TiNOx coatings on roughened titanium and CoCr alloy accelerate early osseointegration of dental implants in minipigs

Dental implants in large animal models with experimental systemic diseases: A systematic review

This systematic review aims to identify and discuss the most used methodologies in pre-clinical studies for the evaluation of the implementation of dental implants in systemically compromised pigs and sheep. This study provides support and guidance for future research, as well as for the prevention of unnecessary animal wastage and sacrifice. Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) was used as a guideline; electronic searches were performed in PubMed, Scopus, Scielo, Web of Science, Embase, Science Direct, Brazilian Bibliography of Dentistry, Latin American and Caribbean Literature in Health Sciences, Directory of Open Access Journals, Database of Abstracts of Reviews of Effects, and gray literature until January 2022 (PROSPERO/CRD42021270119). Sixty-eight articles were chosen from the 2439 results. Most studies were conducted in pigs, mainly the Göttinger and Domesticus breeds. Healthy animals with implants installed in the jaws were predominant among the pig studies. Of the studies evaluating the effect of systemic diseases on osseointegration, 42% were performed in osteoporotic sheep, 32% in diabetic sheep, and 26% in diabetic pigs. Osteoporosis was primarily induced by bilateral ovariectomy and mainly assessed by X-ray densitometry. Diabetes was induced predominantly by intravenous streptozotocin and was confirmed by blood glucose analysis. Histological and histomorphometric analyses were the most frequently employed in the evaluation of osseointegration. The animal models presented unique methodologies for each species in the studies that evaluated dental implants in the context of systemic diseases. Understanding the most commonly used techniques will help methodological choices and the performance of future studies in implantology.

Advances in Multifunctional Bioactive Coatings for Metallic Bone Implants

To fix the bone in orthopedics, it is almost always necessary to use implants. Metals provide the needed physical and mechanical properties for load-bearing applications. Although widely used as biomedical materials for the replacement of hard tissue, metallic implants still confront challenges, among which the foremost is their low biocompatibility. Some of them also suffer from excessive wear, low corrosion resistance, infections and shielding stress. To address these issues, various coatings have been applied to enhance their in vitro and in vivo performance. When merged with the beneficial properties of various bio-ceramic or polymer coatings remarkable bioactive, osteogenic, antibacterial, or biodegradable composite implants can be created. In this review, bioactive and high-performance coatings for metallic bone implants are systematically reviewed and their biocompatibility is discussed. Updates in coating materials and formulations for metallic implants, as well as their production routes, have been provided. The ways of improving the bioactive coating performance by incorporating bioactive moieties such as growth factors, osteogenic factors, immunomodulatory factors, antibiotics, or other drugs that are locally released in a controlled manner have also been addressed.

Improved Biological Responses of Titanium Coating Using Laser-Aided Direct Metal Fabrication on SUS316L Stainless Steel

Direct metal fabrication (DMF) coatings have the advantage of a more uniform porous structure and superior mechanical properties compared to coatings provided by other methods. We applied pure titanium metal powders to SUS316L stainless steel using laser-aided DMF coating technology with 3D printing. The purpose of this study was to determine the efficacy of this surface modification of stainless steel. The capacity of cells to adhere to DMF-coated SUS316L stainless steel was compared with machined SUS316L stainless steel in vitro and in vivo. Morphological in vitro response to human osteoblast cell lines was evaluated using scanning electron microscopy. Separate specimens were inserted into the medulla of distal femurs of rabbits for in vivo study. The distal femurs were harvested after 3 months, and were then subjected to push-out test and histomorphometrical analyses. The DMF group exhibited a distinct surface chemical composition, showing higher peaks of titanium compared to the machined stainless steel. The surface of the DMF group had a more distinct porous structure, which showed more extensive coverage with lamellipodia from osteoblasts than the machined surface. In the in vivo test, the DMF group showed better results than the machined group in the push-out test (3.39 vs. 1.35 MPa, respectively, p = 0.001). In the histomorphometric analyses, the mean bone-to-implant contact percentage of the DMF group was about 1.5 times greater than that of the machined group (65.4 ± 7.1% vs. 41.9 ± 5.6%, respectively; p < 0.001). The porous titanium coating on SUS316L stainless steel produced using DMF with 3D printing showed better surface characteristics and biomechanical properties than the machined SUS316L.

Niobium-oxynitride coatings for biomedical applications: Its antibacterial effects and in-vitro cytotoxicity

316L Stainless Steel (SS) has been widely used in many medical applications, such as orthopedic prostheses and cardiovascular implants due to its good mechanical properties and resistance to corrosion. Despite its superior features, SS has bio-functionality problems. In this study, niobium oxynitride coatings were deposited onto 316L SS substrates to improve their biocompatibility using a reactive radio frequency (RF) magnetron sputtering technique. The nitrogen flow was fixed, and the nitrogen to oxygen flow ratio was set to 2, 5 and 10 to investigate the effect of oxygen concentration on biocompatibility and the antibacterial behavior of the oxynitride films. The microstructure, morphology and wettability properties of the coatings were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and an optical tensiometer. The antibacterial activities of coated and uncoated 316L substrates were tested against S. aureus and E. coli bacterial strains. The cytotoxic effects of NbO_xN_y-coated and uncoated substrates were evaluated on human fibroblast cells. The results showed that niobium oxynitride coatings were not cytotoxic and exhibited more antibacterial activity in comparison to the uncoated ones.

The Galvanic Effect of Titanium and Amalgam in the Oral Environment

The effects of the presence of amalgam on titanium (Ti) dissolution in the oral environment under acidic, neutral, and basic conditions was studied. The presence of amalgam was found to suppress Ti release under acidic conditions due to the redeposition of TiO_x/SnO_x on the surface of the Ti. The redeposition of SnO_x was due to the amalgam releasing its components (Hg, Cu, Sn, Ag) and the thermodynamic preference of Sn to oxidize, which was confirmed using mass measurements, ICP-MS analyses, and X-ray Photoelectron Spectroscopy (XPS). XPS depth profiling was performed to characterize the composition and oxidation states of the redeposited SnO_x/TiO_x film. Under basic conditions, the amalgam hindered Ti dissolution, but no redeposition of amalgam components was observed for the Ti.

A Review of In-Situ Grown Nanocomposite Coatings for Titanium Alloy Implants

Composite coatings are commonly applied to medical metal implants in order to improve biocompatibility and/or bioactivity. In this context, two types of titanium-based composite coatings have been reviewed as biocompatible and anti-bacterial coatings. The different composites can be synthesised on the surface of titanium using various methods, which have their own advantages and disadvantages. Moving with the smart and nanotechnology, multifunctional nanocomposite coatings have been introduced on implants and scaffolds for tissue engineering with the aim of providing more than one properties when required. In this context, titanium dioxide (TiO2) nanotubes have been shown to enhance the properties of titanium-based implants as part of nanocomposite coatings.

Titanium Powder Coating Using Metal 3D Printing: A Novel Coating Technology for Cobalt-Chromium Alloy Implants

Background

Three-dimensional (3D) printing with a direct metal fabrication (DMF) technology has been innovatively introduced in the field of surface treatment of prostheses. The purpose of this study was to determine whether such modifications on the surface of cobalt-chromium (CoCr) alloy by titanium powder coating using DMF improves the osseointegration ability of CoCr alloy.

Methods

We compared the in vitro and in vivo ability of cells to adhere to DMF-coated CoCr alloy with machining. Biological and morphological responses to human osteoblast cell lines were examined by measuring cell proliferation rate and observing expression of actin filament. For in vivo study, we inserted different specimens in each medulla of the distal femurs of rabbit. After 3 months, the distal femurs were harvested, and a push-out test and histomorphometric analyses were performed.

Results

The cell proliferation rate and cell adhesion in the DMF group were higher compared with those in the machined group. Human osteoblast cells on the DMF-coated surface were more strongly adhered and well-proliferated compared with those on the other surface. In the in vivo test, there was a significant difference in the ultimate shear strength between the DMF and machined groups (2.49 MPa vs. 0.87 MPa, respectively, p = 0.001). In the histomorphometric analysis, there was a significant difference in the mean bone-to-implant contact percentages between the DMF and machined groups (72.3 ± 6.2% vs. 47.6 ± 6.9%, respectively, p < 0.001).

Conclusion

Titanium coating of CoCr alloy with 3D metal printing provides optimal surface characteristics and a good biological surface both in vitro and in vivo.

CAD/CAM milled complete removable dental prostheses: An in vitro evaluation of biocompatibility, mechanical properties, and surface roughness

This study compared the biocompatibility, mechanical properties, and surface roughness of a pre-polymerized polymethyl methacrylate (PMMA) resin for CAD/CAM complete removable dental prostheses (CRDPs) and a traditional heat-polymerized PMMA resin. Two groups of resin substrates [Control (RC): conventional PMMA; Test (RA): CAD/CAM PMMA] were fabricated. Human primary osteoblasts and mouse embryonic-fibroblasts were cultured for biocompatibility assays. Mechanical properties and surface roughness were compared. ANOVA revealed no difference between the resin groups in the biocompatibility assays. RA demonstrated a higher elastic modulus (p=0.002), young's modulus (p=0.002), plastic energy (p=0.002), ultimate strength (p=0.0004), yield point (p=0.016), strain at yield point (p=0.037), and toughness (p<0.0001); while RC displayed a higher elastic energy (p<0.0001). Laser profilometry concluded a rougher surface profile (p<0.0001) for RA. This study concluded that the tested CAD/CAM resin was equally biocompatible and presented with improved mechanical properties than the traditional heat-polymerized PMMA resin used in the fabrication of CRDPs.

The synergistic effect of strontium-substituted hydroxyapatite and microRNA-21 on improving bone remodeling and osseointegration

Surgical failure, mainly caused by loosening implants, causes great mental and physical trauma to patients.

TiN x O y coatings facilitate the initial adhesion of osteoblasts to create a suitable environment for their proliferation and the recruitment of endothelial cells

Titanium-nitride-oxide coatings (TiN _x O _y ) improve osseointegration of endosseous implants. The exact mechanisms by which these effects are mediated are poorly understood except for an increase of osteoblast proliferation while a high degree of differentiation is maintained. One hypothesis holds that TiN _x O _y facilitates the initial spreading and adhesion of the osteoblasts. The aim of this work was to investigate the molecular mechanisms of osteoblast adhesion on TiN _x O _y as compared to microrough titanium SLA. A global view of the osseointegrative process, that is, taking into account other cell groups, especially endothelial cells, is also presented. To this aim, gene expression and focal adhesion analysis, cocultures and wound assays were performed early after seeding, from 6 h to 3 days. We demonstrated that TiN _x O _y coatings enhance osteoblast adhesion and spreading when compared to the standard microrough titanium. The integrin β1, either in association with α1 or with α2 plays a central role in these mechanisms. TiN _x O _y coatings optimize the process of osseointegration by acting at several levels, especially by upregulating osteoblast adhesion and proliferation, but also by supporting neovascularization and the development of a suitable inflammatory environment.

Modulation of osteoblast behavior on TiNxOy coatings by altering the N/O stoichiometry while maintaining a high thrombogenic potential

INTRODUCTION

Titanium nitride oxide (TiNxOy) coatings are known to stimulate osteoblast proliferation and osseointegration when compared to microrough titanium implants. The objectives of the present study were to determine whether the beneficial effects of TiNxOy coatings observed with implant osseointegration are dependent on N/O stoichiometry, with the final goal of optimizing these benefits. MMS: TiNxOy coatings with various N/O compositions were deposited on microrough titanium plates (Ti-SLA, 11 × 11 mm). Human primary osteoblast (hOBs) proliferation and gene expression were analyzed for a time course of three weeks, with or without additional stimulation by 1.25 (OH)2 vitamin D3 100 nM. Platelet adhesion/activation and thrombin generation were also assessed.

RESULTS

hOBs proliferation gradually increased with the amount of oxygen contained in the coatings. The effect was observed from day 7 to reach a maximum at day 10, with a 1.8 fold increase for the best coating as compared to Ti-SLA. SEM views indicated that cells adhered, spread and elongated faster on oxygen-rich TiNxOy films, while the differentiation process as well as the thombogenic potential was not affected.

CONCLUSIONS

The effect of TiNxOy coatings on osteoblast is dependent on their chemical composition; it increases with the amount of oxygen. TiNxOy coatings may act as a catalyst for cell-adhesion and proliferation early after seeding. In contrast, thrombogenicity of Ti-SLA surface is not affected by TiNxOy application.

Bone tissue response to plasma-nitrided titanium implant surfaces

A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration.

Mesenchymal stem cell response to topographically modified CoCrMo

Surface roughness on implant materials has been shown to be highly influential on the behavior of osteogenic cells. Four surface topographies were engineered on cobalt chromium molybdenum (CoCrMo) in order to examine this influence on human mesenchymal stem cells (MSC). These treatments were smooth polished (SMO), acid etched (AE) using HCl 7.4% and H₂SO₄ 76% followed by HNO₃ 30%, sand blasted, and acid etched using either 50 μm Al₂O₃ (SLA50) or 250 μm Al₂O₃ grit (SLA250). Characterization of the surfaces included energy dispersive X‐ray analysis (EDX), contact angle, and surface roughness analysis. Human MSCs were cultured onto the four CoCrMo substrates and markers of cell attachment, retention, proliferation, cytotoxicity, and osteogenic differentiation were studied. Residual aluminum was observed on both SLA surfaces although this appeared to be more widely spread on SLA50, whilst SLA250 was shown to have the roughest topography with an R_a value greater than 1 μm. All substrates were shown to be largely non‐cytotoxic although both SLA surfaces were shown to reduce cell attachment, whilst SLA50 also delayed cell proliferation. In contrast, SLA250 stimulated a good rate of proliferation resulting in the largest cell population by day 21. In addition, SLA250 stimulated enhanced cell retention, calcium deposition, and hydroxyapatite formation compared to SMO (p < 0.05). The enhanced response stimulated by SLA250 surface modification may prove advantageous for increasing the bioactivity of implants formed of CoCrMo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3747–3756, 2015.

Preparation and properties of plasma electrolytic oxidation coating on sandblasted pure titanium by a combination treatment

Plasma electrolytic oxidation (PEO) is one of the most applicable methods to produce bioceramic coating on a dental implant and sandblasting is a primary technique to modify metal surface properties. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by PEO technique to improve its bioactive performance. The time-dependent modified surfaces are characterized in terms of their microstructure, phase, chemical composition, mechanical properties and bioactivities. The results show that the combination-treated coating exhibits better properties than the PEO-treated one, especially in bioactivities, as evidenced by the HA formation after immersion in simulated body fluid (SBF) for 5 days and the cell viability after seeding for 1 or 3 days. The enhancement of the modified surface is attributed to a combination of the mechanical sandblasting and the microplasma oxidation.

Bone response to surface-modified titanium implants: studies on the early tissue response to implants with different surface characteristics

In a series of experimental studies, the bone formation around systematically modified titanium implants is analyzed. In the present study, three different surface modifications were prepared and evaluated. Glow-discharge cleaning and oxidizing resulted in a highly stoichiometric TiO₂ surface, while a glow-discharge treatment in nitrogen gas resulted in implants with essentially a surface of titanium nitride, covered with a very thin titanium oxide. Finally, hydrogen peroxide treatment of implants resulted in an almost stoichiometric TiO₂, rich in hydroxyl groups on the surface. Machined commercially pure titanium implants served as controls. Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy revealed no significant differences in oxide thickness or surface roughness parameters, but differences in the surface chemical composition and apparent topography were observed. After surface preparation, the implants were inserted in cortical bone of rabbits and evaluated after 1, 3, and 6 weeks. Light microscopic evaluation of the tissue response showed that all implants were in contact with bone and had a large proportion of newly formed bone within the threads after 6 weeks. There were no morphological differences between the four groups. Our study shows that a high degree of bone contact and bone formation can be achieved with titanium implants of different surface composition and topography.