Jun Takebe

The effect on immunocytes of anodic oxide titanium after hydrothermal treatment.

All dental root implants come in contact with the oral epithelium, and many complex factors are found to arise in this region. In order to perform a successful dental root implantation, it is necessary to clarify the interaction of the dental root implant material with the host defense mechanisms involved in the specific and nonspecific immune responses to many antigens in oral bacteria and their components. Recently, focusing on developing the dental root implant, the Nikon Corporation improved the surface characteristics of pure titanium even further by developing a hydroxyapatite (HA) layer formed on an anodic titanium oxide film containing Ca and P via hydrothermal treatment (SA treatment). However, since little is known about the effect of SA-treated pure titanium (HA/Ti) on the defense mechanisms of the oral membrane epithelium, we investigated (1) the in vitro proliferation of murine splenic B lymphocytes on the surface of HA/Ti in the presence of three lipopolysaccharide (LPS) concentrations and (2) interleukin-1alpha (IL-1alpha) production by the reaction of human peripheral blood mononuclear cells (PBM cells) on the surface of HA/Ti under the same concentrations. After culture, murine splenic lymphocytes were measured by uptake of 3H-thymidine, and cytokine release (IL-1alpha) from PBM cells was measured by ELISA. Results showed that HA/Ti had hardly any effect on the LPS-induced proliferation of B lymphocytes and IL-1alpha production. In vitro investigations of the effects of HA/Ti on the LPS-induced proliferation of murine splenic B lymphocytes and IL-1alpha from PBM cells might be a useful way of elucidating the defense mechanism between implants and the oral epithelium.

Biological behavior of fibroblast-like cells cultured on anodized-hydrothermally treated titanium with a nanotopographic surface structure

PURPOSE The interface between the transmucosal portion of endosseous implants surface and the connective tissue is characterized by fibroblast-rich barrier tissue, which is important for the long-term stability and maintenance of the implant. This study investigated the effect of cell adhesion on focal adhesion kinase (FAK) protein and on gene expression over a 72-h culture period. Fibroblast-like cells were cultured on anodized-hydrothermally treated commercially pure titanium with nanotopographic structure (SA-treated c.p.Ti) surfaces. METHODS Murine fibroblast-like NIH/3T3 cells were cultured for 10-72h on c.p.Ti, anodic oxide (AO) c.p.Ti, and SA-treated c.p.Ti disks. Cell morphology was analyzed using scanning electron microscopy (SEM). Cytoskeletal structure and FAK protein localization were analyzed using confocal laser scanning microscopy (CLSM). FAK mRNA levels were analyzed using real-time quantitative RT-PCR. RESULTS SEM and CLSM showed increased NIH/3T3 cell adhesion with time, and actin filaments oriented parallel with the filopodium-like extensions on all disks. Filopodium-like extensions were bound tightly to the nanotopographic structure surface of cultures on SA-treated c.p.Ti, and especially at 72h. FAK protein was localized along cellular extensions on SA-treated c.p.Ti and the expression of FAK mRNA was significantly higher on these disks than on c.p.Ti and AO c.p.Ti after 72h (P<0.05). CONCLUSIONS NIH/3T3 fibroblast-like cells have the capacity to adhere to SA-treated c.p.Ti as a transmucosal portion of implant surface material and express focal adhesion molecules, which may play a key role in the maintenance of a mucosal tissue barrier.

Physicochemical state of the nanotopographic surface of commercially pure titanium following anodization-hydrothermal treatment reveals significantly improved hydrophilicity and surface energy profiles

A method of coating commercially pure titanium (cpTi) implants with a highly crystalline, thin hydroxyapatite (HA) layer using discharge anodic oxidation followed by hydrothermal treatment (Spark discharged Anodic oxidation treatment ; SA-treated cpTi) has been reported for use in clinical dentistry. We hypothesized that a thin HA layer with high crystallinity and nanostructured anodic titanium oxide film on such SA-treated cpTi implant surfaces might be a crucial function of their surface-specific potential energy. To test this, we analyzed anodic oxide (AO) cpTi and SA-treated cpTi disks by SEM and AFM. Contact angles and surface free energy of each disk surface was measured using FAMAS software. High-magnification SEM and AFM revealed the nanotopographic structure of the anodic titanium oxide film on SA-treated cpTi; however, this was not observed on the AO cpTi surface. The contact angle and surface free energy measurements were also significantly different between AO cpTi and SA-treated cpTi surfaces (Tukeys, P<0.05). These data indicated that the change of physicochemical properties of an anodic titanium oxide film with HA crystals on an SA-treated cpTi surface may play a key role in the phenomenon of osteoconduction during the process of osseointegration.

Transplantation of dental pulp stem cells suppressed inflammation in sciatic nerves by promoting macrophage polarization towards anti-inflammation phenotypes and ameliorated diabetic polyneuropathy.

Dental pulp stem cells (DPSCs) are thought to be an attractive candidate for cell therapy. We recently reported that the transplantation of DPSCs increased nerve conduction velocity and nerve blood flow in diabetic rats. In the present study, we investigated the immunomodulatory effects of DPSC transplantation on diabetic peripheral nerves.

Anodized-hydrothermally treated titanium with a nanotopographic surface structure regulates integrin-α6β4 and laminin-5 gene expression in adherent murine gingival epithelial cells

PURPOSE Peri-implant epithelium associated with the structure of the internal basal lamina is in contact with a transmucosal portion of the endosseous implant surface. This contact is important to protect the many complex factors required for the long-term stability and maintenance of the implant. This study investigated the effect of initial adhesion of gingival epithelial cells to anodized-hydrothermally treated commercially pure titanium with nanotopographic structure (SA-treated c.p.Ti). Changes in cell morphology and gene expression of integrin-α6β4 and laminin-5 were assessed. METHODS Murine immortalized gingival epithelial (GE1) cells were cultured for 1-3 days on c.p.Ti, anodic oxide (AO) c.p.Ti, and SA-treated c.p.Ti disks. Cell morphology was analyzed using scanning electron microscopy (SEM). Cell proliferation was analyzed using the WST-1 assay. Integrin-α6β4 and laminin-5 (α3, β3, γ2) mRNA levels were measured using real-time quantitative RT-PCR. RESULTS The GE1 cells appeared flattened with extensions on all disks by SEM analysis. Filopodium-like extensions were bound closely to the nanotopographic structure surface of SA-treated c.p.Ti especially at day 3 of culture. GE1 cell proliferation as well as the expression of integrin-α6β4 and laminin-5 (α3, β3, γ2) mRNAs was significantly higher on SA-treated c.p.Ti than on c.p.Ti and AO c.p.Ti disks after 3 days (P<0.05). CONCLUSIONS Gingival epithelial cells initially attach to a transmucosal portion of SA-treated c.p.Ti implant material and subsequently express the integrin-α6β4 adhesion molecule and the laminin-5 extracellular matrix molecule. This cell behavior may play a key role in maintaining the peri-implant oral mucosal tissue barrier.

Three CoA Transferases Involved in the Production of Short Chain Fatty Acids in Porphyromonas gingivalis.

Butyryl-CoA:acetate CoA transferase, which produces butyrate and acetyl-CoA from butyryl-CoA and acetate, is responsible for the final step of butyrate production in bacteria. This study demonstrates that in the periodontopathogenic bacterium Porphyromonas gingivalis this reaction is not catalyzed by PGN_1171, previously annotated as butyryl-CoA:acetate CoA transferase, but by three distinct CoA transferases, PGN_0725, PGN_1341, and PGN_1888. Gas chromatography/mass spectrometry (GC-MS) and spectrophotometric analyses were performed using crude enzyme extracts from deletion mutant strains and purified recombinant proteins. The experiments revealed that, in the presence of acetate, PGN_0725 preferentially utilized butyryl-CoA rather than propionyl-CoA. By contrast, this preference was reversed in PGN_1888. The only butyryl-CoA:acetate CoA transferase activity was observed in PGN_1341. Double reciprocal plots revealed that all the reactions catalyzed by these enzymes follow a ternary-complex mechanism, in contrast to previously characterized CoA transferases. GC-MS analysis to determine the concentrations of short chain fatty acids (SCFAs) in culture supernatants of P. gingivalis wild type and mutant strains revealed that PGN_0725 and PGN_1888 play a major role in the production of butyrate and propionate, respectively. Interestingly, a triple deletion mutant lacking PGN_0725, PGN_1341, and PGN_1888 produced low levels of SCFAs, suggesting that the microorganism contains CoA transferase(s) in addition to these three enzymes. Growth rates of the mutant strains were mostly slower than that of the wild type, indicating that many carbon compounds produced in the SCFA synthesis appear to be important for the biological activity of this microorganism.

Fracture strength testing of crowns made of CAD/CAM composite resins

PURPOSE The purpose of this study was to ascertain whether computer aided design/computer aided manufacturing (CAD/CAM) composite resin crowns have sufficient strength to withstand the bite force of the molar teeth. The null hypothesis was that the fracture strength of CAD/CAM composite resin crowns is lower than the average maximum bite force of the molar tooth. METHODS The crowns, which shape is the right maxillary first molar, were fabricated using four CAD/CAM blanks made of composite resins (Block HC: HC, KZR-CAD HR: HR, KZR-CAD HR2: HR2, Avencia Block: AVE) and one CAD/CAM blank made of lithium disilicate glass-ceramic (IPS e.max CAD: IPS), which was used as a control. Fracture strength of fabricated crowns bonded to metal abutment and biaxial flexural strength of the materials were evaluated. RESULTS The results of fracture strength test and biaxial flexural strength test showed different tendencies. The fracture strength of CAD/CAM composite resin crowns except HC ranged from 3.3kN to 3.9kN, and was similar to that of IPS (3.3kN). In contrast, biaxial flexural strength of CAD/CAM composite resins ranged from 175MPa to 247MPa, and was significantly lower than that of IPS (360MPa). CONCLUSIONS All CAD/CAM composite resin crowns studied presented about 3-4 times higher fracture strength than the average maximum bite force of the molar tooth (700-900N), which result leads to the conclusion that CAD/CAM composite resin crowns would have sufficient strength to withstand the bite force of the molar teeth.

Development of three-dimensional facial expression models using morphing methods for fabricating facial prostheses

PURPOSE It is essential to fabricate a best-fit three-dimensional (3D) facial prosthesis model capable of facial expressions. In order for the facial prosthesis to remain in position, especially around marginal areas subject to movement, a new method of making 3D facial expression models using time-series data allowing changes in facial expression by morphing technique was developed. METHODS Seven normal subjects and seven patients with nasal defects or nasal deformities participated in this study. Three distinct facial expressions (i.e., a neutral expression, smiled, and open mouthed) were digitally acquired with a facial scanner. Prepared template models were transformed to homologous models, which can represent the form as shape data with the same number of point cloud data of the same topology referring to the scanning data. Finally, 3D facial expression models were completed by generating a morphing image based on two sets of homologous models, and the accuracy of the homologous models of all subjects was evaluated. RESULTS 3D facial expression models of both normal subjects and patients with nasal defects were successfully generated. No significant differences in shape between the scanned models and homologous models were shown. CONCLUSIONS The high accuracy of this 3D facial expression model in both normal subjects and patients suggests its use for fabricating facial prostheses.

Biological and Biochemical Roles of Two Distinct Cyclic Dimeric Adenosine 3′,5′-Monophosphate- Associated Phosphodiesterases in Streptococcus mutans

Cyclic dimeric adenosine 3′,5′-monophosphate (c-di-AMP), a recently identified secondary messenger in bacteria, plays a role in several bacterial processes, including biofilm formation. It is enzymatically produced by diadenylate cyclase and cleaved by c-di-AMP phosphodiesterase. c-di-AMP is believed to be essential for the viability of bacterial cells that produce it. In the current study, the biochemical and biological roles of GdpP (SMU_2140c) and DhhP (SMU_1297), two distinct Streptococcus mutans phosphodiesterases involved in the pathway producing AMP from c-di-AMP, were investigated. Liquid chromatography-tandem mass spectrometry revealed that c-di-AMP was degraded to phosphoadenylyl adenosine (pApA) by truncated recombinant GdpP, and pApA was cleaved by recombinant DhhP to yield AMP. In-frame deletion mutants lacking the dhhP gene (ΔdhhP) and both the gdpP and dhhP genes (ΔgdpPΔdhhP) displayed significantly more biofilm formation than the wild-type and a mutant strain lacking the gdpP gene (ΔgdpP; p < 0.01). Furthermore, biofilm formation was restored to the level of the wild type strain upon complementation with dhhP. Optical and electron microscopy observations revealed that ΔdhhP and ΔgdpPΔdhhP mutants self-aggregated into large cell clumps, correlated with increased biofilm formation, but cell clumps were not observed in cultures of wild-type, ΔgdpP, or strains complemented with gdpP and dhhP. Thus, deletion of dhhP presumably leads to the formation of bacterial cell aggregates and a subsequent increase in biofilm production.

What you should know about malocclusion in prosthodontic treatment: Diagnostic concepts should not be confined to teeth alone: ─歯だけにとらわれない診かた考え方─

121 補綴歯科治療の目的の一つは異常な咬合を正常なも のに修復することである.診療ガイドラインの術式に 則り,規定した咬合位において補綴装置を使用して修 復することにより,正常な機能回復を図ることが可能 となる.ただし,補綴歯科治療を進めていくうえで知っ ておくべき咬合異常が存在しており,普段通りに補綴 歯科治療を行っても正常な機能が獲得されないことも ある.日本補綴歯科学会ガイドライン作成委員会の「歯 科医療領域 3 疾患の診療ガイドライン」に記載され ている咬合異常の診療ガイドラインでは,咬合異常 (malocclusion)とは,「上下顎の歯の静的・動的な 位置関係が正常ではなくなった状態.対向関係の異常, 咬合位の異常,咬合接触の異常,顎運動の異常,咬合 を構成する要素の異常などを包含する.」と定義され ている.そこで,治療方針を見誤らないようにするた めには,目前の患者における咬合異常の原因を明らか にすることが重要である. 一方,日常臨床においては原因の特定に苦慮する咬 合異常に遭遇することは少なくない.例えば,後天性 の開咬などの顎関節の変化に起因する二次的な咬合異 常,筋の過緊張やジストニアなど,筋の障害による咬 合異常,心身医学的な要因などによる咬合違和感な どである.日本補綴歯科学会診療ガイドライン委員 会の「咬合違和感症候群」に関するポジションペー パーでは,咬合違和感症候群とは,広義には,明ら かな咬合の不調和が認められる場合,また明らかな咬 合の不調和が認められない場合(いわゆる特発性)も 含めた咬合の違和感を訴える包括的病態.狭義には, 咬合とは無関係に特発的に発症する咬合の違和感を訴 える状態.2003 年に Clark と Simmons は “occlusal dysesthesia” を提唱しており「歯髄疾患,歯周疾患, 咀嚼筋ならびに顎関節疾患のいずれもが認められず, 臨床的に咬合異常が認められないにもかかわらず 6 カ月以上持続する咬頭嵌合位での不快感」に該当する 病態と定義している.これらの患者に対しては,歯や 歯列のことだけを視野に入れているとその対応におい て支障が生じる場合もある. そこで,(公社)日本補綴歯科学会第 126 回学術大 会の臨床スキルアップセミナーでは,表題のテーマを 企画し,臨床経験豊富な 2 名の先生方に顎関節,神経・ 筋,心理社会的因子など,幅広い観点からの咬合異常 の診かたと対応法について講演をいただいた.本稿は その講演内容をもとに先生方に要説いただいたもので ある. 山口泰彦先生(北海道大学)には,顎関節の形態変 化や筋障害に起因する二次的な咬合異常のいくつかの 主要パターンの特徴をご提示いただきながら,顎関 節,神経・筋を含めた幅広い観点からの咬合異常の診 かたと対応法について解説していただいた.松香芳三 先生(徳島大学)には,精神疾患に起因,あるいは末 梢から中枢神経系における情報伝達・情報処理機能に 起因するとされている咬合違和感に関して解説いただ いた. 日常臨床においては,咬合に関する異常感や違和感 の訴えに対応する客観的所見が確認できず,対応に苦 慮した症例を経験する場合がある.われわれ歯科医師