Profundidade de polimerização de um compósito à base de silorano ativado por diferentes fontes de luz

• Ano de defesa: 2010
• Autor(a) principal: Silverio de Almeida Souza Torres
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Resinas compostas; Restauração dentária permanente métodos; Cura luminosa de adesivos dentários/utilização; Compositos poliméricos; Polimerização; Resinas de silorano; Restauração dentária permanente/métodos
• Link de acesso: http://hdl.handle.net/1843/ZMRO-8EDJHV

The depth cure of a composite can be analyzed by evaluating the mechanical properties such as hardness and flexural strenght or by the degree of conversion which in turn can be measured by spectroscopy (FTIR and RAMAN), nuclear magnetic resonance (NMR); and thermal analysis as the differential scanning calorimetry (DSC) and thermal or dynamic-mechanical analyses. Recently, a composite based in silorane monomer was available on the market. When we refer to dental polymers, this type of monomer provides a distinct polymerization process (cationic ring-opening system), changing also the way of measuring the degree of conversion. The purpose of this study was to investigate the depth of cure, assessed for Fourier transform infrared spectroscopy (FTIR) and microhardness Knoop (HK) in the silorane based composite Filtek P90/3M-ESPE (FP90). An experimental study, in vitro, delineated in randomized complete blocks (Blocks A, B, C, D), where the factors under studied were the light curing units (LCUs) in three levels: Radii-cal/SDI (R), Bluephase G2/ Ivoclar-Vivadent (BP) and Optilux 501/SDS-kerr (OP) and the curing depth of four levels (2, 3, 4 and 5 mm), was conducted. The experimental units were specimens (n = 4) made with FP90 from an array of nylon with the center hole of 5mm in diameter previously sectioned into four depths. The degree of conversion in the polymerization process was based on the extent of the decrease in relative intensity of the stretching band "C-O-C" oxirane rings in 883 cm-1, when the monomer is converted to polymer. The normalization standard used was a band related to stretching vibrations of C-H "located at 2919 cm-1. For the tests of microhardness (KH) were used a load of 50g for a period of 50 seconds. The data were subjected to Levene and Barllet tests for the verification of normality and homoscedasticity. Considering the results of Bartlett and Levene tests, the graphs of normal curves and the n = 4, the nonparametric Friedmans test was used to study the effect of each factors alone. There was no effect of LCUs on the DC (p = 0.472) and KH (p = 0.174) for the studied depths. The Friedmans test showed significant effect of depth on the DC (p = 0.007; dms = 7.96) and was significantly higher in the depth of 2mm [72,85(65,71-78,66)]compared to depths of 4mm [40,78(10,27-56,86)] and 5mm [21,15(7,08-31,34)]. The Friedmans test also showed significant effect of depth on KH (p = 0.007; dms = 7.96). The KH was significantly higher at depth 2 mm [41,76(39,98-41,82)] compared to depths of 4mm [33,09(20,11-34,74)] and 5mm [20,23(10,22-24,81)]. Spearman's analysis found a positive linear correlation between the variables KH and DC for Filtek P90/3M-ESPE (r=0,858; p<0,000). This study concluded that although theeffect of polymerization units have not been verified in this study, the values of DC and KH for silorane based composite Filtek P90/3M-ESPE decreased with depth, maintaining satisfactory to a depth of 2mm