Is the Peer Assessment Rating index a valid measure for change in Oral Health-Related Quality of Life following orthodontic treatment? Results of a cohort study.

Objectives: To explore the relationship between changes in Peer Assessment Rating (PAR) score and Oral Health-Related Quality of Life (OHRQoL) following orthodontic treatment and to assess responsiveness of the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) in a cohort of young adults.

Materials and methods: Participants (n = 162) aged 18-25 years requiring comprehensive fixed orthodontic treatment were recruited. Changes in OHRQoL were measured using the PIDAQ, while malocclusion severity was assessed using the PAR index and Index of Orthodontic Treatment Need. Data were collected before treatment (T0) and 1 month after treatment completion (T1). Responsiveness of the PIDAQ was evaluated using standardized effect size, standardized response mean, and Global Transition Judgment.

Results: A positive, moderate overall correlation (r = 0.417, P < .05) was observed between changes in PAR and PIDAQ scores posttreatment, with significant improvements in OHRQoL reported by 88.1% of participants at T1. Subgroup analysis revealed strong correlations in cases of crowding (r = 0.711) and increased overjet (r = 0.703), while Class III malocclusion showed a weaker correlation (r = 0.263). Multivariate regression analysis revealed that change in PAR score was independently associated (R2 = 0.652) with change in OHRQoL score. The PIDAQ demonstrated responsiveness to treatment-associated changes, with a significant reduction in OHRQoL scores posttreatment.

Conclusions: While a positive correlation between the objective measure of malocclusion severity (PAR) and subjective OHRQoL was identified, the relationship was moderate. The PIDAQ was found to be a responsive scale for assessing OHRQoL in orthodontic patients.