Measurement of Erosion Depth using Microcomputed Tomography and Light Microscopy

Objectives: Dental erosion is the surface loss of dental hard tissue mostly associated with an acid attack not from bacterial origin. The aim was to compare dentin and enamel erosion depth measurements using micro-computed tomography and light microscopy.
Methods: Enamel and dentin blocks were prepared from caries-free human extracted molar teeth (N=12). Teeth were sectioned and the crown portion cut to a rectangular shape of 4 x 4 x 6 mm. Enamel specimens were painted with nail-varnish to expose a flat 2 x 4 mm window (N=12). Root portions were used to prepare dentin specimens (N=12) the same way as for enamel specimens. Specimens were treated with water (NC) or 1.0 % citric-acid solution (CA). After treatment, specimens were scanned with microCT (Bruker, Kontich / Belgium). On completion of scanning, specimens were sectioned and observed under a light-microscope (LM). Lesion depth was observed with 10 times magnification and images transferred to Simpleware (Synopsys,INC., Exeter, Devon / UK). Vertical distance from lesion surface to bottom was measured at three different points and averaged. Pearson correlation test was used to evaluate correlation and Wilcoxon Signed Rank test to evaluate differences in the two analysis methods.
Results: Mean enamel erosion depth was 0.63 µm and 38.38 µm (microCT) and 0.54 µm and 39.43 µm (LM) for NC and CA, respectively. Dentin erosion depth was 0.72 µm and 48.05 µm (microCT) and 0.56 µm and 49.92 µm (LM) for NC and CA, respectively. There was a significant correlation between the two analysis methods (r=0.998). No statistically significant difference in results were obtained from the two methods (p=0.584).
Conclusions: Erosion depth measurements made using microCT and light microscopy yielded comparable results. The microCT method is a non-destructive technique and is preferred if the conservation of specimens is desired.