In-vitro study of the cellular viability and nitric oxide production by J774 macrophages with ceramic, polycarbonate, and polyoxymethylene brackets.
BACKGROUND
Studies show that ceramic brackets are chemically inert in the oral cavity, whereas polycarbonate and polyoxymethylene brackets can degrade, 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 been shown to be a reliable tool for evaluating its cytotoxic potential.


METHODS
We aimed to assess cellular viability by MTT (Sigma, St. Louis, Mo): 3,(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide assay in a murine macrophage cell line J774 with esthetic brackets and quantify nitric oxide production by these macrophages. Cell cultures were evaluated at 3 times: 24, 48, and 72 hours.


RESULTS
Cellular viability in all groups was higher at 72 hours compared with 24 hours. This increase was significant in the control and ceramic brackets groups. Final means in the bracket groups showed no significant differences compared with the control group. Nitric oxide production was significantly greater in all groups at final time. There was no significant difference between the final means of the bracket groups and the control group, although polyoxymethylene brackets showed significantly greater means at 24 and 48 hours.


CONCLUSIONS
Final means in the bracket groups showed no significant differences compared with the control group.
Vitral
Julia Cristina de Andrade
JC
Department of Orthodontics, Juiz de Fora Federal University, Juiz de Fora, Minas Gerais, Brazil.
Fraga
Marcelo Reis
MR
de Souza
Maria Aparecida
MA
Ferreira
Ana Paula
AP
Vitral
Robert Willer Farinazzo
RW
D000818:Animals; D002452:Cell Count / Q000379:methods; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003124:Colorimetry / Q000379:methods; D003764:Dental Materials / Q000737:chemistry / Q000633:toxicity*; D003776:Dental Porcelain / Q000737:chemistry / Q000633:toxicity; D005562:Formazans; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008422:Materials Testing / Q000379:methods; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D016910:Orthodontic Brackets; D011076:Polycarboxylate Cement / Q000737:chemistry / Q000633:toxicity; D012117:Resins, Synthetic / Q000737:chemistry / Q000633:toxicity; D018709:Statistics, Nonparametric; D013778:Tetrazolium Salts
D003764:Dental Materials; D005562:Formazans; D011076:Polycarboxylate Cement; D012117:Resins, Synthetic; D013778:Tetrazolium Salts; D003776:Dental Porcelain; C079782:MTT formazan; C005506:polycarbonate; D009569:Nitric Oxide; C010102:delrin