In Vitro Biocompatibility of a New Titanium-29Niobium-13Tantalum-4.6Zirconium Alloy With Osteoblast-Like MG63 Cells

Biological Evaluation of Zinc Phosphate Cement for Potential Bone Contact Applications

Zinc phosphate cement is used in dentistry to lute crowns and bridges. So far, its biocompatibility for other applications has not been studied. This paper reports the biocompatibility of zinc phosphate towards MG63 cells, testing both the material (discs; 3 mm diameter × 1 mm thick) and leachate from the cement. Cell viability was determined using an MTT assay, and cytotoxicity from the effects of leachate, studied in triplicate. Microscopy (optical and scanning electron) determined the morphology and proliferation of cells attached to zinc phosphate. ICP-OES measured element release into leachate, and anti-microbial behaviour was determined against Streptococcus pyrogenes cultured on a Brain Heart Infusion agar using cement discs (3 mm diameter × 1 mm thick). Zones of inhibition were measured after 72 h. MG63 cells proliferated on zinc phosphate surfaces and retained their morphology. The cells were healthy and viable as shown by an MTT assay, both on cement and in leachate. High levels of phosphorus but low levels of zinc were released into leachate. The cement showed minimal antimicrobial activity against S. pyogenes, probably due to the long maturation times used. Zinc phosphate cement was found to be biocompatible towards MG63 cells, which indicates that it may be capable of use in bone contact applications.

In Vitro Molecular Study of Titanium-Niobium Alloy Biocompatibility

Titanium dental implants have common clinical applications due to their biocompatibility, biophysical and biochemical characteristics. Although current titanium is thought to be safe and beneficial for patients, there are several indications that it may release toxic metal ions or metal nanoparticles from its alloys into the surrounding environment, which could lead to clinically relevant complications including toxic reactions as well as immune dysfunctions. Hence, an adequate selection and testing of medical biomaterial with outstanding properties are warranted. This study was designed to explore the biocompatibility of smooth titanium-niobium alloy (S_TiNb) versus smooth titanium commercially pure (S_TiCp)—a reference in implantology. All experiments were performed in vitro using human osteoblast-like SaOs-2 and monocyte THP-1 cell lines as models. Cell adhesion and growth morphology were determined by scanning electron microscopy, while cell viability was evaluated using WST-1 assay. Because niobate anions or niobium nanoparticles can be released from implants during biomaterial-cell interaction, potential immunotoxicity of potassium niobate (KNbO₃₎ salt was evaluated by examining both metabolic activity and transcriptomic profiling of treated THP-1 monocytes. The main findings of this study are that S_TiCp and S_TiNb discs do not show an impact on the proliferation and viability of SaOs-2 cells compared to polystyrene surfaces, whereas a significant decrease in THP-1 cells’ viability and metabolic activity was observed in the presence of S_TiNb discs compared to the control group. However, no significant changes were found neither at the metabolic activity nor at the transcriptomic level of THP-1 monocytes exposed to KNbO₃ salt, suggesting that niobium has no effect on the immune system. Overall, these data imply a possible toxicity of S_TiNb discs toward THP-1 cells, which may not be directly related to niobium but perhaps to the manufacturing process of titanium-niobium alloy. Thus, this limitation must be overcome to make titanium alloy an excellent material for medical applications.

In-Vitro Phenotypic Response of Human Osteoblasts to Different Degrees of Titanium Surface Roughness

Objectives: This study aimed to investigate human osteoblast (HOB) responses towards different degrees of titanium (Ti) implant surface roughness. Methods: Four degrees of Ti surface roughness were investigated on a micrometer roughness scale: smooth (S: 0.08−0.1 µm), minimally rough (MM: 0.3−0.5 µm), moderately rough (MR: 1.2−1.4 µm), and rough (R: 3.3−3.7 µm). HOB cells were cultured, expanded, and maintained according to the supplier’s protocol. Cell proliferation and cytotoxicity were assessed at day 1, 3, 5, and 10 using alamarBlue and lactate dehydrogenase colorimetric assays. Data were analyzed with one-way ANOVA, two-way ANOVA, and Tukey’s post hoc test (p = 0.05 for all tests). Results: There was no significant difference in the cell proliferation or cytotoxicity of the HOB cells in contact with the different degrees of Ti surface roughness. There was, however, a significant time effect on cell proliferation (p < 0.0001) with different exposure durations for each roughness degree. Furthermore, a positive correlation (non-significant) between proliferation and cytotoxicity was observed for all investigated degrees of surface roughness. Conclusion: All investigated roughness degrees showed comparable HOB proliferation, with the MR surface presenting the highest percentage, followed by the R, MM, ad S, surfaces, respectively. The S surface showed the highest cytotoxic effect on HOBs; however, it did not reach the cytotoxic level suggested by the ISO for any medical device to be considered cytotoxic.

Modifying an Implant: A Mini-review of Dental Implant Biomaterials

Dental implants have been used as far back as 2000BC, and since then have developed into highly sophisticated solutions for tooth replacement. It is becoming increasingly important for the materials used in dental implants to exhibit and maintain favorable long-term mechanical, biological and more recently, aesthetic properties. This review aims to assess the biomaterials used in modern dental implants, introducing their properties, and concentrating on modifications to improve these biomaterials. Focus is drawn to the prominent biomaterials, titanium (Ti) and zirconia due to their prevalence in implant dentistry. Additionally, novel coatings and materials with potential use as viable improvements or alternatives are reviewed. An effective dental biomaterial should osseointegrate, maintain structural integrity, resist corrosion and infection, and not cause systemic toxicity or cytotoxicity. Current materials such as bioactive glass offer protection against biofilm formation, and when combined with a titanium‐zirconium (TiZr) alloy, provide a reliable combination of properties to represent a competitive alternative. Further long-term clinical studies are needed to inform the development of next-generation materials.Significance StatementBiomaterials have become essential for modern implants. A suitable implant biomaterial integrates into the body to perform a key function, whilst minimizing negative immune response. Focusing on dentistry, the use of dental implants for tooth replacement requires a balance between bodily response, mechanical structure and performance, and aesthetics. This mini-review addresses the use of biomaterials in dental implants with significant comparisons drawn between Ti and zirconia. Attention is drawn to optimizing surface modification processes and the additional use of coatings. Alternatives and novel developments are addressed, providing potential implications of combining biomaterials to form novel composites that combine and synergize the benefits of each material.

In Vitro Corrosion and Tribocorrosion Performance of Biocompatible Carbide Coatings

The present study aims to explain the corrosion and the tribocorrosion performance in simulated conditions of the human body by the level of stress, adhesion of coating to substrate, roughness, and hardness. The coatings were synthesized by the cathodic arc evaporation method on 316L stainless steel substrates to be used for load bearing implants. Structure, elemental, and phase compositions were studied by means of energy dispersive spectrometry and X-ray diffraction, respectively. The grain size and strain of the coatings were determined by the Williamson–Hall plot method. Tests on hardness, adhesion, roughness, and electrochemical behavior in 0.9% NaCl solution at 37 ± 0.5 °C were carried out. Tribocorrosion performances, evaluated by measuring the friction coefficient and wear rate, were conducted in 0.9% NaCl solution using the pin on disc method at 37 ± 0.5 °C. TiC and ZrC exhibited a (111) preferred orientation, while TiNbC had a (200) orientation and the smallest crystallite size (8.1 nm). TiC was rougher than ZrC and TiNbC; the lowest roughness was found for TiNbC coatings. The highest hardness and adhesion values were found for TiNbC, followed by TiC and the ZrC. All coatings improved the corrosion resistance of 316L steels, but TiNbC showed the best corrosion behavior. TiNbC had the lowest friction coefficient (1.6) and wear rate (0.99 × 10−5 mm3·N−1∙m−1) values, indicating the best tribocorrosive performance in 0.9% NaCl at 37 ± 0.5 °C.

Comparison of the Use of Titanium–Zirconium Alloy and Titanium Alloy in Dental Implants: A Systematic Review and Meta-Analysis

The aim of this study was to compare the values of bone-implant contact (BIC) and removal torque (RTQ) reported in different animal studies for titanium–zirconium (TiZr) and titanium (Ti) dental implants. This review has been registered at PROSPERO under number CRD42016047745. We undertook an electronic search for data published up until November 2017 using the PubMed/Medline, Embase, and The Cochrane Library databases. Eligibility criteria included in vivo studies, comparisons between Ti and TiZr implants in the same study, and studies published in English that evaluated BIC and RTQ. After inclusion criteria, 8 studies were assessed for eligibility. Of the 8 studies, 7 analyzed BIC outcome and 3 analyzed RTQ outcome. Among such studies, 6 studies were considered for meta-analysis of quantitative for BIC and 2 studies for RTQ. There was no significant difference for BIC analysis (P = .89; random ration [RR]: −0.21; 95% confidence interval [CI]: −3.14 to 2.72). The heterogeneity of the primary outcome studies was considered low (7.19; P = .21; I2: 30%). However, the RTQ analysis showed different results favoring the TiZr dental implants (P = .001; RR: 23.62; 95%CI: 9.15 to 38.10). Low heterogeneity was observed for RTQ (χ2: 1.25; P = .26; I2: 20%). Within the limitations of this study, there was no difference between TiZr and Ti alloys implants in terms of BIC. However, TiZr implants had higher RTQ than Ti alloys.

Osteogenic potential of laser modified and conditioned titanium zirconium surfaces

Statement of Problem:

The osseointegration of dental implant is related to their composition and surface treatment. Titanium zirconium (TiZr) has been introduced as an alternative to the commercially pure titanium and its alloys as dental implant material, which is attributed to its superior mechanical and biological properties. Surface treatments of TiZr have been introduced to enhance their osseointegration ability; however, reliable, easy to use surface modification technique has not been established.

Purpose:

The purpose of this study was to evaluate and compare the effect of neodymium-doped yttrium aluminum garnet (Nd-YAG) laser surface treatment of TiZr implant alloy on their osteogenic potential.

Materials and Methods:

Twenty disc-shaped samples of 5 mm diameter and 2 mm height were milled from the TiZr alloy ingot. The polished discs were ultrasonically cleaned in distilled water. Ten samples each were randomly selected as Group A control samples and Group B consisted of Nd-YAG laser surface etched and conditioned test samples. These were evaluated for cellular response. Cellular adhesion and proliferation were quantified, and the results were statistically analyzed using nonparametric analysis. Cellular morphology was observed using electron and epiflurosence microscopy.

Results:

Nd-YAG laser surface modified and conditioned TiZr samples increased the osteogenic potential.

Conclusion:

Nd-YAG laser surface modification of TiZr, improves the cellular activity, surface roughness, and wettability, thereby increasing the osteogenic potential.

A Review of Titanium Zirconium (TiZr) Alloys for Use in Endosseous Dental Implants

Dental implants made from binary titanium-zirconium (TiZr) alloys have shown promise as a high strength, yet biocompatible alternative to pure titanium, particularly for applications requiring small diameter implants. The aim of this review is to summarize existing literature reporting on the use of binary TiZr alloys for endosseous dental implant applications as tested in vitro, in animals and clinically. And furthermore to show that TiZr is “at least as good as” pure titanium in terms of biocompatibility and osseointergration. From the twelve papers that met the inclusion criteria, the current literature confirms that TiZr alloys produce small diameter implants with a strength up to 40% higher than conventional, cold-worked, grade IV titanium implants, and with a corrosion resistance and biocompatibility that is at least as good as pure titanium. The surface structure of TiZr is compatible with established surface treatments proven to aid in the osseointegration of titanium implants. Furthermore, binary TiZr alloys have been shown to achieve good osseointegration and high success rates both in animal and in clinical studies.

In-vitro and in-vivo evaluation of a new Ti-15Mo-1Bi alloy

The newly developed Ti-15Mo-1Bi alloy not only possesses all the desirable mechanical properties inherent to beta-Ti Mo alloys, but may even enjoy better clinical applicability with the addition of bismuth element, which has long been administered as antibacterial and antitumor medicines. A significantly higher viability of 3T3 cells was demonstrated when they were grown on Ti-15Mo-1Bi alloy than on Ti-15Mo and Ti-6Al-4V. Cells incubated in the medium conditioned by Bi powder at 37 degrees C for 96 h exhibited viability similar to that in the blank group and higher than that in the Ni conditioned group. In vivo experiments using 6 mm x 2 mm metal pin implanted into the epicondyle of rabbit femur revealed superior potential of new bone growth and better persistence of the deposited bony tissue with the Ti-15Mo-1Bi alloy in contrast to that with Ti-6Al-4V. The difference is evident at 12th week and become even more prominent after 26 weeks, with the new bone area measuring 249% of that around Ti-6Al-4V alloy. In summary, Ti-15Mo-1Bi alloys show no cytotoxicity in the in-vitro test and demonstrates superior ability to retain bone in the in-vivo implantation experiment as compared with Ti-6Al-4V alloys.

Bone formation at the surface of low modulus Ti-7.5Mo implants in rabbit femur

The biocompatibility of the Ti-7.5Mo alloy was examined, because the alloy has a high-strength/modulus ratio and thus is a potential candidate for orthopedic applications. Cell viability assay using 3T3 cells revealed that the Ti-7.5Mo did not induce apparent cell death, when the cells were grown on disks made of the alloy or incubated with the alloy-conditioned medium at 37 or 72 degrees C for 24-72h. The Ti-6Al-4V alloy was used as a control and did not cause apparent cell death either. Moreover, pins of 6mm long and 2mm in diameter of Ti-7.5Mo and Ti-6Al-4V were implanted into the left and right rabbit femurs, respectively, for 6, 12 and 26 weeks. New bone tissue grew to surround the pins, which spanned cortical and marrow regions, as shown by toluidine blue-stained bone sections of the three time points. Strikingly, the amount of new bone encircling the Ti-7.5Mo implant was approximate two-folds of that at Ti-6Al-4V by 26 weeks post-implantation. This facilitation of bone formation could be associated with the unique properties, such as a low modulus and the composition of Mo, of the Ti-7.5Mo.