Hamad, D.K. and Hassan, B.A. 2018. Evaluation of Salivary Nickel, Chromium and Iron Ions in Patients Treated with Fixed Orthodontic Appliances in Vivo Study: in vivo study. Erbil Dental Journal (EDJ). 1, 2 (Dec. 2018), 109–116. DOI:https://doi.org/10.15218/edj.2018.15.