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(Reference retrieved automatically from Google Scholar through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Effect of Temperature on the Degree of Conversion and Working Time of Dual-Cured Resin Cements Exposed to Different Curing Conditions

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Author(s):
Oliveira, M. [1] ; Cesar, P. F. [2] ; Giannini, M. [3] ; Rueggeberg, F. A. [4] ; Rodrigues, J. [5] ; Arrais, C. A. [1]
Total Authors: 6
Affiliation:
[1] Univ Guarulhos, Dept Operat Dent, Guarulhos - Brazil
[2] Univ Sao Paulo, Dept Dent Mat, Sao Paulo - Brazil
[3] Univ Estadual Campinas, Dept Restorat Dent, Piracicaba - Brazil
[4] Georgia Hlth Sci Univ, Sch Dent, Augusta, GA - USA
[5] Univ Guarulhos, Dept Restorat Dent, Guarulhos - Brazil
Total Affiliations: 5
Document type: Journal article
Source: Operative Dentistry; v. 37, n. 4, p. 370-379, 2012.
Web of Science Citations: 26
Abstract

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 degrees C or preheated to 37 degrees C or 50 degrees 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/cm(2)) 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 of observing changes in aliphatic-to-aromatic peak ratios precuring and 20-min postcuring as well as during each 1-second interval. Time-based monomer conversion analysis was used to determine WT at each temperature. DC and WT data (n=6) were analyzed by two-way analysis of variance and Tukey post hoc test (p=0.05). Results: Higher temperatures increased DC regardless of curing mode and product. For Calibra, only the 3-mm-thick ceramic group showed lower DC than the other groups at 25 degrees C (p=0.01830), while no significant difference was observed among groups at 37 degrees C and 50 degrees C. For Variolink, the 3-mm-thick ceramic group showed lower DC than the 1-mm-thick group only at 25 degrees C, while the self-cure group showed lower DC than the others at all temperatures (p=0.00001). WT decreased with increasing temperature: at 37 degrees C near 70% reduction and at 50 degrees C near 90% for both products, with WT reduction reaching clinically inappropriate times in some cases (p=0.00001). Conclusion: Elevated temperature during polymerization of dual-cured cements increased DC. WT was reduced with elevated temperature, but the extent of reduction might not be clinically acceptable. (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