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Effect of Tooth-Bound Fluoride on Enamel Demineralization/Remineralization in Vitro



Shozo Takagi, N S. Liao, Laurence C. Chow


The effect of tooth-bound fluoride (F) on enamel caries formation was investigated under the condition that loosely-bound F was essentially absent. Eighteen thin enamel sections, prepared from the lingual or buccal surfaces of extracted human molars, were imbedded in acrylic resin with the enamel surfaces exposed. The sections were placed in a pH 7 remineralizing solution (RS) (1.2 mmol/L Ca, 0.72 mmol/L PO 30 mmol/L KCl, 50 mmol/L HEPES) for 5 days, and were randomly divided into 3 groups: (1) control group that received no treatment, (2) acidulated phosphate fluoride (APF) group that received 5 cycles of a 4 min treatment with APF gel followed by immersion in the RS for 2 days (RS changed daily), and (3) dicalcium phosphate dihydrate (DCPD) -APF group that received 5 cycles of a 4-min pH 2.1 DCPD-forming solution followed by 4-min APF gel and then placed in the RS for 2 days. After the treatment cycles, the sections were washed in a constant composition F titration system to remove loosely-bound F. An in vitro model, which consisted of cycles of de- (6 h) and re-mineralization (18 h) each day for 5 days, was used to produce caries-like lesions in the specimens. The {Δ}Z (mineral loss) values, measured by quantitative microradiography, of the lesions formed in the three groups were (mean standard deviation; n = 6) 91.2 12.3 m for the control group, 41.3 10.1 m for the APF group and 21.2 4.8 m, for the DCPD-APF group. The same system produced lesions in untreated shark enamel with a mean δZ of 4.4 0.3 m (n=12). One-way fixed effects ANOVA indicated that mineral loss was significantly different among the different groups (p
Caries Research


acidulated phosphate fluoride, dicalcium phosphate dihydrate, fluorapatite, human enamel, pH cyclic model, tooth-bound fluoride


Takagi, S. , Liao, N. and Chow, L. (1999), Effect of Tooth-Bound Fluoride on Enamel Demineralization/Remineralization in Vitro, Caries Research (Accessed May 29, 2024)


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Created May 1, 1999, Updated February 17, 2017