Influence of Photoinitiator on Accelerated Artificial Aging and Bond Strength of Experimental Resin Cements

Abstract

The goal of this study was to evaluate in vitro the effect of the photoinitiator phenylpropanedione (PPD), alone or combined with camphorquinone (CQ), on color stability of photoactivated resin cements and their bond strength to ceramics using a micro-shear test. Four resin cements were used: a commercial brand cement (RelyX Veneer®) and 3 experimental cements with different types and concentration of photoinitiators. For color analysis, ceramic discs were cemented on bovine dentin specimens to simulate indirect restorations (n=8) and were exposed to UV for 120 h and tested for color alteration using a reflectance spectrophotometer and the CIEL*a*b* system. Data were analyzed by Anova and Tukey's test at 5% significance level. The color test results did not present statistically significant difference for the ∆E for all the studied cements, neither for ∆L, ∆a and ∆b. For the bond strength, all the studied cements showed statistically significant differences to each other, with the highest result for the RelyX Veneer® (29.07 MPa) cement, followed by the cement with CQ (21.74 MPa) and CQ+PPD (19.09 MPa) cement; the lowest result was obtained by the cement using only PPD as a photoinitiator (13.99 MPa). So, based on the studied parameters, PPD was not advantageous as photoinitiator of resin cements, because it showed a low value of bond strength to the ceramics and no superior color stability.

Effect of light curing units on color stability and mechanical properties of resin cements after aging

“…These free radicals are generated by highly reactive chemical specimens that have an affinity for electrons localized in the double carbon chains of BIS-GMA, TEGDMA, and UDMA (all derived from the vinyl methacrylate monomer) [6]. Light-cured resin cements are highly suitable for the cementation of thin esthetic restorations (laminates and thin inlays) (up to 2 mm) [3,7]. This is because the thickness and intrinsic color of the restoration may interfere with the light transmission capacity and thereby, affect the adequate polymerization of the material.…”

Avaliação in vitro e in vivo de um sistema restaurador resinoso isento de Bisfenol-A, adaptado para uso na fixação de bráquetes ortodônticos

“…Por outro lado, não devem apresentar força de adesão muito superior a esses valores, pois isso pode ocasionar fraturas do esmalte durante a remoção dos bráquetes (Reynolds, 1975;Yamamoto et al, 2006;Prietsch et al, 2007;Holberg et al, 2014;Dumbryte et al, 2018). Paralelamente, na área da Odontologia, vários autores relataram que o condicionamento ácido associado à utilização de adesivos e compósitos, promove uma maior resistência ao cisalhamento (Årtun e Bergland, 1984;Knox et al, 2001;Han et al, 2007;Hikita et al, 2007;Luhrs et al, 2010;Demirtas et al, 2015;Jurišić et al, 2015) e ao microcisalhamento (Shimada et al, 2002;Nagayassu et al, 2011;Bavbek et al, 2013;Rosa et al, 2015;Kavitha et al, 2016;Righi et al, 2018).…”