Metal ions accumulate inside the epithelial cells of the oral mucosa and damage the DNA. The aim of this study was to analyze whether DNA damage and/or apoptosis also occurs after a short-term exposure to the metals of fixed orthodontic appliances. 23 subjects were enrolled in the test group and 8 patients in the control group. Analyses performed on samples of oral mucosa were cell count, cellular viability, quantification of intracellular metal concentration, comet and micronuclei tests and quantification of intracellular Glutathione (GSH). The obtained results indicated that orthodontic appliances release metal ions, especially chromium, that cause inflammatory processes leading to DNA damages. These phenomenon are visible only after 30 days from application of fixed orthodontic appliances.