Characterization of healthy and fluorotic enamel by atomic force microscopy

The aim was to characterize the external structure, roughness, and absolute depth profile (ADP) of fluorotic enamel compared with healthy enamel. Eighty extracted human molars were classified into four groups [TFI: 0, control (C); 1-3, mild (MI); 4-5, moderate (MO); 6-9, severe fluorosis (S)] according to the Thylstrup-Fejerskov Index (TFI). All samples were analyzed by atomic force microscopy.The mean values of enamel surface roughness (ESR) in nm were: Group C, 92.6; Group MI, 188.8; Group MO, 246.9; and Group S, 532.2. The mean values of absolute depth profile in nm were: C, 1,065.7; MI, 2,360.7; MO, 2,536.7; and S, 6,146.2. The differences between mean ESR and mean ADP among groups were statistically significant (p < 0.05). This structural study confirms at the nanometer level that there is a positive association between fluorosis severity, ESR, and ADP, and there is an association with the clinical findings of fluorosis measured by TFI as well.