Fluoride`s effect on the surface roughness of developing enamel crystals

It has been shown that the detrimal effects of high doses of fluoride occur during the late transition and early maturation stage of enamel development. It has been proposed that these detrimal effects are caused by the delayed removal of enamel proteins resulting in impairment of enamel crystal growth. We have reported that this delayed removal may be caused because the surface of fluorotic enamel crystals are rougher than non fluorotic crystals and, therefore, bind ameloblastin and amelogenin more tightly. statistically Objective: To establish whether the surface roughness of fluorotic crystals was dose dependent and whether crystals from both the transition and maturation stages of enamel development are effected in a dose dependent manner. Methods: Enamel crystals were obtained from developing mandibular incisors of Wistar rats. Litter mates were raised either in the absence of fluoride (control) or with 25, 50, 75 ppm fluoride administered in the drinking water. Both maturation and transition stage enamel were microdisected from the developing incisors. Roughness measurements (RMS) were obtained for the crystals after imaging on a Nanoscope IIIa Multimode Atomic Force microscope (AFM) in tapping mode. Results: Both maturation and transition stage fluorotic enamel crystals showed statistically increased surface roughness when compared with the non-fluoride controls and the RMS for 75 ppm dose was statistically greater than that for the 25 and 50 ppm dose. No difference was seen between 25 and 50 ppm in both groups. (Maturation stage enamel RMS: control, 0.53±0.18; 25 ppm, 0.65±0.21; 50 ppm, 0.71±0.20; 75 ppm, 0.85±0.28. Transition stage RMS: control, 0.5±0.16; 25 ppm, 0.85±0.27; 50 ppm, 0.86±0.32; 75 ppm, 1.07±0.35). Conclusion: Surface roughness of fluorotic crystals in both maturation and transition stage enamel depends on the fluoride concentration when administred systemically and increases as the fluoride concentration increases although this effect is not linear.(IADR.CED Visiting Scholar Stipend)