ABSTRACT
This study evaluated the influence of packing forces on the flexural strength of three packable and one hybrid composite. A metallic stardard mold was used to prepare 12 specimens from each packable composite (ALERT, Solitaire and Surefil) and a hybrid composite (Filtek Z250), divided in two packing forces (7.4 N and 17.2 N). The specimens were light cured for 40 seconds, being immersed in distilled water for seven days. Flexural strength was measured on a testing machine; at a crosshead speed of 0.5 mm/minutes. Data were analyzed using parametric statistical tests. Materials exhibited statistically significant differences (p<0.05): Surefil = Filtek Z250 > ALERT > Solitaire. No statistical differences in flexural strength were found between the packing forces and the interaction. It was conclued that packing forces do not affect flexural strength of tested composites, and packable composites had similar or lower flexural strength than a hybrid composite.
Subject(s)
Composite Resins , In Vitro Techniques , Shear Strength , Stress, Mechanical , Compomers , Condensation , Dental MaterialsABSTRACT
O objetivo deste estudo foi avaliar a resistência flexural (FS) e o môdulo de elasticidade (ME) de três resinas micro-híbridas (Filtek Z250; Charisma; P60) e uma submicrohibrida (Concept) utilizando LED ou polimerização por luz halógena. Vinte espécimes (25x2x2 mm) de cada resina composta foram confeccionados e polimerizados usando LED ou luz halógena e posteriormente armazenados em água destilada a 37º C ± 1 durante 30 dias. Testes de FS e ME foram realizados em uma máquina de ensaio universal Instron (0.75mm/min). ANOVA e comparações múltiplas (SNK) mostraram que os dois sistemas de polimerização não apresenrtaram diferenças significantes (p>0.05) para a FS da Charisma e Filtek Z250. Os dois métodos de polimerização também produziram resultados similares para o ME da Charisma, Concept e Filtek Z250. Diferenças significantes de FS e ME foram encontradas com o sistema halógeno, apresentando melhores resultados que o sistema LED. As diferenças significativas na resistência flexural e módulo de elasticidade sempre apontaram uma superioridade para o sistema de luz halógena em comparação ao LED.
Subject(s)
Composite Resins , Elasticity , Light/adverse effects , Materials Testing , Pliability , Analysis of VarianceABSTRACT
This study aimed to evaluate the flexural strength and elastic modulus of indirect composite resins compared with direct composite resin. Two indirect composite resins (Artglass, AR and Belle Glass HP, BE) and one direct composite resin (Filtek Z250, Z2) were tested. Fifteen standard specimens (25x2x2mm) were prepared for each material. Z2 was polymerized using a XL 3000 light curing unit with energy higher than 450 mW/cm² for 40 seconds. The AR was photopolymerized with intense pulsed visible ligth during 180 seconds, at 520 nm/20 Hz. BE was photopolymerized during 60 seconds at 500 nm and post-cured at 138°C, under pressure, in a nitrogen atmosphere for 20 minutes. The specimens were stored in distilled water at 37°C for seven days and, then, subjected to FS and EM tests, using a universal testing machine. One-way analysis of variance and Tukey's test were used. The mean flexural values (MPa) were: AR = 126.8 ± 16.8; BE = 145.2 ± 14.3; Z2 = 140.0, without significant differences (p>0.05). Significant differences (p<0.01) were observed regarding elastic modulus, as follow: BE (15.1 ± 1.7) > Z2 (9.6 ± 1.5) > AR (7.5 ± 1.0). Within the limitations of the study, it was concluded that significant differences were only observed for elastic modulus, with the direct material exhibiting lower values.