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Formulação de uma resina experimental e estudo das suas propriedades mecânicas e físico-químicas
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Abstract(s)
Objetivos: Avaliar e comparar a cinética de polimerização e a contração de polimerização de resinas compostas experimentais, formuladas com diferentes concentrações de prata coloidal (0, 0.5, 1 ou 2.5%), originando 4 resinas compostas experimentais.
Materiais e Métodos: Para o presente estudo foram preparadas resinas compostas experimentais contendo uma matriz de uretano dimetacrilato (UDMA) e dimetacrilato de polipropilenoglicol (PPGDMA), e uma fase inorgânica microhíbrida com aluminossilicatos de bário e sílica. À matriz orgânica foi adicionada prata coloidal líquida, variando a concentração em peso (0%; 0,5%; 1% e 2,5%). A cinética de polimerização foi investigada utilizando a técnica de reflexão atenuada com espectroscopia de Infravermelhos por Transformada de Fourier (ATR-FTIR). Discos de 2 x 10 mm foram preparados e colocados sobre o cristal de diamante do ATR. Os discos foram polimerizados por 20 s, utilizando um fotopolimerizador de luz LED com uma intensidade de saída de 1200 mW/cm². Espectros de FTIR foram adquiridos antes, durante e depois de 20 min da fotopolimerização utilizando o software de cinética
TimeBase (Perkin-Elmer, MA, EUA). As taxas de conversão extrapoladas, taxa de polimerização e tempo de semi-vida foram derivadas. A contração da polimerização foi medida seguindo o princípio de Arquimedes (n=3).
Resultados: A taxa de conversão e a taxa de polimerização diminuíram com o aumento da prata coloidal de 0 a 1% de concentração. Os resultados para a concentração de 2,5% não puderam ser analisados porque não houve suficiente polimerização. A semi-vida permaneceu a mesma para todas as formulações. A contração de
polimerização diminuiu de 3,3% para 2,1% com o aumento da prata coloidal de 0 para 2,5%.
Conclusões: Com base nos resultados, concluiu-se que uma concentração de prata coloidal de 0,5% foi a menos prejudicada no que toca às propriedades físico-químicas da resina composta, mantendo parâmetros de cinética e uma contração de polimerização aceitáveis.
Objectives: To evaluate and compare the polymerization kinetics and polymerization shrinkage of experimental composite resins, formulated with functional monomers with different concentrations by weight (0, 0.5, 1 or 2.5%), resulting in 4 experimental composite resins. Methods: For the present study, 4 experimental composite resins were prepared. The composite resins were formulated with a conventional organic matrix using monomers such as urethane dimethacrylate (UDMA) and polypropylene-glycol-dimethacrylate (PPGDMA). They were combined with a microhybrid inorganic phase containing barium aluminosilicate glasses and functional particles, varying the concentration by weight (0%; 0.5%; 1% and 2.5%).The polymerization kinetics were investigated using the attenuated reflectance technique with Fourier Transform Infrared spectroscopy (ATR-FTIR). Discs of 2 x 10 mm were prepared and placed on the ATR diamond crystal. The discs were polymerized for 20 s or 40 s using an LED light photopolymeriser with an output intensity of 1200 mW/cm². FTIR spectra were acquired before, during and after 20 min of photopolymerisation using TimeBase kinetics software (Perkin-Elmer, MA, USA). Extrapolated conversion rates, polymerisation rate and half-life time were calculated. Polymerization shrinkage (n=3) was measured following the Archimedes method. Results: The degree of conversion and polymerisation rate decreased with increasing colloidal silver from 0 to 1% concentration. The results for the 2.5% concentration could not be analysed for because there was insufficient polymerisation. The half-life remained the same for all formulations. Polymerization shrinkage decreased from 3.3% to 2.1% with increasing colloidal silver from 0 to 2.5%. Conclusions: Based on the results, it was concluded that a colloidal silver concentration of 0.5% was the least detrimental with regard to the physicochemical properties of the composite resin, maintaining kinetic parameters and an acceptable polymerisation shrinkage.
Objectives: To evaluate and compare the polymerization kinetics and polymerization shrinkage of experimental composite resins, formulated with functional monomers with different concentrations by weight (0, 0.5, 1 or 2.5%), resulting in 4 experimental composite resins. Methods: For the present study, 4 experimental composite resins were prepared. The composite resins were formulated with a conventional organic matrix using monomers such as urethane dimethacrylate (UDMA) and polypropylene-glycol-dimethacrylate (PPGDMA). They were combined with a microhybrid inorganic phase containing barium aluminosilicate glasses and functional particles, varying the concentration by weight (0%; 0.5%; 1% and 2.5%).The polymerization kinetics were investigated using the attenuated reflectance technique with Fourier Transform Infrared spectroscopy (ATR-FTIR). Discs of 2 x 10 mm were prepared and placed on the ATR diamond crystal. The discs were polymerized for 20 s or 40 s using an LED light photopolymeriser with an output intensity of 1200 mW/cm². FTIR spectra were acquired before, during and after 20 min of photopolymerisation using TimeBase kinetics software (Perkin-Elmer, MA, USA). Extrapolated conversion rates, polymerisation rate and half-life time were calculated. Polymerization shrinkage (n=3) was measured following the Archimedes method. Results: The degree of conversion and polymerisation rate decreased with increasing colloidal silver from 0 to 1% concentration. The results for the 2.5% concentration could not be analysed for because there was insufficient polymerisation. The half-life remained the same for all formulations. Polymerization shrinkage decreased from 3.3% to 2.1% with increasing colloidal silver from 0 to 2.5%. Conclusions: Based on the results, it was concluded that a colloidal silver concentration of 0.5% was the least detrimental with regard to the physicochemical properties of the composite resin, maintaining kinetic parameters and an acceptable polymerisation shrinkage.
Description
Dissertação para obtenção do grau de Mestre no Instituto Universitário Egas Moniz
Keywords
Fotopolimerização Resina composta Contração de polimerização Cinética de polimerização