Pre-heated dual-cured resin cements: analysis of the degree of conversion and ultimate tensile strength

Abstract

This study evaluated the degree of conversion (DC) and ultimate tensile strength (UTS) of dual-cured resin cements heated to 50º C prior to and during polymerization. Disc-and hourglass-shaped specimens of Rely X ARC (RX) and Variolink II (VII) were obtained using addition silicon molds. The products were manipulated at 25º C or 50º C and were subjected to 3 curing conditions: light-activation through a glass slide or through a pre-cured 2-mm thick resin composite disc, or they were allowed to self-cure (SC). All specimens were dark-stored dry for 15 days. For DC analysis, the resin cements were placed into the mold located on the center of a horizontal diamond on the attenuated total reflectance element in the optical bench of a Fourier Transformed Infrared spectrometer. Infrared spectra (n = 6) were collected between 1680 and 1500 cm -1 , and DC was calculated by standard methods using changes in ratios of aliphatic-to-aromatic C=C absorption peaks from uncured and cured states. For UTS test, specimens (n = 10) were tested in tension in a universal testing machine (crosshead speed of 1 mm/min) until failure. DC and UTS data were submitted to 2-way ANOVA, followed by Tukey's test (α= 5%). Both products showed higher DC at 50º C than at 25º C in all curing conditions. No significant difference in UTS was noted between most light-activated groups at 25º C and those at 50º C. VII SC groups showed higher UTS at 50º C than at 25º C (p < 0.05). Increased temperature led to higher DC, but its effects on resin cement UTS depended on the curing condition.

Effect of pre-heated dual-cured resin cements on the bond strength of indirect restorations to dentin

“…Therefore, the research hypothesis was accepted for this product regardless of the activation mode. This finding is in agreement with those of studies that evaluated preheated LAs, 22,23 and demonstrates that the previously shown 24 increased LA monomer conversion and improved mechanical properties do increase bond strength to dentin. Possibly, decreased resin viscosity and high radical mobility were not the only factors contributing to the greater bond strength.…”

Influence of the interposition of ceramic spacers on the degree of conversion and the hardness of resin cements

“…However, the thickness of indirect materials interposed during photo-activation is a key factor for light attenuation, and polymerization generally decreases as thickness increases. 12 Some studies employing FTIR or FT-Raman used thick (from 0.5 to 1.0 mm) specimens, 14,19 approximately 10 to 20 times thicker than those used in the adhesive luting of indirect restorations. Furthermore, there is a difference in the behavior of thin films as opposed to bulk specimens.…”

Effect of Cements at Different Temperatures on the Clinical Performance and Marginal Adaptation of Inlay‐Onlay Restorations In Vivo

“…The resin cements were applied at 25°C or were heated to 37°C or 54°C prior to use with the preheating method used in previous studies . For experimental groups, base and catalyst pastes were equally dispensed on a glass plate laying on a heating stirrer surface (C‐MAG HS 7; IKAMAG, Staufen, Germany) previously set to 37°C and 54°C.…”