Ultrathin ALD Coatings of Zr and V Oxides on Anodic TiO2 Nanotube Layers: Comparison of the Osteoblast Cell Growth

The current study investigates and compares the biological effects of ultrathin conformal coatings of zirconium dioxide (ZrO2) and vanadium pentoxide (V2O5) on osteoblastic MG-63 cells grown on TiO2 nanotube layers (TNTs). Coatings were achieved by the atomic layer deposition (ALD) technique. TNTs with average tube diameters of 15, 30, and 100 nm were fabricated on Ti substrates (via electrochemical anodization) and were used as primary substrates for the study. The MG-63 cell growth and proliferation after 48 h of incubation on hybrid TNTs/ZrO2 and TNTs/V2O5 surfaces was evaluated in comparison to the uncoated TNTs of each diameter. The density of viable MG-63 cells was assessed for all the TNT surfaces, along with the cell morphology and the spreading behavior (i.e., the cell length). The ultrathin coatings retained the original morphology of the TNTs but changed the surface chemical composition, wettability, and cell behavior, whose interplay is the subject of the present investigation. These findings offer interesting views on the influence of the composition of biomedical implant surfaces, triggered by ALD ultrathin coatings on them. The outcomes of this work shed light on the assessment of the biocompatibility of the two different ALD coatings.

Zirconia Dental Implant Designs and Surface Modifications: A Narrative Review

Titanium currently has a well-established position as the gold standard for manufacturing dental implants; however, it is not free of flaws. Mentions of possible soft-tissue discoloration, corrosion, and possible allergic reactions have led to the development of zirconia dental implants. Various techniques for the surface modification of titanium have been applied to increase titanium implants' ability to osseointegrate. Similarly, to achieve the best possible results, zirconia dental implants have also had their surface modified to promote proper healing and satisfactory long-term results. Despite zirconium oxide being a ceramic material, not simply a metal, there have been mentions of it being susceptible to corrosion too. In this article, we aim to review the literature available on zirconia implants, the available techniques for the surface modification of zirconia, and the effects of these techniques on zirconia's biological properties. Zirconia's biocompatibility and ability to osseointegrate appears unquestionably good. Despite some of its mechanical properties being, factually, inferior to those of titanium, the benefits seem to outweigh the drawbacks. Zirconia implants show very good success rates in clinical research. This is partially due to available methods of surface treatment, including nanotopography alterations, which allow for improved wettability, bone-to-implant contact, and osteointegration in general.

Fracture Resistance of a Bone-Level Two-Piece Zirconia Oral Implant System-The Influence of Artificial Loading and Hydrothermal Aging

Preclinical and clinical research on two-piece zirconia implants are warranted. Therefore, we evaluated the in vitro fracture resistance of such a zirconia oral implant system. The present study comprised 32 two-piece zirconia implants and abutments attached to the implants using a titanium (n = 16) or a zirconia abutment screw (n = 16). Both groups were subdivided (n = 8): group T-0 comprised implants with a titanium abutment screw and no artificial loading; group T-HL was the titanium screw group exposed to hydro-thermomechanical loading in a chewing simulator; group Z-0 was the zirconia abutment screw group with no artificial loading; and group Z-HL comprised the zirconia screw group with hydro-thermomechanical loading. Groups T-HL and Z-HL were loaded with 98 N and aged in 85 °C hot water for 107 chewing cycles. All samples were loaded to fracture. Kruskal-Wallis tests were executed to assess the loading/bending moment group differences. The significance level was established at a probability of 0.05. During the artificial loading, there was a single occurrence of an implant fracture. The mean fracture resistances measured in a universal testing machine were 749 N for group T-0, 828 N for group Z-0, 652 N for group T-HL, and 826 N for group Z-HL. The corresponding bending moments were as follows: group T-0, 411 Ncm; group Z-0, 452 Ncm; group T-HL, 356 Ncm; and group Z-HL, 456 Ncm. There were no statistically significant differences found between the experimental groups. Therefore, the conclusion was that loading and aging did not diminish the fracture resistance of the evaluated implant system.

Antibiofilm peptides enhance the corrosion resistance of titanium in the presence of Streptococcus mutans

Titanium alloys have gained popularity in implant dentistry for the restoration of missing teeth and related hard tissues because of their biocompatibility and enhanced strength. However, titanium corrosion and infection caused by microbial biofilms remains a significant clinical challenge leading to implant failure. This study aimed to evaluate the effectiveness of antibiofilm peptides 1018 and DJK-5 on the corrosion resistance of titanium in the presence of Streptococcus mutans. Commercially pure titanium disks were prepared and used to form biofilms. The disks were randomly assigned to different treatment groups (exposed to S. mutans supplied with sucrose) including a positive control with untreated biofilms, peptides 1018 or DJK-5 at concentrations of 5 μg/mL or 10 μg/mL, and a negative control with no S. mutans. Dynamic biofilm growth and pH variation of all disks were measured after one or two treatment periods of 48 h. After incubation, the dead bacterial proportion, surface morphology, and electrochemical behaviors of the disks were determined. The results showed that peptides 1018 and DJK-5 exhibited significantly higher dead bacterial proportions than the positive control group in a concentration dependent manner (p < 0.01), as well as far less defects in microstructure. DJK-5 at 10 μg/mL killed 84.82% of biofilms and inhibited biofilm growth, preventing acidification due to S. mutans and maintaining a neutral pH. Potential polarization and electrochemical impedance spectroscopy data revealed that both peptides significantly reduced the corrosion and passive currents on titanium compared to titanium surfaces with untreated biofilms, and increased the resistance of the passive film (p < 0.05), with 10 μg/mL of DJK-5 achieving the greatest effect. These findings demonstrated that antibiofilm peptides are effective in promoting corrosion resistance of titanium against S. mutans, suggesting a promising strategy to enhance the stability of dental implants by endowing them with antibiofilm and anticorrosion properties.

Toward Elimination of Electrochemical Corrosion in Dental Implants: A Zirconia-Titanium Composite Prototype

Background Titanium dental implants (e.g., Nobel Biocare, Switzerland) are routinely used as support for dental restoration. Titanium has been the material of choice due to its corrosion resistance and ability to integrate with bone. Nevertheless, corrosion and titanium dissolution do occur. Compared to control, peri-implantitis tissue biopsies have been shown to contain high concentrations of dissolved titanium as well as metal particles. Dissolved titanium species have been found to be associated with the structure/diversity of the subgingival plaque microbiome and the extent of global methylation. Of note, peri-implantitis and peri-implant mucositis are common biological complications of implant therapy. Microorganisms and local inflammation together with a gradient of oxygen have been proven to form an electrochemical fuel cell, which generates the current that flows through the body of the titanium implant. Effectively, the fuel cell reduces oxygen and oxidizes titanium that turns into a soluble form. We are proposing a new zirconia-titanium composite implant design whereby the electrical current is disrupted while other properties are still conducive to osseointegration. Methodology Biocompatible zirconia bolts were treated with hydrofluoric acid (HF) and coated with titanium in a vacuum evaporator. The coating was masked with nail polish, and unmasked areas were etched with HF followed by mask removal with a solvent. Microbial challenges were conducted with a volunteer's plaque. Regular implant (control) and the prototype were inserted into simulated peri-implant environments implemented as a fiberglass sleeve immersed into a growth medium. After a five-day growth, samples were taken and HNO3 digested. Dissolved titanium was evaluated by inductively coupled plasma mass spectrometry. Results Proof-of-concept implant prototypes were successfully created. Vacuum deposition results in reproducible stable titanium coating. The thickness of the titanium coating was estimated using atomic force microscopy. A microbial challenge revealed that compared to the commercial titanium implant, the new implant prototype showed decreased amounts of corrosion-leached titanium. Conclusions We demonstrate a path forward toward a new design of a dental implant, whereby corrosion-induced electrical currents are interrupted resulting in a decreased amount of dissolved titanium.

Influence of a D-enantiomeric peptide on the anticorrosion ability of titanium with different surface roughness against Streptococcus mutans biofilms

OBJECTIVE

To investigate the effectiveness of a d-enantiomeric antibiofilm peptide (DJK-5) on the anticorrosion ability of titanium (Ti) with different surface roughness against Streptococcus mutans biofilms.

METHODS

Commercially pure Ti disks with machined (MA, smooth) or sandblasted + acid-etched (SLA, rough) surfaces were prepared and characterized. All disks were divided into three groups: a positive control (PC) group with S. mutans, a DJK-5-treated group, and a negative control (NC) group without S. mutans. Biofilm formation and corrosion on Ti surfaces were determined by confocal laser scanning microscopy and scanning electron microscopy after 2 and 6 days, and the electrochemical properties were evaluated.

RESULTS

Ten μg/mL of DJK-5 killed 83.3 % and 87.4 % of biofilms on SLA and MA Ti surfaces, respectively after 2 days, and 72.9 % and 77.7 % after 6 days, with more bacteria surviving on SLA surfaces with higher roughness (p < 0.05). DJK-5 treatment induced less surface defects with tiny pit corrosion than PC. DJK-5 treatment when compared to PC, led to electrochemical properties more reflecting NC surfaces, including significantly less negative corrosion potential, lower corrosion current, and higher passive film resistance (p < 0.05). SLA surfaces exhibited higher current density and lower resistance than MA surfaces (p < 0.05).

CONCLUSION

DJK-5 effectively enhanced the corrosion resistance of Ti with different surface roughness while killing S. mutans biofilms, and smooth surfaces were more susceptible to peptide treatment.

CLINICAL SIGNIFICANCE

The antibiofilm peptide is promising for promoting the anticorrosion ability of Ti against biofilms, thereby preventing biofilm-related infections.

Titanium particles in peri-implantitis: distribution, pathogenesis and prospects

Peri-implantitis is one of the most important biological complications in the field of oral implantology. Identifying the causative factors of peri-implant inflammation and osteolysis is crucial for the disease's prevention and treatment. The underlying risk factors and detailed pathogenesis of peri-implantitis remain to be elucidated. Titanium-based implants as the most widely used implant inevitably release titanium particles into the surrounding tissue. Notably, the concentration of titanium particles increases significantly at peri-implantitis sites, suggesting titanium particles as a potential risk factor for the condition. Previous studies have indicated that titanium particles can induce peripheral osteolysis and foster the development of aseptic osteoarthritis in orthopedic joint replacement. However, it remains unconfirmed whether this phenomenon also triggers inflammation and bone resorption in peri-implant tissues. This review summarizes the distribution of titanium particles around the implant, the potential roles in peri-implantitis and the prevalent prevention strategies, which expects to provide new directions for the study of the pathogenesis and treatment of peri-implantitis.

Fit and forget: The future of dental implant therapy via nanotechnology

Unlike orthopedic implants, dental implants require the orchestration of both osseointegration at the bone-implant interface and soft-tissue integration at the transmucosal region in a complex oral micro-environment with ubiquitous pathogenic bacteria. This represents a very challenging environment for early acceptance and long-term survival of dental implants, especially in compromised patient conditions, including aged, smoking and diabetic patients. Enabling advanced local therapy from the surface of titanium-based dental implants via novel nano-engineering strategies is emerging. This includes anodized nano-engineered implants eluting growth factors, antibiotics, therapeutic nanoparticles and biopolymers to achieve maximum localized therapeutic action. An important criterion is balancing bioactivity enhancement and therapy (like bactericidal efficacy) without causing cytotoxicity. Critical research gaps still need to be addressed to enable the clinical translation of these therapeutic dental implants. This review informs the latest developments, challenges and future directions in this domain to enable the successful fabrication of clinically-translatable therapeutic dental implants that would allow for long-term success, even in compromised patient conditions.

Enhanced Corrosion Resistance and Local Therapy from Nano-Engineered Titanium Dental Implants

Titanium is the ideal material for fabricating dental implants with favorable biocompatibility and biomechanics. However, the chemical corrosions arising from interaction with the surrounding tissues and fluids in oral cavity can challenge the integrity of Ti implants and leach Ti ions/nanoparticles, thereby causing cytotoxicity. Various nanoscale surface modifications have been performed to augment the chemical and electrochemical stability of Ti-based dental implants, and this review discusses and details these advances. For instance, depositing nanowires/nanoparticles via alkali-heat treatment and plasma spraying results in the fabrication of a nanostructured layer to reduce chemical corrosion. Further, refining the grain size to nanoscale could enhance Ti implants' mechanical and chemical stability by alleviating the internal strain and establishing a uniform TiO₂ layer. More recently, electrochemical anodization (EA) has emerged as a promising method to fabricate controlled TiO₂ nanostructures on Ti dental implants. These anodized implants enhance Ti implants' corrosion resistance and bioactivity. A particular focus of this review is to highlight critical advances in anodized Ti implants with nanotubes/nanopores for local drug delivery of potent therapeutics to augment osseo- and soft-tissue integration. This review aims to improve the understanding of novel nano-engineered Ti dental implant modifications, focusing on anodized nanostructures to fabricate the next generation of therapeutic and corrosion-resistant dental implants. The review explores the latest developments, clinical translation challenges, and future directions to assist in developing the next generation of dental implants that will survive long-term in the complex corrosive oral microenvironment.

Silver Nanoparticles Produced by Laser Ablation and Re-Irradiation Are Effective Preventing Peri-Implantitis Multispecies Biofilm Formation

Implant-associated infection due to biofilm formation is a growing problem. Given that silver nanoparticles (Ag-NPs) have shown antibacterial effects, our goal is to study their effect against multispecies biofilm involved in the development of peri-implantitis. To this purpose, Ag-NPs were synthesized by laser ablation in de-ionized water using two different lasers, leading to the production of colloidal suspensions. Subsequently, part of each suspension was subjected to irradiation one and three times with the same laser source with which it was obtained. Ag-NPs were immobilized on the surface of titanium discs and the resultant materials were compared with unmodified titanium coupons. Nanoparticles were physico-chemically analysed to determine their shape, crystallinity, chemical composition, and mean diameter. The materials were incubated for 90 min or 48 h, to evaluate bacterial adhesion or biofilm formation respectively with Staphylococcus aureus or oral mixed bacterial flora composed of Streptococcus oralis, Actinomyces naeslundii, Veionella dispar, and Porphyromonas gingivalis. Ag-NPs help prevent the formation of biofilms both by S. aureus and by mixed oral bacterial flora. Nanoparticles re-irradiated three times showed the biggest antimicrobial effects. Modifying dental implants in this way could prevent the development of peri-implantitis.

A two-phase and long-lasting multi-antibacterial coating enables titanium biomaterials to prevent implants-related infections

In clinical work, the main challenges for titanium (Ti) implantation are bacterial infection and aseptic loosening, which severely affect the survival rate of implants. The first 4 weeks post-operation is the infection peak phase of implants. Inhibiting implant infection caused by bacteria adhesion and proliferation during the early phase as well as promoting subsequent osteointegration is essential for implant success. Herein, we constructed a quaternary ammonium carboxymethyl chitosan (QCMC), collagen (COL Ⅰ) and hydroxyapatite (HAP) multilayers coating on Ti substrates via a modified layer-by-layer (LBL) technique and polymerization of dopamine. The QCMC/COL/HAP coating exhibited a multi-antibacterial property with a two-phase function: (1) At the first 4 weeks post-operation, the covalently bonded QCMC could be slowly degraded and demonstrated both contact-killing and release-killing properties during the infection peak phase; (2) At the second phase, osteogenesis and osseointegration-promotion capabilities were enhanced by HAP under the effective control of infection. The multifilm coating was degraded for more than 45 days under the action of collagenase Ⅰ, and displayed good biocompatibility in vivo and in vitro. Most importantly, the coating exhibited a long-lasting antibacterial activity for more than 3 months, against the main pathogenic bacteria of peri-implant infections. Both in vitro studies and in vivo animal models revealed a desirable osteogenic differentiation capacity of Ti-CCH. Therefore, our study reports a two-phase, long-lasting multi-antibacterial coating on Ti-CCH and indicates potential applications of the modified LBL strategy in orthopaedic fields, which is enlightening for developing practical implant and scaffold materials.

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Developing a QCMC/COL/HAP multifilm coating via modified layer-by-layer technique and self-polymerization of dopamine.

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The QCMC/COL/HAP coating exhibited desirable mechanical properties and excellent biocompatibility.

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The release kinetics endowed the QCMC/COL/HAP coating with multi-antibacterial activity at the first phase after operation.

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The QCMC/COL/HAP coating could improve osseointegration at the second phase of post-operation.

ZrO2/ZnO/TiO2 Nanocomposite Coatings on Stainless Steel for Improved Corrosion Resistance, Biocompatibility, and Antimicrobial Activity

The ultrathin nanocomposite coatings made of zirconium oxide (ZrO₂), zinc oxide (ZnO), and titanium oxide (TiO₂) on stainless steel (SS) were prepared by the radio frequency sputtering method, and the effects of the nanocomposite coating on corrosion protection and antibacterial activities of nanocomposite coated SS were investigated. Scanning electron microscopy was conducted to observe surface morphology of nanocomposite coatings with distinct distribution of grains with the formation on SS substrate. From the electrochemical impedance spectroscopy results, ZrO₂/ZnO/TiO₂ nanocomposite coating showed excellent corrosion protection performance at 37 °C during immersion in simulated body fluid and saliva solution for 12 and 4 weeks, respectively. The impedance of ZrO₂/ZnO/TiO₂ (40/10/50) nanocomposite coated SS exhibited values about 5 orders of magnitude higher than that of uncoated SS with polarization at the low-frequency region. Cell viability of ZrO₂/ZnO/TiO₂ nanocomposite coated SS was examined under mouse fibroblasts culture (L929), and it was observed that the nanocomposite coating improves proliferation through effective cellular attachment compared to uncoated SS. From the antimicrobial activity results, ZrO₂/ZnO/TiO₂ nanocomposite-coated SS showed killing efficiency of 81.2% and 72.4% against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, respectively.

Oral prosthetic microbiology: aspects related to the oral microbiome, surface properties, and strategies for controlling biofilms

The oral cavity is an environment that allows for the development of complex ecosystems; the placement of prosthetic devices as a consequence of partial or total tooth loss may alter the diversity of microbial communities. Biofilms on the surface of materials used in dental prostheses can promote important changes in the mechanic and aesthetic properties of the material itself and may cause local and systemic diseases for the prosthetic wearer. This review presents the main features of the oral microbiome associated with complete or partial dentures and dental implants. The main diseases associated with microbial colonization of prosthetic surfaces, factors that may affect biofilm formation on prosthetic materials, as well as novel alternative therapies aiming to reduce biofilm formation and/or to eradicate biofilms formed on these materials are also explored.

Titanium Nanotube Modified With Silver Cross-Linked Basic Fibroblast Growth Factor Improves Osteoblastic Activities of Dental Pulp Stem Cells and Antibacterial Effect

Titanium modifications with different silver loading methods demonstrate excellent antibacterial properties. Yet pure silver nanoparticles with limited bioactive properties may delay regeneration of bone surrounding the dental implant. Therefore, loading silver with bioactive drugs on titanium surfaces seems to be a very promising strategy. Herein, we designed a silver (Ag) step-by-step cross-linking with the basic fibroblast growth factor (bFGF) by polydopamine (PDA) and heparin on titanium nanotube (TNT) as its cargo (TNT/PDA/Ag/bFGF) to improve the implant surface. Our results showed that TNT/PDA/Ag/bFGF significantly enhanced the osteogenic differentiation of dental pulp stem cells (DPSCs). It also showed an excellent effect in bacterial inhibition and a reduction of pro-inflammatory factors through inhibition of M1 macrophage activity. These results showed that bFGF cross-linked silver coating on TNTs presented good osteogenic differentiation and early anti-infiammatory and antibacterial properties. Together, this novel design on titanium provides a promising therapeutic for dental implants.

Effect of implant cleaning on titanium particle dissolution and cytocompatibility

BACKGROUND

Peri-implantitis treatments are mainly based on protocols for teeth but have not shown favorable outcomes for implants. The potential role of titanium dissolution products in peri-implantitis necessitate the consideration of material properties in devising treatment protocols. We assessed implant cleaning interventions on (1) bacterial removal from Ti-bound biofilms, (2) Ti surface alterations and related Ti particle dissolution, and (3) cytocompatibility.

METHODS

Acid-etched Ti discs were inoculated with human peri-implant plaque biofilms and mechanical antimicrobial interventions were applied on the Ti-bound biofilms for 30 seconds each: (1) rotary nylon brush; (2) Ti brush; (3) water-jet on high and (4) low, and compared to sterile, untreated and Chlorhexidine-treated controls. We assessed colony forming units (CFU) counts, biofilm removal, surface changes via scanning electron microscopy (SEM) and atomic force microscopy (AFM), and Ti dissolution via light microscopy and Inductively-coupled Mass Spectrometry (ICP-MS). Biological effects of Ti particles and surfaces changes were assessed using NIH/3T3 fibroblasts and MG-63 osteoblastic cell lines, respectively.

RESULTS

Sequencing revealed that the human biofilm model supported a diverse biofilm including known peri-implant pathogens. WJ and Nylon brush were most effective in reducing CFU counts (P < 0.01 versus control), whereas Chlorhexidine was least effective; biofilm imaging results were confirmatory. Ti brushes led to visible streaks on the treated surfaces, reduced corrosion resistance and increased Ti dissolution over 30 days of material aging as compared to controls, which increase was amplified in the presence of bacteria (all P-val < 0.05). Ti particles exerted cytotoxic effects against fibroblasts, whereas surfaces altered by Ti brushes exhibited reduced osteoconductivity versus controls (P < 0.05).

CONCLUSIONS

Present findings support that mechanical treatment strategies selected for implant biofilm removal may lead to Ti dissolution. Ti dissolution should become an important consideration in the clinical selection of peri-implantitis treatments and a necessary criterion for the regulatory approval of instruments for implant hygiene.

Bone loss around implants-is it metallosis?

Most would agree that the etiology of dental implant failure is related to oral biofilm. At present one group of scientists and clinicians feel that biofilm is solely responsible for bone loss around the devices. However, there is strong evidence that particles and ions of titanium released into the surrounding tissues by the action of biofilm and/or mechanical forces, a process termed metallosis, can be responsible for bone loss around some dental implants. These findings are reinforced by similar responses found around failed metal on metal joint prostheses. Both possible etiologies are discussed in detail in this commentary.

Contamination of titanium dental implants: a narrative review

Contamination of titanium dental implants may lead to implant failure. There are two major types of contaminants: the inorganic and organic contaminants. The inorganic contaminants mostly consist of elements such as calcium, phosphorus, chlorine, sulphur, sodium, silicon, fluorine and some organic carbons. Whereas organic contaminants consist of hydrocarbon, carboxylates, salts of organic acids, nitrogen from ammonium and bacterial cells/byproducts. Contaminants can alter the surface energy, chemical purity, thickness and composition of the oxide layer, however, we lack clinical evidence that contaminations have any effect at all. However, surface cleanliness seems to be essential for implant osseointegration.These contaminants may cause dental implants to fail in its function to restore missing teeth and also cause a financial burden to the patient and the health care services to invest in decontamination methods. Therefore, it is important to discuss the aetiology of dental implant failures. In this narrative review, we discuss two major types of contaminants: the inorganic and organic contaminants including bacterial contaminants. This review also aims to discuss the potential effect of contamination on Ti dental implants.

The Trends of TiZr Alloy Research as a Viable Alternative for Ti and Ti16 Zr Roxolid Dental Implants

Despite many discussions about Ti versus Zr, Ti remains the golden standard for dental implants. With the extended use of implants, their rejection in peri-implantitis due to material properties is going to be an important part of oral health problems. Extended use of implants leading to a statistical increase in implant rejection associated with peri-implantitis raises concerns in selecting better implant materials. In this context, starting in the last decade, investigation and use of TiZr alloys as alternatives for Ti in oral dentistry became increasingly more viable. Based on existing new results for Ti16Zr (Roxolid) implants and Ti50Zr alloy behaviour in oral environments, this paper presents the trends of research concerning the electrochemical stability, mechanical, and biological properties of this alloy with treated and untreated surfaces. The surface treatments were mostly performed by anodizing the alloy in various conditions as a non-sophisticated and cheap procedure, leading to nanostructures such as nanopores and nanotubes. The drug loading and release from nanostructured Ti50Zr as an important perspective in oral implant applications is discussed and promoted as well.

Modifying Adhesive Materials to Improve the Longevity of Resinous Restorations

Dental caries is a common disease on a global scale. Resin composites are the most popular materials to restore caries by bonding to tooth tissues via adhesives. However, multiple factors, such as microleakage and recurrent caries, impair the durability of resinous restorations. Various innovative methods have been applied to develop adhesives with particular functions to tackle these problems, such as incorporating matrix metalloproteinase inhibitors, antibacterial or remineralizing agents into bonding systems, as well as improving the mechanical/chemical properties of adhesives, even combining these methods. This review will sum up the latest achievements in this field.