Three Dimensional Comparison of Natural and Artificial Enamel Caries Lesions

Methods: Extracted permanent molar teeth were investigated. One tooth with a typical approximal white spot lesion and one lesion free tooth were selected. The artificial caries lesion was created by exposing a window on the enamel surface of the lesion free tooth to 0.1M acetic acid buffered to pH 4.5. A novel high-definition X-ray microtomography (XMT) scanner was used to scan the teeth samples at 30 micron resolution. The dataset was imported to Drishti visualisation software (Australian National University) to render normal enamel, dentine and enamel carious lesions in 3-D according to their respective linear absorption coefficients. The normal enamel and dentine were then made transparent to reveal the morphology of the carious lesions only. The differences in the morphologies of the two carious lesions were described.

Results: The natural caries lesion revealed a conical shape with the broad base at the natural surface and its apex towards the enamel dentine junction (EDJ). The artificial caries lesion had an even thickness of demineralisation from the enamel surface towards the EDJ.

Conclusions: The conical shaped natural caries lesion may be due to the contact of the lesion with adjacent tooth, forming an acid demineralising gradient from the centre to the perimeter. In the artificially induced lesion, as the whole surface was exposed to same concentration of acid, uniformity of demineralisation occurred resulting in an even thickness of the lesion.