Odontogenic deep neck space infection in a patient with hyper-IgE syndrome : a case report

Hyperimmunoglobulin E syndrome is a primary immunodeficiency state that is characterized by eczema, recurrent skin and lung infections, and markedly increased levels of IgE. Odontogenic infection can spread to vital and deep structures in such immunocompromised patients. We report a case of a 19-year-old man with hyperimmunoglobulin E syndrome presenting deep neck space infection that had spread from periapical periodontitis of the lower molars. A computed tomography scan showed an area of bony destruction in the left mandible and abscess formation in the submandibular and submental spaces. The patient was successfully treated by cervical drainage, extraction of the causative teeth, and antibiotic therapy. The present case highlights the importance of adequate treatment of dental infections in immunocompromised patients

モルモット免疫グロブリンＧサブクラスの分離、同定とその生物学的意義について

モルモットを蛋白質抗原で免疫した場合には、主としてIgGクラスの抗体が産生され、IgG抗体は、さらにサブクラスIgG1、IgG2に分類される。両者は、生物学的な機能に関して著しく異った性質を示し、特にIgG1抗体はIgEクラスの抗体と同様に、自己組織感作能を持つアレルギー性抗体であることが知られている。生体防禦の立場から、この種の抗体が実際に果している役割、あるいは、免疫応答におけるこれらサブクラス抗体相互の関係は非常に重要な問題と思われるが、まだ充分な知見が得られていない。　本論文は、これらの問題へのアプローチとして、自己組織感作性抗体IgG1を中心に、IgG2抗体と比較しつつ、免疫応答における血中抗体の産生の様子、特異抗体としての抗原との反応性、IgG1抗体産生の時期とアレルギー性反応との関係について分子論的立場から研究を行った結果である。　この研究における第一の問題点は、同じ抗原に対して血液中に産生される特異抗体のみについてそのサブクラスを分離定量しなければならないことである。このためには、免疫原との抗原-抗体反応による特異抗体の定量を行うのと同時に、これらサブクラスを定量的に分離同定する必要があり、そのためには試薬としてモルモットサブクラスIgGにそれぞれに特異的な抗体を用いるほかに方法がない。しかも生物学的活性のみを示標とした解析と異り、物質的な分離を基盤とする本研究では、これらの試薬が完全なものでなければならない。こうした理由のもとに、まずモルモットIgG1，IgG2を同定するための基準として用いうる高純度標品の精製と、これらのサブクラス抗体をそれぞれ分離定量するための試薬として、それぞれに特異的な抗血清の調製を行った。　BSAで高度に免疫したモルモット血清から、物理化学的方法によってIgG1およびIgG2を単離し、これらを用いてそれぞれヤギを免疫して、抗-IgG1，抗-IgG2抗血清を得た。しかしながら、これらの抗血清は、相互の抗原と部分的な反応を示した。これは、両者の共通抗原性と、物理学的方法のみでは、完全な精製が不可能であることを意味している。したがって、活性吸着法を利用して、相互に交叉的に吸収操作を繰り返し、より純度の高い抗原を得て、これにより抗体の精製を、そしてこの精製抗体を用いてさらに抗原を精製するといった方法で、免疫学的に相互に混入が認められない標品を調製することに成功した。これらを用いることによって、モルモット血清中の微量のIgG1，IgG2抗体をそれぞれ分離定量することが可能となり、第II，第III章における研究の重要な基礎となっている。　第II章においては、破傷風トキソイド免疫における血中抗毒素抗体に関する研究結果である。市販トキソイドの力価検定には、モルモットの能動免疫での抗毒素産生能による方法が用いられているが、一定の免疫方法を用いても個体差があり、また抗体価の測定方法によっても変動が見られ、さらにアジュバンドの添加条件も抗毒素価や、動物の感作状態に大きく影響することが知られている。　この研究では、破傷風免疫モルモット血清中の主要抗体であるIgGに関して、それぞれの免疫の条件、および異った時期における抗毒素抗体IgG1の実際の分離定量を行い、それぞれの抗毒素価、および抗原との反応性の測定とから、上記力価検定における諸問題および過敏症反応との関係の有無などを主体に検討を行った。その結果、他の蛋白抗原による免疫と同様に、トキソイド免疫においても、その比較的初期では、IgG2抗体が優位に検出され、免疫の進行に伴ってIgG1抗体の急速な増加が見られ、二次あるいは高度免疫では、血中抗体価の約90％は、IgG1によって占められていることが示された。　また、分離した各抗毒素抗体価を、受身血球凝集反応、マウスでの毒素中和反応により測定した結果、IgG1とIgG2との間には、これらの抗体価の相対量に差が見出され、免疫の経過におけるIgG1抗体の優位な産生とから抗毒素価の変動は、これらのサブクラス抗体の相対量によるものであることを明らかにすることができた。またin vivoにおける中和反応では、サブクラス間に明らかな差が認められ、IgG1のもつ自己組織感作能との関連が推論された。　第III章においては、BSAを抗原としたモルモット抗体について、免疫の極めて初期に観察される皮フおよび全身性アナフィラキシー反応にIgG1抗体が実際に関与していることの証明であり、得られた結果から、この種の抗体の持つ生体防禦上での役割り、および、抗体産生におけるサブクラス抗体間の関連について考察を行った。　この研究を進めるに当っての第一の問題点は、従来の研究では生物学的活性が、各サブクラス抗体の実際量として求められていない点であり、第二の問題点は、もう一つの自己組織親和性抗体であるIgEの混入である。　最後の問題点は、生物学的反応が検出できる前後での微量抗体量の測定をしかもサブクラスごとに定量する方法の選択であった。　このため第I章で得られた精製標品を用いてPCA反応、受動全身性アナフィラキシー反応を惹起するのに必要なIgG1抗体の最小量の決定を行い従来示されていた値よりはるかに少量であること、IgG2抗体の共存の影響は、IgG1抗体の約20倍量でも無視し得ること、また感作時間についても明らかな延長が見られることなどを明らかにした、これらのデータをもとに、能動感作条件を抗原量を変えて求めた結果、BSA100μg、アルミニウムアジュバントと共に腹腔内注射後10～15日の間に皮膚アナフィラキシー反応の感作が成立し、全身性ショックはこれよりも2～3日間おくれてあらわれる結果が得られ、これらの様相は、受動性感作において観察されたと同じであった。この時期における血中抗体の測定は、放射免疫定量法を基本としたIgG1，IgG2抗体をそれぞれ分離定量できる間接法を用いて行い、その定量範囲はIgG1，IgG2の重量にして1～20ng（10^-9グラム）であることを確認した。測定結果は、アナフィラキシー反応の出現する時期においてすでに両サブクラス抗体の産生が認められ、個体により異るが、血清のml当りに換算して1～4μgの抗体を含んでおり、この濃度は、精製IgG1抗体による受動感作最少量と同じレベルであった。　また、IgE抗体の関与を除外するために、加熱処理、持続時間、あるいはブドウ球菌の膜成分であるProtein Aによるアナフィラキシー反応の阻害などの効果等を検討し、免疫初期の反応がIgG1抗体によるものであることを証明することができた。　以上の実験結果は、免疫の極めて初期において、IgG1，IgG2サブクラス抗体が平行して産生されていることを示すもので、これらの抗体産生を担当する細胞が、一つの抗原物質に対し独立に応答していることを意味している。したがってモルモットの高度免疫血清中に見られるIgG1抗体の選択的産生は、制禦機構をも含めた、免疫応答の二次的効果によるものと考えられ、またクラス間の抗体産生で知られているような継次的な関係は、サブクラス間には存在しないことを示すものと考えられる。　上記3章にわたる研究結果は、主として齧歯類に特徴的である自己組織親和性IgG1サブクラス抗体を中心にIgG2抗体と比較しつつ、分子性状と生物学的機能についての基礎を明らかにしてきたものであるが、これらをもとに、その生体防禦上の意義および免疫応答の遺伝的背景についても考察を加えた。Introduction It is well recognized that there are two subclasses in guinea-pig immunoglobulin G, one of them is an electro-phoretically slow type designated as IgG2, and the other is the faster type designated as IgG1, and the former is a major component in the normal serum and the latter is found only in a low level. From the data of the amino acid sequence analyses, it is known that these subclass immunoglobulin molecules are quite closer to each other than any other, but are contrasted with each other in the biological or functional properties. For instance, the subclass IgG1 antibodies are required for the homologous anaphylactic reactions, incapable of sensitizing heterologous tissues and fixing complement components in the classical pathway, but the subclass IgG2 antibodies are required for sensitizing heterologous tissues. It has been also known that when guinea-pigs were immunized with certain antigens emulsified in Freund\u27s complete adjuvant (FCA), the responses are found in both subclass antibodies, but are major in IgG2 and minor in IgG1 at an early course of the immunization, whereas with the antigen in Freund\u27s incomplete adjuvant (FIA), the products are major in IgG1 antibodies. From these facts it has been suggested that the responses of these subclass antibodies are susceptively influenced by the immunization procedures, particularly by the kinds and/or doses of adjuvant and antigen, and FCA is required for the intensive response of IgG2 subclass antibody. Furthermore, in the case of anti-hapten antibody, there are some evidences that when guinea-pigs were immunized with DNP-E.coli, regardless with or without of FIA the response of the anti-DNP antibodies are selectively dominant in IgG2 subclass. Therefore, it has been speculated that a certain sequential or preferential correlation exists between the responses of guinea-pig subclass antibodies. In our previous experiments on the immunization of tetanus toxoid, it was found that the symptoms of cutaneous anaphylaxis are observed variously in the guinea-pigs in an early course of the immunization under a specified condition. The observation seemed to show that homocytotropic antibodies had been produced in the immunized animals at so early stage. However, the biological roles of the antibodies in defence mechanisms in vivo and of the correlation between the responses of each subclass antibody have not yet understood. In this paper, in order to investigate further the distinctive biological properties and the distribution in antisera, the separation and quantitation of the subclass antibodies from the individual antisera obtained at various days in the early course of the immunization with the minimum dose of BSA required for the anaphylactic sensitization were carried out by a modified indirect method of radio-immuno assay using individually specific goat antibodies against the subclass IgG1 and IgG2. Materials and Methods Albumins : Bovine serum albumin (BSA, 3 times recrystallized) was obtained from Nutritional Biochemicals Co.(U.S.A.). Guinea-pig serum albumin (GSA) was prepared by saturated ammonium sulfate precipitation and DEAE-Sephadex A-50 column chromatography from the pooled normal sera. Guinea-pig subclass IgG\u27s and goat antibodies : The isolation and purification of these immunoglobulins and antibodies were performed according to the procedures described in our previous reports. In brief, the sera obtaind from guinea-pigs immunized with BSA in FCA were submitted to the isolation of the subclass IgG\u27s. The procedure consisted of the ion-exchange chromatography on a column of DEAE-Cellulose and the gel filtration on Sephadex G-150 column. Antiserums to these subclass immunoglobulins were obtained by immunizing goats with the isolated IgG1 and IgG2, respectively. The IgG fractions were isolated from these goat antisera according to the same procedures as used in the case of guinea-pig immunoglobulins, except for a little differences in the condition of column chromatography. The isolated antibody preparations were strongly reacted with each corresponding antigen, but still reacted weakly with each other. So, in order to obtained the subclass specific antibody, the antibody preparations were cross-absorbed with each other subclass IgG coupled to CNBractivated Sepharose 4B. After the repeated absorption, these preparations did not show any precipitation reaction with the heterologous antigens and the other serum proteins. The specificity of these antibodies will be cofirmed in the radio-immuno assay under Experiments and Results. Utilizing the specific antibodies, the guinea-pig subclass IgG\u27s were further purified by cross absorptions with these antibody immunoadsorbents. These purified antigens and antibodies were used in the following experiments. Immunoelectrophoresis and double diffusion tests : Immunoelectrophoresis in 1.0% agar gel was done using a veronal buffer pH 8.6, μ;0.05. An electrophoretic rum of 1.5 hours was obtained using 160 V. Double diffusion precipitin tests were done using 1.2% agar dissolved in borate buffer pH 8.0. Determination of protein : The absorbancy at 280 nm was used for calculating protein concentration. The values of E^1.0%_1.0cm were taken as 14.1, 14.0 and 7.0 for guinea-pig IgG, goat IgG and BSA, respectively. Immunization of guinea-pig : Randomly bred Hartley strain guinea-pigs of female, weighing 300～350g were used. Aminals were received single intraperitoneal injection of various amounts of BSA mixed with aluminum adjuvant. Anaphylactic reactions : Passive cutaneous anaphylaxis (PCA) : Several dilutions of purified IgG1 antibody or test samples (immunized serum from individual bleedings) were injected intradermally in 0.1 ml quantities into shaved dosal of normal guinea-pigs in duplicate. After a short latent period (3 hours) or a long latent period (24 hours) the animals were injected intravenously (i.v.) with 1.0 ml of 0.5 per cent solution of evans blue in saline (0.15 M NaCl) containing 1.0 mg of BSA. Thirty minutes after the antigen injection, the animals were killed and the skin was inverted and the lesion diameter was measured on the outer (or inner ) surface of the skin with a slide calipers. The reactions were graded according to the diameter of the colored spots ; 0 = no reaction, 1/2 = less than 5 mm, 1 = from 5 to 10 mm, 2 = from 10 to 15 mm, 3 = from 15 to 20 mm, 4 = more than 20 mm. Active cutaneous anaphylaxis (ACA) : At first, guinea-pigs were intraperitoneally injected with various amounts of BSA in aluminum precipitates, and at various days after the injection, various amounts of BSA (1.0, 0.1, 0.01 mg) in 0.1 ml volume were intradermally injected to the shaved dorsal region of the actively sensitized guinea-pigs, and at the almost the same time, 0.5 ml of 1.0% evens blue solution was intravenously injected the animal. The skin reactions with blue spots were appeared with in a few minutes and completed with in 30 minutes after the antigen injections. Animals were killed, and the sizes of spots were measured and graded according to the similar way used in the PCA reaction. Passive systemic anaphylaxis (PSA) : Various amounts of the purified IgG1 antibody were injected intravenously into normal guinea-pig weighing 300～350 g. Forty eight hours later, the animals were intravenously injected with 2.0 mg of BSA in 1.0 ml of saline. The reactions were graded by the observed symptoms of anaphylactic shock as follows ; 0 = no reaction, 1 = slight reaction, 2 = moderate reaction, 3 = severe reaction, 4 = death. Active systemic anaphylaxis (ASA) : The sensitized guinea-pigs as well as the ACA, were intravenously with 2.0 mg of BSA in saline, the observed symptoms of the systemic anaphylaxis were graded as in the case of PSA. Radioactive iodination of proteins : Purified immunoglobulins (guinea-pig IgG1, IgG2 and goat anti-IgG1, -IgG2) and BSA were iodinated by the chloramine T method described by Greenwood et al. (3) by using carrier-free Na ^I (New England Nuclear U.S.A.). The solution containing 0.1～1.0 mg of the protein preparation was mixed with about 2～20 μCi of ^I, and a small portion of chloramine T freshly dissolved in 0.005 M phosphate buffered saline pH 7.2 (PBS) were added to the reaction mixture, to be a ratio of chloramine T to protein 1 : 20 (w/w). The reaction mixture was allowed to proceed in an ice cold for 10 minutes and then terminated by addition of sodium hydrosulfite (50 μg/mg of protein ). Unbound ^I was removed from the sample by chromatography on a 1.2 x 30 cm column of Bio-gel P-10 (Bio-Rad Laboratories, U.S.A.) equilibrated in PBS. The labeled samples were throughly dialysed against a lot of PBS. The specific radioactivity bound to protein was determined by 10% trichloroacetic acid (TCA) precipitation of a small portion of the sample and more than 98% of the total counts of labeled material was found in the precipitate. Experiments and Results Characterization of goat antibody immunoglobulins : In order to comfirm, the mono-specificity of the purified goat antibodies to the guinea-pig subclass antibodies were tested against these antigens by immunoelectrophoresis and double diffusion in agar gel. The results of the immunoelectrophoretic analyses showed that the each antibody reacted to the corresponding subclass immunoglobulin alone with a single precipitation arc, and never reacted with the other guinea-pig serum proteins including IgG2, respectively. They were further confirmed even by the more sensitive radio-immuno assay, that is, the radioactively labeled antibodies quantitatively bound to the solid phase immunoadsorbent made of the homologous antigen, the percentages of the bound cpm to the total one were 9.0% for the anti-IgG1, and 6.5% for the anti-IgG2, but only less than 0.15% was cross-reactable to the heterologous antigen or guinea-pig serum albumin for the respective antibodies. These percentage values were also used to estimate the specific antibody contents of the anti-subclass antibody IgG. Characterization of guinea-pig IgG1 and IgG2 immunoglobulins : Because the purified guinea-pig subclass antibodies were prepared from pool of the hyper immunized antisera with bovine serum albumin, these preparations contained an appreciable amounts of anti-BSA antibodies belonging each of the subclass immunoglobulins. The antibody contents of each preparation could be determined by the direct radio-immuno assay using polystyrene tubes coated with BSA. The radio-activily labeled IgG1 and IgG2 preparations quantitatively bound to the solid phase immunoadsorbent of BSA, and the percentage values of the bound cpm to the total one were taken as the specific anti-BSA activities involved in the subclass immunoglobulins, that is, 41% for IgG1 and 16% for IgG2. The antibody concentrations of the subclass preparations were caluculated from these percentage values. PCA activity of the purified IgG1 : The IgG1 preparation used for the experiments was containd a known amount of anti-BSA antibody as described just above. Therefore, PCA reactions could be sensitized with this IgG1 and be induced by the challenge of BSA antigen. To determine the minimum dose for passive sensitization and the latent period, normal guinea-pigs were intradermally injected with various amounts of the IgG1, and various hours later the animals were challenged by the procedure described in Methods. The positive PCA reactions were observed at 3 hours after the injection with more than 0.1 μg of the IgG1 antibody (in 0.1 ml volume). However, at the latent period prolonged to 24 hours, the minimum dose decreased as about one tenth of the above value. The PCA reaction in the following experiments were performed under the condition. Recently, it is established that guinea-pigs produced two distinct types of homocytotropic antibody, one belong to the IgG1 subclass and the other to IgE class of immunoglobulin and they are functionally distinguishable by their biological properties. In this paper the criteria were applied for the distinction between IgG1 and IgE, that is, IgE antibody loses its ability to induce PCA reaction by heating at 56°C for 2 hours, and persists in the passively sensitized skin for over 10 days, finally IgG1 bound to Protein A from staphylococcus aureus loses its anaphylactic reactivity. The results were obtained that no interference of the anaphylactic reactions elicited the IgG1 preparation by heating was observed and the skin persistence was completely extinguished with in 3 days and the inhibition of the PCA reaction by addition of Protein A was observed. Passive systemic anaphylaxis (PSA) of IgG1 : To determine the minimum dose of passive sensitization, normal guinea-pigs were injected intravenously with the purified IgG1 in various amounts, and 48 hours later, the anaphylaxis both of fatal systemic and of local reaction to the guinea-pigs were found with the administration of the IgG1 containing 50 μg of the anti-BSA antibody protein, but less than this quantity, only the local reaction was positive and with less than 10 μg of the antibody, any anaphylactic reaction could not be found. The effect on the anaphylaxis of the IgG1 antibody by coexisting IgG2 antibody were tested and no effect was found by the addition of over twenty times higher quantities of the IgG2 antibody than that of the IgG1 antibody. Anaphylactic reactions in the animals sensitized with various dose of BSA : Guinea-pigs were intraperitoneally sensitized in aluminum precipitate with various amounts of BSA and both anaphylactic reactions were investigated in these groups of 4 animals. The weak ACA reactions were observed in the groups immunized with 1.0 μg of BSA at 10 days after the injection, but systemic one did not. The apparent anaphylactic reactions were found in these both groups with 10 and 100 μg of the antigen at least in 15 days after the injection, but the fatal systemic one did not, and at 20 days later, the fatal or severe systemic reaction were observed in these two groups. Determination of the subclass antibodies in the sensitized animal sera : It was considerably hard to quantify a very minute amount of antibody by the conventional techniques, furthermore the procedure had to be able to determine each quantity of the specific subclass antibodies using a small volume of the antisera. From these reasons, the radio-immuno assay with some modifications has been successfully applied to this purpose. The procedures of the indirect radio-immuno assay consist of three reaction steps as follows, 1) coating polystyrene tubes with BSA, 2) binding anti-BSA antibodies in guinea-pig antiserum, finally, 3) binding radio actively labeled anti-guinea-pig subclass antibodies specific for each of the subclass IgG\u27s. The practical procedures would be described in more detail. One ml portions of 1.0% BSA solution were pipeted into polystyrene tubes and stood for 1 hour at room temperature. The solutions were aspirated and then washed 3 times with PBS. To block the remaining vacant site, the tubes were filled with 1.0% solution of GSA in PBS, and allowed to stand for 1 hour at room temperature, then the GSA solution was aspirated and washed 3 times with PBS. The second, various amounts of the primary antibodies (guinea-pig anti-BSA IgG1 and IgG2) and 0.1 ml portion of GSA solution were added to the tubes, the tubes were incubated for 24 hours at room temperature with rotatory stirrer, the solution was removed and washed 3 times with PBS. Finally, ^I-labeled secondary antibody (goat anti-guinea-pig IgG1 and IgG2) and 0.1 ml portions of 1.0% GSA solution were added to the primary antibody bound tubes, respectively. The tubes were incubated for 24 hours at room temperature by rotation, washed 3 times with PBS and then the remaining radio activities in tubes was counted with auto-gamma scintillation spectrometer (Model 5320, Packard U.S.A.). The correlations between the quantities of the subclass antibodies and the radioactivity of the specific antibodies against these subclass IgG\u27s were obtained. The quantitating reference curves for each subclass antibody were used for the actual determinations of the antibodies in the antiserum obtained in an early stage of the immunizations. In order to investigate the sensitivity and accuracy of this method the amounts of the primary antibodies bound to the antigen coated tubes were directly determined using each of the ^I-labeled subclass IgG\u27s in various concentrations. In separate experiments up to 1.5 μg of the primary antibodies were quantitatively bound to the tubes in both cases, but with more than this quantity, the bindings were gradually saturated and the quantitativeness was unestablished in the both cases. The binding rates of the antibodies were also determined at various incubation hours in these measurments, and it was found that more than 90% of the ^I-labeled antibodies were able to bind on the coated tubes within a few hours. To determine the optimal concentration of the ^I-labeled secondary antibodies, these antibodies were added to the tubes combined with given amounts of the radioactively non labeled IgG1 and IgG2. At two different concentrations (200 and 400 ng) of the antibodies, the amounts of the bound primary antibodies in both cases, and the reference curves for the determinations of each subclass antibody were obtained, and the measurable ranges of the assay were found to be 1 to 20 ng of the antibodies. Under the coditions determined in the above reactions, the guinea-pigs immunized with 100 μg of BSA in aluminum precipitates were bled from the ear vein in various days after the immunization. The result indicated that both IgG1 and IgG2 antibodies were concomitantly detectable in the serum obtained on the 10th day after the immunization. In 15th day, it was found that the most of the increase of antibody contents was due to the production of IgG1 antibody, and the concentration of IgG2 antibody was gradually increased. PCA activity of antiserums of individual bleedings at early stage of immunization : To examine PCA activity of the antiserum obtained in the early stage of immunization, normal guinea-pigs were injected intradermally with the test antiserum in a various dilutions, and 24 hours later the animals were challenged by intravenous injection of 1.0 mg BSA in 0.5% evans blue solution. The results shown that the degree of PCA reactions were in proportional to their antibody concentration determined above. Discussion It is well known that antibody responses are susceptively influenced by immunization procedures. In the case of

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本稿では、2010年5月に発足した英国連立政権が取り組む「大きな社会」構想を取り上げ、その特徴を明らかにしている。大きな社会は、自由民主党と連立政権を組む保守党が、労働党から政権を奪還するために2009年に提唱した構想である。これは、人々が政府の提供する公共サービスよりも、コミュニティにおける支え合いを重視して生活できるように、政府の役割を公共サービスの提供から、そうした支え合いを支援する役割へと変革させようとするものである。英国では政府による生活への過度の介入を好まない考え方が根強く、大きな社会構想に対する評価は一定高い。その一方で、大きな社会における新たな政府の役割とは具体的に何かがはっきりしないまま、先行的に公共サービスから財政資金が引き揚げられる事態となっている。こうした限界を乗り越えて大きな社会構想を着実に実現するためには、コミュニティの担い手を育成することが必要不可欠である

“All-on-Four”コンセプトに基づいて即時荷重を適用したインプラントの力学解析

PURPOSE: The purpose of this study was to investigate the biomechanical behavior of immediately loaded implants in an edentulous mandible according to the "All-on-Four" concept. METHODS: A 3D-finite element model of an edentulous mandible was constructed. Four implants were placed between the bilateral mental foramen according to "All-on-Four" concept. A framework made of titanium or acrylic resin between the bilateral first molars was modeled. Immediate loading and a delayed loading protocol were simulated. A vertical load of 200N was applied at the cantilever or on the abutments region of the distal implants, simulating the absence of a cantilever. RESULTS: The peak principal compressive strains in the immediate loading models resulted in 24.0-35.8% and 26.4-39.0% increases compared with the delayed loading models under non-cantilever loading and cantilever loading, respectively. The loading position greatly affected the principal compressive and tensile strain values. The peak principal compressive strains in non-cantilever loading resulted in a 45.3-52.6% reduction compared with those in cantilever loading. The framework material did not influence the peak compressive and tensile strain. The maximum micromotion at the bone-implant interface in the immediate loading models was 7.5-14.4μm. CONCLUSIONS: Mandibular fixed full-arch prostheses without cantilevers may result in a favorable reduction of the peri-implant bone strain during the healing period, compared with cantilevers. The maximum micromotion was within the acceptable limits for uneventful implant osseointegration in the immediate loading models. Framework material did not play an important role in reducing the peri-implant bone strain and micromotion at the bone-implant interface.博士（医学）・乙第1398号・平成29年3月15日Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved

Effect of clenching on biomechanical response of human mandible and temporomandibular joint to traumatic force analyzed by finite element method

Purpose: The purpose of the present study was to analyze the effect of clenching on the biomechanical response of human mandible and temporomandibular joint (TMJ) to traumatic force by the finite element (FE) method. Material and Methods: FE models of the mandible and the TMJ in resting and clenching positions were prepared. Distribution and magnitude of von Mises stress were analyzed by applying force as a point load in the symphyseal, canine, body and angle regions of the mandible. In addition, strain energy density (SED) at the articular disc and in posterior connective tissue of TMJ was analyzed. Results: In the resting position, von Mises stress was mainly concentrated at the condylar neck and in the retromolar region of the mandible. In the clenching position, the stress at the condylar neck decreased in all loadings. The stress in the retromolar region similary decreased in the symphyseal, canine and body loading, respectively; however, higher stress was observed in the retromolar region on the loading side in the angle loading. High SED was generated at the articular disc and in posterior connective tissues of TMJ in the resting position. The SED in these tissues decreased in all loadings in the clenching position. Conclusions: Clenching generally reduces stress at the condylar neck and in the retromolar region of the mandible, and strain energy at the articular disc and in posterior connective tissue of TMJ by traumatic forces on the mandible; however, clenching induces greater stress in the retromolar region on the loading side by traumatic force to the angle region

Free Flap Blood Flow Evaluated Using Two-Dimensional Laser Speckle Flowgraphy

Objective. We investigated the efficiency of laser speckle flowgraphy for evaluating blood flow in free flaps used for plastic surgery. Methods. We measured blood flow using a visual laser meter capable of providing two-dimensional color graphic representations of flow distribution for a given area using a dynamic laser speckle effect. Using laser speckle flowgraphy, we examined the blood flow of 20 free flaps applied following the excision of head and neck tumors. Results. After anastomosis of the feeding and draining blood vessels and sewing the flap, musculocutaneous (MC) flaps showed significantly lower blood flow than jejunal or omental flaps (P < .05). The ratio of blood flow decrease from the edge to the center was significantly greater in MC flaps than in jejunal or omental flaps (P < .001). Conclusion. Laser speckle flowgraphy is useful for the perioperative measurement of blood flow in free flaps used in plastic surgery. This method is a highly useful, practical, and reliable tool for assessing cutaneous blood flow and is expected to be applicable to several clinical fields

腓骨皮弁による下顎骨再建術術後のインプラント周囲軟組織における治療方法の検討

In maxillofacial reconstruction implant treatment, unsatisfactory soft tissue treatment of the area around the implant may lead to inflammation. As a result, appropriate soft tissue treatment is critical. To the best of our knowledge, there are no studies that compare the different tissue treatment methods available. Hence, in this study, we compare three soft tissue treatment methods around implants after mandibular reconstruction is achieved with a fibula-free flap. Out of 33 patients who underwent mandible reconstruction using fibula-free flaps between 2006 and 2015, 5 were selected for this study. A total of 17 implants were used for treatment by the final prosthetics of the five patients. Three soft tissue treatment methods with free gingival graft (FGG) were evaluated, namely, installing a splint in a modified abutment to protect the wounded area during a palatal mucosa transplant (method 1), installing a splint or dentures to a locator abutment (method 2), and the use of screw-in fixed dentures (method 3). The method that could guarantee the widest keratinized mucosa was the screw-in fixed denture method. The results of our study indicated that employing screw-in fixed dentures for FGG may be a useful soft tissue treatment for mandible reconstruction implants.博士（医学）・乙第1491号・令和2年12月24日Copyright © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)