Porous spherical hydroxyapatite and fluorhydroxyapatite granules: processing and characterization

Abstract

This study is aimed at the development of a method to fabricate porous spherical hydroxyapatite (HA)-fluorapatite (FA) granules. The method to produce porous granules is based on liquid immiscibility effect. A suspension of HA -FA powder mixtures in aqueous solution of gelatin and oil as a dispersion media were used. By stirring the mixtures of these immiscible liquids, granules of 50 -200 mm diameter can easily be produced. The granules were characterized with respect to their microstructure, phase composition and specific area. In vitro testing of human plasma protein adsorption onto the granules of HA and fluorhydroxyapatite were performed. No kind of difference in the dynamic protein adsorption between pure HA and the HA up to 10 wt% FA materials has been revealed. q

Optimizing the Water-Oil Emulsification Process for Developing CPC Microspheres

“…has compared two powders, one coarse with d(50) of 10.88 µm and one fine with d(50) of 2.22 a significant variable to the sphericity of the microspheres (Figure 5), however when was P/O ratio of 0.02 with a L/P ratio of 0.5, has improved the sphericity of the microspheres and the benefit that the amount of oil was reduced leading to a cost reduce of the process and it will produce less waste material, this is an advantage comparing with the emulsion made by Perez et al 1 , that has fixed the cement paste-to-oil ratio in 0.01. However, this amount of oil cannot be very small in order to avoid the inversion of phases W/O to O/W, which would lead to formation of scaffolds instead of microspheres 11,14 . The microspheres obtained have sizes between 6.29 and 64.23 µm as shown in the graph of Figure 3 and in the micrographs ( Figure 6).…”

“…Commonly, the production of ceramic microspheres requires two steps: (i) microspheres consolidation and; (ii) microspheres stabilization which can be achieved by sintering or processes that involves gellification or crosslinking of organic phases 1 . Nevertheless, these processes are low yield, difficult in controlling the granules shape and, in addition, some processes use toxic substances such as, paraffin 9,6,11 . One way of produce ceramic microspheres without the need of a subsequent sinterization step would be by the formation of water/oil emulsions (W / O) in which calcium phosphate cements are the hydrophilic phase and a vegetable oil the lipophilic phase.…”

Synthetic and Marine-Derived Porous Bone Graft Substitutes

“…It is involved in the prevention and treatment of dental caries. The incorporation of F -ions into the HA structure stimulates the osteoblast proliferation and differentiation and improves the mineral deposition in cancellous bone [203][204][205]. Two different levels of F -substitutions (46% and 85%) on the OH -sites via HT at 200°C for 24 h were studied by Kannan et al [201].…”

Fracture safety of double-porous hydroxyapatite biomaterials

“…A corresponding, particularly successful clinical example concerns filling of mandibular defects with double-porous hydroxyapatite granules that promote cell migration and tissue growth within the defect, eventually filling the latter. [1][2][3] The aforementioned scaffolds provide not only sufficient pore space for cell migration and angiogenesis (both anticipating bone tissue production) but also remarkable stiffness and strength, since they undergo repeated mechanical loading in the course of normal physiological use of the mandible. Hence, understanding of their mechanical function is of great interest, and their elasticity properties have been investigated in recent theoretical-computational campaigns, 4,5 revealing that 'macrocracks' of the order of tens of micrometers are essential for tuning the scaffolds' overall stiffness properties close to those of natural bone tissue and suggesting biomaterial resorption and bone apposition rates needed for maintaining the stiffness of the constructs consisting of tissue engineering scaffolds and bone tissue.…”