Direct Bone Apposition Research Articles

Benchmark performance of anodized vs. sandblasted implant surfaces in an acute dehiscence type defect animal model.

Crestal bone formation represents a crucial aspect of the esthetic and biological success of dental implants. This controlled preclinical study analyzed the effect of implant surface and implant geometry on de novo crestal bone formation and osseointegration. Histological and histomorphometrical analysis was performed to compare three implant groups, that is, (1) a novel, commercially available, gradient anodized implant, (2) a custom-made geometric replica of implant "1," displaying a superhydrophilic micro-rough large-grit sandblasted and acid-etched surface, and (3) a commercially available implant, having the same surface as "2" but a different implant geometry. The study applied a standardized buccal acute-type dehiscence model in minipigs with observation periods of 2 and 8 weeks of healing. The amount of newly formed crestal bone (BATA) around control groups (2) and (3) was significantly increased when compared to the test group (1) at the 8 weeks of healing time point. Similar results were obtained for all parameters related to osseointegration and direct bone apposition, to the implant surface (dBIC, VBC, and fBIC), demonstrating superior osseointegration of the moderately rough, compared to the gradient anodized functionalization. After 2 weeks, the osseointegration (nBIC) was found to be influenced by implant geometry with group (3) outperforming groups (1) and (2) on this parameter. At 8 weeks, nBIC was significantly higher for groups (2) and (3) compared to (1). The extent (BATA) of de novo crestal bone formation in the acute-type dehiscence defects was primarily influenced by implant surface characteristics and their ability to promote osseointegration and direct bone apposition. Osseointegration (nBIC) of the apical part was found to be influenced by a combination of surface characteristics and implant geometry. For early healing, implant geometry may have a more pronounced effect on facilitating osseointegration, relative to the specific surface characteristics.

Surface Characterization of PEKK Modified by stron-tium–hydroxyapatite coating as implant material Via the magnetron sputtering Deposition technique

Background: The best material for dental implants is polyetherketoneketone (PEKK). However, this substance is neither osteoinductive nor osteoconductive, preventing direct bone apposition. Modifying the PEKK with bioactive elements like strontium hydroxyapatite is one method to overcome this (Sr-HA). Due to the technique's capacity to provide better control over the coating's properties, RF magnetron sputtering has been found to be a particularly useful technique for deposition.
 Materials and methods : With specific sputtering conditions, the RF magnetron technique was employed to provide a homogeneous and thin coating on Polyetherketoneketone substrates.. the coatings were characterized by Contact angle, adhesion test, X-ray diffraction (XRD), atomic force microscope and Elemental Analysis with Energy Dispersive X-Ray (EDX)
 Results : indicated that strontium hydroxyapatite had successfully deposited onto the surface with significant improvement in the wettability value to provide a suitable environment for cell attachment, spreading, proliferation, and differentiation
 Conclusion: Coating PEKK with RF magnetron sputtering can provide homogeneous surfaces laying the groundwork for improving PEKK's potential bioactivity, such as surface wettability. Wetting qualities are critical in implantable materials and are used to predict future osseointegration success.

High-strength, porous additively manufactured implants with optimized mechanical osseointegration

Optimization of porous titanium alloy scaffolds designed for orthopedic implants requires balancing mechanical properties and osseointegrative performance. The tradeoff between scaffold porosity and the stiffness/strength must be optimized towards the goal to improve long term load sharing while simultaneously promoting osseointegration. Osseointegration into porous titanium implants covering a wide range of porosity (0%–90%) and manufactured by laser powder bed fusion (LPBF) was evaluated with an established ovine cortical and cancellous defect model. Direct apposition and remodeling of woven bone was observed at the implant surface, as well as bone formation within the interstices of the pores. A linear relationship was observed between the porosity and benchtop mechanical properties of the scaffolds, while a non-linear relationship was observed between porosity and the ex vivo cortical bone-implant interfacial shear strength. Our study supports the hypothesis of porosity dependent performance tradeoffs, and establishes generalized relationships between porosity and performance for design of topological optimized implants for osseointegration. These results are widely applicable for orthopedic implant design for arthroplasty components, arthrodesis devices such as spinal interbody fusion implants, and patient matched implants for treatment of large bone defects.

The Direct 3D Printing of Functional PEEK/Hydroxyapatite Composites via a Fused Filament Fabrication Approach.

The manufacture of polyetheretherketone/hydroxyapatite (PEEK/HA) composites is seen as a viable approach to help enhance direct bone apposition in orthopaedic implants. A range of methods have been used to produce composites, including Selective Laser Sintering and injection moulding. Such techniques have drawbacks and lack flexibility to manufacture complex, custom-designed implants. 3D printing gets around many of the restraints and provides new opportunities for innovative solutions that are structurally suited to meet the needs of the patient. This work reports the direct 3D printing of extruded PEEK/HA composite filaments via a Fused Filament Fabrication (FFF) approach. In this work samples are 3D printed by a custom modified commercial printer Ultimaker 2+ (UM2+). SEM-EDX and µCT analyses show that HA particles are evenly distributed throughout the bulk and across the surface of the native 3D printed samples, with XRD highlighting up to 50% crystallinity and crystalline domains clearly observed in SEM and HR-TEM analyses. This highlights the favourable temperature conditions during 3D printing. The yield stress and ultimate tensile strength obtained for all the samples are comparable to human femoral cortical bone. The results show how FFF 3D printing of PEEK/HA composites up to 30 wt% HA can be achieved.

The Surface Characterisation of Polyetheretherketone (PEEK) Modified via the Direct Sputter Deposition of Calcium Phosphate Thin Films

Polyetheretherketone (PEEK) has emerged as the material of choice for spinal fusion devices, replacing conventional materials such as titanium and its alloys due to its ability to easily overcome a lot of the limitations of traditional metallic biomaterials. However, one of the major drawbacks of this material is that it is not osteoinductive, nor osteoconductive, preventing direct bone apposition. One way to overcome this is through the modification of the PEEK with bioactive calcium phosphate (CaP) materials, such as hydroxyapatite (HA–Ca10(PO4)6(OH)2). RF magnetron sputtering has been shown to be a particularly useful technique for the deposition of CaP coatings due to the ability of the technique to provide greater control of the coating’s properties. The work undertaken here involved the deposition of HA directly onto PEEK via RF magnetron at a range of deposition times between 10–600 min to provide more bioactive surfaces. The surfaces produced have been extensively characterised using X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), stylus profilometry, and Time of Flight Secondary Ion Mass Spectrometry (ToFSIMS). XPS results indicated that both Ca and P had successfully deposited onto the surface, albeit with low Ca/P ratios of around 0.85. ToFSIMS analysis indicated that Ca and P had been homogeneously deposited across all the surfaces. The SEM results showed that the CaP surfaces produced were a porous micro-/nano-structured lattice network and that the deposition rate influenced the pore area, pore diameter and number of pores. Depth profiling, using ToFSIMS, highlighted that Ca and P were embedded into the PEEK matrix up to a depth of around 1.21 µm and that the interface between the CaP surface and PEEK substrate was an intermixed layer. In summary, the results highlighted that RF magnetron sputtering can deliver homogenous CaP lattice-like surfaces onto PEEK in a direct, one-step process, without the need for any interlayers, and provides a basis for enhancing the potential bioactivity of PEEK.

Bone grafted with β‐TCP granules in the rabbit: A microcomputed tomographic, histologic, Raman microspectrometric, and Raman imaging study

AbstractBone grafting with synthetic substitutes is now the preferred technique in maxillofacial surgery. The biocompatibility of biomaterials such as beta‐tricalcium phosphate (β‐TCP) necessitates animal experimentation. Here, six rabbits received β‐TCP granules in a hole drilled in the femoral condyle and were compared with ungrafted holes with a similar critical size defect on the control‐lateral side. Microcomputed tomography confirmed that new bone trabeculae had invaded the grafted zone after 28 days, whereas only minimal remodeling had occurred at the margins of the hole in control rabbits. Histological sections, after polymethylmethacrylate (pMMA) embedding, evidenced a direct apposition of bone onto the granules. In some areas, osteoid tissue remained unmineralized, sandwiched between the biomaterial and fully calcified bone. Raman analysis was used to characterize the differences between the calcium/phosphate biomaterial and the bone matrix containing hydroxyapatite. Luminescence of β‐TCP was evidenced with a 785‐nm laser used for biological analysis but not with a 532‐nm laser. The ν1 phosphate allowed a clear differentiation of bone and the biomaterial as the subpeaks were not similar (960 cm−1 for bone, 949 and 970 cm−1 for β‐TCP). Hydration (derived from identification of pMMA at 813 cm−1) and crystallinity could be determined. Raman imaging allowed the precise localization of these different peaks or ratios; luminescence peaks of β‐TCP also allowed a clear differentiation of the material from bone.

Regeneration enhanced in critical-sized bone defects using bone-specific extracellular matrix protein.

Extracellular matrix (ECM) products have the potential to improve cellular attachment and promote tissue-specific development by mimicking the native cellular niche. In this study, the therapeutic efficacy of an ECM substratum produced by bone marrow stem cells (BM-MSCs) to promote bone regeneration in vitro and in vivo were evaluated. Fluorescence-activated cell sorting analysis and phenotypic expression were employed to characterize the in vitro BM-MSC response to bone marrow specific ECM (BM-ECM). BM-ECM encouraged cell proliferation and stemness maintenance. The efficacy of BM-ECM as an adjuvant in promoting bone regeneration was evaluated in an orthotopic, segmental critical-sized bone defect in the rat femur over 8 weeks. The groups evaluated were either untreated (negative control); packed with calcium phosphate granules or granules+BM-ECM free protein and stabilized by collagenous membrane. Bone regeneration in vivo was analyzed using microcomputed tomography and histology. in vivo results demonstrated improvements in mineralization, osteogenesis, and tissue infiltration (114 ± 15% increase) in the BM-ECM complex group from 4 to 8 weeks compared to mineral granules only (45 ± 21% increase). Histological observations suggested direct apposition of early bone after 4 weeks and mineral consolidation after 8 weeks implantation for the group supplemented with BM-ECM. Significant osteoid formation and greater functional bone formation (polar moment of inertia was 71 ± 0.2 mm4 with BM-ECM supplementation compared to 48 ± 0.2 mm4 in untreated defects) validated in vivo indicated support of osteoconductivity and increased defect site cellularity. In conclusion, these results suggest that BM-ECM free protein is potentially a therapeutic supplement for stemness maintenance and sustaining osteogenesis.

A review on plasma sprayed titanium and hydroxyapatite coatings on polyetheretherketone implants

Polyetheretherketone (PEEK) is a biocompatible polymer with good mechanical strength, thermal and chemical stability and is suitable for magnetic resonance and X-ray imaging. Moreover, density and elasticity of PEEK is closer to bones compared to metals. Nevertheless, the hydrophobicity of the PEEK surface causes a soft tissue formation at the bone/implant interface that prevents direct bone apposition. Although numerous methods have been developed for improving PEEK's bioactivity, the most widely used and accepted method have been coating the surface with a thin layer of osseointegrative material by thermal spraying. Most widely used coating materials in the manufacture of orthopaedic implants have been hydroxyapatite (HAp) and titanium. Thus, this review focuses on the recent progress on HAp and Ti coatings deposited by plasma spraying methods on PEEK implants.

A review on plasma sprayed titanium and hydroxyapatite coatings on polyetheretherketone implants

Polyetheretherketone (PEEK) is a biocompatible polymer with good mechanical strength, thermal and chemical stability and is suitable for magnetic resonance and X-ray imaging. Moreover, density and elasticity of PEEK is closer to bones compared to metals. Nevertheless, the hydrophobicity of the PEEK surface causes a soft tissue formation at the bone/implant interface that prevents direct bone apposition. Although numerous methods have been developed for improving PEEK's bioactivity, the most widely used and accepted method have been coating the surface with a thin layer of osseointegrative material by thermal spraying. Most widely used coating materials in the manufacture of orthopaedic implants have been hydroxyapatite (HAp) and titanium. Thus, this review focuses on the recent progress on HAp and Ti coatings deposited by plasma spraying methods on PEEK implants.

Medial Closing-Wedge Distal Femoral Osteotomy for Genu Valgum With Lateral Compartment Disease

Lateral compartment disease combined with valgus alignment can lead to progressive knee joint degeneration. In the symptomatic patient with isolated lateral compartment disease, a varus-producing distal femoral osteotomy can unload the diseased lateral compartment. This osteotomy may be combined with other cartilage or meniscal restorative techniques to optimize knee joint preservation and pain relief. The osteotomy can be performed with a medial closing-wedge or lateral opening-wedge technique. Both techniques have been reported to improve knee-related quality of life in patients with lateral compartment disease. Advantages of the medial closing-wedge technique are direct bone apposition leading to inherent stability of the construct, as well as reliable bony healing, and less hardware irritation. Advantages of the lateral opening-wedge technique are a single bony cut and therefore more of an ability to adjust correction intraoperatively. However, this technique requires bone grafting and has a high rate of hardware irritation or removal. We present a surgical technique for the medial closing-wedge distal femoral osteotomy using an anteromedial-distal femoral locking plate.

163 - The Bone: Implant Interface in Loaded and Unloaded Models

BACKGROUND CONTEXT: PEEK cages have a long clinical history for successful fusion and well-established manufacturing processes. There does however remain a concern with the hydrophobic nature of this semi-crystalline thermoplastic and the nonreactive fibrous tissue layer reported in preclinical and clinical studies. Bulk incorporation of a hydroxyapatite (HA), an osteoconductive material, is a potential solution to address the fibrous tissue interface and encourage direct bone apposition.

Does PEEK/HA Enhance Bone Formation Compared With PEEK in a Sheep Cervical Fusion Model?

BackgroundPolyetheretherketone (PEEK) has a wide range of clinical applications but does not directly bond to bone. Bulk incorporation of osteoconductive materials including hydroxyapatite (HA) into the PEEK matrix is a potential solution to address the formation of a fibrous tissue layer between PEEK and bone and has not been tested.Questions/purposesUsing in vivo ovine animal models, we asked: (1) Does PEEK-HA improve cortical and cancellous bone ongrowth compared with PEEK? (2) Does PEEK-HA improve bone ongrowth and fusion outcome in a more challenging functional ovine cervical fusion model?MethodsThe in vivo responses of PEEK-HA Enhanced and PEEK-OPTIMA® Natural were evaluated for bone ongrowth in the form of dowels implanted in the cancellous and cortical bone of adult sheep and examined at 4 and 12 weeks as well as interbody cervical fusion at 6, 12, and 26 weeks. The bone-implant interface was evaluated with radiographic and histologic endpoints for a qualitative assessment of direct bone contact of an intervening fibrous tissue later. Gamma-irradiated cortical allograft cages were evaluated as well.ResultsIncorporating HA into the PEEK matrix resulted in more direct bone apposition as opposed to the fibrous tissue interface with PEEK alone in the bone ongrowth as well as interbody cervical fusions. No adverse reactions were found at the implant–bone interface for either material. Radiography and histology revealed resorption and fracture of the allograft devices in vivo.ConclusionsIncorporating HA into PEEK provides a more favorable environment than PEEK alone for bone ongrowth. Cervical fusion was improved with PEEK-HA compared with PEEK alone as well as allograft bone interbody devices.Clinical RelevanceImproving the bone–implant interface with a PEEK device by incorporating HA may improve interbody fusion results and requires further clinical studies.

Guided bone regeneration using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-cross-linked type-I collagen membrane with biphasic calcium phosphate at rabbit calvarial defects.

BackgroundIn-vitro and animal studies using EDC cross-linked membranes have shown great resistance to enzymatic digestion as well as low cytotoxicity, and indicated its potential expediency as a barrier membrane for guided bone regeneration (GBR). The purpose of this study was to evaluate the efficacy, biocompatibility and degradation kinetics of a novel 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-cross-linked type I collagen membrane for regeneration of rabbit calvarial defects. EDC cross-linked type I collagen membrane and macroporous biphasic calcium phosphate (MBCP) consisting of 60 % hydroxyapatite and 40 % β-tricalcium phosphate were used in this study. Four circular defects (ø = 8 mm) were created in each calvarium of 12 male white rabbits. The experimental groups randomly allocated to the defects were as follows – (1) sham control, (2) EDC-cross-linked collagen membrane (EDC membrane), (3) bone graft (BG), and (4) bone graft with collagen membrane (B-EDC membrane). Specimens were harvested at 2 weeks (n = 6) and 8 weeks (n = 6) postoperatively for observational histology and histometrical analysis.ResultThe histologic observation showed close adaptation of the EDC membrane to the defect perimeters along with vascularization of the membrane at 2 weeks. Direct apposition of new bone on to the collagen matrix could be observed displaying adequate tissue integration. Collapsing of the central portion of the membrane could be seen in the EDC membrane group, and both BG and B-EDC membrane groups showed greater total augmented area and new bone area than the EDC membrane group. The membrane was largely unresorbed at 2 weeks; and at 8 weeks the overall shape of the membrane was still maintained suggesting sustained barrier function at 8 weeks.ConclusionWithin the limits of this study, it may be concluded that EDC-cross-linked collagen membrane is a safe biomaterial with adequate tissue integration and resorption kinetics to support bone regeneration when used in conjunction with bone filler.

The interface between nacre and bone after implantation in the sheep: a nanotomographic and Raman study

Orthopedic bone devices can be prepared from the shells of giant pearl oysters. Nacre is biocompatible and composed of calcium carbonate (aragonite). Direct welding of bone onto the biomaterial surface has been reported but poorly investigated. Nacre from Pinctada maxima was used to prepare plates, screws and rods. Five sheep were implanted in the first metatarsus under general anesthesia and killed 2 months later. Bones were harvested and fixed in formalin. Analysis was performed by nanotomography and histology after embedding in poly(methyl methacrylate). Polished sections were imaged by scanning electron microscopy then analyzed on a Raman microscope. Nanotomography and histology evidenced the newly apposed bone composed of thin trabeculae with a lower mineralization than mature bone. Erosion of the nacre was also easily observed. The bone/nacre interface presented a characteristic toothed‐comb appearance. Raman spectroscopy identified the typical bands of aragonite (1091 and 711 cm−1) in the devices. At a distance from the interface, the bone matrix presented the typical bands of hydroxyapatite at 960, 1044 and 594–610 cm−1 with the amide bands of collagen at 1250 cm−1. At the bone/nacre interface, a phosphate‐rich layer was observed without proteins. The newly formed bone units exhibited a band at 1075 cm−1 corresponding to a high amount of B‐carbonate substitution. The carbonate/phosphate ratio decreased between new and mature bone, and crystallinity was improved. Raman spectroscopy confirmed the modifications of the bone matrix around the nacre implant and the direct apposition of bone without an interposing organic layer between the calcium carbonate (nacre) and the calcium phosphate (hydroxyapatite). Copyright © 2014 John Wiley & Sons, Ltd.

Increased bone remodelling around titanium implants coated with chondroitin sulfate in ovariectomized rats

Coating titanium implants with artificial extracellular matrices based on collagen and chondroitin sulfate (CS) has been shown to enhance bone remodelling and de novo bone formation in vivo. The aim of this study was to evaluate the effect of estrogen deficiency and hormone replacement therapy (HRT) on the osseointegration of CS-modified Ti implants. 30 adult female, ovariectomized Wistar rats were fed either with an ethinyl-estradiol-rich diet (E) to simulate a clinical relevant HRT or with a genistein-rich diet (G) to test an alternative therapy based on nutritionally relevant phytoestrogens. Controls (C) received an estrogen-free diet. Uncoated titanium pins (Ti) or pins coated with type-I collagen and CS (Ti/CS) were inserted 8weeks after ovarectomy into the tibia. Specimens were retrieved 28days after implantation. Both the amount of newly formed bone and the affinity index (P<0.05) were moderately higher around Ti/CS implants as compared to uncoated Ti. The highest values were measured in the G-Ti/CS and E-Ti/CS groups, the lowest values for the E-Ti and G-Ti controls. Quantitative synchrotron radiation micro-computed tomography (SRμCT) revealed the highest increase in total bone formation around G-Ti/CS as compared to C-Ti (P<0.01). The effects with respect to direct bone apposition were less pronounced with SRμCT. Using scanning nanoindentation, both the indentation modulus and the hardness of the newly formed bone were highest in the E-Ti/CS, G-Ti/CS and G-Ti groups as compared to C-Ti (P<0.05). Coatings with collagen and CS appear to improve both the quantity and quality of bone formed around Ti implants in ovarectomized rats. A simultaneous ethinyl estradiol- and genistein-rich diet seems to enhance these effects.

Controlled Self-Coating of Implant Surfaces with Autologous Molecules

mplant fixation is correlated with direct bone apposition on the implant surface. In a former study it was reported that a new coating material enhances the bone-to-implant-contact in comparison to machined and rough surfaces. This study is aimed at clarifying the effect of an enhanced bone-to-implant-contact that is induced by a new coating material. The coating is produced by spin and spray coating and consists of a silica matrix, in which nanocrystalline hydroxyapatite is embedded. The coating material exhibits a high porosity in the micrometer and nanometer scale. Coated implants were inserted subcutaneously in Wistar Rats. The specimens were excised after 6 and 12 days. EDX and SEM analysis showed a reduction of the silica amount within 6 days. In accordance to former results of a bone grafting material with the same structure, this matrix change is responsible for an initial bone formation at early stages.

Model for direct bone apposition on pre-existing surfaces, during peri-implant osseointegration

In the present paper, a model for the early stages of peri-implant bone regeneration is developed. This model is able to capture some important characteristics of endosseous healing, which were not incorporated in the existing models. It is a well known fact, that during peri-implant osseointegration, bone forms only by apposition on the pre-existing rigid surface, which initially consists of the implant surface and the old bone surface. In order to track the movement of the front of the newly formed bone, a moving boundary problem is formulated. Another important feature of the current model, is that the cell differentiation is considered as a gradual process, evolving in time and being influenced by the presence of growth factors. Hence, the evolution of cell differentiation level is captured in the present approach. Numerical methods, used to solve the set of partial differential equations with hyperbolic terms, defined within the domain with the moving boundary, are described.

Evaluation of the in vitro cell-material interactions and in vivo osteo-integration of a spinal acrylic bone cement

Polymethylmethacrylate bone cements have proven performance in arthroplasty and represent a common bone filler, e.g. in vertebroplasty. However, acrylic cements are still subject to controversy concerning their exothermic reaction and osteo-integration potential. Therefore, we submitted a highly filled acrylic cement to a systematic investigation on the cell-material and tissue-implant response in vitro and in vivo. Cured Vertecem V+ Cements were characterized by electron microscopy. Human bone marrow-derived mesenchymal stem cell morphology, growth and differentiation on the cured cement were followed for 28 days in vitro. The uncured cement was injected in an ovine cancellous bone defect and analysed 4 and 26 weeks post-implantation. The rough surface of the cement allowed for good stem cells adhesion in vitro. Up-regulation of alkaline phosphatase was detected after 8 days of incubation. No adverse local effects were observed macroscopically and microscopically following 4 and 26 weeks of implantation of the cement into drill-hole defects in ovine distal femoral epiphysis. Direct bone apposition onto the implant surface was observed resulting in extended signs of osteo-integration over time (35.2 ± 24.2% and 88.8 ± 8.8% at week 4 and 26, respectively). Contrary to the established opinion concerning bony tissue response to implanted acrylic bone cements, we observed an early cell-implant in vitro interaction leading to cell growth and differentiation and significant signs of osteo-integration for this acrylic cement using standardized methods. Few outlined limitations, such as the use of low cement volumes, have to be considered in the interpretation of the study results.

Bone healing of commercial oral implants with RGD immobilization through electrodeposited poly(ethylene glycol) in rabbit cancellous bone

Immobilization of RGD peptides on titanium (Ti) surfaces enhances implant bone healing by promoting early osteoblastic cell attachment and subsequent differentiation by facilitating integrin binding. Our previous studies have demonstrated the efficacy of RGD peptide immobilization on Ti surfaces through the electrodeposition of poly(ethylene glycol) (PEG) (RGD/PEG/Ti), which exhibited good chemical stability and bonding. The RGD/PEG/Ti surface promoted differentiation and mineralization of pre-osteoblasts. This study investigated the in vivo bone healing capacity of the RGD/PEG/Ti surface for biomedical application as a more osteoconductive implant surface in dentistry. The RGD/PEG/Ti surface was produced on an osteoconductive implant surface, i.e. the grit blasted micro-rough surface of a commercial oral implant. The osteoconductivity of the RGD/PEG/Ti surface was compared by histomorphometric evaluation with an RGD peptide-coated surface obtained by simple adsorption in rabbit cancellous bone after 2 and 4weeks healing. The RGD/PEG/Ti implants displayed a high degree of direct bone apposition in cancellous bone and achieved greater active bone apposition, even in areas of poor surrounding bone. Significant increases in the bone to implant contact percentage were observed for RGD/PEG/Ti implants compared with RGD-coated Ti implants obtained by simple adsorption both after 2 and 4weeks healing (P<0.05). These results demonstrate that RGD peptide immobilization on a Ti surface through electrodeposited PEG may be an effective method for enhancing bone healing with commercial micro-rough surface oral implants in cancellous bone by achieving rapid bone apposition on the implant surface.

Increased bone apposition on a titanium oxide surface incorporating phosphate and strontium

This study investigated the osteoconductivity of titanium (Ti) implants with a phosphate (P)- and strontium (Sr) ion-incorporated oxide surface, produced by hydrothermal treatment in the rabbit cortical and cancellous bone, for future biomedical applications as a biocompatible endosseous implant surface. The P- and Sr ion-incorporated Ti implants (P/Sr implant) were produced by hydrothermal treatment using a P- and Sr-containing solution. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy and optical profilometry. Forty screw implants (20 control and 20 experimental) were placed in the tibiae and femoral condyles of 10 New Zealand White rabbits. The surface in vivo osteoconductivity of the P/Sr implants was compared with micro-arc oxidized (TO) implants with surface calcium and P chemistry by histomorphometric analysis in the cortical and cancellous bone after 4 weeks of implantation. The P/Sr implants showed moderately rough surface features and had lower R(a) values than the TO implants. Histologically, more direct bone apposition was observed on the surface of the P/Sr implants. The P/Sr implants displayed significantly higher bone-to-implant contact percentages compared with the TO implant in both the tibiae and the femoral condyles (P<0.01). The results indicate that the hydrothermally produced P- and Sr ion-incorporated Ti oxide surface may be effective in improving implant osseointegration in both cortical and cancellous bone by increasing bone apposition, due to its surface properties combining micro-topography, P/Sr chemistry and superior wettability.