Tensile and torsional shear strength of the bone implant interface of titanium implants in the rabbit

Highly-porous metallic implant onlay materials (specifically those containing surface pores that intersect beneath the onlay surface) have been investigated recently for their potential to reduce bone resorption and to improve the overall stability of the implant. In the current study, sub-surface interconnectivity of high-aspect-ratio pores was created directly in the substrate of an implant material using wire electrical discharge machining (EDM). This technique was used to produce intersecting pores with diameters of 180-250 μm on a clinically relevant implant material—commercially pure (CP) Grade 4 Ti—with a very high degree of control over pore morphology. These pores resulted in no significant microstructural modification to the surrounding Ti, and the inner pore surfaces could be thermally oxidized to produce a microrough, bioactive TiO2 layer. Finite element analysis of Ti models containing these EDM-attainable intersecting pore geometries suggested they produce higher bone/implant interface strengths and lower susceptibility to stress shielding of the surrounding bone as compared with models containing simpler surface geometries. In vitro experiments using mesenchymal stem cells (MSCs) demonstrated mineralized tissue ingrowth of ∼ 300 μm into EDM-produced pores. This amount of ingrowth is expected to allow for full interlocking of mineralized tissue and implant given the proper pore structure design.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Finite element analysis and cellular studies on advanced, controlled porous structures with subsurface continuity in bio-implantable titanium alloys

Lambert

Ankem

Wyatt

et al. 2013

“…Surface roughness and the arithmetic mean of roughness height of cylinder samples (Ra) were measured using a Perthen laser profilometer. In order to reduce the effect of surface roughness on push‐out testing results,13, 14 implanted cylinders were limited to those with Ra ranging from 4 to 6 μm.…”

Section: Methodsmentioning

confidence: 99%

Push-out testing and histological evaluation of glass reinforced hydroxyapatite composites implanted in the tibia of rabbits

Lopes

Santos

Monteiro

et al. 2000

In vitro and in vivo bioactivity studies were performed to assess the biocompatibility of CaO-P2O5 glass-reinforced hydroxyapatite (GR-HA) composites. The ability to form an apatite layer by soaking in simulated body fluid (SBF) was examined and surfaces were characterized using FTIR reflection and thin-film X-ray diffraction analyses. Qualitative histology, histomorphometric measurements, and push-out testing were performed in a rabbit model for characterizing bone/implant bonding. Under the in vitro conditions using SBF, an apatite layer could not be formed on GR-HA composites within 8 weeks. Results of push-out testing showed bonding between the composites and bone, ranging from 130-145 N after 2 weeks of implantation. After the longest implantation period, 16 weeks, the GR-HA composite prepared with the higher content of CaO-P2O5 glass showed the highest bonding force, 606 +/- 45 N, compared to 459 +/- 30 N for sintered HA. Development of immature bone and modifications in the turnover of a more mature bone on the surface of GR-HA composites were similar to those on sintered HA.

“…Currently, there are three types of tests for evaluating biomaterial-tissue interfaces: push out test, tensile test, [22][23][24][25][26][27][28] and fracture toughness test. Among these tests, the push-out and tensile tests are akin to structural tests, and are unlikely to yield intrinsic fracture properties of the interfaces.…”

Section: Introductionmentioning

confidence: 99%

A mixed mode fracture toughness test of bone-biomaterial interfaces

Wang

Agrawal

2000

Tissue-biomaterial interfacial bonding plays a significant role in the success of biomaterials used for load-bearing orthopedic and dental prostheses. The objective of this study was to develop a physically sound and practically effective technique for assessment of the strength of bone-biomaterial interfaces under mixed mode loading. A single-edge notched sandwich specimen was developed for this purpose, wherein a bilayer specimen comprising the interface between tissue and biomaterial was sandwiched between two holders and loaded under mixed modes. First, a closed form solution was derived for the sandwich specimen under the assumption of linear elasticity, based on a general solution for sandwich structures reported in the literature. Then, a correction factor was determined for the solution using finite element models to compensate for errors induced by finite interlayer thickness. Moreover, using the same FEA models, it was found that crack closure may occur when the shear component is dominant at the crack. However, its effects were estimated to be limited and negligible. Furthermore, as an example, the strength of a bone/dental cement interface under different loading modes was tested using this sandwich technique. It is expected that the mixed mode technique can provide an effective means for investigators to study the mechanical integrity of bone-biomaterial interfaces under complex loading conditions.