Comparative evaluation of nickel and chromium release from three different metal brackets in artificial saliva

Background and Objectives: Orthodontic brackets are important part of fixed appliances, which are used to deliver forces from the wires or other power modules to the teeth and will be in the oral environment for long periods of time. The most widely used stainless steel bracket in orthodontics is the austenitic type, containing 18-20% chromium and 8-10% nickel. The combination of chromium and nickel increases the bracket resistance to corrosion. The oral environment is highly conducive to corrosion and pH changes. Metallic orthodontic appliances are known to release metal ions leading to changes in the mechanical properties. Among the metal ions released nickel is the most common cause of metal-induced allergic contact dermatitis and second in frequency is chromium. The objective of this study is to compare and evaluate the rate of release of nickel and chromium ions from stainless steel brackets of three different manufacturers at two different time intervals. Methods: 90 standard stainless steel orthodontic brackets of three different manufacturers (Group A-3M ESPE, Group B- JJ Orthodontics, Group C-Modern Orhtodontics) were collected. The brackets were divided into three equal groups. Each bracket was incubated at a room temperature of 37°C in individual 30ml plastic containers containing 15ml of artificial saliva at pH 6.7. 2 ml of artificial saliva was taken from each plastic containers for inductively coupled plasma optical emission spectrometric (ICP-OES) evaluation on seventh day and twenty eighth day. The artificial saliva was replaced after each sample collection to avoid saturation with corrosion products. Result and Discussion: In all the three groups, Nickel release was more on seventh day. And chromium release was more on twenty eighth day for 3M and Modern. And for JJ Orthodontics, Chromium release was more on seventh day. Conclusion: Stainless steel brackets of 3M shows less amount of Nickel ion release on twenty eighth day compared to JJ and Modern. Stainless steel brackets of Modern shows less amount of Chromium ion release compared to 3M and JJ on both days.