Background <p>White spot lesions (WSLs) are initial caries caused by early demineralization. Nanohydroxyapatite (NHA) paste is one of the most recent non-fluoridated remineralizing agents; however, few clinical studies have reported its remineralizing effect on such lesions. The aim of this study was to compare and evaluate the remineralization and color change of WSL after NHA alone was used versus NHA pretreatment with either microabrasion or sodium hypochlorite (NaOCl) and no treatment as a negative control.</p> Methods <p>Twenty children aged 10 to 14 years with 40 teeth affected with WSL; were randomly assigned to 4 groups (10 teeth in each group); group I: pretreatment with microabrasion followed by NHA paste, group II: pretreatment with 5.25% NaOCl, followed by NHA paste, group III: NHA paste alone, and group IV: negative control with no treatment applied. The remineralization ability was assessed via diagnodent device and color changes were assessed via a Vita easy shade device before and after treatment; and one, two and six weeks after treatment.</p> Results <p>For the change in Diagnodent readings, there was a significant difference between groups (I, II, III) at different intervals, which as significantly greater than that of group IV at a p value &lt; 0.001. However, for Group IV, the change was not statistically significant (<i>p</i> = 0.332). The color changes measured after 2 and 6 weeks were significantly greater in groups (I), (II) and (III) than group IV (<i>p</i> &lt; 0.001).</p> Conclusions <p>NHA could be a good non fluoridated option to remineralize and improve the color of WSL at different treatment intervals. Pretreatment with microabrasion and NaOCl enhances its remineralization and color improvement properties.</p> Trial registration <p>This study was retrospectively registered on ClinicalTrials.gov at 6/2/2025, with ID: NCT06834464.</p>