Dental fluorosis has been widely studied, but the physical properties of fluorosed enamel is not well known. Objective: In this pilot study we wanted to assess variations in microhardness of tooth surfaces with different degree of fluorosis. Method: Shed human primary canines and molars were collected in Ethiopia during 1998-2000 in areas with high concentrations of fluoride in drinking water. Teeth were grouped according to the degree of fluorosis (Thylstrup-Feierskov index, TFI). Fifty seven teeth were selected for microhardness testing (Vicker's Hardness, HV) using a Leica DMIRM equipment. The measurements were made on the facial surfaces of the teeth. Three to four indentations were made in the selected area of each tooth. Mean values were calculated. Results: Teeth with TFI 0 (no fluorosis) had significantly harder enamel than teeth with fluorosis (P<0.001, Student’s t-test). This was also true for the molars alone. The same tendency was found for canines, but the association was not statistically significant. The teeth with TFI 1-4 had higher HV scores than the teeth with TFI 5-7, however, the difference was not statistically significant. The table shows the microhardness (HV) of tooth surfaces according to TFI, and the number of teeth (n).
| | Canines | Molars | Total |
| TFI 0 | 274 (n=5) | 302 (n=6) | 289 (n=11) |
| TFI 1-4 | 224 (n=22) | 176 (n=10) | 223 (n=32) |
| TFI 5-7 | 179 (n=8) | 165 (n=6) | 173 (n=14) |
Conclusion: Non-fluorotic teeth showed significantly higher microhardness than fluorotic teeth. (Supported by the Research Council of Norway).