Surface modification of 316L stainless steel with magnetron sputtered TiN/VN nanoscale multilayers for bio implant applications

Evaluation of Biocompatibility of 316 L Stainless Steels Coated with TiN, TiCN, and Ti-DLC Films

In this study, TiN, TiCN, and Ti-diamond-like carbon (Ti-DLC) films were coated on 316 L stainless steel (AISI 316 L) substrate surface by physical vapor deposition. The biocompatibility of the three films (TiN, TiCN, and Ti-DLC) and three metals (AISI 316 L, Ti, and Cu) was compared on the basis of the differences in the surface morphology, water contact angle measurements, CCK-8 experiment results, and flow cytometry test findings. The biocompatibility of the TiN and TiCN films is similar to that of AISI 316 L, which has good biocompatibility. However, the biocompatibility of the Ti-DLC films is relatively poor, which is mainly due to the inferior hydrophobicity and large amount of sp2 phases. The presence of TiC nanoclusters on the surface of the Ti-DLC film aggravates the inferior biocompatibility. Compared to the positive Cu control group, the Ti-DLC film had a higher cell proliferation rate and lower cell apoptosis rate. Although the Ti-DLC film inhibited cell survival to a certain extent, it did not show obvious cytotoxicity. TiN and TiCN displayed excellent performance in promoting cell proliferation and reducing cytotoxicity; thus, TiN and TiCN can be considered good orthodontic materials, whereas Ti-DLC films require further improvement.

Microbial Biofilm Decontamination on Dental Implant Surfaces: A Mini Review

Introduction

After insertion into the bone, implants osseointegrate, which is required for their long-term success. However, inflammation and infection around the implants may lead to implant failure leading to peri-implantitis and loss of supporting bone, which may eventually lead to failure of implant. Surface chemistry of the implant and lack of cleanliness on the part of the patient are related to peri-implantitis. The only way to get rid of this infection is decontamination of dental implants.

Objective

This systematic review intended to study decontamination of microbial biofilm methods on titanium implant surfaces used in dentistry.

Methods

The electronic databases Springer Link, Science Direct, and PubMed were explored from their inception until December 2020 to identify relevant studies. Studies included had to evaluate the efficiency of new strategies either to prevent formation of biofilm or to treat matured biofilm on dental implant surfaces.

Results and Discussion

In this systematic review, 17 different groups of decontamination methods were summarized from 116 studies. The decontamination methods included coating materials, mechanical cleaning, laser treatment, photodynamic therapy, air polishing, anodizing treatment, radiation, sonication, thermal treatment, ultrasound treatment, chemical treatment, electrochemical treatment, antimicrobial drugs, argon treatment, and probiotics.

Conclusion

The findings suggest that most of the decontamination methods were effective in preventing the formation of biofilm and in decontaminating established biofilm on dental implants. This narrative review provides a summary of methods for future research in the development of new dental implants and decontamination techniques.

Manufacturing and Characterization of Zn-WC as Potential Biodegradable Material

This work presents the manufacturing and characterization of zinc-tungsten carbide (Zn-WC) nanocomposite as a potential biodegradable material. A highly homogeneous WC nanoparticle dispersion in a Zn matrix was achieved by molten salt assisted stir casting followed with hot rolling. The Vickers microhardness and ultimate tensile strength of zinc were enhanced more than 50% and 87%, respectively, with the incorporation of up to 4.4 vol. % WC nanoparticles. Additionally, Zn-WC nanocomposite retained high ductility (> 65%). However, the electrical and thermal conductivities were reduced by 12% and 21%, respectively. The significant enhancement in mechanical strength makes nanoparticle-reinforced zinc a promising candidate material for biodegradable metallic implants for a wide range of clinical applications, including orthopaedic and cardiovascular implants as well as bioresorbable electronics.

An Innovative Approach to Manganese-Substituted Hydroxyapatite Coating on Zinc Oxide⁻Coated 316L SS for Implant Application

In this paper, the synthesis of porous manganese substituted hydroxyapatite (Mn-HAp) coating on zinc oxide (ZnO) coated stainless steel (316L SS) using the electrodeposition technique is reported. The structural, functional, morphological, and elemental analyses are characterized by various analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Results of electrochemical techniques such as cyclic polarization and impedance show that the Mn-HAp coating on ZnO coated 316L SS has the highest corrosion resistance in simulated body fluid (SBF) solution. Moreover, dissolution of metal ions was extremely reduced, as evaluated by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The adhesion and hardness of Mn-HAp/ZnO bilayer coatings have superior mechanical properties over individual coatings. Further, the biocompatibility of in vitro osteoblast attachment, cell viability, and live/dead assessment also confirmed the suitability of Mn-HAp/ZnO bilayer coating on 316L SS for orthopedic applications.

Biocompatibility evaluation of sputtered zirconium-based thin film metallic glass-coated steels

Thin film metallic glasses comprised of Zr48Cu36Al8Ag8 (at.%) of approximately 1.5 μm and 3 μm in thickness were prepared using magnetron sputtering onto medical grade 316L stainless steel. Their structural and mechanical properties, in vitro corrosion, and antimicrobial activity were analyzed. The amorphous thin film metallic glasses consisted of a single glassy phase, with an absence of any detectable peaks corresponding to crystalline phases. Elemental composition close to the target alloy was noted from EDAX analysis of the thin film. The surface morphology of the film showed a smooth surface on scanning electron microscopy and atomic force microscopy. In vitro electrochemical corrosion studies indicated that the zirconium-based metallic glass could withstand body fluid, showing superior resistance to corrosion and electrochemical stability. Interactions between the coated surface and bacteria were investigated by agar diffusion, solution suspension, and wet interfacial contact methods. The results indicated a clear zone of inhibition against the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, confirming the antimicrobial activity of the thin film metallic glasses. Cytotoxicity studies using L929 fibroblast cells showed these coatings to be noncytotoxic in nature.