© 2019 by Turkish Orthodontic Society - Available online at turkjorthod.orgObjective: We assessed pain and anxiety using psychological testing instruments (State-Trait Anxiety Inventory for Children, visual analog scale) and a physiological testing instrument (salivary cortisol hormone level) after the insertion of orthodontic appliances and during the initial alignment phase of orthodontic treatment. Methods: The study group involved two groups matched according to age and gender. Group 1 used 0.016-, 0.016×0.016-, and 0.16×0.22-inch and Group 2 used 0.014-, 0.016-, and 0.016×0.016-inch superelastic nickel-titanium archwires in the initial alignment phase of treatment. Pain and anxiety instruments were applied, and saliva samples were collected from the patients before and after molar band insertions, and bracket and initial archwire placement, and 7 days after the initial bonding and archwire replacements. Results: Cortisol levels and state anxiety scores revealed statistically significant differences within groups (p<0.01, p<0.05). No significant differences were found between Group 1 and Group 2 in cortisol hormone levels, anxiety scores, or pain measurements (p>0.05). Although not statistically significant, the most severe pain was measured in the posterior teeth after band insertion and in the anterior teeth after the first archwire insertion (p>0.05). Conclusion: Orthodontic appliances and the initial alignment phase of orthodontic treatment affect patients' anxiety and cortisol hormone levels. Both archwires were equally effective with regard to perceived pain, anxiety, and stress hormone levels.