The Formation of Hydroxyapatite-Ionomer Cements at 38°C

Abstract

This study describes the formation of a calcium polyacrylate-hydroxyapatite cement. Our hypothesis was that calcium phosphates would rapidly hydrolyze in the presence of polyacrylic acid (PAA) to form a cement. PAA, tetracalcium phosphate (TetCP), and dicalcium phosphate (DCP) were reacted together and formed calcium polyacrylate (CPA) and hydroxyapatite(HAp) within 10 h at 38 degrees C, resulting in hardened masses. Reaction times increased with decreasing (HApreactants)/PAA ratios. In the first of three reaction stages, the pH increased while CPA and dicalcium phosphate dihydrate (DCPD) formed. Two steady-state pH conditions occurred during the second stage as TetCP reacted with DCPD and DCP. The first steady-state pH was the result of DCPD and TetCP reacting at near-equilibrium conditions. The second steady-state pH resulted as the reaction became limited by DCP dissolution. The third, diffusionally controlled, stage occurred as DCP and previously formed HA preacted to produce calcium-deficient HAp (Ca/P = 1.5). The emphasis of this investigation was to establish the mechanistic path involved and the rate-limiting steps of the reaction.

Tetracalcium phosphate: Synthesis, properties and biomedical applications

“…The first type is based on modification with (water-soluble) non-reactive polymers, such as hydroxypropylmethylcellulose [60] or chitosan [61]. In a second type of cements, the high reactivity and strong basic character of TTCP compared with other calcium phosphates is used to react with carboxylic acid or organic phosphate moieties of the polymer, such as polyacrylic acid [62][63][64], poly(methyl vinyl ether-maleic acid) [10,65], poly[bis(carboxylatophenoxy)phosphazene] [66], poly(vinyl phosphonate) [67][68][69] (Fig. 1).…”

Self-Setting Calcium Orthophosphate Formulations: Cements, Concretes, Pastes and Putties

“…However, further investigations have shown that only the first nuclei consist of a nearly stoichiometric HA, whereas further growth of these nuclei occurs in the form of CDHA [145]. Besides, there is a study demonstrating that the initially formed stoichiometric HA further interacts with remaining DCPD to form CDHA [146].…”

Preparation, characterization, and in vitro release of gentamicin from coralline hydroxyapatite‐alginate composite microspheres

“…Recently, composites of ceramics with natural degrad-able polymers are attracted much interest as a bone filler. 16 -18 Several particle composites based on degradable biopolymers such as collagen, 19 fibrin glue, 20 starch-based material, 21 gelatin, 22,23 chitosan, 24,25 alginate, 26,27 and hydroxy-propyl-methyl cellulose 28 with inorganic powders, as bone filler were developed. 29 Recently, a mixture of HA powder (or HAP) and saline solution of sodium alginate was prepared by Maruyama et al 30 -32 This mixture was named HAP clay and showed excellent osteoconductive properties, bridging the gap between implants and cortical bone without any adverse reaction.…”