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Journal of Dental Research

The Effect of Topical Fluoride Applications on the Surface Free Energy of Human Enamel- An in vitro Study
H.P. De Jong, A.W.J. Van Pelt, H.J. Busscher and J. Arends J DENT RES 1984 63: 635 DOI: 10.1177/00220345840630050501 The online version of this article can be found at:

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The Effect of Topical Fluoride Applications Surface Free Energy of Human Enamel An in vitro Study



H. P. de JONG, A. W. J. van PELT, H. J. BUSSCHER, and J. ARENDS
Dental School, State University ofGroningen, Ant. Deusinglaan 1, 9713 A V Groningen, The Netherlands

human enamel treated with sodium fluoride, acidulated phosphate fluoride (APF), and aminfluoride solutions. Sodium fluoride solutions only slightly influenced the surface free energy component ysP. The y5P value of the APF-treated human enamel increased from 52 to 66 The -ysP value after aminfluoride treatment decreasedfrom 52 to 19 The ysd values remained about 35 for all specimens measured. It is suggested that aminfluoride-treated enamel surfaces may exhibit a reduced tendency for bacterial adhesion.

7ysP and 5ysd were determined from contact angle measurements on

The surface free energy ys and its polar and dispersion components

Materials and methods.
Enamel specimen preparation.- Extracted human anterior teeth were used for all experiments. The buccal surfaces of the teeth were cut into pieces of 3 x 3 mm2 and subsequently embedded horizontally in polymethylmethacrylate. Care was taken to prevent contamination of the enamel surface with acrylic. The specimens were ground on silicon carbide paper (1200 grit) under running tap water and polished with a slurry of A12 03powder* (particle diameter 0.05 ,um) in distilled water, in order to obtain flat enamel surfaces, free of the superficial fluoride-rich layer. This results in the removal of about 60 ,um from the anatomical tooth surface, as measured with a Sony digital gauging probe type D.G.-3 10 and magnescale LY-101. After being ultrasonically cleaned and dried in an incubator at 370C (both for ten min each), theenamel specimens were fluoridated by solutions of neutral sodium fluoride (0.2% F , pH 7), acidulated phosphate fluoride (0.2% F , 0.1 M H3PO4, pH _ 4), and aminfluoridet (1% F, pH 4) for one, three, five, and ten min. To remove excess fluoride, all enamel slabs were rinsed with distilled water for approximately one min. In a separate experiment, the specimens were treated with aminfluoride forten min, and rinsed twice for two min. Contact angle measurements and surface free energy determinations. - The contact angle measurements were done by the sessile drop technique, which has been described previously (De Jong et al., 1982a). All angles reported are of the advancing type. The wetting liquids and their reference states are given in Table 1. The surface free energies were calculatedaccording to the so-called polar and dispersion surface free energy concept (Busscher et al., 1 983a), whereby the following relations have been used:

J Dent Res 63(5):635-641, May 1984

There is no doubt in dentistry concerning the preventive value of fluoride. Fluorides reduce the progression of caries lesions in human enamel (Gron, 1977; Caslavska et al., 1971; Koch and...
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