A polarized light microscopic study of progressive stages of enamel caries in vivo

To examine the gradual development of ‘white spot’ carious lesions in vivo, orthodontic bands were placed on 4 permanent premolars in each of 3 voluntary individuals undergoing orthodontic treatment. A standardized space was made between the bands and the buccal surface to ensure accumulation of dental plaque. The 4 premolars were removed from each individual 1, 2, 3 or 4 weeks after placement of the band. After 4 weeks ‘white spot’ lesions with subsurface demineralization were observed in all individuals. After 1 week initial demineralization occurred as an outer translucent zone in polarized light, while the 2- and 3-week specimens showed varying degrees of subsurface demineralization. Quantitative assessments of tissue porosity disclosed in all stages of lesion development that the outer 3–9 μm of the surface remained less porous than the immediately underlying tissue.