Observations on the Apparent Solubility of Carbonate–Apatites

Uptake of Fluoride from Aqueous Solution on Nano-Sized Hydroxyapatite: Examination of a Fluoridated Surface Layer

“…Carbonate is known to substitute into HAP, and this has been found to be associated with release of PO 4 and decreased stability of the HAP crystal structure. 43 Although this would be expected to decrease F − uptake, no such effect was observed in this study.…”

The Early Stages of Native Enamel Dissolution Studied with Atomic Force Microscopy

“…It has been shown that 4-5 wt% carbonate can double the dissolution rate of apatite (8) mainly due to an increased microstrain in the crystals with the incorporation of carbonate (9). The reduction in negative charge caused by substitution of CO 2− 3 for PO 3− 4 ions is for example compensated by replacement of Ca 2+ by Na + where the latter is present (10). During this reaction, carbonated hyroxyapatite dissociates to calcium, phosphate, carbonate and hydroxide ions, while carbonated fluoroapatite sets calcium, phosphate, carbonate, and fluoride ions free.…”

“…Inorganic phosphorus is found in nature mainly in calcium apatite either as fluorapatite [Ca 10 (PO 4 ) 6 F 2 ] or hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] (1). In particular, hydroxyapatite is the principal inorganic constituent of bones and teeth.…”

Influence of crystallite microstrain on surface complexes governing the metastable equilibrium solubility behavior of carbonated apatites

“…Within the time scale of laboratory experiments, CAPs do not follow conventional solubility theory (i.e., the thermodynamic solubility product principle) but exhibit a behavior termed "metastable equilibrium solubility (MES)" [12,13]. All apatite preparations investigated to date appear to demonstrate the MES and the MES distribution phenomenon [8,[12][13][14][15][16][19][20][21][22][23][24][25] including CAPs synthesized at various temperatures, possessing different carbonate levels and crystallinities, bone mineral from rats of different ages, and human dental enamel. Recent work has established that, for a given CAP preparation, a relationship may exist between the MES (and the MES distribution) and a MES driving force, which may be expressed in terms of a relevant ion activity product, K MES .…”

“…Carbonated apatites (CAPs) have been widely investigated because they have been considered to be excellent models for studying the physicochemical properties of biological hard tissues [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. From the physical chemical standpoint, CAPs closely parallel biominerals (e.g., dental enamel and bone mineral) in terms of dissolution [2,5], structure [1,6,17,18], thermal treatment [11], and solubility behavior [12,19].…”