A comparison of orthodontic pain between invisalign aligner and fixed appliance treatment

Objective To compare pain and discomfort during the first week of orthodontic treatment between patients treated with Invisalign aligners (IA) and those treated with fixed appliances (FA), and to describe baseline expectations and psychological measures. Materials and Methods This prospective, longitudinal, non-randomized cohort study enrolled 37 consecutive orthodontic patients aged 18–35 years; 18 (9 men, 9 women) selected IA and 19 (9 men, 10 women) selected FA. Baseline assessments included an Expectation Questionnaire (EQ), the Modified Dental Anxiety Scale (MDAS), the Spielberger State–Trait Anxiety Inventory (STAI), and the Pain Catastrophizing Scale (PCS). Pain and discomfort were separately recorded using 0–10 visual analogue scales (VAS) at baseline and at 2, 6, 12, 24, 36, 48, 72, 120 and 168 hours after appliance placement. Participants were advised not to use analgesics and none reported analgesic use during the observation period. Data were compared using Fisher’s exact test for categorical variables, Mann–Whitney U test for non-normal continuous variables, and one-way ANOVA for mean VAS comparisons at individual time points; area under the curve (AUC) was calculated for weekly VAS trajectories. Results Patients who chose IA expected less pain than those who chose FA (p = 0.03), whereas patients who chose FA placed greater importance on lower cost (p < 0.01). Compared with FA, the IA group reported significantly lower VAS-Pain at 24 h (p < 0.01), 36 h (p < 0.01) and 48 h (p = 0.03). The IA group reported higher VAS-Discomfort at 2 h (p = 0.01) and 6 h (p = 0.05), and lower values at 36 h (p = 0.04) and 48 h (p = 0.02). The FA group had a larger pain AUC (25.61 vs 18.25). Psychological scores (MDAS, PCS, STAI) did not differ significantly between groups (p ≥ 0.118). Although psychological variables were collected, multivariable longitudinal adjustment was not performed and is acknowledged as a limitation. Conclusions In this prospective, non-randomized cohort, adults who selected IA experienced less pain over much of the first week after appliance placement but greater immediate discomfort in the first hours after insertion compared with those who selected FA. Baseline expectations and cost concerns influenced treatment choice. Randomized trials and adjusted longitudinal analyses are required to establish causal relationships.