Fabrication of bioresorbable hydroxyapatite bone grafts through the setting reaction of calcium phosphate cement

Abstract

We prepared hydroxyapatite (HAp) bone grafts by the setting reaction of calcium phosphate cement, and investigated the effects of the porosity and crystallinity on the osteoconductivity and bioresorbability. We examined the effect of the water-mixing ratio, pressure, and post-heat treatment temperature during preparation on the crystallite size and porosity of the HAp blocks. The quantity of protein adsorption increased with increasing porosity and specific surface area (SSA) of the HAp blocks, whereas the initial cell attachment was similar despite the different porosities and crystallinities. In in vitro dissolution tests with a pH 5.5 buffer, which mimics an osteoclast-created Howship's lacuna, both the porosity and SSA of the HAp blocks affected the solubility; most likely due to the increased contact area with the buffer. Thus, HAp blocks prepared by the setting reaction of calcium phosphate cement could be applicable for bioresorbable HAp bone grafts because of the high porosity and SSA.

Calcium Phosphate Cements as Carriers of Functional Substances for the Treatment of Bone Tissue

“…Calcium phosphate blocks and granules obtained as a result of the hardening of calcium phosphate cement are a promising type of scaffold for restoring bone defects due to their similarity in composition with the mineral component of bone tissue, high specific surface area, and increased resorption rate compared to matrices obtained by high-temperature processing. In addition, the volumetric incorporation of functional substances at the stage of mixing the components can be used to change the release kinetics, in contrast to the surface impregnation of high-temperature calcium phosphate materials [117,[125][126][127][128]. Matrixes can be formed by casting cement paste into molds, by interacting pre-pressed initial components in an aqueous medium via setting and hardening, and by 3D printing; they can serve as a substrate in tissue engineering and are an excellent platform for incorporating functional substances [117,[129][130][131].…”

“…Powders and blocks of cements can be sterilized by γ-irradiation without the loss of biocompatibility and bioactivity [134]. Steam sterilization, ethanol sterilization, and ethylene oxide sterilization with complete degassing after sterilization are also mentioned [128,131,135]. Gamma radiation for powder components and filtration for liquid components are used in the sterilization of cement formulations [136].…”

Physicochemical Properties of Inorganic and Hybrid Hydroxyapatite-Based Granules Modified with Citric Acid or Polyethylene Glycol

“…The search for biocompatible and bioactive materials has led researchers to explore the potential of calcium phosphate cements (CPCs) [1,2]. These remarkable biomaterials have garnered significant interest in recent years due to their unique properties, such as mouldability and setting in situ, diverse applications, and exceptional biocompatibility in various biomedical fields [3].…”