AngleOrtho cover optResults of a study published in The Angle Orthodontist show that orthodontic treatment is not a significant source of patient exposure to metal ions—specifically nickel, chromium, and copper. The study evaluated the release of metal ions from fixed orthodontic appliances.

To conduct the experiment, the researchers constructed a new system for in vitro testing of dental materials. The system consisted of a thermostatic glass reactor that enabled immersion of the studied material. Experimental conditions reflected the human oral cavity, with a temperature of 37° C and saliva flow rate of 0.5 mL/min.

A simulated fixed orthodontic appliance made of stainless steel was evaluated. The researchers performed sampling at several time points during the 28-day study, and the metal ion concentration was determined by inductively coupled plasma optical emission spectrometry.

The results show that the total mass of released metal ions from the appliance during 4 weeks of the experiment was 18.7 ?g of nickel, 5.47 ?g of chromium, and 31.3 ?g of copper.