Longitudinal assessment of the impact of orthodontic treatment on adolescents' quality of life: a comparison between boys and girls using a condition specific questionnaire.

The aim of this study was to compare the impact of the first year of wearing of a fixed orthodontic appliance on the Oral Health-Related Quality of Life (OHRQoL) between boys and girls, by means of a condition-specific instrument. The study included 69 adolescents aged 10 to 18 years, who were undergoing orthodontic treatment with a fixed appliance. Of the 69 adolescents, 38 were girls (55.1%) and 31 were boys (44.9%). They answered the Brazilian version of the Impact of Fixed Appliance Measure (B-IFAM) questionnaire three months (T1) and one year (T2) after the fixed appliance was installed. This questionnaire contains 43 questions, distributed across nine domains. The higher the scores, the more negative the perception of the adolescent concerning the impact of the fixed appliance on his/her OHRQoL. Sociodemographic and clinical variables were also analyzed, and statistical analysis was performed. For the domains, the effect size (the magnitude of the difference between girls and boys) and the minimal clinically important difference were also calculated. The adjusted regression showed that there was a significantly greater increase in the overall B-IFAM score in girls than in boys, indicating a more negative perception of the OHRQoL over the study time [Coefficient=11.77 (3.47- 20.60), p=0.006]. From T1 to T2, there was a significantly greater increase in the scores (more negative perception of OHRQoL over time) in girls than in boys for the domains aesthetics (p=0.034) and physical impact (p=0.011). These differences were clinically significant. The effect size (the magnitude of the difference) was moderate. The impact of wearing a fixed appliance on the OHRQoL was more negative in girls than in boys during the first year of orthodontic treatment.