title: Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test.
abstract: Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR) spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm). Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length) were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan) was performed at the top and bottom (depth=2 mm) surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.
authors.affiliation: Associate Professor, Department of Dental Biomaterials, Tehran University of Medical Sciences, Iranian Tissue Bank and Research Center, Tehran University of Medical Sciences Tehran, Iran.
authors.forename: Tahereh-Sadat
authors.initials: TS
authors.lastname: Jafarzadeh
authors.affiliation: Associate Professor, Department of Pharmaceutics, School of Pharmacy, Shahid Bahashti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Erfan
authors.affiliation: Assistant Professor, Research Center for Science and Technology in Medicine and Department of Dental Biomaterials, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Marjan
authors.initials: M
authors.lastname: Behroozibakhsh
authors.affiliation: Assistant Professor, Research Center for Science and Technology in Medicine and Department of Dental Biomaterials, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Fatemi
authors.affiliation: Ph.D Candidate, Research Center for Science and Technology in Medicine and Department of Dental Biomaterials, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Masaeli
authors.affiliation: Assistant Professor, Department of Dental Biomaterials, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Yashar
authors.initials: Y
authors.lastname: Rezaei
authors.affiliation: Assistant Professor, Dental Materials Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Bagheri
authors.affiliation: Dental Student, The International Branch of Shahid Behesti University of Medical Sciences and Health Services, Tehran, Iran.
authors.forename: Yasaman
authors.initials: Y
authors.lastname: Erfan
keywords: Composite resins; Fourier transform infrared spectroscopy; hardness; polymerization