The present study aimed to compare clinical, fiber-optic transillumination and bite-wing radiographic assessment of carious lesion depth in contacting proximal surfaces with the results obtained by direct visual inspection after tooth separation of the respective surfaces. It is suggested that when a carious lesion is diagnosed as non-cavitated by clinical examination or restricted to enamel by FOTI or radiographic examinations in a population of children with low caries prevalence, dentists should adopt a preventive approach.