Validity and reliability of a questionnaire assessing Brazilian adolescents' experiences in orthodontic treatment.

The study aimed to validate a questionnaire for the Brazilian adolescent population assessing patient's perceptions of orthodontic treatment and to verify whether its original psychometric properties were preserved during the transcultural adaptation process. A total of 160 adolescents, assessed before and after orthodontic treatment at two different orthodontic clinics,answered a self-administered questionnaire translated into Portuguese. Patients were equally assigned to two groups: non-treated adolescents (NTA) and adolescents receiving orthodontic treatment (AOT). Both male and female adolescents were selected (age range: 12 to 17 years). A trained orthodontist examined all patients to record the aesthetic dental index (ADI) and the decayed, missing, and filled teeth (DMFT) index. The adolescents' legal guardians answered a socioeconomic questionnaire. Reliability was assessed by evaluating the instrument's internal consistency and stability, using Cronbach's alpha, the intraclass correlation coefficient (ICC), and Cohen's kappa coefficient (k). Construct validity was assessed through cross-cultural validation and hypothesis testing. Cronbach's alpha was 0.7 for the NTA group and 0.9 for the AOT group. The instrument demonstrated excellent stability for the NTA group, yielding an ICC > 0.9. The k values showed a strong to almost perfect correlation (between 0.701 and 0.999) for the AOT group. The Brazilian version of the QPAOT proved to be a reliable and stable instrument, with good psychometric properties and can therefore be considered an appropriate instrument for assessing adolescents' perceptions and expectations regarding orthodontic treatment.