Prevention by means of fluoride of enamel erosion as caused by soft drinks and orange juice.

Fluoride has been suggested to prevent erosion of the teeth, either after a topical treatment of the teeth or by addition of fluoride to the acidic drink. The main aim of the present study was to describe the dissolution of calcium fluoride in some soft drinks and orange juice and compare it with the amounts of calcium fluoride left on the enamel surfaces after a topical treatment. A further aim was to describe the dissolution of enamel in soft drinks and juice saturated for 3 days with solid calcium fluoride. Solid calcium fluoride was suspended in each of 10 soft drinks and orange juices and gently agitated for 72 h, after which the drinks were analyzed for calcium, phosphate and fluoride and pH was determined. To examine the erosion-preventive effect of the calcium fluoride-rich drink, intact teeth were exposed to the drinks with or without calcium fluoride. It was found that from 6 to 45 mg of calcium fluoride was dissolved per liter of drink. The more acidic the drink, the more calcium fluoride was dissolved, presumably due to HF formation. The teeth exposed to the soft drinks all showed erosion-like lesions. Very little effect of the 4-6 ppm ionic fluoride dissolved in the soft drinks was observed. In orange juice, however, the dissolved calcium fluoride established a saturation with respect to fluorapatite and consequently, the erosion-like lesion was replaced by a caries-like lesion. In conclusion, the acidic soft drinks are capable of dissolving considerable amounts of calcium fluoride and the erosion-preventive effect of even high fluoride concentrations is limited.