Clear aligners versus removable appliances in mixed dentition: short-term pain, anxiety, and oral health outcomes—a prospective cohort study

Background Early orthodontic treatment during mixed dentition may influence children’s pain, anxiety, and oral hygiene. This study compared these outcomes in children treated with clear aligners or conventional removable appliances. Methods This prospective observational cohort study included 24 children aged 6–12 years with anterior dental crossbite who received clear aligners ( n = 12) or conventional removable appliances ( n = 12). Treatment allocation was non-random and determined as part of routine clinical care. All participants received standardized oral hygiene education before appliance delivery. Trait anxiety was assessed pretreatment using the trait subscale of the State-Trait Anxiety Inventory for Children (STAI-C). Pain and state anxiety were assessed on days 1, 3, 7, and 14 using the Visual Analog Scale and STAI-C state subscale, respectively; Plaque Index (PI) and Gingival Index (GI) were assessed pretreatment and on day 14. Two-way mixed ANOVA with Bonferroni-adjusted comparisons was used. Results No statistically significant between-group differences were detected in the measured pretreatment characteristics, including trait anxiety. Pain and state anxiety showed significant time, treatment, and time × treatment interaction effects. Compared with clear aligners, the removable appliance group reported higher pain on day 3 (mean difference 1.50, 95% CI 0.67 to 2.33), day 7 (2.58, 1.76 to 3.41) and day 14 (1.00, 0.33 to 1.67), and higher state anxiety on day 3 (7.92, 4.79 to 11.05) and day 7 (5.75, 2.81 to 8.69), but not on day 14 (2.17, − 0.17 to 4.51). Plaque Index and Gingival Index decreased in both groups, with lower day-14 values in the clear aligner group; however, the Time × Intervention interactions were not statistically significant, indicating no evidence of between-group differences in changes over time. Conclusions During the initial 14-day adaptation period, clear aligners were associated with lower pain on days 3, 7, and 14 and lower state anxiety on days 3 and 7 compared with conventional removable appliances. PI and GI decreased in both groups, with no statistically significant between-group differences in changes over time. These findings should be interpreted cautiously given the small sample size, single-center setting, non-randomized treatment allocation, and short follow-up period. Trial registration ClinicalTrials.gov, NCT07331090; retrospectively registered on 9 January 2026.