Kinetic parameters and monomeric conversion of different dental composites using standard and soft-start photoactivation modes

Abstract

This paper evaluates the photopolymerization kinetics and degree of conversion of different com mercial dental composites when photoactivated by a LED curing unit using two different modes (standard and soft start mode). The investigation was performed on with RelyX ARC (dual cured), Filtek Z 350 (Nanocomposite), Filtek Z 250 (Hybrid), and Filtek Z 350flow (Flowable) resin composites. The analysis used was attenuated total reflection with a Fourier transform infrared (ATR FTIR). The RelyX ARC resin demonstrated the highest degree of conversion with both LED photoactivation modes. For this resin a 28% decrease in maximum rate was observed and the time to reach its highest rate was almost 2.3 times higher than when the soft start photoactivation light curing was used. Z 350flow resin recorder a higher maximum rate using the soft start mode rather than the standard mode. In contrast, the Z 250 showed a higher value using the standard mode. Although Z 250 and Z 350 showed a higher total degree of conversion effectiveness using the soft start mode, RelyX and Z 350flow achieved a higher value using the standard mode.

Kinetic Parameters during Bis-GMA and TEGDMA Monomer Polymerization by ATR-FTIR: The Influence of Photoinitiator and Light Curing Source

“…The percent nonconverted double carbon bonds (%C=C) were determined using the absorbance peak intensities for the C=C bonds at 1637 cm −1 (peak corresponding to the aliphatic chains) and C=C bonds at 1610 cm −1 (peak corresponding to the aromatic chains) before and after the polymerization (referring to (1)) [5,6,27,28]. The corresponding DC was calculated by subtracting this rate from 100%:…”

“…Based on max results, resin photoactivation protocols that recommend a reduced initial exposure time may affect the DC of the resin and, consequently, its properties. Denis et al [27] decreased max by modulating the photoactivation source: that is, the light intensity of the photoactivation equipment starts being lower and increases over time. This decreased light intensity is believed to better accommodate the molecules initially, which decreases the contraction stress in the resin because of the slower conversion [46].…”

“…Real-time Fourier transform infrared (RT-FTIR) spectroscopy is a nondestructive technique widely used in recent years to follow reaction kinetics of such photoactivated composite resins [24]. This technique has been used in studies to evaluate the monomer DC and composite resin polymerization kinetics [25][26][27][28][29].…”

Avaliação do grau de conversão monomérica, parâmetros de cinética de polimerização e determinação de monômeros residuais em resinas experimentais

“…Esta técnica vem sendo aplicada em estudos da avaliação do grau de conversão monomérica e no estudo da cinética de polimerização de resinas compostas (BRAGA; FERRACANE, 2002;TRUJILLO et al, 2004;DARONCH et al, 2006;D'ALPINO et al, 2007;BRANDT et al, 2011;DENIS et al, 2012b), sendo considerada adequada para esses propósitos.…”