Effect Investigation of Ammonium Bicarbonate and Polyethylene Wax as Pore-Forming Agents on the Physicochemical Properties of Macroporous Biphasic Calcium Phosphate Bioceramics Processed by Space-Holder Technique

The effect of ammonium bicarbonate (AB) and polyethylene wax (PW) on the physicochemical properties of macroporous biphasic calcium phosphate bioceramics (BCPs) processed by space-holder technique was investigated. BCP powder was mixed with AB and PW and, then, uniaxially cold-pressed at 300 MPa. AB and PW were eliminated by heat treatment at 170 degrees C for 2 hours or 550 degrees C for 4 hours, respectively. Subsequently, the samples were air-sintered at 1070 degrees C for 2 hours. The results revealed that AB is more attractive than PW due to its lower degradation temperature, which has avoided the formation of undesirable phases. In addition, it favored an adequate consolidation of the particles with the formation of sintering necks that provided a better mechanical resistance to handling. The samples with AB also presented the formation of uniformly distributed macro and microporosity in great extension, which is shown by literature as a fundamental combination to stimulate cells/scaffold interaction.