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 (TiONPs) and with microparticle (TiOMPs) on DNA double-strand breaks of human gingival fibroblast cells (HGFs). (2) To compare the genotoxic differences between GIC and two modified cements.

METHODS

TiONPsGIC and TiOMPsGIC were prepared by adding 10% w/w of TiONPs and TiOMPs to the GIC powder and hand-mixed followed the manufacturer instruction. Dulbecco'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 EC values. γ-H2AX immunofluorescence assay was performed to detect DNA double-strand breaks (DSBs) of HGFs.

RESULTS

EC values were from 38% to 60% and eluate concentrations at 20% and 5% were selected for γ-H2AX 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 HO (p<0.05). At 20% concentration, cells exposed to eluates from both TiONPsGIC and TiOMPsGIC 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% TiO-modified GICs had a genotoxic effect on HGFs. Both TiONPsGIC and TiOMPsGIC 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 TiO.