ABSTRACT
This study evaluated selected structural and physical properties, such as degree of conversion (DC), Vickers hardness (VHN), and compression strength (CS), of three new dual-cure bulk-fill resin-based composites (RBCs; ACTIVA, HyperFIL, and Fill-Up) and compared them to those of a conventional RBC (Filtek Z250) at three clinically relevant depths. Samples (n=180) were prepared in three depths (2,4, and 6mm). Fourier-transform infrared spectroscopy (FTIR) analysis and VHN and CS tests were performed. The DC value was calculated by considering the relative change in the aliphatic C=C peaks. The fractured surfaces of representative samples were characterized using scanning electron microscopy (SEM). Data were statistically evaluated using two-way analysis of variance and post hoc Bonferroni tests (p<0.05). According to the VHN results, Filtek Z250 showed the highest bottom/top hardness ratio (97.94±1.01) at 2mm thickness and ACTIVA showed the lowest bottom/top hardness ratio (43.48±5.64) at 6mm thickness (p<0.001). According to the FTIR results, the DC decreased with increasing thickness in all materials (p<0.05). Filtek Z250 showed the highest (301±12.4 MPa) and ACTIVA exhibited the lowest (232±17.2 MPa) CS values at 2mm thickness (p<0.05). The lowest CS values were obtained for ACTIVA, and the highest values were obtained for Filtek Z250 for samples with thicknesses of 4 and 6mm, respectively (p<0.05). The structural features of restorative composites, such as the resin chemistry and filler type and content, and the operational parameters (i.e., material thickness and curing conditions) strongly affect crosslinking reactions and thus the DC, VHN, and CS values.
Este estudio evaluó propiedades físicas y estructurales, como el grado de conversión (DC), la dureza Vickers (VHN) y la resistencia a la compresión (CS), de tres nuevos compósitos a base de resina de curado dual tipo bulk (RBC; ACTIVA , HyperFIL y Fill-Up) y los comparó con los de una resina compuesta convencional (Filtek Z250) en tres profundidades clínicamente relevantes. Se prepararon muestras (n=180) en tres profundidades (2,4 y 6mm). Se realizaron análisis de espectroscopia infrarroja por transformada de Fourier (FTIR) y pruebas VHN y CS. El valor de DC se calculó considerando el cambio relativo en los picos alifáticos C=C. Las superficies fracturadas de muestras representativas se caracterizaron mediante microscopía electrónica de barrido (MEB). Los datos se evaluaron estadísticamente mediante análisis de varianza de dos vías y pruebas post hoc de Bonferroni (p<0,05). De acuerdo con los resultados de VHN, Filtek Z250 mostró la relación de dureza inferior/superior más alta (97,94±1,01) con un espesor de 2mm y ACTIVA mostró la relación de dureza inferior/superior más baja (43,48±5,64) con un espesor de 6mm (p<0,001). De acuerdo con los resultados de FTIR, la DC disminuyó al aumentar el espesor en todos los materiales (p<0,05). Filtek Z250 mostró los valores de CS más altos (301±12,4 MPa) y ACTIVA los más bajos (232±17,2 MPa) a 2mm de espesor (p<0,05). Los valores más bajos de CS se obtuvieron para ACTIVA y los valores más altos para Filtek Z250 para muestras con espesores de 4 y 6mm, respectivamente (p<0,05). Las características estructurales de las resinas compuestas de restauración, como la química; además del tipo y contenido del relleno, y los parámetros operativos (es decir, el espesor del material y las condiciones de curado) afectan en gran medida las reacciones de interacción química y, por lo tanto, los valores de DC, VHN y CS.
Subject(s)
Microscopy, Electron, Scanning , Composite Resins/analysis , Compressive StrengthABSTRACT
Objetivo: Avaliar o efeito de dois compósitos, de diferentes matrizes poliméricas, e da técnica de fotoativação, sobre a resistência à fratura, por compressão, de pré-molares superiores com restaurações de classe II. Materiais e Métodos: Cavidades MOD foram preparadas em 56 pré-molares superiores, simulando tratamentos endodônticos. Os dentes foram divididos em quatro grupos (n=14): G1 - fotoativação convencional, restauração com Filtek Z350XT (3M ESPE) e adesivo Adper Single Bond 2 (3M ESPE); G2 - fotoativação pulso tardio, restauração Filtek Z350XT e adesivo Adper Single Bond2; G3 - fotoativação convencional, restauração Filtek P90 (3M ESPE) e adesivo próprio da Filtek P90 (3M ESPE); e G4 - fotoativação pulso tardio, restauração Filtek P90 e adesivo próprio da Filtek P90. No G1 e G3 (fotoativação convencional), a aplicação de compósito foi em incrementos de 2 mm, cada incremento fotoativado por 40 segundos, com aparelho LED, intensidade de 500 mW/cm2, aferida com radiômetro (Demetron). No G2 e G4 (fotoativação por pulso tardio) aplicação de compósito também foi com incrementos de 2mm, porém, cada incremento fotoativado, inicialmente durante 5s., com 300 mW/cm2. Após um período de 5 minutos foi realizada fotoativação, por 40s., intensidade de 500 mW/cm2. A fotoativação foi repetida para cada incremento. Após 24 horas, os espécimes foram polidos e submetidos ao teste de compressão, com ponta ativa de formato cilíndrico/arredondado (Instron-0,5mm/ min). Para análise estatística foi usado ANOVA 2 e Teste de Tukey (p > 0,05). Resultados: Os valores médios (newtons) foram: G1 - 1157,98 (±444,62); G2 - 1404,14 (±391,82); G3 - 1255,30 (±422,34); e G4 - 1213,76 (±419,95). A resistência à fratura, por compressão, dos pré-molares com restaurações MOD foi estatisticamente similar nos quatro grupos avaliados. Conclusão: Não foram verificadas diferenças significativas relacionadas aos dois compósitos, com diferentes matrizes poliméricas e diferentes métodos de fotoativação.(AU)
Aim: To evaluate the effect of two composite resins of different polymeric matrices and the photoactivation technique as regards fracture resistance by, compression of maxillary pre-molars with Class II restorations. Materials and Methods: MOD cavities were prepared in 56 premolars, simulating endodontic treatments. The teeth were divided into four groups (n=14): G1: conventional photoactivation, restoration with Filtek Z350XT (3M ESPE) and adhesive Adper Single Bond 2 (3M ESPE); G2: Pulse delay photoactivation, restoration with Filtek Z350XT and adhesive Adper Single Bond 2; G3: conventional photoactivation, restoration with Filtek P90 (3M ESPE) and self-adhesion of Filtek P90 (3M ESPE); and G4: pulse delay photoactivation, restoration with Filtek P90 and self-adhesion of Filtek P90. In G1 and G3 (conventional photoactivation), the composite resin was applied at 2 mm increments, each of which was light cured for 40 seconds, using a LED unit, at an intensity of 500 mw/cm2, measured with a radiometer (Demetron). In G2 and G4 (pulse delay photoactivation), the composite resin was also applied at 2 mm increments; however, each increment was initially photoactivated for 5 seconds at 300 mw/cm2. After a period of 5 minutes, a new photoactivation was performed for 40 seconds at an intensity of 500 mw/cm2. The photoactivation was repeated for each increment. After 24 hours, the specimens were polished and tested for compression, with cylindrical/round active tip (Instron - 0.5 mm/ min). The ANOVA 2 and Tukey tests were used for statistical analyses (p > 0.05). Results: Mean values (Newtons) were as follows: G1: 1157.98 (±444.62); G2: 1404.14 (±391.82); G3: 1255.30 (±422.34); and G4: 1213.76 (±419.95). The resistance to fracture by compression of the pre-molars with MOD restorations proved to be statistically similar in the four evaluated groups. Conclusion: No significant differences could be observed regarding the two composite resins with different polymeric matrices and the different photoactivation methods.(AU)
Subject(s)
Composite Resins , Compressive Strength , Polymerization , BicuspidABSTRACT
Este estudio tuvo como objetivo analizar el efecto del envejecimiento artificial acelerado (EAA) sobre la resistencia a compresión de las resinas compuestas Filtek Z-250 (F), Charisma (C), Durafil VS (D), Supreme para cuerpo (SNc) e Supreme translúcido (SNt). Fueron confeccionados 16 especímenes con cada resina compuesta con dimensiones de 4x8mm. Las resinas fueron inseridas en tres incrementos y sobre el último incremento fue colocada una matriz de poliéster y una lamina de vidrio con la finalidad obtener una superficie regular. Cada incremento fue polimerizado con una intensidad de luz entre 580 y 600 mW/cm², la cual era monitoreada con un radiómetro (Gnatus) durante todo el tiempo de utilización. Veinticuatro horas después de la obtención de las muestras, 8 muestras de cada material fueron sometidas a los ensayos de compresión (grupo control) los cuales fueron realizados en una maquina EMIC DL 2000, con una célula de carga de 2000Kgf y velocidad de 0,5mm/min. Las otras 8 muestras de cada material fueron colocados en la máquina de EAA, las cuales permanecieron durante 196 horas, las mismas que equivalen a 5 años de envejecimiento y enseguida sometidos a los ensayos de compresión. Los resultados, fueron sometidos al ANOVA y test de Tukey (p<0,05) los cuales mostraron que las resinas SNt y D, no tuvieron diferencias estadísticas cuando fueron comparadas después de 24h y del EAA; las demás resinas mostraron resultados EAA>24h. Se pudo concluir que el envejecimiento artificial acelerado aumento la resistencia a compresión de las resinas F, C e SNc.
The aim of this study was to analyze the effect of artificially accelerated aging (AAA) on the resistance to compression of resin composites Filtek Z-250 (F), Charisma (C), Durafill VS (D), Supreme for body (SNC) and Supreme Translucent (SNt). Sixteen test specimens measuring 4 x 8 mm were made of each resin composite. The resins were inserted in three increments, and on the last of them, a polyester strip and glass slide were placed for the purpose of obtaining a regular surface. Each increment was polymerized by light intensity of 580 to 600 mw/cm², which was monitored with a radiometer (Gnatus) throughout the time of use. Twenty-four hours after the samples were obtained, 8 specimens of each material were submitted to the compression test (Control Group) performed with an EMIC DL 2000, machine, with a 2000 Kgf load cell at a speed of 0.5 mm/min. The other 8 samples of each material were placed in an AAA machine, and remained there for 196 hours, equivalent to 5 years of aging. Next they were submitted to the compression test. The values were submitted to ANOVA and the Tukey test (p<0.05). The results showed that for resins SNt and D there were no statistically significant differences when compared at 24h and after AAA; the other resins showed results of AAA>24h. It was concluded that artificially accelerated aging increased the resistance to compression of the resin composites F, C and SNc.
ABSTRACT
Objective:To compare the compression strength of three provisional restorative materials. Methods:Eighteen cylinder specimens were fabricated with 12mm in diameter and 30mm in height according to the GB/T 7314-2005 standards. Six specimens were made of self-curing resin,Switf-Temp and Protemp Ⅱ respectively. Then all specimens were compressively loaded and the data were recorded by MTS880 testing machine. Results:There were significantly statistical differences (P0.05)in terms of compression strength. Conclusion:The self-curing resins have higher compression strength than those of Switf-Temp and Protemp Ⅱ. The dentists must be aware of different situations of teeth and choose the provisional material appropriate for each tooth.