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

Atomic Force Microscopy: An Introduction

Imaging of nano-sized particles and sample features is crucial in a variety of research fields, for instance, in biological sciences, where it is paramount to investigate structures at the single particle level. Often, two-dimensional images are not sufficient, and further information such as topography and mechanical properties are required. Furthermore, to increase the biological relevance, it is desired to perform the imaging in close to physiological environments. Atomic force microscopy (AFM) meets these demands in an all-in-one instrument. It provides high-resolution images including surface height information leading to three-dimensional information on sample morphology. AFM can be operated both in air and in buffer solutions. Moreover, it has the capacity to determine protein and membrane material properties via the force spectroscopy mode. Here we discuss the principles of AFM operation and provide examples of how biomolecules can be studied. New developments in AFM are discussed, and by including approaches such as bimodal AFM and high-speed AFM (HS-AFM), we show how AFM can be used to study a variety of static and dynamic single biomolecules and biomolecular assemblies.

Influence of Topography and Composition of Commercial Titanium Dental Implants on Cell Adhesion of Human Gingiva-Derived Mesenchymal Stem Cells: An In Vitro Study

The topography and composition of dental implant surfaces directly impact mesenchymal cell adhesion, proliferation, and differentiation, crucial aspects of achieving osseointegration. However, cell adhesion to biomaterials is considered a key step that drives cell proliferation and differentiation. The aim of this study was to characterize characterize the topography and composition of commercial titanium dental implants manufactured with different surface treatments (two sandblasted/acid-etched (SLA) (INNO Implants, Busan, Republic of Korea; BioHorizonsTM, Oceanside, CA, USA) and two calcium phosphate (CaP) treated (Biounite®, Berazategui, Argentina; Zimmer Biomet, Inc., Warsaw, IN, USA)) and to investigate their influence on the process of cell adhesion in vitro. A smooth surface implant (Zimmer Biomet, Inc.) was used as a control. For that, high-resolution methodologies such as scanning electron microscopy (SEM), X-ray dispersive spectroscopy (EDX), laser scanning confocal microscopy (LSCM), and atomic force microscopy (AFM) were employed. Protein adsorption and retromolar gingival mesenchymal stem cells (GMSCs) adhesion to the implant surfaces were evaluated after 48 h. The adherent cells were examined by SEM and LSCM for morphologic and quantitative analyses. ANOVA and Tukey tests (α = 0.05) were employed to determine statistical significance. SEM revealed that INNO, BioHorizonsTM, and Zimmer implants have an irregular surface, whereas Biounite® has a regular topography consisting of an ordered pattern. EDX confirmed a calcium and phosphate layer on the Biounite® and Zimmer surfaces, and AFM exhibited different roughness parameters. Protein adsorption and cell adhesion were detected on all the implant surfaces studied. However, the Biounite® implant with CaP and regular topography showed the highest protein adsorption capacity and density of adherent GMSCs. Although the Zimmer implant also had a CaP treatment, protein and cell adhesion levels were lower than those observed with Biounite®. Our findings indicated that the surface regularity of the implants is a more determinant factor in the cell adhesion process than the CaP treatment. A regular, nanostructured, hydrophilic, and moderately rough topography generates a higher protein adsorption capacity and thus promotes more efficient cell adhesion.

Histological and Histomorphometric Comparison of Innovative Dental Implants Laser Obtained: Animal Pilot Study

OBJECTIVE

Evaluation of the in vivo bone response of two innovative titanium surfaces ytterbium laser active fiber obtained (L1-L2) compared to a sandblasted and acid etched (SBAE) during early phase of osseointegration.

MATERIAL AND METHODS

Three implant groups with the same macroscopic features were obtained (L1-L2-SBAE) to promote specific surface characteristics. Scanning electron microscopy, profilometric evaluation, X-ray spectrometry, and diffraction analysis were performed. For each group, six implants were placed in the tibiae of three Peli Buey sheep, and histologic, histomorphometric analysis, bone to implant contact (BIC), and the Dynamic Osseointegration index (DOI) were performed.

RESULTS

During the early phases of osseointegration, the histological and histomorphometric results showed significant differences between L1-L2-SBAE implants. At 15 and 30 days, histological analysis detected a newly bone formation around all specimens with an higher vital bone in L2 compared to L1 and SBAE both in cortical and in poor-quality marrow bone. At same time, histomorphometric analysis showed significantly higher BIC values in L2 (42.1 ± 2.6 and 82.4 ± 2.2) compared to L1 (5.2 ± 3.1 and 56.2 ± 1.3) and SBAE (23.3 ± 3.9 and 77.3 ± 0.4). DOI medium value showed a higher rate in L2 (2.83) compared to SBAE (2.60) and L1 (1.91).

CONCLUSIONS

With the limitations of this pilot study, it is possible to assess that the titanium surface characteristics, and not the technologies used to obtain the modification, played a crucial role during the osseointegration process. Histological, histomorphometric, BIC, and DOI evaluation showed a significantly higher rate in L2 specimens compared to others, confirming that the implant surface could increase the bone response in cortical or marrow poor quality bone during the initial phases of osseointegration.

The osteogenesis performance of titanium modified via plasma-enhanced chemical vapor deposition: in vitro and in vivo studies

Titanium (Ti) and its alloys are widely used in dental implants due to their favorable mechanical properties and biocompatibility. Surface characteristics, including physical and chemical properties, are crucial factors to enhance the osteogenesis performance of Ti. The aim of this study is to evaluate amino group surface modification to facilitate the osteogenic potential and bone repair of dental implants both in vitro and in vivo. Herein, amino group-modified Ti surfaces were constructed via the plasma-enhanced chemical vapor deposition (PECVD) technique with an allylamine monomer. The adhesion, proliferation, alkaline phosphate activity and osteogenesis-related genetic expression of MG-63 cells on the surfaces were performed in vitro and presented a significant increase in amino group-modified Ti compared with that in Ti. The in vivo study in miniature pigs was evaluated through micro-computed tomography analysis and histological evaluation, which exhibited enhanced new bone formation in amino group-modified Ti compared with that in Ti after implantation for 4, 8 and 12 weeks. Consequently, amino group surface modification with the PECVD technique may provide a promising modification method to enhance the osteogenesis performance of Ti implants.

In vivo effect of UV-photofunctionalization of CoCrMo in processes of guided bone regeneration and tissue engineering

Photofunctionalization of implant materials with ultraviolet (UV) radiation have been subject of study in the last two decades, and previous research on CoCrMo discs have showed good results in terms of bioactivity and the findings of apatite-like crystals in vitro. In the current study, CoCrMo domes were photofunctionalized with UV radiation of 254 nm on their internal faces during 24 hr; they were implanted in rabbit tibia and remained for 3, 4, and 6 weeks. The potential to induce bone formation beneath the dome-shaped membranes was evaluated through morphometric, histologic, and density measurements; and the results were compared with those obtained under control untreated domes. Higher density values were observed for irradiated domes at 3 weeks, whereas higher volumes were obtained under photofunctionalized domes for longer periods (4 and 6 weeks). Histologically, woven bone was formed by endochondral ossification in all cases; differences in the architecture and size of the trabeculae and in the number of osteoblasts were noted between irradiated and non-irradiated samples. The UV radiation of 254 nm generated a larger bone volume fraction compared to that found in the absence of UVC radiation and induced an increase of density in the early stages of healing, leading to a better initial bone quality and improved osseointegration.

Effect of different surface treatments on the shear bond strength of luting cements used with implant-supported prosthesis: An in vitro study

PURPOSE

The aim of this study was to investigate the shear bond strength of luting cements used with implant retained restorations on to titanium specimens after different surface treatments.

MATERIALS AND METHODS

One hundred twenty disc shaped specimens were used. They were divided into three groups considering the surface treatments (no treatment, sandblasting, and oxygen plasma treatment). Water contact angle of specimens were determined. The specimens were further divided into four subgroups (n=10) according to applied cement types: polycarboxylate cement (Adhesor Carbofine-AC), temporary zinc oxide free cement (Temporary Cement-ZOC), non eugenol provisional cement for implant retained prosthesis (Premier Implant Cement-PI), and non eugenol acrylic-urethane polymer based provisional cement for implant luting (Cem Implant Cement-CI). Shear bond strength values were evaluated. Two-way ANOVA test and Regression analysis were used to statistical analyze the results.

RESULTS

Overall shear bond strength values of luting cements defined in sandblasting groups were considerably higher than other surfaces (P<.05). The cements can be ranked as AC > CI > PI > ZOC according to shear bond strength values for all surface treatment groups (P<.05). Water contact angles of surface treatments (control, sandblasting, and plasma treatment group) were 76.17° ± 3.99, 110.45° ± 1.41, and 73.80° ± 4.79, respectively. Regression analysis revealed that correlation between the contact angle of different surfaces and shear bond strength was not strong (P>.05).

CONCLUSION

The retentive strength findings of all luting cements were higher in sandblasting and oxygen plasma groups than in control groups. Oxygen plasma treatment can improve the adhesion ability of titanium surfaces without any mechanical damage to titanium structure.

Biomimetic polyetheretherketone microcarriers with specific surface topography and self-secreted extracellular matrix for large-scale cell expansion

Reusable microcarriers with appropriate surface topography, mechanical properties, as well as biological modification through decellularization facilitating repeated cell culture are crucial for tissue engineering applications. Herein, we report the preparation of topological polyetheretherketone (PEEK) microcarriers via gas-driven and solvent exchange method followed by hydrothermal treatment at high temperature and pressure. After hydrothermal treated for 8 h, the resulting topological PEEK microcarriers exhibit walnut-like surface topography and good sphericity as well as uniform size distribution of 350.24 ± 19.44 µm. And the average width between ravine-patterned surface of PEEK microcarriers is 780 ± 290 nm. After repeated steam sterilization by autoclaving for three times, topological PEEK microcarriers show nearly identical results compared with previous ones indicating strong tolerance to high temperature and pressure. This is a unique advantage for large-scale cell expansion and clinical applications. Moreover, PEEK microcarriers with special topography possess higher protein adsorption efficiency. In addition, the reutilization and biofunctionalization with repeated decellularization of topological PEEK microcarriers show highly beneficial for cell adhesion and proliferation. Therefore, our study is of great importance for new generation microcarriers with micro-and nano-scale surface feature for a broad application prospect in tissue engineering.

Covalently-Linked Hyaluronan versus Acid Etched Titanium Dental Implants: A Crossover RCT in Humans

Biochemical modification of titanium surfaces (BMTiS) entails immobilization of biomolecules to implant surfaces in order to induce specific host responses. This crossover randomized clinical trial assesses clinical success and marginal bone resorption of dental implants bearing a surface molecular layer of covalently-linked hyaluronan in comparison with control implants up to 36 months after loading. Patients requiring bilateral implant rehabilitation received hyaluronan covered implants in one side of the mouth and traditional implants in the other side. Two months after the first surgery, a second surgery was undergone to uncover the screw and to place a healing abutment. After two weeks, the operator proceeded with prosthetic procedures. Implants were evaluated by periapical radiographs and the crestal bone level was recorded at mesial and distal sites—at baseline and up to 36 months. One hundred and six implants were positioned, 52 HY-coated, and 48 controls were followed up. No differences were observed in terms of insertion and stability, wound healing, implant success, and crestal bone resorption at any time considered. All interventions had an optimal healing, and no adverse events were recorded. This trial shows, for the first time, a successful use in humans of biochemical-modified implants in routine clinical practice and in healthy patients and tissues with satisfactory outcomes.

Superficial Characteristics of Titanium after Treatment of Chorreated Surface, Passive Acid, and Decontamination with Argon Plasma

(1) Background. Titanium is characterized by its biocompatibility, resistance to maximum stress, and fatigue and non-toxicity. The composition, surface structure, and roughness of titanium have a key and direct influence on the osseointegration processes when it is used in the form of dental implants. The objective of the present study is to characterize, at chemical, superficial, and biological levels, the result of the application of the sandblasted with large-grit and acid-etched (SLA) treatment consisting of coarse-grained and double-passivated acid blasting with subsequent decontamination with argon plasma on the surface of titanium implants type IV. (2) Methods. Four Oxtein^® dental implants (Zaragoza, Spain) were investigated with the following coding: Code L63713T (titanium grade IV, 3.75 mm in diameter, and 13 mm in length). The surface of the implants was SLA type obtained from coarse-grained, double passivated acid, and decontaminated with argon plasma. The samples were in their sealed packages and were opened in our laboratory. The X-ray photoelectron spectroscopy (XPS) technique was used to characterize the chemical composition of the surface, and the scanning electronic microscope (SEM) technique was used to perform topographic surface evaluation. Cell cultures were also performed on both surfaces. (3) Results. The superficial chemical analysis of the studied samples presented the following components, approximately, expressed in atomic percentage: O: 39%; Ti: 18%; C: 39%; N: 2%; and Si: 1%. In the same way, the topographic analysis values were obtained in the evaluated roughness parameters: R_a: 1.5 μm ± 0.02%; R_q: 1.31 μm ± 0.33; R_z: 8.98 μm ± 0.73; R_p: 5.12 μm ± 0.48; R_v: 3.76 μm ± 0.51; and R_c: 4.92 μm ± 0.24. At a biological level, the expression of osteocalcin was higher (p < 0.05) on the micro-rough surface compared to that machined at 48 and 96 h of culture. (4) Conclusions. The data obtained in our study indicate that the total carbon content, the relative concentration of titanium, and the roughness of the treatment performed on the implants are in agreement with those found in the literature. Further, the roughness of the treatment performed on the implants throws a spongy, three-dimensional surface suitable for bone growth on it. The biological results found are compatible with the clinical use of the surface tested.

Enhancement of the biocompatibility by surface nitriding of a low-modulus titanium alloy for dental implant applications

To enhance their longevity, dental implants must be highly biocompatible and must have a low elastic modulus close to that of the bone. They must also possess a high superficial hardness and a high corrosion resistance. For these reasons, a recently developed low-modulus Ti-27Nb alloy with nontoxic elements was treated by gas nitriding at high temperature in this study. A very thin nitrided layer of 0.5 μm in thickness followed by an enriched nitrogen zone was observed. Consequently, a very high hardness evaluated at about 1800 HV was obtained in surface, which represents an increase of 4-5 times the hardness of the non-nitrided alloy. This superficial hardness was experimentally observed to decrease up to 800 nm in depth from the surface to the core. The low modulus of Ti-27Nb (evaluated at 55 GPa, which is twice lower than the commercially pure titanium) was not affected by the surface nitriding treatment. A better corrosion resistance was observed and a significant decrease in ion release rates for the nitrided alloy (ion release of 1.41 ng/cm² compared to the 163.58 ng/cm² obtained for the commercially pure titanium at pH = 7.48 in artificial Carter-Brugirard saliva). The cytocompatibility was not compromised and the cell viability performed on human osteoblasts, fibroblastic cells, and epithelial cells was enhanced on the nitrided surface in comparison with the non-nitrided surface. These combined properties make the nitrided Ti-27Nb alloy a good candidate for dental implant applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1483-1490, 2019.

Atomic Force Microscopy: An Introduction

Imaging of nano-sized particles and sample features is crucial in a variety of research fields. For instance in biological sciences, where it is paramount to investigate structures at the single particle level. Often two-dimensional images are not sufficient and further information such as topography and mechanical properties are required. Furthermore, to increase the biological relevance, it is desired to perform the imaging in close to physiological environments. Atomic force microscopy (AFM) meets these demands in an all-in-one instrument. It provides high-resolution images including surface height information leading to three-dimensional information on sample morphology. AFM can be operated both in air and in buffer solutions. Moreover, it has the capacity to determine protein and membrane material properties via the force spectroscopy mode. Here we discuss the principles of AFM operation and provide examples of how biomolecules can be studied. By including new approaches such as high-speed AFM (HS-AFM) we show how AFM can be used to study a variety of static and dynamic single biomolecules and biomolecular assemblies.

Improvement of Cr-Co-Mo Membrane Surface Used as Barrier for Bone Regeneration through UV Photofunctionalization: An In Vitro Study

Although there are several studies of the ultraviolet (UV) light-mediated photofunctionalization of titanium for use as implant material, the underlying mechanism is not fully understood. However, the results of in vitro and in vivo studies are very encouraging. The use of UV photofunctionalization as a surface treatment on other implant materials, as the Cr-Co-Mo alloy, has not been explored in depth. Using sandblasted Cr-Co-Mo discs, the surface photofunctionalization was studied for ultraviolet A (UVA, 365 nm) and ultraviolet C (UVC, 254 nm), and the surfaces were evaluated for their ability to sustain hydroxyapatite crystal growth through incubation in simulated body fluid for a seven-day period. The variation of the pre- and post-irradiation contact angle and surface composition was determined through the quantification of the weight percentage of Ca and P crystals by the EDAX ZAF method (EDS). Statistically significant differences (p < 0.05) were found for samples irradiated with UVA over 48 h, corresponding with hydrophilic surfaces, and the same result was found for samples exposed to 3 h of UVC. Superhydrophilic surfaces were found in samples irradiated for 12, 24 and 48 h with UVC. The decrease in the carbon content is related with the increase in the surface content of Ca and P, and vice versa over the Cr-Co-Mo surfaces.

Enhanced osteoblast adhesion on amino-functionalized titanium surfaces through combined plasma enhanced chemical vapor deposition (PECVD) method

A combined PECVD method has been developed to introduce amino-groups onto titanium implants for the better improvement of osseointegration.

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.

Titanium-Nitride Coating of Orthopaedic Implants: A Review of the Literature

Surfaces of medical implants can be enhanced with the favorable properties of titanium-nitride (TiN). In a review of English medical literature, the effects of TiN-coating on orthopaedic implant material in preclinical studies were identified and the influence of these effects on the clinical outcome of TiN-coated orthopaedic implants was explored. The TiN-coating has a positive effect on the biocompatibility and tribological properties of implant surfaces; however, there are several reports of third body wear due to delamination, increased ultrahigh molecular weight polyethylene wear, and cohesive failure of the TiN-coating. This might be due to the coating process. The TiN-coating process should be optimized and standardized for titanium alloy articulating surfaces. The clinical benefit of TiN-coating of CoCrMo knee implant surfaces should be further investigated.

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.

Direct metal laser sintering titanium dental implants: a review of the current literature

Statement of Problem. Direct metal laser sintering (DMLS) is a technology that allows fabrication of complex-shaped objects from powder-based materials, according to a three-dimensional (3D) computer model. With DMLS, it is possible to fabricate titanium dental implants with an inherently porous surface, a key property required of implantation devices. Objective. The aim of this review was to evaluate the evidence for the reliability of DMLS titanium dental implants and their clinical and histologic/histomorphometric outcomes, as well as their mechanical properties. Materials and Methods. Electronic database searches were performed. Inclusion criteria were clinical and radiographic studies, histologic/histomorphometric studies in humans and animals, mechanical evaluations, and in vitro cell culture studies on DMLS titanium implants. Meta-analysis could be performed only for randomized controlled trials (RCTs); to evaluate the methodological quality of observational human studies, the Newcastle-Ottawa scale (NOS) was used. Results. Twenty-seven studies were included in this review. No RCTs were found, and meta-analysis could not be performed. The outcomes of observational human studies were assessed using the NOS: these studies showed medium methodological quality. Conclusions. Several studies have demonstrated the potential for the use of DMLS titanium implants. However, further studies that demonstrate the benefits of DMLS implants over conventional implants are needed.