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

Author(s)

Franca, Flavio Alvares ^[1] ; de Oliveira, Michele ^[1] ; Rodrigues, Jose Augusto ^[1] ; Galvao Arrais, Cesar Augusto ^[1]

Affiliation

^[1] Univ Guarulhos, Dept Operat Dent, Sch Dent, BR-07023070 Guarulhos, SP - Brazil

• Document type: Journal article
• Source: Brazilian Oral Research; v. 25, n. 2, p. 174-179, MAR-APR 2011.
• Web of Science Citations: 8

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. (AU)

• FAPESP's process: 08/04970-6 - Pre-heating of dual-cured resin cements during the simulation of indirect ceramic restorations: effects on the degree of conversion after different curing modes
• Grantee: César Augusto Galvão Arrais
• Support Opportunities: Regular Research Grants
• FAPESP's process: 08/07557-2 - Pre-heating of dual-cured resin cements during the simulation of indirect ceramic restorations: effects on the degree of conversion after different curing modes
• Grantee: Michele de Oliveira
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 07/06083-4 - Long-term evaluation of the bond strength, nanoleakage patterns and ultramorphological characteristics of resin-dentin interfaces produced by self-adhesive cements
• Grantee: André Figueiredo Reis
• Support Opportunities: Regular Research Grants