Self-Setting Calcium Orthophosphate Formulations

Abstract

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided.

Calcium Phosphate/Etidronate Disodium Biocement: Etidronate, Retarder or Accelerator

“…The first transformation of this paste is after mixing with an aqueous phase and right before placing it into a defect [8]. This is known as the initial setting (hardening).…”

Effects of powder-to-liquid ratio on properties of β-tricalcium-phosphate cements modified using high-energy ball-milling

“…A effective approach to improving the injectability is to reduce the powder-to-liquid ratio (P/L ratio) of the CPC 8) . However, doing so adversely affects the mechanical properties of a CPC after setting, while simultaneously increasing the setting time 3,9) . An effective approach to improve the injectability is decreasing the particle size of CPC powder 3) .…”

“…However, doing so adversely affects the mechanical properties of a CPC after setting, while simultaneously increasing the setting time 3,9) . An effective approach to improve the injectability is decreasing the particle size of CPC powder 3) . One popular process to reduce the size is mechanical milling process.…”

“…The modified β-TCP cement had an extremely high level of injectability, suggesting that the injectability would be sufficient despite the value falling as the P/L ratio increases. In addition, cements mixed with a higher P/L ratio should simultaneously exhibit a shorter setting time and higher strength 3,9,13) .…”

“…Calcium-phosphate-cements (CPCs) are widely used for bone repair and bone augmentation [1][2][3][4] . However, one of the problems with currently available commercial CPCs is their poor injectability 5,6) .…”