Objective: The aim of the study was to evaluate microscopic appearance and mineral content of early caries lesions on smooth teeth surfaces. Methods:The sample comprised 10 teeth, exhibiting spot lesions, which had been extracted for orthodontic or periodontal reasons and obtained from 14 to 30 years-old subjects. The teeth were sectioned and tooth tissues destruction and demineralisation were evaluated in vitro using SEM (Joel JSM 5800 LV) and quantitative microradiography by EDS (Oxford ISIS 300) using atomic weights and comparative elements percentage between the different sample sites were calculated. A longitudinal section of the tooth was performed through the site where the changes on the macroscopic photograph were found. A longitudinal section of the same tooth at sound tissue near the location of the early stages of caries was investigated.

Results: Data show that enamel with spot lesion exhibit compositional differences from sound enamel namely the body of the prisms were hollowed out and in some cases the changes of the shape were observed leading to rhomboid crystals. Microanalytical research has shown that the earliest material to be removed during carious attack appears to have high concentration of carbonate and magnesium, both of which are known to increase enamel solubility. The following changes of the chemical composition were observed in caries point compared with sound enamel (the material lost during the earliest stages of carious attack): DCa: - 34%; DP: - 20% ; DMg: - 2% ; DNa: - 1% Conclusion: It should be concluded that SEM and EDS are techniques which supplement each other in the analysis of the enamel destruction. The results show that enamel with early caries lesion exhibit compositional differences from sound enamel which could potentially be used to develop diagnostic and monitoring techniques.

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