Degree of conversion of adhesive systems light-cured by LED and halogen light

Abstract

This study evaluated the effect of blue light emitting diode (LED) and quartz tungsten halogen (QTH) on the degree of conversion (DC) of an etch-and-rinse Single Bond adhesive system (SB) and a mixture composed of primer solution and resin bond from Clearfil SE Bond self-etching adhesive system (CB) using Fourier transform infrared analysis (FTIR). Adhesives were applied to potassium bromide pellet surfaces and FTIR analyses were performed before and after photo-activation for 10 s with either LED (Freelight 1 -400 mw/ cm 2 ) or QTH (XL 3000 -630 mw/cm 2 ) light-curing units (n=8). Additional FTIR spectra were obtained from photo-activated samples stored in distilled water for 1 week. The DC was calculated by comparing the spectra obtained from adhesive resins before and after photo-activation. The results were analyzed by two-way split-plot ANOVA and Tukey's test (p<0.05). Both adhesive systems exhibited low DC (%) immediately after photo-activation (SB/QTH: 18.7 ± 3.9; SB/LED: 13.5 ± 3.3; CF/QTH: 13.6 ± 1.9; CF/LED: 6.1 ± 1.0). The DC of samples light-cured with LED was lower than DC of those light-cured with QTH, immediately after light curing and after 1 week (SB/QTH: 51.3 ± 6.6; SB/LED: 50.3 ± 4.8; CF/QTH: 56.5 ± 2.9; CF/LED: 49.2 ± 4.9). The LED curing unit used to photo-activate the adhesive resins promoted lower DC than the QTH curing unit both immediately after light curing and 1 week after storage in water.

Mechanical properties and degree of conversion of etch-and-rinse and self-etch adhesive systems cured by a quartz tungsten halogen lamp and a light-emitting diode

“…However, adhesives usually present different comonomers and organic solvents compared to dental composites, and the latter can affect the polymerization. Despite these differences, the effect of LCUs on the adhesive system DC has been scarcely studied (Arrais et al, 2007;Faria-e-Silva et al, 2010a;Ye et al, 2007a).…”

Degree of Conversion of Etch-and-Rinse and Self-etch Adhesives Light-cured Using QTH or LED

“…It is uncertain, though, whether the DC could increase over longer periods, as the literature presents contrasting findings regarding the increase in conversion over the course of time. 17,28 The polymerization process of adhesive resins is dependent on many factors, such as monomer structure and functionality, 1 viscosity, 1,24 temperature 24 and the presence of solvents. 10,[22][23]27 Thus, the current study did not aim to compare the DC among the bonding agents, but rather the effect of the LCUs for each system.…”

“…Despite these differences, the effect of LCUs on the DC of adhesive systems has seldom been evaluated. 7,17 The current study evaluated the effect of one QTH and three LED LCUs on the DC of four commercial adhesives systems. The null-hypothesis tested was that the type of LCU would not impact the DC of the different systems.…”

Effects of curing units and staining solutions on the color susceptibility of a microhybrid composite resin

“…17 Essentially, it can be sorted into 3 broad categories (in descending order of importance): the properties of the restorative material used, the clinical conditions, and the bioenvironment in which the restoration is placed. The first can be further analyzed on the basis of the composition of the composite material, 3,18 its degree of polymerization, 19,20 its physical stability (resistance to volumetric shrinkage and surface characteristics), chemical stability (resistance to photo-oxidation and sorption), 21 and its biological stability (resistance to both absorption and adsorption of staining substances). 22 Variable clinical parameters include the source of the curing light, 23,24 curing mode, 25 curing time, 1 the distance between the light source and resin surface, 26 and the surface characteristics of the resin.…”