RESUMEN

The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05). The obtained contraction forces were: Grandio = 12.18 +/- 0.428N; Filtek Z 250 = 11.80 +/- 0.760N; Filtek Supreme = 11.80 +/- 0.707 N; and Admira = 11.89 +/- 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 +/- 0.0357%; Filtek Supreme = 0.36 +/- 0.0438%; Admira = 0.25 +/- 0.0346% and Grandio = 0.16 +/- 0.008%. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 +/- 2.160 microm; Filtek Supreme = 10.66 +/- 1.211 microm; Admira = 11.16 +/- 2.041 microm and Grandio = 10.50 +/- 1.224 microm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization) and third method (wall-to-wall shrinkage). The composite resins obtained with the second method (Teflon method) differed significantly regarding gap formation.

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RESUMEN

The aim of this study was to compare the shrinkage stress of composite resins by three methods. In the first method, composites were inserted between two stainless steel plates. One of the plates was connected to a 20 kgf load cell of a universal testing machine (EMIC-DL-500). In the second method, disk-shaped cavities were prepared in 2-mm-thick Teflon molds and filled with the different composites. Gaps between the composites and molds formed after polymerization were evaluated microscopically. In the third method, the wall-to-wall shrinkage stress of the resins that were placed in bovine dentin cavities was evaluated. The gaps were measured microscopically. Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05). The obtained contraction forces were: Grandio = 12.18 ± 0.428N; Filtek Z 250 = 11.80 ± 0.760N; Filtek Supreme = 11.80 ± 0.707 N; and Admira = 11.89 ± 0.647 N. The gaps obtained between composites and Teflon molds were: Filtek Z 250 = 0.51 ± 0.0357 percent; Filtek Supreme = 0.36 ± 0.0438 percent; Admira = 0.25 ± 0.0346 percent and Grandio = 0.16 ± 0.008 percent. The gaps obtained in wall-to-wall contraction were: Filtek Z 250 = 11.33 ± 2.160 µm; Filtek Supreme = 10.66 ± 1.211µm; Admira = 11.16 ± 2.041 µm and Grandio = 10.50 ± 1.224 µm. There were no significant differences among the composite resins obtained with the first (shrinkage stress generated during polymerization) and third method (wall-to-wall shrinkage). The composite resins obtained with the second method (Teflon method) differed significantly regarding gap formation.

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RESUMEN

The purpose of this study was to evaluate the individual contraction force during polymerization of a composite resin (Z-250), a flowable composite (Filtek Flow, FF) and a resin-modified glass ionomer cement (Vitrebond, VB), and the transmission of Z-250 composite resin polymerization contraction force through different thicknesses of FF and VB. The experiment setup consisted of two identical parallel steel plates connected to a universal testing machine. One was fixed to a transversal base and the other to the equipment's cross head. The evaluated materials were inserted into a 1-mm space between the steel plates or between the inferior steel plate and a previously polymerized layer of an intermediate material (either FF or VB) adhered to the upper steel plate. The composite resin was light-cured with a halogen lamp with light intensity of 500 mW/cm² for 60 s. A force/time graph was obtained for each sample for up to 120 s. Seven groups of 10 specimens each were evaluated: G1: Z-250; G2: FF; G3: VB; G4: Z-250 through a 0.5-mm layer of FF; G5: Z-250 through a 1-mm layer of FF; G6: Z-250 through a 0.5-mm of VB; G7: Z-250 through a 1-mm layer of VB. They were averaged and compared using one-way ANOVA and Tukey test at a = 0.05. The obtained contraction forces were: G1: 6.3N + 0.2N; G2: 9.8 + 0.2N; G3: 1.8 + 0.2N; G4: 6.8N + 0.2N; G5: 6.9N + 0.3N; G6: 4.0N + 0.4N and G7: 2.8N + 0.4N. The use of VB as an intermediate layer promoted a significant decrease in polymerization contraction force values of the restorative system, regardless of material thickness. The use of FF as an intermediate layer promoted an increase in polymerization contraction force values with both material thicknesses.

RESUMEN

The purpose of this study was to evaluate the individual contraction force during polymerization of a composite resin (Z-250), a flowable composite (Filtek Flow, FF) and a resin-modified glass ionomer cement (Vitrebond, VB), and the transmission of Z-250 composite resin polymerization contraction force through different thicknesses of FF and VB. The experiment setup consisted of two identical parallel steel plates connected to a universal testing machine. One was fixed to a transversal base and the other to the equipment's cross head. The evaluated materials were inserted into a 1-mm space between the steel plates or between the inferior steel plate and a previously polymerized layer of an intermediate material (either FF or VB) adhered to the upper steel plate. The composite resin was light-cured with a halogen lamp with light intensity of 500 mW/cm(2) for 60 s. A force/time graph was obtained for each sample for up to 120 s. Seven groups of 10 specimens each were evaluated: G1: Z-250; G2: FF; G3: VB; G4: Z-250 through a 0.5-mm layer of FF; G5: Z-250 through a 1-mm layer of FF; G6: Z-250 through a 0.5-mm of VB; G7: Z-250 through a 1-mm layer of VB. They were averaged and compared using one-way ANOVA and Tukey test at a = 0.05. The obtained contraction forces were: G1: 6.3N + 0.2N; G2: 9.8 + 0.2N; G3: 1.8 + 0.2N; G4: 6.8N + 0.2N; G5: 6.9N + 0.3N; G6: 4.0N + 0.4N and G7: 2.8N + 0.4N. The use of VB as an intermediate layer promoted a significant decrease in polymerization contraction force values of the restorative system, regardless of material thickness. The use of FF as an intermediate layer promoted an increase in polymerization contraction force values with both material thicknesses.

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Este artigo apresenta os aspectos práticos da odontologia legal na identificação de cadáveres através da arcada dentária, mostrando ao cirurgião-dentista alguns conceitos básicos que poderão contribuir na eventual necessidade de estar atuando em auxílio aos trabalhos de perícia

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Neste artigo foram descritos os vários fatores relacionados à bulimia nervosa, no que tange ao diagnóstico e, principalmente, ao tratamento, em função do envolvimento estético decorrente desta alteração patológica. Um caso clínico de bulimia nervosa foi descrito, enfatizando a importância e as vantagens do tratamento conservador, bem como os cuidados e passos operatórios para que os objetivos do mesmo sejam atingidos

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Se evaluó la filtración marginal en cavidades clase V restauradas con una aleación de amalgama con alto contenido de cobre, utilizando un barniz cavitario y un adhesivo. En 30 dientes extraídos se prepararon cavidades clase V sobre las caras vestibulares y se dividieron en tres grupos: grupo A: sin barniz cavitario, grupo B: Copalite y grupo C: Amalgambond Plus (Parkell). Todos los grupos fueron restaurados con una aleación de amalgama con alto contenido de cobre. las piezas fueron almacenadas en saliva artificial por 7 días a 37 grados C, luego termocicladas (5 grados C, 37 grados y 55 grados C) por 100 ciclos y sumergidas en una solución de azul de metileno durante 12 horas. Se efectuaron cortes longitudinales para la visualización bajo microscopio estereoscopio. Para la evaluación se clasificó en 4 grados; 0 ausencia de sustancia colorante, 1 presencia en el tercio superficial, 2 presencia en el tercio medio, 3 presencia en el tercio o pared axial. Los resultados fueron analizados a través de la prueba estadística Kruskall Wallis y U de Mann Whitney. Se concluyó que no existe diferencia estadísticamente significativa entre el Amalgambond Plus y Copalite, y ambos se comportaron mejor que el grupo control

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El propósito de este estudio fue evaluar la influencia del diseño cavitario sobre la microfiltración de restauraciones clase V con resina compuesta. Se utilizaron 20 molares humanos extraídos y se prepararon cavidades clase V en las caras bucal y lingual. Las cavidades del grupo A tenían una profundidad de 1 mm. y un largo de 4 mm. y las del grupo C y D una profundidad de 2 mm. y un largo de 2 mm. El ancho fue de 2 mm. para todos los grupos. Los grupos A, B y C fueron acondicionados con ácido maleico al 10 por ciento (gel etchant, Sotchbond MP) por 15 segundos, lavado, secado, se aplicó el imprimante (Primer, Scotchbond MP) y polimerizado por 10 segundos. Luego se aplicó la resina compuesta (Z-100) y se polimerizó por 40 segundos. Para el grupo D se aplicó el ionómero de vidrio (Vitrebond) por 30 segundos y se realizó la restauración como en los grupos A, B y C. Entre los grupos A y C se evaluó si existía influencia del volumen de resina compuesta, entre los grupos B y C si existía influencia del "factor de configuración" (superficie adherida/superficie libre) y entre los grupos C y D si existía influencia del uso del cemento de ionómero de vidrio como material de base. En los resultados no se encontraron diferencias estadísticamente significaticas entre ninguno de los grupos evaluados. No existió influencia del volumen de resina compuesta aplicada, la configuración de la cavidad y el uso del cemento de ionómero de vidrio como base en la microfiltración de restauraciones de clase V con resina compuesta

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