Comparison study of porous calcium phosphate blocks prepared by piston and screw type extruders for bone scaffold

Abstract

Piston and screw type extruders were used to prepare calcium phosphate blocks comprising macro-pores interconnected with micro-pores for bone substitutes and scaffolds. First, dicalcium phosphate dehydrate (DCPD, CaHPO 4 ·2H 2 O), calcium nitrate tetrahydrate (CN, Ca(NO 3 ) 2 ·4H 2 O), hydroxyapatite (HAp, Ca 10 (PO 4 ) 6 (OH) 2 ), and polymer (poly-methyl methactrylate PMMA, (C 5 O 2 H 8 ) n ) beads were mixed with lubricants and a plasticizer to make a paste using a table mixer. The paste prepared for the screw extruder was thicker than that prepared for the piston extruder. The pastes were kneaded more than three times and then extruded. The extruded rods were dried at 100 o C for 24hrs and sintered at 1250 o C for 5hrs in the air. The porosity increased with increasing amount of DCPD and CN in both systems. The porosity of the piston extruded rod was higher than that of the screw extruder rod for the same raw material composition, except for the pure HAp porous bodies. In contrast to the porosity, the compressive strength was decreased upon the addition of DCPD and CN. The screw extruded specimens showed higher compressive strength than piston extruded ones. The macro-pores generated from the PMMA polymer beads were interconnected by micro-pores generated by the reaction of DCPD and CN, which existed in the strut. The SEM images clearly showed that the piston extruder generated more micro-pores than the screw extruder. The reaction of DCPD and CN affects the porosity, compressive strength and pore structure of the porous blocks. Also, the extruding method affects the pore characteristics.

Response of human bone marrow‐derived MSCs on triphasic Ca‐P substrate with various HA/TCP ratio

“…Furthermore, all green palettes were sintered at 1250°C at a heating rate of 5°C/min for 2 h in air. A similar composition was adopted by our research group to fabricate porous triphasic HA/TCP scaffolds . The experimental density of the sintered palettes was measured using the Archimedes method in double distilled water and the shrinkage was calculated by measuring the change in diameter after sintering.…”

Advanced bioactive and biodegradable ceramic biomaterials

“…Tricalcium and tetracalcium phosphates are higher temperature phases that, under physiological conditions, can be transformed into biological-type apatite (Bauer et al , 2013). Typically, scaffold constructs are fabricated using indirect rapid prototyping (Schumacher et al , 2010;Wilson et al , 2011;Xu et al , 2012), phase mixing (Dorozhkin, 2012;Kunjalukkal Padmanabhan et al , 2013;Lim et al , 2012;Lode et al , 2012), sintering (Deng et al , 2012;Schlosser and Kleebe, 2012), shape replication (Jokic et al , 2012;Sung et al , 2012;Tripathi and Basu, 2012), gas foaming (Chatterjee et al , 2012), salt leaching , freeze casting (Jafarkhani et al , 2012;Qi et al , 2012), to name but a few . Three-dimensional printing has also been investigated for fabrication of 3-D calcium phosphate scaffolds with tailored architecture and porosity at macro-and micro-scales (Butscher et al , 2012(Butscher et al , , 2013Lewis et al , 2006;Lode et al , 2012;Michna et al , 2005).…”

Fabrication, characterization and cellular biocompatibility of porous biphasic calcium phosphate bioceramic scaffolds with different pore sizes

“…Polymeric sponges, pore-making substances such as poly methyl methacrylate [12,27] or polystyrene beads [28], cane sugar [21], polyethylene glycol-polyvinyl alcohol hydrogel [10,29], and gas-foaming [30] have been reported. However, each method has its disadvantages and limitations.…”

“…One of the most significant challenges is to control the pore shape and size distribution of BCP bioceramic scaffolds. Large quantities of researches have shown attention on this, but they can only form scaffolds with a specific pore size [27][28][29][30]. To the best of our knowledge, there is no investigation that mainly focuses on the fabricating methods and cytological properties of porous BCP bioceramic scaffolds with different pore size distributions.…”