Irregularities below the enamel-dentin junction may predispose for fissure caries

This study investigated the structure of the fissure fundus on occlusal surfaces with respect to the detection of possible irregularities below the enamel-dentin junction (edj). occlusal surfaces were examined by micro-computed tomography (μct). in total,203 third molars with clinically sound occlusal fissures or non-cavitated lesions were selected. all specimens were scanned with μct. subsequently,each tooth was sectioned,and each slice was investigated by stereomicroscopy. in 7 of 203 molars (3.4%),demarcated radiolucencies below the edj were detected by μct. these defects were obviously of non-carious origin,because the μct images revealed no gradient of demineralization in the dentin. in all cases,a direct pathway between the oral cavity and the dentin was evident. the comparison of the μct sites with conventional histological images also revealed defects in the dentin. these results demonstrate that demarcated radiolucencies below the edj may not necessarily be caries lesions according to μct images and may be classified as possible developmental irregularities. to avoid misinterpreting μct data,dental researchers should carefully consider this condition when analyzing μct images. the clinical significance of this finding is that these defects may predispose molar teeth to early-onset caries in occlusal pits and fissures. © 2012 international & american associations for dental research.