UC Irvine

In this study, sound and carious dentin slices were visualized using a fluorescence technique and confocal laser scanning microscopy (CLSM). Twenty extracted human molar teeth showing no clinical signs of caries, and thirty additional teeth with pre-existing naturally occurring dentin caries were investigated. All teeth were horizontally sectioned to approximately 200 μm thickness and in forty sound sections from ten teeth, artificial caries-like lesions were induced for 3 days. All sections were pretreated with 5.25% sodium hypochlorite, vacuum and ultrasonication for one hour, then stained with Rhodamine 123 fluorescent dye at a concentration of 10-5 M in phosphate buffer saline for 3 h. Surface and subsurface images obtained using CLSM showed dentinal tubules in sound dentin and in artificial caries-like lesions which usually appeared open. Most dentinal tubules in carious dentin appeared obturated or narrowed. Thus, non-invasive surface and subsurface imaging of dentin structures is possible and useful using confocal laser microscope techniques, without the problematic invasive preparations required for scanning electron microscopy (SEM).