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  • Title: Network structures of Bis-GMA/TEGDMA resins differ in DC, shrinkage-strain, hardness and optical properties as a function of reducing agent.
    Author: Furuse AY, Mondelli J, Watts DC.
    Journal: Dent Mater; 2011 May; 27(5):497-506. PubMed ID: 21388670.
    Abstract:
    OBJECTIVES: To evaluate the influence of different tertiary amines on degree of conversion (DC), shrinkage-strain, shrinkage-strain rate, Knoop microhardness, and color and transmittance stabilities of experimental resins containing BisGMA/TEGDMA (3:1wt), 0.25wt% camphorquinone, 1wt% amine (DMAEMA, CEMA, DMPT, DEPT or DABE). Different light-curing protocols were also evaluated. METHODS: DC was evaluated with FTIR-ATR and shrinkage-strain with the bonded-disk method. Shrinkage-strain-rate data were obtained from numerical differentiation of shrinkage-strain data with respect to time. Color stability and transmittance were evaluated after different periods of artificial aging, according to ISO 7491:2000. Results were evaluated with ANOVA, Tukey, and Dunnett's T3 tests (α=0.05). RESULTS: Studied properties were influenced by amines. DC and shrinkage-strain were maximum at the sequence: CQ<DEPT<DMPT≤CEMA≈DABE<DMAEMA. Both DC and shrinkage were also influenced by the curing protocol, with positive correlations between DC and shrinkage-strain and DC and shrinkage-strain rate. Materials generally decreased in L* and increased in b*. The strong exception was the resin containing DMAEMA that did not show dark and yellow shifts. Color varied in the sequence: DMAEMA<DEPT<DMPT<CEMA<DABE. Transmittance varied in the sequence: DEPT≈DABE<DABE≈DMPT≈CEMA<DMPT≈CEMA≈DMAEMA, being more evident at the wavelength of 400nm. No correlations between DC and optical properties were observed. SIGNIFICANCE: The resin containing DMAEMA showed higher DC, shrinkage-strain, shrinkage-strain rate, and microhardness, in addition to better optical properties.
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