Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE/OBJECTIVES: Self-assessment is an essential skill for dental professionals. Understanding global trends in self-assessment can highlight the learning needs of students across a diversity of cultural backgrounds. The aim of this study is to compare the self-assessment ability of dental students in the United States and Japan, where cultural backgrounds may differ. METHODS: Students in the United States (n = 176) completed a typodont premolar and anterior Class II and Class III preparation and restoration. Students in Japan (n = 175) completed a typodont premolar crown preparation. Students and faculty then evaluated the student performance using rubrics for each respective procedure. The difference between the student's self-assessment score and the average faculty score (S-F gap) was calculated and the data were analyzed. RESULTS: The mean S-F gap was 2.8% in Japan and 7.6% in the United States. This indicates that Japanese students tended to assess themselves closer to their faculty graders than students in the United States. On average, students in both countries scored themselves higher than their faculty graders. Students in the United States more frequently overestimated their performance and students in Japan more frequently underestimated their performance. For students in the lower quartile, the mean S-F gap was 5.1% in Japan and 14.6% in the United States, indicating a large cultural discrepancy in the lower quartile groups. CONCLUSIONS: Although different preclinical procedures were compared, our findings demonstrated that Japanese students may score themselves more closely to their faculty assessors than students in the United States. Further investigation with more students completing the same preclinical activity will be needed.

DOI： 10.1002/jdd.12779

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

OBJECTIVES: Failed implant removal using a high-frequency electrosurgical device (HFED) has been reported to be less invasive than other surgical techniques. We sought to clarify the mechanism of removal torque reduction in an implant by heating with HFED. MATERIALS AND METHODS: Sixty-eight Wistar rats received titanium implants on the maxillary bone 4 weeks after extraction of the first and second molars. The control group was sacrificed 6 weeks after implant installation. In the experimental group, the implant was heated by HFED for 10 s using three different power outputs, and samples were collected at 3, 7, and 14 days after heating. Removal torque measurement and histological analysis were performed in the control and experimental groups. Implant surfaces were observed using an electron-probe microanalyzer (EPMA). Data were analyzed using Mann-Whitney U test at a significance level of 5%. RESULTS: The removal torque could not be measured in the control group due to fracture of the implant. After heating, the removal torque was measurable without fracture and decreased significantly at 14 days as compared with that at 3 days (p < .05). Heating with "min" power output resulted in a significantly smaller blank lacunae area and fewer osteoclasts at 14 days after heating (p < .05). EPMA revealed bone matrix adherence to outer surface of heated implant. CONCLUSIONS: After heating, an enlarged area of blank lacunae around the implant and an increased number of osteoclasts into the bone marrow cavity were observed, which may have contributed to the reduction in removal torque.

DOI： 10.1111/clr.13793

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Language：Japanese   Publisher：(一社)日本歯科医学教育学会  

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

© 2020, The Author(s). The micro- and nanosize surface topography of dental implants has been shown to affect the growth of surrounding cells. In this study, standardized and controlled periodic nanopatterns were fabricated with nanosized surface roughness on titanium substrates, and their influence on bone marrow stromal cells investigated. Cell proliferation assays revealed that the bare substrate with a 1.7 nm surface roughness has lower hydrophilicity but higher proliferation ability than that with a 0.6 nm surface roughness. Further, with the latter substrate, directional cell growth was observed for line and groove patterns with a width of 100 nm and a height of 50 or 100 nm, but not for those with a height of 10 or 25 nm. With the smooth substrate, time-lapse microscopic analyses showed that more than 80% of the bone marrow cells on the line and groove pattern with a height of 100 nm grew and divided along the lines. As the nanosized grain structure controls the cell proliferation rate and the nanosized line and groove structure (50–100 nm) controls cell migration, division, and growth orientation, these standardized nanosized titanium structures can be used to elucidate the mechanisms by which surface topography regulates tissue responses to biomaterials.

DOI： 10.1038/s41598-020-59395-4

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Language：Japanese   Publisher：新潟歯学会  

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Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science (PLoS)  

DOI： 10.1371/journal.pgen.1008196

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Language：Japanese   Publisher：(公社)日本口腔インプラント学会  

デンタルインプラントにおける術前検査と埋入プロトコルが確立されつつある現在では,その長期予後をいかにして予測し,これを維持するかが新たな課題となっている.長らく歯科界でインプラント適用時の判断基準として使われてきた概念,すなわちインプラント埋入部位の骨量と骨密度を基にした分類は,インプラントの初期固定と骨の力学的支持能力を評価する際に効果的であることは明白である.しかしながら,整形外科領域で診断根拠として用いられる"骨質"は,骨の機械的強度に影響を及ぼす因子の中でも骨密度以外の要素を指し,時に歯科で使われる"骨質"とは全く異なる概念である.整形外科領域で使われる"骨質"の代表的な要素の一つであるコラーゲン架橋は,コラーゲン生合成の過程において細胞内外で生じる一連の翻訳後修飾の結果として形成される分子間架橋であり,その量や構成比が組織の機械的特性に寄与していることが知られている.また,近年の研究から,組織中のコラーゲン架橋は細胞活性を制御することが報告されており,骨組織中のコラーゲン架橋は組織の機械的強度に影響を及ぼすだけでなく,局所的な骨代謝回転を制御する因子としても機能していると考えられる.本総説では骨質の一要素でもあるコラーゲン架橋の新たな機能と,そのインプラント治療における臨床的意義および将来的な展望について紹介する.(著者抄録)

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DOI： 10.3390/dj7020045

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

Bone augmentation therapy is used in dental implantation. While techniques to induce bone formation are generally successful, the maintenance of bone mass is more difficult. Therefore, it is important to understand the mechanisms that regulate this process. Insulin-like growth factor-1 (IGF-1) is one of the most abundant growth factors that regulate bone mass, promote osteoblast differentiation, and accelerate bone formation. The activity of IGF-1 is regulated by IGF-binding proteins (IGFBPs). IGFBP-3 forms a ternary complex with IGF-1, extending its half-life in the circulating system. Therefore, IGFBP-3 acts as a stabilizer and transporter of IGF-1. Recent studies reported new IGF-1-independent functions of IGFBP-3 related with bone metabolism. In this study, we investigated the function of IGFBP-3 in osteoblast differentiation. Our results showed that IGFBP-3 decreases the expression of osteoblast differentiation markers, whose expression is enhanced by bone morphogenetic protein-2 (BMP-2). IGFBP-3 also reduced BMP-2 effect on ALP activity and mineral nodule formation. In addition, IGFBP-3 suppresses the activity of the Smad Binding Element (SBE) reporter, induced by BMP-2 signaling. These results suggest that IGFBP-3 inhibits osteoblast differentiation through the BMP-2 signal pathway, and that IGFBP-3 might play a role in bone mass maintenance in an IGF-1-dependent and -independent manner.

DOI： 10.1016/j.bbrc.2018.11.065

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© 2018, Japanese Society for Oral and Maxillofacial Radiology and Springer Nature Singapore Pte Ltd. Dental cone-beam computed tomography (CBCT) received regulatory approval in Japan in 2000 and has been widely used since being approved for coverage by the National Health Insurance system in 2012. This imaging technique allows dental practitioners to observe and diagnose lesions in the dental hard tissue in three dimensions (3D). When performing routine radiography, the examination must be justified, and optimal protection should be provided according to the ALARA (as low as reasonably achievable) principles laid down by the International Commission on Radiological Protection. Dental CBCT should be performed in such a way that the radiation exposure is minimized and the benefits to the patient are maximized. There is a growing demand for widespread access to cutting-edge health care through Japan’s universal health insurance system. However, at the same time, people want our limited human, material, and financial resources to be used efficiently while providing safe health care at the least possible cost to society. Japan’s aging population is expected to reach a peak in 2025, when most of the baby boomer generation will be aged 75 years or older. Comprehensive health care networks are needed to overcome these challenges. Against this background, we hope that this text will contribute to the nation’s oral health by encouraging efficient use of dental CBCT.

DOI： 10.1007/s11282-018-0314-3

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DOI： 10.1371/journal.pone.0204306

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Cyclophilin B (CypB) is an endoplasmic reticulum-resident protein that regulates collagen folding, and also contributes to prolyl 3-hydroxylation (P3H) and lysine (Lys) hydroxylation of collagen. In this study, we characterized dentin type I collagen in CypB null (KO) mice, a model of recessive osteogenesis imperfecta type IX, and compared to those of wild-type (WT) and heterozygous (Het) mice. Mass spectrometric analysis demonstrated that the extent of P3H in KO collagen was significantly diminished compared to WT/Het. Lys hydroxylation in KO was significantly diminished at the helical cross-linking sites, alpha 1/alpha 2(I) Lys-87 and alpha 1(I) Lys-930, leading to a significant increase in the under-hydroxylated cross-links and a decrease in fully hydroxylated cross-links. The extent of glycosylation of hydroxylysine residues was, except alpha 1(I) Lys-87, generally higher in KO than WT/Het. Some of these molecular phenotypes were distinct from other KO tissues reported previously, indicating the dentin-specific control mechanism through CypB. Histological analysis revealed that the width of predentin was greater and irregular, and collagen fibrils were sparse and significantly smaller in KO than WT/Het. These results indicate a critical role of CypB in dentin matrix formation, suggesting a possible association between recessive osteogenesis imperfecta and dentin defects that have not been clinically detected.

DOI： 10.1021/acs.jproteome.7b00190

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Language：Japanese   Publisher：(一社)日本歯科医学教育学会  

本邦では、社会の急速な高齢化に伴い、高度な治療が求められる患者や全身的な疾患を有する患者が増加している。また、患者の意識変化によって、より質の高い治療を求められることが多くなっている結果、臨床実習に協力していただける患者が減少している。このような背景から、学生は限られた患者を対象に臨床技能の習得をし、卒業時には相応の知識と臨床能力を確保しなければならない。この問題を解決するための手段として、新潟大学歯学部では1つの模型の中に様々な病態を具備した6種類のオリジナルの模型を開発し、治療計画立案を含めた統合的な模型実習を導入している。実習は臨床実習直前の5年前期に実施され、基礎模型実習と臨床実習をつなぐと共に、不足する臨床実習を補完する役割を果たす。模型には歯石除去必要部位、抜歯、充填、歯内治療、分割抜歯適応歯および歯冠修復、不良補綴歯、欠損補綴適応部位を含む。学生は診断・治療計画立案から歯科処置までをファントムに装着した模型上で実際の臨床をシミュレートする形で行う。現在、本実習の評価はルーブリックを用いて行っているが、評価方法に関しては今後も継続的に検討する必要がある。実習後の学生アンケートからは実習が有意義なものであったとの回答を得ており、知識や技術を使いこなす統合的な能力の育成に有効であることが示唆された。(著者抄録)

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2017&ichushi_jid=J02148&link_issn=&doc_id=20170904280005&doc_link_id=10.24744%2Fjdea.33.2_106&url=https%3A%2F%2Fdoi.org%2F10.24744%2Fjdea.33.2_106&type=J-STAGE&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00007_3.gif

DOI： 10.1177/0022034515616760.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

Covalent intermolecular cross-linking provides collagen fibrils with stability. The cross-linking chemistry is tissue-specific and determined primarily by the state of lysine hydroxylation at specific sites. A recent study on cyclophilin B (CypB) null mice, a model of recessive osteogenesis imperfecta, demonstrated that lysine hydroxylation at the helical cross-linking site of bone type I collagen was diminished in these animals (Cabral, W. A., Perdivara, I., Weis, M., Terajima, M., Blissett, A. R., Chang, W., Perosky, J. E., Makareeva, E. N., Mertz, E. L., Leikin, S., Tomer, K. B., Kozloff, K. M., Eyre, D. R., Yamauchi, M., and Marini, J. C. (2014) PLoS Genet. 10, e1004465). However, the extent of decrease appears to be tissue-and molecular site-specific, the mechanism of which is unknown. Here we report that although CypB deficiency resulted in lower lysine hydroxylation in the helical cross-linking sites, it was increased in the telopeptide cross-linking sites in tendon type I collagen. This resulted in a decrease in the lysine aldehyde-derived cross-links but generation of hydroxylysine aldehyde-derived cross-links. The latter were absent from the wild type and heterozygous mice. Glycosylation of hydroxylysine residues was moderately increased in the CypB null tendon. Wefound that CypB interacted with all lysyl hydroxylase isoforms (isoforms 1-3) and a putative lysyl hydroxylase-2 chaperone, 65-kDa FK506-binding protein. Tendon collagen in CypB null mice showed severe size and organizational abnormalities. The data indicate that CypB modulates collagen cross-linking by differentially affecting lysine hydroxylation in a site-specific manner, possibly via its interaction with lysyl hydroxylases and associated molecules. This study underscores the critical importance of collagen post-translational modifications in connective tissue formation.

DOI： 10.1074/jbc.M115.699470

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Surface topography broadly influences cellular responses. Adherent cell activities are regulated, in part, by RhoA, a member of the Rho-family of GTPases. In this study, we evaluated the influence of surface topography on RhoA activity and associated cellular functions. The murine mesenchymal stem cell line C3H10T1/2 cells (osteoprogenitor cells) were cultured on titanium substrates with smooth topography (S), microtopography (M), and nanotopography (N) to evaluate the effect of surface topography on RhoA-mediated functions (cell spreading, adhesion, migration, and osteogenic differentiation). The influence of RhoA activity in the context of surface topography was also elucidated using RhoA pharmacologic inhibitor. Following adhesion, M and N adherent cells developed multiple projections, while S adherent cells had flattened and widespread morphology. RhoA inhibitor induced remarkable longer and thinner cytoplasmic projections on all surfaces. Cell adhesion and osteogenic differentiation was topography dependent with S&lt;M and N surfaces. RhoA inhibition increased adhesion on S and M surfaces, but not N surfaces. Cell migration in a wound healing assay was greater on S versus M versus N surfaces and RhoA inhibitor increased S adherent cell migration, but not N adherent cell migration. RhoA inhibitor enhanced osteogenic differentiation in S adherent cells, but not M or N adherent cells. RhoA activity was surface topography roughness dependent (S&lt;M, N). RhoA activity and -mediated functions are influenced by surface topography. Smooth surface adherent cells appear highly sensitive to RhoA function, while nano-scale topography adherent cell may utilize alternative cellular signaling pathway(s) to influence adherent cellular functions regardless of RhoA activity. J. Cell. Physiol. 231: 568-575, 2016. (c) 2015 Wiley Periodicals, Inc.

DOI： 10.1002/jcp.25100

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DOI： 10.1097/ID.0000000000000369

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Topographies promote surface-dependent behaviors which may positively influence peri-implant bone healing. In this study the topological effects of TiO2 nanotubes (TNTs) on aspects of preosteoblast behavior was investigated. Specifically, we hypothesize that TNTs can influence the cell proliferation of preosteoblasts through cell adhesion and related modulation of FAK and RhoA. By culturing MC3T3-E1 cells on TNTs with different diameters (40 nm and 150 nm diameters), topography-dependent modulation in cell morphology and cell growth were observed. The average spreading area of the cell on flat Ti, 40 nm TNTs and 150 nm TNTs were respectively 2176.05 mu m(2), 1510.44 mu m(2) and 800.72 mu m(2). Proliferation increased among cells cultured on the 150 nm TNTs (28.6%) compared with on flat Ti (17.06%). The expression of FAK was 86.2% down regulated with the superimposition of the TNT topography. RhoA expression only slightly decreased (45.9%). Increasing the TNT diameter enhanced the initial adherent cell growth, which was relevant to the increased RhoA-to-FAK ratio in the cell. Increased TNT diameter was associated with a higher ratio and greater proliferation in the first 24 hours. These findings not only support our hypothesis, but suggest that RhoA might be critically involved in TNTs mediated cell proliferation. Future investigation using functional gain and loss of RhoA may further reveal its mechanism.

DOI： 10.1039/c4ra16803h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Topographies promote surface-dependent behaviors which may positively influence peri-implant bone healing. In this study the topological effects of TiO2 nanotubes (TNTs) on aspects of preosteoblast behavior was investigated. Specifically, we hypothesize that TNTs can influence the cell proliferation of preosteoblasts through cell adhesion and related modulation of FAK and RhoA. By culturing MC3T3-E1 cells on TNTs with different diameters (40 nm and 150 nm diameters), topography-dependent modulation in cell morphology and cell growth were observed. The average spreading area of the cell on flat Ti, 40 nm TNTs and 150 nm TNTs were respectively 2176.05 mu m(2), 1510.44 mu m(2) and 800.72 mu m(2). Proliferation increased among cells cultured on the 150 nm TNTs (28.6%) compared with on flat Ti (17.06%). The expression of FAK was 86.2% down regulated with the superimposition of the TNT topography. RhoA expression only slightly decreased (45.9%). Increasing the TNT diameter enhanced the initial adherent cell growth, which was relevant to the increased RhoA-to-FAK ratio in the cell. Increased TNT diameter was associated with a higher ratio and greater proliferation in the first 24 hours. These findings not only support our hypothesis, but suggest that RhoA might be critically involved in TNTs mediated cell proliferation. Future investigation using functional gain and loss of RhoA may further reveal its mechanism.

DOI： 10.1039/c4ra16803h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：QUINTESSENCE PUBLISHING CO INC  

Purpose: Although the recent success rates of dental implants are quite high, it is still true that loading during the bone healing period may be more likely to discourage osseointegration and that occlusal overloading might result in implant failure, even after osseointegration is established. The purposes of this study were to establish an appropriate experimental animal model and to histologically assess degenerative changes in established osseointegration under early and excessive occlusal loading. Materials and Methods: Forty rats were divided into control and experimental groups. The maxillary first and second molars on both sides were extracted, and machined-surface titanium implants were placed. In the experimental group, 2 or 4 weeks after implant placement, abutments that were designed to overload the implants were attached. Control group implants did not receive abutments and remained in situ 2 or 4 weeks. Sections were prepared and observed histologically. Results: Attrition of occluding opposite teeth and shiny spots on the abutments indicated that this model was useful for histologic investigation of the remodeling and bone changes around implants. Specimens showed remarkable bone loss and deterioration of osseointegration when overloading began at 2 weeks. Overloading applied after 4 weeks of healing induced active bone resorption in remote areas of the implants after 15 days of occlusion, while bone resorption at the interface was limited. Conclusion: The authors successfully established an implant occlusion model using rats. This model revealed degenerative changes in osseointegration and/or in the bone around implants upon excessive occlusal loading. These results emphasize the risks associated with immediate loading and overloading. This is the first study to reveal the possibility of bone loss around overloaded implants in the absence of infection using a small animal model.

DOI： 10.11607/jomi.2388

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Language：Japanese   Publisher：新潟歯学会  

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Other Link： http://search.jamas.or.jp/link/ui/2008317081

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Language：Japanese   Publisher：日本歯科医学会  

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Language：Japanese   Publisher：(株)北隆館  

歯科に用いられている各種合金が金属アレルギーの原因となり得ることが知られている。ところが、臨床的にはその存在がほぼ確実であるにもかかわらず、基礎研究や臨床研究の遅れにより、明確な診断・治療方法は見出されていない。歯科金属アレルギーはそのほとんどが全身性接触皮膚炎として病態を現す。今後は病態と金属の種類ごとにその発症メカニズムを解明し、診断・治療に資する成果が求められている。本稿ではその歴史、実態、代表的症状と現状での問題点を概説し、歯科金属アレルギーに関する理解を深める一助としたい。(著者抄録)

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Language：English   Publisher：(公社)日本補綴歯科学会  

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Event date： 2021.3

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