White spot lesions develop as a result of a dietary carbohydrate and saliva modified bacterial infection, resulting in an imbalance between demineralisation and remineralisation of enamel. The lesion is caused by the accumulation of plaque and bacteria along with insufficient oral hygiene. High plaque accumulation can increase the risk of white spot lesion formation. The dynamic balance between demineralization and remineralization determines the progression of white spot lesion. The diagnostic armamentarium includes novel technologies and non-invasive techniques like fiber-optic transillumination and electrical resistance methods which are very useful in detecting posterior approximal dentinal caries and occlusal caries. Radiographs and direct digital imaging are still important tools in the estimation of caries. A clear understanding of the mechanism of subsurface lesion formation and progression, possibilities, and limitations of newer methods and their clinical applications need to be recognized by the dentist to direct preventive strategies to the high caries risk individuals.