Synthesis, mechanical and biological characterization of ionic doped carbonated hydroxyapatite/β-tricalcium phosphate mixtures

Simultaneous incorporation of magnesium and carbonate in apatite: effect on physico-chemical properties

“…A shift in the diffraction peaks (211 and 300) to a higher 2θ angle with increasing CO 3 2-content in the MCAp samples indicates decreasing a-axis dimensions. The contraction in the a-axis dimensions (compared to that of the magnesium-and carbonate-free apatites) can be attributed to the combined partial substitution of Mg group, when compared to that in the tetrahedral PO 4 3-group, and the substitution of smaller planar CO 3 2-groups for the larger tetrahedral PO 4 3-group, contribute to these effects on the lattice parameters 1,14 . Some authors related that the incorporation of Mg 2+ and CO 3 2-in the apatite lattice causes a reduction of crystal size, contraction in the a-axis dimension and expansion in the c-axis dimension, as well as increased solubility when compared to carbonate-free apatites 9,18,19 .…”

“…The decrease in the Ca and P concentration accomplished by the increase in the Na concentration are evidence for the CO 3 2--for-PO 4 3-, B-type substitution. The substitution of a trivalent anion, PO , facilitates the incorporation of a monovalent cation (Na + ) in the place of a divalent cation Ca 2+ to maintain the charge balance 1,5,14 . The source of the Na + ions could be the sodium carbonate and sodium phosphate reagents used in the reaction.…”

“…Two types of carbonate ion substitutions can occur in two distinct atomic sites in the apatite lattice, and have been described as A-or B-type 1 . The A-type substitution occurs when CO 3 2-substitutes for the hydroxyl (OH -) ions 12,13 , and the B-type substitution occurs when CO 3 2-substitutes for the phosphate (PO 4 3-) ions 1,14 . Depending on the application of the bone graft material, the in vitro solubility is one of the important parameters in the evaluation of their biodegradability and in vivo performance 3 .…”

Syntheses of Single-Crystal Apatite Particles with Preferred Orientation to the <i>a</i>- and <i>c</i>-Axes as Models of Hard Tissue and Their Applications

“…For example, in a living bone, the c-axes of HAp crystallites 50 nm×25 nm×4 nm in size are parallel to the extending collagen fibers, resulting in exposure of their a(b)-planes on the bone surface. [17][18][19][20][21][22] On the other hand, in dental enamel, HAp crystallites 100 µm×50 nm×50 nm in size form enamel prisms extending from the dentino-enamel junction, resulting in their c-planes being preferentially parallel to the enamel surface. [22][23][24][25][26] Moreover, the a(b)-plane and c-plane exhibit anisotropic characteristics, such as resolvability, biocompatibility, and absorptive activity.…”

“…[17][18][19][20][21][22] On the other hand, in dental enamel, HAp crystallites 100 µm×50 nm×50 nm in size form enamel prisms extending from the dentino-enamel junction, resulting in their c-planes being preferentially parallel to the enamel surface. [22][23][24][25][26] Moreover, the a(b)-plane and c-plane exhibit anisotropic characteristics, such as resolvability, biocompatibility, and absorptive activity. 2,10,11,[27][28][29] However, it is not clear why the orientations of living bone and dental enamel are in different crystal planes.…”