Induction of DNA double-strand breaks in human gingival fibroblasts by eluates from titanium dioxide modified glass ionomer cements

Objectives. (1) To investigate the genotoxicity of a glass ionomer cement (GIC) and GIC incorporated with titanium dioxide nanopoarticle (TiO(2)NPs) and with microparticle (TiO(2)MPs) on DNA double-strand breaks of human gingival fibroblast cells (HGFs). (2) To compare the genotoxic differences between GIC and two modified cements. Methods. TiO(2)NPsGIC and TiO(2)MPsGIC were prepared by adding 10% w/w of TiO(2)NPs and TiO(2)MPs to the GIC powder and hand-mixed followed the manufacturer instruction. Dul-becco's Minimum Essential Medium (DMEM) was used as a culture medium for HGFs and eluate preparation. Eluates from all groups were collected for XTT cell viability assay to obtain EC50 values. gamma-H(2)AX immunofluorescence assay was performed to detect DNA double-strand breaks (DSBs) of HGFs. Results. EC50 values were from 38% to 60% and eluate concentrations at 20% and 5% were selected for gamma-H(2)AX immunofluorescence assay. At both concentrations, HGFs exposed to eluates from all cements groups had fewer mean foci per cell and higher percentage of free foci cells than H2O2 (p <0.05). At 20% concentration, cells exposed to eluates from both TiO(2)NPsGIC and TiO(2)MPsGIC groups had fewer mean foci per cell and higher percentage of free foci cell than GIC and culture medium (p <0.05). Significance. Neither GIC nor 10% TiO2-modified GICs had a genotoxic effect on HGFs. Both TiO(2)NPsGIC and TiO(2)MPsGIC demonstrated less genotoxic effect than GIC. When comparing between the two modified cements, there was no genotoxic difference between the modified cements from different particle sizes (nanoparticle and micro-particle) of TiO2. (C) 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.