Comparative clinical evaluation of Icon resin infiltration and Vanish XT varnish for managing white spot lesions: a randomized controlled trial

White spot lesions (WSLs) are a common esthetic concern. This study compared the clinical efficacy of Icon® resin infiltration (RI) and Vanish™ XT varnish (Vanish XT) in improving WSL appearance. A single-blinded randomized controlled trial was conducted on 138 WSLs in 33 children aged 7–14 years. Participants were randomly assigned (1:1) to receive Icon® RI (n = 75) or Vanish XT (n = 63). Lesions were evaluated at baseline (T0), immediately post-treatment (T1), and after 12 weeks (T2). Objective color changes were measured using the CIE L*a*b* system, while subjective esthetic improvement and opacity reduction were assessed using a visual analog scale (VAS). The Icon® group demonstrated significantly greater reduction in color mismatch relative to adjacent sound enamel at T1 (ΔE = 2.34 ± 0.5) compared with the Vanish XT group (ΔE = 6.35 ± 1.2, P < 0.05). However, these findings should be interpreted with caution, as measurements at T1 may have been influenced by transient enamel dehydration. At 12 weeks, the Icon® group continued to demonstrate lower ΔE values than the Vanish XT group (ΔE = 4.69 ± 0.7 vs. 8.50 ± 1.3, P < 0.001). VAS scores were significantly higher for the Icon® group in both esthetic satisfaction and opacity reduction (P < 0.01). Minor surface staining occurred in two Icon® cases at follow up but did not affect overall esthetic perception. Within the short follow-up period, Icon® RI demonstrated improved esthetic outcomes compared with Vanish™ XT, with differences observed in color parameters and subjective assessments. However, conclusions regarding long-term color stability remain limited. This trial is registered in November 2024 at ClinicalTrials.gov (Identifier: NCT06696105).