Page 390 - Biomedical Engineering and Design Handbook Volume 1, Fundamentals

BIOCERAMICS 367

A
OH
O
Ca(I)
Ca(II)
P

B
OH
O
Ca(I)
Ca(II)
P

FIGURE 15.5 Schematic of hydroxyapatite crystal structure: (a) hexagonal, (b) monoclinic. [From Kohn
and Ducheyne (1992), with permission.]

TABLE 15.3 Calcium-Phosphate Phases with Corresponding Ca/P Ratios
Name Formula Ca/P Ratio
Hydroxyapatite (HA) Ca (PO ) (OH) 1.67
10 4 6 2
Fluorapatite Ca (PO ) F 1.67
10 4 6 2
Chlorapatite Ca (PO ) Cl 1.67
10 4 6 2
A-type carbonated apatite (unhydroxylated) Ca (PO ) CO 1.67
10 4 6 3
B-type carbonated hydroxyapatite (dahllite) Ca [(PO ) (CO ) ](OH) ≥1.67
10-x 4 6-2x 3 2x 2
Mixed A- and B-type carbonated apatites Ca [(PO ) (CO ) ]CO ≥1.67
10-x 4 6-2x 3 2x 3
HPO containing apatite Ca [(PO ) (HPO ) ](OH) ≤1.67
4 10-x 4 6-x 4 x 2-x
Monohydrate calcium phosphate (MCPH) Ca(H PO ) H O 0.50
2 4 2 2
Monocalcium phosphate (MCP) Ca(H PO ) 0.50
2 4 2
.
Dicalcium phosphate dihydrate (DCPD) Ca(HPO ) 2H O 1.00
4 2
Tricalcium phosphate (TCP) α and β-Ca (PO ) 1.50
3 4 2
.
Octacalcium phosphate (OCP) Ca H(PO ) 5H O 1.33
8 4 6 2
Source: Adopted from Segvich et al. (2008c), with permission.