Bone ingrowth of various porous titanium scaffolds produced by a moldless and space holder technique: anin vivostudy in rabbits

Abstract

Porous titanium has long been desired as a bone substitute material because of its ability to reduce the stress shielding in supporting bone. In order to achieve the various pore structures, we have evolved a moldless process combined with a space holder technique to fabricate porous titanium. This study aims to evaluate which pore size is most suitable for bone regeneration using our process. The mixture comprising Ti powder, wax binder and PMMA spacer was prepared manually at 70 °C which depended on the mixing ratio of each group. Group 1 had an average pore size of 60 μm, group 2 had a maximum pore size of 100 μm, group 3 had a maximum pore size of 200 μm and group 4 had a maximum pore size of 600 μm. These specimens were implanted into rabbit calvaria for three and 20 weeks. Thereafter, histomorphometrical evaluation was performed. In the histomorphometrical evaluation after three weeks, the group with a 600 μm pore size showed a tendency to greater bone ingrowth. However, after 20 weeks the group with a pore size of 100 μm showed significantly greater bone ingrowth than the other groups. This study suggested that bone regeneration into porous titanium scaffolds is pore size-dependent, while bone ingrowth was most prominent for the group with 100 μm-sized pores after 20 weeks in vivo.

Influence of macroporosity on NIH/3T3 adhesion, proliferation, and osteogenic differentiation of MC3T3‐E1 over bio‐functionalized highly porous titanium implant material

“…Gauthier et al showed that after 8 weeks of in vivo implantation, better bone ingrowth was achieved for ceramic scaffolds with macropores of 565 μm than 300 μm. On the other hand, Prananingrum et al showed that the pore size of 100 µm presented the greatest amount of bone ingrowth, and the rate of bone ingrowth significantly decreased as the pore size increased on Ti scaffolds. Torres‐Sanchez et al concluded that small pores offer a larger surface area and at early days of culture this pore size is favorable for the attachment stage.…”

“…Titanium is a widely used material in biomedical implants due to the combination of the required properties, as excellent corrosion resistance, adequate biocompatibility, and mechanical properties . However, the differences between the Young's modulus of the Ti implants and the bone (110 and 10–30 GPa, respectively) leads to stress shielding effect on the supporting bone .…”

“…Titanium is a widely used material in biomedical implants due to the combination of the required properties, as excellent corrosion resistance, adequate biocompatibility, and mechanical properties . However, the differences between the Young's modulus of the Ti implants and the bone (110 and 10–30 GPa, respectively) leads to stress shielding effect on the supporting bone . The use of highly porous structures with tailored porosity are becoming popular for implant materials particularly due to their adjustable Young's modulus to be similar to the bone, and at the same time, improved implant fixation …”

Gelatin freeze casting of biomimetic titanium alloy with anisotropic and gradient pore structure

“…Pore sizes of 100µm have been reported to be favourable for bone tissue ingrowth (Prananingrum et al 2016), and the scaffolds produced here are thus of suitable dimensions for bone ingrowth, and can moreover be tuned for precise control of dimensions.…”

Scaffolds and coatings for bone regeneration

“…Moreover, cells from the surrounding must be able to penetrate. Pore size is, thus, an important feature since if the pores are too small, pore occlusion by the cells will happen and it is also an important factor for protein adsorption, cellular migration and osteoconduction [11,71]. Pore sizes greater than 300 µm are recommended for bone ingrowth in comparison with smaller pore size [67,[72][73][74].…”