Pre-heated dual-cured resin cements: analysis of the degree of conversion and ultimate tensile strength
Braz. oral res
; 25(2): 174-179, Mar.-Apr. 2011. tab
Article
in En
| LILACS
| ID: lil-583853
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BR1.1
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 percent). 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.
Key words
Full text:
1
Index:
LILACS
Main subject:
Tensile Strength
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Resin Cements
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Self-Curing of Dental Resins
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Polymerization
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Hot Temperature
Limits:
Humans
Language:
En
Journal:
Braz. oral res
Journal subject:
ODONTOLOGIA
Year:
2011
Type:
Article
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Project document