Effects of pore size and porosity of surface-modified porous titanium implants on bone tissue ingrowth

The effects of surface-modified porous titanium implants with different porosities and pore sizes on osseointegration were investigated in vivo.Three porous titanium implants(A30,A40 and A50 containing volume fractions of space-holder NaCl being 30%,40%and 50%,respectively)were manufactured by metal injection moulding(MIM).The surface-modified implants were implanted into muscles and femurs of hybrid male dogs.Interface osteogenic activity and histological bone ingrowth of porous titanium implants were evaluated at 28,56 and 84 d.The results showed that when additive space-holder amount of NaCl increased from 30%to 50%(volume fraction),the general porosity and mass fraction of macropores of porous titanium rose from 42.4%to 62.0%and from 8.3%to 69.3%,respectively.Histologic sections and fluorescent labeling showed that the A50 implant demonstrated a significantly higher osteogenic capacity at 28 d than other implants.Bone ingrowth into the A30 implant was lower than that into other implants at 84 d.Therefore,the pore structure of A50 implant was suitable for new bone tissue to grow into porous implant.

Bone integration properties of antibacterial biomimetic porous titanium implants

A novel antibacterial biomimetic porous titanium implant with good osseointegration was prepared by freeze-casting and thermal oxidation.Bone integration properties of the porous titanium implant were evaluated by cell proliferation assay,alkaline phosphatase activity assay,X-ray examination and hard bone tissue biopsy.The in vitro cell proliferation and the level of differentiation of the group with a modified nano-porous implant surface were significantly higher than those in the group without surface modification and the dense titanium control group(P<0.05).In vivo,bone growth and osteogenesis were found in the experimental groups with modified and unmodified porous titanium implants;osteoblasts in the modified group had more mature differentiation in the pores compared to the unmodified group.Such implants can form solid,biologically compatible bone grafts with bone tissues,exhibiting good osseointegration.

Evaluation of channel-like porous-structured titanium in mechanical properties and osseointegration

The porous titanium with a channel-like pore structure fabricated by infiltration casting followed by selectively dissolving the precursor woven three dimensional(3D)structure technique was comprehensively investigated by means of mechanical tests,in vitro and in vivo evaluation.Such porous structure exhibited superiority in compressive,tensile strength and osseointegration.At 40%porosity,the average compressive and tensile strength reached about 145MPa and 85 MPa,which was superior to that of other porous titanium,e.g.,Selective Laser Melting or powder sintered ones,and was comparable to that of the human cortical bone.Without any bioactive surface treatment,this porous titanium exhibited good cell adhesion,rapid cell proliferation and excellent osseointegration.Based on the study,the 0.4mm pore size resulted in the most rapid cell proliferation and the maximal BV/TV ratio and trabecular bone number of the new bone that ingrew into the porous titanium.To balance the excellent osseointegration and adequate mechanical properties,the optimal structural parameters were 0.4mmpore size with 40%porosity.This porous titanium is very promising for orthopedic applications where compressive and tensile load-bearing is extremely important.

Additive manufacturing techniques and their biomedical applications

Additive manufacturing(AM),also known as three-dimensional(3D)printing,is gaining increasing attention in medical fields,especially in dental and implant areas.Because AM technologies have many advantages in comparison with traditional technologies,such as the ability to manufacture patient-specific complex components,high material utilization,support of tissue growth,and a unique customized service for individual patients,AM is considered to have a large potential market in medical fields.This brief review presents the recent progress of 3D-printed biomedical materials for bone applications,mainly for metallic materials,including multifunctional alloys with high strength and low Young’s modulus,shape memory alloys,and their 3D fabrication by AM technologies.It describes the potential of 3D printing techniques in precision medicine and community health.