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

The effect of photopolymerization on the degree of conversion, polymerization kinetic, biaxial flexure strength, and modulus of self-adhesive resin cements

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Author(s):
Aguiar, Thaiane R. [1] ; de Oliveira, Michele [2] ; Arrais, Cesar A. G. [3] ; Ambrosano, Glaucia M. B. [4] ; Rueggeberg, Frederick [5] ; Giannini, Marcelo [1]
Total Authors: 6
Affiliation:
[1] Univ Estadual Campinas, Piracicaba Dent Sch, Dept Restorat Dent, BR-13414903 Piracicaba, SP - Brazil
[2] Univ Guarulhos, Dept Operat Dent, Guarulhos - Brazil
[3] Univ Estadual Ponta Grossa, Dept Operat Dent, Ponta Grossa - Brazil
[4] Univ Estadual Campinas, Piracicaba Dent Sch, Dept Social Dent, BR-13414903 Piracicaba, SP - Brazil
[5] Georgia Regents Univ, Coll Dent Med, Dept Oral Rehabil, Augusta, GA - USA
Total Affiliations: 5
Document type: Journal article
Source: JOURNAL OF PROSTHETIC DENTISTRY; v. 113, n. 2, p. 128-134, FEB 2015.
Web of Science Citations: 19
Abstract

Statement of problem. Understanding the effect of the degree of conversion on the mechanical properties of auto- and dual-polymerizing self-adhesive resin cements leads to a better estimation of their performance in different clinical scenarios. Purpose. The purpose of this study was to evaluate the effect of photopolymerization on the degree of conversion (DC) and polymerization kinetic of 4 dual-polymerized resin cements, 20 minutes after mixing, and its effects on the mechanical properties (biaxial flexural strength {[}FS] and modulus {[}FM]) after short-term aging. Material and methods. Conventional (RelyX ARC and Clearfil Esthetic Cement) and self-adhesive resin cements (RelyX Unicem and Clearfil SA Cement) were applied to a Fourier infrared spectrometer to assess the DC (n=5) under the following 3 polymerization conditions: direct light exposure (dual-polymerizing mode), exposure through the prepolymerized disk, or autopolymerizing. The polymerization kinetic was recorded for 20 minutes. Then, disk-shaped specimens (n=11) were prepared to evaluate the effect of polymerization on the FS and FM in both extreme polymerization conditions (dual-polymerizing or autopolymerizing). Data were statistically analyzed by 2-way repeated measure ANOVA (DC) and by 2-way ANOVA (FS and FM), followed by the Tukey-Kramer post hoc test (alpha=.05). Results. Autopolymerizing groups exhibited reduced DC means, whereas intermediate values were observed when resin cements were polymerized through the disk. All groups exhibited higher DC at the end of 20 minutes. The polymerization kinetic revealed a rising curve, and materials, when directly photopolymerized, reached a plateau immediately after light exposure. Regarding the flexural biaxial testing, most of the resin cements were affected by polymerization mode and differences among groups were product dependent. Conclusions. The resin cements achieved immediate higher DC and mechanical properties when photopolymerized. The total absence of photoactivation may still impair their mechanical properties even after short-term aging. (AU)