title: Effect of light-activation methods and water storage on the flexural strength of two composite resins and a compomer.
abstract: The present study evaluated the flexural strength of three composite resins recommended for direct esthetic restorations: a polyacid modified composite (Dyract AP), a unimodal composite resin (Filtek Z250) and a hybrid composite resin (Point 4). The variation factors, apart from the type of composite resin, were the light activation method and the water storage period. The composite resins were light-cured in continuous mode (40 s, 500 mW/cm2) or in ramp mode (0-800 mW/cm2 for 10 s followed by 30 s at 800 mW/cm2) and stored for 24 hours or 30 days in distilled water at 37 degrees C. The data were analyzed by ANOVA and Tukey test for multiple comparisons (alpha = 0.05). The composite resin Z250 presented the highest mean flexural strength (166.74 MPa) and Dyract AP presented the lowest one (129.76 MPa). The storage for 30 days decreased the flexural strength in ramp mode (24 h: 156.64 MPa; 30 days: 135.58 MPa). The light activation method alone did not lead to different flexural strength values.
authors.affiliation: Department of Dental Materials, School of Dentistry, University of São Paulo.
authors.forename: Leonardo Eloy
authors.initials: LE
authors.lastname: Rodrigues Filho
authors.forename: Luis Antônio dos Santos
authors.initials: LA
authors.lastname: Burger
authors.forename: Silvia
authors.initials: S
authors.lastname: Kenshima
authors.forename: José Roberto de Oliveira
authors.initials: JR
authors.lastname: Bauer
authors.forename: Igor Studart
authors.initials: IS
authors.lastname: Medeiros
authors.forename: Antonio
authors.initials: A
authors.lastname: Muench
mesh_terms: D000704:Analysis of Variance; D020770:Compomers / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D004548:Elasticity; D008027:Light; D008422:Materials Testing; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D020770:Compomers; D003188:Composite Resins; D014867:Water