scholarly journals The Effect of Light Exposure on Water Sorption and Solubility of Self-Adhesive Resin Cements

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Thaiane Rodrigues Aguiar ◽  
Carolina Bosso André ◽  
Gláucia Maria Boni Ambrosano ◽  
Marcelo Giannini
Keyword(s):  
Water Sorption ◽  
Mechanical Stability ◽  
Light Exposure ◽  
Water Immersion ◽  
Constant Mass ◽  
Resin Cements ◽  
Adhesive Resin ◽  
Direct Light ◽  
Immersion Period ◽  
Effect Of Light

Purpose. To investigate the effect of light activation on the water sorption (WS) and solubility (SL) of resin cements after 24 h and 7 days. Methods. Disk-shaped specimens were prepared using five dual-polymerized cements (four self-adhesive [RelyX Unicem, MaxCem, SeT and G-Cem] and one conventional [Panavia F 2.0]) and divided according to the curing mode (direct light exposure or self-cure) and water immersion period (24 h or 7 days). Specimens were dry-stored and weighed daily until a constant mass was recorded (M1). Then, specimens were stored in water for either 24 h or 7 days and immediately weighed (M2). After desiccation, specimens were weighed again until a constant mass was achieved (M3). WS and SL were calculated and statistically analyzed by Kruskal-Wallis, Dunn and Mann-Whitney U tests (α=0.05%). Results. There was a significant increase in WS for all products after one-week immersion in water. The highest water uptake was observed for autopolymerized groups. Extended water immersion significantly affected the SL for most of autopolymerized cements. Significant differences between products were observed in both tests. Conclusions. The curing mode and the water immersion period may affect the mechanical stability of the resin cements, and these differences appear to be product-dependent.

scholarly journals Effect of Simulated Tooth Temperature on the Degree of Conversion of Self-adhesive Resin Cements Exposed to Different Curing Conditions

2014 ◽  
Vol 39 (2) ◽  
pp. 204-212 ◽  
Author(s):  
CAG Arrais ◽  
CL Chagas ◽  
A Munhoz ◽  
M Oliveira ◽  
AF Reis ◽  
...  
Keyword(s):  
Room Temperature ◽  
Light Exposure ◽  
Degree Of Conversion ◽  
Tooth Surface ◽  
Infrared Analysis ◽  
Resin Cements ◽  
Adhesive Resin ◽  
Curing Conditions ◽  
Surface Temperatures ◽  
Direct Light

SUMMARY Objectives This study evaluated the degree of conversion (DC) of two commercial, self-adhesive resin cements (SARCs) using Fourier transform infrared analysis (FTIR) polymerized at simulated prepared tooth surface temperatures and under different curing conditions. Materials and Methods RelyX U100 (U100, 3M ESPE) and Maxcem Elite (MX, Kerr Corporation) were mixed at 25°C and applied to the surface of a horizontal attenuated total reflectance (ATR) unit, which was near room temperature (RT, control) (25°C) or heated to simulate prepared tooth surface temperatures (28°C and 32°C) and then attached to an infrared spectrometer. The products were polymerized using one of three conditions: direct light exposure through a glass slide (DLE), exposure through a 1.5-mm thick ceramic disc overlay (CO) (A2 shade, IPS e.max, Ivoclar Vivadent), or self-curing (SC). FTIR spectra were recorded for 12 minutes (1 spectrum/s, 16 scans/spectrum, resolution 4 cm−1) immediately after application to the ATR. The DC was calculated using standard techniques of observing changes in aliphatic-to-aromatic peak ratios before and 12 minutes after curing, as well as during each 1-second interval. DC data (n=7) were analyzed by two-way analysis of variance and Tukey's post-hoc test (p=0.05). Results Both simulated tooth temperatures significantly increased DC in all groups of MX and in the CO and SC groups of U100 compared with the RT control. For MX, the self-cure groups exposed to tooth temperatures showed DC values similar to those of the CO groups. For U100, the CO groups showed higher DC values than SC groups regardless of temperature. Time-based conversion profiles ranged according to product, temperature, and curing mode. Conclusions Causing SARCs to polymerize at simulated tooth temperatures increases DC of SARCs compared with room-temperature curing values, mainly in the SC mode.

scholarly journals Afraid of the dark: Light acutely suppresses activity in the human amygdala

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252350
Author(s):  
Elise M. McGlashan ◽  
Govinda R. Poudel ◽  
Sharna D. Jamadar ◽  
Andrew J. K. Phillips ◽  
Sean W. Cain
Keyword(s):  
Light Exposure ◽  
Negative Emotion ◽  
Critical Role ◽  
Dark Light ◽  
Direct Light ◽  
Siemens Scanner ◽  
Amygdala Activity ◽  
Plausible Mechanism ◽  
Dim Light ◽  
Effect Of Light

Light improves mood. The amygdala plays a critical role in regulating emotion, including fear-related responses. In rodents the amygdala receives direct light input from the retina, and light may play a role in fear-related learning. A direct effect of light on the amygdala represents a plausible mechanism of action for light’s mood-elevating effects in humans. However, the effect of light on activity in the amygdala in humans is not well understood. We examined the effect of passive dim-to-moderate white light exposure on activation of the amygdala in healthy young adults using the BOLD fMRI response (3T Siemens scanner; n = 23). Participants were exposed to alternating 30s blocks of light (10 lux or 100 lux) and dark (<1 lux), with each light intensity being presented separately. Light, compared with dark, suppressed activity in the amygdala. Moderate light exposure resulted in greater suppression of amygdala activity than dim light. Furthermore, functional connectivity between the amygdala and ventro-medial prefrontal cortex was enhanced during light relative to dark. These effects may contribute to light’s mood-elevating effects, via a reduction in negative, fear-related affect and enhanced processing of negative emotion.

Water sorption and water solubility of self-etching and self-adhesive resin cements

2015 ◽  
Vol 114 (5) ◽  
pp. 674-679 ◽  
Author(s):  
Aikaterini Petropoulou ◽  
Areti D. Vrochari ◽  
Elmar Hellwig ◽  
Susanne Stampf ◽  
Olga Polydorou
Keyword(s):  
Water Sorption ◽  
Water Solubility ◽  
Resin Cements ◽  
Adhesive Resin

scholarly journals Effect of Insufficient Light Exposure on Polymerization Kinetics of Conventional and Self-adhesive Dual-cure Resin Cements

2017 ◽  
Vol 42 (1) ◽  
pp. E1-E9 ◽  
Author(s):  
Y Jang ◽  
JL Ferracane ◽  
CS Pfeifer ◽  
JW Park ◽  
Y Shin ◽  
...  
Keyword(s):  
Mixed Model ◽  
Light Exposure ◽  
Polymerization Kinetics ◽  
Curing Time ◽  
Resin Cements ◽  
Ceramic Block ◽  
Mixed Model Analysis ◽  
Direct Light ◽  
Light Curing ◽  
Ceramic Restorations

SUMMARY Objectives: The purpose of this study was to investigate the influence of insufficient light exposure on the polymerization of conventional and self-adhesive dual-cure resin cements under ceramic restorations. Methods: Two conventional dual-cure resin cements (Rely-X ARC, Duolink) and two self-adhesive resin cements (Rely-X U200, Maxcem Elite) were polymerized under different curing modes (dual-cure or self-cure), curing times (20 and 120 seconds), and thickness of a ceramic overlay (2 and 4 mm). Polymerization kinetics was measured by Fourier transform infrared spectroscopy for the initial 10 minutes and after 24 hours. Data were analyzed using mixed model analysis of variance (ANOVA), one-way ANOVA/Student-Newman-Keuls post hoc test, and paired t-test (α=0.05). Results: When light-curing time was set to 20 seconds, the presence of the ceramic block significantly affected the degree of conversion (DC) of all resin cements. Especially, the DC of the groups with 20 seconds of light-curing time under 4 mm of ceramic thickness was even lower than that of the self-cured groups at 24 hours after polymerization (p&lt;0.05). However, when light-curing time was set to 120 seconds, a similar DC compared with the group with direct light exposure (p&gt;0.05) was achieved in all dual-cure groups except Maxcem Elite, at 24 hours after polymerization. Conclusions: For both conventional and self-adhesive dual-cure resin cements, insufficient light exposure (20 seconds of light-curing time) through thick ceramic restoration (4 mm thick) resulted in a DC even lower than that of self-curing alone.

scholarly journals Effect of the ceramic translucency on the long-term water sorption and solubility of resin cements

2020 ◽  
Vol 19 ◽  
pp. e201704
Author(s):  
Ana Paula Menezes Vaz Queiroz ◽  
Mariana Menezes Vaz Queiroz ◽  
Saryta Argolo ◽  
Richard Mark Foxton ◽  
Paula Mathias ◽  
...  
Keyword(s):  
Water Sorption ◽  
Experimental Period ◽  
Glass Slide ◽  
Resin Cement ◽  
Test Results ◽  
Constant Mass ◽  
Resin Cements ◽  
Tukey Test ◽  
Low Degree

Aim: The aim of this study was to evaluate the influence of the translucency of ceramic on water sorption and solubility of resin cements over time. Methods: Lithium disilicate ceramic slides (15x15x1 mm), A1 in color and with different translucencies (high-medium-low) were manufactured; and a glass slide with similar dimension was used as control. Under every slide, 15 specimens (8x0.5 mm) from each resin cement were prepared: light-cured (RelyX Veneer); conventional dual-cured (RelyX ARC); and self-adhesive dual-cured (Rely-X U200). The specimens were then sub-divided according to the period of evaluation (immediately, after 6 and 12 months of storage) (n=5). To evaluate the loss or gain of mass, the specimens were dried until a constant mass was reached. Subsequently, they were divided according to the respective period of storage at 37°C in distilled water and weighed immediately following removal from water. After each period, specimens underwent a new dehydration. Values from water sorption and solubility were calculated and statistically analyzed (Anova 3-way/Tukey test). Results: The lower translucency resulted in greater water sorption and solubility for all cements, regardless of the experimental period. The self-adhesive dual-cured cement showed higher water sorption under all experimental periods and had worse values after 1 year aging. Differences among solubility could only be detected after aging, and the light-cured material had higher values after 6 and 12 months. Conclusions: It could be concluded that the low degree of translucency can negatively influence the passage of light and interfere on the durability of the resin cement. The conventional dual-cured resinous agent seemed to be less affected by such condition.

scholarly journals Effect of Activation Mode on Flexural Strength and Elasticity Modulus of Dual Cure Resin Cements

2016 ◽  
Vol 18 (1) ◽  
pp. 61
Author(s):  
Isadora Guimaraes DDS, MSc, PhD ◽  
Fabian Murillo DDS, MSc ◽  
Mario De Goes DDS, MSc, PhD
Keyword(s):  
Flexural Strength ◽  
Elasticity Modulus ◽  
Composite Resin ◽  
Testing Machine ◽  
Resin Cements ◽  
Adhesive Resin ◽  
Luting Cements ◽  
Direct Light ◽  
Light Curing ◽  
Flexural Tests

Objective: This study evaluated the effect of the activation mode on flexural strength and elasticity modulus of four dual cure resin-based cements.  Methods: Two self-adhesive resin cements (Clearfil SA Cement (CSA) and  RelyX U100 (U)) and two conventional resin cements (Clearfil Esthetic Cement (CE)and RelyX ARC (ARC)) were used to produce a total of 45 bar specimens (7x2x2 mm) using three different activation modes (n=15): Direct light-cure (D), Indirect light-cure using a 2mm composite resin barrier (I) and Self-cure (S). Three-point flexural tests were performed after 24 hours water storage at 37° C, using a universal testing machine (Instron) at a cross-speed of 0.5 mm/min until fracture. Flexural strength (MPa) and elasticity modulus values were subjected to ANOVA and Tukey’s Test (=0.05). Results: Data revealed that light polymerized groups presented statistically higher flexural strength (CSA/D=113.63 ± 19.65; CSA/I=80.66 ± 23.74; U/D=101.33 ± 9.8; U/I=94.96 ± 36.9; CE/D=219.08 ± 39.94; CE/I=226.42 ± 34.59; ARC/D=150.03 ± 26.15; ARC/I=111.78 ± 14.28) and also  elasticity modulus values (CSA/D = 2.9 ± 0.6; CSA/I = 1.5 ± 0.4; U/D = 2.9 ± 0.5; U/I = 2.6 ± 1.4; CE/D = 6.5 ± 1.3; CE/I = 5.8 ± 1.0; ARC/D = 4.2 ± 0.93; ARC/I = 2.5 ± 0.5) compared to self-cured groups (flexural strength: CSA/S=65.81 ± 21.84; U/S=53.62 ± 28.73; CE/S=129.02 ± 51.67; ARC/S=77.98 ±19.61 and elasticity modulus: CSA/S = 1.4 ± 0.5; U/S = 1.2 ± 0.7; CE/S = 2.2 ± 1.5; ARC/S = 1.0 ± 0.5). The usage of a composite resin barrier only affected the mechanical properties of ARC and CSA. Conventional resin cements presented higher flexural strength values than the self-adhesive cements. CE presented the highest values compared to all other cements. No statistical difference was observed between self-adhesive cements. Conclusion: Light-curing of resin luting cements produced higher flexural strength for all tested materials. Similar mechanical behavior was observed for the tested self-adhesive cements. 

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