Surface Modified Techniques and Emerging Functional Coating of Dental Implants

Antimicrobial Effects of Metal Coatings or Physical, Chemical Modifications of Titanium Dental Implant Surfaces for Prevention of Peri-Implantitis: A Systematic Review of In Vivo Studies

Introduction: Peri-implantitis poses a significant challenge for implant dentistry due to its association with bacterial colonization on implant surfaces and the complexity of its management. This systematic review aims to assess evidence from in vivo studies regarding the antimicrobial efficacy of titanium (Ti) dental implant surfaces following physical/chemical modifications or the application of various metal element coatings in preventing bacterial growth associated with peri-implantitis. Materials and Methods: A literature review was conducted across four scientific databases (PubMed, Embase, Scopus, Web of Science), encompassing in vivo studies published between 2013 and 2024, and 18 reports were included in the systematic review. Results: The findings suggest that titanium dental implant surfaces, following physical/chemical modifications and metal element coatings, exhibit antimicrobial effects against bacteria associated with peri-implantitis in humans and various animal models. Conclusions: The reviewed studies indicated a reduction in bacterial colonization, diminished biofilm formation, and decreased signs of inflammation in the peri-implant tissues, which provides evidence that physical/chemical alterations on titanium dental implant surfaces or metal element coatings, like silver (Ag), zinc (Zn), magnesium (Mg), and copper (Cu), demonstrate antimicrobial properties in in vivo studies. However, caution is warranted when translating findings to clinical practice due to methodological disparities and high bias risks. Further larger-scale clinical trials are imperative to assess their long-term efficacy and validate their clinical applicability.

Electrospun PVP Fibers as Carriers of Ca2+ Ions to Improve the Osteoinductivity of Titanium-Based Dental Implants

Although titanium and its alloys are widely used as dental implants, they cannot induce the formation of new bone around the implant, which is a basis for the functional integrity and long-term stability of implants. This study focused on the functionalization of the titanium/titanium oxide surface as the gold standard for dental implants, with electrospun composite fibers consisting of polyvinylpyrrolidone and Ca2+ ions. Polymer fibers as carriers of Ca2+ ions should gradually dissolve, releasing Ca2+ ions into the environment of the implant when it is immersed in a model electrolyte of artificial saliva. Scanning electron microscopy, energy dispersive X-ray spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy confirmed the successful formation of a porous network of composite fibers on the titanium/titanium oxide surface. The mechanism of the formation of the composite fibers was investigated in detail by quantum chemical calculations at the density functional theory level based on the simulation of possible molecular interactions between Ca2+ ions, polymer fibers and titanium substrate. During the 7-day immersion of the functionalized titanium in artificial saliva, the processes on the titanium/titanium oxide/composite fibers/artificial saliva interface were monitored by electrochemical impedance spectroscopy. It can be concluded from all the results that the composite fibers formed on titanium have application potential for the development of osteoinductive and thus more biocompatible dental implants.

A Comprehensive Review of the Contemporary Methods for Enhancing Osseointegration and the Antimicrobial Properties of Titanium Dental Implants

Titanium dental implants with various restorative options are popular for replacing missing teeth due to their comfortable fit, excellent stability, natural appearance, and impressive track record in clinical settings. However, challenges such as potential issues with osseointegration, peri-implant bone loss, and peri-implantitis might lead to implant failure, causing concern for patients and dental staff. Surface modification has the potential to significantly enhance the success rate of titanium implants and meet the needs of clinical applications. This involves the application of various physical, chemical, and bioactive coatings, as well as adjustments to implant surface topography, offering significant potential for enhancing implant outcomes in terms of osseointegration and antimicrobial properties. Many surface modification methods have been employed to improve titanium implants, showcasing the diversity of approaches in this field including sandblasting, acid etching, plasma spraying, plasma immersion ion implantation, physical vapor deposition, electrophoretic deposition, electrochemical deposition, anodization, microarc oxidation, laser treatments, sol-gel method, layer-by-layer self-assembly technology, and the adsorption of biomolecules. This article provides a comprehensive overview of the surface modification methods for titanium implants to address issues with insufficient osseointegration and implant-related infections. It encompasses the physical, chemical, and biological aspects of these methods to provide researchers and dental professionals with a robust resource to aid them in their study and practical use of dental implant materials, ensuring they are thoroughly knowledgeable and well-prepared for their endeavors.

Potential of Graphene-Functionalized Polymer Surfaces for Dental Applications: A Systematic review

Graphene, a two-dimensional carbon nanomaterial, has garnered widespread attention across various fields due to its outstanding properties. In dental implantology, researchers are exploring the use of graphene-functionalized polymer surfaces to enhance both the osseointegration process and the long-term success of dental implants. This review consolidates evidence from in-vivo and in-vitro studies, highlighting graphene's capacity to improve bone-to-implant contact, exhibit antibacterial properties, and enhance mechanical strength. This research investigates the effects of incorporating graphene derivatives into polymer materials on tissue response and compatibility. Among 123 search results, 14 articles meeting the predefined criteria were analyzed. The study primarily focuses on assessing the impact of GO and rGO on cellular function and stability in implants. Results indicate promising improvements in cellular function and stability with the use of GO-coated or composited implants. However, it is noted that interactions between Graphene derivatives and polymers may alter the inherent properties of the materials. Therefore, further rigorous research is deemed imperative to fully elucidate their potential in human applications. Such comprehensive understanding is essential for unlocking the extensive benefits associated with the utilization of Graphene derivatives in biomedical contexts.

Microbial corrosion of metallic biomaterials in the oral environment

A wide variety of microorganisms have been closely linked to metal corrosion in the form of adherent surface biofilms. Biofilms allow the development and maintenance of locally corrosive environments and/or permit direct corrosion including pitting corrosion. The presence of numerous genetically distinct microorganisms in the oral environment poses a threat to the integrity and durability of the surface of metallic prostheses and implants used in routine dentistry. However, the association between oral microorganisms and specific corrosion mechanisms is not clear. It is of practical importance to understand how microbial corrosion occurs and the associated risks to metallic materials in the oral environment. This knowledge is also important for researchers and clinicians who are increasingly concerned about the biological activity of the released corrosion products. Accordingly, the main goal was to comprehensively review the current literature regarding oral microbiologically influenced corrosion (MIC) including characteristics of biofilms and of the oral environment, MIC mechanisms, corrosion behavior in the presence of oral microorganisms and potentially mitigating technologies. Findings included that oral MIC has been ascribed mostly to aggressive metabolites secreted during microbial metabolism (metabolite-mediated MIC). However, from a thermodynamic point of view, extracellular electron transfer mechanisms (EET-MIC) through pili or electron transfer compounds cannot be ruled out. Various MIC mitigating methods have been demonstrated to be effective in short term, but long term evaluations are necessary before clinical applications can be considered. Currently most in-vitro studies fail to simulate the complexity of intraoral physiological conditions which may either reduce or exacerbate corrosion risk, which must be addressed in future studies. STATEMENT OF SIGNIFICANCE: A thorough analysis on literature regarding oral MIC (microbiologically influenced corrosion) of biomedical metallic materials has been carried out, including characteristics of oral environment, MIC mechanisms, corrosion behaviors in the presence of typical oral microorganisms and potential mitigating methods (materials design and surface design). There is currently a lack of mechanistic understanding of oral MIC which is very important not only to corrosion researchers but also to dentists and clinicians. This paper discusses the significance of biofilms from a biocorrosion perspective and summarizes several aspects of MIC mechanisms which could be caused by oral microorganisms. Oral MIC has been closely associated with not only the materials research but also the dental/clinical research fields in this work.

Characteristics of Si (C,N) Silicon Carbonitride Layers on the Surface of Ni-Cr Alloys Used in Dental Prosthetics

Chromium- and cobalt-based alloys, as well as chrome-nickel steels, are most used in dental prosthetics. Unfortunately, these alloys, especially nickel-based alloys, can cause allergic reactions. A disadvantage of these alloys is also insufficient corrosion resistance. To improve the properties of these alloys, amorphous Si (C,N) coatings were deposited on the surfaces of metal specimens. This paper characterizes coatings of silicon carbide nitrides, deposited by the magnetron sputtering method on the surface of nickel-chromium alloys used in dental prosthetics. Depending on the deposition parameters, coatings with varying carbon to nitrogen ratios were obtained. The study analyzed their structure and chemical and phase composition. In addition, a study of surface wettability and surface roughness was performed. Based on the results obtained, it was found that amorphous coatings of Si (C,N) type with thicknesses of 2 to 4.5 µm were obtained. All obtained coatings increase the value of surface free energy. The study showed that Si (C,N)-type films can be used in dental prosthetics as protective coatings.

Biomaterials science and surface engineering strategies for dental peri-implantitis management

Peri-implantitis is a bacterial infection that causes soft tissue inflammatory lesions and alveolar bone resorption, ultimately resulting in implant failure. Dental implants for clinical use barely have antibacterial properties, and bacterial colonization and biofilm formation on the dental implants are major causes of peri-implantitis. Treatment strategies such as mechanical debridement and antibiotic therapy have been used to remove dental plaque. However, it is particularly important to prevent the occurrence of peri-implantitis rather than treatment. Therefore, the current research spot has focused on improving the antibacterial properties of dental implants, such as the construction of specific micro-nano surface texture, the introduction of diverse functional coatings, or the application of materials with intrinsic antibacterial properties. The aforementioned antibacterial surfaces can be incorporated with bioactive molecules, metallic nanoparticles, or other functional components to further enhance the osteogenic properties and accelerate the healing process. In this review, we summarize the recent developments in biomaterial science and the modification strategies applied to dental implants to inhibit biofilm formation and facilitate bone-implant integration. Furthermore, we summarized the obstacles existing in the process of laboratory research to reach the clinic products, and propose corresponding directions for future developments and research perspectives, so that to provide insights into the rational design and construction of dental implants with the aim to balance antibacterial efficacy, biological safety, and osteogenic property.

The potential use of nanozymes as an antibacterial agents in oral infection, periodontitis, and peri-implantitis

Several studies suggest that oral pathogenic biofilms cause persistent oral infections. Among these is periodontitis, a prevalent condition brought on by plaque biofilm. It can even result in tooth loss. Furthermore, the accumulation of germs around a dental implant may lead to peri-implantitis, which damages the surrounding bone and gum tissue. Furthermore, bacterial biofilm contamination on the implant causes soft tissue irritation and adjacent bone resorption, severely compromising dental health. On decontaminated implant surfaces, however, re-osseointegration cannot be induced by standard biofilm removal techniques such as mechanical cleaning and antiseptic treatment. A family of nanoparticles known as nanozymes (NZs) comprise highly catalytically active multivalent metal components. The most often employed NZs with antibacterial activity are those that have peroxidase (POD) activity, among other types of NZs. Since NZs are less expensive, more easily produced, and more stable than natural enzymes, they hold great promise for use in various applications, including treating microbial infections. NZs have significantly contributed to studying implant success rates and periodontal health maintenance in periodontics and implantology. An extensive analysis of the research on various NZs and their applications in managing oral health conditions, including dental caries, dental pulp disorders, oral ulcers, peri-implantitis, and bacterial infections of the mouth. To combat bacteria, this review concentrates on NZs that imitate the activity of enzymes in implantology and periodontology. With a view to the future, there are several ways that NZs might be used to treat dental disorders antibacterially.

Biomimetic Coatings in Implant Dentistry: A Quick Update

Biomimetic dental implants are regarded as one of the recent clinical advancements in implant surface modification. Coatings with varying thicknesses and roughness may affect the dental implant surface's chemical inertness, cell adhesion, and antibacterial characteristics. Different surface coatings and mechanical surface changes have been studied to improve osseointegration and decrease peri-implantitis. The surface medication increases surface energy, leading to enhanced cell proliferation and growth factors, and, consequently, to a rise in the osseointegration process. This review provides a comprehensive update on the numerous biomimetic coatings used to improve the surface characteristics of dental implants and their applications in two main categories: coating to improve osseointegration, including the hydroxyapatite layer and nanocomposites, growth factors (BMPs, PDGF, FGF), and extracellular matrix (collagen, elastin, fibronectin, chondroitin sulfate, hyaluronan, and other proteoglycans), and coatings for anti-bacterial performance, covering drug-coated dental implants (antibiotic, statin, and bisphosphonate), antimicrobial peptide coating (GL13K and human beta defensins), polysaccharide antibacterial coatings (natural chitosan and its coupling agents) and metal elements (silver, zinc, and copper).

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.

Resorbable GBR Scaffolds in Oral and Maxillofacial Tissue Engineering: Design, Fabrication, and Applications

Guided bone regeneration (GBR) is a promising technique in bone tissue engineering that aims to replace lost or injured bone using resorbable scaffolds. The promotion of osteoblast adhesion, migration, and proliferation is greatly aided by GBR materials, and surface changes are critical in imitating the natural bone structure to improve cellular responses. Moreover, the interactions between bioresponsive scaffolds, growth factors (GFs), immune cells, and stromal progenitor cells are essential in promoting bone regeneration. This literature review comprehensively discusses various aspects of resorbable scaffolds in bone tissue engineering, encompassing scaffold design, materials, fabrication techniques, and advanced manufacturing methods, including three-dimensional printing. In addition, this review explores surface modifications to replicate native bone structures and their impact on cellular responses. Moreover, the mechanisms of bone regeneration are described, providing information on how immune cells, GFs, and bioresponsive scaffolds orchestrate tissue healing. Practical applications in clinical settings are presented to underscore the importance of these principles in promoting tissue integration, healing, and regeneration. Furthermore, this literature review delves into emerging areas of metamaterials and artificial intelligence applications in tissue engineering and regenerative medicine. These interdisciplinary approaches hold immense promise for furthering bone tissue engineering and improving therapeutic outcomes, leading to enhanced patient well-being. The potential of combining material science, advanced manufacturing, and cellular biology is showcased as a pathway to advance bone tissue engineering, addressing a variety of clinical needs and challenges. By providing this comprehensive narrative, a detailed, up-to-date account of resorbable scaffolds' role in bone tissue engineering and their transformative potential is offered.

Environment-Responsive Therapeutic Platforms for the Treatment of Implant Infection

The application of medical implants has greatly improved the survival rate and life quality of patients. Nevertheless, in recent years, there are increasing cases of implant dysfunction or failure because of bacterial infections. Despite significant improvements in biomedicine, there are still serious challenges in the treatment of implant-related infections. With the formation of bacterial biofilms and the development of bacterial resistance, these limitations lead to a low efficacy of conventional antibiotics. To address these challenges, it is urgent to exploit innovative treatment strategies for implant-related infections. Based on these ideas, environment-responsive therapeutic platforms with high selectivity, low drug resistance, and minor dose-limiting toxicity have attracted widespread attention. By using exogenous/endogenous stimuli, the antibacterial activity of therapeutics can be activated on demand and exhibit remarkable therapeutic effects. Exogenous stimuli include photo, magnetism, microwave, and ultrasound. Endogenous stimuli mainly include the pathological characteristics of bacterial infections such as acidic pH, anomalous temperature, and abnormal enzymatic activities. In this review, the recent progress of environment-responsive therapeutic platforms with spatiotemporally controlled drug release/activation is systematically summarized. Afterward, the limitations and opportunities of these emerging platforms are highlighted. Finally, it is hoped that this review will offer novel ideas and techniques to combat implant-related infections.

Properties of SiCN Films Relevant to Dental Implant Applications

The application of surface coatings is a popular technique to improve the performance of materials used for medical and dental implants. Ternary silicon carbon nitride (SiCN), obtained by introducing nitrogen into SiC, has attracted significant interest due to its potential advantages. This study investigated the properties of SiCN films deposited via PECVD for dental implant coatings. Chemical composition, optical, and tribological properties were analyzed by adjusting the gas flow rates of NH3, CH4, and SiH4. The results indicated that an increase in the NH3 flow rate led to higher deposition rates, scaling from 5.7 nm/min at an NH3 flow rate of 2 sccm to 7 nm/min at an NH3 flow rate of 8 sccm. Concurrently, the formation of N-Si bonds was observed. The films with a higher nitrogen content exhibited lower refractive indices, diminishing from 2.5 to 2.3 as the NH3 flow rate increased from 2 sccm to 8 sccm. The contact angle of SiCN films had minimal differences, while the corrosion rate was dependent on the pH of the environment. These findings contribute to a better understanding of the properties and potential applications of SiCN films for use in dental implants.

Nanotherapeutics with immunoregulatory functions for the treatment of bacterial infection

The advent of drug-resistant pathogens results in the occurrence of stubborn bacterial infections that cannot be treated with traditional antibiotics. Antibacterial immunotherapy by reviving or activating the body's immune system to eliminate pathogenic bacteria has confirmed promising therapeutic strategies in controlling bacterial infections. Subsequent studies found that antimicrobial immunotherapy has its own benefits and limitations, such as avoiding recurrence of infection and autoimmunity-induced side effects. Current studies indicate that the various antibacterial therapeutic strategies inducing immune regulation can achieve superior therapeutic efficacy compared with monotherapy alone. Therefore, summarizing the recent advances in nanomedicine with immunomodulatory functions for combating bacterial infections is necessary. Herein, we briefly introduce the crisis caused by drug-resistant bacteria and the opportunity for antibacterial immunotherapy. Then, immune-involved multimodal antibacterial therapy for the treatment of infectious diseases was systematically summarized. Finally, the prospects and challenges of immune-involved combinational therapy are discussed.

Chitosan hydrogel modified with lanthanum as a drug delivery system for epigallocatechin gallate: Investigation of hydrogel - drug interaction by FT-IR and Raman spectroscopy

In the presented work, chitosan hydrogel modified with lanthanum was obtained for the first time. The hydrogel was used as a carrier in the controlled release of epigallocatechin gallate. The work proved the effectiveness of drug sorption by hydrogel and controlled release in simulated body fluids. The drug was released slowly and in a controlled manner from the carrier. The research techniques used in this work (FT-IR spectroscopy and imaging, Raman spectroscopy, SEM/EDS) allowed to confirm the successful retention of EGCG on the hydrogel surface. On the basis of the EDS mapping, it was possible to confirm the even distribution of the lanthanum ions. Using FT-IR imaging, we verified that the drug was evenly distributed on the entire surface of the prepared material. The antifungal effectiveness of the material has been proven on several types of fungi. The research proved that the prepared material is capable of long-term release of the active substance and has antifungal properties. As a result, the prepared material can be successfully used as an implantable hydrogel or a coating in, e.g. titanium implants.

Visible-Light-Enhanced Antibacterial Activity of Silver and Copper Co-Doped Titania Formed on Titanium via Chemical and Thermal Treatments

Dental implants made of titanium (Ti) are used in dentistry, but peri-implantitis is a serious associated problem. Antibacterial and osteoconductive Ti dental implants may decrease the risk of peri-implantitis. In this study, titania (TiO₂) co-doped with silver (Ag) at 2.5 at.% and copper (Cu) at 4.9 at.% was formed on Ti substrates via chemical and thermal treatments. The Ag and Cu co-doped TiO₂ formed apatite in a simulated body fluid, which suggests osteoconductivity. It also showed antibacterial activity against Escherichia coli, which was enhanced by visible-light irradiation. This enhancement might be caused by the synergistic effect of the release of Ag and Cu and the generation of •OH from the sample. Dental implants with such a Ag and Cu co-doped TiO₂ formed on their surface may reduce the risk of peri-implantitis.

The race for the optimal antimicrobial surface: perspectives and challenges related to plasma electrolytic oxidation coating for titanium-based implants

Plasma electrolytic oxidation (PEO) is a low-cost, structurally reliable, and environmentally friendly surface modification method for orthopedic and dental implants. This technique is successful for the formation of porous, corrosion-resistant, and bioactive coatings, besides introducing antimicrobial compounds easily. Given the increase in implant-related infections, antimicrobial PEO-treated surfaces have been widely proposed to surmount this public health concern. This review comprehensively discusses antimicrobial implant surfaces currently produced by PEO in terms of their in vitro and in vivo microbiological and biological properties. We present a critical [part I] and evidence-based [part II] review about the plethora of antimicrobial PEO-treated surfaces. The mechanism of microbial accumulation on implanted devices and the principles of PEO technology to ensure antimicrobial functionalization by one- or multi-step processes are outlined. Our systematic literature search showed that particular focus has been placed on the metallic and semi-metallic elements incorporated into PEO surfaces to facilitate antimicrobial properties, which are often dose-dependent, without leading to cytotoxicity in vitro. Meanwhile, there are concerns over the biocompatibility of PEO and its long-term antimicrobial effects in animal models. We clearly highlight the importance of using clinically relevant infection models and in vivo long-term assessments to guarantee the rational design of antimicrobial PEO-treated surfaces to identify the 'finish line' in the race for antimicrobial implant surfaces.

Preventing Peri-implantitis: The Quest for a Next Generation of Titanium Dental Implants

Titanium and its alloys are frequently the biomaterial of choice for dental implant applications. Although titanium dental implants have been utilized for decades, there are yet unresolved issues pertaining to implant failure. Dental implant failure can arise either through wear and fatigue of the implant itself or peri-implant disease and subsequent host inflammation. In the present report, we provide a comprehensive review of titanium and its alloys in the context of dental implant material, and how surface properties influence the rate of bacterial colonization and peri-implant disease. Details are provided on the various periodontal pathogens implicated in peri-implantitis, their adhesive behavior, and how this relationship is governed by the implant surface properties. Issues of osteointegration and immunomodulation are also discussed in relation to titanium dental implants. Some impediments in the commercial translation for a novel titanium-based dental implant from "bench to bedside" are discussed. Numerous in vitro studies on novel materials, processing techniques, and methodologies performed on dental implants have been highlighted. The present report review that comprehensively compares the in vitro, in vivo, and clinical studies of titanium and its alloys for dental implants.

Bioactive Inorganic Materials for Dental Applications: A Narrative Review

Over time, much attention has been given to the use of bioceramics for biomedical applications; however, the recent trend has been gaining traction to apply these materials for dental restorations. The bioceramics (mainly bioactive) are exceptionally biocompatible and possess excellent bioactive and biological properties due to their similar chemical composition to human hard tissues. However, concern has been noticed related to their mechanical properties. All dental materials based on bioactive materials must be biocompatible, long-lasting, mechanically strong enough to bear the masticatory and functional load, wear-resistant, easily manipulated, and implanted. This review article presents the basic structure, properties, and dental applications of different bioactive materials i.e., amorphous calcium phosphate, hydroxyapatite, tri-calcium phosphate, mono-calcium phosphate, calcium silicate, and bioactive glass. The advantageous properties and limitations of these materials are also discussed. In the end, future directions and proposals are given to improve the physical and mechanical properties of bioactive materials-based dental materials.

Finite Element Analysis of Zirconia Dental Implant

Titanium dental implants have had new competitors in recent years, such as fixtures made of zirconia, which promise better aesthetics. The purpose of this study is to evaluate their mechanical performance in silico (Finite Element Analysis). The investigation was performed on a single tooth Patent™ Dental Implant (Zircon Medical®, Altendorf, Switzerland) in two configurations: without offset (Test I) and with offset (Test II, 1.5 mm within the cortical bone). The Patent Implant system consists of two components: the implant with integrated abutment and the fibreglass post. The components of the dental implants were tested using a compression load of 400 N along the implant axis. The results showed that the chewing load generates stress distribution on the bone, therefore, the offset configuration should be avoided.

Photocatalytic Cu2WS4 Nanocrystals for Efficient Bacterial Killing and Biofilm Disruption

Background

Bacterial biofilm-related wound infections threaten human health due to the lack of efficient treatments. Therefore, developing a novel strategy for wound infection care is urgently needed.

Methods

Cube-shaped Cu₂WS₄ nanocrystals (CWSNs) were successfully prepared via a microwave-assisted method. CWSNs, as photocatalysts, were first studied by using fluorescence spectroscopy for their ability to generate reactive oxygen species (ROS). The antibacterial and biofilm inhibition abilities of CWSNs were determined in vitro by using Staphylococcus aureus (S.aureus) as the model bacterium. Moreover, a CWSN gel was prepared and applied to treat S. aureus-infected wounds in mice. The toxicity of the CWSNs was evaluated through in vitro cell and in vivo animal experiments.

Results

Studies on the properties of the CWSNs demonstrated that these nanomaterials can catalyze the generation of hydroxyl radicals (•OH) without the addition of H₂O₂ after visible-light irradiation, indicating their photocatalytic ability. Moreover, the in vitro experimental results showed that the CWSNs not only adhered to the surfaces of S. aureus to kill the bacteria, but also inhibited S. aureus biofilm formation. The in vivo study showed that the CWSN gel produced excellent antibacterial effects against S. aureus infected wounds in mice and effectively promoted wound healing. Furthermore, toxicity tests showed that the CWSNs have negligible toxicity in vitro and in vivo.

Conclusion

This work provides a potential photocatalytic antibacterial nanoagent for efficient bacterial killing, inhibition of biofilms growth and wound infection treatment.

Latest Trends in Surface Modification for Dental Implantology: Innovative Developments and Analytical Applications

An increase in the world population and its life expectancy, as well as the ongoing concern about our physical appearance, have elevated the relevance of dental implantology in recent decades. Engineering strategies to improve the survival rate of dental implants have been widely investigated, focusing on implant material composition, geometry (usually guided to reduce stiffness), and interface surrounding tissues. Although efforts to develop different implant surface modifications are being applied in commercial dental prostheses today, the inclusion of surface coatings has gained special interest, as they can be tailored to efficiently enhance osseointegration, as well as to reduce bacterial-related infection, minimizing peri-implantitis appearance and its associated risks. The use of biomaterials to replace teeth has highlighted the need for the development of reliable analytical methods to assess the therapeutic benefits of implants. This literature review considers the state-of-the-art strategies for surface modification or coating and analytical methodologies for increasing the survival rate for teeth restoration.

Therapeutic Applications of Antimicrobial Silver-Based Biomaterials in Dentistry

Microbial infection accounts for many dental diseases and treatment failure. Therefore, the antibacterial properties of dental biomaterials are of great importance to the long-term results of treatment. Silver-based biomaterials (AgBMs) have been widely researched as antimicrobial materials with high efficiency and relatively low toxicity. AgBMs have a broad spectrum of antimicrobial properties, including penetration of microbial cell membranes, damage to genetic material, contact killing, and dysfunction of bacterial proteins and enzymes. In particular, advances in nanotechnology have improved the application value of AgBMs. Hence, in many subspecialties of dentistry, AgBMs have been researched and employed, such as caries arresting or prevention, root canal sterilization, periodontal plaque inhibition, additives in dentures, coating of implants and anti-inflammatory material in oral and maxillofacial surgery. This paper aims to provide an overview of the application approaches of AgBMs in dentistry and present better guidance for oral antimicrobial therapy via the development of AgBMs.

Superhydrophilic multifunctional nanotextured titanium dental implants: in vivo short and long-term response in a porcine model

Current clinical demand in dental implantology is for a multifunctional device with optimum mechanical properties, improved biocompatibility and bioactivity, and having differential interactions with cells and pathogenic agents. This would minimise bacterial infection, biofilm formation and modulate inflammation, leading to a fast and durable osseointegration. The present study intends to establish the multifunctional behaviour of surface modified titanium dental implants that are superhydrophilic, with unique micro-nano or nanoscale topographies, developed by a facile hydrothermal technique. Here, the short and long-term performances of these textured implants are tested in a split mouth design using a porcine model, in pre- and post-loaded states. Quantitative and qualitative analyses of the bone implant interphase are performed through μ-CT and histology. Parameters that evaluate bone mineral density, bone contact volume and bone implant contact reveal enhanced bone apposition with better long-term response for the nano and micro-nano textured surfaces, compared to the commercial microtextured implant. Concurrently, the nanoscale surface features on implants reduced bacterial attachment by nearly 90% in vivo, outperforming the commercial variant. This preclinical evaluation data thus reveal the superiority of nano/micro-nano textured designs for clinical application and substantiate their improved osseointegration and reduced bacterial adhesion, thus proposing a novel dental implant with multifunctional characteristics.

Mechanical properties and in vitro cytocompatibility of dense and porous Ti-6Al-4V ELI manufactured by selective laser melting technology for biomedical applications

The Ti-6Al-4V alloy is the most common biomaterial used for bone replacements and reconstructions. Despite its advantages, the Ti-6Al-4V has a high stiffness that can cause stress-shielding. In this work, we demonstrated that the selective laser melting (SLM) technology could be used to fabricate porosity in Ti-6Al-4V extra low interstitial (ELI) to reduce its stiffness while improving cell adhesion and proliferation. With a porosity of 14.04%, the elastic modulus of the porous Ti-6Al-4V ELI was reduced to 80 GPa. The compressive stress and the 3-point-bending flexural tests revealed that the porous Ti-6Al-4V ELI possessed a brittle characteristic. The additional pores within the beams of the lattice structures of porous Ti-6Al-4V ELI increased its surface arithmetic average roughness, R_a = 3.94 μm. The in vitro cytocompatibility test showed that the SLM printing process and the post-processes did not cause any toxicity in the MC3T3-E1 cells. The in vitro cell proliferation test also showed that the porous Ti-6Al-4V ELI increased the proliferation rate of osteogenic induced MC3T3-E1 cells on Day 7. The findings from this study would provide engineers and researchers with both the mechanical information and biological understanding of SLM printed porous Ti-6Al-4V ELI, and SLM printed dense Ti-6Al-4V ELI towards biomedical applications.

Surface Treatment of the Dental Implant with Hyaluronic Acid: An Overview of Recent Data

Recently, interest has grown by focusing on the evaluation of a molecule already produced in the human body such as hyaluronic acid (HA), as an application to the surface of the titanium implant. Its osteo-conductive characteristics and positive interaction with the progenitor cells responsible for bone formation, consequently, make it responsible for secondary stability. The aim of this work was to analyze the various surface treatments in titanium implants, demonstrating that the topography and surface chemistry of biomaterials can correlate with the host response; also focusing on the addition of HA to the implant surface and assessing the biological implications during early stages of recovery. Used as a coating, HA acts on the migration, adhesion, proliferation and differentiation of cell precursors on titanium implants by improving the connection between implant and bone. Furthermore, the improvement of the bioactivity of the implant surfaces through HA could therefore facilitate the positioning of the dental prosthesis precisely in the early loading phase, thus satisfying the patients’ requests. It is important to note that all the findings should be supported by further experimental studies in animals as well as humans to evaluate and confirm the use of HA in any field of dentistry.

Titanium-Based Alloy Surface Modification with TiO2 and Poly(sodium 4-styrenesulfonate) Multilayers for Dental Implants

Implant placement is an important repair method in dentistry and orthopedics. Increasing efforts have focused on optimizing the biocompatibility and osseointegration properties of titanium (Ti) and Ti-based alloys. In this work, Ti-based alloys were modified by the layer-by-layer (LbL) technique, which is a simple and versatile method for surface modification. The morphology and chemical structure of LbL films of poly(sodium 4-styrenesulfonate) (PSS) and Ti dioxide (TiO₂) nanoparticles were first characterized employing ultraviolet-visible and Fourier-transform infrared spectroscopies as well as atomic force microscopy for further application in Ti-based alloy implants. The changes provoked by the LbL PSS/TiO₂ film on the Ti-based alloy surfaces were then investigated by scanning electron microscopy and micro-Raman techniques. Finally, in vivo tests (immunolabeling and biomechanical analysis) performed with screw implants in rats suggested that PSS/TiO₂ multilayers promote changes in both topography and chemical surface properties of the screw, providing beneficial effects for osteoblast activity. This simple and relatively low-cost growth process can open up possibilities to improve dental implants and, probably, bone implants in general.

Synthesis and Characterization of Polymer-Based Coatings Modified with Bioactive Ceramic and Bovine Serum Albumin

This study involves the synthesis of hydroxyapatite and describes the preparation and characterization of polymer coatings based on poly(ethylene glycol) diacrylate and poly(ethylene glycol) and modified with bovine serum albumin and hydroxyapatite. Hydroxyapatite was obtained by wet chemical synthesis and characterized by X-ray diffraction and FTIR spectroscopy, and its Ca/P molar ratio was determined (1.69 ± 0.08). The ceramic and bovine serum albumin were used in the preparation of composite materials with the polymeric matrix. The chemical composition of coatings was characterized with FTIR spectroscopy, and their morphology was recorded with SEM imaging. Moreover, the measurements of surface roughness parameters and stereometric research were performed. The prepared coatings were subjected to in vitro studies in simulated body fluid and artificial saliva. Changes in chemical composition and morphology after immersion were examined with FTIR spectroscopy and SEM imaging. Based on the conducted research, it can be stated that applied modifiers promote the biomineralization process. The roughness analysis confirmed prepared materials were characterized by the micrometer-scale topography. The materials morphology and roughness, and the morphology of the newly formed apatite deposit, were dependent on the type of the used modifier, and the artificial fluid used in in vitro studies.

Electrosprayed calcium silicate nanoparticle-coated titanium implant with improved antibacterial activity and osteogenesis

To ensure clinical success, the implant and the surrounding bone tissue must not only be integrated, but also must not be suspected of infection. In this work, an antibacterial and bioactive nanostructured calcium silicate (CaSi) layer on titanium substrate by an electrospray deposition method was prepared, followed by annealing at 700, 750 and 800 °C to improve the bonding strength of the CaSi coating. The phase composition, microstructure and bonding strength of the CaSi coatings were examined. Human mesenchymal stem cells (hMSCs), Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) species were used to analyze the osteogenic and antibacterial activity of the coatings, respectively. Experimental results showed that the as-prepared CaSi coating was mainly composted of β-dicalcium silicate phase with a particle size of about 300 nm. After annealing, the thickness of the oxidation reaction layer increased obviously from 0.3 μm to 1 μm with increase in temperature, which was confirmed by the cross-sectional morphology and element depth profile. The bonding strength of the coating annealed at 750 °C (19.0 MPa) was significantly higher (p < 0.05) than that of the as-prepared coating (4.4 MPa) and the ISO 13,779 standard (15 MPa). The results of antibacterial efficacy and stem cell osteogenesis consistently elaborated that the 750 °C-annealed coating had higher activity than the as-prepared coating and the Ti control. It is concluded that after annealing at 750 °C, the CaSi nanoparticle-coated Ti implant had good bond strength, osteogenic and antibacterial activity.

Calcium Phosphate Modified with Silicon vs. Bovine Hydroxyapatite for Alveolar Ridge Preservation: Densitometric Evaluation, Morphological Changes and Histomorphometric Study

After tooth extraction, the alveolar bone undergoes a physiological resorption that may compromise the future placement of the implant in its ideal position. This study evaluated bone density, morphological changes, and histomorphometric results undergone by alveolar bone after applying a new biomaterial composed of calcium phosphate modified with silicon (CAPO-Si) compared with hydroxyapatite of bovine origin (BHA). Alveolar ridge preservation (ARP) was performed in 24 alveoli, divided into a test group filled with CAPO-Si and a control group filled with BHA. Three months later, the mineral bone density obtained by the biomaterials, horizontal and vertical bone loss, the degree of alveolar corticalization, and histomorphometric results were evaluated. Both biomaterials presented similar behavior in terms of densitometric results, vertical bone loss, and degree of alveolar corticalization. Alveoli treated with CAPO-Si showed less horizontal bone loss in comparison with alveoli treated with BHA (0.99 ± 0.2 mm vs. 1.3 ± 0.3 mm), with statistically significant difference (p = 0.017). Histomorphometric results showed greater bone neoformation in the test group than the control group (23 ± 15% vs. 11 ± 7%) (p = 0.039) and less residual biomaterial (5 ± 10% vs. 17 ± 13%) (p = 0.043) with statistically significant differences. In conclusion, the ARP technique obtains better results with CAPO-Si than with BHA.

Modulation of immune-inflammatory responses through surface modifications of biomaterials to promote bone healing and regeneration

Control of inflammation is indispensable for optimal oral wound healing and tissue regeneration. Several biomaterials have been used to enhance the regenerative outcomes; however, the biomaterial implantation can ensure an immune-inflammatory response. The interface between the cells and the biomaterial surface plays a critical role in determining the success of soft and hard tissue regeneration. The initial inflammatory response upon biomaterial implantation helps in tissue repair and regeneration, however, persistant inflammation impairs the wound healing response. The cells interact with the biomaterials through extracellular matrix proteins leading to protein adsorption followed by recruitment, attachment, migration, and proliferation of several immune-inflammatory cells. Physical nanotopography of biomaterials, such as surface proteins, roughness, and porosity, is crucial for driving cellular attachment and migration. Similarly, modification of scaffold surface chemistry by adapting hydrophilicity, surface charge, surface coatings, can down-regulate the initiation of pro-inflammatory cascades. Besides, functionalization of scaffold surfaces with active biological molecules can down-regulate pro-inflammatory and pro-resorptive mediators' release as well as actively up-regulate anti-inflammatory markers. This review encompasses various strategies for the optimization of physical, chemical, and biological properties of biomaterial and the underlying mechanisms to modulate the immune-inflammatory response, thereby, promoting the tissue integration and subsequent soft and hard tissue regeneration potential of the administered biomaterial.