Stoichiometry and Thermodynamic Solubility Properties of Dentin Mineral of Human Permanent and Deciduous Teeth.

Abstract

Abstract:Acquisition of substantial amounts of CO32-, HPO42-and other impurities is universally encountered in bioapatites from mammals. To date, however, there is a paucity of information about the stoichiometry and, on that basis, solubility product of dentin mineral. In this report, we summarize our experimental approach toward the determination of the stoichiometry model and thermodynamic solubility products of human dentin apatites. Dentin samples were collected separately from the coronal portion of permanent premolars (extracted for orthodontic reasons) and exfoliated deciduous teeth. Both pooled organic matter. The stoichiometry model selected for these crystals was (Ca)5 -x (Mg)q (Na)u (HPO4)v (CO3)w (PO4)3-y (OH)1-z. These stoichiometric coefficients were analytically determined by assessing separately the labile or surface pools of the ionic species on the crystal surface and their stable pools in the bulk for a maximum of 28 days under constant partial pressures of CO2 . The results showed that there are appreciable differences in the crystal stoichiometry between the permanent and deciduous dentin mineral deciduous dentin, which were determined under 1 .8% CO2/N2. Notably, the solubility properties of the dentin mineral remained relatively constant in the range of 1 .0 through 3.3% CO2/N2, whereas the discrete solubility data were obtained below and above the corresponding partial pressure of CO2 .

Solubility properties of human tooth mineral and pathogenesis of dental caries

“…(Ca) 5·x (Mg) q (Na) u (HPO 4 ) v (CO 3 ) w (PO 4 ) 3·y (OH,F) 1·z (Aoba, 1997). The stoichiometric coefficients for each mineral were determined in combination with analytical procedures to distinguish the fraction of the ions in the bulk crystals from the pools of the corresponding ions on the crystal surfaces (Aoba et al , 1992a,b; Komatsu et al , 2001). The information obtained so far is given in Table 1, although the estimates for coefficients still involve gross approximations that should be refined.…”

“…In order to avoid such incongruent equilibration, we initiated solubility measurements of enamel and dentin apatites in the system Ca(OH) 2 ‐CO 2 ‐H 3 PO 4 ‐H 2 O (Moreno and Aoba, 1991; Aoba and Moreno, 1992; Komatsu et al , 2001). In solubility experiments, the equilibration of each of the pulverized samples was conducted with dilute phosphoric acid solutions and CO 2 /N 2 atmospheres at 25°C.…”