Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 838460, 6 pages http://dx.doi.org/10.1155/2013/838460 Research Article Biaxial Flexural Strength of High-Viscosity Glass-Ionomer Cements Heat-Cured with an LED Lamp during Setting Gustavo Fabián Molina, 1 Ricardo Juan Cabral, 1 Ignacio Mazzola, 1 Laura Brain Lascano, 1 and Jo E. Frencken 2 1 Department of Dental Materials, Dental Faculty, National University of C´ ordoba, Maya de la Torre s/n, 5000 C´ ordoba, Argentina 2 Department of Global Oral Health, College of Dental Sciences, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, Te Netherlands Correspondence should be addressed to Jo E. Frencken; j.frencken@dent.umcn.nl Received 25 April 2013; Accepted 26 May 2013 Academic Editor: Xiupeng Wang Copyright © 2013 Gustavo Fabi´ an Molina et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Adding heat to glass ionomers during setting might improve mechanical properties. Te aim was to compare the biaxial fexural strength (BFS) between and within four glass ionomers, by time of exposure to a high-intensity LED light-curing unit. Materials and methods. Samples of Fuji 9 Gold Label, Ketac Molar Easymix, ChemFil Rock, and the EQUIA system were divided into three treatment groups ( = 30): without heating (Group 1), heated with LED lamp of 1400mW/cm 2 for 30 s while setting (Group 2), and heated with LED lamp of 1400 mW/cm 2 for 60s while setting (Group 3). Samples were stored for 48 hours in distilled water at 37 ∘ C until tested. BFS was tested, using a universal testing machine at a crosshead speed of 1mm/min. Data were analyzed, using ANOVA test with the Bonferroni correction ( = 0.05). Heating the glass-ionomer cements with an LED curing light of 1400 mW/cm 2 during setting for 30 s increased the BFS value of all GICs. No statistically signifcant diference in mean BFS scores was found between the EQUIA system and ChemFil Rock at 30 s and 60 s. Te mean BFS value was statistically signifcantly higher for the EQUIA system and ChemFil Rock than for Fuji 9 Gold Label and Ketac Molar Easymix at all exposure times. 1. Introduction In general, the longevity of glass-ionomer cement restora- tions, produced using rotary instruments, are considered inferior to resin-based composite and dental amalgam restorations. However, the longevity of high-viscosity glass- ionomer cements used with the atraumatic restorative treat- ment (ART) protocol in permanent teeth was equal to, or greater than, that of equivalent amalgam restorations for up to 6.3 years. Tere was also no diference in longevity between the two types of restorations in primary teeth, assessed according to the same assessment criteria [1, 2]. A similar fnding has been reported regarding the longevity of ART glass-ionomer restorations and resin-composite restorations in primary teeth assessed according to the same assessment criteria [3]. However, the number of trials, upon which the latter conclusion is based, was small. Glass-ionomer cements have certain features that are superior to those of resin-based materials and dental amal- gam [4]. Tese include the following: chemical adhesion to mineralized dental tissues; biological sealing of the cavity interface (including inhibition of bacterial compounds and ability to remineralize dental tissues) [5]; and easy use in a variety of clinical settings [4]. Te major weakness of glass-ionomer cements is their low fracture toughness. Tis feature is likely to improve as the material maturates [6, 7]. Incomplete chemical reactions and sensitivity to water during the frst stage of the setting reaction of glass-ionomer cements lead to sofening and cracking of the cement surface and subsequently to reduction of its wear resistance and fracture toughness [8]. It was thought that one way in which a solution to these adverse conditions could be achieved was to shorten the vulnerable initial stage in the setting reaction. Tis