Comparison of Nickel Ion Release and Corrosion Sites among Commonly Used Stainless Steel Brackets in Iran

One of the characteristics of brackets is resistance to corrosion. Corrosion could disturb dental movement through increasing, the friction between arch wire and slot. It could also cause dental discoloration. The aim of this study was to compare corrosion rate as well as corrosion site of five commonly used brackets in Iran. In this in vitro experimental study, 80 lower central stainless steel brackets (18- slot) from different companies (Mira, Dentaurum, Forte, Joli and 3M) were selected. At first, the brackets were mounted in Rapid impression material and the photographs were taken from six different views for assessing slots, bases, and wings using stereomicroscope device with X50 magnification. Then, each 8 brackets were put into a capped glass containing artificial saliva with PH=7.2 and they were incubated in 37±1°c temperature. The amount of released Nickel ion was measured by Atomic absorption technique after 6 weeks and for each bracket, photographs were taken again from previous views. Statistical analysis was done using Chi-square, Cochrane and Kruskal-Wallis and McNimar tests. The minimum Nickel ion release belonged to 3M brackets (0.86±0.1 PPB) and the maximum release was for Forte brackets (17.49±0.01 PPB). Furthermore, corrosion was seen more in bracket bases (mesh surfaces) and it was less observed in their faces. The order of the Nickel ion release was: 3M>Dentaurum> Joli> Mira>Forte. Corrosion was the highest in the base of the brackets.