Calcium‐deficient apatite: A first in vivo study concerning bone ingrowth

Abstract

Biphasic calcium phosphate (BCP) materials are increasingly used to restore bone loss in surgery. Calcium-deficient apatites (CDA), the precursors of BCP, are closer in structure to biological apatites and can be associated with therapeutic agents to form drug-delivery systems. The purpose of this first in vivo study of CDA was to evaluate the osteoconductive properties of two composites, consisting of 40-80 microm granules carried by a cellulose-derived polymer, used to fill critical size bone defects in rabbit femoral ends. Animals were sacrificed 2 or 3 weeks after implantation. Histomorphometric analysis of scanning electron microscopy implant surface files was performed using gray level threshold that distinguish between bone or materials (white) and noncalcified tissue (black). Quantitative results for new bone formation showed no significant differences between the composites or the implantation periods. However, nearly all of the CDA disappeared early while supporting more extensive bone colonization than biphasic calcium phosphates implanted in the same conditions.

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Theoretical investigations of the defect formation mechanism relevant to non-stoichiometry in CDHA are available elsewhere (Matsunaga 2008b Rey et al 2006;O'Neill 2007). Therefore, CDHA is a very promising compound for industrial manufacturing of artificial bone substitutes (Bourgeois et al 2003), including drug delivery applications (Liu et al 2005). Non-biomedical applications of CDHA are similar to those of ACP and HA.…”

Bone-like Layer Growth and Adhesion of Osteoblast-like Cells on Calcium-deficient Hydroxyapatite Synthesized at Different pH

“…So, one can say that the potential of DAp as a bone substitute is higher than that of stoichiometric HAp. 5) Moreover, DAp was reported to dissolve in vivo earlier than HAp. The formation process of new bones in vivo consists of adhesion of osteoblast cells and mineralization.…”

Self-Setting Calcium Orthophosphate Formulations

“…The implanted calcium orthophosphates might be bioresorbed by two possible mechanisms, namely: an active resorption, mediated by the cellular activity of macrophages, osteoclasts and other types of living cells (so called phagocytosis or literally -cell-eating‖) [419][420][421] and a passive resorption due to either dissolution [6] or chemical hydrolysis (brushite-forming formulations only) [180,259] in the body fluids. Dissolution might be both chemical and physical.…”