Influence of BisGMA, TEGDMA, and BisEMA contents on viscosity, conversion, and flexural strength of experimental resins and composites

Abstract

Different monomer structures lead to different physical and mechanical properties for both the monomers and the polymers. The objective of this study was to determine the influence of the bisphenylglycidyl dimethacrylate (BisGMA) concentration (33, 50 or 66 mol%) and the co-monomer content [triethylene glycol dimethacrylate (TEGDMA), ethoxylated bisphenol-A dimethacrylate (BisEMA), or both in equal parts] on viscosity (eta), degree of conversion (DC), and flexural strength (FS). Eta was measured using a viscometer, DC was obtained by Fourier transfer Raman (FT-Raman) spectroscopy, and FS was determined by three-point bending. At 50 and 66% BisGMA, increases in eta were observed following the partial and total substitution of TEGDMA by BisEMA. For 33% BisGMA, eta increased significantly only when no TEGDMA was present. The DC was influenced by BisGMA content and co-monomer type. Mixtures containing 66% BisGMA showed a lower DC compared with mixtures containing other concentrations of BisGMA. The BisEMA mixtures had a lower DC compared with the TEGDMA mixtures. The FS was influenced by co-monomer content only. BisEMA mixtures presented a statistically lower FS, followed by TEGDMA + BisEMA mixtures, and then by TEGDMA mixtures. Partial or total replacement of TEGDMA by BisEMA increased eta, which was associated with the observed decreases in DC and FS. Although the BisGMA content influenced the DC, it did not affect the FS results.

Hydrolytic degradation of a resin composite as a function of the curing tip distance and aging

“…New formulations of monomers were developed by modifying the chemical structure of certain monomers and/or replacing them. The structure of BisEMA is nearly identical to that of BisGMA, aside from the absence of hydroxyl groups 5 . Replacing BisGMA with BisEMA in composites containing TEGDMA resulted in a higher conversion but no improvement in flexural and diametral tensile strengths 41 .…”

“…Replacing BisGMA with BisEMA in composites containing TEGDMA resulted in a higher conversion but no improvement in flexural and diametral tensile strengths 41 . Another study 5 also demonstrated that mixtures of BisGMA and TEGDMA present an increased crosslink density and a higher degree of conversion than what is observed for mixtures of BisGMA and BisEMA. The lower molecular weight of TEGDMA and the synergic effect with BisGMA have been explained to influence the kinetic parameters contributing to a higher conversion.…”

“…In these instances, a reduced monomer conversion may occur. Resin conversion is an essential component to ensuring optimal mechanical properties that resist mechanical and chemical deterioration 5,6 . Depending on the clinical scenario, the amount of light that penetrates the bulk material can be attenuated or scattered; as a consequence, fewer molecules of camphorquinone are activated, reducing the extent of the reaction and also limiting the depth of the cure 7 .…”

“…Composite composition determines the hydrophilicity, mobility and kinetic parameters 5 . The BisGMA monomer contains pendant hydroxyl groups within its molecular backbone 20 .…”

Estudo de propriedades de resinas compostas bulk fill

“…Estudos têm relacionado a resistência à flexão ao conteúdo de carga 12,20,34,39,84,95 , dureza e módulo de elasticidade 98 , podendo ser influenciada por variáveis como conteúdo da matriz resinosa 39,99 , grau de conversão 100 , distância do material à fonte de luz 95 , quantidade de monômeros não reagidos 71 , temperatura da reação 42 e tratamentos secundários de cura 71,74,88,93,94 . Entretanto, um dos fatores mais importantes para o aumento na resistência do material parece estar relacionado à adesão entre a matriz orgânica e a fase inorgânica e à transferência da tensão gerada da matriz polimérica para as partículas de carga 39 .…”