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The effect of fluoride varnish and solution on initial enamel erosion was studied. Enamel specimens prepared from human third molars were treated for 24 h with Duraphat® varnish (2.26% F) or for 48 h with NaF solution (1.2% F), washed, and immersed in cola beverage (pH 2.6) for up to 15 min. The surface microhardness was measured using a Vickers diamond in a Leitz indentation apparatus at baseline, after fluoride treatment, and after 1, 5, and 15 min exposure to acidic drink. The specimens were then prepared and studied using a JEOL JSM–35 scanning electron microscope. The results showed that both fluoride treatments caused an increase in enamel hardness values and subsequent inhibition of softening which was statistically highly significant. Scanning electron micrographs revealed the difficulty of removing Duraphat varnish from the enamel surface, and remnants of varnish were seen irrespective of vigorous sonication in acetone. However, in areas devoid of varnish, erosion was observed as mainly irregular lesions similar to those seen in the NaF solution treated and control specimens. The present study showed that treatment of enamel with topical fluoride prior to acidic challenge can inhibit initial erosion.

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Young Osborne-Mendel rats were given different diets for 6 weeks. Effects of soft and rough food as well as acidic sport drink on the lingual surfaces of first mandibular molars were studied. In addition, the effect of fluoride on erosion was examined. A Jeol JSM-35 scanning electron microscope was used to visualize tooth surface ultrastructure. Intact surfaces were found in the rats given soft food and distilled water. Sport drink (pH 3.2) caused severe erosion with total loss of supragingival enamel and exposure of dentin. Attrition effects were seen on the cuspal parts of the surface when rough food was given. Tooth tissue loss was greatest in the rats given rough food and sport drink; signs of both erosion and attrition could be seen. When fluoride was added to the sport drink erosion lesions were less severe and if dentin was exposed, the dentinal tubules were partly occluded. These SEM observations support earlier studies which have suggested that erosion may alter tooth surface so that it is more susceptible to attrition; in those lesions, however, clinical diagnosis of the initial causes may be difficult.

– A sport drink mixture (pH 3.2), either as such or supplemented with 15 ppm F or 38.5 ppm Mg or both, was given to Osborne‐Mendel rats as the only liquid for 42 days. The erosion was scored on the lingual surfaces of the first mandibular molar teeth. Sport drink caused marked erosion, but in the groups where fluoride, alone or with magnesium, was added to the drink, the erosion damages were less severe. Magnesium alone had no clear effect on erosion. Dental plaque, induced by a powdered diet containing 15% sucrose, seemed to modify the erosion process by covering a part of the enamel and thus protecting these areas from the direct effect of acidic drink.