Restor Dent Endod.  2012 Mar;37(1):16-23. 10.5395/rde.2012.37.1.16.

Effect of fluoride concentration in pH 4.3 and pH 7.0 supersaturated solutions on the crystal growth of hydroxyapatite

• Shin H
• Park SH
• Park JW
• Lee CY

• KMID: 1995679
• DOI: http://doi.org/10.5395/rde.2012.37.1.16

Abstract

OBJECTIVES
Present study was undertaken to investigate the crystal growth onto synthetic hydroxyapatite (HA) seeds in pH 4.3 and pH 7.0 supersaturated solutions with different fluoride concentrations.
MATERIALS AND METHODS
8 groups of pH 4.3 and 7.0 calcium phosphate supersaturated solutions were prepared with different fluoride concentrations (0, 1, 2 and 4 ppm). Calcium phosphate precipitates yield crystal growth onto the HA seed surface while solutions flow. For evaluation of crystallizing process, the changes of Ca2+, PO4(3-), F- concentrations of the inlet and outlet solutions were determined. The recovered solid samples were weighed to assess the amount of minerals precipitated, and finally determined their composition to deduce characteristics of crystals.
RESULTS
During the seeded crystal growth, there were significantly more consumption of Ca2+, PO4(3-), F- in pH 4.3 solutions than pH 7.0 (p < 0.05). As fluoride concentration increased in pH 4.3 solution, Ca2+, PO4(3-), F- consumption in experimental solutions, weight increment of HA seed, and fluoride ratio in crystallized samples were increased. There were significant differences among the groups (p < 0.05). But in pH 7.0 solution, these phenomena were not significant. In pH 7.0 solutions, analyses of crystallized samples showed higher Ca/P ratio in higher fluoride concentration. There were significant differences among the groups (p < 0.05). But in pH 4.3 solution, there were not significant differences in Ca/P ratio.
CONCLUSIONS
Crystal growth in pH 4.3 solutions was superior to that in pH 7.0 solutions. In pH 4.3 solutions, crystal growth increased with showed in higher fluoride concentration up to 4 ppm.

Keyword

Fluoride concentration; Hydroxyapatite; pH; Seeded crystal growth

MeSH Terms

Bays
Calcium
Calcium Phosphates
Crystallization
Durapatite
Fluorides
Hydrogen-Ion Concentration
Minerals
Seeds
Calcium
Calcium Phosphates
Durapatite
Fluorides
Minerals

Figure

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  Figure 1 Schematic illustration of experimental set-up.

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  Figure 2 Schematic illustrations of calculating the amounts of crystal growth. (a) Amounts of seed crystals oriinally placed in the reaction column; (b) Weighed amounts of solid sampe recovered at the end of experiment; (b)-(a) Difference between (b) and (a), amounts of crystal growth.

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