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Aim:The study aims is to investigate the combined effect of the corrosion and the fretting induced by small deflections imposed on the orthodontic stainless steel and nickel-titanium arch-wire in contact with stainless steel bracket in neutral artificial and acidified saliva which simulate the aggressive conditions. Materials and methods: Electrochemical analysis of orthodontic materials has been firstly conducted in the oral environment and under the combined effect of fretting and corrosion using an experimental test bench designed for this effect. Analysis of contact area between elements has also been conducted using scanning electron microscope (SEM) and energy dispensing spectroscopy (EDS). Results:The results indicate that the pH of an oral environment has an important influence on the corrosion resistance and the effect of fretting-corrosion process affects significantly the corrosion behavior of materials tested in the oral environment. Conclusion:The combined effect of fretting and corrosion tests conducted in artificial saliva show that nickel titanium wire is more resistant than stainless steel wire in contact with stainless steel brackets after 100000 cycles. Also, the corrosion resistance in acidified saliva is very pronounced for stainless steel wire and bracket as it reported by many authors. Clinical significance:The degradation of the orthodontics materials in the oral environment can cause major problems for the patient's health.