title: Influence of different shades and LED irradiance on the degree of conversion of composite resins.
abstract: The aim of this study was to evaluate the degree of conversion (DC) of two composite resins with different shades that were light cured by light-emitting diodes (LEDs) of different irradiances. Specimens (5 mm ' 2 mm) were prepared with a nanofilled (Filtek Supreme - A2E, A2D, and WE) or microhybrid resin (Opallis - A2E, A2D, and EBleach Low) and were randomly divided into 12 groups (n = 5 each) according to the composite resin and light-curing unit (Elipar FreeLight 2, 1250 mW/cm²; Ultralume 5, 850 mW/cm²). After 24 h, the DC was measured on two surfaces (top and bottom) with Fourier Transform infrared spectroscopy (FTIR). Data were statistically analyzed with two-way ANOVA and Tukey test (a = 0.05). Statistical differences among the surfaces were observed in all experimental conditions, with higher values on the top surface. The microhybrid resin presented the highest DCs for shades A2E and A2D on the top surface. The LED with higher irradiance promoted better DCs. Taken together, the data indicate that the shade of a composite resin and the irradiance of the light source affect the monomeric conversion of the restorative material.
authors.affiliation: Department of Restorative Dentistry, Operative Dentistry Area, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Lívia Aguilera
authors.initials: LA
authors.lastname: Gaglianone
authors.forename: Adriano Fonseca
authors.initials: AF
authors.lastname: Lima
authors.forename: Larissa Sgarbosa Napoleão de
authors.initials: LS
authors.lastname: Araújo
authors.forename: Andrea Nóbrega
authors.initials: AN
authors.lastname: Cavalcanti
authors.forename: Giselle Maria
authors.initials: GM
authors.lastname: Marchi
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D055117:Curing Lights, Dental; D008027:Light; D008422:Materials Testing; D044367:Phase Transition; D058105:Polymerization; D011897:Random Allocation; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins