Avaliação do efeito de bráquetes, cerâmicos e plásticos, sobre a viabilidade celular e produção de óxido nítrico em células J774

Abstract

Studies point to the fact that ceramic brackets are chemically inert to the oral cavity, whereas polycarbonate and polyoxymethylene brackets may degradate releasing bisphenol-A and formaldehyde, respectively. In addition to the traditional cytotoxicity tests, the study of nitric oxide cellular production stimulated by a specific material has shown to be a reliable tool for evaluating its cytotoxic potential. The present study was aimed at assessing cellular viability by MTT {3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide} assay in a murine macrophage cell line J774 in the presence of esthetic brackets, and quantify nitric oxide production by these macrophages. Evaluation of cell culture was undertaken in three time intervals: 24, 48, and 72 hours. Cellular viability in all groups was higher at the final time interval (72 hours) in relation to the initial time (24 hours). This increase was significant in the control and ceramic bracket groups. Final means in the bracket groups did not show significant differences when compared to the control group. Nitric oxide production was significantly greater in all groups at the final time interval in relation to the initial time. There was no significant difference between the final means of the bracket groups and the control group, although polyoxymethylene brackets have shown significantly greater means at times 24 and 48 hours. In a second step of the study, macrophages were activated with gamma interferon (IFN-γ) in order to simulate a common condition of the human body in which these citocines are produced and released with the presence of antigens. Cellular viability in all groups was higher at the final time interval (72 hours) in relation to the initial time. Final means in the bracket groups did not show significant differences when compared to the control group. Nitric oxide production was significantly greater in all groups at the final time interval in relation to the initial time. However, there was not an increase of nitric oxide production in relation to the presence of brackets associated with the Interferon-Y stimulus.