Comparison of Stereomicroscopic Depth of Initial-caries Lesions Between Longitudinal-paired Hemisections

Objectives: To compare by means of stereomicroscopy the histologic depth of an initial-caries lesion between both sides of hemisected teeth
Methods: Given Ethical-Board approval and signed-consent forms, from a pool of extracted premolars an expert ICDAS-caries-visual criteria examiner selected teeth with 50 proximal ICDAS-2 caries lesions. These were longitudinally hemisected at the center of the lesion based on its surface appearance, using a diamond saw (Isomet-1000, Buehler®) (n=100). Images of hemisections were captured using a stereomicroscope (Olympus-SZ2-ILST®). Images were labeled as left image if the lesion could be seen at the left side of the screen and conversely for right-side images. Using the Motic-Images-Plus-2.0 software® 3 examiners by agreement calculated on the images, drawing ruled lines (μm) over the image, the enamel width at the lesion area marking the external point correspondent to center of the lesion and the enamel-dentin junction (EDJ) following the center of the lesion, and the maximum lesion depth starting at same external point and following same direction. For each hemisection the software gave two length measures (μm) that were registered in an Excel-Microsoft-software sheet. Statistical analysis was conducted by calculating differences of lesion depth between hemisections (U-Mann Whitney test)
Results: One hemisection was lost during the cutting process (n=99). Most lesions were located between inner-enamel half and EDJ (46.46%), followed by outer-enamel half (39.39%), outer-dentin third (9.09%), and middle-dentin third (5.06%). Carious lesions had an average depth of 604.98 ± 365.14 μm for left- and 664.35 ± 719.78 μm for right-side images. No significant difference in the lesion depth was found between hemisections (p>0.05)
Conclusions: By dissecting teeth at the visual center of the surface lesion both hemisections can be used for in vitro histologic studies, without statistically significant differences in the caries-lesion depth