Histological and Bone Morphometric Evaluation of Osseointegration Aspects by Alkali Hydrothermally-Treated Implants

Influence of structural parameters of 3D-printed triply periodic minimal surface gyroid porous scaffolds on compression performance, cell response, and bone regeneration

In this study, multi-scale triply periodic minimal surface (TPMS) porous scaffolds with uniform and radial gradient distribution on pore size were printed based on the selective laser melting technology, and the influences of porosity, pore size and radial pore size distribution on compression mechanical properties, cell behavior, and bone regeneration behavior were analyzed. The results showed that the compression performance of the uniform porous scaffolds with high porosity was similar to that of cancellous bone of pig tibia, and the gradient porous scaffolds have higher elastic modulus and compressive toughness. After 4 days of cell culture, cells were distributed on the surface of scaffolds mostly, and the number of adherent cells was higher on the small pore size porous scaffolds; After 7 days, the area and density of cell proliferation on the scaffolds were improved; After 14 days, the cells on the small pore size scaffolds tended to migrate to adjacent pores. Animal implantation experiments showed that collagen fiber osteoid was intermittent on scaffolds with high porosity and large pore size, which was not conducive to bone formation. The appropriate pore size and porosity of bone regeneration were 792 um and 83%, respectively, and the regenerative ability of gradient pore size was better than that of uniform pore size. Our study explains the rules of TPMS gyroid structure parameters on compression performance, cell response and bone regeneration, and provides a reference value for the design of bone repair scaffolds for clinical orthopedics.

Development of a novel bioactive titanium membrane with alkali treatment for bone regeneration

This study evaluates a bioactive titanium membrane with alkali treatment for stimulating apatite formation and promoting bone regeneration. The titanium thin membranes were either treated with NaOH (alkali-group) or untreated (control). Each sample were incubated in simulated body fluid. Subsequently, the composition of the surface calcium deposition, its weight increase ratio, and optical absorbance were evaluated. Then, the bone defect was trephined on the rats calvaria and covered with each sample membrane or no membrane, and the bone tissue area ratio (BTA) and bone membrane contact ratio (BMC) were evaluated. The spherical crystalline precipitates formed in both groups. In the alkali-group after 21 days, the precipitates matured, forming apatite-like precipitates. The alkali-group showed higher Ca and P contents and weight increase ratios than the control. The alkali-group exhibited a higher BMC than the control in the central area. Thus, this novel membrane has high apatite-forming and bone regeneration abilities.

Protruding Nanostructured Surfaces for Antimicrobial and Osteogenic Titanium Implants

Protruding nanostructured surfaces have gained increasing interest due to their unique wetting behaviours and more recently their antimicrobial and osteogenic properties. Rapid development in nanofabrication techniques that offer high throughput and versatility on titanium substrate open up the possibility for better orthopaedic and dental implants that deter bacterial colonisation while promoting osteointegration. In this review we present a brief overview of current problems associated with bacterial infection of titanium implants and of efforts to fabricate titanium implants that have both bactericidal and osteogenic properties. All of the proposed mechano-bactericidal mechanisms of protruding nanostructured surfaces are then considered so as to explore the potential advantages and disadvantages of adopting such novel technologies for use in future implant applications. Different nanofabrication methods that can be utilised to fabricate such nanostructured surfaces on titanium substrate are briefly discussed.

The development of novel bioactive porous titanium as a bone reconstruction material

Porous titanium fabricated by the resin-impregnated titanium substitute technique has good mechanical strength and osteoconduction. The alkali treatment of the titanium surface creates a bioactive surface. Alkali-treated porous titanium is expected to accelerate bone formation. The purpose of this study was to evaluate the bone reconstruction ability of alkali-treated porous titanium. Porous titanium (85% porosity) was treated with an alkali solution (5 N NaOH, 24 h). To assess material properties, we analyzed the surface structure by scanning electron microscopy (SEM) and mechanical strength testing. To assess bioactivity, each sample was soaked in a simulated body fluid (Hank's solution) for 7 days. Surface observations, weight change ratio measurement (after/before being soaked in Hank's solution) and surface elemental analysis were performed. We also designed an in vivo study with rabbit femurs. After 2 and 3 weeks of implantation, histological observations and histomorphometric bone formation ratio analysis were performed. All data were statistically analyzed using a Student's t-test (P < 0.05) (this study was approved by the Hiroshima University animal experiment ethics committee: A11-5-5). Non-treated porous titanium (control) appeared to have a smooth surface and the alkali-treated porous titanium (ATPT) had a nano-sized needle-like rough surface. ATPT had similar mechanical strength to that of the control. After soaking into the Hank's solution, we observed apatite-like crystals in the SEM image, weight gain, and high Ca and P contents in ATPT. There was significant bone formation at an early stage in ATPT compared with that in control. It was suggested that the alkali-treated porous titanium had a bioactive surface and induced bone reconstruction effectively. This novel bioactive porous titanium can be expected to be a good bone reconstruction material.

Porous titanium fabricated by the resin-impregnated titanium substitute technique has good mechanical strength and osteoconduction.