Microradiography and electron microprobe analysis of some natural white and brown spot enamel lesions with and without laminations

Extensive ‘white spot’ and ‘brown/white spot’ lesions with intact surfaces in 11 molars were investigated by microradiography and electron microprobe analysis for Fe, Ca, Na and Cl. At the surface of the brown spots some Fe was found. Within the lesions a preferential dissolution of Na and a slight enrichment of Cl was found. This suggests that Na and Cl are sited in different parts of the mineral and the Na-containing part appears to be more soluble. The Na and Cl contents of a lamination approach those of adjacent sound enamel. This indicates that laminations do not result from major reprecipitation of a less soluble calcium phosphate within the formed lesion, but that the mineral is protected from local dissolution early in the process. A possible mechanism is discussed.