Physical, chemical and antimicrobial evaluation of a composite material containing quaternary ammonium salt for braces cementation Mari Miura Sugii a , Fábio Augusto de Souza Ferreira b, ⁎, Karina Cogo Müller c , Debora Alves Nunes Leite Lima a , Francisco Carlos Groppo c , Hidetake Imasato b , Ubirajara Pereira Rodrigues-Filho b , Flávio Henrique Baggio Aguiar a a Departamento de Odontologia Restaurativa, Faculdade de Odontologia de Piracicaba – Universidade de Campinas, Piracicaba, SP 13414-903, Brazil b Grupo de Química de Materiais Híbridos e Inorgânicos, Instituto de Química de São Carlos – Universidade de São Paulo, São Carlos, SP 13563-120, Brazil c Departamento de Ciências Fisiológicas, Área de Farmacologia, Anestesiologia e Terapeutica, Faculdade de Odontologia de Piracicaba – Universidade de Campinas, Piracicaba, SP 13414-903, Brazil abstract article info Article history: Received 8 July 2016 Received in revised form 11 November 2016 Accepted 17 December 2016 Available online 20 December 2016 The antibiofilm effect of iodide quaternary ammonium methacryloxy silicate (IQAMS) in Transbond XT Light Cure Adhesive resin used for braces cementation was evaluated. Fourier Transform Infrared (FTIR) spectroscopy confirmed IQAMS formation and Scanning Electron Microscopy coupled to Energy-Dispersive X-ray Spectrosco- py (SEM-EDS) revealed that as coating, the quaternary ammonium groups from IQAMS were homogeneously dispersed throughout the surface. When incorporated, the composite material presented homogeneous disper- sion throughout the resin. Assays with Streptococcus mutans demonstrated enhanced antibiofilm effect for the IQAMS coated resin, with much lower colony-forming units (CFU), in comparison to incorporated IQAMS. Such a difference was assigned to low availability of quaternary ammonium groups at the surface of resin when IQAMS was incorporated, hindering its antibiofilm effect. Additionally, the incorporation of IQAMS led to slight decrease in ultimate bond strength (UBS) and shear bond strength (SBS), in comparison to the neat commercial resin. Thus, the synthesized IQAMS displays great potential as antibiofilm coating or sealant to prevent oral infections in brackets during orthodontic treatment. © 2016 Elsevier B.V. All rights reserved. Keywords: Antibiofilm Quaternary ammonium Methacrylate Streptococcus mutans Orthodontic 1. Introduction The goal of orthodontic treatment is to provide complete and inte- grated therapy for patients' oral health; restoring function as well as aesthetics [1–3]. Many orthodontic treatments available involve cemen- tation of brackets and other metallic devices combined with elastic lig- atures and arc wires, hindering hygiene. This results, for instance, in large Streptococcus mutans [4,5] and Candida albicans [6] biofilm accu- mulation and colonization, which it can lead to dental caries, compromising the oral health of patients [1,7–9]. The prevention of dental caries requires commitment and effort of the patient to properly cleanse the orthodontic devices, in addition to make use of a less cario- genic diet [10]. In order to support the patients and become the ortho- dontic treatment more effective, researchers have developed new materials with antimicrobial (bactericidal/bacteriostatic) properties [11,12]. Organically modified silicates (ORMOSIL) are hybrid materials [13] that contain organic functionalities covalently bonded to the silicate network providing especial properties [14,15]. Sol-gel process is a suit- able approach to obtain ORMOSIL-based materials under mild conditions with multifunctional properties [13,14,16–18]. In a typical sol-gel process, silicon alkoxides precursors undergo acid or basic-cata- lyzed hydrolysis forming silanol groups (Si–OH) that further react to form siloxane bonds (Si–O–Si) and hence lead to the development of a tridimensional network [13,17,18]. Given its low toxicity and biocom- patibility, ORMOSIL have been used as biomaterial via immobilization of biomolecules or modification of the silicate network with functional groups with biological activity [16,18,19]. Quaternary ammonium salts are among the groups most used to aggregate antimicrobial properties to the silicate network, since they are already widely used as disinfectant in food production and medical appliances to prevent bac- terial contaminations [20]. In this regard, dimethyloctadecyl[3- (trimethoxysilyl)propyl] ammonium chloride, an ORMOSIL precursor, has emerged as an effective compound for development of antibacterial dental composites [19,21–24]. The antimicrobial activity of quaternary ammonium groups is attributed to their ionic part combined to a lipophilic chain [25]. Palermo et al. found that the alkyl chain can penetrate into the cell causing lysis and death [26]. Li et al. [27] showed a large decrease in colony-forming unity (CFU) on samples containing quaternary ammonium groups with 12 carbons length. Additionally, Gong et al. [28] observed that the modi fication of the ORMOSIL network with methacrylate groups led to development of quaternary Materials Science and Engineering C 73 (2017) 340–346 ⁎ Corresponding author. E-mail address: ferreira.fabio.a.s@gmail.com (F.A.S. Ferreira). http://dx.doi.org/10.1016/j.msec.2016.12.084 0928-4931/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec