Propriedades físico-químicas dos cimentos AH Plus e Sealer Plus: tempo de endurecimento e escoamento

Introdução: O tratamento endodôntico busca sanificar o sistema de canais radiculares para permitir adequada obturação tridimensional. Para tanto, necessita-se de materiais plásticos, como a guta-percha, associados a cimentos en- dodônticos com adequadas características físico-químicas. Métodos: Comparação das propriedades físico-químicas tempo de endurecimento e escoamento dos cimentos endodônticos AH Plus e Sealer Plus, de acordo com a especificação 57 da American National Standard Institute/American Dental Association para materiais obturadores. Resulta- dos: O tempo de endurecimento do AH Plus foi de 1178 mi- nutos e do Sealer Plus foi de 422 minutos. O escoamento do APlus foi de 3259 milímetros e do Sealer Plus, 3150 milímetros. Conclusões: O tempo de endurecimento do AH Plus foi maior quando comparado ao do cimento Sealer Plus, e não houve diferença estatística no escoamento entre os cimentos estudados.

Material compósito de fibra da folha do abacaxizeiro (Ananas comosus) para uso no ambiente construído

Resumo Observa-se o crescente interesse pela sustentabilidade dos recursos naturais de nosso planeta. A arquitetura, imersa em um dos setores industriais responsáveis por grandes transformações do ambiente construído, mostra-se um canal para a incorporação racional de materiais com viés ecológico. Este artigo aborda pesquisa cujo objetivo foi o desenvolvimento de painéis compósitos de fibra da folha do abacaxizeiro e resina vegetal. O texto contempla a descrição dos procedimentos experimentais adotados e discute os resultados das caracterizações físicas - massa específica, teor de umidade e absorção de água - e mecânicas - resistências à flexão e à tração, e módulo de elasticidade em tração. O compósito foi desenvolvido com a adoção de diferentes teores de fibras, empregadas no sentido longitudinal. A fim de recomendar usos para os compósitos confeccionados, realizou-se comparação com o ANSI A208.1 - American National Standard Institute (ANSI, 2016), procedendo-se à simulação computacional, por meio da modelagem paramétrica via Rhinoceros 3D 5.12, Grasshopper 0.9.0076 e Karamba 3D 1.3.0. Os resultados experimentais indicaram um material com valores médios de massa específica entre 610 kg/m3 e 760 kg/m3, e resistência à tração entre 56,27 MPa e 81,58 MPa, direcionando sua classificação como painel compósito de partícula. A modelagem paramétrica reforçou as aplicações do produto no ambiente construído.

Physical and Mechanical Properties Evaluation of Corncob and Sawdust Cement Bonded Ceiling Boards

This study considered the production of composite ceiling boards from both agricultural and industrial wastes. Boards with different blending proportions by weight of cement, corncob and sawdust (Cem:Ccb:Swd) were produced and tested. Physical and mechanical tests such as Water Absorption (WA), Thickness Swelling (TS), Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) were carried out on the products. The findings revealed that the board with Cem:Ccb:Swd blending proportion 50:10:40 gave the highest values of MOE and MOR and also had the lowest values of WA and TS. The MOE and MOR values of 3.432 are both higher than the minimum values of 550 N/mm2 and 3 N/mm2 specified for MOE and MOR respectively by the American National Standard Institute, for general-use particle boards. The cement content is inversely proportional to the physical properties and directly proportional to the mechanical properties.

Radiopacity of Mineral Trioxide Aggregate with and without Inclusion of Silver Nanoparticles

ABSTRACT Aim The aim of this study was to investigate the inclusion of silver nanoparticles (Ag NPs) in the mineral trioxide aggregate (MTA) composition to know which changes will result in the radiopacity of the material. Materials and methods The experiment was performed according to the American National Standard Institute/American Dental Association specification no. 57/2000 and ISO 6876/2001. Five plates with five holes measuring 1 mm in depth and 5 mm in internal diameter were filled according to the different experimental groups as follows: white mineral trioxide aggregate (WMTA) + NP50 – W MTA with liquid Ag NP 50 ppm, WMTA + NP30 – W MTA with liquid Ag NP 30 ppm, WMTA + NP22 – W MTA with liquid Ag NP 22 ppm, WMTA + NPP – white MTA with liquid Ag NP and powder 1%, WMTA (control). After filling the plates, they were kept in an incubator at 37°C in relative humidity for setting. Each sample was positioned along an aluminum step-wedge placed above the Opteo digital sensor system. The image was divided into four quadrants, and three readings were made for each quadrant to render the average of each quadrant. The resulting data were submitted to Kruskal–Wallis and Dunn's tests. Results The results showed statistically significant differences between WMTA + NP30, WMTA + NP22, and WMTA + NPP interactions compared with WMTA (control) (p < 0.05). The radiopacity was in descending order: WMTA + NPP, WMTA + NP22, WMTA + NP30, MTA + NP50, and WMTA. Conclusion Silver NPs changed the radiopacity of WMTA, being more evident in WMTA + NP powder at 1% weight. Clinical significance The low radiopacity of MTA makes it difficult for any radiographic observation. The Ag NPs appear as an alternative, being an excellent radiopacifier as they have excellent antimicrobial property and relatively low toxicity. How to cite this article Mendes MSS, Resende LD, Pinto CA, Raldi DP, Cardoso FGR, Habitante SM. Radiopacity of Mineral Trioxide Aggregate with and without Inclusion of Silver Nanoparticles. J Contemp Dent Pract 2017;18(6):448-451.

Evaluation of the Radiopacities of Bulk-fill RestorativesUsing Two Digital Radiography Systems

SUMMARY This study investigated the radiopacity values of bulk-fill restoratives by using two digital radiography systems. Nine bulk-fill restoratives and a conventional composite were used in the study. Six disc-shaped specimens were prepared from each of these materials, three each at thicknesses of 1 mm and 2 mm, and tooth slices with these same thicknesses were obtained. As a control, an aluminum step wedge varying in thickness from 0.5 to 10 mm in was used. Three specimens of each of the materials, together with the tooth slice and the aluminum step wedge, were placed over a complementary metal oxide semiconductor (CMOS) sensor and a storage photostimulable phosphor (PPS) plate system and exposed using a dental x-ray unit. The images were analyzed using a software program to measure the mean gray values (MGVs). Five measurements were obtained from each of the restorative materials, the enamel, the dentin, and the stepwedge. The MGVs were converted to the equivalent aluminum thicknesses. Three-way analysis of variance (ANOVA) was used to determine the significance of the differences among the groups. A Tukey test was applied for pairwise comparisons (p&lt;0.05). All composite-based restoratives were found to have greater radiopacities than enamel or dentin. Equia Fil had the lowest radiopacity value. Radiopacity increased as the thicknesses of the restorative material increased. The CMOS system showed significantly higher radiopacity values than the PSP system. In conclusion, all investigated bulk-fill restoratives passed the International Organization for Standardization and American National Standard Institute/American Dental Association requirements for radiopacity values when evaluated with the two digital radiography systems.

Comparative Analysis of Selected Physicochemical Properties of Pozzolan Portland and MTA-Based Cements

Physicochemical properties of pozzolan Portland cement were compared to ProRoot MTA and MTA BIO. To test the pH, the samples were immersed in distilled water for different periods of time. After the pH analysis, the sample was retained in the plastic recipient, and the electrical conductivity of the solution was measured. The solubility and radiopacity properties were evaluated according to specification 57 of the American National Standard Institute/American Dental Association (ANSI/ADA). The statistical analyses were performed using ANOVA and Tukey’s test at a 5% level of significance. Pozzolan Portland cement exhibited pH and electrical conductivity mean values similar to those of the MTA-based cements. The solubilities of all tested materials were in accordance with the ANSI/ADA standards. Only the MTA-based cements met the ANSI/ADA recommendations for radiopacity. It might be concluded that the pH and electrical conductivity of pozzolan Portland cement are similar to and comparable to those of MTA-based cements.

KAJIAN MANFAAT KEANGGOTAAN ORGANISASI STANDAR MANCANEGARA BERDASARKAN PERTIMBANGAN EKONOMI

<p>Economic study of the membership in standard organizations of foreign countries have to be viewed from the benefit received by the pertinent state or institute compared to the obligation which must be fulfilled. Similarly, in chosing the standard organization of foreign countries to join, the benefit and service received from becoming organizational member of the foreign countries is a very significant factor. But, beside the benefit, the sector area of the foreign countries standard organization related to the circumstance from institute or state to join needs to be considered. It is needed to consider whether the sector have important position in the state economies especially from its exporting ability. Standard of foreign countries which focussed at certain sector or only give benefit and service of certain sector might not be effective enough to a company or state to participate if the state and the company does not cover the same sector.<br />This study used descriptive method with a view to make description, systematic formulation, factual and accurate with evidence obtained, by studying the nature of and also relation among phenomenon under the study. Pursuant to result of the study from level of benefit and obligation in getting information and expense of a success membership, among 10 organization of standard of foreign countries in the priority and strategic for Indonesia to join, started from highest to lowest priority is: British Standard Institute (BSI), Japan Industrial Standard (JIS), American Oil Chemical Society (AOCS), Association of Analytical Communities (AOAC-International), American National Standard Institute (ANSI), American Petroleum Institute (FIRE), Deutchland Institute for Normung (DIN), American Society of Mechanical Engineers (ASME), Australian Standard (AS), and American Association of State Highway and Transportation Officials (AASHTO).</p>

FSQL

The SQL language was essentially developed by Chamberlin and Boyce (1974) and Chamberlin et al. (1976). In 1986, the American National Standard Institute (ANSI) and the International Standards Organization (ISO) published the standard SQL-86 or SQL1 (ANSI, 1986). In 1989, an extension of the SQL standard, called SQL-89, was published, and SQL2 or SQL-92 was published in 1992 (ANSI, 1992). SQL2 basically provided new types, constraints (such as checks or unique predicates), it supported subqueries in UPDATE and DELETE operations, and in the FROM clause, operator IN, ANY and ALL, CASE constructor, JOIN, UNION, INTERSECT and EXCEPT operators and the modification of base table through views. In the latest version of SQL standard, SQL 2003, major improvements have been made in a number of key areas. Firstly, it has additional object-relational features, which were first introduced in SQL-1999. Secondly, SQL 2003 standard revolutionizes SQL with comprehensive OLAP features and data-mining applications. Thirdly, SQL 2003 integrates popular XML standards into SQL (SQL/XML). Finally, numerous improvements have been made throughout the SQL 2003 standard to refine existing features.