Tetracycline-incorporated polymer nanofibers as a potential dental implant surface modifier

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.

Next-generation antibacterial nanopolymers for treating oral chronic inflammatory diseases of bacterial origin

BACKGROUND

'Periodontitis' refers to periodontal destruction of connective tissue attachment and bone, in response to microorganisms forming subgingival biofilms on the root surface, while 'apical periodontitis' refers to periapical inflammatory processes occurring in response to microorganisms within the root canal system. The treatment of both diseases is based on the elimination of the bacterial challenge, though its predictability depends on the ability of disrupting these biofilms, what may need adjunctive antibacterial strategies, such as the next-generation antibacterial strategies (NGAS). From all the newly developed NGAS, the use of polymeric nanotechnology may pose a potential effective approach. Although some of these strategies have only been tested in vitro and in preclinical in vivo models, their use holds a great potential, and therefore, it is relevant to understand their mechanism of action and evaluate their scientific evidence of efficacy.

OBJECTIVES

To explore NGAS based on polymeric nanotechnology used for the potential treatment of periodontitis and apical periodontitis.

METHOD

A systemic search of scientific publications of adjunctive antimicrobial strategies using nanopolymers to treat periodontal and periapical diseases was conducted using The National Library of Medicine (MEDLINE by PubMed), The Cochrane Oral Health Group Trials Register, EMBASE and Web of Science.

RESULTS

Different polymeric nanoparticles, nanofibres and nanostructured hydrogels combined with antimicrobial substances have been identified in the periodontal literature, being the most commonly used nanopolymers of polycaprolactone, poly(lactic-co-glycolic acid) and chitosan. As antimicrobials, the most frequently used have been antibiotics, though other antimicrobial substances, such as metallic ions, peptides and naturally derived products, have also been added to the nanopolymers.

CONCLUSION

Polymeric nanomaterials containing antimicrobial compounds may be considered as a potential NGAS. Its relative efficacy, however, is not well understood since most of the existing evidence is derived from in vitro or preclinical in vivo studies.

Nano-scaled surfaces and sustainable-antibiotic-release from polymeric coating for application on intra-osseous implants and trans-mucosal abutments

Multifunctional surfaces may display the potential to accelerate and promote the healing process around dental implants. However, the initial cellular biocompatibility, molecular activity, and the release of functionalized molecules from these novel surfaces require extensive investigation for clinical use. Aiming to develop and compare innovative surfaces for application in dental implants, the present study utilized titanium disks, which were treated and divided into four groups: machined (Macro); acid-etched (Micro); anodized-hydrophilic surface (TNTs); and anodized surface coated with a rifampicin-loaded polymeric layer (poly(lactide-co-glycolide), PLGA) (TNTsRIMP). The samples were characterized regarding their physicochemical properties and the cumulative release of rifampicin (RIMP), investigated at different pH values. Additionally, differentiated osteoblasts from mesenchymal cells were used for cell viability and qRT-PCR analysis. Antibacterial properties of each surface treatment were investigated against Staphylococcus epidermidis. TNTsRIMP demonstrated controlled drug release for up to 7 days in neutral pH environments. Osteogenic cell cultures indicated that all the evaluated surfaces showed biocompatibility. The TNTs group revealed up-regulated values for bone-related gene quantification in 7 days, followed by the TNTsRIMP group. Furthermore, the antibiotic-functionalized surface revealed effectiveness to inhibit S. epidermidis and stimulate promising conditions for osteogenic cell behavior. Characteristics such as nanomorphology and hydrophilicity were determinants for the up-regulated quantification of osteogenic biomarkers related to early bone maturation, encouraging application in intra-osseous implant surfaces; in addition, antibiotic-functionalized surfaces demonstrated significant higher antibacterial properties compared to the other groups. Our findings suggest that polymeric-antibiotic-loaded coating might be applied for the prevention of early infections, favoring its application in multifunctional surfaces for intra- and/or trans-mucosal components of dental implants, while, hydrophilic nanotextured surfaces promoted optimistic properties to stimulate early bone-related cell responses, favoring its application in bone-anchored surfaces.

Important Roles and Potential Uses of Natural and Synthetic Antimicrobial Peptides (AMPs) in Oral Diseases: Cavity, Periodontal Disease, and Thrush

Numerous epithelial cells and sometimes leukocytes release AMPs as their first line of defense. AMPs encompass cationic histatins, defensins, and cathelicidin to encounter oral pathogens with minimal resistance. However, their concentrations are significantly below the effective levels and AMPs are unstable under physiological conditions due to proteolysis, acid hydrolysis, and salt effects. In parallel to a search for more effective AMPs from natural sources, considerable efforts have focused on synthetic stable and low-cytotoxicy AMPs with significant activities against microorganisms. Using natural AMP templates, various attempts have been used to synthesize sAMPs with different charges, hydrophobicity, chain length, amino acid sequence, and amphipathicity. Thus far, sAMPs have been designed to target Streptococcus mutans and other common oral pathogens. Apart from sAMPs with antifungal activities against Candida albicans, future endeavors should focus on sAMPs with capabilities to promote remineralization and antibacterial adhesion. Delivery systems using nanomaterials and biomolecules are promising to stabilize, reduce cytotoxicity, and improve the antimicrobial activities of AMPs against oral pathogens. Nanostructured AMPs will soon become a viable alternative to antibiotics due to their antimicrobial mechanisms, broad-spectrum antimicrobial activity, low drug residue, and ease of synthesis and modification.

Recent Advances in Designing Fibrous Biomaterials for the Domain of Biomedical, Clinical, and Environmental Applications

Unique properties and potential applications of nanofibers have emerged as innovative approaches and opportunities in the biomedical, healthcare, environmental, and biosensor fields. Electrospinning and centrifugal spinning strategies have gained considerable attention among all kinds of strategies to produce nanofibers. These techniques produce nanofibers with high porosity and surface area, adequate pore architecture, and diverse chemical compositions. The extraordinary characteristics of nanofibers have unveiled new gates in nanomedicine to establish innovative fiber-based formulations for biomedical use, healthcare, and a wide range of other applications. The present review aims to provide a comprehensive overview of nanofibers and their broad range of applications, including drug delivery, biomedical scaffolds, tissue/bone-tissue engineering, dental applications, and environmental remediation in a single place. The review begins with a brief introduction followed by potential applications of nanofibers. Finally, the future perspectives and current challenges of nanofibers are demonstrated. This review will help researchers to engineer more efficient multifunctional nanofibers with improved characteristics for their effective use in broad areas. We strongly believe this review is a reader's delight and will help in dealing with the fundamental principles and applications of nanofiber-based scaffolds. This review will assist students and a broad range of scientific communities to understand the significance of nanofibers in several domains of nanotechnology, nanomedicine, biotechnology, and environmental remediation, which will set a benchmark for further research.

A Bibliometric Analysis of Electrospun Nanofibers for Dentistry

Electrospun nanofibers have been widely used in dentistry due to their excellent properties, such as high surface area and high porosity, this bibliometric study aimed to review the application fields, research status, and development trends of electrospun nanofibers in different fields of dentistry in recent years. All of the data were obtained from the Web of Science from 2004 to 2021. Origin, Microsoft Excel, VOSviewer, and Carrot² were used to process, analyze, and evaluate the publication year, countries/region, affiliations, authors, citations, keywords, and journal data. After being refined by the year of publication, document types and research fields, a total of 378 publications were included in this study, and an increasing number of publications was evident. Through linear regression calculations, it is predicted that the number of published articles in 2022 will be 66. The most published journal about electrospun dental materials is Materials Science & Engineering C-Materials for Biological Applications, among the six core journals identified, the percent of journals with Journal Citation Reports (JCR) Q1 was 60%. A total of 17.60% of the publications originated from China, and the most productive institution was the University of Sheffield. Among all the 1949 authors, the most productive author was Marco C. Bottino. Most electrospun dental nanofibers are used in periodontal regeneration, and Polycaprolactone (PCL) is the most frequently used material in all studies. With the global upsurge in research on electrospun dental materials, bone regeneration, tissue regeneration, and cell differentiation and proliferation will still be the research hotspots of electrospun dental materials in recent years. Extensive collaboration and citations among authors, institutions and countries will also reach a new level.

Novel Utilization of Therapeutic Coatings Based on Infiltrated Encapsulated Rose Bengal Microspheres in Porous Titanium for Implant Applications

Despite the increasing progress achieved in the last 20 years in both the fabrication of porous dental implants and the development of new biopolymers for targeting drug therapy, there are important issues such as bone resorption, poor osseointegration, and bacterial infections that remain as critical challenges to avoid clinical failure problems. In this work, we present a novel microtechnology based on polycaprolactone microspheres that can adhere to porous titanium implant models obtained by the spacer holder technique to allow a custom biomechanical and biofunctional balance. For this purpose, a double emulsion solvent evaporation technique was successfully employed for the fabrication of the microparticles properly loaded with the antibacterial therapeutic agent, rose bengal. The resulting microspheres were infiltrated into porous titanium substrate and sintered at 60 °C for 1 h, obtaining a convenient prophylactic network. In fact, the sintered polymeric microparticles were demonstrated to be key to controlling the drug dissolution rate and favoring the early healing process as consequence of a better wettability of the porous titanium substrate to promote calcium phosphate nucleation. Thus, this joint technology proposes a suitable prophylactic tool to prevent both early-stage infection and late-stage osseointegration problems.

Construction of Local Drug Delivery System on Titanium-Based Implants to Improve Osseointegration

Titanium and its alloys are the most widely applied orthopedic and dental implant materials due to their high biocompatibility, superior corrosion resistance, and outstanding mechanical properties. However, the lack of superior osseointegration remains the main obstacle to successful implantation. Previous traditional surface modification methods of titanium-based implants cannot fully meet the clinical needs of osseointegration. The construction of local drug delivery systems (e.g., antimicrobial drug delivery systems, anti-bone resorption drug delivery systems, etc.) on titanium-based implants has been proved to be an effective strategy to improve osseointegration. Meanwhile, these drug delivery systems can also be combined with traditional surface modification methods, such as anodic oxidation, acid etching, surface coating technology, etc., to achieve desirable and enhanced osseointegration. In this paper, we review the research progress of different local drug delivery systems using titanium-based implants and provide a theoretical basis for further research on drug delivery systems to promote bone–implant integration in the future.

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.

Novel cinnamon-laden nanofibers as a potential antifungal coating for poly(methyl methacrylate) denture base materials

OBJECTIVES

To modify the surface of denture base material by coating it with cinnamon-laden nanofibers to reduce Candida albicans (C. albicans) adhesion and/or proliferation.

MATERIALS AND METHODS

Heat-cured poly(methyl methacrylate) (PMMA) specimens were processed and coated, or not, with cinnamon-laden polymeric nanofibers (20 or 40 wt.% of cinnamon relative to the total polymer weight). Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses of the nanofibers were performed. Antifungal activity was assessed through agar diffusion and colony-forming unit (CFU/mL) assays. Representative SEM morphological analysis was carried out to observe the presence/absence of C. albicans on the fibers. Alamar blue assay was used to determine cell toxicity. Analysis of variance and the Tukey's test were used to analyze the data (α = 0.05).

RESULTS

SEM imaging revealed nanofibers with adequate (i.e., bead-free) morphological characteristics and uniform microstructure. FTIR confirmed cinnamon incorporation. The cinnamon-laden nanofibers led to growth inhibition of C. albicans. Viable fungal counts support a significant reduction on CFU/mL also directly related to cinnamon concentration (40 wt.%: mean log 6.17 CFU/mL < 20 wt.%: mean log 7.12 CFU/mL), which agrees with the SEM images. Cinnamon-laden nanofibers at 40 wt.% led to increased cell death.

CONCLUSIONS

The deposition of 20 wt.% cinnamon-laden nanofibers onto PMMA surfaces led to a significant reduction of the adhesive and/or proliferative ability of C. albicans, while maintaining epithelial cells' viability.

CLINICAL RELEVANCE

The high recurrence rates of denture stomatitis are associated with patient non-adherence to treatments and contaminated prostheses use. Here, we provide the non-patients' cooperation sensible method, which possesses antifungal action, hence improving treatment effectiveness.

Recent Advances in the Development of Antimicrobial and Antifouling Biocompatible Materials for Dental Applications

The risk of secondary bacterial infections resulting from dental procedures has driven the design of antimicrobial and antifouling dental materials to curb pathogenic microbial growth, biofilm formation and subsequent oral and dental diseases. Studies have investigated approaches based primarily on contact-killing or release-killing materials. These materials are designed for addition into dental resins, adhesives and fillings or as immobilized coatings on tooth surfaces, titanium implants and dental prosthetics. This review discusses the recent developments in the different classes of biomaterials for antimicrobial and antifouling dental applications: polymeric drug-releasing materials, polymeric and metallic nanoparticles, polymeric biocides and antimicrobial peptides. With modifications to improve cytotoxicity and mechanical properties, contact-killing and anti-adhesion materials show potential for incorporation into dental materials for long-term clinical use as opposed to short-lived antimicrobial release-based coatings. However, extended durations of biocompatibility testing, and adjustment of essential biomaterial features to enhance material longevity in the oral cavity require further investigations to confirm suitability and safety of these materials in the clinical setting. The continuous exposure of dental restorative and regenerative materials to pathogenic microbes necessitates the implementation of antimicrobial and antifouling materials to either replace antibiotics or improve its rational use, especially in the day and age of the ever-increasing problem of antimicrobial resistance.

Effect of the Addition of Alginate and/or Tetracycline on Brushite Cement Properties

Calcium phosphate cements have the advantage that they can be prepared as a paste that sets in a few minutes and can be easily adapted to the shape of the bone defect, which facilitates its clinical application. In this research, six formulations of brushite (dicalcium phosphate dihydrated) cement were obtained and the effect of the addition of sodium alginate was analyzed, such as its capacity as a tetracycline release system. The samples that contain sodium alginate set in 4 or 5 min and showed a high percentage of injectability (93%). The cements exhibit compression resistance values between 1.6 and 2.6 MPa. The drug was released in a range between 12.6 and 13.2% after 7 days. The antimicrobial activity of all the cements containing antibiotics was proven. All samples reached values of cell viability above 70 percent. We also observed that the addition of the sodium alginate and tetracycline improved the cell viability.

Current status and future of delivery systems for prevention and treatment of infections in the oral cavity

Oral health reflects the general health, and it is fundamental to well-being and quality of life. An infection in the oral cavity can be associated with serious complications in human health. Local therapy of these infections offers many advantages over systemic drug administration, targeting directly to the diseased area while minimizing systemic side effects. Specialized drug delivery systems into the oral cavity have to be designed in such a fashion that they resist to the aqueous environment that is constantly bathed in saliva and subject to mechanical forces. Additionally, a prolonged release of drug should also be provided, which would enhance the efficacy and also decrease the repeated dosing. This review is aimed to summarize the current most relevant findings related to local drug delivery of various drug groups for prevention and treatment of infections (viral, bacterial, fungal) and infection-related manifestations in the oral cavity. Current therapeutic challenges in regard to effective local drug delivery systems will be discussed, and the recent approaches to overcome these obstacles will be reviewed. Finally, future prospects will be overviewed to promote novel strategies that can be implemented in clinical management for prevention and treatment of oral infections.

Surface Modified Techniques and Emerging Functional Coating of Dental Implants

Dental implants are widely used in the field of oral restoration, but there are still problems leading to implant failures in clinical application, such as failed osseointegration, marginal bone resorption, and peri-implantitis, which restrict the success rate of dental implants and patient satisfaction. Poor osseointegration and bacterial infection are the most essential reasons resulting in implant failure. To improve the clinical outcomes of implants, many scholars devoted to modifying the surface of implants, especially to preparing different physical and chemical modifications to improve the osseointegration between alveolar bone and implant surface. Besides, the bioactive-coatings to promote the adhesion and colonization of ossteointegration-related proteins and cells also aim to improve the osseointegration. Meanwhile, improving the anti-bacterial performance of the implant surface can obstruct the adhesion and activity of bacteria, avoiding the occurrence of inflammation related to implants. Therefore, this review comprehensively investigates and summarizes the modifying or coating methods of implant surfaces, and analyzes the ossteointegration ability and anti-bacterial characteristics of emerging functional coatings in published references.

Bioactive Healing Abutment as a Potential Tool for the Treatment of Peri-Implant Disease—In Vitro Study

The common use of dental implants for dental reconstruction poses new treatment challenges for physicians, peri-implantitis being a particularly difficult one. Micro-organisms, including drug-resistant Staphylococcus spp. strains, play a crucial role in the etiology of peri-implantitis. In this paper, the authors assess the efficacy of a bioactive healing abutment (BHA) of their own design for the local release of antibiotics as a potential tool for the treatment of peri-implant disease. BHA filled with a collagen material, combined with the antibiotics clindamycin and tetracycline, was tested in vitro by disk diffusion assay. Antibacterial activity was observed for the chosen Staphylococcus aureus and Staphylococcus epidermidis bacterial strains. In addition, the impact of titanium discs (which were used to make the BHA) was monitored. The results show that the zone diameter breakpoints for BHA are higher than those of standard absorbent paper discs in both tested strains for both tested antibiotics. This work demonstrates that the proposed BHA can serve as an effective and precise drug carrier. The release of antibiotics from the described implant device is easy to control and allows for an effective local antibacterial in vitro treatment. The procedure is inexpensive, easy to perform, and repeatable.

Antibacterial Properties of Nano-Ag Coating on Healing Abutment: An In Vitro and Clinical Study

Peri-implantitis is an inflammatory disease with a relevant focus on the long-term success of dental implants and implant-supported prostheses. The present study focuses on the antibacterial effect of the silver nanoparticle and investigated the suppression of dental plaque adhesion on implant abutment and/or superstructure by micro-wave assistant nanosilver coating in vivo and in vitro. Nanosilver coating on pure titanium was prepared by microwave-assisted synthesis, and characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. In vitro studies were conducted to analyze biocompatibility using MTS assay and fluorescence microscopy with human gingival fibroblasts to evaluate antibacterial activity. During the in vivo study, nanosilver coating was applied to the healing abutments, and the prevention of plaque accumulation on nanosilver coating was confirmed by a split-mouth randomized clinical trial. The aggregation of nano-sized particles was found on the titanium surface with an antibacterial effect. The coating had no cytotoxic effect on human gingival fibroblasts. The result of the clinical trial showed that the coating suppressed the dental plaque adhesion on the healing abutments. Nanosilver coating is a promising material with antibacterial properties and can be used for implant abutments and prostheses for preventing peri-implantitis.

Nanofibers as drug-delivery systems for infection control in dentistry

INTRODUCTION

Due to the complexity of different oral infections, new anti-infective nanotechnological approaches have been emerging for dentistry in recent years. These strategies may contribute to antimicrobial molecules delivery, tissue regeneration, and oral health maintenance by acting in a more specific site and not being cytotoxic. In this context, nanofibers appear as versatile structures and might act both in the release of antimicrobial molecules and as a scaffold for new tissue formation.

AREAS COVERED

This review addresses the application of different nanofibers as new strategies for the delivery of antimicrobial molecules for dentistry. Here, we present the main polymers used to construct nanofibers, methods of production and mainly their antimicrobial activity against microorganisms commonly responsible for the usual dental infections. These biomaterials may be associated to restorative materials, prostheses, and mucoadhesive structures. Besides, nanofibers can be used for endodontic or periodontal therapy, or even on implant surfaces.

EXPERT OPINION

A wide variety of studies report the potential application of anti-infective nanofibers in the oral cavity. Although there are still several barriers between in vitro and in vivo studies, these new formulations appear as promising new therapies for dentistry.

Design of dental implants at materials level: An overview

Due to the excellent restoration of masticatory function, satisfaction on aesthetics and other superiorities, dental implants represent an effective method to resolve tooth losing and damaging. Current dental implant systems still have problems waiting to be addressed, and problems are centralized on the materials of implant bodies. This review aims to summarize major developments in the field of dental implant materials, starting with an overview on structures, procedures of dental implants and challenges of implant materials. Next, implant materials are examined in three categories, that is, metals, ceramics, and polymers, their mechanical properties, biocompatibility, and bioactivity are summarized. And as an important aspect, strategies of surface modification are also reviewed, along with some finite element analysis to guiding the research direction of implant materials. Finally, the conclusive remarks are outlined to provide an outlook on the future research directions and prospects of dental implants.

Application of Antibiotics/Antimicrobial Agents on Dental Caries

Dental caries is the most common oral disease. The bacteriological aetiology of dental caries promotes the use of antibiotics or antimicrobial agents to prevent this type of oral infectious disease. Antibiotics have been developed for more than 80 years since Fleming discovered penicillin in 1928, and systemic antibiotics have been used to treat dental caries for a long time. However, new types of antimicrobial agents have been developed to fight against dental caries. The purpose of this review is to focus on the application of systemic antibiotics and other antimicrobial agents with respect to their clinical use to date, including the history of their development, and their side effects, uses, structure types, and molecular mechanisms to promote a better understanding of the importance of microbial interactions in dental plaque and combinational treatments.

Emerging Applications of Drug Delivery Systems in Oral Infectious Diseases Prevention and Treatment

The oral cavity is a unique complex ecosystem colonized with huge numbers of microorganism species. Oral cavities are closely associated with oral health and sequentially with systemic health. Many factors might cause the shift of composition of oral microbiota, thus leading to the dysbiosis of oral micro-environment and oral infectious diseases. Local therapies and dental hygiene procedures are the main kinds of treatment. Currently, oral drug delivery systems (DDS) have drawn great attention, and are considered as important adjuvant therapy for oral infectious diseases. DDS are devices that could transport and release the therapeutic drugs or bioactive agents to a certain site and a certain rate in vivo. They could significantly increase the therapeutic effect and reduce the side effect compared with traditional medicine. In the review, emerging recent applications of DDS in the treatment for oral infectious diseases have been summarized, including dental caries, periodontitis, peri-implantitis and oral candidiasis. Furthermore, oral stimuli-responsive DDS, also known as "smart" DDS, have been reported recently, which could react to oral environment and provide more accurate drug delivery or release. In this article, oral smart DDS have also been reviewed. The limits have been discussed, and the research potential demonstrates good prospects.

Achievements in the Topographic Design of Commercial Titanium Dental Implants: Towards Anti-Peri-Implantitis Surfaces

Titanium and its alloys constitute the gold standard materials for oral implantology in which their performance is mainly conditioned by their osseointegration capacity in the host's bone. We aim to provide an overview of the advances in surface modification of commercial dental implants analyzing and comparing the osseointegration capacity and the clinical outcome exhibited by different surfaces. Besides, the development of peri-implantitis constitutes one of the most common causes of implant loss due to bacteria colonization. Thus, a synergic response from industry and materials scientists is needed to provide reliable technical and commercial solutions to this issue. The second part of the review focuses on an update of the recent findings toward the development of new materials with osteogenic and antibacterial capacity that are most likely to be marketed, and their correlation with implant geometry, biomechanical behavior, biomaterials features, and clinical outcomes.

Doxycycline release and antibacterial activity from PMMA/PEO electrospun fiber mats

Objective:

To investigate the use of polymethyl methacrylate (PMMA) electrospun fiber mats containing different amounts of polyethylene oxide (PEO) as a doxycycline delivery system and to test antibacterial activity against an oral pathogen.

Methodology:

PMMA powders or PEO (mol wt 200 Kd) (10,20,30% w/w/) were dissolved in N, N-dimethylformamide (DMF) to obtain a final polymer concentration of 15% in DMF (w/v). 2% Doxycycline monohydrate was added to the solutions and submitted to vortex mixing. The solution was transferred to a plastic syringe and fit into a nanofiber electrospinning unit. The parameters applied were: voltage at 17.2 kV; distance of 20 cm between the needle tip and the collector plate; target speed at 2 m/min; and transverse speed at 1cm/min. Syringe pump speed was 0.15 mm/min. The drug release analysis was performed by removing aliquots of the drug-containing solution (in PBS) at specific periods. Doxycycline release was quantified using RP-HPLC. Fiber mats from all groups had their antibacterial action tested against S. mutans based on inhibition halos formed around the specimens. The experiments were performed in triplicate. Gravimetric analysis at specific periods was performed to determine any polymer loss. Morphological characterization of the electrospun fibers was completed under an optical microscope followed by SEM analysis.

Results:

The addition of PEO to the PMMA fibers did not affect the appearance and diameter of fibers. However, increasing the %PEO caused higher doxycycline release in the first 24 h. Fibers containing 30% PEO showed statistically significant higher release when compared with the other groups. Doxycycline released from the fibers containing 20% or 30% of PEO showed effective against S. mutans.

Conclusion:

The incorporation of PEO at 20% and 30% into PMMA fiber mat resulted in effective drug release systems, with detected antibacterial activity against S. mutans.

Novel bioactive tetracycline-containing electrospun polymer fibers as a potential antibacterial dental implant coating

The purpose of this investigation was to determine the ability of tetracycline-containing fibers to inhibit biofilm formation of peri-implantitis-associated pathogens [i.e., Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn), Prevotella intermedia (Pi), and Aggregatibacter actinomycetemcomitans (Aa)]. Tetracycline hydrochloride (TCH) was added to a poly(DL-lactide) [PLA], poly(ε-caprolactone) [PCL], and gelatin [GEL] polymer blend solution at distinct concentrations to obtain the following fibers: PLA:PCL/GEL (TCH-free, control), PLA:PCL/GEL + 5 % TCH, PLA:PCL/GEL + 10 % TCH, and PLA:PCL/GEL + 25 % TCH. The inhibitory effect of TCH-containing fibers on biofilm formation was assessed by colony-forming units (CFU/mL). Qualitative analysis of biofilm inhibition was done via scanning electron microscopy (SEM). Statistical significance was reported at p < 0.05. Complete inhibition of biofilm formation on the fibers was observed in groups containing TCH at 10 and 25 wt%. Fibers containing TCH at 5 wt% demonstrated complete inhibition of Aa biofilm. Even though a marked reduction in CFU/mL was observed with an increase in TCH concentration, Pi proved to be the most resilient microorganism. SEM images revealed the absence of or a notable decrease in bacterial biofilm on the TCH-containing nanofibers. Collectively, our data suggest that tetracycline-containing fibers hold great potential as an antibacterial dental implant coating.