Underlying mechanisms at the bone-biomaterial interface

Outcomes of Ulnar Shortening Osteotomy with an Intramedullary Bone Graft for Idiopathic Ulnar Impaction Syndrome

Background

Although several techniques for the treatment of ulnar impaction syndrome (UIS) have been introduced, there have still been reports on various complications such as delayed union, nonunion, refracture, wrist pain, plate irritation, and chronic regional pain syndrome. This study aimed to compare the differences in radiological and clinical outcomes of patients in which intramedullary bone grafting was performed in addition to plate stabilization with those without additional bone grafting during ulnar shortening osteotomies (USOs).

Methods

Between November 2014 and June 2021, 53 wrists of 50 patients with idiopathic UIS were retrospectively reviewed. Patients were divided into 2 groups according to whether intramedullary bone grafting was performed. Among the 53 wrists, USO with an intramedullary bone graft was performed in 21 wrists and USO without an intramedullary bone graft was performed in 32 wrists. Demographic data and factors potentially associated with bone union time were analyzed.

Results

There was no significant difference between the 2 groups when comparing postoperative radioulnar distance, postoperative ulnar variance, amount of ulnar shortening, and postoperative Disabilities of the Arm, Shoulder and Hand score. Compared to the without-intramedullary bone graft group, bone union time of the osteotomy site was significantly shortened, from 8.8 ± 3.0 weeks to 6.7 ± 1.3 weeks in the with-intramedullary bone graft group. Moreover, there were no cases of nonunion or plate-induced symptoms. Both in univariable and multivariable analyses, intramedullary bone grafting was associated with shorter bone union time.

Conclusions

USO with an intramedullary bone graft for idiopathic UIS has favorable radiological and clinical outcomes. The advantage of this technique is the significant shortening of bone union time.

Sterilization Procedures for Titanium Alloy Surfaces Leads to Higher Expression of Biofilm-Related Staphylococcus aureus Genes

Background: Around 1-2% of all implantation surgeries lead to implant-related infections, incurring costs of $40,000-$160,000 per total hip PJI. The 5-year mortality rate of prosthetic joint infections is up to 21%. To prevent infections during surgery, sterile surgery rooms and procedures have been developed and certified standards have been established. To guarantee the sterility, implants can be acquired already sterile from manufacturers. Some titanium implants can be delivered unsterilized with a manual for sterilization procedure in compliance with ISO 17664. The aim of this study is to evaluate if the most used sterilization methods (steam sterilization in an autoclave and UV light sterilization) of titanium alloys, can influence the biofilm forming capacity of Staphylococcus aureus. In this study, we examined the influence of sterilization methods on the gene expression of biofilm-associated genes and regulators. Methods: We compared gene expression of icaADBC, SarA, SigB, and SodA on titanium CP4 and Ti6Al4V alloys sterilized by UV-light and pressurized saturated steam sterilization. We performed RT-qPCR after RNA extraction of Staphylococcus aureus ATCC 29213. In addition, bacterial cell growth on the sterilized titanium surfaces was examined by colony forming unit counting on agar plates after 24 h of incubation. Results: Colony forming units of S. aureus on titanium CP4 samples showed a higher tendency in colony counts when sterilized with UV light than with pressurized saturated steam (autoclaved). Similarly, colony forming unit counts on Ti6Al4V samples showed tendencies of higher numbers on UV light sterilized samples than on autoclaved samples. Gene expression of icaADBC, SarA and SodA between steamed samples and UV light sterilized samples showed no difference on titanium CP4 samples, whereas SigB showed higher gene expression on titanium CP4 samples when sterilized with UV light than in an autoclave. On autoclaved Ti6Al4V samples, all examined genes showed 4 to 9 times higher fold changes in gene expression than on UV light sterilized samples. Conclusions: This study indicates that steam sterilization of Ti6Al4V can increase biofilm formation of S. aureus on its surface. The significantly increased gene expression of biofilm responsible genes may indicate a modification of titanium surfaces on alloy components. This may promote biofilm formation that can lead to implant-infections in vivo.

Surface Free Energy and Composition Changes and Ob Cellular Response to CHX-, PVPI-, and ClO2-Treated Titanium Implant Materials

The study evaluated the interaction of a titanium dental implant surface with three different antibacterial solutions: chlorhexidine, povidone-iodine, and chlorine dioxide. Implant surface decontamination is greatly challenging modern implant dentistry. Alongside mechanical cleaning, different antibacterial agents are widely used, though these could alter implant surface properties. Commercially pure (CP) grade 4 titanium (Ti) discs were treated with three different chemical agents (chlorhexidine 0.2% (CHX), povidone-iodine 10% (PVPI), chlorine dioxide 0.12% (ClO₂)) for 5 min. Contact angle measurements, X-ray photoelectron spectroscopy (XPS) analysis, and cell culture studies were performed. Attachment and proliferation of primary human osteoblast cells were investigated via MTT (dimethylthiazol-diphenyl tetrazolium bromide), alamarBlue, LDH (lactate dehydrogenase), and fluorescent assays. Contact angle measurements showed that PVPI-treated samples (Θ = 24.9 ± 4.1) gave no difference compared with controls (Θ = 24.6 ± 5.4), while CHX (Θ = 47.2 ± 4.1) and ClO₂ (Θ = 39.2 ± 9.8) treatments presented significantly higher Θ values. All samples remained in the hydrophilic region. XPS analysis revealed typical surface elements of CP grade 4 titanium (Ti, O, and C). Both MTT and alamarBlue cell viability assays showed similarity between treated and untreated control groups. The LDH test revealed no significant difference, and fluorescent staining confirmed these results. Although there was a difference in surface wettability, a high proliferation rate was observed in all treated groups. The in vitro study proved that CHX, PVPI, and ClO₂ are proper candidates as dental implant decontamination agents.

Dental Implants: Enhancing Biological Response Through Surface Modifications

Surface characteristics are an important factor for long-term clinical success of dental implants. Alterations of implant surface characteristics accelerate or improve osseointegration by interacting with the physiology of bone healing. Dental implant surfaces have been traditionally modified at the microlevel. Recently, researchers have actively investigated nano-modifications in dental implants. This review explores implant surface modifications that enhance biological response at the interface between a bone and the implant.

Calcium Orthophosphate (CaPO4)-Based Bioceramics: Preparation, Properties, and Applications

Various types of materials have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A short time later, such synthetic biomaterials were called bioceramics. Bioceramics can be prepared from diverse inorganic substances, but this review is limited to calcium orthophosphate (CaPO4)-based formulations only, due to its chemical similarity to mammalian bones and teeth. During the past 50 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the CaPO4-based implants would remain biologically stable once incorporated into the skeletal structure or whether they would be resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed, and such formulations became an integrated part of the tissue engineering approach. Now, CaPO4-based scaffolds are designed to induce bone formation and vascularization. These scaffolds are usually porous and harbor various biomolecules and/or cells. Therefore, current biomedical applications of CaPO4-based bioceramics include artificial bone grafts, bone augmentations, maxillofacial reconstruction, spinal fusion, and periodontal disease repairs, as well as bone fillers after tumor surgery. Prospective future applications comprise drug delivery and tissue engineering purposes because CaPO4 appear to be promising carriers of growth factors, bioactive peptides, and various types of cells.

Cell osteogenic bioactivity mediated precisely by varying scaled micro-pits on ordered micro/nano hierarchical structures of titanium

Hierarchical surface structures with micro–nano scale play a crucial role in regulation of cell proliferation and osteogenic differentiation. It has been proven that cells are extremely sensitive to the nanoscaled structure and show multifarious phenotypes. Though a vital function of microstructure on osseointegration has been confirmed, the cell performances response to different microscaled structure is needed to be further dissected and in depth understood. In this work, the ordered micro–nano hierarchical structures with varying micro-scaled pits were precisely fabricated on titanium successfully by the combination of electrochemical, chemical etching and anodization as well. In vitro systematical assessments indicated that the micro–nano multilevel structures on titanium exhibited excellent cells adhesion and spreading ability, as well as steerable proliferation and osteogenic differentiation behaviors. It is shown that smaller micro-pits and lower roughness of the hierarchical structures enabled faster cell propagation. Despite cell growth was delayed on micro–nano titanium with relatively larger cell-match-size micro-pits and roughness, osteogenic-specific genes were significantly elevated. Furthermore, the alkaline phosphatase activity, collagen secretion and extracellular matrix mineralization of MC3T3-E1 on multi-scaled titanium were suppressed by a large margin after adding IWP-2 (an inhibitor of Wnt/β-catenin signal pathway), indicating this pathway played a crucial part in cell osteogenic differentiation modulated by micro–nano structures.

Biocompatibility Assessment of Polylactic Acid (PLA) and Nanobioglass (n-BG) Nanocomposites for Biomedical Applications

Scaffolds based on biopolymers and nanomaterials with appropriate mechanical properties and high biocompatibility are desirable in tissue engineering. Therefore, polylactic acid (PLA) nanocomposites were prepared with ceramic nanobioglass (PLA/n-BGs) at 5 and 10 wt.%. Bioglass nanoparticles (n-BGs) were prepared using a sol–gel methodology with a size of ca. 24.87 ± 6.26 nm. In addition, they showed the ability to inhibit bacteria such as Escherichia coli (ATCC 11775), Vibrio parahaemolyticus (ATCC 17802), Staphylococcus aureus subsp. aureus (ATCC 55804), and Bacillus cereus (ATCC 13061) at concentrations of 20 w/v%. The analysis of the nanocomposite microstructures exhibited a heterogeneous sponge-like morphology. The mechanical properties showed that the addition of 5 wt.% n-BG increased the elastic modulus of PLA by ca. 91.3% (from 1.49 ± 0.44 to 2.85 ± 0.99 MPa) and influenced the resorption capacity, as shown by histological analyses in biomodels. The incorporation of n-BGs decreased the PLA crystallinity (from 7.1% to 4.98%) and increased the glass transition temperature (Tg) from 53 °C to 63 °C. In addition, the n-BGs increased the thermal stability due to the nanoparticle’s intercalation between the polymeric chains and the reduction in their movement. The histological implantation of the nanocomposites and the cell viability with HeLa cells higher than 80% demonstrated their biocompatibility character with a greater resorption capacity than PLA. These results show the potential of PLA/n-BGs nanocomposites for biomedical applications, especially for long healing processes such as bone tissue repair and avoiding microbial contamination.

Bioprinting of cell-laden hydrogels onto titanium alloy surfaces to produce a bioactive interface

The surface of metal implants serves as a powerful signaling cue for cells. Its properties play an essential role in stabilizing the bone-implant interface and facilitating the early osseointegration by encouraging bone deposition on the surface. However, effective strategies to deliver cells to the metal surfaces are yet to be explored. Here, we use a bioprinting process called reactive jet impingement (ReJI) to deposit high concentrations (4×10⁷  cells/mL) of mesenchymal stromal cells (MSCs) within hydrogel matrices directly onto the titanium alloy metal surfaces that vary in surface roughness and morphology. In this proof of concept study, we fabricate cell-hydrogel-metal systems with the aim of enhancing bioactivity through delivering MSCs in hydrogel matrices at the bone-implant interface. Our results show that the deposition of high cell concentrations encourages quick cell-biomaterial interactions at the hydrogel-metal surface interface, and cell morphology is influenced by the surface type. Cells migrate from the hydrogels and deposit mineralized matrix rich in calcium and phosphorus on the titanium alloy surfaces. We demonstrate that ReJI bioprinting is a promising tool to deliver cells in a three-dimensional (3D) environment before implantation that can be used when developing a new generation of medical devices for bone tissue engineering. This article is protected by copyright. All rights reserved.

Biomaterials as a Vital Frontier for Stem Cell-Based Tissue Regeneration

Biomaterials and tissue regeneration represent two fields of intense research and rapid advancement. Their combination allowed the utilization of the different characteristics of biomaterials to enhance the expansion of stem cells or their differentiation into various lineages. Furthermore, the use of biomaterials in tissue regeneration would help in the creation of larger tissue constructs that can allow for significant clinical application. Several studies investigated the role of one or more biomaterial on stem cell characteristics or their differentiation potential into a certain target. In order to achieve real advancement in the field of stem cell-based tissue regeneration, a careful analysis of the currently published information is critically needed. This review describes the fundamental description of biomaterials as well as their classification according to their source, bioactivity and different biological effects. The effect of different biomaterials on stem cell expansion and differentiation into the primarily studied lineages was further discussed. In conclusion, biomaterials should be considered as an essential component of stem cell differentiation strategies. An intense investigation is still required. Establishing a consortium of stem cell biologists and biomaterial developers would help in a systematic development of this field.

Surface Electric Fields Increase Human Osteoclast Resorption through Improved Wettability on Carbonate-Incorporated Apatite

Osteoclast-mediated bioresorption can be an efficient means of incorporating the dissolution of biomaterials in the bone remodeling process. Because of the compositionally and structurally close resemblance of biomaterials with the natural mineral phases of the bone matrix, synthetic carbonate-substituted apatite (CA) is considered as an ideal biomaterial for clinical use. The present study therefore investigated the effects of electrical polarization on the surface characteristics and interactions with human osteoclasts of hydroxyapatite (HA) and CA. Electrical polarization was found to improve the surface wettability of these materials by increasing the surface free energy, and this effect was maintained for 1 month. Analyses of human osteoclast cultures established that CA subjected to a polarization treatment enhanced osteoclast resorption but did not affect the early differentiation phase or the adherent morphology of the osteoclasts as evaluated by staining. These data suggest that the surface characteristics of the CA promoted osteoclast resorption. The results of this work are expected to contribute to the future design of cell-mediated bioresorbable biomaterials capable of resorption by osteoclasts and of serving as a scaffold for bone regeneration.

Microbially Catalyzed Biomaterials for Bone Regeneration

Bone is a complex mineralized tissue composed of various organic (proteins, cells) and inorganic (hydroxyapatite, calcium carbonate) substances with micro/nanoscale structures. To improve interfacial bioactivity of bone-implanted biomaterials, extensive efforts are being made to fabricate favorable biointerface via surface modification. Inspired by microbially catalyzed mineralization, a novel concept to biologically synthesize the micro/nanostructures on bioceramics, microbial-assisted catalysis, is presented. It involves three processes: bacterial adhesion on biomaterials, production of CO₃ ^2- assisted by bacteria, and nucleation and growth of CaCO₃ nanocrystals on the surface of bioceramics. The microbially catalyzed biominerals exhibit relatively uniform micro/nanostructures on the surface of both 2D and 3D α-CaSiO₃ bioceramics. The topographic and chemical cues of the grown micro/nanostructures present excellent in vitro and in vivo bone-forming bioactivity. The underlying mechanism is closely related to the activation of multiple biological processes associated with bone regeneration. The study offers a microbially catalytic concept and strategy of fabricating micro/nanostructured biomaterials for tissue regeneration.

Proteomic identification of serum proteins to induce osteoconductivity of hydroxyapatite

We performed proteomic analysis of rat serum proteins adsorbed on hydroxyapatite (HAp) and α-alumina (α-Al₂O₃) in order to identify proteins that specifically adsorb onto HAp and control cellular responses. Proteins with either or both molecular weight of 22-32 kDa and computed isoelectric point of 5.0-5.5 were preferentially adsorbed on HAp. In total, 182 proteins were adsorbed on both HAp and α-Al₂O₃, of which 14 were highly enriched on HAp, whereas 68 were adsorbed only on HAp. Therefore, 82 (14+68) proteins were further evaluated by bioinformatics and literature-based analyses. We predicted that hepatocyte growth factor and angiopoietin-like protein 3 (ANGPTL3) are candidate proteins responsible for the osteoconductivity of HAp. Although ANGPTL3 promoted the attachment and spreading of MC3T3-E1 cells, it did not promote their proliferation and differentiation. Our results suggest that specific adsorption of ANGPTL3 on HAp induced osteoconductivity by enhancing the attachment and spreading of osteoblasts.

Decellularized scaffold and its elicited immune response towards the host: the underlying mechanism and means of immunomodulatory modification

The immune response of the host towards a decellularized scaffold is complex. Not only can a number of immune cells influence this process, but also the characteristics, preparation and modification of the decellularized scaffold can significantly impact this reaction. Such factors can, together or alone, trigger immune cells to polarize towards either a pro-healing or pro-inflammatory direction. In this article, we have comprehensively reviewed factors which may influence the immune response of the host towards a decellularized scaffold, including the source of the biomaterial, biophysical properties or modifications of the scaffolds with bioactive peptides, drugs and cytokines. Furthermore, the underlying mechanism has also been recapitulated.

Assessment of implant surface and instrument insert changes due to instrumentation with different tips for ultrasonic-driven debridement

Background

To assess the changes of implant surfaces of different roughness after instrumentation with ultrasonic-driven scaler tips of different materials.

Methods

Experiments were performed on two moderately rough surfaces (I—Inicell® and II—SLA®), one surface without pre-treatment (III) and one smooth machined surface (IV). Scaler tips made of steel (A), PEEK (B), titanium (C), carbon (D) and resin (E) were used for instrumentation with a standardized pressure of 100 g for ten seconds and under continuous automatic motion. Each combination of scaler tip and implant surface was performed three times on 8 titanium discs. After instrumentation roughness was assessed by profilometry, morphological changes were assessed by scanning electron microscopy, and element distribution on the utmost surface by energy dispersive X-ray spectroscopy.

Results

The surface roughness of discs I and II were significantly reduced by instrumentation with all tips except E. For disc III and IV roughness was enhanced by tip A and C and, only for IV, by tip D. Instrumentation with tips B, D and E left extensive residuals on surface I, II and III. The element analysis of these deposits proved consistent with the elemental composition of the respective tip materials.

Conclusion

All ultrasonic instruments led to microscopic alterations of all types of implants surfaces assessed in the present study. The least change of implant surfaces might result from resin or carbon tips on machined surfaces.

Development of Robust Chitosan–Silica Class II Hybrid Coatings with Antimicrobial Properties for Titanium Implants

The purpose of this study was to develop robust class II organic–inorganic films as antibacterial coatings on titanium alloy (Ti6Al4V) implants. Coating materials were prepared from organic chitosan (20–80 wt.%) coupled by 3-glycydoxytrimethoxysilane (GPTMS) with inorganic tetraethoxysilane (TEOS). These hybrid networks were imbedded with antimicrobial silver nanoparticles (AgNPs) and coated onto polished and acid-etched Ti6Al4V substrates. Magic-angle spinning nuclear magnetic resonance (13CMAS-NMR), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and the ninhydrin assay, confirmed the presence and degree of covalent crosslinking (91%) between chitosan and GPTMS. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) identified surface roughness and microtopography on thin films and confirmed homogeneous distribution of elements throughout the coating. Cross-hatch and tensile adhesion testing demonstrated the robustness and adherence (15–20 MPa) of hybrid coatings to acid-etched titanium substrates. Staphylococcus aureus and Escherichia coli cultures and their biofilm formation were inhibited by all hybrid coatings. Antibacterial effects increased markedly for coatings loaded with AgNPs and appeared to increase with chitosan content in biofilm assays. These results are promising in the development of class II hybrid materials as robust and highly adherent antibacterial films on Ti6Al4V implants.

Layer-by-layer immobilizing of polydopamine-assisted ε-polylysine and gum Arabic on titanium: Tailoring of antibacterial and osteogenic properties

Bacterial infection has become a crucial reason that give rise to failure of medical implants in clinical applications. In this regard, various antibacterial surface modifications of implants have been developed in recent years. However, it remains a challenge to enable the implant surfaces with both suitable antibacterial and osteogenic properties. In this work, ε-polylysine and gum Arabic multilayer composite films were immobilized layer by layer (LBL) on anodized titanium with the assistance of polydopamine for the first time. In vitro antibacterial results showed that the bacteria numbers decreased with an increase in the loading amount of ε-polylysine. Furthermore, long-term antibacterial property up to 3 weeks against both gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) was obtained combined with the merits of covalent binding and LBL methods. Meanwhile, the cell proliferation and osteogenic differentiation of BMSCs on titanium dioxide nanotubes (TNTs) modified with composite films was significantly improved. Remarkably, a facile method to optimize anti-infective and osteogenic properties of medical titanium has been developed, and it was demonstrated that the ε-polylysine and gum Arabic multilayer composite films with assistance of polydopamine were able to endow the orthopedic implant materials both improved antibacterial property and excellent biocompatibility, which is of profound significance for practical application of titanium-based implants.

Surface Properties of Retrieved Cementless Femoral Hip Endoprostheses Produced from a Ti6Al7Nb Alloy

We have investigated new and retrieved cementless hip endoprostheses that prematurely failed due to (i) aseptic loosening, (ii) infection and (iii) latent infection. The aim was to better understand the physico-chemical phenomena on the surfaces and sub-surfaces of the Ti6Al7Nb alloy implant. The results of our studies should enable us to distinguish the causes of premature failure, optimize the surface modification, achieve optimal osseointegration and extend the useful lifetime of the implants. The surface properties of the Ti6Al7Nb alloys of the hip-stem endoprostheses (30 retrieved and 2 new) were determined by contact-angle measurements and the average surface roughness. The surface chemistry and microstructure were analysed by scanning electron microscopy (SEM) for morphology, energy-dispersive X-ray spectroscopy (EDS) for the chemistry, and electron back-scatter diffraction (EBSD) for the phase analysis; Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) for the surface chemistry; and electrochemical measurements for the corrosion. The improved wettability of the grit-blasted surface of the Ti6Al7Nb stems after autoclaving was measured, as was the super wettability after oxygen-plasma sterilization. The secondary-electron images showed that the morphology and microstructure of the new and retrieved stems (prematurely failed due to aseptic loosening, infection and latent infection) differ slightly, while the EDS analysis revealed corundum contamination of the grit-blasted surface. We found corundum-contaminated Ti6Al7Nb stem surfaces and sub-surfaces for all the investigated new and retrieved implants. These residues are a potential problem, i.e., third-body wear particles, and probably induce the osteolysis and aseptic loosening.

Tailoring Surface Hydrophilicity Property for Biomedical 316L and 304 Stainless Steels: A Special Perspective on Studying Osteoconductivity and Biocompatibility

Stainless steels used as metal implants in the medical field have been attracting intensive attention due to their advantages in mechanical properties, anticorrosion properties, and cost effectiveness. Good osteoconductivity, low toxicity, and low inflammatory reactions are essential to stainless steel implant in vivo. However, there are few cases about the surface modification performed for enhancing the corrosion resistance, and there are few researches on the relationship between the surface properties of stainless steel and osteoconductivity when used as implants. This study employed 316L and 304 stainless steel for surface modification including hydrothermal treatment after acid immersion and anodizing treatment, while the as-polished stainless steel was used as a control group. Anticorrosion properties, protein adsorption properties, osteoconductivity, and anti-inflammation property of these specimens were intensively investigated in vitro and in vivo. It was found that specimen subjected to hydrothermal treatment at 230 °C after immersion in 18 M H₂SO₄ had the lowest metal ions release, while the anodized specimen had the highest release of Fe and Cr due to corrosion. The protein adsorption amount of the specimens was positively related to the osteoconductivity, suggesting protein adsorption is the prerequisite for good osteoconductivity. The osteoconductivity decreased first and then increased with the increase in water contact angle (WCA) value. The specimen with the surface modified by hydrothermal treatment after acid immersion had the highest protein adsorption amount and the best osteoconductivity due to its superhydrophilicity property. The protein adsorption capacity and osteoconductivity for stainless steel tended to be the same as Ti alloys studied before, indicating the surface hydrophilicity property of the implanted metals was the dominant factor affecting the osteoconductivity. From an anti-inflammation perspective, the specimen with the surface modified by hydrothermal treatment after acid immersion also exhibited the lowest thickness of the fibrous capsule membrane from the in vivo tests, suggesting its advantageous biocompatibility. Thus, this research can provide new insight into the application of austenitic stainless steel for implanted material purposes.

Plasma Proteins at the Interface of Dental Implants Modulate Osteoblasts Focal Adhesions Expression and Cytoskeleton Organization

The host-material interface is a crucial relationship dictating the possibility of successful osseointegration in implant dentistry. The aim of the present study was to characterize the effects of plasma proteins pre-adsorption on the adhesion capacity of osteoblasts, which occurs immediately after implant insertion in vivo. After having pre-adsorbed human plasma proteins on a machined and microrough titanium surface, MC3T3-E1 osteoblasts adhesion was evaluated through crystal violet cell adhesion assay, immunofluorescence staining for cytoskeleton, focal adhesions and cell nuclei, and scanning electron microscopy. The pre-adsorbed protein layer markedly affected the adhesion rate of cells, as well as their morphology and the expression of focal contacts. Moreover, protein adsorption to the underlying titanium surface was found to be correlated to surface pre-wetting. Thus, the early adsorption of serum proteins to the interface of dental implants impacts cell adhesion in terms of strength and of focal adhesions expression.

Photo-activated implants: a triple-blinded, split-mouth, randomized controlled clinical trial on the resistance to removal torque at various healing intervals

OBJECTIVES

Hydrophilic implant surfaces promote faster osseointegration of dental implants with a higher bone-implant contact (BIC) rate. Animal and in vitro studies proved that ultraviolet (UV) irradiation of titanium implants regains hydrophilicity. Clinical impact is still unclear. The objective of this RCT was to assess the removal torque (RT) required to unfix a surface-treated implant (test group) versus the original surface implant (control group) performed at various points in time. The null hypothesis stated that test and control implants will show the same deliberation force at specific time points.

MATERIAL AND METHODS

One hundred eighty partially edentulous patients were randomly assigned to six groups. In single-stage surgery, each patient received one test and one control implant. In total, 180 test and 180 control implants were placed epicrestally. Test implants received a surface treatment with UV irradiation prior to insertion, in order to reduce carbon and enhance hydrophilicity and thus wettability. Maximum RT values for test and control implants were recorded with a torque measuring device at implant placement (T1), after 1 (group 1), 2 (group 2), 3 (group 3), 4 (group 4), 6 (group 5) (T2), and 8 weeks (group 6) of healing. Subsequently, implants were returned to their original position for the continuation of the healing process.

RESULTS

No implant was lost. Age, gender, smoking, implant position, and bone quality could be excluded as confounding factors because of the lack of statistical significance. At T2, RT values were higher for test implants compared with those for control implants, being statistically significant in groups 2, 3, 4, and 6 (p < 0.05).

CONCLUSIONS

Our data support rejection of the null hypothesis.

CLINICAL RELEVANCE

Photo-activation of the surface of titanium implants leads to higher resistance to RT forces compared with that of non-treated implants, indicating improved healing and implant stability especially in the early healing phase.

Laser-Based Hybrid Manufacturing of Endosseous Implants: Optimized Titanium Surfaces for Enhancing Osteogenic Differentiation of Human Mesenchymal Stem Cells

Additive manufacturing (AM) is becoming increasingly important in the orthopedic and dental sectors thanks to two major advantages: the possibility of custom manufacturing and the integration of complex structures. However, at smaller scales, surface conditions of AM products are not mastered. Numerous non-fused powder particles give rise to roughness values (Sa) greater than 10 μm, thus limiting biomedical applications since the surface roughness of, e.g., metal implants plays a major role in the quality and rate of osseointegration. In this study, an innovative hybrid machine combining AM and a femtosecond laser (FS) was used to obtain Ti6Al4V parts with biofunctional surfaces. During the manufacturing process, the FS laser beam "neatly" ablates the surface, leaving in its path nanostructures created by the laser/matter interaction. This step decreases the Sa from 11 to 4 μm and increases the surface wettability. The behavior of human mesenchymal stem cells was evaluated on these new AM+FS surfaces and compared with that on AM surfaces and also on polished surfaces. The number of cells attached 24 h after plating is equivalent on all surfaces, but cell spreading is higher on AM+FS surfaces compared with their AM counterparts. In the longer term (days 7 and 14), fibronectin and collagen synthesis increase on AM+FS surfaces as opposed to AM alone. Alkaline phosphatase activity, osteocalcin production, and mineralization, markers of osteogenic differentiation, are significantly lower on raw AM surfaces, whereas on the AM+FS specimens they display a level equivalent to that on the polished surface. Overall, these results indicate that using an FS laser beam during the fabrication of AM parts optimizes surface morphology to favor osteoblastic differentiation. This new hybrid machine could make it possible to produce AM implants with functional surfaces directly at the end of AM, thereby limiting their post-treatments.

Impacts of platelet-rich fibrin and platelet-rich plasma on primary osteoblast adhesion onto titanium implants in a bisphosphonate in vitro model

BACKGROUND

Osteoblast adhesion is a crucial step in osseointegration of dental implants and can be influenced by modification of implant surface or the addition of bioactive agents. Bisphosphonates affect bone turnover, attenuating bone healing in implants patients. PRP and PRF are sources of growth factors involved in osteoblast adhesion, improving subsequent bone healing. The aim of the study was to investigate the impacts of PRP and PRF on adhesion of bisphosphonate-pretreated osteoblasts on titanium implant surfaces using the cell-count wash assay, the MTT-assay as well as real-time-cell analyser assay and scanning electronic microscopy.

METHODS

Titanium implants were colonised for 24 hours with osteoblasts and zolendronic acid, PRP or PRF in different combinations. Afterwards, primary osteoblast adhesion was evaluated by counting the number of attached cells using a wash-assay cell analysis. Scanning electronic microscopy was performed and evaluated semi-quantitatively to assess the influence of the different groups on the ultrastructural cell morphology, such as cell size and shape as well as length and number of filopodia.

RESULTS

Zoledronic acid led to a decrease of osteoblast adherence onto implant surface. This effect was reversed by adding PRP or PRF. Scanning electronic microscopy showed that both PRP and PRF increased number and length of filopodia in adherent osteoblasts.

CONCLUSIONS

Zoledronic acid decreased osteoblast adhesion on implant surfaces, and PRF as well as PRP increased primary adhesion of zoledronic acid-treated osteoblasts on implant surfaces in vitro. Therefore, PRP and PRF may improve initial bone apposition and primary healing of dental implants in patients with bisphosphonate treatment.

Laser Surface Texturing of Alumina/Zirconia Composite Ceramics for Potential Use in Hip Joint Prosthesis

The use of metal shell to fix an acetabular cup to bone in hip joint prosthesis carries some limitations, including restrictions in prosthetic femur ball diameter and in patient’s range of motion. These drawbacks could be ideally overcome by using a monolithic ceramic acetabular cup, but the fixation of such an implant to host bone still remains a challenge. Since porous surfaces are known to promote more bone tissue interlocking compared to smooth materials, in this work the surfaces of sintered alumina/zirconia composite ceramics were treated by a pulsed laser radiation at 1064 nm with a pulse width in the nanosecond range, in order to impart controlled textural patterns. The influence of laser process parameters (e.g., energy per pulse, repetition rate, scanning speed, repetition number, angle of laser beam, and number of cycles) on the roughness and texture orientation was systematically investigated. The obtained surface topographies were inspected by optical and scanning electron microscopy, and the roughness was assessed by contact profilometry. Surface roughness could be modulated in the range of 3 to 30 µm by varying the processing parameters, among which the number of cycles was shown to play a major role. The laser treatment was also successfully adapted and applied to ceramic acetabular cups with a curved profile, thus demonstrating the feasibility of the proposed approach to process real prosthetic components.

Effect of Plasma Treatment of Titanium Surface on Biocompatibility

It was recently reported that implant osseointegration is affected by surface wettability. The relationship between hydrophilicity and cell adhesion was corroborated by numerous in vivo studies. Concentrated alkali improves the biocompatibility of pure titanium. Research was conducted on the mechanism by which this treatment increases hydrophilicity. In the present study, we used atmospheric pressure plasma processing to enhance the hydrophilicity of the material surface. The aim was to assess its influences on the initial adhesion of the material to rat bone marrow and subsequent differentiation into hard tissue. Superhydrophilicity was induced on a pure titanium surface with a piezobrush, a simple, compact alternative to the conventional atmospheric pressure plasma device. No structural change was confirmed by Scanning electron microscope (SEM) or scanning probe microscopy (SPM) observation. X-ray photoelectron spectroscopy (XPS) analysis presented with hydroxide formation and a reduction in the C peak. A decrease in contact angle was also observed. The treated samples had higher values for in vitro bovine serum albumin (BSA) adsorption, rat bone marrow (RBM) cell initial adhesion, alkaline phosphatase activity (ALP) activity tests, and factors related to bone differentiation than the untreated control. The present study indicated that the induction of superhydrophilicity in titanium via atmospheric pressure plasma treatment with a piezobrush affects RBM cell adhesion and bone differentiation without altering surface properties.

Titanium dioxide nanotubes of defined diameter enhance mesenchymal stem cell proliferation via JNK- and ERK-dependent up-regulation of fibroblast growth factor-2 by T lymphocytes

Long-term clinical success of a titanium implant not only depends upon osseointegration between implant and bone surface but also on the response of host immune cells. Following implantation of biomaterials, an inflammatory response, including T lymphocyte response, is ostensibly initiated by implant-cell interaction. However, little is known about the responses of T lymphocytes to titanium dioxide nanotubes. The present study aimed to explore the effect of titanium dioxide nanotubes on T lymphocytes in vitro and its biological consequences. The results of the present study showed that titanium dioxide nanotubes with diameter of 30-105 nm were non-cytotoxic to T lymphocytes, and the 105 nm titanium dioxide nanotube surface specifically possessed an ability to activate T lymphocytes, thus increasing DNA synthesis and cell proliferation. In addition, the 105 nm titanium dioxide nanotubes significantly activated the expression of FGF-2 gene and protein in T lymphocytes although smaller nanotubes (i.e. those with diameters of approximately 30 and 70 nm) had little effect on this. The present study investigated the mechanism by which 105 nm nanotubes stimulated FGF-2 expression in T lymphocytes by blocking key MAPK pathways. The inhibitors of JNK1/2/3 and ERK1/2 significantly inhibited 105 nm titanium dioxide nanotubes-induced FGF-2 expression. Corresponding to the increased expression of FGF-2, only the supernatant from T lymphocytes cultured on 105 nm nanotubes stimulated human mesenchymal stem cell proliferation. FGF-2 blocking antibody partially reversed the increased proliferation of human mesenchymal stem cells, supporting the role of T lymphocyte-derived FGF-2 in enhanced human mesenchymal stem cell proliferation. This suggests a significant role of T lymphocyte-titanium dioxide nanotube interaction in the proliferation of human mesenchymal stem cells, which is pivotal to the formation of new bone following implant placement.

Comparative study of DFDBA and FDBA block grafts in combination with chorion membrane for the treatment of periodontal intra-bony defects at 12 months post surgery

The goal of periodontal therapy is to prevent periodontal disease progression and to regenerate lost periodontal tissues. Various bone grafts are used alone or in combination with other treatment modalities for periodontal therapy. In literature no reports are presented with block allografts in the treatment of intrabony defects in periodontitis. Hence the study aimed to evaluate and compare clinically and radiographically freeze dried bone and demineralized freeze dried bone block allografts with chorion membrane in intra-bony defects at 12 months post-surgery. Eighteen intra-bony defects (9 intra patient pairs) in 9 patients with chronic periodontitis were randomly assigned to group 1 (FDBA + Chorion membrane) and group 2 (DFDBA + Chorion membrane) for periodontal therapy. Clinical and radiographic (RVG) measurements were made at base line and 12 months. Data obtained was subjected to statistical analysis. At 12 months on intra-group comparison both the groups showed statistically significant improvement in the plaque and gingival indices with reduction in the mobility, probing pocket depth and gain in clinical attachment (p value < 0.001). Radiographs showed significant bone fill and increased bone density (p value < 0.001). On inter-group comparison no statistical difference were observed at 12 months in clinical parameters and bone fill among both the groups. However, group 1 (FDBA) showed increase in the bone density which was statistically significant (p value < 0.001). The use of the FDBA and DFDBA block allografts showed significant improvement in the periodontal prognosis of teeth with intra-bony defects. Within the limitation of the present study, both the groups showed similar results with significant increase in bone density in FDBA group.

A critical review of multifunctional titanium surfaces: New frontiers for improving osseointegration and host response, avoiding bacteria contamination

Evolution of metal implants progressively shifted the focus from adequate mechanical strength to improved biocompatibility and absence of toxicity and, finally, to fast osseointegration. Recently, new frontiers and challenges of Ti implants have been addressed to improvement of bioactivity, fighting of bacterial infection and biofilm formation, as well as modulation of inflammation. This is closely related to the clinical demand of multifunctional implants able to simultaneously have a number of specific responses with respect to body fluids, cells (osteoblasts, fibroblasts, macrophages) and pathogenic agents (bacteria, viruses). This complex system of multiple biological stimuli and surface responses is a major arena of the current research on biomaterials and biosurfaces. This review covers the strategies explored to this purpose since 2010 in the case of Ti and Ti alloys, considering that the number of related papers doubled about in the last seven years and no review has comprehensively covered this engaging research area yet. The different approaches followed for producing multifunctional Ti-based surfaces involve the use of thick and thin inorganic coatings, chemical surface treatments, and functionalization strategies coupled with organic coatings.

STATEMENT OF SIGNIFICANCE

According to the clinical demand of multifunctional implants able to simultaneously have a number of specific responses with respect to body fluids, cells and pathogenic agents, new frontiers of Ti implants have been addressed to improvement of bioactivity, fighting of bacterial infection and biofilm formation, as well as modulation of inflammation. Literature since 2010 is here reviewed. Several strategies for getting bioactive and antibacterial actions on Ti surfaces have been suggested, but they still need to be optimized with respect to several concerns. A further step will be to combine on the same surface a proven ability of modulation of inflammatory response. The achievement of multifunctional surfaces able to modulate inflammation and to promote osteogenesis is a grand challenge.

Nanoscale Topographical Characterization of Orbital Implant Materials

The search for an ideal orbital implant is still ongoing in the field of ocular biomaterials. Major limitations of currently-available porous implants include the high cost along with a non-negligible risk of exposure and postoperative infection due to conjunctival abrasion. In the effort to develop better alternatives to the existing devices, two types of new glass-ceramic porous implants were fabricated by sponge replication, which is a relatively inexpensive method. Then, they were characterized by direct three-dimensional (3D) contact probe mapping in real space by means of atomic force microscopy in order to assess their surface micro- and nano-features, which were quantitatively compared to those of the most commonly-used orbital implants. These silicate glass-ceramic materials exhibit a surface roughness in the range of a few hundred nanometers (S_q within 500–700 nm) and topographical features comparable to those of clinically-used “gold-standard” alumina and polyethylene porous orbital implants. However, it was noted that both experimental and commercial non-porous implants were significantly smoother than all the porous ones. The results achieved in this work reveal that these porous glass-ceramic materials show promise for the intended application and encourage further investigation of their clinical suitability.

Influence of the wettability of different titanium surface topographies on initial cellular behavior

This study examined the influence of the time-dependent wettability of different surface topographies on initial cellular behavior. Titanium disks with smooth topography (SM) and three kinds of rough topography (sandblasted (SA), microtopography (M) and nanotopography (N)) were prepared. Time-dependent changes in surface wettability were observed in all surfaces as shown in previous studies. On SM surfaces, hydrophobic alteration influenced cell spreading and the activity of RhoA (a small GTPase protein of the Rho family), while no alterations were observed on rough surfaces except for the number of adherent cells. Serum adsorption could recover these functional deteriorations by hydrophobic alteration. These findings suggest that surface topography is a more potent regulator in initial cellular behaviors such as cell spreading and RhoA activation than surface wettability.

Patient-Specific Surgical Implants Made of 3D Printed PEEK: Material, Technology, and Scope of Surgical Application

Additive manufacturing (AM) is rapidly gaining acceptance in the healthcare sector. Three-dimensional (3D) virtual surgical planning, fabrication of anatomical models, and patient-specific implants (PSI) are well-established processes in the surgical fields. Polyetheretherketone (PEEK) has been used, mainly in the reconstructive surgeries as a reliable alternative to other alloplastic materials for the fabrication of PSI. Recently, it has become possible to fabricate PEEK PSI with Fused Filament Fabrication (FFF) technology. 3D printing of PEEK using FFF allows construction of almost any complex design geometry, which cannot be manufactured using other technologies. In this study, we fabricated various PEEK PSI by FFF 3D printer in an effort to check the feasibility of manufacturing PEEK with 3D printing. Based on these preliminary results, PEEK can be successfully used as an appropriate biomaterial to reconstruct the surgical defects in a “biomimetic” design.

Surface characteristics of dental implants: A review

OBJECTIVES

During the last decades, several changes of paradigm have modified our view on how biomaterials' surface characteristics influence the bioresponse. After becoming aware of the role of a certain microroughness for improved cellular contact and osseointegration of dental titanium implants, the likewise important role of surface energy and wettability was increasingly strengthened. Very recently, synergistic effects of nanoscaled topographical features and hydrophilicity at the implant/bone interface have been reported.

METHODS

Questions arise about which surface roughness and wetting data are capable to predict the bioresponse and, ultimately, the clinical performance. Current methods and approaches applied for topographical, wetting and surface energetic analyses are highlighted. Current knowledge of possible mechanisms explaining the influence of roughness and hydrophilicity at the biological interface is presented.

RESULTS

Most marketed and experimental surfaces are based on commonly available additive or subtractive surface modifying methods such as blasting, etching or anodizing. Different height, spatial, hybrid and functional roughness parameters have been identified as possible candidates able to predict the outcome at hard and soft tissue interfaces. Likewise, hydrophilic implants have been proven to improve the initial blood contact, to support the wound healing and thereby accelerating the osseointegration.

SIGNIFICANCE

There is clear relevance for the influence of topographical and wetting characteristics on a macromolecular and cellular level at endosseous implant/biosystem interfaces. However, we are still far away from designing sophisticated implant surfaces with the best possible, selective functionality for each specific tissue or cavity interface. Firstly, because our knowledge of the respective surface related reactions is at best fragmentary. Secondly, because manufacturing of multi-scaled complex surfaces including distinct nanotopographies, wetting properties, and stable cleanliness is still a technical challenge and far away from being reproducibly transferred to implant surfaces.

Biocompatibility of four common orthopedic biomaterials following neuroelectromyostimulation: An in-vivo study

Despite the worldwide high prevalence of total joint arthroplasty (TJA), life expectancy of prosthesis remains limited by mechanical and chemical constraint which promote wear debris production, surrounding tissues damage and finally prosthesis loosening. Such results could be amplified by neuro-myoelectrostimulation (NMES; widely used to reduce neuromuscular deficits observed following TJA surgery). It was previously described in an in vivo experiment that interactions between NMES and Ti6Al4V implant are deleterious for both implant and surrounding muscles. The purpose of the present study was to compare the biocompatibility of four common orthopedic biomaterials, two metallic (Ti6Al4V, CrCo) and two nonmetallic (PEEK, Al₂ O₃ ) alloys, fixed on rat tibial crest in which the surrounding muscles were electrostimulated. Muscle cell death rate was not found significantly increased, with or without electrical stimulation for nonmetallic implants. Contrary to Ti6Al4V alloy, the CrCo implant did not induce destruction of the surrounding muscle. However, cell viability decreased for both metallic alloys when NMES was applied but within a greater significant extent for Ti6Al4V implant. Otherwise, when NMES was applied, implant-to-bone adhesion significantly decreased for Ti6Al4V while no significant difference was found for PEEK, Al₂ O₃ , and CrCo. Statistical analyses reveal also a lesser adhesion strength for Ti6Al4V compared with CrCo when NMES was applied. Selecting the most suitable material in term of biocompatibility remains a major concern and non-metallic materials seems to be more appropriated in regard to electrical currents used for post TJA care. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1156-1164, 2018.

Heat Generation on Implant Surface During Abutment Preparation at Different Elapsed Time Intervals

PURPOSE

The purpose of this study was to evaluate heat generation at the implant surface caused by abutment preparation using a diamond bur in a high-speed dental turbine in vitro at 2 different water-coolant temperatures.

MATERIALS AND METHODS

Thirty-two titanium-alloy abutments were connected to a titanium-alloy implant embedded in an acrylic resin placed within a water bath at a controlled temperature of 37°C. The specimens were equally distributed into 2 groups (16 each). Group 1: the temperature was maintained at 20 ± 1°C; and group 2: the temperature was maintained at 32 ± 1°C. Each abutment was prepared in the axial plane for 1 minute and in the occlusal plane for 1 minute. The temperature of the heat generated from abutment preparation was recorded and measured at 3 distinct time intervals.

RESULTS

Water-coolant temperature (20°C vs 32°C) had a statistically significant effect on the implant's temperature change during preparation of the abutment (P < 0.0001).

CONCLUSION

The use of water-coolant temperature of 20 ± 1°C during preparation of the implant abutment decreased the temperature recorded at the implant surface to 34.46°C, whereas the coolant temperature of 32 ± 1°C increased the implant surface temperature to 40.94°C.

Nanoplasmonic Sensing at the Carbon-Bio Interface: Study of Protein Adsorption at Graphitic and Hydrogenated Carbon Surfaces

Various forms of carbon are known to perform well as biomaterials in a variety of applications and an improved understanding of their interactions with biomolecules, cells, and tissues is of interest for improving and tailoring their performance. Nanoplasmonic sensing (NPS) has emerged as a powerful technique for studying the thermodynamics and kinetics of interfacial reactions. In this work, the in situ adsorption of two proteins, bovine serum albumin and fibrinogen, were studied at carbon surfaces with differing chemical and optical properties using nanoplasmonic sensors. The carbon material was deposited as a thin film onto NPS surfaces consisting of 100 nm Au nanodisks with a localized plasmon absorption peak in the visible region. Carbon films were fully characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and spectroscopic ellipsometry. Two types of material were investigated: amorphous carbon (a-C), with high graphitic content and high optical absorptivity, and hydrogenated amorphous carbon (a-C:H), with low graphitic content and high optical transparency. The optical response of the Au/carbon NPS elements was modeled using the finite difference time domain (FDTD) method, yielding simulated analytical sensitivities that compare well with those observed experimentally at the two carbon surfaces. Protein adsorption was investigated on a-C and a-C:H, and the protein layer thicknesses were obtained from FDTD simulations of the expected response, yielding values in the 1.8-3.3 nm range. A comparison of the results at a-C and a-C:H indicates that in both cases fibrinogen layers are thicker than those formed by albumin by up to 80%.

Acid etching of glass-infiltrated zirconia and its biological response

PURPOSE

The purpose of this study was to evaluate the influence of acid etching treatment on surface characteristics and biological response of glass-infiltrated zirconia.

MATERIALS AND METHODS

A hundred zirconia specimens were divided into four groups depending on surface treatments: untreated zirconia (group Z); acid-etched zirconia (group ZE); glass-infiltrated zirconia (group ZG); and glass-infiltrated and acid-etched zirconia (group ZGE). Surface roughness, surface topography, surface morphology, and Vickers hardness of specimens were evaluated. For biological response test, MC3T3-E1 cell attachment and proliferation on surface of the specimens were examined. The data were statistically analyzed using one-way ANOVA and Tukey's HSD test at a significance level of 0.05.

RESULTS

Group ZGE showed the highest surface roughness (Ra = 1.54 µm) compared with other groups (P < .05). Meanwhile, the hardness of group Z was significantly higher than those of other groups (P < .05). Cell attachment and cell proliferation were significantly higher in group ZGE (P < .05).

CONCLUSION

We concluded that effective surface roughness on zirconia could be made by acid etching treatment after glass infiltration. This surface showed significantly enhanced osteoblast cell response.

Cellular Response of Human Bone Marrow Derived Mesenchymal Stem Cells to Titanium Surfaces Implanted with Calcium and Magnesium Ions

Surface characteristics and cellular response to titanium surfaces that had been implanted with calcium and magnesium ions using plasma immersion ion implantation and deposition (PIIID) were evaluated. Three different titanium surfaces were analyzed: a resorbable blast media (RBM) surface (blasted with hydroxyapatite grit), a calcium ion-implanted surface, and a magnesium ion-implanted surface. The surface characteristics were investigated by scanning electron microscopy (SEM), surface roughness testing, X-ray diffraction (XRD), and Auger electron spectroscopy (AES). Human bone marrow derived mesenchymal stem cells were cultured on the 3 different surfaces. Initial cell attachment was evaluated by SEM, and cell proliferation was determined using MTT assay. Real-time polymerase chain reaction (PCR) was used to quantify osteoblastic gene expression (i.e., genes encoding RUNX2, type I collagen, alkaline phosphatase, and osteocalcin). Surface analysis did not reveal any changes in surface topography after ion implantation. AES revealed that magnesium ions were present in deeper layers than calcium ions. The calcium ion- and magnesium ion-implanted surfaces showed greater initial cell attachment. Investigation of cell proliferation revealed no significant difference among the groups. After 6 days of cultivation, the expression of RUNX2 was higher in the magnesium ion-implanted surface and the expression of osteocalcin was lower in the calcium ion-implanted surface. In conclusion, ion implantation using the PIIID technique changed the surface chemistry without changing the topography. Calcium ion- and magnesium ion-implanted surfaces showed greater initial cellular attachment.

Calcium Phosphate Bioceramics: A Review of Their History, Structure, Properties, Coating Technologies and Biomedical Applications

Calcium phosphate (CaP) bioceramics are widely used in the field of bone regeneration, both in orthopedics and in dentistry, due to their good biocompatibility, osseointegration and osteoconduction. The aim of this article is to review the history, structure, properties and clinical applications of these materials, whether they are in the form of bone cements, paste, scaffolds, or coatings. Major analytical techniques for characterization of CaPs, in vitro and in vivo tests, and the requirements of the US Food and Drug Administration (FDA) and international standards from CaP coatings on orthopedic and dental endosseous implants, are also summarized, along with the possible effect of sterilization on these materials. CaP coating technologies are summarized, with a focus on electrochemical processes. Theories on the formation of transient precursor phases in biomineralization, the dissolution and reprecipitation as bone of CaPs are discussed. A wide variety of CaPs are presented, from the individual phases to nano-CaP, biphasic and triphasic CaP formulations, composite CaP coatings and cements, functionally graded materials (FGMs), and antibacterial CaPs. We conclude by foreseeing the future of CaPs.

Alumina-fluorapatite composite coating deposited by atmospheric plasma spraying: An agent of cohesion between bone and prostheses

In order to remedy the poor biological and tribological properties of 316L stainless steel (SS), plasma sprayed bio-ceramic coatings have been widely investigated. In the present study, a small amount of fluorapatite (Fap) was introduced into alumina in order to enhance its bioactivity. The powder feedstock was sprayed on 316L substrate by Atmospheric Plasma Spraying (APS) technology. The roughness profiles and average roughness values were determined using 3D profilometry. The cross sectional morphologies of the coatings were examined by scanning electron microscopy (SEM). Adhesive strength, micro-hardness and tribological properties were also examined. Experimental results revealed that Al₂O₃/Fap coating showed a good microhardness property revealing that the calcium aluminates were quite effective in improving the Fap mechanical behavior. The tribological characteristics of both alumina and alumina-Fap coating were also compared to those of classical hydroxyapatite (Hap) coatings as reported in the literature. The main finding of this work was that Fap coating can contribute to the cohesion between bone and prostheses and thus ensure a more durable and reliable prostheses.

Digital light procession three-dimensional printing acrylate/collagen composite airway stent for tracheomalacia

Recently, more and more researchers have focused on airway stent applied in tracheomalacia. The airway stents for clinical application were usually manufactured in accordance with a fixed pattern, which were difficult to perfect match with children, especially infants. Digital light procession of light curing acrylate resin implantation showed higher accuracy and printing speed over traditional three-dimensional printing techniques. In this article, a novel personalized airway stent was developed by digital light procession three-dimensional printing and was modified by collagen I extracted from the fish scales. The morphology of the collagen-modified airway stent was examined by scanning electron microscopy, and the chemical structures were examined by attenuated total internal reflectance Fourier transform infrared spectroscopy. The biocompatibility of this synthetic acrylate/collagen composite airway stent was characterized by water contact angle test and cell culture. The results confirmed that the composite airway stent was hydrophilic and non-cytotoxic toward a cultured human bronchial epithelial cell line with good cell viability and show excellent physicochemical and biological properties. In conclusion, this study presented the three-dimensional printing composite acrylate and collagen airway stent may have potential in customized treatment for tracheomalacia.

Comparison of osteogenic potential of poly-ether-ether-ketone with titanium-coated poly-ether-ether-ketone and titanium-blended poly-ether-ether-ketone: An in vitro study

STATEMENT OF PROBLEM

Poly-ether-ether-ketone (PEEK), a high-performance semi-crystalline thermoplastic polymer, has been employed to replace the metallic implant components in orthopedics. There were various studies performed in accordance to medical grade PEEK, but the relationship between titanium dioxide (TiO₂)-coated PEEK, TiO₂-blended PEEK, and untreated PEEK still remains complicated, even undefined.

PURPOSE

The purpose of this study was to compare and quantify the osteogenic potential of untreated PEEK, TiO₂-coated PEEK and TiO₂-blended PEEK.

MATERIALS AND METHODS

Three groups with ten samples in each group were designed for this study. They were Group 1 - Untreated PEEK, Group 2 - TiO₂-coated PEEK, Group 3 - TiO₂-blended PEEK. The PEEK samples were prepared according to the ISO standard 15309:2013 and milled to size of 15 mm × 2 mm, and the surfaces were finished with grit-blasted alumina of size 20 μm. In this 10 samples were chosen for Group 1. Group 2 samples were prepared by coating TiO₂ nanoparticles by arc ion plating, and Group 3 samples were prepared by blending TiO₂ nanoparticles in HAAKE rheocord with degree of blending analyzed by torque rheometer. These samples were tested for cytotoxicity using human osteosarcoma cells, and alkaline phosphatase (ALP) activity was performed to evaluate and quantify the bone mineralization process. The cross-sectional and the fracture morphology of coatings was observed by a field emission scanning electron microscope (SEM) with the magnification range ×20-×200,000.

RESULT

Results of cytotoxicity assay and ALP assay of Group 1, Group 2, and Group 3 were statistically analyzed. SEM analysis result clearly showed the difference in the matrix before and after cell adhesion.

CONCLUSION

The results made it evident that n-TiO₂-coated PEEK was more versatile biomaterial of choice in implant dentistry followed by n-TiO₂-blended PEEK and untreated PEEK.

Mechanically tuned nanocomposite coating on titanium metal with integrated properties of biofilm inhibition, cell proliferation, and sustained drug delivery

The clinical success of coated implants in executing biological functions inclusive of sustainable drug release and long term antibacterial activity without antibiotics is critical. To this aim, a nanohybrid of silver nanoparticles (AgNPs) cored in polyvinyl alcohol nanocapsules (Ag-PVA NCs) embedded in chitosan (CS) matrix loaded with anti-inflammatory drug naproxen was prepared. The synthesized nanohybrids that were subjected to coatings on (3-aminopropyl)triethoxysilane (APTES) treated titanium (Ti) metal exhibited dual role of excellent inhibition on biofilm formation and sustained drug release. These dual characteristics are achieved mainly based on intrinsic antibacterial property of AgNPs and differential entrapment of drug in PVA polymeric shell of AgNPs and CS matrix. The coatings also demonstrated enhanced mechanical properties with increasing inorganic filler and stress shielding on Ti metal. The biocompatibility tests involving adhesion, proliferation and differentiation of osteoblast cells demonstrated the efficacy of Ag-PVA NCs embedded in CS matrix as a suitable coating material for orthopedic applications.