BackgroundWhite-spot lesions are considered an initial carious stage characterized by an outer enamel layer with significantly reduced mineralization. This study was conducted to assess the combined effect of Biomin F toothpaste and Diode laser on remineralization of white spot lesions.Materials and methodsAn invitro study conducted on a total of 30 premolars divided into three groups; Group A (Biomin F Tooth paste), Group B (Biomin F with laser application for 30 sec), Group C (Negative control). The three groups were submitted to three stages; stage 1:Baseline,stage 2:After demineralization ,and stage 3:After remineralization. In each stage, elemental analysis(calcium, phosphorus, and fluoride)was measured quantitatively using Energy Dispersive X-ray (EDX) analysis and qualitatively by micrographs using scanning electron microscope. The data were tested to find significant difference between mineral changes during stages by using (ANOVA) test and Bonferroni test.ResultsCalcium, phosphorus and fluoride ions decreased in all groups after demineralization. In stage 3, after application of remineralizing agents, Calcium ions increased significantly in groups A and B where p<.05. As regards to the phosphorus ions, a significant increase was observed in all groups with group A showed the highest gain as phosphorus level percentage change (%mass) was 56.52±18.02 . Fluoride ions increased significantly in groups A and B (p<0.05) but decreased significantly in group C. There was no statistical significant difference between group A and B (p ≥.05) in calcium, phosphorus, and fluoride level after remineralization.ConclusionWithin the limitation of the present study, we concluded that Biomin F toothpaste is promising in the repairing of white spot lesions on the surface of the demineralized enamel. Diode laser did not affect the remineralizing ability of Biomin F toothpaste.