86 research outputs found

    Influence of intraradicular post and crown ferrule on the fracture strength of endodontically treated teeth

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    The aim of this study was to investigate the fracture strength of endodontically treated teeth restored with different posts and variable ferrule heights. Sixty freshly extracted human canines were treated endodontically and randomly assigned to 6 groups (n=10), being restored with custom-made cast post-and-core (CP0 and CP3 groups), prefabricated post and composite resin core (PF0 and PF3 groups), and composite resin (CR0 and CR3 groups). The CP0, PF0 and CR0 groups presented no ferrule and the CP3, PF3 and CR3 presented 3 mm of coronal structure. All teeth were restored with full metal crowns. The fracture strength was measured in a universal testing machine at 45o to the long axis of the tooth until failure. Data were analyzed statistically by 2-way ANOVA and Tukey's test (?=0.05). When the mean fracture strength values were compared (CP0 group - 820.20 N, CP3 group - 1179.12 N; PF0 group - 561.05 N; PF3 group - 906.79 N; CR0 group - 297.84 N; and CR3 group - 1135.15 N) there was statistically significant among the groups (p<0.05), except for the three groups with 3 mm of coronal remaining, which were similar to each other. The results of this study showed that the ferrule in crowns promoted significantly higher fracture strength in the endodontically treated teeth.O objetivo neste estudo foi avaliar a resistência à fratura de dentes tratados endodonticamente restaurados com diferentes pinos e diferentes alturas de remanescente dentinário da coroa. Sessenta caninos recém-extraídos foram tratados endodonticamente, separados em 6 grupos (n=10) e restaurados com núcleo metálico fundido (CP0 e CP3), pino pré-fabricado e núcleo em resina composta (PF0 e PF3) ou resina composta (CR0 e CR3). Os grupos CP0, PF0 e CR0 não possuíam férula e os grupos CP3, PF3 e CR3 apresentaram 3 mm de remanescente coronário. Todos os dentes foram restaurados com coroas totais metálicas. A resistência à fratura foi medida em máquina universal de ensaios com o longo eixo do dente posicionado a 45 graus em relação ao carregamento axial, até que ocorresse fratura. A análise de variância 2 critérios (?=0,05) mostrou diferença estatisticamente significativa entre os grupos. Quando as médias das forças para fratura foram comparadas (CP0 = 820,0 N; CP3= 1179,12 N; PF0 = 561,05 N; PF3 = 906,79 N; CR0 = 297,84 N; e CR3 = 1135,15 N) não foram observadas diferenças significativas entre os 3 grupos com 3 mm de remanescente coronal. Os resultados mostraram que a presença de férula em coroas aumenta significantemente a resistência à fratura de dentes tratados endodonticamente.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

    Comparison of the fracture resistance of endodontically treated teeth restored with prefabricated posts and composite resin cores with different post lenghts

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    OBJECTIVE: This study evaluated the fracture strengths of endodontically treated teeth restored with prefabricated posts with different post lengths. MATERIAL AND METHODS: Thirty freshly extracted canines were endodontically treated. They were randomly divided into groups of 10 teeth and prepared according to 3 experimental protocols, as follows; Group 1/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with post length of 5.0mm; Group 1/2 PP and Group 2/3 PP: teeth restored with prefabricated post and composite resin core (Z250) with different combinations of post length of 7.5mm and 10mm, respectively. All teeth were restored with full metal crowns. The fracture resistance (N) was measured in a universal testing machine (crosshead speed 0.5mm/min) at 45 degrees to the tooth long axis until failure. Data were analyzed by one-way analysis of variance (alpha=.05). RESULTS: The one-way analysis of variance demonstrated no significant difference among the different post lengths (P>;.05) (Groups 1/3 PP = 405.4 N, 1/2 PP = 395.6 N, 2/3 PP = 393.8 N). Failures occurred mainly due to core fracture. CONCLUSIONS: The results of this study showed that an increased post length in teeth restored with prefabricated posts did not significantly increase the fracture resistance of endodontically treated teeth

    Evaluation of the influence of application and handling technique in the retention strength of self-adhesive resin cements used in intra-radicular fiberglass posts

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    Atualmente, existem cimentos resinosos que dispensam o uso prévio de sistemas adesivos (autoadesivos) e aliam as vantagens dos cimentos resinosos às dos cimentos não resinosos, sendo recomendados para todas as restaurações indiretas, inclusive a cimentação de pinos intrarradiculares. Devido à falta de conhecimento do comportamento desses cimentos perante as diferentes técnicas de manipulação e aplicação, o objetivo deste trabalho foi avaliar a força de retenção de 3 cimentos autoadesivos, quando empregados na cimentação de pinos intrarradiculares de fibra de vidro. Para isso, foram selecionados 45 caninos humanos, divididos aleatoriamente em três grupos (N=15) diferenciados pelos cimentos: Grupo I - BisCem (Bisco), Grupo II - Breeze (Pentron Clinical Technologies, LLC) e Grupo III Maxcem (Kerr). Esses grupos foram divididos em três subgrupos, variando a técnica de aplicação e de manipulação: Subgrupo A - Ponta automisturadora/Ponta aplicadora, Subgrupo B - Espatulação/Lentulo, Subgrupo C - Espatulação/Centrix. O teste de push-out foi realizado com uma velocidade de 1 mm/min, e a força de retenção foi expressa em Mega Pascal (MPa). O cimento Breeze apresentou os maiores resultados médios para os subgrupos A, B e C (12,27 ± 3,19 Mpa; 13,65 ± 2,51 MPa; 13,64 ± 3,65 MPa), quando comparados aos cimentos Biscem (7,25 ± 2,37 MPa; 13,37 ± 1,80 MPa; 9,48 ± 2,38 MPa), e Maxcem Elite (7,87 ± 1,12 MPa; 7,21 ± 1,43 MPa; 9,89 ± 1,43 MPa. Somente para o cimento Biscem houve diferença estatística significante entre seus subgrupos. Assim, pôde-se concluir que, de acordo com os resultados deste estudo, a técnica de aplicação e manipulação pode influenciar na resistência retentiva, dependendo do cimento autoadesivo utilizado.Currently, there are resin cements that do not require prior use of adhesive systems (self-adhesive), and combine the advantages of resin cements with that of non-resin cements, and are recommended for all indirect restorations, including intraradicular cementation. Due to the lack of understanding about the behavior of these cements in the presence of the different handling and application techniques, the objective was to evaluate the retention strength of 3 self-adhesive cements, when used in cementing intra-radicular fiberglass posts. For this, 45 human canines were selected and divided randomly into three groups (N = 15) for different cements: roup I - Bisco (Bisco), Group II - Breeze (Pentron Clinical Technologies, LLC) and Group III - Maxcem (Kerr). These groups were divided into three sub-groups by varying the application and handling technique: Sub-group A - Automix/Point tip applicator, Sub-group B - Handmix/ Lentulo, Sub-group C Handmix/ Centrix. The test of push-out was performed with a speed of 1 mm / min, and the retention strength was expressed in Mega Pascal (MPa). The Breeze cement, showed the highest average for sub-groups A, B and C (12.27 ± 3.19 MPa, 13.65 ± 2.5 MPa, 13.64 ± 3.65 MPa)when compared to the Biscem cement (7.25 ± 2.37 MPa, 13.37 ± 1.80 MPa, 9.48 ± 2.38 MPa), and Maxcem Elite (7.87 ± 1.12 MPa, 7.21 ± 1 , 43 MPa, 9.89 ± 1.43 MPa. Only for the Biscem cement was there statistically significant difference between the sub-groups. Thus, one can conclude that according to the results of this study, the application and handling technique may influence the retentive strength depending on the self-adhesive cement used

    Feasibility and Safely of Oral Rehydration Therapy before Upper Gastrointestinal Endoscopic Submucosal Dissection

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    Background/Aims. Preoperative oral rehydration therapy (PORT), often used before surgery, is rarely performed before endoscopy. Only a few reports of PORT before upper gastrointestinal endoscopy are available. This study is aimed at evaluating the safety and feasibility of PORT before upper gastrointestinal endoscopic submucosal dissection (ESD). Methods. We used alginade water (125 mL, Nestle Co., Kobe, Japan) for PORT. Alginade water is a flavored sports drink, which is palatable and promotes wound healing due to a high concentration of alginate. We conducted a single-center single-arm prospective feasibility study of PORT in 244 patients who underwent upper gastrointestinal ESD. The group wherein PORT was administered up to two hours before ESD (n=120) was compared with the historical control group (non-PORT group, n=120). We investigated the total fluid intake, hematocrit change, complications due to PORT, complications during ESD, ESD procedure time, and length of hospital stay in each group. Results. The average fluid intake in the PORT group was 462.6 mL. No complications were observed due to PORT and ESD, and significant differences in the ESD procedure time or hospital stay was not noted. Conclusion. PORT up to two hours before upper gastrointestinal ESD is feasible

    Plasma Printing of an AISI316 Micro-Meshing Punch Array for Micro-Embossing onto Copper Plates

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    Packaging using thermoplastic molding for hollowed GaN chips were requested for a leak-proof micro-joining between plastic molds and copper-based substrates. The design and engineering of micro-textures is a key technology for putting leak-proof packaging into practice. In the present paper, a micro-meshing punch array was prepared using plasma-nitriding-assisted printing. Two-dimensional original patterns were screen-printed onto an AISI316 die substrate and plasma nitrided at 673 K for 14.4 ks (or 4 h). The unprinted surfaces were selectively nitrogen super-saturated to have more nitrogen content than 5 mass% and a higher hardness than 1200 HV. The printed surfaces were selectively sand blasted to fabricate the micro-meshing punch array for micro-embossing. A computer numerically controlled stamping system was utilized to describe the micro-embossing behavior onto copper substrates and to investigate how the micro-textures on the array was transcribed onto the copper. Reduction of takt time as well as flexibility in the micro-grooving were discussed with reference to the picosecond laser machining and mechanical milling processes

    Inhibition of nuclear factor-kappa B activation attenuates hydrogen peroxide-induced cytotoxicity in human lens epithelial cells

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    Aims: Hydrogen peroxide (H2O2) is the major oxidant involved in cataract formation. Lens epithelial cells have been suggested to be the first site of oxidative damage. The authors investigated the relationship between H2O2-induced cytotoxicity and activation of nuclear factor kappa B (NF-B) in human lens epithelial (HLE) cells. Methods: HLE B-3 cells were stimulated by various concentrations of H2O2 in the presence or absence of pyrrolidine dithiocarbamate (PDTC), a potent inhibitor of NF-B. H2O2-induced cytotoxicity was measured by lactate dehydrogenase cytotoxicity assay. Translocation of NF-B was examined by Western blot and immunocytochemistry using anti-p65 antibody. Results: H2O2-induced cytotoxicity increased in a concentration-dependent manner. PDTC treatment significantly suppressed the cytotoxicity induced by H2O2. After stimulated with H2O2, NF-B was found translocated from cytoplasm into the nuclei. PDTC treatment also inhibited the translocation of NF-B. Conclusions: NF-B signal pathway may be important in the development of H2O2-induced damage in HLE cells that is involved in cataractogenesis

    Increase in macrophage migration inhibitory factor levels in lacrimal fluid of patients with severe atopic dermatitis

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    Background and aims of the study Atopic dermatitis is a chronic inflammatory skin disorder that often involves some ophthalmic features. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that is associated with the generation of cell-mediated immune responses. Although serum MIF levels may be elevated in severe atopic dermatitis, the quantity of MIF in regional ocular fluid remains unknown. We measured MIF levels in tears (lacrimal fluid) of patients with atopic dermatitis. Patients and methods Tear samples were collected from 16 patients with atopic dermatitis, 10 patients with allergic conjunctivitis, and 15 healthy control subjects. The clinical severity of atopic dermatitis was evaluated according to the Scoring Atopic Dermatitis (SCORAD) index. The index was calculated by summing the following scores: extent criteria, intensity criteria, and subjective symptoms. Macrophage migration inhibitory factor levels were determined by a human MIF enzyme-linked immunosorbent assay. All comparisons were two-tailed, and P values <0.01 were considered as statistically significant. Results The mean MIF concentration in lacrimal fluid collected from healthy control subjects was 0.69±0.2 ng/ml. The mean tear MIF levels were 17.87±6.3 ng/ml in moderate-to-severe atopic dermatitis (SCORAD≥15, P=0.002), 0.93±0.08 ng/ml in mild atopic dermatitis (SCORAD<15), and 2.76±0.86 ng/ml in allergic conjunctivitis (P=0.008). Conclusions A proinflammatory cytokine MIF level was elevated in tears as well as serum in cases of severe atopic dermatitis. These results suggest that MIF may play an important role in the induction or enhancement of ophthalmic features related to severe atopic dermatitis
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