The effect of a triclosan-containing (0.3%) dental gel on inflammatory mediators in gingival crevicular fluid (GCF) was evaluated in 14 healthy adolescents undergoing orthodontic treatment with fixed appliances. A double-blind randomized split-mouth study design was used with color-coded experimental and placebo gels. The gel was self-applied for 5 min twice daily for 14 days in custom-made soft plastic trays. Clinic al data (visible plaque index (VPI) and gingival bleeding index (GBI) and samples of GCF were collected at baseline and after 1, 2, 4, and 6 weeks. The concentrations of prostaglandin I2 (PGI2) and interleukin-1beta (IL-1beta were determined by radioimmuno- and enzyme-linked immunosorbent assays, respectively. No clinical effects of the gel applications regarding amount of plaque or gingival bleeding were unveiled. Neither the experimental nor the placebo gel applications caused any statistically significant alterations in the inflammatory mediators, PGI2 and IL-1beta, compared to baseline. In conclusion, the present study did not reveal any beneficial cffects of the triclosan-containing gel regimen on mild gingivitis in adolescents with fixed orthodontic appliances.