Orientador: Angela Cristina Cilense Zuanon / Banca: Rosana de Fátima Possobon / Banca: Lourdes Santos Pinto / Resumo: O objetivo deste trabalho, dividido em tres estudos, foi avaliar: (1) a influencia da utilizacao de diferentes fontes de luz e metodos de fotoativacao sobre o grau de conversao e a contracao de polimerizacao de uma resina composta nanoparticulada; (2) a influencia da utilizacao dos diferentes metodos de fotoativacao, disponibilizados por aparelhos LED de 2a geracao, sobre a contração volumetrica das resinas compostas microhibrida e nanoparticulada e (3) as propriedades termicas e o grau de conversao das resinas compostas microhibrida e nanoparticulada, submetidas aos diferentes metodos de fotoativacao disponibilizados por aparelhos LED de 2a geracao. No primeiro estudo, o grau de conversao (GC) foi avaliado pelo metodo da espectroscopia infravermelha transformada de Fourier (FT-IR) e as forcas de contracao (C) mensuradas em maquina de ensaios universal (EMIC). Os dados obtidos para o GC e C foram analisados estatisticamente pelo teste da analise de variancia (ANOVA), sendo que para as forcas de contracao, a correcao de Welch e o teste Tamhane também foram empregados. No segundo estudo, a contracao volumetrica foi avaliada por um mecanismo de video e imagem (AcuvolR/Bisco) e os dados obtidos foram analisados estatisticamente pelos testes ANOVA e Tukey. No terceiro estudo, o metodo da calorimetria exploratoria diferencial foi empregado para avaliar a temperatura de transicao vitrea (Tg) e de degradacao dos materiais e o GC por FTIR. Os dados relativos ao GC foram analisados estatisticamente pelos testes ANOVA e Tukey. Os resultados demonstraram diferencas na contracao de polimerizacao de acordo com o metodo de fotoativacao empregado. No primeiro e segundo estudos, mesmo empregando diferentes metodologias, o metodo de fotoativacao continuo apresentou os maiores valores de contracao. Por outro lado,o GC nao foi influenciado pelo método... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this work, divided into three studies, was evaluate: (1) the influence of different light sources and photo-activation methods on degree of conversion and polymerization shrinkage of a nanocomposite resin; (2) the influence of different photo-activation methods, available by the 2nd generation LED light-curing units, on the volumetric shrinkage of microhybrid and nanocomposite resins and (3) thermal properties and degree of conversion of microhybrid and nanocomposite resins submitted to different photo-activation methods available by 2nd generation LED light-curing units. In the first study, degree of conversion (DC) was evaluated by Fourier transform infrared spectroscopy (FT-IR) and shrinkage forces (S) were measured in a universal testing machine (EMIC). The data obtained for DC and S were analyzed by Analysis of Variance test (ANOVA) and for S Welch's correction and Tamhane's tests were also employed. In the second study, volumetric shrinkage was evaluated by video-imaging device (AcuvolR/Bisco) and data were analyzed by ANOVA and Tukey's test. In the third study, differential scanning calorimetry was used in order to observe glass transition temperature (Tg) and degradation peak of the materials and DC was evaluated for FT-IR. The DC data were analyzed by ANOVA and Tukey's test. The results showed differences in the polymerization shrinkage according to photo-activation method employed. In the first and second studies, the continuous photo-activation methods presented the highest values for shrinkage even though different methodologies were used to assess. Moreover, DC was not influenced by the photo-activation method but was influenced by light sources. The lowest DC values were observed for halogen light-curing unit. In the second study beyond the influence of the photo-activation method on the volumetric shrinkage... (Complete abstract click electronic access below) / Mestre