Influence of curing modes on thermal stability, hardness development and network integrity of dual-cure resin cements (original) (raw)
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Operative Dentistry, 2012
SUMMARY Objectives This study evaluated the degree of conversion (DC) and working time (WT) of two commercial, dual-cured resin cements polymerized at varying temperatures and under different curing-light accessible conditions, using Fourier transformed infrared analysis (FTIR). Materials and Methods Calibra (Cal; Dentsply Caulk) and Variolink II (Ivoclar Vivadent) were tested at 25°C or preheated to 37°C or 50°C and applied to a similar-temperature surface of a horizontal attenuated-total-reflectance unit (ATR) attached to an infrared spectrometer. The products were polymerized using one of four conditions: direct light exposure only (600 mW/cm2) through a glass slide or through a 1.5- or 3.0-mm-thick ceramic disc (A2 shade, IPS e.max, Ivoclar Vivadent) or allowed to self-cure in the absence of light curing. FTIR spectra were recorded for 20 min (1 spectrum/s, 16 scans/spectrum, resolution 4 cm−1) immediately after application to the ATR. DC was calculated using standard techniques...
Influence of composite inlay/onlay thickness on hardening of dual-cured resin cements
Journal (Canadian Dental Association), 2000
This investigation evaluated the effect of resin composite inlay/onlay thickness on the hardness of a group of eight dual-cure resin-based cements. Fourteen disc specimens measuring 6 mm in diameter and 2.5 mm thick were prepared from each of eight dual-cure cements: Adherence, Choice, Duolink, Enforce, Lute-It, Nexus, Resinomer and Variolink. Two specimens from each material were directly light-cured while the remainder of the specimens were light-cured through resin composite spacers varying in thickness from 1 mm to 6 mm. Curing through the spacers always resulted in a decrease in the Knoop hardness number. For some cements, hardness values were reduced by 50% or more when the resin composite spacer thickness was 4 mm or greater even when measurements were made one week after dual-curing. Low hardness values indicate the presence of a weak chemical-curing mechanism that may compromise cement quality in areas of the cavity not readily accessible to the curing light.
Effect of Activation Mode on Flexural Strength and Elasticity Modulus of Dual Cure Resin Cements
Odovtos - International Journal of Dental Sciences, 2016
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=2...
Influence of viscosity and curing mode on degree of conversion of dual-cured resin cements
European journal of dentistry, 2013
The purpose of this study was to evaluate the effects of the viscosities and curing modes on the degree of conversion (DC) of two resin cements. Eight experimental groups were evaluated (n=5), according to the dual-cured resin cements (Nexus 2/Variolink II), viscosity (low and high) and evaluation time (5 minutes and 24 hours). The resin cements were applied to surface of a horizontal attenuated-total-reflectance unit and were polymerized either with self-cure (SC) or light exposure (XL3000/3M ESPE) for 40 seconds. Infrared spectra were obtained after 5 minutes and 24 hours (Nicolet 520 FT-IR/Thermo Scientific Inc.). DC was calculated according to changes in aliphatic-to-aromatic peak ratios pre- and post-curing. Data (%) were analyzed by 3-way repeated measure ANOVA (curing mode, viscosity and time interval) and Tukey's post-hoc test (P<.05). The dual-polymerizing mode provided higher DC than auto-polymerization. The DC mean values increased for both resin cements after 24 h...