Study aim: This study evaluates whether the orthodontic retention phase can be used not only for tooth stabilization but also for treating white spot lesions, comparing green tea extract with CPP‑ACP as a more accessible natural option. Design: A randomized, triple‑blind, parallel‑group, controlled Phase 3 clinical trial conducted on 36 teeth in each intervention group (the study includes two intervention groups). Randomization will be performed using a random numbers table. Settings and conduct: This study will be performed in clinics affiliated with Isfahan University of Medical Sciences, including the TorabiNejad, Ghaedi, and Afzal clinics. Each patient receives two syringes: one contains CPP‑ACP or green tea and one placebo, applied nightly to the reservoir spaces. Lesions are measured with a DIAGNOdent Pen at baseline, 1 month, and 2 months. The study is triple‑blinded (patient, operator, and statistician). Randomizing the distribution of the sample is done using a random number table. Participants/Inclusion and exclusion criteria: Inclusion criteria: Age 15 to 30 years; Presence of at least one white spot lesion with a DIAGNOdent score between 10 and 20 on the corresponding teeth on both sides of one arch. Exclusion criteria: Systemic diseases, Tooth rotation, gingival hyperplasia, and tobacco use. Intervention groups: Intervention group Includes two subgroups of 36 teeth each with white spot lesions (DIAGNOdent 10–20). These teeth are treated with either green tea extract or CPP‑ACP paste. Comparison group Includes two corresponding subgroups of 36 contralateral teeth with the same DIAGNOdent range (10–20). These teeth receive a placebo. Main outcome variables: WSLs remineralization