A critical analysis of the degree of conversion of resin-based luting cements

Abstract

ObjectiveThis study analyzed the degree of conversion (DC%) of four resin-based cements (All Ceram, Enforce, Rely X ARC and Variolink II) activated by two modes (chemical and dual), and evaluated the decrease of DC% in the dual mode promoted by the interposition of a 2.0-mm-thick IPS Empress 2 disc.Material and MethodsIn the chemical activation, the resin-based cements were prepared by mixing equal amounts of base and catalyst pastes. In the dual activation, after mixing, the cements were light-activated at 650 mW/cm2 for 40 s. In a third group, the cements were lightactivated through a 2.0-mm-thick IPS Empress 2 disc. The DC% was evaluated in a FT-IR spectrometer equipped with an attenuated total reflectance crystal (ATR). The data were analyzed by two-way ANOVA and Tukey's HSD test.ResultsFor all resin-based cements, the DC% was significantly higher with dual activation, followed by dual activation through IPS Empress 2, and chemical activation (p<0.05). Irrespective of the activation mode, Rely X presented the highest DC% (p<0.05). Chemically activated Variolink and All Ceram showed the worst results (p<0.05). The DC% decreased significantly when activation was performed through a 2.0-mm-thick IPS Empress 2 disc (p<0.05).ConclusionsThe results of the present study suggest that resin-based cements could present low DC% when the materials are dually activated through 2.0 mm of reinforced ceramic materials with translucency equal to or less than that of IPS-Empress 2.

Influence of the interposition of ceramic spacers on the degree of conversion and the hardness of resin cements

“…A similar method (with thin films of the individual pastes) has been described in the literature, but there was not much information on how the data was dealt with. 26 Furthermore, other studies comparing these two protocols were not found.…”

Influence of curing mode of resin luting cements on bond strength to dentin

“…The clinical longevity of these restorations is dependent of the cavity design, the indirect restorative material, the properties of the RC and cementation technique selected 9 . The most common tests for resin-ceramic bonding measurements are shear and tensile bond strength tests 3 .…”

“…The overall properties of RC using the dual-cure system seem to be superior when compared to the single-cure system 19 . Noronha Filho et al 9 (2010) observed that RC present low degree of conversion when the indirect restoration material attenuates the light activation. The dual curing RC has been developed to overthrown these conditions 20 .…”

Influência das unidades fotoativadoras e do material restaurador indireto sobre a dureza de um cimento resinoso dual auto-adesivo e um cimento resinoso dual convencional por meio de teste de nanoendentação

“…Durante esse processo, as ligações duplas de carbono (C=C) existentes na porção alifática da cadeia são quebradas e convertidas em ligações covalentes (C-C) entre os monômeros metacrilatos, formando a cadeia polimérica (Noronha-Filho et al, 2010).…”

“…Estudos demonstraram que vários fatores podem interferir na eficácia da polimerização do cimento empregado na cimentação de restaurações indiretas em cerâmica ou resina composta: a composição, espessura, opacidade e a cor do material restaurador podem atenuar a passagem da fonte de luz e, consequentemente, diminuir a porcentagem de polimerização do cimento (Fonseca, 2004;Soares et al, 2006;Borges et al, 2008;Hickel, 2008;Meng et al, 2008;Pazin et al, 2008;Hooshmand et al, 2009, Noronha-Filho et al, 2010Valentino et al, 2010 O sucesso clínico de um procedimento restaurador indireto depende de inúmeros fatores e entre eles, a técnica de cimentação usada que cria um link entre a restauração e o dente (Radovic et al, 2008;Souza et al, 2011). Para a seleção de um agente de cimentação ideal, vários fatores devem ser considerados, incluindo suas propriedades físico-químicas, a técnica de uso e o planejamento clínico.…”