The biodegradation mechanism of calcium phosphate biomaterials in bone

Abstract

This study was undertaken to understand the biodegradation mechanisms of calcium phosphate (Ca-P) biomaterials with different crystallization. Two types of sintered Ca-P porous ceramic (HA and beta-TCP) and a Ca-P bone cement (CPC) were implanted into cavities drilled in rabbit femoral and tibiae condyles. The results have shown that a material biodegradation was rapid in the beta-TCP and the CPC, but very weak in the HA. This biodegradation presented a decrease of material volume from the periphery to the center as well as a particle formation causing phagocytosis by numerous macrophages and multinucleated giant cells in the CPC. In the beta-TCP, there was a peripheral and central decrease of material volume as well as an absence of particle formation or visible phagocytosis. The process of biodegradation is considered to be directly influenced by the type of material crystallization. The sintered bioceramics processed at a high temperature exhibit good crystallization and are primarily degraded by a process dependent on interstitial liquids. However, the bone cement is formed by physicochemical crystallization and is degraded through a dissolution process associated with a cellular process.

Periodontal repair following implantation of beta-tricalcium phosphate with different pore structures in class III furcation defects in dogs

“…However, the porosity of the tunnel-pipe β-TCP (72%) was greater than that of continuous porous β-TCP (60%). These results confi rmed the fi ndings of previous reports which demonstrated that high porosity promoted greater bone formation [31][32] . The volume of implanted β-TCP remaining within the furcation in the T group was less than that in the CP group, which could explain the difference in the porosity of the implanted material.…”

Small-sized granules of biphasic bone substitutes support fast implant bed vascularization

“…[8][9][10][11][12][13] Granule size is also believed to have a major influence on the successful application of bone substitute materials, as it is supposed to regulate the degradability of bone substitutes. 8 However, until now no consensus has been found concerning this material factor.…”

“…8 Material factors such as the porosity, surface structure and shape of the material granules have been identified as determining factors in material-mediated bone growth and degradation. [8][9][10][11][12][13][14] Among these properties the granule size of the bone substitute material is also assumed to exert a large influence on its regenerative potential, as it is expected to govern the material resorbability. 8 A variety of in vitro and in vivo studies have been conducted to quantify the impact of this factor on the progress and outcome of bone regeneration, but no definitive conclusions have thus far been reached.…”

Small‐animal models for testing macroporous ceramic bone substitutes

“…Different animal species have also been used to evaluate bone substitutes. For instance, in vivo studies have been conducted in rats, 10,15,20 rabbits, 8,16,[21][22][23][24][25] dogs, 13,26,27 sheep, 9 and goats. 28 As these animals are different in terms of their metabolisms and bone physiology, direct and strict comparison between all these studies is difficult.…”