Clinical observations on the nature of early caries. A study with scanning electron microscopy

BACKGROUND: Early caries lesions present a greater porosity in the deep layers than in the superficial layer of the enamel. The "white spot" lesion is a dynamic lesion which is subjected to the changes occurring in the oral cavity; it can regress, stabilize or progress. The aim of this study is to show if there are considerable morphological differences in the superficial ultrastructural aspect of early caries lesions, active or stabilized, in persons of different age. METHODS: To carry out this SEM observation, 15 patients aged from 12 to 50 presenting early caries lesions have been selected. Some of them had been recently subjected to orthodontic treatment, others several years ago. Five of these patients have been called back to examine again the demineralized area by microscope in the very same place of the first observation. The replica technique was used utilizing a silicon-based impression material, an epoxy resin for replicas casting, little steel nets to fix the silicon material. RESULTS: At the level of white spot lesions it is evident a tissural structure scattered with small overlappings and micropits with a diameter of 0.5-2 mu. The patients who removed orthodontic bands more than 10 years before show a shining white aspect, corresponding to the nearly complete loss of enamel perikymata with well defined abrasions, but without any micropits at SEM examination. CONCLUSIONS: The replica technique has shown to be useful to record the defects of active and stabilized caries lesions. However this technique can't be utilized as a diagnostic instrument because it would be too expensive, but it is certainly a valid support for in vivo research.