Chan, Fluoride Stability in Dicalcium Phosphate Dihydrate
Composition, in, US, Patent No.
Nancollas, The Crystallization of Hydroxyapatite and Dicalcium Phosphate Dihydrate
; Representation of Growth Curves, .J.
It shows moderate reactivity and solubility when combined with acidic calcium phosphates such as dicalcium phosphate anhydrous (CaHP[O.sub.4], DCPA, monetite) or dicalcium phosphate dihydrate
(CaHP[O.sub.4] * 2[H.sub.2]O, DCPD, brushite).
Since their first development in the 1980's, calcium phosphate cements (CPC) have attracted considerable attention because these materials set like cements and form nanocrystalline hydroxyapatite (HA) (1) or microcrystalline dicalcium phosphate dihydrate
(DCPD) (2) as the major product.
The other type is based on acid-base reaction of tetracalcium phosphate [([Ca.sub.4]O(P[O.sub.4]).sub.2]; TTCP) and acidic dicalcium phosphate dihydrate
(CaHP[O.sub.4] 2[H.sub.2]O; DCPD) put forward by Brown and Chow .
Dicalcium phosphate anhydrous (DCPA) and dicalcium phosphate dihydrate
(DCPD) (5), octacalcium phosphate (OCP) (6) and other calcium phosphate compounds (5), (7-9) are used either as components or formed as products of calcium phosphate bone cements.
CPCs of different compositions can form different end products such as hydroxyapatite (HA), octacalcium phosphate, and dicalcium phosphate dihydrate
(DCPD), also known as brushite.
In fact, preliminary data indicated that no residual acid was present in dicalcium phosphate dihydrate
nano particles prepared by this process.
Based on the solubility properties of calcium phosphates (1), they formulated mixtures containing tetracalcium phosphate (TTCP), [Ca.sub.4][([PO.sub.4]).sub.2]O, and dicalcium phosphate anhydrous (DCPA), [CaHPO.sub.4], or TTCP and dicalcium phosphate dihydrate
. When mixed with water these mixtures would rapidly form hydroxyapatite (HA), [Ca.sub.5][([PO.sub.4]).sub.3]OH, which is the major component of tooth mineral, at body temperatures.
Dicalcium phosphate dihydrate
(DCPD), Ca[HPO.sub.4]*2[H.sub.2]O, occurs as the mineral brushite and crystallizes in the monocinic space group Ia with unit cell parameters a = 5.812(2) [Angstrom], b = 15.180(3) [Angstrom], c = 6.239(2) [Angstrom] and [beta] = 116.42(3)[degrees], Z = 4 (41).