Three-dimensional reconstruction of approximal subsurface caries lesions in deciduous molars

The present study examines the three-dimensional (3D) morphology of early approximal subsurface enamel caries lesions and subjacent dentin reactions in deciduous molars. Twenty-three extracted primary molars were embedded in Technovit 9100 and serial sections were cut using a saw microtome. Forty approximal lesions were found and investigated using polarized light microscopy for the identification of the different zones of the caries lesion. These zones were then reconstructed three-dimensionally using computer-aided 3D reconstruction methods and the dimensions and volumes of the translucent zone, the body of the lesion, and the dentin lesion were calculated. The enamel demineralization index was defined as the ratio between the translucent zone and the body of the lesion, whereas the enamel-dentin demineralization index was defined as the volumetric ratio of the early dentin lesion to the body of the enamel lesion. The 3D reconstruction of the lesions showed extremely heterogeneous micromorphological features of zone profiles. In enamel lesions, the results demonstrated a decreasing enamel demineralization index with increasing size of the lesion, which indicates a high risk of further caries progression. The enamel-dentin demineralization index indicated, in 5 out of 17 dentin lesions, a high risk of further caries progression. Computer-assisted 3D reconstruction and volumetric assessment of initial caries lesions in deciduous molars represents a valuable methodology in pathogenesis studies, which may lead to a better clinical understanding of caries progression.