in the enamel was observed for IIILC, followed by TM and BS. All fissure sealants inhibited demineralization in primary teeth.
• Estimation of Biocompatibility of Nano-Sized Ceramic Particles with Osteoblasts, Osteosarcomas and Hepatocytes by Static and Time-Lapse Observation

  Abe S, Seitoku E, Iwadera N, Hamba Y, Yamagata S, Akasaka T, Kusaka T, Inoue S, Yawaka Y, Iida J, Sano H, Yonezawa T, Yoshida Y

  J Biomed Nanotechnol. 12 (3) 472 - 480 1550-7033 2016/03 [Refereed][Not invited]
   

  We assessed the biocompatibility of nano-sized ceramic particles with several cells types. Though these particles have less than 100 nm in diameter, they act as submicron-sized particles in saline by aggregation that was estimated using laser diffraction particle size analysis (LDS). they act as submicro-sized particles in saline by aggregation based on laser diffraction particle size analysis (LDS). Several types of cells (osteoblasts, osteosarcoma and hepatocyte cells) were exposed to these particles and their cytocompatibility was estimated. Not only the cytotoxic assay but also their static and dynamic morphology under nanoparticles exposure were investigated. The intercellular uptake of particles was determined using a confocal fluorescence microscope. The particles used in this study did not inhibit cellular activity or growth even when their concentrations were high. Only copper oxide particles caused acute cytotoxicity depending on the particle size. The cytotoxicity assay, dynamic behavior of the nanoparticle-exposed cells and their examination under a confocal fluorescence microscope suggests that the irritative reaction was induced by contact between the cells and particles, whereas eluted copper ions are not dominant factor. These results indicate that nano-sized particles used in this study have excellent biocompatibility except copper oxide ones.
• P-1-E12 在宅重症心身障害児者の唾液中細菌数に関連する因子についての検討

  高井 理人, 工藤 裕子, 中村 光一, 八若 保孝, 土畠 智幸

  日本重症心身障害学会誌 日本重症心身障害学会 41 (2) 248 - 248 1343-1439 2016 

  緒言重症心身障害児者（以下、重症児者）では合併症としての誤嚥性肺炎がしばしば問題となる。また、口腔内細菌が起炎菌となることが知られており、口腔ケアの重要性が周知されてきた。今回、在宅重症児者の唾液中細菌数を調査し、細菌数に影響を与える因子について検討したので報告する。方法当院患者のうち、訪問歯科診療を受けている在宅重症児者30名（1歳〜40歳、平均年齢13.7±9.7歳）を対象とし、調査期間は平成27年11月から平成28年1月までの3カ月間とした。調査は居宅訪問中（10時〜16時）に行い、舌下部に滅菌綿棒を10秒間浸して唾液を採取し、卓上細菌数測定装置（パナソニックヘルスケア社製）を用いて唾液中細菌数を測定した。また、全身状態（経管栄養、気管切開、人工呼吸器、唾液嚥下の有無）、口腔内状況（歯石、舌苔、齲蝕の有無）について調査し、それぞれの項目と唾液中細菌数との関連を統計学的に検討した。結果唾液中細菌数と有意な正の関連を示した項目は、気管切開「有」（p=0.027）、唾液嚥下「無」（p=0.010）、舌苔「有」（p=0.028）であった。考察唾液嚥下を認めない者の口腔内は、嚥下反射の低下により口腔内に唾液が長時間貯留するため口腔内細菌が増殖しやすい環境であると考えられる。また、気管切開の影響により嚥下運動が困難になっている可能性がある。舌苔の付着が多い者は、舌の運動性が低いため自浄作用が低下していると考えられ、口腔機能の低下が唾液中細菌数に影響を与えていると思われた。結語在宅重症児者において、嚥下機能や口腔機能が低下していると唾液中細菌数が多い。今後、この結果をもとに重症児者に対する誤嚥性肺炎の予防方法について検討する必要がある。
• 在宅人口呼吸器を使用する重症心身障害児に対する訪問歯科診療についての検討

  高井理人, 大島昇平, 中村光一, 八若保孝

  小児歯科学雑誌 55 (3) 382 - 389 2016 [Refereed][Not invited]
  
• Activation of inflammasome by Aggregatibacter actinomycetemcomitans

  阿部亜美, 佐伯歩, 長谷部晃, 原博志, 八若保孝, 柴田健一郎

  北海道歯学雑誌 北海道歯学会 35 (2) 123 - 132 0914-7063 2015/03/15 [Not refereed][Not invited]
   

  インフラマソームは多様な生理活性をもつ炎症性サイトカインのひとつであるIL-1βの産生を制御する細胞内センサーである。近年、IL-1βが関与する炎症性疾患の多くがこの細胞内センサーの活性化と関連している可能性が示唆され、病態解明の手がかりとしてインフラマソームが注目されている。歯周炎はその病態形成にIL-1βが重要な役割を果たすが、歯周炎とインフラマソームとの関連を示した報告はほとんどない。そこで、本研究では、侵襲性歯周炎の主な病原菌であり、感染性心内膜炎や敗血症などの全身疾患との関連も多く報告されているAggregatibacter actinomycetemcomitansの歯周疾患における病因論の一部を明らかにすることを目的とし、本菌によるインフラマソームの活性化について検証した。A.actinomycetemcomitansの生菌および死菌でA/Jマウス由来樹状細胞(XS106細胞)を刺激したところ、生菌、死菌ともにIL-1βの産生を誘導したが、A.actinomycetemcomitans培養上清では産生誘導はみられなかった。生菌および死菌でのIL-1β産生誘導活性はZ-VAD-FMKとZ-YVAD-FMKで有意に阻害された。さらに、これらのIL-1β産生誘導活性はcaspase-1ならびにNLRP3のノックダウンにより有意に減弱した。また、A.actinomycetemcomitans菌体はXS106細胞にネクローシス様細胞死を誘導し、その細胞死はIL-1βの産生を伴うことからピロトーシスであると考えられる。以上の結果から、A.actinomycetemcomitans菌体はXS106細胞においてNLRP3インフラマソームを活性化し、IL-1β産生ならびにピロトーシス誘導活性を有していることがわかった。(著者抄録)
• Disease specificity of anti-tryptophan hydroxylase-1 and anti-AIE-75 autoantibodies in APECED and IPEX syndrome

  Natsuko Chida, Ichiro Kobayashi, Shunichiro Takezaki, Masahiro Ueki, Yasuhiro Yamazaki, Silvia Garelli, Riccardo Scarpa, Reiko Horikawa, Masafumi Yamada, Corrado Betterle, Luigi D. Notarangelo, Yasutaka Yawaka, Tadashi Ariga

  CLINICAL IMMUNOLOGY 156 (1) 36 - 42 1521-6616 2015/01 [Refereed][Not invited]
   

  Autoantibodies to autoimmune enteropathy-related 75 kDa antigen (AIE-75) and villin are disease markers of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome which is characterized by a peripheral tolerance defect. On the other hand, anti-tryptophan hydroxylase-1 (TPH-1) antibodies are detected in autoimmune polyendocrinopathy, candidiasis, ectodermal dystrophy (APECED), a central tolerance defect, especially when complicated with gastrointestinal dysfunction. However, to date, anti-AIE-75 and anti-villin antibodies or anti-TPH-1 antibodies have not been tested in APECED or IPEX syndrome, respectively. In the present study, we confirmed the disease specificity of both anti-AIE-75 and anti-TPH-1, although anti-villin antibodies were detected in some patients with APECED. Our observation suggests that immunotolerance to AIE-75 depends on the peripheral mechanism, whereas the tolerance to TPH-1 depends on the central mechanisms. (C) 2014 Elsevier Inc. All rights reserved.
• 歯科診療に不協力な小児や障害者に対する歯科診療時の自律神経機能の評価方法についての検討

  星野 恵, 大島昇平, 種市梨紗, 北村かおる, 下地伸司, 川浪雅光, 八若保孝

  小児歯誌 53 (3) 390 - 398 2015 [Refereed][Not invited]
  
• 障害者に対する歯科診療が自律神経機能に及ぼす影響 －心拍変動解析を用いた評価－

  星野 恵, 大島昇平, 種市梨紗, 北村かおる, 下地伸司, 川浪雅光, 八若保孝

  北海道歯誌 36 (1) 4 - 13 2015 [Refereed][Not invited]
  
• 大学病院受診患者における喪失歯を参考とした長期的口腔管理に対する検討 障害者入所施設入居者について

  野島 靖子, 牛村 秀耶, 中村 光一, 大島 昇平, 八若 保孝, 森 貴幸, 江草 正彦

  障害者歯科 (一社)日本障害者歯科学会 34 (3) 386 - 386 0913-1663 2013/09
• Differential effects of repeated immobilization stress in early vs. late postnatal period on stress-induced corticosterone response in adult rats

  Yoshihara Toshihiro, Yawaka Yasutaka

  Neuroscience Letters Elsevier 534 30 - 34 0304-3940 2013/02/08 

  This study was performed in order to determine how immobilization stress in the early postnatal period or in the late postnatal period affects growth in the developing rat, and the response of the hypothalamus-pituitary-adrenocortical (HPA) axis in adult rats subjected to subsequent novel stresses. In addition, the effects of maternal deprivation (MD) within the same period of exposure to immobilization stress were also examined. We used two different types of immobilization stress and two different types of MD: immobilization stress for 30 min per day from postnatal day 7 (P7) to P13 (IS-E group); immobilization stress for 30 min from P15 to P21 (IS-L group); MD for 30 min per day from P7 to P13 (MD-E group); and MD for 30 min per day from P15 to P21 (MD-L group). The IS-E group showed a significant reduction in body weight that was maintained until at least P40 when compared with the control group. On the other hand, the IS-L group showed a significant reduction in body weight at only postnatal day (P) 20 when compared with the control group. Furthermore, the IS-E group showed a larger HPA response to novel stress than the IS-L and control groups in adulthood. The MD-E group showed a significant reduction in body weight that was maintained until at least P20 when compared with the control group, but did not show a larger HPA response to novel stress, except at T30 (30 min after exposure to novel stress) than the control group in adulthood. The MD-L group did not show a significant reduction in body weight or increased HPA response when compared with control rats. These results suggest that repeated immobilization stress, but not MD, in the early postnatal period induces long-term effects on growth and HPA response to novel stress in adulthood. (C) 2012 Elsevier Ireland Ltd. All rights reserved.
• Biocompatibility and biodistribution of several nano-sized ceramics particles

  Shigeaki Abe, Yusaku Hamba, Nobuki Iwadera, Tsukasa Akasaka, Shuichi Yamagata, Yasutaka Yawaka, Junichiro Iida, Motohiro Uo, Tetsu Yonezawa, Fumio Watari

  BIOCERAMICS 24 529-530 625 - + 1013-9826 2013 [Refereed][Not invited]
   

  We succeeded in determination the biodistribution of several nano-sized particles administered to mice through the tail vein. After administration, these particles were observed in the lung, liver and spleen. The distribution behaviors depend upon not only chemical species but also the particles size. To estimate their cytocompatibility, these particles were exposed to osteoblastic cell at several concentrations. When the concentration reached at 10 ppm, their viability remained at 80% or more even nano-sized particle contained rare earth element. Only CuO particles indicated the viability decrease. The effect depended on the particle size. These results suggested that the chemical species played a dominant key in the biodistribution and biocompatibility of nanoparticles compared with the size-effect.
• Influence of micro-/nano- particles on osteoblast-like cells: A static and time lapse observation

  Nobuki Iwadera, Shigeaki Abe, Tsukasa Akasaka, Yasutaka Yawaka, Fumio Watari

  BIOCERAMICS 24 529-530 374 - + 1013-9826 2013 [Refereed][Not invited]
   

  Cytotoxicity and cell behavior to micro / nano particles of TiO2 and CuO was evaluated using the viability measurement and time-lapse observation. After cultured, osteoblastic cells MC3T3-E1 were exposed to particles. After 24 hour exposure, their morphology was observed using a SEM and the viability was measured. Cells exposed to TiO2 indicated no or very low decrease of viability. The results were independent of the particle size. On the other hand, the viability of cells exposed to CuO decreased with the concentration, and showed the size dependence. The nano-sized CuO indicated higher toxicity compared with micro-sized one. Dynamic behavior of cells exposed to nano particles, was succeeded to observe in a time-lapse method for 24 hours. The observation showed that the cells exposed to CuO became dead after forming a spherical shape. This is consistent with the image taken by SEM. Time-lapse observation made it possible to see the dynamic reaction process from cell contact to particles at first, the following cell activity response and finally to cell death, which revealed a considerably different morphology from the static cell observed after fixation by conventional method.
• Biodistribution of Aqueous Suspensions of Carbon Nanotubes in Mice and Their Biocompatibility

  Shigeaki Abe, Sachiko Itoh, Daisuke Hayashi, Toshihisa Kobayashi, Takayuki Kiba, Tsukasa Akasaka, Motohiro Uo, Yasutaka Yawaka, Shin-Ichiro Sato, Fumio Watari, Tomoya Takada

  Journal of Nanoscience and Nanotechnology 12 (1) 700 - 706 1533-4880 2012/01/01 

  In this study, we prepared two-types of water-dispersible carbon nanotubes (CNTs) and investigated their biodistribution in mice as well as bio-/cyto-compatibility. After administration, their organs were excised at various post-injection times, then observed using both optical and transmission electron microscopy (TEM). The color of the liver and lung markedly darkened, suggesting that administered CNTs reached these organs. By TEM observation, the CNTs were found in the liver and lung. They were observed even in the kidney and spleen, though their distributions in those organs were very low compared with that in liver and lung. Therefore, most of the administered CNTs would be accumulated in the liver or lung. However, the time profile of the body weight of CNT-administered mice was close to that of control mice. In addition, we estimated the cytocompatibility of the water-dispersible CNTs for hepatocytes. According to a TNF-alpha assay of the cells cultured with CNTs, the expression level was almost the same as that of the control. These results suggested that the water-dispersible CNTs have good bio-/cyto-compatibility under this condition.
• Lesions of the ventral ascending noradrenergic bundles decrease the stress response to occlusal disharmony in rats

  Toshihiro Yoshihara, Yasutaka Yawaka

  NEUROSCIENCE LETTERS 503 (1) 43 - 47 0304-3940 2011/09 [Refereed][Not invited]
   

  Occlusal disharmony induced by placing an acryl cap on the lower incisors of rats is perceived as chronic stress. This chronic stress activates corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN), resulting in stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. The ventral ascending noradrenergic bundles (V-NAB) from the brainstem innervate the PVN. To investigate the relationship between the response of the HPA axis and the V-NAB, we examined changes in extracellular noradrenaline (NA) in the PVN and plasma corticosterone. the final output of the HPA axis, following occlusal disharmony in rats injected with 6-hydroxydopamine (6-OHDA), a specific catecholamine neurotoxin. 6-OHDA microinjection into the V-NAB reduced the magnitude of the responses of extracellular NA in the PVN and the plasma corticosterone to occlusal disharmony. Our results suggest that V-NAB to the PVN are involved in occlusal disharmony-induced activation of the HPA axis. (C) 2011 Elsevier Ireland Ltd. All rights reserved.
• Application of Imogolite, Almino-Silicate Nanotube, as Scaffold for the Mineralization of Osteoblasts

  Kosuke Ishikawa, Tsukasa Akasaka, Shigeaki Abe, Yasutaka Yawaka, Masaya Suzuki, Fumio Watari

  Bioceramics Development and Applications 1 D110133  2011/01 [Refereed][Not invited]
  
• Amino acid derivative-mediated detoxification and functionalization of dual cure dental restorative material for dental pulp cell mineralization.

  Minamikawa H, Yamada M, Iwasa F, Ueno T, Deyama Y, Suzuki K, Yawaka Y, Ogawa T

  Biomaterials 31 (28) 7213 - 7225 0142-9612 2010/10 [Refereed][Not invited]
   

  Current dental restorative materials are only used to fill the defect of hard tissues, such as dentin and enamel, because of their cytotoxicity. Therefore, exposed dental pulp tissues in deep cavities must be first covered by a pulp capping material like calcium hydroxide to form a layer of mineralized tissue. However, this tissue mineralization is based on pathological reaction and triggers long-lasting inflammation, often causing clinical problems. This study tested the ability of N-acetyl cysteine (NAC), amino acid derivative, to reduce cytotoxicity and induce mineralized tissue conductivity in resin-modified glass ionomer (RMGI), a widely used dental restorative material having dual cure mechanism. Rat dental pulp cells were cultured on untreated or NAC-supplemented RMGI. NAC supplementation substantially increased the percentage of viable cells from 46.7 to 73.3% after 24-h incubation. Cell attachment, spreading, proliferative activity, and odontoblast-related gene and protein expressions increased significantly on NAC-supplemented RMGI. The mineralization capability of cells, which was nearly suppressed on untreated RMGI, was induced on NAC-supplemented RMGI. These improved behaviors and functions of dental pulp cells on NAC-supplemented RMGI were associated with a considerable reduction in the production of intracellular reactive oxygen species and with the increased level of intracellular glutathione reserves. These results demonstrated that NAC could detoxify and functionalize RMGIs via two different mechanisms involving in situ material detoxification and antioxidant cell protection. We believe that this study provides a new approach for developing dental restorative materials that enables mineralized tissue regeneration.
• Anomaly of cervical vertebrae found on orthodontic examination: 8-year-old boy with cleft lip and palate diagnosed with Klippel-Feil syndrome

  Toshihiro Yoshihara, Junichi Suzuki, Yasutaka Yawaka

  ANGLE ORTHODONTIST 80 (5) 975 - 980 0003-3219 2010/09 [Refereed][Not invited]
   

  We incidentally encountered an anomaly of the cervical vertebrae during orthodontic examination of an 8-year-old boy with cleft lip and palate. Klippel-Feil syndrome was diagnosed by the orthopedic specialist to whom he had been referred for detailed examination. This case report shows the results of axial multislice-helical computed tomography with three-dimensional reconstructions of the cervical vertebrae. Furthermore, we evaluated the frequency of congenital anomalies on lateral cephalogram in patients with cleft lip and palate or cleft palate and non-cleft controls from among all patients in our orthodontic clinic. (Angle Orthod. 2010;80:975-980.)
• Osteoblastic cellular responses to aluminosilicate nanotubes, imogolite using Saos-2 and MC3T3-E1 cells

  Kosuke Ishikawa, Shigeaki Abe, Yasutaka Yawaka, Masaya Suzuki, Fumio Watari

  JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 118 (1378) 516 - 520 1882-0743 2010/06 [Refereed][Not invited]
   

  Imogolite is a naturally occurring hydrous aluminosilicate clay mineral. It has nano-tubular structure similar to that of single-walled carbon nanotubes. Imogolite is a subject of interest in the pedological field, but to date there has been no bioapplications of this substance. In this study, we investigated the cellular response of osteoblast-like cells to imogolite scaffolds. To reveal the morphology, proliferation and osteoblastic functional mineralization, we cultured human osteoblast-like cells (Saos-2) and mouse osteoblast-like cells (MC3T3-E1) on the scaffolds. The surface characteristics of the imogolite scaffold were drastically changed depending on the amount of imogolite on the dish. With the increase of imogolite concentration, the surface morphology of scaffolds changed from an island-like shape in random orientation to a self-organized fiber texture aligned in the same direction, and finally full coverage in a random orientation with plural layers. Both types of osteoblast were widely spread on the imogolite scaffolds compared to their appearance in a conventional culture dish (control). The proliferation of the two types of osteoblast showed potentially useful trends. In cellular function, there was greater mineralization of both types of osteoblast on imogolite scaffolds than that of the control. Saos-2 and MC3T3-E1 cells showed good biocompatibility in addition to the enhanced osteoblastic mineralization. Therefore, imogolite is expected to be useful as a scaffold material for bone tissue engineering. (C) 2010 The Ceramic Society of Japan All rights reserved.
• Regulation of microRNA expression by bone morphogenetic protein-2

  Mari M. Sato, Yasutaka Yawaka, Masato Tamura

  INTERFACE ORAL HEALTH SCIENCE 2009 158 - 160 2010 [Refereed][Not invited]
   

  MicroRNAs (miRNAs) are small noncoding RNAs that are emerging as important posttranscriptional gene regulators. Many miRNAs are expressed in a tissue-specific manner, which suggests that they have specific biological roles in the specification of tissues. In this chapter, we summarize the currently available data on the regulation of miRNA expression by bone morphogenetic protein (BMP)-2. These studies open new avenues for the study of BMP signaling and miRNA biogenesis.
• Various nanotube scaffolds for cell proliferation

  F. Watari, T. Akasaka, K. Ishikawa, M. Matsuoka, E. Hirata, N. Terada, A. Yokoyama, M. Uo, S. Itoh, Y. Yawaka, M. Suzuki, N. Takashi, Y. Totsuka, Y. Kitagawa, S. Abe, I. D. Rosca, Y. Kuboki, Y. Bando

  Materials Science Forum 631-632 181 - 186 0255-5476 2010 

  Carbon nanotubes (CNT) and their derivatives with different structure and compositions have unique features. In the present study, cell proliferation was performed on various nanotubes such as single walled CNTs, multiwalled CNTs and imogolite which is nanotubes of aluminosilicate. SEM observation of the growth of osteoblast-like cells cultured on CNTs showed the morphology fully developed for the whole direction, which was different from that extended to the one direction on the usual scaffold. Numerous filopodia were grown from cell edge, extended far long and combined with CNT meshwork. Apatite precipitation in simulated body fluid, affinity for proteins and saccharides, and nanosize meshwork structure with large porosity would be the properties responsible for these cell adhesion and growth. Imogolite showed the similar properties to CNTs. Nanotubes could be the favorable materials for biomedical applications. © (2010) Trans Tech Publications.
• High Functional Expression of Osteoblasts on Imogolite, Aluminosilicate Nanotubes

  Ishikawa K, Akasaka T, Yawaka Y, Watari F

  J Biomed Nanotechnol. 6 (1) 59 - 65 1550-7033 2010/01 [Refereed][Not invited]
   

  Imogolite is a naturally occurring aluminosilicate clay mineral with a nanotube structure of 2 nm diameter and 60 nm-2 mu m length. In this study, synthetic imogolite nanotubes were applied to cell culture and the properties as a scaffold were compared with those of a conventional culture dish and a carbon nanotube (CNT) scaffold. The surface characteristics of the imogolite scaffold were drastically changed with the amount of coated imogolite on the dish. With the increase of imogolite concentration, the surface morphology of the scaffolds changed from an island-like shape in random orientation to a self-organized fiber texture aligned in the same direction, and finally full coverage in a random orientation with plural layers. Silicon releasability of the scaffolds was increased with the amount of coated imogolite. Mouse osteoblast-like cells (MC3T3-E1) cultured on imogolite showed a flat-form morphology and a cytoskeleton developed in all directions in contrast to a spindle-shaped morphology developed in one direction on cell culture dishes and CNT scaffolds. The proliferation and osteoblastic functions in ALP activity and mineralization showed similar increasing tendency. The largest values were obtained from the scaffold with a high concentration of imogolite. The results indicated good biocompatibility between the cells and imogolite scaffold and the enhancement effect of proliferation and osteoblastic differentiation.
• Present Situation and Possibility of Root Canal Treatments in Primary Teeth

  YAWAKA Yasutaka

  The Japanese Journal of Pediatric Dentistry Japanese Society of Pediatric Dentistry 47 (5) 710 - 718 0583-1199 2009/12/25 

  In the root canal treatments of primary teeth, a good prognosis can be acquired by the controls of inflammation and root resorption. However, on account of the complicated root canal forms in pri mary teeth and physiological root resorption with exchange to permanent successors, there are some cases in which the ideal treatments do not become possible. In the current stage, it is important to effectively remove bacterial bio-films in root canals and smear layers with reaming and filing on root canal walls. Root canal irrigation with sodium hypochlorite with ultra sonic and/or EDTA with ultra sonic can remove bio-films and smear layers on the root canal walls. By means of irrigation, we can sufficiently utilize the effects of calcium hydroxide and other root canal medications. And the result,the prognosis of the root canal treatments seems to become good. In addition, our efforts are necessary for the development and discovery of good methods in root canal treatments including the root repair mechanism with cementum deposition of primary teeth.
• Occlusal disharmony increases stress response in rats

  Toshihiro Yoshihara, Risa Taneichi, Yasutaka Yawaka

  NEUROSCIENCE LETTERS 452 (2) 181 - 184 0304-3940 2009/03 [Refereed][Not invited]
   

  Repeated or chronic stress is known to produce structural and functional changes in the rat brain, and in particular, alter the response of the hypothalamic-pituitary-adrenal (HPA) axis to subsequent new stress. Occlusal disharmony via placement of acryl cap on the lower incisors of rats is perceived as chronic stress. To determine the response of the HPA axis to subsequent new stress in rats with occlusal disharmony, we measured plasma corticosterone levels in these rats after subjecting them to new stress. Plasma corticosterone levels in rats with and without incisal cap increased and reached a peak 30 min after exposure to the new stress. However, a later decrease in plasma corticosterone levels from peak levels was found in rats with incisal cap compared with rats without incisal cap. This finding suggests that occlusal disharmony alters the response of the HPA axis to subsequent new stress. (C) 2009 Elsevier Ireland Ltd. All rights reserved.
• Visualization of invasion into the body and internal diffusion of nanoparticles

  F. Watari, S. Abe, I. D. Rosca, A. Yokoyama, M. Uo, T. Akasaka, N. Takashi, Y. Totsuka, E. Hirata, M. Matsuoka, K. Ishikawa, S. Itoh, Y. Yawaka

  BIOCERAMICS 21 396-398 569 - 572 1013-9826 2009 [Refereed][Not invited]
   

  Nanoparticles may invade directly into the internal body through the respiratory or digestive system and diffuse inside body. The behavior of nanoparticles in the internal body is also essential to comprehend for the realization of DDS. Thus it is necessary to reveal the internal dynamics for the proper treatments and biomedical applications of nanoparticles. In the present study the plural methods with different principles such as X-ray scanning analytical microscope (XSAM), MRI and Fluorescent microscopy were applied to enable the observation of the internal diffusion of micro/nanoparticles in the (1) whole body level, (2) inner organ level and (3) tissue and intracellular level. Chemical analysis was also done by ICP-AES for organs and compared with the results of XSAM mapping.
• Crystal growth by fluoridated adhesive resins

  Masanori Hashimoto, Kouichi Nakamura, Masayuki Kaga, Yasutaka Yawaka

  DENTAL MATERIALS 24 (4) 457 - 463 0109-5641 2008/04 [Refereed][Not invited]
   

  Objective. This investigation was carried out to evaluate the long-term effects of fluoride-releasing adhesive resins on structural changes in standardized fluid-filled gaps simulating microleakage between the materials and the tooth surface in vitro. Methods. Three commercially available fluoride -releasing resin adhesives (One-Up Bond F, OptiBond Solo, and Reactmer Bond) were used in this study. Cured disks of resin adhesive were placed over flat human tooth surfaces (enamel and dentin), separated by a standardized 40 mu m interfacial gap and stored in distilled water for 24 h (control group) or 1000 days (experimental group). After 1000 days of water storage, the resins were detached from the teeth and the opposing surfaces were examined by scanning electron microscopy (SEM). In addition, chemical structural analysis was performed by laser-Raman spectroscopy. Results. The SEM microphotographs showed numerous crystal types on the enamel, dentin, and resin surfaces after 1000 days of water storage for OptiBond Solo and Reactmer Bond. However, there was no crystal formation in the control specimens and the aged specimens of One-Up Bond F. Raman analysis showed several peaks (463, 618, and 990 cm(-1)) from the crystals of OptiBond Solo that were not identified in the enamel, dentin, or cured resin. Significance. In conclusion, two of the three tested fluoride -release resin adhesives (OptiBond Solo and Reactmer Bond) have the ability to induce crystal growth within gaps between the adhesive and teeth in long-term water storage. These results suggest that the two adhesive resins have self-reparative ability with regard to bond leakage. (C) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
• セルフエッチングシステムにおける溶媒が象牙質接着界面に及ぼす影響

  吉田 英史, 宇野 滋, 野田坂 佳伸, 加我 正行, 八若 保孝, 平野 進

  歯科材料・器械 (一社)日本歯科理工学会 26 (2) 229 - 229 0286-5858 2007/04
• オールインワン・アドヒーシブによる象牙質接着界面の脱灰層とその微細構造

  吉田 英史, 宇野 滋, 野田坂 佳伸, 加我 正行, 八若 保孝, 平野 進

  歯科材料・器械 (一社)日本歯科理工学会 25 (2) 107 - 107 0286-5858 2006/04
• 試作ペースト/ペーストタイプ修復用グラスアイオノマーセメントのコンディショナーの役割とフッ素徐放について

  岩淵 英明, 八若 保孝, 吉田 英史, 藤原 百合, 加我 正行

  小児歯科学雑誌 (公社)日本小児歯科学会 43 (1) 126 - 126 0583-1199 2005/03
• NaF溶液による光硬化型グラスアイオノマーセメントシーラントのフッ素のリチャージ効果

  加我 正行, 吉田 英史, 八若 保孝, 小口 春久

  口腔衛生学会雑誌 (一社)日本口腔衛生学会 54 (2) 158 - 159 0023-2831 2004/04
• 各種予防填塞材が有するフッ素の徐放とリチャージ効果

  加我 正行, 中尾 加代子, 菊池 友絵, 吉田 英史, 八若 保孝, 小口 春久

  小児歯科学雑誌 (公社)日本小児歯科学会 41 (2) 358 - 358 0583-1199 2003/04
• Expression of receptor activator of NF-kappa B ligand and osteoprotegerin in culture of human periodontal ligament cells

  T Hasegawa, Y Yoshimura, T Kikuiri, Y Yawaka, S Takeyama, A Matsumoto, H Oguchi, T Shirakawa

  JOURNAL OF PERIODONTAL RESEARCH 37 (6) 405 - 411 0022-3484 2002/12 [Refereed][Not invited]
   

  The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), are the important proteins implicated in osteoclastogenesis. In this study, we investigated the expressions of RANKL and OPG in cultured human periodontal ligament (PDL) cells and their roles in osteoclastogenesis. Northern blotting revealed that the OPG mRNA was downregulated remarkably by application of 10(-8) m one-alpha, 25-dihydroxyvitamin D-3 [1,25-(OH)(2)D-3] and 10(-7) m dexamethasone (Dex). In contrast, RANKL mRNA was up-regulated by the same treatment. Western blotting demonstrated decrease of OPG by the application of 1,25-(OH)(2)D-3 and Dex. Tartrate-resistant acid phosphatase-positive multinuclear cells were markedly induced when the PDL cells were cocultured with mouse bone marrow cells in the presence of an anti-OPG antibody together with 1,25-(OH)(2)D-3 and Dex. These results indicate that PDL cells synthesize both RANKL and OPG and that inactivation of OPG may play a key role in the differentiation of osteoclasts.
• 歯肉に膨隆を認めた3症例

  八若 保孝, 菊地 友絵, 中尾 加代子, 福井 亜実, 小口 春久

  小児歯科学雑誌 (公社)日本小児歯科学会 40 (2) 412 - 412 0583-1199 2002/04
• 本学歯学部附属病院小児歯科外来における初診患者の実態調査 5年間(平成8〜12年度)の動態(1) 初診時について

  菊地 友絵, 中尾 加代子, 弘中 祥司, 八若 保孝, 加我 正行, 小口 春久

  小児歯科学雑誌 (公社)日本小児歯科学会 40 (1) 207 - 207 0583-1199 2002/03
• 本学歯学部附属病院小児歯科外来における初診患者の実態調査 5年間(平成8〜12年度)の動態(2) その後の動向について

  中尾 加代子, 菊地 友絵, 弘中 祥司, 八若 保孝, 加我 正行, 小口 春久

  小児歯科学雑誌 (公社)日本小児歯科学会 40 (1) 207 - 207 0583-1199 2002/03
• ヒト破歯細胞に関する微細形態学的研究 : 感染根管処置経験乳歯について

  長内 正数, 土門 卓文, 八若 保孝, 小口 春久

  小児歯科学雑誌 一般社団法人 日本小児歯科学会 37 (2) 325 - 325 0583-1199 1999/04/01
• 乳歯歯根の病的吸収部位に添加されたセメント質について

  八若 保孝, 長内 正数, 秋山 明美, 原田 理恵, 小口 春久

  小児歯科学雑誌 一般社団法人 日本小児歯科学会 35 (2) 228 - 228 0583-1199 1997/04/01
• 上顎前歯部歯槽堤に発生した先天性神経線維腫の1例

  秋山 明美, 八若 保孝, 原田 理恵, 長内 正数, 雨宮 璋, 小口 春久

  小児歯科学雑誌 一般社団法人 日本小児歯科学会 35 (2) 274 - 274 0583-1199 1997/04/01
• Histological Study of the Invasion of Microorganisms into the Root Canal and Dentinal Tubules of Pulpless Deciduous Teeth : Transmission Electron Microscopic Observation

  YAWAKA Yasutaka, TANIGUCHI Akikazu, KOJIMA Hiroshi, OGUCHI Haruhisa

  The Japanese Journal of Pediatric Dentistry 一般社団法人 日本小児歯科学会 33 (3) 581 - 593 0583-1199 1995/06/25 

  The root canal and intracanal wall of three deciduous teeth which were extracted due to advanced apical periodontitis and sever abnormal root resorption were examined by means of light and transmission electron microscopes.
  There was a large quantity of microorganisms in the root canal and on the intracanal wall in all specimens. Invasion of microorganisms into the dentinal tubules in the coronal third in all specimens was observed, and in the middle third in two specimens. However, the apical third in all specimens showed no invasion of microorganisms into the dentinal tubules. According to our previous study and this study, therefore, it is suggested that before the microorganisms invade into the dentinal tubules, inflammation certainly breaks out and advances in the apical and furcation regions in deciduous teeth.
  Very small electron-denced materials adhered irregularly on the dentinal tubule wall in the apical region. These materials were unknown, but it was thought that they were intimately related to the infection and inflammation in the apical region. Also, partial cementum-like tissue deposition on intracanal wall in the apical region showed the restration mechanism in the process of abnormal root resorption.
• Histological Study of the Invasion of Microorganisms into the Dential Tubules of Pulples Deciduous Teeth : Observation under Scanning Electron Microscopy

  TANIGUCHI Akikazu, YAWAKA Yasutaka, KOJIMA Hiroshi, OGUCHI Haruhisa

  The Japanese Journal of Pediatric Dentistry 一般社団法人 日本小児歯科学会 33 (3) 572 - 580 0583-1199 1995/06/25 

  Specimens were prepared from six deciduous molars which were extracted due to advanced periapical lesions. Localization of the microorganisms in the dential tubules of the root was investigated histologically under scanning electron microscopy.
  The invasion of the microorganisms into the dentinal tubules of the root was observed in six specimens out of ten. In most cases, the invasion of the microorganisms into the dentinal tubules was observed in the coronal third especially around the entrance to the root canal. In the region of the apical third, only one specimen showed a bacterial invasion which was superficial and limited in some tubules.
  These observations indicated that the invasion of the microorganisms into the dential tubules was not especially noticable in the middle or apical portions of the root of pulpless deciduous teeth.
• ヒト乳歯歯根吸収面に存在する破歯細胞の微細形態学的研究

  長内 正数, 八若 保孝, 脇田 稔, 小口 春久

  小児歯科学雑誌 一般社団法人 日本小児歯科学会 33 (2) 261 - 261 0583-1199 1995/04/01
• 逆生埋伏上顎中切歯の早期開窓牽引症例

  小島 寛, 八若 保孝, 小口 春久

  小児歯科学雑誌 一般社団法人 日本小児歯科学会 33 (2) 383 - 383 0583-1199 1995/04/01
• ヒト乳歯歯根の病的異常吸収部位に関する組織学的研究

  八若 保孝, 長内 正数, 谷口 晃一, 小島 寛, 小口 春久

  小児歯科学雑誌 一般社団法人 日本小児歯科学会 33 (2) 319 - 319 0583-1199 1995/04/01
• ELECTRON-MICROSCOPIC AND HISTOCHEMICAL-STUDIES OF THE MONONUCLEAR ODONTOCLAST OF THE HUMAN

  T DOMON, K SUGAYA, Y YAWAKA, M OSANAI, Y HANAIZUMI, S TAKAHASHI, M WAKITA

  ANATOMICAL RECORD 240 (1) 42 - 51 0003-276X 1994/09 [Refereed][Not invited]
   

  Background: Osteoclasts and odontoclasts are multinucleated giant cells which resorb hard tissue by the ruffled borders. Recently, the authors reported the presence of a mononuclear osteoclast with a ruffled border in vitro. However, its presence in vivo has not been shown. To demonstrate the presence of a mononuclear odontoclast in humans, the present study used human deciduous teeth. Methods: After fixation and decalcification, tartrate-resistant acid phosphatase (TRACPase) activity was detected with the azo dye method, and then TRACPase-positive cells were observed on resorbing areas of teeth. TRACPase-positive cells could be distinguished from other cells by light microscopy, and the cells for investigation were serially sectioned by alternating semithin and ultrathin sections to observe their ultrastructure and three-dimensional organization. Results: TRACPase activity was detected in both multinucleated odontoclasts and a mononuclear cell from serial sections. By electron microscopy, most of the multinucleated odontoclasts had ruffled borders and clear zones. A mononuclear TRACPase-positive cell with a ruffled border and clear zone was reconstructed three-dimensionally by NIKON COSMOZONE 2SA. The reconstruction showed that this cell had one irregularly shaped nucleus and a wide ring-shaped clear zone and a small ruffled border. Under the ruffled border, this cell formed a small lacuna on the dentin surface. The results suggested that this cell was a mononuclear odontoclast. Conclusions: The present study concludes that cells with ruffled borders and clear zones observed by transmission electron microscopy can be identified as odontoclasts or osteoclasts irrespective of the number of nuclei.(C) 1994 Wiley-Liss, Inc.
• Observation of odontoclasts in the human deciduous teeth by tartrate-resistant acid phosphatase activity.

  Yawaka Yasutaka

  Journal of Oral Biosciences Japanese Association for Oral Biology 35 (5) 409 - 430 0385-0137 1993 

  The aim of this study is to establish an efficient method for observing the odontoclast whose location has often been difficult to find. To evaluate the feasibility of this method, sequential observations by stereoscopic, light, and transmission electron microscopies were made to detect tartrate-resistant acid phosphatase (TRACPase) activity in the healthy human transitional deciduous teeth.
  The results of the stereoscopic microscopy showed that the positive TRACPase reaction which was presented as a mass of small dots was observed in the regions on the surface of resorbed root and in the pulp chamber wall. Further observations with the light and transmission electron microscopes demonstrated that the major part of the TRACPase-positive region belonged to the resorbing odontoclasts, while the remaining part belonged to the resting odontoclasts and their precursor cells. In conclusion, by using this method, it will be possible to easily localize the exact location of the odontoclast. Furthermore, it can also be expected that this method will facilitate future investigations on odontoclasts.

MISC

• Assessment of the inhibitory effects of glass-ionomer cements containing fluorozincsilicate glass

  鈴木翔斗, 中村光一, 高木康多, 高橋静香, 八若保孝  小児歯科学雑誌  59-  2021
• 日本小児歯科学会主催CBT問題作成ワークショップの実施

  八若 保孝, 内川 喜盛, 香西 克之, 早崎 治明, 飯沼 光生, 清水 武彦, 佐藤 昌史, 藤原 卓, 新谷 誠康, 中村 光一, 高崎 千尋, 木本 茂成  日本歯科医学教育学会総会・学術大会プログラム・抄録集  36回-  151  -151  2017/07  [Not refereed][Not invited]
  
• 日本小児歯科学会主催CBT問題作成ワークショップの実施

  八若保孝, 内川喜盛, 香西克之, 早崎治明, 飯沼光生, 清水武彦, 佐藤昌史, 藤原卓, 新谷誠康, 中村光一, 高橋千尋, 木本茂成  日本歯科医学教育学会総会・学術大会プログラム・抄録集  36th-  151  2017/07  [Not refereed][Not invited]
  
• 小児歯科診療における内在する情動変化の評価方法に関する研究 皮膚電気活動と短時間心拍変動解析の比較

  北村 かおる, 吉原 俊博, 星野 恵, 大島 昇平, 種市 梨紗, 八若 保孝  小児歯科学雑誌  54-  (4)  450  -461  2016/11  [Refereed][Not invited]
   

  心拍変動解析は操作が簡便で侵襲も少なく、また測定精度と時間分解能に優れ、定量化が可能である。そのため自律神経機能の評価法として多く用いられている。歯科診療中の連続した歯科諸刺激に対して自律神経機能を評価するために、直近60秒間の短時間解析データを用いた方法が開発されている。本研究では歯科諸刺激による診療中の小児の情動変化を評価することを目的とし、心電図と皮膚電気活動(Electrodermal activity;以下EDA)を同時に測定した。また、併せて外部行動評価も行った。その結果得られた心拍数(以下HR)とR-R間隔の変動係数(以下CVRR)および心拍変動の短時間解析データから高周波成分(High Frequency>0.15Hz;以下HF)および低周波成分(Low Frequency 0.05〜0.15Hz;以下LF)を分解し、その比であるLF/HFと皮膚電気活動波形の反応様式について比較し、次の結果を得た。1)外部行動評価には表れない小児の情動変化が皮膚電気活動と心拍変動に反映された。2)診療開始前の処置説明時に情動変化があるグループはその後の治療において情動変化を認める場面が多かった。3)心拍変動解析の結果、診療開始前に情動変化があったグループは処置説明時、浸潤麻酔時と抜歯時においてCVRRが安静時よりも有意に高かった。HF、LF、LF/HFにおいては、いずれの処置でも有意差は認められなかった。4)心拍変動解析のCVRRとLF/HFは処置説明時、浸潤麻酔時においてEDAの変動様式と類似した傾向が見られた。以上の結果から、自律神経機能の評価をすることは歯科診療中に内在する情動変化を評価するために有効であることが示唆された。(著者抄録)
• The distribution of number of nuclei of odontoclasts in human deciduous teeth with endodontic treatments

  八木原 澄, 土門 卓文, 八若 保孝  北海道歯学雑誌  36-  (2)  82  -89  2016/03  

  乳歯の生理的歯根吸収は多核巨細胞である破歯細胞によって行われる．過去に著者らはヒト健全乳歯歯根を吸収する破歯細胞の核数を調査し，平均値は5.3，中央値は４であることを報告した．乳歯の歯髄処置後，象牙質に象牙芽細胞は存在せず，根管内にはアルカリ性の水酸化カルシウム製剤が充填されているため，その歯根象牙質は正常象牙質とは異なる構造を持つ．そのため, 歯髄処置経験乳歯における破歯細胞の核数を明らかにすることは，健全乳歯破歯細胞の核数と比較検討し，歯髄処置の与える影響を考える上で重要である．本研究は歯髄処置に 着目し，水酸化カルシウム系根管充填剤であるビタペックス®（ネオ製薬工業，東京）にて歯髄処置後１年から１年10か月経過後に生理的交換期に達したヒト失活乳歯歯根吸収面にみられる破歯細胞の核数の分布を連続切片による観察から検索することを目的とした． 乳歯を抜去後，固定，脱灰，パラフィン包埋後，TRAP活性陽性反応を示す20本の乳歯から乳前歯３本，乳臼歯３本の合計６本の試料を無作為抽出した．試料において４μm厚の連続切片を作製し，TRAP・メチルグリーン染色後，写真撮影を行った．連続切片による観察から歯根象牙質上に吸収窩を形成し，TRAP活性陽性を示す破歯細胞に含まれる核数を計測した．乳前歯99個，乳臼歯101個の破歯細胞の核数について検索した結果，平均値は20.8，中央値は14であった．本研究の結果とヒト健全乳歯の破歯細胞の核数の間には統計学的な有意差が認められた（p＜0.01）．これらの結果は水酸化カルシウム系根管充填剤の存在と歯髄処置による象牙質のpHおよび構造変化が破歯細胞の核数に影響を与えている可能性を示唆している．The root dentine of a human deciduous tooth is physiologically resorbed by multinucleated odontoclasts. Previously, the authors investigated the distribution of the number of nuclei per human odontoclast and showed that the mean number of nuclei per cell is 5.3 and the median is 4. After endodontic treatments of human deciduous teeth, odontoblasts were removed and root canals were filled with the material, alkaline calcium hydroxide. Therefore, the structure of the root dentine after endodontic treatment is different from before treatment. The present study aims to clarify the number of nuclei per odontoclast in human deciduous teeth after endodontic treatments with Vitapex®, a calcium hydroxide-based root canal filling material, and to compare it with that in human deciduous teeth without endodontic treatments. After extraction of deciduous teeth, they were fixed, decalcificated and embedded in paraffin, and six specimens were selected randomly. The specimens were serially sectioned into 4 μm-thick sections and they were stained with TRAP and methyl green, and sections were observed by light microscopy. TRAP-positive cells forming resorptive lacunae on the dentine were identified as odontoclasts, and 99 odontoclasts in anterior teeth and 101 cells in molar ones were investigated to determine the distribution of nuclei per cell. The mean number of nuclei per cell was 20.8 and the median was 14. In the distribution of the number of nuclei per odontoclast, there were statistically significant differences between teeth with endodontic treatments and those without them. These results suggest that the presence of calcium hydroxidebased root canal filling material and root dentine with a different structure may cause change in the number of nuclei of odontoclasts.
• 子どものこころと身体を見守り支援する大規模データ収集とリスク予測モデル構築の試み

  西田佳世, 近藤好夫, 西俣はるか, 今村圭吾, 佐藤恭子, 日高聖, 釜崎陽子, 西口美由季, 星野倫範, 藤原卓, 齋藤幹, 山崎要一, 朝田芳信, 八若保孝, 苅部洋行, 新谷誠康, 早崎治明  小児歯科学雑誌  54-  (1)  155  -155  2016/02/25  [Not refereed][Not invited]
  
• 北海道大学における教育学習支援システム(ELMS)の歯科矯正学実習への応用

  佐藤 嘉晃, 菅原 由紀, 金 壮律, 八若 保孝, 井上 哲, 飯田 俊二, 飯田 順一郎  日本歯科医学教育学会総会・学術大会プログラム・抄録集  34回-  119  -119  2015/07  [Not refereed][Not invited]
  
• Simple and Rapid Conductive Preparation of Wet Biological Samples for SEM Observation: Use of an Asymmetrical Choline-like Room Temperature Ionic Liquid as a Visualizing Agent

  ABE SHIGEAKI, HYONO ATSUSHI, KAWAI KOJI, NAKAMURA KOICHI, YAWAKA YASUTAKA, YOSHIDA YASUHIRO, YONEZAWA TETSU  Nano Biomed  6-  (1)  41  -46  2014/06/30  [Not refereed][Not invited]
  
• セラミックナノ粒子の細胞刺激性の検討

  阿部 薫明, 岩寺 信喜, 半場 悠介, 山方 秀一, 赤坂 司, 八若 保孝, 飯田 順一郎, 亘理 文夫, 古月 文志  日本歯科理工学会誌  33-  (2)  162  -162  2014/03  [Not refereed][Not invited]
  
• 骨芽細胞へと曝露したマイクロ/ナノマテリアルの生体刺激性の検討

  阿部 薫明, 岩寺 信喜, 半場 悠介, 山方 秀一, 赤坂 司, 八若 保孝, 飯田 順一郎, 亘理 文夫  日本歯科理工学会誌  32-  (5)  373  -373  2013/09  [Not refereed][Not invited]
  
• Evaluation on inhibitory effects of decalcification in various sealant materials using pH-cycle system

  USHIMURA Shuya, NAKAMURA Kouichi, YAWAKA Yasutaka  小児歯科学雑誌  51-  (2)  203  -203  2013/04/25
• Trial introduction of rubric for the basics of dental practice in pediatric dentistry

  TAKASAKI Chihiro, CHIDA Natsuko, TANEICHI Risa, NAKAMURA Kouichi, IWADERA Nobuki, ABE Tsugumi, HOSHINO Megumi, USHIMURA Shuya, ENDO Kazuki, OSHIMA Shohei, KIKUIRI Takashi, NOJIMA Yasuko, MINAMIKAWA Hajime, YAMADA Jun-ichi, YAGIHARA Sayaka, YOSHIHARA Toshihiro, YAWAKA Yasutaka  小児歯科学雑誌  51-  (2)  299  -299  2013/04/25  [Not refereed][Not invited]
  
• The effects of forced exercise on fear conditioning and memory

  NOJIMA Yasuko, YAWAKA Yasutaka, FUNAHASHI Makoto  北海道歯学雑誌  33-  (1)  10  -16  2012/09/15  

  本研究は，恐怖学習を獲得させたラットを用い，恐怖記憶に対する強制運動の影響を明らかにすることを目的として行った．SD系雄性ラット（生後4週齢）を用い，すべてのラットに23.5時間の飲水制限下にて，以下の実験群に分けて実験を行った．運動群：4週間の強制運動（回転速度12～15 m/分，60分/日，5日/週で回転ケージ内を歩行）させた群，非運動群：運動はさせず回転ケージ内に10分間入れた後飼育ケージに戻した（4週間）群，において運動スケジュール終了後に恐怖条件付けを行った．恐怖条件付けはオペラントケージを用いて条件刺激をブザー音30秒，無条件刺激を足底への電気刺激（2.5 mA，29秒，5回/5分）として行った．その後恐怖条件付け学習の獲得について評価するために，条件刺激（ブザー音）に対するすくみ行動を解析した．また，運動群と非運動群の精神的不安度に差が無いかを調べるために，高架十字迷路試験を用いて評価を行った．すくみ行動の割合では，運動群の2日目（11.7±3.8％，ｎ＝5）と3日目（0.3±0.3％，ｎ＝5）に対して非運動群では2日目（42.7±5.1％，ｎ＝5），3日目（22.7±7.9％，ｎ＝5）であり，非運動群と比較して運動群のすくみ行動率の有意な低下が認められた．高架十字迷路試験では，運動群と非運動群の間では，全ての項目において有意差は認められなかった．本研究の結果から，強制運動を負荷したことで恐怖記憶が減弱されたことが示された．また，この時運動群と非運動群において精神的不安度に差が無いことも示唆された．以上により強制運動を負荷することで，精神的不安が増強されない程度の恐怖記憶に対してそれを減弱する効果がある可能性が示された．
• エッチング材の違いによるシーラントのヒトエナメル質への微小引張強さ

  王 穎, 角田 晋一, 付 佳楽, 加我 正行, 佐野 英彦, 八若 保孝  特定非営利活動法人日本歯科保存学会学術大会プログラムおよび講演抄録集  136回-  252  -252  2012/05  [Not refereed][Not invited]
  
• 機能性微粒子(S-PRG)含有シーラント材の牛エナメル質接着

  南川 元, 加我 正行, 八若 保孝  小児歯科学雑誌  50-  (2)  214  -214  2012/04/25
• マイクロ・ナノ無機粒子の体内動態と細胞への影響

  岩寺 信喜, 八若 保孝  小児歯科学雑誌  50-  (2)  213  -213  2012/04/25
• 上顎乳臼歯萌出障害の1例

  三浦 真理, 八若 保孝  小児歯科学雑誌  50-  (2)  319  -319  2012/04/25
• 強制運動を行ったラットにおける不快な記憶の減弱について

  野島 靖子, 八若 保孝  小児歯科学雑誌  50-  (2)  295  -295  2012/04/25
• フッ化物作用時におけるフッ化物中に溶出するカルシウム量に関する検討

  中村 光一, 岩寺 信喜, 豊田 有希, 星野 恵, 八若 保孝  小児歯科学雑誌  50-  (2)  209  -209  2012/04/25
• マイクロ/ナノ粒子曝露下の骨芽細胞様細胞と肝細胞の影響

  岩寺 信喜, 阿部 薫明, 石川 紘佑, 赤坂 司, 宇尾 基弘, 八若 保孝, 亘理 文夫  日本歯科理工学会誌  31-  (2)  97  -97  2012/03  [Not refereed][Not invited]
  
• 歯軸異常を伴った埋伏上顎両側中切歯の一例

  谷口 由実, 三浦 真理, 八若 保孝  小児歯科学雑誌  49-  (4)  410  -410  2011/10/25
• 口腔領域の硬組織におけるカルシニューリンの発現

  大島 昇平, 八若 保孝  小児歯科学雑誌  49-  (4)  2011/10/25  [Not refereed][Not invited]
  
• A four-year survey at the clinic of dentistry for children and disabled persons of a university hospital of patients with systemic deseases

  HISADA AKINA  障害者歯科  32-  (3)  243  -243  2011/09/30
• The examination of clinical statistics on dental treatment under general anaesthesia for disabled person of the university hospital about the recently 5-year

  NAKAMURA KOICHI  障害者歯科  32-  (3)  485  -485  2011/09/30
• Trial introduction of rubric for the basics of dental practice in orthodontics

  SATO Yoshiaki, YAMAGATA Shuichi, IWASAKI Hiroshi, KUSAKABE Toyohisa, SUGAWARA KATO Yuki, KIM Takenori, KAJII Takashi, KANEKO Tomoo, YAMAMOTO Takaaki, YOSHIMURA Manabu, YAWAKA Yasutaka, IIDA Junichiro  北海道歯学雑誌  32-  (1)  46  -54  2011/09/15  [Not refereed][Not invited]
   

  北海道大学歯学部の専門教育期に行われる臨床基礎実習のうち，歯科矯正学教室が担当する歯科矯正学臨床基礎実習は舌側弧線装置作製実習と症例分析・診断学実習で構成されている.本実習の目標は「歯科矯正学講義で習得した基礎的，臨床的知識を基に症例分析法・矯正治療，技工技術を身に付けること」である.このようなものは一部パフォーマンス課題と呼ばれるものと考えられるが，従来型の評価法では適正な評価が行われない部分である.昨今，教育カリキェラムがプロセス基盤型からアウトカム基盤型へ移行するに伴い，ポートフォリオなどが徐々に取り入れられており，パフォーマンス系の課題にも対応可能な事が知られている.今回われわれは将来的なポートフォリオ評価の導入も視野に入れることも踏まえ，特にアウトカムに着目したルーブリックを実習にて試行し，有用性を評価することを目的とした.対象は平成21年度の3年次学生(平成22年度の4年次学生)46名とした.これらの学生に対して行われた舌側弧線装置作製実習と症例分析・診断学実習に際して，ルーブリックを用いてアウトカムに対する自己評価をさせた.得られたルーブリックから各項目の平均点を算出し比較した.結果より，両実習ともにプロフェッショナリズムは漸増する傾向がみられ，初回よりも最終回で有意に高かった.さらに，全体に舌側弧線装置作製実習の平均値よりも症例分析・診断学実習のそれが高い傾向を示した.この結果より，将来的なポートフォリオ評価を念頭におくこともふまえ，ルーブリックは歯科矯正学臨床基礎実習の実習に対する応用に有効なツールであることが示唆された.
• Questionnaire survey for using rubric and reflection in the basics of dental practice in orthodontics

  SATO Yoshiaki, IWASAKI Hiroshi, YAMAGATA Shuichi, KUSAKABE Toyohisa, SUGAWARA KATO Yuki, KIM Takenori, KAJII Takashi, KANEKO Tomoo, YAMAMOTO Takaaki, YOSHIMURA Manabu, YAWAKA Yasutaka, IIDA Junichiro  北海道歯学雑誌  32-  (1)  55  -61  2011/09/15  [Not refereed][Not invited]
   

  近年，アウトカム基盤型教育の浸透とともに，ポートフォリオの使用が学習ツールとしても評価としても重要視されている.現在，歯科矯正学臨床基礎実習の4年次前期に行われる症例分析・診断学実習に対しては，将来的なポートフォリオの導入も視野に入れ，「ルーブリック」と「振り返り」を導入している.今回われわれは，この「ルーブリック」と「振り返り」が学習者である学生にとってどの程度の効果があったかを調べるためにアンケートを行った.対象は2010年の4年次学生55名である.これら学生に対して，症例分析・診断学実習における「ルーブリック」および「振り返り」について各々に無記名式のアンケートを行った.アンケート内容はルーブリックや振り返りの効果や実習への反映を問うものである.結果より，「ルーブリック」「振り返り」ともに，学習ツールと しての有効性を認める学生が多かった事，アウトカムの重要性や振り返りを認識できた学生が少なからずいた事，がわかった.一方，「ルーブリック」は日常の学習への反映と言う点ではうまくできていない学生もみられた.これらより，「ルーブリック」「振り返り」の利用は歯科矯正学臨床基礎実習にとって有効である事が示唆された.
• マイクロ・ナノ無機粒子の各種細胞への影響

  岩寺 信喜, 阿部 薫明, 石川 紘佑, 赤坂 司, 宇尾 基弘, 八若 保孝, 亘理 文夫  日本歯科理工学会誌  30-  (5)  318  -318  2011/09
• Tannin-fluoride preparation attenuates prostaglandin E-2 production by dental pulp cells

  Koichi Nakamura, Yoshiaki Deyama, Yoshitaka Yoshimura, Masanor Hashimoto, Masayuki Kaga, Kuniaki Suzuki, Yasutaka Yawaka  MOLECULAR MEDICINE REPORTS  4-  (4)  641  -644  2011/07  [Not refereed][Not invited]
   

  Glass ionomer cements (GICs) are widely used for the operative restoration of dental caries. However, it has been reported that the components of GICs cause pulpal inflammatory responses. Recently, GICs containing tannin-fluoride preparation (HY agent) were developed. In this study, we investigated the effect of HY agent on prostaglandin E, (PGE(2)) release from GIC-stimulated rat dental pulp cells (RPC-C2A). Extracts derived from GIC disks were used with HY(+) and without HY(-) agent. After treatment with GIC extracts, ATP contents, COX-2 mRNA and protein expression in RPC-C2A cells, and PGE(2) production in culture media were analyzed. HY agent suppressed HY(-)-stimulated PGE(2) release from RPC-C2A cells, as well as COX-2 mRNA and protein expression. Moreover, tannic acid attenuated COX-2 mRNA induced by HY(-) extract in a dose-dependent manner. Taken together, these results suggest that tannic acid in MY agent may suppress GIC-induced production of PGE(2) by inhibition of COX-2 expression in dental pulp cells.
• Effect of N-acetylcysteine on Rat Dental Pulp Cells Cultured on Mineral Trioxide Aggregate

  Hajime Minamikawa, Masahiro Yamada, Yoshiaki Deyama, Kuniaki Suzuki, Masayuki Kaga, Yasutaka Yawaka, Takahiro Ogawa  JOURNAL OF ENDODONTICS  37-  (5)  637  -641  2011/05  [Not refereed][Not invited]
   

  Introduction: The purpose of this study was to evaluate the cytotoxicity of mineral trioxide aggregate (MTA) and its potential detoxification by an antioxidant amino acid, N-acetylcysteine (NAC). Methods: Rat dental pulp cells extracted from rat maxillary incisors were directly cultured on MTA with or without NAC in culture medium. The number of cells and their spreading behavior were both assessed 24 hours after seeding. The intracellular levels of reactive oxygen species (ROS) and glutathione (GSH) were also assessed after 24 hours of culture. Results: The number of cells attached to MTA was 60% greater when NAC was added to the culture medium. In addition, the area and perimeter of the cells were found to be 2-fold greater in the culture containing NAC. Cells cultured on MTA alone showed large ROS concentrations, which disappeared when the medium was supplemented with NAC. The intracellular GSH level, however, increased 3.5-fold with NAC addition. Conclusion's: This study demonstrated that the presence of NAC in environments can substantially improve attachment and spreading behaviors of dental pulp cells on MTA. This biological effect was associated with an im-provement in the cellular redox system by NAC and warrants further exploration of NAC for determining its therapeutic value in improving the biocompatibility of MTA. (J Endod 2011;37:637-641)
• Bioreaction Based on Material Nanosizing and Its Application

  WATARI Fumio, YOKOYAMA Atsuro, TOTSUKA Yasunori, KITAGAWA Yoshimasa, YAWAKA Yasutaka, KAWANAMI Masamitsu  日本歯科医学会誌 = Journal of the Japanese Association for Dental Science : JJDS  (30)  30  -34  2011/03/31  [Not refereed][Not invited]
  
• An Impacted Supernumerary Tooth with Backward Movement along the Palate in Maxilla : A Report of Two Cases

  IWADERA Nobuki, TANEICHI Risa, SHINOGUCHI Kyoko, NOJIMA Yasuko, MINAMIKAWA Hajime, YOSHIHARA Toshihiro, YAWAKA Yasutaka  The Japanese Journal of Pediatric Dentistry  49-  (5)  465  -473  2011  [Not refereed][Not invited]
   

  In clinical pediatric dentistry, there are many cases of maxillary impacted supernumerary teeth. We report two rare cases in which an inverted impacted supernumerary tooth moved backward along the palate in the maxilla. Neither inverted impacted supernumerary tooth influenced the dentition or occlusion. CT images showed that each supernumerary tooth had erupted into the nasal mucous membrane. Each supernumerary tooth was surgically extracted. The postoperative course was uneventful,without any symptoms.In conclusion, it is possible to extract an inverted impacted supernumerary tooth without clinical influence by understanding the condition in detail. This case report suggests that CT images are effective for understanding the condition of impacted supernumerary teeth.
• Mechanical Properties and Ions Release of S-PRG Filler-containing Pit and Fissure Sealant

  KAGA Masayuki, MASUTA Junko, HOSHINO Megumi, GENCHOU Michi, MINAMIKAWA Hajime, HASHIMOTO Masanori, YAWAKA Yasutaka  Nano Biomed  3-  (1)  191  -199  2011  [Not refereed][Not invited]
   

  The purpose of this study was to clarify the properties of functional filler-containing pit and fissure sealants (FS). Seventy-two specimens were prepared and divided into three groups of three resin sealants ( S-PRG filler-containing FS, DELTON and Teethmate F1-2.0) and one glass-ionomer sealant (Fuji III LC). Each of six discs (6 mm in diameter ×3 mm in thickness) was used for 24-h, 4-week and 12-week experiments. Diametral tensile strength (DTS) and ion release were measured. S-PRG FS and Delton showed high values of DTS (23.2 MPa and 23.5 MPa, respectively) after 24 hours of storage. The DTS values of each sealant remained relatively constant. A large amount of fluoride was initially released from the sealants. However, fluoride release did not influence on DTS. S-PRG filler-containing FS released large amounts of strontium, boron and fluoride ions. Filler-containing sealants release large amounts of ions, contributing to antibacterial effects.
• An impacted supernumerary tooth with backward movement along the palate in maxilla : a report of two cases.

  IWADERA Nobuki, TANEICHI Risa, SHINOGUCHI Kyoko, NOJIMA Yasuko, MINAMIKAWA Hajime, YOSHIHARA Toshihiro, YAWAKA Yasutaka  The Japanese Journal of Pediatric Dentistry  49-  (5)  465  -473  2011  [Not refereed][Not invited]
   

  In clinical pediatric dentistry, there are many cases of maxillary impacted supernumerary teeth. We report two rare cases in which an inverted impacted supernumerary tooth moved backward along the palate in the maxilla. Neither inverted impacted supernumerary tooth influenced the dentition or occlusion. CT images showed that each supernumerary tooth had erupted into the nasal mucous membrane. Each supernumerary tooth was surgically extracted. The postoperative course was uneventful,without any symptoms.In conclusion, it is possible to extract an inverted impacted supernumerary tooth without clinical influence by understanding the condition in detail. This case report suggests that CT images are effective for understanding the condition of impacted supernumerary teeth.
• 水酸化カルシウム製剤による歯根吸収抑制に関する研究 : 根管内清掃とアルカリ性の拡散

  豊田 有希, 阿部 亜美, 星野 恵, 吉原 俊博, 加我 正行, 八若 保孝  小児歯科学雑誌  48-  (5)  601  -601  2010/11/10
• マイクロ・ナノ粒子の体内循環挙動の追跡と生体への影響

  岩寺 信喜, 石川 紘佑, 伊藤 佐智子, 阿部 薫明, 赤坂 司, 宇尾 基弘, 八若 保孝, 亘理 文夫, 高田 知哉, 米澤 徹  日本バイオマテリアル学会大会予稿集  32回-  323  -323  2010/11  [Not refereed][Not invited]
  
• Properties of micro-filler content sealants

  KAGA M, HASHIMOTO M, ISHIKAWA K, YAWAKA Y  The journal of the Japanese Society for Dental Materials and Devices  29-  (5)  436  -436  2010/09/20  

  Compressive strength and fluoride release of fissure sealants were determined. Specimens of 6mm dia. x 3mm thick disk were light illuminated and immersed in 3ml distilled water. The solution was weekly changed. Fluoride released was measured until 90 days. The disk specimens were (n=6) loaded in compression until failure at 24h, 30th day and 90th day. High amount of fluoride was released from Fuji IIILC. The micro-filler filler content resinous fissure sealants (S-PRG containing sealant and DELTON FS+) released moderate fluoride. Compressive strengths of the fissure sealants demonstrated higher strength than FujiIII LC and Teethmate F-1 2.0.
• マウスに投与したマイクロ・ナノ無機粒子の生体内分布の追跡と細胞への影響

  岩寺 信喜, 阿部 薫明, 石川 紘佑, 赤坂 司, 宇尾 基弘, 大口 郁子, 八若 保孝, 亘理 文夫, 米澤 徹  北海道外科雑誌  55-  (1)  84  -85  2010/06
• 歯科センターおよび病院歯科における障害児(者)歯科診療に関する実態調査

  八若 保孝, 増田 純子, 山田 淳一, 源長 美知, 弘中 祥司, 佐々木 仁弘, 原 昌伸, 梶本 祐一郎, 橋本 敏昭, 朝田 芳信  小児歯科学雑誌  48-  (2)  293  -293  2010/04/25
• PAX9遺伝子変異によって姉弟および母に現れた部分性無歯症の例

  菊入 崇, 関 みゆき, 谷口 由実, 伊藤 佐智子, 福井 亜実, 八若 保孝  小児歯科学雑誌  48-  (2)  254  -254  2010/04/25
• S-PRGフィラー含有新規シーラント材の歯質脱灰抑制効果

  源長 美知, 加我 正行, 増田 純子, 八若 保孝  小児歯科学雑誌  48-  (2)  221  -221  2010/04/25
• ラット歯髄由来細胞におけるグラスアイオノマーセメント浸出液によるPGE_2産生ならびにHY材の作用

  中村 光一, 吉村 善隆, 橋本 正則, 加我 正行, 八若 保孝  小児歯科学雑誌  48-  (2)  280  -280  2010/04/25
• マウス大脳皮質体性感覚野におけるニューロン周囲オリゴデンドロサイトの化学的特性の検討

  高崎 千尋, 大島 昇平, 岡田 理恵子, 八若 保孝  小児歯科学雑誌  48-  (2)  2010/04/25  [Not refereed][Not invited]
  
• Idiopathic osteosclerosis in the mandible associated with abnormal tooth root formation

  Shohei Oshima, Junichi Suzuki, Yasutaka Yawaka  pediatric dental journal  20-  (1)  91  -94  2010  [Not refereed][Not invited]
   

  Idiopathic osteosclerosis (IO) is a localized, well-defined, intra-bony radiopaque lesion within cancellous bone. The causes of IO are still unknown and most lesions are nonexpansile and asymptomatic, so they are often detected incidentally on radiographic examination for other purposes. In the case of jaw lesions, IO is considered to be of no clinical significance and usually requires no treatment. This paper describes two clinical cases about the long-term treatments and observations of mandibular IO in adolescents. The lesions were associated with abnormal tooth root formation and tooth malposition. In these cases, the orthodontic treatments finished successfully without any complication despite the lesions. IO in the jaw needs regular follow-up to ensure normal orofacial development during adolescence. © 2010, The Japanese Society of Pediatric Dentistry. All rights reserved.
• A Survey on the Dental Treatment for the Disable and Medically Compromised Children in Pediatric Dentists in Private Practice : 2. Cooperation and Future Problem

  YAWAKA Yasutaka, TANEICHI Risa, YOSHIHARA Toshihiro, SUZUKI Hiroyuki, KAJIMOTO Yuichiro, HASHIMOTO Toshiaki, SUZUKI Yasuo, IGARASHI Seiji, FUKUTA Osamu, TUCHIYA Tomoyuki, TSUCHIYA Tomoyuki  The Japanese Journal of Pediatric Dentistry  48-  (1)  64  -72  2010  [Not refereed][Not invited]
   

  In order to investigate the actual status of the dental treatment for the disabled patients in private practice, we conducted questionnaire surveys and got answers from 450 specialists out of 1404 specialists in private practice that provided pediatric dentistry (a response rate of 32.1%).As the results, on the dental treatments of disabled children, 90% of the specialists of pediatric dentistry in private practice had the second or the third grade dental institution as an introduced dental hospital. Most of the introduced dental institutions were the university dental hospital. However, the specialists with the cooperation with the educational institutes for disabled children was slight 19.1%. Similarly, the specialists with the cooperation with the administration was 24.4%. Therefore, it was shown that the cooperation between the specialists in private practice and the educational institutes for the disabled children or the administration was insufficient. And it seemed that many problems of time, cost, physical strength and facility such as insurance systems which is not suitable for present state, limit in the practitioner and regional differences existed in the dental treatments of the disabled children by the special practitioners.
• A Survey on the Dental Treatment for the Disable and Medically Compromised Children in Pediatric Dentists in Private Practice : 1. Actual Status

  TANEICHI Risa, YOSHIHARA Toshihiro, SUZUKI Hiroyuki, KAJIMOTO Yuichiro, HASHIMOTO Toshiaki, SUZUKI Yasuo, IGARASHI Seiji, FUKUTA Osamu, TUCHIYA Tomoyuki, YAWAKA Yasutaka, YAWAKA Yasutaka  The Japanese Journal of Pediatric Dentistry  48-  (1)  56  -63  2010  [Not refereed][Not invited]
   

  In order to investigate the actual status of the dental treatment for disabled patients in private practice, we conducted questionnaire surveys and got answers from 450 specialists out of 1404 specialists in private practice that provided pediatric dentistry (a response rate of 32.1%).About half of the respondents (48.7%) had 26−30 years of clinical experience. A ratio of the number of disabled children to all patients in most private practices was 1−5%. A small number of respondents (13.3%) separated the time for the treatment between normal and disabled children. And most of the reasons for visiting the private practice were consisted of the patients or their parents own motive. These results indicated that expert specialists in each area had been performing comprehensive and high-quality treatment for disabled children as well as the normal patients, regardless of the patients age. And it seemed that the specialists in private practice played a role as primary care dentists for the patients. On the other hand, there was great variability related to the age of the respondents in these questionnaire surveys. Therefore, it seemed to be necessary for specialists over generations to share the information for technology and knowledge associated with the dental treatment for disabled children.
• Shear Bond Strength and Fluoride Release and Recharge Performance of Fluoride Releasing Orthodontic Adhesive

  NAKAMURA Koichi, NOMURA Naoko, TOYOTA Yuki, MINAMIKAWA Hajime, KAGA Masayuki, YAWAKA Yasutaka  The Japanese Journal of Pediatric Dentistry  48-  (1)  73  -80  2010  [Not refereed][Not invited]
   

  The purpose of this study was to evaluate the shear bond strengths of fluoride releasing orthodontic adhesive to human enamel. Also, we examined the release of the fluorine of each adhesion materials and recharge performance. As a result, Superbond orthomite is the strongest (16.7 MPa) which deteriorated in order of Fuji ortho LC (14.2 MPa), Krasper F (12.9 MPa), Beauty ortho bond (10.1 MPa),Beauty ortho bond salivatect (7.4 MPa). As for Beauty ortho bond, the enamel surface was smooth as a result of SEM observation after the shear bond strength test. However, the enamel prism structure was exposed in Superbond orthomite and Krasper F which showed strong adhesive strength, and injury to enamel surface. By the measurement of the amount of release of the fluorine and recharge performance, most fluorine released it after one day of the measurement. On the second day, the amount of fluoride release decreased with the third day and became the equilibrium from day 4 to day 7. The most fluoride ions were released from Fuji ortho LC as resin modified glass ionomer cement. Beauty ortho bond which contained S-PRG filler followed it. It had the same tendency after fluoride recharge. Fluoride releasing orthodontic adhesive has moderate adhesive strength with little effect on enamel surface. These had the ability for the release of larger amounts of fluorine and recharge performance, and it was shown that it was effective materials for dental caries during orthodontic treatment.
• Comparison of Enamel Demineralization between Deciduous and Permanent Teeth Using the Automatic pH-cycling System

  SUGAI Makoto, MATSUDA Yasuhiro, NAGAYAMA Masato, KAGA Masayuki, YAWAKA Yasutaka  The Japanese Journal of Pediatric Dentistry  48-  (1)  48  -55  2010  [Not refereed][Not invited]
   

  A forecast of demineralization and remineralization on teeth in the oral cavity is important to prevent and treatment of the occurrence and progression of caries. The automatic pH-cycling system developed by Mastuda et al. can simulate daily changes in pH that occur in the oral cavity. In the previous study, permanent teeth were used to evaluate the caries progression and inhibition. However,there was no study that used deciduous teeth. Therefore, the aim of this study was to compare and evaluate the demineralization on deciduous and permanent tooth enamel using the automatic pHcycling system.A 150-μm thick single-section specimen was prepared from a human extracted deciduous molar and permanent third molar and polished surface was coated with Sticky Wax. The experimented condition was 9 pH cycles/day for four weeks, and a demineralizing solution (lactic acid solution, pH 4.5) and remineralizing solution (HEPES solution, pH 7.0) were used to reproduce the same pH changes that typically occur in the oral cavity. During the interval, the specimen was left in the remineralization solution. The Transverse Microradiography(TMR) images of each specimen were examined to evaluate the progression of artificial caries with respect to integrated mineral loss(IML) and lesion depth(Ld) at week 1, week 2, week 3 and week 4.Integrated mineral loss of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Lesion depth of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Especially, integrated mineral loss and lesion depth of the deciduous tooth at week 4 was higher than that at other weeks.The results suggested that the occurrence and progression of demineralization of the deciduous tooth is higher than the permanent tooth, and we concluded that the automatic pH-cycling system was qualified as a system that evaluated demineralization of the deciduous tooth and the permanent tooth. It could be beneficially employed to clarify the difference of the deciduous tooth and the permanent toothinoralcavity.
• 日本人小児の永久歯先天性欠如に関する疫学的調査

  山崎 要一, 岩崎 智憲, 早崎 治明, 齋藤 一誠, 徳冨 順子, 八若 保孝, 井上 美津子, 朝田 芳信, 田村 康夫, 嘉ノ海 龍三, 牧 憲司, 吉原 俊博, 船津 敬弘, 手島 陽子, 上里 千夏, 山下 一恵, 井出 正道, 栗山 千裕, 近藤 亜子, 嘉藤 幹夫, 渡邉 京子, 藤田 優子, 長谷川 大子, 稲田 絵美, 日本小児歯科学会学術委員会  小児歯科学雑誌  48-  (1)  29  -39  2010  [Not refereed][Not invited]
   

  日本小児歯科学会学術委員会の企画により、わが国初の「永久歯の先天性欠如の発現頻度」に関する全国規模の疫学調査を実施した。国内7大学の付属病院の小児歯科とこれらの大学の調査協力施設に来院した7歳以上の小児15544名(男子7502名、女子8042名)の歯科用エックス線写真を用い、同じ判断基準で調査を行った結果、第3大臼歯を除く永久歯の先天性欠如は1568名(10.09%)に認められた。男女別では男子9.13%、女子10.98%、発現部位別では上顎4.37%、下顎7.58%であり、上顎および下顎における左右差は小さかった。また、歯種別では下顎第二小臼歯が最も多く、次いで下顎側切歯、上顎第二小臼歯、上顎側切歯の順であり、欠如発現者のうち2歯以上の欠如を有する者の頻度は48.3%であった。
• 障がい者歯科医療体制整備事業「北海道障害者歯科医療協力医制度」実地研修『講義』テキスト

  北海道・北海道歯科医師会  2010  [Not refereed][Not invited]
  
• A survey on the dental treatment for the disable and medically compromised children in pediatric dentists in private practice.

  YAWAKA Yasutaka, TANEICHI Risa, YOSHIHARA Toshihiro, SUZUKI Hiroyuki, KAJIMOTO Yuichiro, HASHIMOTO Toshiaki, SUZUKI Yasuo, IGARASHI Seiji, FUKUTA Osamu, TUCHIYA Tomoyuki, TSUCHIYA Tomoyuki  The Japanese Journal of Pediatric Dentistry  48-  (1)  64  -72  2010  [Not refereed][Not invited]
   

  In order to investigate the actual status of the dental treatment for the disabled patients in private practice, we conducted questionnaire surveys and got answers from 450 specialists out of 1404 specialists in private practice that provided pediatric dentistry (a response rate of 32.1%).As the results, on the dental treatments of disabled children, 90% of the specialists of pediatric dentistry in private practice had the second or the third grade dental institution as an introduced dental hospital. Most of the introduced dental institutions were the university dental hospital. However, the specialists with the cooperation with the educational institutes for disabled children was slight 19.1%. Similarly, the specialists with the cooperation with the administration was 24.4%. Therefore, it was shown that the cooperation between the specialists in private practice and the educational institutes for the disabled children or the administration was insufficient. And it seemed that many problems of time, cost, physical strength and facility such as insurance systems which is not suitable for present state, limit in the practitioner and regional differences existed in the dental treatments of the disabled children by the special practitioners.
• A survey on the dental treatment for the disable and medically compromised children in pediatric dentists in private practice.

  TANEICHI Risa, YOSHIHARA Toshihiro, SUZUKI Hiroyuki, KAJIMOTO Yuichiro, HASHIMOTO Toshiaki, SUZUKI Yasuo, IGARASHI Seiji, FUKUTA Osamu, TUCHIYA Tomoyuki, YAWAKA Yasutaka, YAWAKA Yasutaka  The Japanese Journal of Pediatric Dentistry  48-  (1)  56  -63  2010  [Not refereed][Not invited]
   

  In order to investigate the actual status of the dental treatment for disabled patients in private practice, we conducted questionnaire surveys and got answers from 450 specialists out of 1404 specialists in private practice that provided pediatric dentistry (a response rate of 32.1%).About half of the respondents (48.7%) had 26−30 years of clinical experience. A ratio of the number of disabled children to all patients in most private practices was 1−5%. A small number of respondents (13.3%) separated the time for the treatment between normal and disabled children. And most of the reasons for visiting the private practice were consisted of the patients or their parents own motive. These results indicated that expert specialists in each area had been performing comprehensive and high-quality treatment for disabled children as well as the normal patients, regardless of the patients age. And it seemed that the specialists in private practice played a role as primary care dentists for the patients. On the other hand, there was great variability related to the age of the respondents in these questionnaire surveys. Therefore, it seemed to be necessary for specialists over generations to share the information for technology and knowledge associated with the dental treatment for disabled children.
• Comparison of enamel demineralization between deciduous and permanent teeth using the automatic pH-cycling system.

  SUGAI Makoto, MATSUDA Yasuhiro, NAGAYAMA Masato, KAGA Masayuki, YAWAKA Yasutaka  The Japanese Journal of Pediatric Dentistry  48-  (1)  48  -55  2010  [Not refereed][Not invited]
   

  A forecast of demineralization and remineralization on teeth in the oral cavity is important to prevent and treatment of the occurrence and progression of caries. The automatic pH-cycling system developed by Mastuda et al. can simulate daily changes in pH that occur in the oral cavity. In the previous study, permanent teeth were used to evaluate the caries progression and inhibition. However,there was no study that used deciduous teeth. Therefore, the aim of this study was to compare and evaluate the demineralization on deciduous and permanent tooth enamel using the automatic pHcycling system.A 150-μm thick single-section specimen was prepared from a human extracted deciduous molar and permanent third molar and polished surface was coated with Sticky Wax. The experimented condition was 9 pH cycles/day for four weeks, and a demineralizing solution (lactic acid solution, pH 4.5) and remineralizing solution (HEPES solution, pH 7.0) were used to reproduce the same pH changes that typically occur in the oral cavity. During the interval, the specimen was left in the remineralization solution. The Transverse Microradiography(TMR) images of each specimen were examined to evaluate the progression of artificial caries with respect to integrated mineral loss(IML) and lesion depth(Ld) at week 1, week 2, week 3 and week 4.Integrated mineral loss of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Lesion depth of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Especially, integrated mineral loss and lesion depth of the deciduous tooth at week 4 was higher than that at other weeks.The results suggested that the occurrence and progression of demineralization of the deciduous tooth is higher than the permanent tooth, and we concluded that the automatic pH-cycling system was qualified as a system that evaluated demineralization of the deciduous tooth and the permanent tooth. It could be beneficially employed to clarify the difference of the deciduous tooth and the permanent toothinoralcavity.
• Frequency of congenitally missing permanent teeth in Japanese children.

  The Japanese Journal of Pediatric Dentistry  48-  (1)  29  -39  2010  [Not refereed][Not invited]
  
• ナノ粒子の生体反応誘発性 Biointeractive、Bioreactive特性について

  亘理 文夫, 横山 敦郎, 赤坂 司, 宇尾 基弘, 阿部 薫明, 伊藤 佐智子, 大口 郁子, 八若 保孝  日本バイオマテリアル学会大会予稿集  31回-  195  -195  2009/11
• 歯周組織におけるカルシニューリンの発現

  大島 昇平, 高崎 千尋, 八若 保孝  障害者歯科  30-  (3)  2009/09/30  [Not refereed][Not invited]
  
• 無機ケイ酸塩ナノチューブ(イモゴライト)を用いた細胞培養担体の開発

  石川 紘佑, 赤坂 司, 阿部 薫明, 宇尾 基弘, 八若 保孝, 亘理 文夫  歯科材料・器械  28-  (5)  352  -352  2009/09
• カーボンナノチューブ(CNT)に対する肝細胞の挙動

  伊藤 佐智子, 赤坂 司, 八若 保孝, 亘理 文夫  歯科材料・器械  28-  (5)  355  -355  2009/09
• 肝臓細胞の増殖におよぼすカーボンナノチューブの影響について

  伊藤 佐智子, 赤坂 司, 八若 保孝, 亘理 文夫  北海道外科雑誌  54-  (1)  76  -76  2009/06
• Effect of Mineral Trioxide Aggregate on Rat Clonal Dental Pulp Cells: Expression of Cyclooxygenase-2 mRNA and Inflammation-related Protein via Nuclear Factor Kappa B Signaling System

  Hajime Minamikawa, Yoshiaki Deyama, Kouichi Nakamura, Yoshitaka Yoshimura, Masayuki Kaga, Kuniaki Suzuki, Yasutaka Yawaka  JOURNAL OF ENDODONTICS  35-  (6)  843  -846  2009/06  [Not refereed][Not invited]
   

  Introduction: Recently, mineral trioxide aggregate (MTA) has been routinely used for endodontic treatment. It is well-known that MTA induced secondary dentin formation in pulp cavity when it was applied to dentin, whereas its cytotoxicities were unclear. The purpose of this study was to evaluate the effect of MTA on rat clonal dental pulp cells, RPC-C2A. Methods: This study was conducted to observe the response of RPC-C2A cells on MTA with reverse-transcriptase polymerase chain reaction, Western blot analysis, and enzyme immunoassay. Data were compared by analysis of variance. Statistical significance was established at P <.01. Results: MTA significantly caused an up-regulation of cyclooxygenase-2 (COX-2) and inducible form of nitric oxide synthase (iNOS) mRNA expression. Furthermore, MTA caused inhibitory kappa B (I kappa B) phosphorylation and translocation of nuclear factor-kappa B (NF-kappa B) subunits to nucleus. Curucumin, an inhibitor of NF-kappa B activation, suppressed MTA-induced COX-2 and NOS mRNA expressions, In addition, MTA increased the production of prostaglandin E(2) in comparison with the controls. Conclusions: MTA induces inflammation via NF-kappa B signaling system. (J Endod 2009;35:843-846)
• Bone morphogenetic protein-2 down-regulates miR-206 expression by blocking its maturation process

  Mari M. Sato, Masayuki Nashimoto, Takenobu Katagiri, Yasutaka Yawaka, Masato Tamura  BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS  383-  (1)  125  -129  2009/05  [Not refereed][Not invited]
   

  MicroRNAs (miRNAs) are small non-coding RNAs that are emerging as important post-transcriptional gene regulators. miR-206 is unique in that it is expressed only in skeletal muscle, including the myoblastic C2C12 cell line. In C2C12 cells, miR-206 expression was reduced dramatically after bone morphogenetic protein (BMP)-2 treatment. The down-regulation of miR-206 expression was also observed after co-transfection with constitutively-active Smad1 and Smad4, which are the intracellular signaling molecules of the BMP pathway. BMP-2 also reduced miR-206 expression in the presence of alpha-amanitin in a similar manner to that in the absence of alpha-amanitin. Moreover, the expression of pri-miR-206 was increased upon BMP-2 treatment for 6 h compared to that in the absence of BMP-2. These results suggested that BMP-2 down-regulates miR-206 expression at the post-transcriptional level, by inhibiting the processing of pri-miR-206 into mature miR-206, and that BMP-2 Could regulate miRNA biogenesis by a novel mechanism. Crown Copyright (C) 2009 Published by Elsevier Inc. All rights reserved.
• 自動pHサイクル装置を用いた乳歯および永久歯エナメル質脱灰の比較

  須貝 誠, 松田 康裕, 永山 正人, 加我 正行, 八若 保孝  小児歯科学雑誌  47-  (2)  373  -373  2009/04/25
• 乳臼歯が含まれたエナメル上皮腫の1症例

  三浦 真理, 小島 寛, 八若 保孝  小児歯科学雑誌  47-  (2)  279  -279  2009/04/25
• フッ素徐放性矯正ブラケット接着材のヒトエナメル質接着効果

  中村 光一, 豊田 有希, 南川 元, 橋本 正則, 加我 正行, 八若 保孝  小児歯科学雑誌  47-  (2)  226  -226  2009/04/25
• 歯の発育過程におけるカルシニューリンの発現

  大島 昇平, 八若 保孝  小児歯科学雑誌  47-  (2)  2009/04/25  [Not refereed][Not invited]
  
• 骨芽細胞様細胞の成長に及ぼすImogoliteおよびCNTsスキャホールドの影響

  石川 紘佑, 赤坂 司, 鈴木 正哉, 亘理 文夫, 八若 保孝  小児歯科学雑誌  47-  (2)  347  -347  2009/04
• 正常肝細胞と癌肝細胞に対するカーボンナノチューブ(CNT)の影響について

  伊藤 佐智子, 赤坂 司, 亘理 文夫, 八若 保孝  小児歯科学雑誌  47-  (2)  353  -353  2009/04
• 肝臓細胞の増殖に及ぼすCNTの影響

  伊藤 佐智子, 赤坂 司, 八若 保孝, 亘理 文夫  歯科材料・器械  28-  (2)  46  -46  2009/03
• Possible application of flow cytometry for evaluation of the structure and functional status of WASP in peripheral blood mononuclear cells

  Masaru Nakajima, Masafumi Yamada, Koji Yamaguchi, Yukio Sakiyama, Atsushi Oda, David L. Nelson, Yasutaka Yawaka, Tadashi Ariga  EUROPEAN JOURNAL OF HAEMATOLOGY  82-  (3)  223  -230  2009/03  [Not refereed][Not invited]
   

  The Wiskott-Aldrich syndrome protein (WASP), which is defective in Wiskott-Aldrich syndrome (WAS) patients, is an intracellular protein expressed in non-erythroid hematopoietic cells. Previously, we have established methods to detect intracellular WASP expression in peripheral blood mononuclear cells (PBMNCs) using flow cytometric analysis (FCM-WASP) and have revealed that WAS patients showed absent or very low level intracellular WASP expression in lymphocytes and monocytes, while a significant amount of WASP was detected in those of normal individuals. We applied these methods for diagnostic screening of WAS patients and WAS carriers, as well as to the evaluation of mixed chimera in WAS patients who had previously undergone hematopoietic stem cell transplantation. During these procedures, we have noticed that lymphocytes from normal control individuals showed dual positive peaks, while their monocytes invariably showed a single sharp WASP-positive peak. To investigate the basis of the dual positive peaks (WASP(low-bright) and WASP(high-bright)), we characterized the constituent linage lymphocytes of these two WASP-positive populations. As a result, we found each WASP(low/high) population comprised different linage PBMNCs. Furthermore, we propose that the difference between the two WASP-positive peaks did not result from any difference in WASP expression in the cells, but rather from a difference in the structural and functional status of the WASP protein in the cells. It has been shown that WASP may exist in two forms; an activated or inactivated form. Thus, the structural and functional WASP status or configuration could be evaluated by flow cytometric analysis.
• Bone morphogenetic protein-2 enhances Wnt/beta-catenin signaling-induced osteoprotegerin expression

  Mari M. Sato, Aiko Nakashima, Masayuki Nashimoto, Yasutaka Yawaka, Masato Tamura  GENES TO CELLS  14-  (2)  141  -153  2009/02  [Not refereed][Not invited]
   

  Wnt/beta-catenin signaling plays an important role in the developing skeletal system. Our previous studies demonstrated that Wnt/beta-catenin signaling inhibits the ability of bone morphogenetic protein (BMP)-2 to suppress myotube formation in the multipotent mesenchymal cell line C2C12 and that this inhibition is mediated by Id1. In this study, we examined the role of intracellular signaling by Wnt/beta-catenin and BMP-2 in regulating the expression of osteoprotegerin (OPG) and of the receptor activator of NF kappa B ligand (RANKL). OPG expression was induced by Wnt/beta-catenin signaling in C2C12 cells and osteoblastic MC3T3-E1 cells. Silencing of glycogen synthase kinase-3 beta also increased OPG expression. In contrast, R expression was suppressed by Wnt/beta-catenin signaling. In a transfection assay, beta-catenin induced the activity of a reporter gene, a 1.5 kb fragment of the 5'-flanking region of the OPG gene. Deletion and mutation analysis revealed that Wnt/beta-catenin signaling regulates transcription of OPG via a promoter region containing two Wnt/beta-catenin responsive sites. BMP-2 enhanced Wnt/beta-catenin-dependent transcriptional activation of the OPG promoter. In response to BMP-2 stimulation, Smad 1 and 4 interacted with Wnt/beta-catenin responsive sites. These results show that the regulation of OPG expression is mediated through two transcription pathways that involve the OPG promoter.
• 障がい者歯科医療体制整備事業「北海道障害者歯科医療協力医制度」実地研修『講義』テキスト

  北海道・北海道歯科医師会  2009  [Not refereed][Not invited]
  
• Faculty development in Graduate School of Dental Medicine and School of Dental Medicine, Hokkaido University

  八若 保孝, 加我 正行, 飯塚 正, 山本 恒之, 佐藤 嘉晃, 根岸 淳, 北川 善政, 鈴木 邦明, 森田 学, 吉田 重光  Journal of higher education and lifelong learning  (16)  153  -159  2008/12  [Not refereed][Not invited]
   

  Activities of Faculty Development (FD) in the Graduate School of Dental Medicine and School of Dental Medicine of Hokkaido University consist of lectures on FD, workshops on FD and student evaluation of undergraduate lectures. Basically, the lectures on FD are held 4 times every year. The speakers are selected not only from the faculty of Hokkaido University but also from outside the university. A workshop on FD is held once every year. Usually about 30 faculty members of the Graduate School of Dental Medicine participate in the workshop that takes place for two days in a hotel out of campus. The student evaluation of undergraduate lectures is conducted twice every year; i.e., for the lectures in the first semester and the second semester. The lectures and workshop on FD began in 2000, and the student evaluation of undergraduate lectures began in 1997. Many faculty members have participated in the lectures and workshops on FD and made efforts to develop their competence. The student evaluation of undergraduate lectures showed a gain in the score. However, there are a few faculty members who have a negative view of FD in practice.
• 本大学病院小児歯科における最近5年間の障害を有する初診患者の実態調査

  野島 靖子, 岩寺 信喜, 種市 梨紗, 中村 光一, 寺林 えり, 吉原 俊博, 加我 正行, 八若 保孝  障害者歯科  29-  (3)  464  -464  2008/09/30
• The difference of the effect of multi-walled carbon nanotubes on human hepatic normal and cancer cells

  ITOH S., AKASAKA T., YAWAKA Y., WATARI F.  Journal of the Japanese Society for Dental Materials and Devices  27-  (5)  388  -388  2008/09/25
• ケイ酸塩ナノチューブ(イモゴライト)上での骨芽細胞培養

  石川 紘佑, 赤坂 司, 八若 保孝, 亘理 文夫  歯科材料・器械  27-  (5)  433  -433  2008/09
• 小児歯科開業医における障害児歯科診療に関する実態調査 : 2. 連携について 3. 今後の課題について

  八若 保孝, 福田 理, 鈴木 康生, 五十嵐 清治, 梶本 祐一郎, 鈴木 広幸, 橋本 敏昭, 種市 梨紗, 吉原 俊博, 土屋 友幸  小児歯科学雑誌  46-  (2)  241  -241  2008/04/25
• 小児歯科開業医における障害児歯科診療に関する実態調査 : 1. 現状について

  吉原 俊博, 種市 梨紗, 鈴木 広幸, 梶本 祐一郎, 橋本 敏昭, 鈴木 康生, 五十嵐 清治, 福田 理, 土屋 友幸, 八若 保孝  小児歯科学雑誌  46-  (2)  242  -242  2008/04/25
• 鼻腔に近接した上顎正中埋伏過剰歯の状態と対応

  岩寺 信喜, 野島 靖子, 南川 元, 種市 梨紗, 吉原 俊博, 八若 保孝  小児歯科学雑誌  46-  (2)  273  -273  2008/04/25
• グラスアイオノマーセメントのフッ素徐放と機械的強度変化

  南川 元, 塩沢 真帆, 中村 光一, 石川 絋佑, 橋本 正則, 加我 正行, 八若 保孝  小児歯科学雑誌  46-  (2)  229  -229  2008/04/25
• 材料のナノサイジングに基づく生体反応とその応用

  亘理文夫, 横山敦郎, 戸塚靖則, 北川善政, 森田学, 八若保孝, 川浪雅光  日本歯科医学会誌  27-  90  -90  2008/03  [Not refereed][Not invited]
  
• Effect of water on bonding of one-bottle self-etching adhesives

  Masanori Hashimoto, Shinichi Fujita, Masayuki Kaga, Yasutaka Yawaka  DENTAL MATERIALS JOURNAL  27-  (2)  172  -178  2008/03  [Not refereed][Not invited]
   

  This study evaluated the effect of water on dentin substrate bonding of one-bottle self-etching adhesives. Dentin substrates were divided into two groups: wet and dry dentin. Wet dentin is the normal substrate for bond testing whereas dry dentin was dehydrated in a desiccator for 24 hours. Bonded dehydrated teeth were then divided into two subgroups: stored in water or in desiccator for 24 hours. Microtensile bond strength of resin to dentin was measured using three one-bottle self-etching adhesives. In addition, nanoleakage evaluation was performed through the analyses of SEM and TEM micrographs. The bond strength of dry-dentin group was significantly greater than that of wet-dentin. Further, the amount of nanoleakage within the adhesive interface of dry-dentin group was less than that of wet-dentin. Results showed that bond strength and nanoleakage formation depended on the bonding substrate (wet versus dry dentin) before bonding. One-bottle self-etching adhesives might suck the water from dentinal tubules (luring bonding by osmosis, leading to nanoleakage formation and thus a decline in bond strength.
• Wnt/β-cateninとBMP-2シグナルによるOPG遺伝子の発現調節機構の解析

  佐藤 真理, 田村 正人, 八若 保孝  小児歯科学雑誌  46-  (2)  317  -317  2008  [Not refereed][Not invited]
  
• Orthodontic and restorative treatments of an impacted canine in a child with Down syndrome: A case report

  Taneichi Risa, Yoshihara Toshihiro, Oshima Syohei, Yawaka Yasutaka  Ped Dent J  18-  (2)  210  -213  2008  [Not refereed][Not invited]
   

  A 10 year-3 month-old boy with root resorption of the right central incisor associated with impaction of the right canine in the maxilla was referred to our dental clinic by a private general dental practitioner. He had Down syndrome with slight intellectual impairment and no congenital heart disease. Since the results of the mental development age test indicated that his development age was probably more than 4 years and 8 months, we decided that we could treat the patient by using behavior management techniques. We explained the procedures for comprehensive dental treatment in a simplified manner to the patient by using behavior management techniques. The use of enhanced behavior management techniques enabled him to accept comprehensive dental treatment that included extraction of the central incisor and orthodontic and restorative treatments of the impacted canine. We were able to complete the treatments and obtain a good outcome.
• 外傷歯への処置に関する新しい知見

  北海道歯学雑誌  29-  (1)  108  -111  2008  [Not refereed][Not invited]
  
• ラットにおける亜鉛過剰摂取による銅吸収阻害機構

  北海道歯学雑誌  29-  (1)  89  -98  2008  [Not refereed][Not invited]
  
• Repeated immobilization stress in the early postnatal period increases stress response in adult rats

  Toshihiro Yoshihara, Yasutaka Yawaka  PHYSIOLOGY & BEHAVIOR  93-  (1-2)  322  -326  2008/01  [Not refereed][Not invited]
   

  Repeated inunobilization stress tests in the early postnatal period were performed to determine the effects on the growth of developing rats as well as the response of the HPA axis to subsequent novel stress in adulthood. In addition, effects of maternal deprivation (MD) with the same period of the exposure to immobilization stress were also examined. We used 2 different types of immobilization stress and 2 different types of MD: immobilization stress for 30 min/day from postnatal day 7 (P7) to P13 (IS7-13 group); immobilization stress for 30 min on P7 (IS7 group); MD for 30 min/day from P7 to P13 (MD7-13 group); and MD for 30 min on P7 (MD7 group). Body weights were lower in the IS7-13 group than in the control group from P10 to P50, although body weight gain in the MD7-13 group was only transiently affected. Stress-induced corticosterone levels in the IS7-13 group were higher than in the control group and did not return to baseline levels until at least 120 min after the termination of stress, whereas temporal variations of stress-induced corticosterone levels did not differ between the IS, MD7-13, MD7, and control groups. Repeated immobilization stress in the early postnatal period induced long-tern effects on the growth of developing rats and stress response of the HPA axis to the novel stress in adulthood, although a single immobilization stress, periodic MD, or a single MD had little effect. (C) 2007 Elsevier Inc. All rights reserved.
• 障がい者歯科医療体制整備事業「北海道障害者歯科医療協力医制度」実地研修『講義』テキスト

  北海道・北海道歯科医師会  2008  [Not refereed][Not invited]
  
• 上顎中切歯の根吸収を伴う上顎埋伏犬歯の萌出誘導 : Down 症候群児に対する一例

  種市 梨紗, 吉原 俊博, 大島 昇平, 八若 保孝  障害者歯科 = JOURNAL OF THE JAPANESE SOIETY FOR DISABILITY AND ORAL HEALTH  28-  (3)  2007/09/20  [Not refereed][Not invited]
  
• B28 Cell Culture on a Imogolite Scaffold

  Ishikawa Kosuke, Akasaka Tsukasa, Yawaka Yasutaka, Suzuki Masaya, Watari Fumio  粘土科学討論会講演要旨集  (51)  144  -145  2007/09/12
• In vitro durability of one-bottle resin adhesives bonded to dentin

  Masanori Hashimoto, Shinichi Fujita, Masayuki Kaga, Yasutaka Yawaka  DENTAL MATERIALS JOURNAL  26-  (5)  677  -686  2007/09  [Not refereed][Not invited]
   

  Recently, one-bottle resins adhesives have been developed to reduce the number of clinical steps of resin application. They are now widely used in clinical dental practice. However, little is known regarding the detailed mechanism of bond degradation. Therefore, this study evaluated the durability of one-bottle resin adhesives using long-term water storage testing. Resin-dentin bonded specimens were prepared using five commercially available one-bottle resin adhesives. The specimens were sectioned perpendicular to the adhesive interface to produce beams and stored in distilled water for 24 hours (control), 100, 200, and 300 days. After the water storage, each beam was subjected to a microtensile bond test and then SEM fractography was performed on the fractured surface. Compared to the bond strength at 24 hours after bonding (control), the bond strength of all tested adhesives were significantly decreased after 100 or more days in water. SEM fractography revealed a typical type of deterioration in the adhesive-composite interface that might cause a decline in bond strength after aging.
• Flow cytometry を用いたヒト末梢血単核球内WASP分子の構造的, 機能的解析に関する研究

  中島 督, 加我 正行, 八若 保孝  小児歯科学雑誌  45-  (2)  365  -365  2007/05/25
• ヒト乳歯の生理的歯根吸収下における破歯細胞のアポトーシスの免疫組織化学的研究

  谷口 由実, 福井 亜実, 八若 保孝  小児歯科学雑誌  45-  (2)  315  -315  2007/05/25
• グラスアイオノマーセメントのフッ素リチャージ時におけるフッ素浸透深度について

  中村 光一, 加我 正行, 橋本 正則, 八若 保孝  小児歯科学雑誌  45-  (2)  285  -285  2007/05/25
• Dentin Bonding and Bond Durability of One-bottle Adhesive Resins

  FUJITA S., HASHIMOTO M., KAGA M., YAWAKA Y.  Journal of the Japanese Society for Dental Materials and Devices  26-  (2)  93  -93  2007/04/25
• A Seven-year Survey at the Pediatric Dentistry Clinic of a University Hospital of Patients with Systemic Diseases

  YAWAKA Yasutaka, IWABUCHI Hideaki, ITO Sachiko, KAGA Masayuki  小児歯科学雑誌  45-  (5)  623  -631  2007  [Not refereed][Not invited]
  
• ペースト・ペーストタイプの新グラスアイオノマーセメントの歯質接着性とフッ素徐放について．

  加我正行, 岩渕英明, 中村光一, 橋本正則, 八若保孝  小児歯科学雑誌  45-  (1)  81  -87  2007  [Not refereed][Not invited]
  
• Flow cytometryを用いたヒト末梢血単核球内WASP分子の構造的・機能的解析に関する研究

  中島 督, 山田 雅文, 山口 晃司, 崎山 幸雄, 八若 保孝, 有賀 正  北海道歯学雑誌  27-  (2)  190  -200  2006/12  [Not refereed][Not invited]
   

  原発性免疫不全症;Wiskott-Aldrich syndrome(WAS)の原因分子であるWAS protein(WASP)は細胞骨格関連分子として、アクチン重合、シグナル伝達などに関与している。これまでの多くのin vitro研究からWASPはリン酸化、脱リン酸化されること、その結晶構造のモデル解析から分子間結合により自己活性化抑制機能を有することが報告されている。しかしWAS患者が示す多彩な臨床病態とWASP分子の欠損との関連性は必ずしも明確に理解されていない。我々は、ヒト末梢血単核球細胞質内WASP分子をflow cytometryにて解析する系(FCM-WASP)を確立し、WAS患者やその保因者の診断、血液幹細胞移植後の病態解析等に利用してきた。またその過程において正常人単核球ではWASP陽性細胞が強弱二群に分かれることを見出した。本研究では二群が検出される機序の解明を目的とした。その結果、リンパ球サブセットのうちCD56+はWASP強陽性、単球とCD20+は弱陽性、CD4+およびCD8+については強弱両群に属し、さらに検索の結果共にCD45RA+では弱陽性、CD45RO+では強陽性となる傾向を認めた。一方、二群が検出される機序に関して、この現象が抗体の種類によっては再現されないことを検出した。また、純化したCD3+CD45RA+細胞(弱陽性)とCD3+CD45RO+細胞(強陽性)を用いたWASP蛋白レベル、メッセージレベルの比較では明らかな差は認められなかった。さらにin vitroにおける短時間でのリンパ球活性化の系において、活性化の前後でCD8+細胞のFCM-WASPのパターンに明らかな変化を認めた。以上の結果より、FCM-WASPでの強弱陽性両群の違いがWASP分子の量的な違いに基づくものではなく、構造的・機能的違いに基づくものである可能性が示唆された。(著者抄録)
• Wiskott-Aldrich 症候群にみられた歯の形成障害

  三浦 真理, 小島 寛, 及川 透, 八若 保孝  障害者歯科 = JOURNAL OF THE JAPANESE SOIETY FOR DISABILITY AND ORAL HEALTH  27-  (3)  487  -487  2006/09/20
• One-bottle 接着性レジンシステムの吸水性とナノリーケージ

  藤田 慎一, 橋本 正則, 中村 光一, 加我 正行, 八若 保孝  小児歯科学雑誌  44-  (2)  276  -276  2006/04/25
• 接着性レジンが形成誘導する石灰化物

  橋本 正則, 中村 光一, 加我 正行, 八若 保孝  小児歯科学雑誌  44-  (2)  279  -279  2006/04/25
• グラスアイオノマー系充填材料のフッ素リチャージ量とリチャージ時間との相関について

  石川 紘佑, 佐藤 真理, 中村 光一, 橋本 正則, 加我 正行, 八若 保孝  小児歯科学雑誌  44-  (2)  280  -280  2006/04/25
• ヒト乳歯の生理的歯根吸収下における破歯細胞のアポトーシスに関する免疫組織学的研究

  北海道歯学雑誌  27-  (2)  149  -158  2006  [Not refereed][Not invited]
  
• Dentin Bonding of One-bottle Adhesive Resins

  FUJITA Shinichi, HASHIMOTO Masanori, KAGA Masayuki, YAWAKA Yasutaka  小児歯科学雑誌  44-  (4)  556  -566  2006  [Not refereed][Not invited]
  
• 研磨面性状がオールインワン・アドヒーシブの接着強さに及ぼす影響

  吉田 英史, 宇野 滋, 野田坂 佳伸, 加我 正行, 八若 保孝, 平野 進  歯科材料・器械  25-  (1)  47  -53  2006  [Not refereed][Not invited]
   

  オールインワン・アドヒーシブシステムの酸性レジンモノマー溶液は脱灰力が比較的弱いことから,被着面上に生じたスミヤー層の厚さにより接着性が影響されることが危惧される.本研究では,粗さの異なる耐水研磨紙で研磨した象牙質に対する2種オールインワン・アドヒーシブシステム,i BondおよびG-BONDの微小引張接着強さの測定およびSEMによる各材料の脱灰能を観察し,研磨面性状が象牙質との接着に及ぼす影響について検討した.2種オールインワン・アドヒーシブシステムの脱灰能は弱く,微小引張強さは研磨面性状の影響をほとんど受けなかった.研磨面性状が粗い場合,破断面に露出したアドヒーシブレジン層に多数の大きさの異なる空隙が観察された.接着の破断には接着界面に生じた欠陥構造が起因し,i Bondにおいては研磨面性状が象牙質接着強さに影響を及ぼすことが明らかとなった(著者抄録)
• 障がい者歯科医療体制整備事業「北海道障害者歯科医療協力医制度」実地研修『講義』テキスト

  北海道・北海道歯科医師会  2006  [Not refereed][Not invited]
  
• 外傷により下顎頭骨折を生じた小児の咬合変化

  八若 保孝, 岩渕 英明, 黒嶋 玲奈, 谷口 由実, 加我 正行  小児歯科学雑誌  43-  (2)  343  -343  2005/04/25
• 歯科的協力度の向上を通して上顎中切歯の萌出誘導を行った障害児の一例

  障害者歯科  26-  76  -82  2005  [Not refereed][Not invited]
  
• 障害者歯科医療体制整備事業「北海道障害者歯科医療協力医制度」実地研修『講義』テキスト２

  北海道・北海道歯科医師会  2005  [Not refereed][Not invited]
  
• ペースト/ペーストタイプ修復用光硬化型グラスアイオノマーセメントの歯質接着とフッ素徐放について

  加我 正行, 八若 保孝, 岩渕 英明  障害者歯科 = JOURNAL OF THE JAPANESE SOIETY FOR DISABILITY AND ORAL HEALTH  25-  (3)  290  -290  2004/09/30
• 乳歯セメント質の組織学的研究 : 吸収と添加について

  八若 保孝, 福井 亜実, 谷口 由実, 加我 正行, 小口 春久  小児歯科学雑誌  42-  (2)  251  -251  2004/04/25
• Root resorption of human deciduous teeth with apical periodontitis by cultured osteoclasts

  Yasutaka Yawaka, Masakazu Osanai, Youichi Shirai, Tomokazu Hasegawa, Masayuki Kaga, Haruhisa Oguchi  Pediatric Dental Journal  14-  (1)  121  -126  2004  [Not refereed][Not invited]
   

  Roots of human deciduous teeth with apical periodontitis frequently show abnormal resorption as well as cementum deposition, and features that are different from those of physiological root resorption. The aim of this study was to determine the relationship between the appearance of cultured osteoclasts and the condition of dentin slices of human deciduous teeth. Bone marrow obtained from femora of 3- and 4-week-old male C57BL/6 mice was used for cell culture. The cells used in this study were osteoclasts, bone cells and bone marrow cells. Root dentin slices were prepared from human deciduous teeth with apical periodontitis (group 1) and from sound deciduous teeth (group 2, control group). The dentin surfaces were polished with grindstones. Cell suspension in α-MEM supplemented with 10% fetal bovine serum was seeded on the dentin slices and incubated for 96 hours at 37°C under 5% CO2 in air. After incubation, specimens were removed and fixed with glutaraldehyde and paraformaldehyde, and then tartrate-resistant acid phosphatase (TRAP) activity, which is considered to be specific to osteoclasts and odontoclasts, was detected. The number of TRAP-positive cells on the dentin were calculated by light microscopic observation. Specimens were then prepared and observed under a scanning electron microscope (SEM). TRAP-positive cells, visible as small red dots, were observed on dentin slices of both groups (n=50: each group). The densities of TRAP-positive cells in group 1 and group 2 were 2.98±2.57 cells / mm2 and 2.90±2.22 cells/mm2, respectively. The difference between densities of TRAP-positive cells in group 1 and group 2 was not significant by the Mann-Whitney U-test (P> 0.05). Shallow resorbed lacunae were observed on the specimens by scanning electron microscopy. It was shown that root dentin with apical periodontitis was resorbed by clastic cells such as cultured osteoclasts, suggesting that cell growth on dentin is not affected by apical periodontitis. Key words Apical periodontitis, Cultured osteoclasts, Human deciduous teeth, Root resorption, Tartrate-resistant acid phosphatase (TRAP). © 2004, The Japanese Society of Pediatric Dentistry. All rights reserved.
• Changes in occlusal contact area and average bite pressure during treatment of anterior crossbite in primary dentition

  Yasutaka Yawaka, Syouji Hironaka, Akemi Akiyama, Ikuko Matzuduka, Chihiro Takasaki, Haruhisa Oguchi  Journal of Clinical Pediatric Dentistry  28-  (1)  75  -79  2003/09  [Not refereed][Not invited]
   

  The purpose of this study was to examine changes in functional parameters of patients with anterior crossbite in primary dentition during orthodontic treatment. Occlusal contact area (OCA), average bite pressure (ABP) and integrated occlusal load (IOL) were measured. Data obtained before the start of treatment (period A), data obtained when crossbite had improved (period B) and data obtained when the appliance had been removed (period C) were compared. OCA showed the lowest value in period B, and then gradually increased. ABP increased until period B and then declined or became constant. OCA and IOL showed significant differences in periods A and B and periods B and C (p< 0.05). The results suggest that about 6 months is required for stability of the occlusion and acquisition of function in the new occlusion after improvement of crossbite.
• Histological study of deposited cementum in human deciduous teeth with pathological root resorption

  Y Yawaka, M Osanai, A Akiyama, R Ninomiya, H Oguchi  ANNALS OF ANATOMY-ANATOMISCHER ANZEIGER  185-  (4)  335  -341  2003/07  [Not refereed][Not invited]
   

  Physiological root resorption is a characteristic feature of human deciduous teeth. Pathological root resorption due to apical periodontitis, dental trauma or excessive orthodontic force is also observed in deciduous roots. The root resorption is not continuous, and has resting periods. In the resting period, cementum deposits in resorbed root surface. The deposited cementum in permanent teeth has been reported in detail. However, the deposited cementum in deciduous teeth is unclear. The present study examined apices of roots of human deciduous incisors with apical periodontitis and roots of sound deciduous incisors by light and transmission electron microscopy. Root dentin and original cementum had a severe irregular caved surface. Cementum was partially deposited on the caved root surfaces. The deposited cementum had made the caved root surface relatively flat. The cementum was lax and had some defects. The deposited cementum was belt-like in shape and had a stratified structure. Each layer had various structures consisting of abundant microfibrils and fine granular materials, microfibrils, granular materials, and collagen fibrils, a few fibrils and granular materials and a relatively homogeneous structure. The original cementum had many collagen fibrils, such as intrinsic and extrinsic fibers, and no granular materials or homogeneous structure. Therefore, structure of the deposited cementum was very different from that of original cementum in deciduous teeth and from that of deposited cementum in permanent teeth.
• A Five-year Survey of Patients Visiting the Pediatric Dentistry Clinic of a University Dental Hospital for the First Time I. Characteristics of Patients Visiting the Clinic for the First Time

  KIKUCHI Tomoe, YAWAKA Yasutaka, NAKAO Kayoko, HIRONAKA Shouji, KAGA Masayuki, OGUCHI Haruhisa  『小児歯科学雑誌』  41-  (1)  271  -277  2003  [Not refereed][Not invited]
  
• A Five-year Survey of Patients Visiting the Pediatric Dentistry Clinic of a University Dental Hospital for the First Time II. Characteristics of Patients Making Regular Visits to Our Clinic

  NAKAO Kayoko, YAWAKA Yasutaka, KIKUCHI Tomoe, HIRONAKA Shouji, KAGA Masayuki, OGUCHI Haruhisa  『小児歯科学雑誌』  41-  (1)  278  -284  2003  [Not refereed][Not invited]
  
• 溺水後低酸素脳症により大脳に高度の萎縮を認めた症例の嚥下障害の経年変化

  木下 憲治, 阿部 倫子, 八若 保孝, 小口 春久  障害者歯科  23-  (3)  425  -425  2002/09/20
• Delayed eruption of premolars with periodontitis of primary predecessors and a cystic lesion: A case report

  Y. Yawaka, M. Kaga, M. Osanai, A. Fukui, H. Oguchi  International Journal of Paediatric Dentistry  12-  (1)  53  -60  2002/01  [Not refereed][Not invited]
   

  Apical periodontitis after pulp therapy in a primary tooth can cause delayed eruption of the permanent successor. A case of bilateral delayed eruption of mandibular premolars is presented. The patient, a 13-year-old girl, was referred by her dentist. Oral findings showed that the right first and left second primary molars were retained. Other premolars had erupted. An orthopantomogram revealed apical periodontitis, affecting both retained primary molars. The right first mandibular premolar was impacted against the alveolar bone and root of the second premolar, and there was a large cystic lesion in close association with the left second mandibular premolar. Both primary molars were extracted, and the cystic lesion was treated by marsupialization. Fenestration and traction were performed on the right first premolar. Correct tooth alignment was achieved with orthodontic appliances. If the problem had been detected earlier, treatment of the premolars might have been easier. Clinical and radiological follow-up, therefore, of primary teeth that have undergone pulp therapy procedures should be performed until eruption of succedaneous teeth.
• Cystic lesion によって左側下顎第二乳臼歯が偏位した一症例

  加我 正行, 八若 保孝, 小口 春久  小児歯科学雑誌  39-  (2)  404  -404  2001/04/01
• 低カルシウム環境において形成された破骨細胞の形態について

  八若 保孝, 竹山 禎章, 福井 亜実, 吉村 善隆, 小口 春久  小児歯科学雑誌  39-  (2)  358  -358  2001/04/01
• デンタルプレスケールを用いた臼歯部交叉咬合の被蓋改善前後の変化

  松塚 育子, 八若 保孝, 弘中 祥司, 高崎 千尋, 福井 亜実, 小口 春久  小児歯科学雑誌  39-  (2)  302  -302  2001/04/01  [Not refereed][Not invited]
  
• Low calcium environment effects osteoprotegerin ligand/osteoclast differentiation factor

  S Takeyama, Y Yoshimura, Y Shirai, Y Deyama, T Hasegawa, Y Yawaka, T Kikuiri, A Matsumoto, H Fukuda  BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS  276-  (2)  524  -529  2000/09  [Not refereed][Not invited]
   

  In coculture with osteoblastic cell line MC3T3-E1 (El) and mouse bone marrow cells, we reported that numbers of osteoclasts rose significantly on exposure to a low-calcium environment. Here we examined how osteoblasts influence osteoclastogenesis under a low-calcium environment. Comparing low extracellular calcium with a regular calcium environment, osteoprotegerin ligand (OPGL)/osteoclast differentiation factor (ODF) mRNA expression show more increase in the culture of low-calcium environment than in that of a regular calcium environment. Calcium-sensing receptor (CaSR), which was supposed as one of the mechanisms of recognizing extracellular calcium, existed on the surface of El cells. When El cells stimulated with agonists of CaSR, gadolinium, and neomycin, OPGL/ODF mRNA expression decreased. Moreover, these agonists reduced osteoclast formation in coculture. Taken together, it is possible that osteoblasts may recognize extracellular calcium via CaSR and regulate osteoclastogenesis. (C) 2000 Academic Press.
• ヒト乳歯歯根吸収に関する微細形態学的研究 : 歯根吸収面上における破歯細胞の分布

  長内 正数, 土門 卓文, 八若 保孝, 小口 春久  小児歯科学雑誌  38-  (2)  467  -467  2000/04/01
• Ultrastructural study of the root dentine surface resuming resorption on human deciduous teeth

  T Domon, M Osanai, Y Yawaka, R Suzuki, S Takahashi, T Yamamoto, M Wakita  ANNALS OF ANATOMY-ANATOMISCHER ANZEIGER  182-  (2)  175  -184  2000/03  [Not refereed][Not invited]
   

  Resorption of deciduous teeth is not continuous, but alternates with periods of repair or rest. Dentine surfaces in periods of rest or repair resume resorption by odontoclasts during physiological root resorption of the deciduous teeth. However, no observations of such dentine surfaces have been shown. The characteristic feature of the dentine surfaces resuming resorption remains unknown. Tartrate-resistant acid phosphatase activity (TRAP) was detected on human deciduous teeth. The root resorbing surfaces on these teeth were photographed with a whole-mount light microscope, and the photographed areas were serially sectioned into 0.5 mu m semithin sections. Preodontoclasts and odontoclasts were three-dimensionally reconstructed. On root resorbing surfaces, areas with small scattered TRAP-positive cells were observed among areas with many TRAP-positive resorbing odontoclasts and TRAP-negative areas. The sections showed that areas with small scattered TRAP-positive cells have features similar to those of TRAP-negative areas, but there were three kinds of characteristic TRAP-positive cells: preodontoclasts, odontoclasts forming small lacunae, and preodontoclasts and odontoclasts with cytoplasmic processes extending to the dentine surface, which is covered with cells. These results suggest that the areas with small scattered TRAP-positive cells could be at the stage of resuming resorption, and show that the presence of preodontoclasts and odontoclasts with cytoplasmic processes extending to the covered dentine surface is a characteristic feature of the dentine surface at this stage.
• Effect of extracellular calcium concentrations on osteoclast differentiation in vitro

  Y Shirai, Y Yoshimura, Y Yawaka, T Hasegawa, T Kikuiri, S Takeyama, A Matsumoto, H Oguchi  BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS  265-  (2)  484  -488  1999/11  [Not refereed][Not invited]
   

  We have been researching with the purpose of understanding the hard organization mineralization-suppression mechanism under a low calcium environment. So far, we have discerned clearly that the femur of an incubated newborn rat under a low calcium environment will develop bone formation dyscrasia such as hypertrophy of the caput. In this experiment, MC3T3-E1 (El) cells, which are osteoblast-like cells, and mouse bone marrow were incubated in a coculture system under a low calcium environment and manifestation of osteoblast cells and their ability to resorb were examined. The results suggested that as the calcium concentration in the medium decreased manifestation of osteoclast cells increased, and as the degree of mineralization of El cells advanced, the number of manifestation of osteoblast cells decreased. We, therefore, report that there is a possibility that extracellular calcium concentrations involve the process of differentiation of bone marrow cells into osteoblast cells. (C) 1999 Academic Press.
• ヒト破歯細胞の微細形態学的研究歯髄処置経験による相違について

  長内 正数, 土門 卓文, 八若 保孝, 脇田 稔, 小口 春久  歯科基礎医学会雑誌  41-  (5)  461  -461  1999/08/20
• 低カルシウム環境下における破骨細胞発現の組織学的考察

  白井 洋一, 吉村 善隆, 八若 保孝, 長谷川 智一, 竹山 禎章, 松本 章, 小口 春久  小児歯科学雑誌  37-  (2)  321  -321  1999/04/01
• 上顎乳前歯唇側傾斜を目的とした矯正力の後継永久歯に及ぼす影響

  八若 保孝, 秋山 明美, 長内 正数, 弘中 祥司, 原田 理恵, 小口 春久  小児歯科学雑誌  37-  (1)  55  -61  1999/03  [Not refereed][Not invited]
   

  使用した装置は,舌側弧線装置及びチンキャップで,i=SN(上顎の後継永久中切歯切縁からSN平面迄の距離)とi=Occ(上顎の後継永久中切歯切縁から咬合平面迄の距離)を,角度として,SNA,U1-SNと新しく設定したD(後継永久中切歯の傾斜度)を計測した.被蓋改善後において,i=SNの増加,i=Occの減少及びU1-SNの増加が認められた.しかし,SNA,Dにおいては,被蓋改善前後で統計学的有意差は認められなかった.上顎乳前歯部への矯正力が後継永久中切歯の萠出に大きな影響を与えていないことが示唆された
• 第一第二鰓弓症候群の患者にみられた上顎口蓋部の石灰化物について

  原田 理恵, 八若 保孝, 長内 正数, 小口 春久  小児歯科学雑誌  36-  (2)  269  -269  1998/04/01
• 外傷後に歯冠変色をきたした幼若永久前歯の診断法について

  菊入 崇, 白川 哲夫, 加我 正行, 八若 保孝, 小口 春久  小児歯科学雑誌  36-  (2)  367  -367  1998/04/01
• ヒト破歯細胞に関する微細形態学的研究 : 歯髄処置経験の有無による相違について

  長内 正数, 土門 卓文, 八若 保孝, 秋山 明美, 原田 理恵, 小口 春久  小児歯科学雑誌  36-  (2)  303  -303  1998/04/01
• 上顎乳前歯唇側傾斜を目的とした矯正力の後継永久歯に及ぼす影響

  八若 保孝, 秋山 明美, 長内 正数, 弘中 祥司, 原田 理恵, 小口 春久  小児歯科学雑誌  36-  (2)  277  -277  1998/04/01
• 乳前歯反対咬合の被蓋改善前後における咬合接触面積の変化

  弘中 祥司, 八若 保孝, 秋山 明美, 長内 正数, 原田 理恵, 小口 春久  小児歯科学雑誌  36-  (2)  278  -278  1998/04/01
• A Case of Congenital Neurofibroma on the Palatal Region of the Maxillary Anterior Ridge

  AKIYAMA Akemi, YAWAKA Yasutaka, HARADA Rie, OSANAI Masakazu, AMEMIYA Akira, OGUCHI Haruhisa  小児歯誌  36-  (1)  144  -153  1998  [Not refereed][Not invited]
  
• Histological Study of the Exposed Root Apex in the Oral Cavity in Human Deciduous Incisors with Apical Periodontitis

  YAWAKA Yasutaka, OSANAI Masakazu, AKIYAMA Akemi, KOJIMA Hiroshi, OGUCHI Haruhisa  『小児歯科学雑誌』  35-  (5)  812  -820  1997  [Not refereed][Not invited]
  
• Crown Exposure and Traction of Inverted and Unerupted Maxillary Central Incisors with Respect to the Starting Line of Treatment : Three Cases with Different Developmental Stages of the Root

  KOJIMA Hiroshi, MIURA Mari, YAWAKA Yasutaka, OGUCHI Haruhisa  The Japanese Journal of Pediatric Dentistry  34-  (1)  259  -268  1996  [Not refereed][Not invited]
   

  The development of the root subsequent to the crown exposure and traction was clinically evaluated in three cases of inverted and unerupted maxillary central incisors for which the developmental stages of the root were regarded as R 3/4, R 1/2 and R 1/4, respectively at the initiation of the treatment according to the classification of Moorrees et al.
  In the case the treatment procedure was started at R 3/4, the root of the impacted upper central incisor was found to have already bent labially from X-ray exmination before treatment. The development of the root continued in the abnormal direction, so that the solid swelling of the mucous membrane due to the projection of the root apex was recognized after the procedure had been completed.
  In the case the treatment procedure was started at R 1/2, the development of the root continued during the treatment in the same manner as the contralateral tooth with slight bending at the middle portion of the root.
  In the case the treatment procedure was started at R 1/4, the development of the root continued thereafter in the same manner as the contralatelal tooth without root bend.
  These observations indicated that the vitality and activity of the pulp tissue and the root forming tissue was not inhibited during the treatment procedure of inverted and unerupted maxillary central incisors with imcomplete root formation. It was also suggested that the eary treatment at or before the initial stage of root bend in these teeth resulted in successful guidance of eruption avoiding the bent and dwarfed root formation.
• The process of physiological root resorption : Relationship between resorbed root volumes and resorption of coronal pulp chamber wall

  YAWAKA Yasutaka, OSANAI Masakazu, WAKITA Minoru, OGUCHI Haruhisa  Pediatric Dental Journal  6-  (1)  107  -113  1996  [Not refereed][Not invited]
  

Books etc

• 歯科衛生士講座 障害者歯科学 第3版

  八若保孝 (Joint translation第7章 コミュニケーションの確立と行動調整)
  八若保孝 永末書店 2022/02 (ISBN: 9784816014031)
• 小児歯科学ベーシックテキスト第2版

  八若保孝 (Joint work第20章 心身障害児への歯科的対応)
  永末書店 2019/03 (ISBN: 9784816013607)
• 小児歯科学第5版

  八若保孝 (Joint work第7章 小児期の歯・歯周組織の特徴)
  医歯薬出版株式会社 2017/12 (ISBN: 9784263458075)
• スペシャルニーズデンティストリー障害者歯科第2版

  八若保孝 (Joint workⅢ編 スペシャルニーズのある人の歯科医療 Ⅲ予防法 ３－不正咬合)
  医歯薬出版株式会社 2017/02 (ISBN: 9784263458013)
• 小児歯科学 第４版

  医歯薬出版株式会社 2011
• 治療4月増刊号 デキる医師の紹介・逆紹介スキル99

  南山堂 2010
• スペシャルニーズデンティストリー障害者歯科

  医歯薬出版株式会社 2009
• 日本歯科医学教育学会 歯科医学教育白書作成委員会（編），日本歯科医学教育学会雑誌別冊 歯科医学教育白書2005年度版（2003～2005年）

  日本歯科医学教育学会（財：口腔保健協会） 2006
• 乳歯列期における外傷歯の診断と治療<木村光孝，高木裕三，香西克之，朝田芳信（編）>

  クインテッセンス出版 2005
• 乳歯列期における外傷歯の診断と治療<木村光孝，高木裕三，香西克之，朝田芳信（編）>

  クインテッセンス出版 2005
• 乳歯列期における外傷歯の診断と治療<木村光孝，高木裕三，香西克之，朝田芳信（編）>

  クインテッセンス出版 2005

Association Memberships

• 日本接着歯学会   アジア外傷歯学会   日本歯科医学教育学会   日本外傷歯学会   日本小児歯科学会   国際歯科研究学会(International Association for Dental Research)   北海道歯学会   歯科基礎医学会   成育歯科医療研究会   Asian International Association of Dental Traumatology   International Association for Dental Research   

Research Projects

• 生活歯髄切断材料に対する抗酸化アミノ酸の応用~強アルカリによる歯髄刺激からの脱却

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2022/04 -2025/03 

  Author : 中村 光一, 阿部 薫明, 八若 保孝
• Hg・Pb・Al曝露は非認知及び前頭葉機能発達に影響するか？-思春期までの追跡-

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2020/04 -2024/03 

  Author : 草薙 恵美子, 星 信子, 高橋 義信, 中村 光一, 八若 保孝, 森口 佑介, 高橋 文

   

  本研究の目的は、胎児・幼児・学童・思春期の各時期の金属曝露及び家庭環境等が急激な心理的変化の生じる思春期の子どもの心理・脳機能・運動発達に与える影響を縦断的に検討することである。 学童期紙面調査に回答した国内5地域271家庭に母親及び子ども用の調査票を郵送した。母親用調査票では、思春期気質質問紙「EATQ-R(Parent)」日本語版、「日本語版家族機能測定尺度」（FACES Ⅲ）、「子どもの強さと困難さアンケート（SDQ)」（4～17歳用/親記入用）の質問項目、及び食品摂取頻度、家庭の経済状況等について尋ねた。子どもの自記式調査票では、「EATQ-R（Kid）」日本語版、SDQ（11～17歳用/自己記入用）、FACES Ⅲからの質問項目について尋ねた。171名の母親及び167名の子どもから回答を得た。 SDQの子どもの「総合的困難さ」の母親評定値と子どもの自己評定値の相関はr= 0.54であった。重回帰分析により学童期の養育及び気質の思春期「総合的困難さ」への影響を検討した結果、母親による評定では、養育変数と性の調整後、外向性・高潮性（ES）とエフォートフル・コントロール（EC）が困難さを減少させ、否定的情動性（NA）は困難さを増加させることがわかった。子どもの評定した「総合的困難さ」では、ESは有意ではなく、ECの影響度も半減したが、養育尺度の感情的領域が有意となり、子どもの感じる困難さには養育行動が影響していることが確かめられた。 学童期の子どもの毛髪中金属をICP-QQQにより測定した。毛髪処理及び測定の妥当性は標準試料（Human Hair：NIES CRM No.3)を用いて検討した。幼児期で問題のみられたアルミニウムの回収率は、灰化方法を変更することで概ね満足のいく回収率となった。子どもの毛髪中の鉛やマンガン等の金属の含有量は標準試料の毛髪濃度よりも低かった。
• 複雑な乳歯根管系の制御－歯根外部吸収への修復機構の誘導と歯根安定の獲得－

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2020/04 -2023/03 

  Author : 八若 保孝, 中村 光一

   

  根管治療において、根管内壁に生じるスミア層の除去が重要で、根管貼薬剤の効果を根管、根管内壁、象牙細管を通しての根管歯質、歯根外表面へ有効に拡散させることができる。これまでに、根管洗浄として、有機質溶解作用のある次亜塩素酸ナトリウムを使用した超音波洗浄が、乳歯ではスミア層除去に有効であること、永久歯では、硬組織脱灰作用のあるEDTAを使用した超音波洗浄を加えることで、適切なスミア層除去ができることを示すことができた。 適切なスミア層除去により、根管貼薬剤である水酸化カルシウム製剤の効果が歯根外表面にまで拡散することが示され、前述した根管洗浄法が、複雑な乳歯根管系の制御の最も重要な点であることが把握された。 根尖性歯周炎の治療は、炎症のコントロールと病的歯根吸収のコントロールの両面での対応が必要である。根尖性歯周炎は、超音波を用いた根管洗浄により貼薬剤の効果が有効に発揮され、炎症のコントロールの確実性が増加した。歯根吸収においては、前述の有効な根管洗浄により、吸収を示す歯根外表面へ象牙細管を経由した水酸化カルシウムのアルカリ性の拡散が生じる。これにより、酸性環境が必要な歯根吸収部を中和させることができ、歯根吸収抑制の可能性が高くなる。事実、臨床においてこの方法を行うことで、多くの症例で歯根吸収を止めることができた。 歯根外表面の吸収部については、これまでの組織学的検索で、セメント質添加による形態的修復が生じることがあることが報告されている。しかし、どのような環境下で、なにがトリガーとなって、セメント質添加が生じるのかは解明されていない。細胞培養系および実験動物系の2系統を用いて、この点を明らかにする。
• Making pulp capping materials using epigallocatechin-3-gallate

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2019/04 -2022/03 

  Author : Nakamura Koichi

   

  After adding LPS and HEMA stimulation to RAW264.7 cell, and performing WST-8 assay, EGCG did not affect it for cell proliferation. EGCG reduced PGE2 production induced by LPS and HEMA. As the result of pulpotomy, EGCG attenuated recalcification.
• Do mercury and lead exposure effect development of psychological and frontal lobe function?: longitudinal study from early to middle childhood

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2017/04 -2021/03 

  Author : Kusanagi Emiko

   

  We investigated the development of psychological, motor, and brain activities as well as food intake in elementary school children whose hair metal concentrations were measured in early childhood. In addition, the levels of metal exposure during the fetal and infancy periods were determined by measuring the concentration of metals in the deciduous teeth enamel of children using ICP-MS. Early childhood exposure to mercury had an adverse effect on the development of children's temperament in school age. Aluminum and lead had an adverse effect on the development of boys’ fine motor behavior in school age. However, there was no effect of metal exposure on brain function development in school age. We found that the nutritional intake of children was associated with the development of throwing ability and cognitive flexibility. Regarding the factors affecting the amount of metal in hair in early childhood, it was revealed that yogurt intake reduced the exposure levels of lead and aluminum.
• Control of complicated root canal system of primary teeth: Clarification of reliable method for root resorption control and repair mechanism on resorbed part

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2017/04 -2020/03 

  Author : YAWAKA YASUTAKA

   

  Regarding the root canal treatments, it was showed that the important factors of the control of complicated root canal system of primary teeth were the root canal irrigation with ultrasonic and the root canal medication by calcium hydroxide (Ca(OH)2). We constructed a root resorption model in rat molar in animal experiment, and observed histologically the effects of Ca(OH)2 on root resorption. The effects of Ca(OH)2 showed inhibition of root resorption and occurrence of cementum deposition. We think cementum deposition is one of repair mechanisms on resorbed part. We could construct a root resorption model in cell culture. But we do not reach the step as to investigate effects of Ca(OH)2 due to bad reproducibility.
• Control of complicated root canal system of primary teeth: Examination on ion diffusion of calcium hydroxide and effectiveness of outer root resorption control

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2013/04 -2016/03 

  Author : YAWAKA YASUTAKA, NAKAMURA Koichi

   

  Removal of smear layer and opening of dentinal tubules on root canal surface with root canal irrigation is important factor on good convalescence of root canal treatment. Regarding the root canal irrigation, it was showed that combination of EDTA and NaOCl with ultrasonic was effective in removing the smear layer on permanent teeth, and NaOCl with ultrasonic was effective on primary teeth. This study investigated ion diffusion from calcium hydroxide (Ca(OH)2) through the root dentin of extracted human teeth. It was suggested that the smear layer removal and opened dentinal tubules by root canal irrigation with ultrasonic was valid for the alkaline diffusion from Ca(OH)2 to outer root surface. Moreover, it was showed that calcium ion diffused to the outer root surface from root canal. Therefore, it was suggested that the good condition with smear layer removal and opened dentinal tubules by root canal irrigation facilitated the effectiveness of Ca(OH)2 as the root canal medication.
• Collection and Construction of database for physiological and physical support of children

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2012/04 -2016/03 

  Author : FUJIWARA Taku, HOSHINO Tomonori, NISHIGUCHI Miyuki, HIDAKA Kiyoshi, ASADA Yoshinobu, YAMASAKI Youichi, KAMASAKI Youko, MOTOMURA Youichi, SAITOH Kan, KARIBE Hiroyuki, YAWAKA Yasutaka, HAYASAKI Haruaki, SATOH Kyouko, SHINTANI Seikou, HIRATA Souichirou

   

  The purpose of this study is to analyze the data of patients’ background using machine learning method and to develop an application that could output helpful information. We also tried to construct a new system that will enable to continuously collect and utilize these data using tablet. We included data collection system of dental trauma. Data collection system was completed. We will continue data collection using this system. We tried to make decision tree from questionnaire of the mother class using application Weka (Machine Learning Group at the University of Waikato, New Zealand) . Several decision trees were generated, but we could not obtain proper decision trees according with the conventional theory. Since the contents of the sheet were slightly different at each clinic, missing values were likely to influence the analysis. A unified questionnaires style would be necessary. In addition, selection of the objective variable should be more important.
• Control of complicated root canal system of primary teeth: For good results of root canal treatment with apical periodontitis

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2010 -2012 

  Author : YAWAKA Yasutaka

   

  Root canal enlargement and preparation makes the smear layer on the root canal wall. The aim of this study was to evaluate the influence of endodontic irrigation associated with removal of the smear layer. EDTA with ultra sonic or combination of EDTA and NaOCl with ultra sonic was effective in removing the smear layer on permanent teeth. NaOCl with ultra sonic was effective in removing the smear layer on primary teeth. It was suggested that root canal irrigation with ultra sonic was valid for the alkaline diffusion from calcium hydroxide.
• An epidemiological survey about the prevalence of congenitally missing permanent teeth of Japanese children

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2007 -2008 

  Author : YAMASAKI Youichi, IWASAKI Tomonori, HAYASAKI Haruaki, SAITHO Issei, TOKUTOMI Junko, YAWAKA Yasutaka, INOUE Mitsuko, ASADA Yoshinobu, TAMURA Yasuo, KANOMI Ryuzo, MAKI Kenshi, YOSHIHARA Toshihiro, FUNATSU Takahiro, TESHIMA Yoko, UESATO Chika, YAMASHITA Kazue, IDE Masamichi, KURIYAMA Tihiro, MUKAI Ayako, KONDO Tsuguko, KATOH Mikio, WATANABE Kyoko, FUJITA Yuuko, HASEGAWA Hiroko, INADA Emi

   

  北海道大学、昭和大学、鶴見大学、朝日大学、大阪歯科大学、九州歯科大学、鹿児島大学の7大学における附属病院小児歯科と調査協力施設において、エックス線写真を使用した永久歯の先天性欠如に関する疫学調査を行った。対象者は、資料採得時の年齢が永久歯胚の確認が可能となる7歳以上の小児とした。調査対象者総数は15, 544名(男子7, 502名、女子8, 042名)で、永久歯の先天性欠如者数は1, 568名、発現頻度は10.09%であった
• Development of self healing materials with remineralization(Bioglass for dental materials)

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2006 -2007 

  Author : HASHIMOTO Masanori, YAWAKA Yasutaka, KAGA Masayuki, HASHIMOTO Masanori

   

  A finding in this study was that crystal formation (approximately 10 μm in diameter) was a common feature of some fluoridated adhesive resins, where were separated by a standardized interfacial gap between teeth and cured materials. This crystal growth was also found in bioglass (Na_2-CaO-SiO_2-P_2O_5) -containing adhesive resins after several months of water storage. The mechanical properties of resin adhesives are completely reduced by bioglass addition. The decreasing amount of bioglass addition for adhesives prevents a reduction of mechanical property of materials but it reduces an amount of ion releasing for remineralization. The reduction of mechanical property may induced by crystal growth formation due to simultaneous response between bioglass and water. In theory, there are one possibility for increasing the surface area of bioglass per unit, and thus making them more active. An future approach may be simply to decrease glass particle size (nano-sized bioglass), and thus increase the ion exchange surface of glass and surrounding liquid, and prevent mechanical property decreasing for clinical use.
• 遺伝子治療による新しい歯根吸収制御法の開発

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2003 -2003 

  Author : 小口 春久, 吉村 善隆, 八若 保孝, 加我 正行

   

  骨形成・骨吸収の遺伝子治療が考えられている現在、病的あるいは非生理的な「歯根吸収の制御」を遺伝子治療という観点から考えることは、新しい研究分野の展開につながる将来性のある研究の第一歩と考える。破骨細胞は骨吸収を担う多核細胞であり、単球・マクロファージ系細胞の前駆細胞から分化することが知られている。予備実験の結果から、今回我々は、炎症性サイトカインの1つであるマクロファージ遊走阻止因子(MIF)が、破骨細胞分化過程にどのような影響を及ぼすかについて検討を行った。マウス骨芽細胞様細胞(MC3T3-E1細胞)とマウス骨髄細胞との共存培養系によって破骨細胞を誘導し、酒石酸耐性酸性ホスファターゼ(TRAP)活性陽性細胞の出現数、破骨細胞分化因子(RANKL)の発現量、破骨細胞抑制因子(OPG)の産生量および象牙質切片を用いた硬組織吸収能についてMIFの影響を調べた。その結果、TRAP陽性多核細胞の出現数は、MIF濃度に依存して減少することが判明した。一方、MC3T3-E1細胞におけるRANKLの発現およびOPGの産生に、MIFの影響は確認されなかった。TRAP陽性細胞1個中に含まれる核数の分布を調べたところ、MIF作用群ではコントロールと比較し、多核化が抑制されていることが明らかになった。また、象牙質切片上に形成された吸収窩を観察したところ、MIF作用群では形成された吸収窩の大きさが明らかに小さかった。以上の結果より、MIFは骨芽細胞に作用するよりも、むしろ、分化・成熟過程にある破骨細胞の融合過程を阻害することで、成熟した破骨細胞の出現を抑制しているものと考えられ、これらを基盤とすることで、単球・マクロファージ系細胞の破骨細胞前駆細胞もしくは骨髄細胞への遺伝子治療による新しい歯根吸収制御法開発の礎が可能と考えられる。
• Analysis of pathological root resorption of deciduous teeth and establishment for the treatment

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1999 -2001 

  Author : OGUCHI Haruhisa, HASEGAWA Tomokazu, YAWAKA Yasutaka, KAGA Masayuki

   

  SEM observation of root surface of deciduous teeth surface pathologically resorted was done. Exudates from root cannal were analyzed by PCR detection. Moreover, periodontal ligament cells were cultured to study the moleculars concerned with osteoclast differentiation. 1. By SEM observation of deciduous root with severe periodontitis, numerous bacteriums were observed in the root canals or on the root surfaces. However, no bacterium was there in the dentin tubules of apical region. Pathological root resorption was observed in wide region, but there was no odontoclasts. The pathological root resorption was advanced irregularly in the resion and a lot of resorbed lacunae were observed just like a worm-eaten shape. Therefore, it was thought that the pathological root resorption was greatly affected with bacteriums and their products. 2. To determine the bacterial outcome of apical periodontitis in deciduous teeth, Intra-canal exudates were absorbed with sterilized paper points. The suspensions with exudates were analyzed by PCR. The result was that bacterial 16s rDNA was detected in 12 cases out of 16cases tested. Bacterial analysis by PCR is effective to clarify the bacterial species and treatment for periodontitis. 3. Periodontal ligament (PDL) cells produce ten-fold osteoprotegerin (OPG) compared with osteoblasts and gingival cells. It suggests that osteoclast differentiation is depressed by OPG from PDL cells. It appears that PDL is not only connective tissue between a tooth and alveolar bone but also protection of bone and teeth resorption from osteoclast. We think that it is possible to depress for pathological root pesorption with canal root drag containing OPG. These results suggested that complete root canal rinsing and disinfection of root canal are an effective treatment of pathological root resorption. Detection of bacteria species and for the treatment is needed. Moreover, induction of osteoprotegrin was suggested for the new treatment in the apical root inflammation.
• Histological study of pathological root resorption in human deciduous teeth with apical periodontitis.

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1997 -1999 

  Author : YAWAKA Yasutaka, KAGA Masayuki

   

  The purpose of this study was to examine a different root resorption process on the root dentin with apical periodontitis or on sound root dentin. 1. The region of the root apex with severe apical periodontitis in human deciduous teeth was observed by light and transmission electron microscopy. Root dentin and original cementum had a severe irregular caved surface due to pathological root resorption. Cementum had partial!y deposited on the caved dentin and original cementum surfaces. The structure of deposited cementum was very different from that of the original cementum. It was thought that partial repair mechanisms such as cementum deposition are affected by the surrounding environment of the root. 2. Root dentin slices were prepared from human deciduous teeth with apical periodontitis (group p) or sound human deciduous teeth (group n, control). Cell suspension of bone marrow from the femur of mice in α MEM was seeded on the dentin slices and incubated. After incubation, specimens were removed and fixed, and then observed for tartrate-resistant acid phosphatase (TRAP) activity. The number of TRAP-positive cells on the dentin was calculated by light microscopic observation. TRAP-positive cells were observed in all dentin slices. There were no significant differences between group p and group n on the number of TRAP-positive cells by Mann-Whitney test. The results suggested that root dentin with apical periodontitis was resorbed by cultured osteoclasts It was thought that enviromental factors in root circumferences had a greater effect than does the condition of root dentin on pathological root resorption. 3. The root dentin slices of group p and group n were embedded in rats subcutaneous tissue. The dentin slices of both groups were surrounded by fibrous connective tissue are inflammatory cells and partially resorbed by multinuclear giant cells. However, the resorption was slight. There were no differences between the both groups on the condition of the dentin slices. It was thought that the condition of root dentin had few effect on pathological root resorption. Therefore, it was suggested that enviromental factors in root circumferences had a great effect on patholagical root resorption.
• 乳歯列不正咬合に関する形態学的および機能学的研究

  Date (from‐to) : 1992
• The molphological and functional study of malocclusion in primary dentition

  Date (from‐to) : 1992
• 乳歯の生理的歯根吸収および病的異常吸収に関する組織学および分子生物学的研究

  Date (from‐to) : 1989
• Histological and molecular biological study of physiological and pathological root resorption in primary teeth.

  Date (from‐to) : 1989