Microstructure and biocompatibility of composite biomaterials fabricated from titanium and tricalcium phosphate by spark plasma sintering

Abstract

Important issues in developing hydroxyapatite (HAp)- and titanium (Ti)-based composite biomaterials for orthopedic or dental devices include the dissociation of HAp during fabrication and its influences in the microstructure and biocompatibility of the final composite. During the densification by sintering of HAp/Ti composites, Ti reacts with -OH freed from HAp to form TiO2 thus dissociated HAp into Ca3(PO4)2, CaO, CaTiO3, TiP, and so forth. To inhibit this reaction, composites were fabricated with Ti and 30, 50, and 70 vol % β-tricalcium phosphate (β-TCP) instead of HAp by spark plasma sintering at 1200°C. It has been observed that after sintering at 1200°C, Ti also reacted with TCP, but unlike HAp/Ti composites, the final TCP/Ti composites contained significant amounts of unreacted TCP and Ti phases. The initial 70 vol % TCP/Ti composite showed compressive strength of 388.5 MPa, Young's modulus of 3.23 GPa, and Vickers hardness of 361.9 HV after sintering. The in vitro cytotoxicity and proliferation of osteoblast cells on the composites surfaces showed that the addition of a higher amount of TCP with Ti was beneficial by increasing cell viability, cell-composite attachment and proliferation. Osteopontin and collagen type II protein expression from osteoblasts cultured onto the 70% TCP-Ti composite was also higher than other composites and pure Ti. In vivo study verified that within 3 months of implantation in an animal body, 70% TCP-Ti had an excellent bone-implant interface compared with a pure Ti metal implant.

Hydroxyapatite‐titanium bulk composites for bone tissue engineering applications

“…Although PECS suppresses the oxidation of Ti at 900°C, the formation of Ti 2 O was found in samples sintered at 1000°C. Mondal et al used the SPS technique to sinter β‐TCP and Ti powders at 1200°C temperature under 50 MPa pressure. Despite the retention of β‐TCP and Ti, this results in the formation of CaTiO 3 .…”

Bioactivity of novel functionally structured titanium‐ceramic composites in contact with human osteoblasts

“…Hydroxyapatite (HA) and beta tricalcium phosphate (βTCP) are the most extensively studied calcium phosphates, and therefore, they are widely used in various applications, such as in biomaterials, ion exchangers, adsorbents, and catalysts . HA is also considered suitable for bone repairing, particularly in orthopedic implants to accelerate growth of surrounding bone because of the structural and chemical similarities between HA crystal and bone calcium phosphates.…”

“…Furthermore, bioactive ceramic materials can be used for Ti implant surface modification to stimulate migration and adhesion of cells and proteins, as well as to accelerate bone growth. Several methods have been used to coat Ti‐based implant surfaces with HA or TCP although the major concern is the prevalence of fractures at the Ti/ceramic interfaces by chipping on friction during implant placement into bone.…”

Chemical Stability of Tricalcium Phosphate–Iron Composite during Spark Plasma Sintering

“…This could be explained due to the thermal stability of the tricalcium phosphate ( Figure 1) and the less reactivity of iron in comparison with other metals like the titanium [15]. In fact, it has been reported that the spark plasma sintering of tricalcium phosphate-titanium powders has led to the partial degradation of the phosphate and the formation of CaTiO 3 phases [16]. For the TCP-Fe composite, no formation of CaO has been found as it is typical in the case of the hydroxyapatite-titanium composites.…”