Calibration of a measurement technique by inclusion of multiple standards ensures validity of results. The use of multiple standards allows for quantification, estimates of standard error, and limits of detection. These factors are essential for interlaboratory comparison. The use of citric acid solutions and water as a series of standards provides means to compare relative mineral loss among dental erosion methods.
Objective: Quantitatively evaluate mineral loss from human enamel after exposure to erosion standards of citric acid at CA1.0%, CA0.25%, CA0.07%, and CA0.0%.
Method: Human permanent teeth were sectioned and thinned to 110µm thickness. For an alignment reference point, transmission microscope grids were attached at the dentin-enamel junction. Teeth were mounted into epoxy between coverslips, tooth surfaces were polished to 1200 grit to remove the outer layer and expose fresh enamel. Samples were then subjected to one of the CA concentrations for either one or four hours (n=6). Erosion loss of enamel after exposure was measured by comparison of pre-treatment and post-treatment images of 30x or 75x captured with a digital microscope camera (sensitivity=±2µm/pixel at 30x; 1.2µm/pixel at 75x).
Results: Significant differences in erosion loss were measured between CA0.0%, CA0.25%, and CA1.0% for both one and four hour treatments (p<0.05). Each standard curve was linear with r2 of 0.9907 and 0.9704 for one and four hours.
CA Conc. % | 1 hour Average±S.D. (µm) | 4 hour Average±S.D. (µm) |
0.00 | 0.7±1.7* | -2.7± 4.1** |
0.07 | 0.7±0.5* | 3.7± 8.4** |
0.25 | 9.7±3.5 | 22.6± 8.3 |
1.00 | 24.6±1.5 | 71.1±22.8 |
Asterisks indicate no significant difference (p>0.05) between CA0.0% and CA0.07%.
Conclusion: This microscope based erosion determination method could distinguish between CA standards. This study demonstrates the importance of including multiple standards in experimental design. Increasing exposure time from one to four hours allowed for an increase in the sensitivity of relative erosion for this method between CA standards.