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Curing Quality of Composites as Influenced by the Filler Content, Light Source and Curing Time

Boniek Castillo Dutra Borges*,Ana Isabelle Salvador Groninger,Giulliana Panfiglio Soares,Cláudia Batitucci dos Santos-Daroz,Gláucia Maria Bovi Ambrosano,Gisele Maria Marchi,Maria Cec�lia Caldas Giorgi,Flávio Henrique Baggio Aguiar

The quality of composite polymerization has been of great concern for researchers. Curing of nanocomposites under long distance (8 mm) and extended light exposure through conventional (halogen and LED) and argon laser lamps is unclear in the literature. This study evaluated the influence of curing modes and filler particle size on hardness and degree of conversion of dental composites photo activated at an 8 mm distance. Light sources (LED 1100 mW/cm2-Bluephase; LED 700 mWcm2-Ultra-lume; halogen lamp 450 mW/cm2-XL3000; and argon-laser 500 mW/cm2-AccuCure), curing times (20 and 60 s), microhybrid (Filtek-Z250) and nanofilled (Filtek-Supreme) resins were investigated. Eighty samples (n=5) were made using Teflon molds. Hardness and degree of conversion were obtained for bottom/top surfaces of 2-mm increments. Data were submitted to ANOVA and Tukey tests (?=5%).Top surfaces showed similar hardness. A 60s exposure time increased bottom hardness and Filtek-Z250 showed higher hardness for curing units except Bluephase. Regarding degree of conversion, bottom/top surfaces showed similar means at 60s; at 20s, bottom/top surfaces revealed similar means only for Filtek-Z250 cured by Bluephase and Ultra-lume. High irradiance and extended exposure time can improve hardness and conversion on bottom surface. Microhybrid resin presented better conversion of monomers than the nanofilled composite under higher irradiance and extended exposure times.