Osteointegration Of Bone Implants Research Articles

The Investigation of Bone-Implant Connection and New Bone Formation in Fasting and High-Fatty Diet Rats.

Hyperlipidemia caused by a high-fat diet (HFD) has many adverse effects on the cardiovascular system, including vascular problems. In addition, a HFD also has significant adverse effects on bone health. The aim of this study is to examine bone-implant osteointegration and new bone formation in peri-implant defects in fasting and high-fatty diet applied rats. In this study, 28 female Sprague Dawley rats were used. The rats were divided into four groups, with seven rats in each group: the control group on a normal diet (Group 1) (n = 7), the fasted group (Group 2) (n = 7), the high-fatty diet (HFD) group (Group 3) (n = 7), and the fasted and HFD group (Group 4) (n = 7). Titanium implants with a diameter of 2.5 mm and a length of 4 mm were placed in the right tibia bones of the subjects, and a bone graft corresponding to 2 mm of the implant length was placed in the bone defect applied to the neck region. All rats that continued the administered diet for 12 weeks were sacrificed at the end of the experiment period. The implants and surrounding bone tissue were surgically removed and subjected to biomechanical analysis to assess bone-implant osteointegration and peri-implant new bone formation. It was determined that there was no statistically significant difference between the rats in the control group and the other three groups in terms of bone-implant osteointegration and peri-implant new bone formation (P > 0.05). As a result of this study, it was determined that fasting or maintaining a HFD does not adversely affect bone-implant osteointegration or peri-implant new bone formation in the tibias of rats.

Micromotion and stress shielding between taper fluted and cylindrical femoral stems for Paprosky bone deficiency type IIIB.

Taper fluted and cylindrical femoral stems have been commonly used for revision surgery with femoral bone loss. Shape and material differences between taper fluted and cylindrical confused surgeons whether superiority and inferiority in comparisons especially for type IIIB Paprosky bone deficiency. This study aims to investigate the micromotion between implant and bone interface and stress distribution around the implant in human cadaveric experiments. Paired comparisons of 7 cadavers between taper fluted stem and cylindrical stem were tested under dynamic cyclic loading. The results showed appropriate bone-implant micromotions for bone osteointegration could be observed between both taper fluted and cylindrical stems (85 ± 10μm and 113 ± 80μm respectively, p = 0.59). Taper fluted stem attained the load distribution from the proximal to distal surrounding bone (from 4.92 ± 2.87MPa to 2.14 ± 1.43MPa, p = 0.43), while the cylindrical stem type showed the proximal bone stress shielding (from 2.56 ± 0.76MPa to 5.23 ± 0.77MPa, p = 0.03). Both taper fluted and cylindrical femoral stems provided an adequate initial stability with a proper micromotions for bone-implant osteointegration for type IIIB Paprosky femoral bone loss. The taper fluted femoral stem had better biomechanical advantage in terms of greater stress transfer to periprosthetic bone.

Expression of VEGF and BMP-2 in Osteoblast cells exposed to a combination of polymethylmethacrylate (PMMA) and hydroxyapatite (HAp).

Polymethylmethacrylate (PMMA) has been widely used, but it has several fallback properties in its interaction with bone tissue, so the addition of hydroxyapatite (HAp) material aims to improve the biocompatibility, regeneration process, and osteointegration of bone implants. The HAp material can be sourced from bovine bone and processed through Good Manufacturing Practice from Tissue Bank (HApGMP), and from limestone (CaCO3) processed by Balai Besar Keramik (HApBBK).This study was to observe the expression of vascular endothelial growth factor (VEGF) and Bone morphogenetic protein-2 (BMP2) in cultured osteoblasts exposed to PMMA-HApGMP and PMMA-HApBBK as implant candidate materials. Sample of PMMA and HAp materials with a mixture of PMMA and HApBBK in the first group and a mixture of PMMA and HApGMP in the second group. Twenty-four fetal rat calvarie osteoblast cell cultures were randomly divided into 6 groups: 7- and 14-day control group, 7 and 14 days PMMA-HApGMP group, 7 and 14 days PMMA-HApBBK group. The expression of VEGF and BMP-2 was seen by immunocytochemical examination. The one-way ANOVA with a significance value of 0.000 (p<0.05). BMP-2 and VEGF expression was increased in the 7- and 14-days groups after exposure to PMMA-HApGMP and PMMA-HApBBK. The application of PMMA-HApGMP and PMMA-HApBBK showed an increase in the expression of VEGF and BMP-2 in osteoblast cell cultures which indicates a potential increase in the accelerated angiogenesis and osteogenesis in the bone regeneration process of bone implants.

Mechanical characterization of pore-graded bioactive glass scaffolds produced by robocasting

Abstract Since the discovery of 45S5 Bioglass® by Larry Hench, bioactive glasses have been widely studied as bone substitute materials and, in more recent years, have also shown great promise for producing three-dimensional scaffolds. The development of additive manufacturing techniques and their application in bone tissue engineering allows the design and fabrication of complex structures with controlled porosity. However, achieving strong and mechanically-reliable bioactive glass scaffolds is still a great challenge. Furthermore, there is a relative paucity of studies reporting an exhaustive assessment of other mechanical properties than compressive strength of glass-derived scaffolds. This research work aimed at determining key mechanical properties of silicate SiO2-Na2O-K2OMgO-CaO-P2O5 glass scaffolds fabricated by robocasting and exhibiting a porosity gradient. When tested in compression, these scaffolds had a strength of 6 MPa, a Young’s modulus around 340 MPa, a fracture energy of 93 kJ/m3 and a Weibull modulus of 3, which provides a quantification of the scaffold reliability and reproducibility. Robocasting was a suitable manufacturing method to obtain structures with favorable porosity and mechanical properties comparable to those of the human cancellous bone, which is fundamental regarding osteointegration of bone implants.

Biological Response to Recombinant Human Bone Morphogenetic Protein-2 on Bone-Implant Osseointegration in Ovariectomized Experimental Design.

The aim of this study is to investigate the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) on bone-implant osteointegration in osteoporotic rats. Thirty-six female Wistar rats were randomly divided into 3 groups: sham-operation (SHAM), ovariectomized (OVX), and ovariectomized with rhBMP-2 (OVX + rhBMP-2). The bone density of right tibia was observed with x-ray and the serum alkaline phosphatase (ALP) activity was measured preovariectomy and postovariectomy using an ALP-kit. In OVX + rhBMP-2 group, rhBMP-2 was embedded in the peri-implant area, while SHAM and OVX groups did not contain rhBMP-2. Four and eight weeks after implantation, the rats were killed and the right tibia with implants was taken by x-ray. Histologic changes were investigated by hematoxylin and eosin staining, scanning electron microscope (SEM), and energy dispersive spectrometer examinations. The serum ALP level was significantly higher in ovariectomized rats compared with that before ovariectomy (P < 0.05), while no difference was found in SHAM rats. At 12 weeks after ovariectomy, radiographic and histologic findings showed significant osteoporotic changes in proximal tibial metaphyses of OVX rats, including reduced cortical bone density and enlargement of bone marrow cavity compared with SHAM ones. The results of implantation verified new bone formation around implants in OVX + rhBMP-2 and SHAM groups, indicating favorable bone healing and osseointegration. No bone resorption was found in OVX + rhBMP-2 group, while some soft tissue was observed in bone-implant interface in SHAM group. In OVX group, there was no effective bone-implant osseointegration and mature bone formed around implants, and some implants were even lost due to chronic inflammation. The percentage of calcium and phosphorous atoms was significantly higher and the percentage of sulfur element was significantly lower in peri-implant area in OVX + rhBMP-2 and SHAM groups than that in OVX group. rhBMP-2 could enhance the osseous healing and restore bone-implant osseointegration in osteoporotic rats.

Bioactive poly(etheretherketone) composite containing calcium polyphosphate and multi-walled carbon nanotubes for bone repair: Mechanical property and in vitro biocompatibility

Poly(etheretherketone) exhibits good biocompatibility, excellent mechanical properties, and bone-like stiffness. However, the natural bio-inertness of pure poly(etheretherketone) hinders its applications in biomedical field, especially when direct bone-implant osteo-integration is desired. For developing an alternative biomaterial for load-bearing orthopedic application, combination of bioactive fillers with poly(etheretherketone) matrix is a feasible approach. In this study, a bioactive multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite was prepared through a compounding and injection-molding process for the first time. Bioactive calcium polyphosphate was added to polymer matrix to enhance the bioactivity of the composite, and incorporation of multi-walled carbon nanotubes to composite was aimed to improve both the mechanical property and biocompatibility. Furthermore, the microstructures, surface hydrophilicity, and mechanical property of multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite, as well as the cellular responses of MC3T3-E1 osteoblast cells to this material were investigated. The mechanical testing revealed that mechanical performance of the resulting ternary composite was significantly enhanced by adding the multi-walled carbon nanotubes and the mechanical values obtained were close to or higher than those of human cortical bone. More importantly, cell culture tests showed that initial cell adhesion, cell viability, and osteogenic differentiation of MC3T3-E1 cells were significantly promoted on the multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite. Accordingly, the multi-walled carbon nanotubes/calcium polyphosphate/poly(etheretherketone) composite may be used as a promising bone repair material in dental and orthopedic applications.

Three-Scale Multiphysics Modeling of Transport Phenomena within Cortical Bone

Bone tissue can adapt its properties and geometry to its physical environment. This ability is a key point in the osteointegration of bone implants since it controls the tissue remodeling in the vicinity of the treated site. Since interstitial fluid and ionic transport taking place in the fluid compartments of bone plays a major role in the mechanotransduction of bone remodeling, this theoretical study presents a three-scale model of the multiphysical transport phenomena taking place within the vasculature porosity and the lacunocanalicular network of cortical bone. These two porosity levels exchange mass and ions through the permeable outer wall of the Haversian-Volkmann canals. Thus, coupled equations of electrochemohydraulic transport are derived from the nanoscale of the canaliculi toward the cortical tissue, considering the intermediate scale of the intraosteonal tissue. In particular, the Onsager reciprocity relations that govern the coupled transport are checked.

Covalent attachment of cell-adhesive peptide Gly-Arg-Gly-Asp (GRGD) to poly(etheretherketone) surface by tailored silanization layers technique

Poly(etheretherketone) (PEEK) is a rigid semicrystalline polymer that combines excellent mechanical properties, broad chemical resistance and bone-like stiffness and is widely used in biomedical fields. However, PEEK is naturally bioinert, leading to limited biomedical applications, especially when a direct bone-implant osteointegration is desired. In this study, a three-step reaction procedure was employed to immobilize the cell-adhesive peptide Gly-Arg-Gly-Asp (GRGD) on the surface of PEEK sheet by covalent chemical attachment to favor cell adhesion and proliferation. First, hydroxylation-pretreated PEEK surfaces were silanized with 7-Oct-1-enyltrichlorosilane (OETS) in dry cyclohexane, resulting in a silanization layer with terminal ethenyl. Second, the terminal ethylenic double bonds of the silanization layer on PEEK surface were converted to carboxyl groups through acidic potassium manganate oxidation. Finally, GRGD was covalently attached by carbodiimide mediated condensation between the carboxyl on PEEK surface and amine presents in GRGD. X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, surface profiler and water contact angle measurements were applied to characterize the modified surfaces. The effect of cells attachment and proliferation on each specimen was investigated. Pre-osteoblast cells (MC3T3-E1) attachment, spreading and proliferation were improved effectively on GRGD-modified PEEK surface. PEEK modified with GRGD on its surface has potential use in orthopedic or dental implants.

The influence of iatrogenic mobilization in the initial stage of implant installation on final osteointegration

Purpose: The aim of present investigation was to find out the influence of several times iatrogenic mobilization in the initial stage of implant installation on bone-implant osteointegration. Materials and methods: The experimental implants (3.75 mm in diameter, 8.0 mm in length) were made of commercially pure (Grade IV) titanium, and were treated with RBM (MegaGen� : Ca-P) on lower 4.0 mm part. Only lower part of implant was inserted to bone and the implants were nonsubmerged. The 130 implants (two in each tibia) were inserted into the monocortical tibias of 33 rabbits which each weighed more than 3.5 kg (Female, New Zealand White). According to the removal torque interval, the groups were divided into 13 groups, group I (1 day), group II (1 day + 2 days), group III (1 day + 2 days + 3 days), group IV (1 day + 2 days + 3 days + 4 days), group V (2 days), group VI (2 days + 4 days), group VII (2 days + 4 days + 6 days), group VIII (2 days + 4 days + 6 days + 8 days), group IX (4 days), group X (4 days + 7 days), group XI (4 days + 7 days + 10 days), group XII (4 days + 7 days + 10 days + 14 days) and control group. In the control group, the removal torque was measured at 8 weeks with a digital torque gauge (Mark-10, USA). In the experimental groups, the removal torque was given once, twice, three times or four times by experiment design before the final removal torque and the value was measured each time. The implants were then screwed back to their original positions. All the experimental groups were given a final healing time of 8 weeks after placement, in which values were compared with the control groups and the 1st, 2nd, 3rd or 4th removal torque values in each experimental group. Results: In comparison of the final removal torque tests among experimental groups, the removal torque value of experimental groups except group XII were not statistically different that of control group. And the values of group I and II were significantly higher than the values of group VI, VIII, X, XI, and XII. In addition, the values of group III, IV, and V were significantly higher than group XI and XII. In comparison of the removal torque in the each experimental group, the final removal torque were significantly higher in all groups except group VIII, X, XI, and XII. Conclusion: If sufficient healing time was allowed, a few mobilization of fixture at the very early stage after the implant placement in the rabbits didn't interrupt the final bone to implant osseointegration. (J Korean Acad Prosthodont 2014;52:105-12)

Nanostructured Si-substituted hydroxyapatite coatings for biomedical applications

In the present work, the Si-HAp coatings were deposited on titanium substrates by Pulsed Laser Deposition technique. For deposition, the Si-HAp targets (1.4wt.% of Si), produced starting from wet synthesized powders, were used. The properties of coatings were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and Vickers microhardness. The obtained Si-HAp coatings presented a nanosized structure, proper thickness and hardness for applications in orthopedical and dental surgery, aimed at improving the stability and the osteointegration of bone implants.

Current trends in the enhancement of biomaterial osteointegration: biophysical stimulation.

To enhance bone implant osteointegration, many strategies for improving biomaterial properties have been developed which include optimization of implant material, implant design, surface morphology and osteogenetic coatings. Other methods that have been attempted to enhance endogenous bone healing around biomaterials are different forms of biophysical stimulations such as pulsed electromagnetic fields (PEMFs) and low intensity pulsed ultrasounds (LIPUS), which were initially developed to accelerate fracture healing. To aid in the use of adjuvant biophysical therapies in the management of bone-implant osteointegration, the present authors reviewed experimental and clinical studies published in the literature over the last 20 years on the combined use of biomaterials and PEMFs or LIPUS, and summarized the methodology, and the possible mechanism of action and effectiveness of the different biophysical stimulations for the enhancement of bone healing processes around bone implanted biomaterials.