Effect of various additives and temperature on some properties of an apatitic calcium phosphate cement

Abstract

The effect of additives and temperature on setting time, swelling time and compressive strength of a previously developed apatitic calcium phosphate cement was investigated. Setting was faster at body temperature than at room temperature. Early contact with aqueous solutions resembling blood and other body fluids had no effect. Deliberate additions of soluble carbonates, pyrophosphate or magnesium salts to the cement powder retarded or even inhibited setting. However, additions of calcium pyrophosphate, 13-tertiary calcium phosphate or sintered hydroxyapatite to the cement powder in amounts up to 10% had no effect on the cement properties. Several organic substances were used as additives. They all retarded the setting and decreased the strength of the cement considerably.

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

“…For example, water demand of calcium orthophosphate cements can be reduced by ionically modifying the liquid component, e.g., by adding nontoxic sodium salts of α-hydroxy di-and tri-acids [281,282]. A list of additives, that have been already studied, includes fluidificants, air-entraining agents, porogens, workability-improvement agents, setting time controllers and reinforcing additives [162,203,283]. Besides, various radiopacifiers might be used to simplify an un-invasive in vivo monitoring of the implanted cements [284][285][286][287].…”

Effects of silica addition on the chemical, mechanical and biological properties of a new α-Tricalcium Phosphate/Tricalcium Silicate Cement

“…One of the most important formulations is based on a-tricalcium phosphate [a-Ca 3 (PO 4 ) 2 ; a-TCP], which sets in situ and forms a calcium-deficient hydroxyapatite [Ca 9 (HPO 4 )(PO 4 ) 5 (OH); CDHA] when hydrated 3 . However, it is not very strong under compression 4 and its mechanical strength is low when compared to that of cortical bone 5 , limiting its application to areas subjected to low mechanical loads 6 . In view of the excellent bioresorbability of CDHA, researchers have focused their efforts on overcoming the mechanical weakness of calcium phosphate cements by using different fillers, fibers and reinforcing additives that lead to the formation of various multiphase composites, based on the idea that the filler in the matrix may eliminate crack propagation 7 .…”

Bioactive composite bone cement based on α‐tricalcium phosphate/tricalcium silicate

“…The liquid phase was a sodium phosphate buffer prepared from NaH 2 PO 4 and Na 2 H-PO 4 .12H 2 O, and the liquid/powder ratios (L/P) was dependent of the content of C 3 S added ranging from 0.4 to 0.44 mL/g. Each powder sample was carefully weighed and mixed with the liquid phase in appropriate liquid-to-powder ratio, packed into silicon molds and aged at 36.5 C with controlled humidity for 24 h.…”

“…2 One of the most important formulations is that based on a-tricalcium phosphate [a-Ca 3 (PO 4 ) 2 ; a-TCP] which sets in situ and forms a calcium deficient hydroxyapatite [Ca 9 (H-PO 4 )(PO 4 ) 5 (OH); CDHA] when hydrated. 3 However, it is only strong enough under compression 4 and has low mechanical strength when compared with cortical bone 5 ; consequently, its application is restricted to places that require low mechanical loads. 6 Being aware of the excellent bioresorbability of CDHA, researchers are concentrating their efforts in trying to overcome the mechanical weakness of calcium phosphates cements by using different fillers, fibers, and reinforcing additives that lead to the formation of various multiphase composites based on the idea that a filler in the matrix might stop crack propagation.…”