To investigate the impact of written instructions, about post-bonding pain, on patients' pain perception and analgesic consumption and to evaluate the correlation of pain with personality types. Two-arm parallel randomised controlled trial. University Hospital Centre Zagreb, Zagreb, Croatia. Participants included adolescents in the permanent dentition with mild or moderate crowding. The participants were randomly allocated, using computer-generated random list, into two groups. After bonding and archwire insertion, all participants received oral instructions on potential pain occurrence and pain control. Participants in the study group also received written information on post-bonding pain. Pain intensity was evaluated using the Numerical Rating Scale immediately after (T0), 2 days (T1) and 7 days (T2) after the placement of the fixed orthodontic appliance. Analgesic consumption was assessed as yes or no, and personality traits were assessed using the Big Five Inventory. Operators who scored pain intensity and recorded analgesic consumption and personality traits were blinded to the group allocation. Statistical analyses included the t-test, Mann-Whitney U-test, Spearman correlations and stepwise regression analysis. The highest rate of pain was recorded at T1 (P < 0.001). No statistically significant difference in pain perception between groups was observed. There was no statistically significant difference in analgesic consumption between the two groups (P = 0.81). The correlations between personality traits and pain perception were not significant. The additional written information had little impact on pain perception, and it had no relationship to personality types. The perception of pain and analgesic consumption were not affected by the provision of additional written information (P = 0.81). Participants' personality types did not affect the impact of the information given.