Assessment the Release of Nickel Ion from Simulated Orthodontic Appliances for Orthognathic Patients and Comparison with Safe Level of Nickel

In orthodontic treatment,the various alloys are widely used. These materials are placed in contact with the oral tissues for months or even years. Microbiological and enzymatic properties of the oral cavity provide appropriate conditions for metals corrosion, causing the release of elements such as nickel, chromium, copper and silver from wires, bands and orthodontic brackets. The purpose of this study is to measure the amount of nickel ions released from the simulated appliance in orthognathic patients and compare the amount of releasing nickel with its safe level. In this semi-experimental study, 60 stimulated appliances in three different types (groups of 20) were studied. Theses three groups examined by spectophotometer to measure free nickel in artificial saliva using atomic absorption after 3, 6 and 2 months respectively and then calculated the rates of three groups, after that compared to safe nickel’s level. Statistical analysis was done by one sample t-test The mean and standard deviation rates of the released nickel in four quadrants of the oral cavity were 1198±533.45 in first group and 825.5±390.40 and 1290.5±455.47 microgram per picoliter in second and third groups, respectively. The mean amount of released nickel in all groups were less than the safe threshold (2500) and statistical analysis showed a significant difference (p<0.001). The amount of released nickel in the whole oral cavity (four quadrants) in each group was less than the toxic dose so this appliance may be safe.