In vitro release of nickel and chromium from new stainless steel brackets into simulated oral environment at different pH, and under manual brushing

Objective: To examine the effects of three different parameters—pH value, brands of bracket, and role of brushing—on release of metal ions from orthodontic appliances. Materials and Methods: Simulated fixed orthodontic appliances which consist of brackets with covered base were immersed in artificial saliva of different pH values (4.2, 6.5 and 7.6) during 28-day period. Three different brands of stainless steel brackets were used: Gemini(3M), Abzil(3M), Orthox(JJ ortho) series. All the brackets embedded in self cure and the effect of brushing on ions release have been evaluated. The quantity of metal ions was determined with the use of a Atomic absorption spectrophotometer. Results: The release of Nickel and chromium ions were observed. Results showed that (1) The Ni and Cr released from all the brands of brackets; (2)The change in pH had a strong effect on the release of ions; and (3) When compared between brushing and non brushing group maximum amount of Ni and Cr released from brushing group at all the days. Conclusion: Levels of released ions are sufficient to cause delayed allergic reactions. This must be taken into account when different brand of brackets is selected, especially in patients with hypersensitivity or compromised oral hygiene.