Ex vivo assessment of genotoxicity and cytotoxicity in murine fibroblasts exposed to white MTA or white Portland cement with 15% bismuth oxide E. G. Zeferino 1 , C. E. S. Bueno 1 , L. M. Oyama 2 & D. A. Ribeiro 2 1 Endodontic Area, Center for Dental Research, Sa ˜o Leopoldo Mandic University, Campinas, Brazil; and 2 Departamento de Biocie ˆncias, Universidade Federal de Sao Paulo, Sao Paulo, Brazil Abstract Zeferino EG, Bueno CES, Oyama LM, Ribeiro DA. Ex vivo assessment of genotoxicity and cytotoxicity in murine fibroblasts exposed to white MTA or white Portland cement with 15% bismuth oxide. International Endodontic Journal, 43, 843–848, 2010. Aims To evaluate whether white mineral trioxide aggregate (MTA) or white Portland cement with 15% bismuth oxide were able to induce genetic damage and cellular death ex vivo. Methodology Aliquots of 1 · 10 4 murine fibro- blasts were incubated at 37 °C for 3 h with MTA (white) or white Portland cement with 15% bismuth oxide, at final concentrations ranging from 10 to 1000 lg mL )1 individually. Data of three independent repeats from the comet assay and the trypan blue exclusion test were assessed by the one-way anova followed by Tukey’s test. Results Mineral trioxide aggregate or Portland cement containing bismuth oxide did not produce genotoxic effects with respect to the single-cell gel (comet) assay data for all concentrations evaluated. Furthermore, no cytotoxicity was observed for MTA or Portland cement. Conclusion White MTA or white Portland cement containing 15% bismuth oxide were not genotoxic and cytotoxic. Keywords: cytotoxicity, genotoxicity, mineral tri- oxide aggregate, Portland cement. Received 11 January 2010; accepted 14 April 2010 Introduction Several endodontic materials are used as apical root-end fillings including zinc oxide eugenol cements, glass–ionomer cements, composite resins and mineral trioxide aggregate (MTA). MTA has been shown to have potential as a root-end filling material (Pace et al. 2008), root canal filling material, repair material for root perforation and pulpotomy medicament because of its excellent sealing ability in the presence of moisture (Maroto et al. 2007). Both tooth-coloured and grey are available (Pe ´rez et al. 2003). Studies have identified similarities between MTA and Portland cements (Torabinejad et al. 1995). Indeed Portland cements contain the same chemical elements as MTA (Wucherpfennig & Green 1999). This suggests that Portland cement has the potential to be used as a less expensive root-end filling material (Menezes et al. 2004). However, white Portland cements do not have sufficient radiopacity, despite their excellent physicochemical properties (Bueno et al. 2009). Parti- cles of several chemical compounds could be incorpo- rated into Portland cement, such as calcium tungstate, lead oxide or bismuth oxide to provide radiopacity. In an earlier study, white Portland cement with 15% bismuth oxide had the radiopacity required for an endodontic cement (Bueno et al. 2009). Nevertheless, several studies report that the presence of radiopacifiers can influence negatively the original properties of the compound as well as promote noxious activities on Correspondence: Daniel A. Ribeiro, DDS, PhD, Departamento de Biocie ˆncias, Universidade Federal de Sa ˜o Paulo – UNIFESP, Av. Ana Costa, 95, Vila Mathias, Santos – SP 11060-001, Brazil (e-mails: daribeiro@unifesp.br; daribeiro@pesquisador. cnpq.br). doi:10.1111/j.1365-2591.2010.01747.x ª 2010 International Endodontic Journal International Endodontic Journal, 43, 843–848, 2010 843