Research Article Differences of Cytotoxicity of Orthodontic Bands Assessed by Survival Tests in Saccharomyces cerevisiae Tatiana Siqueira Gonçalves, 1 Luciane Macedo de Menezes, 1 Luciele Gonzaga Ribeiro, 2 Catieli Gobetti Lindholz, 2 and Renata Medina-Silva 2 1 Department of Orthodontics, Dentistry Faculty, Pontif´ ıcia Universidade Cat´ olica do Rio Grande do Sul, Avenida Ipiranga 6681, Building 6, Room 209, 90619-900 Porto Alegre, RS, Brazil 2 Immunology and Microbiology Laboratory, Biosciences Faculty, Pontif´ ıcia Universidade Cat´ olica do Rio Grande do Sul, Avenida Ipiranga 6681, Building 12, Lab 12D, 90619-900 Porto Alegre, RS, Brazil Correspondence should be addressed to Tatiana Siqueira Gonc ¸alves; tatianasiqueiragoncalves@gmail.com Received 19 October 2013; Revised 6 December 2013; Accepted 7 December 2013; Published 6 January 2014 Academic Editor: Susana Viegas Copyright © 2014 Tatiana Siqueira Gonc ¸alves et al. his 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. he aim of this study was to evaluate the cytotoxicity induced by orthodontic bands through survival tests on Saccharomyces cerevisiae, a microorganism that presents several genetic and biochemical characteristics similar to human cells. hree groups of bands were evaluated: silver soldered (SSB), laser soldered (LSB), and bands without any solder (WSB). Yeast cells were directly exposed to the bands and indirectly, when a previous elution of the metals in artiicial saliva was performed. he negative control was composed of yeast cells or artiicial saliva not exposed to any kind of metal. In the direct exposure experiments, all tested groups of bands induced a slight reduction in yeast viability compared to the control. his efect was more intense for the SSB, although not statistically signiicant. For the indirect exposure experiments, the SSB induced a statistically signiicant decrease in cell viability compared to the LSB. here were no signiicant diferences between the survival rates of the negative control and the LSB group in both direct and saliva tests. SSBs were cytotoxic, whilst LSBs were not, conirming that laser soldering may be a more biocompatible alternative for use in connecting wires to orthodontic appliances. 1. Introduction Biocompatibility refers to the ability of a biomaterial to per- form its desired function with respect to a medical therapy, without eliciting any undesirable local or systemic efects in the recipient or beneiciary of that therapy but generating the most appropriate beneicial cellular or tissue response in that speciic situation and optimizing the clinically relevant per- formance of that therapy [1]. Corrosion is the main concern when biocompatibility of orthodontic metallic materials is evaluated. he release of several metallic ions [2] may lead to hypersensitivity and allergic reactions, either locally as well as systemically [3]. In daily practice, it is usual to use orthodontic bands during interceptive and corrective treatments. he bands are generally made of stainless steel and are composed of nickel, iron and chromium, and it is considered a biocompatible alloy [4, 5]. However, in several clinical situations, it is nec- essary to connect orthodontic wires to the bands, especially when auxiliary appliances, such as lingual arches and maxillary expanders, are made. To connect the support wires to the appliances, silver solder is the alloy of choice, due to its proven efectiveness, low cost, and ease of use. However, the silver solder alloy contains silver, copper, and zinc. hese ions present a major tendency to be released to the buccal cavity [6] and they may have cytotoxic efects, resulting in decrease of cell viability [5]. Cadmium used to be added to the com- position of silver solder alloys some decades ago [7] and, due to the process of zinc obtaining from the ores, cadmium may appear as a zinc contaminant [8]. It is important to remember that cadmium exposure is responsible for hepatic, renal, and myocardial damage characterized by increased creatinine, total and direct bilirubin concentrations and increased ALT and lactate dehydrogenase (LDH) activities [9]. Besides this, Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 143283, 7 pages http://dx.doi.org/10.1155/2014/143283