Local delivery of minocycline-loaded PEG-PLA nanoparticles for the enhanced treatment of periodontitis in dogs

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.

An Overview of Polymeric Nanoplatforms to Deliver Veterinary Antimicrobials

There is an urgent need to find new solutions for the global dilemma of increasing antibiotic resistance in humans and animals. Modifying the performance of existing antibiotics using the nanocarrier drug delivery system (DDS) is a good option considering economic costs, labor costs, and time investment compared to the development of new antibiotics. Numerous studies on nanomedicine carriers that can be used for humans are available in the literature, but relatively few studies have been reported specifically for veterinary pharmaceutical products. Polymer-based nano-DDS are becoming a research hotspot in the pharmaceutical industry owing to their advantages, such as stability and modifiability. This review presents current research progress on polymer-based nanodelivery systems for veterinary antimicrobial drugs, focusing on the role of polymeric materials in enhancing drug performance. The use of polymer-based nanoformulations improves treatment compliance in livestock and companion animals, thereby reducing the workload of managers. Although promising advances have been made, many obstacles remain to be addressed before nanoformulations can be used in a clinical setting. Some crucial issues currently facing this field, including toxicity, quality control, and mass production, are discussed in this review. With the continuous optimization of nanotechnology, polymer-based DDS has shown its potential in reducing antibiotic resistance to veterinary medicines.

Antibacterial-Anti-Inflammatory-Bone Restoration Procedure Achieved by MIN-Loaded PLGA Microsphere for Efficient Treatment of Periodontitis

The main development process of periodontitis involves periodontal pathogenic bacteria as the initiating factor causing the onset of destructive inflammation, which in turn stimulates the destruction of periodontal tissue. It is difficult to achieve the eradication of periodontitis due to the complex interaction among antibacterial, anti-inflammatory, and bone restoration. Herein, we propose an antibacterial-anti-inflammatory-bone restoration procedural treatment strategy with minocycline (MIN) for the efficient treatment of periodontitis. In brief, MIN was prepared into PLGA microspheres with tunable release behavior using different species of PLGA, respectively. The optimally selected PLGA microspheres (LA:GA with 50:50, 10 kDa, and carboxyl group) had a drug loading of 16.91%, an in vitro release of approximately 30 days, which also had a particle size of approximately 11.8 µm with a smooth appearance and a rounded morphology. The DSC and XRD results showed that the MIN was completely encapsulated in the microspheres as an amorphous state. Cytotoxicity tests demonstrated the safety and biocompatibility of the microspheres (cell viabilities at a concentration of 1-200 μg/mL were greater than 97%), and in vitro bacterial inhibition tests showed that the selected microspheres could achieve effective bacterial inhibition at the initial stage after administration. The favorable anti-inflammatory (low TNF-α and IL-10 levels) and bone restoration effects (BV/TV: 71.8869%; BMD: 0.9782 g/cm³; TB.Th: 0.1366 mm; Tb.N: 6.9318 mm^-1; Tb.Sp: 0.0735 mm) were achieved in a SD rat periodontitis model after administering once a week for four weeks. The MIN-loaded PLGA microspheres were proved to be an efficient and safe treatment for periodontitis by procedural antibacterial, anti-inflammatory, and bone restoration.

Biomaterials Used for Periodontal Disease Treatment: Focusing on Immunomodulatory Properties

The growing use of biomaterials with different therapeutic purposes increases the need for their physiological understanding as well as to seek its integration with the human body. Chronic inflammatory local pathologies, generally associated with infectious or autoimmunity processes, have been a current therapeutic target due to the difficulty in their treatment. The recent development of biomaterials with immunomodulatory capacity would then become one of the possible strategies for their management in local pathologies, by intervening in situ, without generating alterations in the systemic immune response. The treatment of periodontal disease as an inflammatory entity has involved the use of different approaches and biomaterials. There is no conclusive, high evidence about the use of these biomaterials in the regeneration of periodontitis sequelae, so the profession keeps looking for other different strategies. The use of biomaterials with immunomodulatory properties could be one, with a promising future. This review of the literature summarizes the scientific evidence about biomaterials used in the treatment of periodontal disease.

Evaluation of the effect of coenzyme Q10 supplementation along with scaling and root planing (SRP) on periodontal and gingival indices in controlled diabetic patients

Background. This clinical trial evaluated the effect of coenzyme Q10 supplementation along with scaling and root planing (SRP) on periodontal and gingival indices in controlled diabetic patients. Methods. Forty-two diabetic patients (controlled type), referred to the Department of Periodontics with chronic periodontitis and eligible for the study, were included in the study. Patients suffering from chronic periodontitis with a probing pocket depth of ≥5 mm in different quadrants of the oral cavity with radiographic evidence of bone loss were included in the present randomized, double-masked, placebo-controlled clinical trial. The subjects were instructed to take one capsule of coenzyme Q10 or a placebo every day for 30 days following SRP. Clinical parameters, i.e., plaque index (PI), gingival index (GI), bleeding on probing (BOP), clinical attachment level (CAL), and probing pocket depth (PPD), were recorded at baseline and four weeks after treatment by two masked and calibrated examiners. The study results were reported as (mean ± standard deviations) and frequencies (percentages). Results. One month after the intervention, PPD, CAL, BOP, and PI indices in the intervention group were significantly lower than those in the control group. One month after the intervention, the GI was similar in both groups. A significant decrease was observed in the GI in both groups after the intervention. Conclusion. The results of the present study showed that Q10 orally with scaling and root planing in patients with controlled diabetes with chronic periodontitis might accelerate the treatment process and significantly reduce the pocket depth.

Future Drug Targets in Periodontal Personalised Medicine-A Narrative Review

Periodontal disease is an infection-driven inflammatory disease characterized by the destruction of tooth-supporting tissues. The establishment of chronic inflammation will result in progressive destruction of bone and soft tissue changes. Severe periodontitis can lead to tooth loss. The disease has complex pathogenesis with an interplay between genetic, environmental, and host factors and pathogens. Effective management consists of plaque control and non-surgical interventions, along with adjuvant strategies to control inflammation and disrupt the pathogenic subgingival biofilms. Recent studies have examined novel approaches for managing periodontal diseases such as modulating microbial signaling mechanisms, tissue engineering, and molecular targeting of host inflammatory substances. Mounting evidence suggests the need to integrate omics-based approaches with traditional therapy to address the disease. This article discusses the various evolving and future drug targets, including proteomics, gene therapeutics, vaccines, and nanotechnology in personalized periodontal medicine for the effective management of periodontal diseases.

Nano Drug Delivery Platforms for Dental Application: Infection Control and TMJ Management-A Review

The oral cavity is an intricate environment subjected to various chemical, physical, and thermal injuries. The effectiveness of the local and systemically administered drugs is limited mainly due to their toxicities and poor oral bioavailability that leads to the limited effectiveness of the drugs in the target tissues. To address these issues, nanoparticle drug delivery systems based on metals, liposomes, polymeric particles, and core shells have been developed in recent years. Nano drug delivery systems have applications in the treatment of patients suffering from temporomandibular joint disorders such as preventing degeneration of cartilage in patients suffering from rheumatoid arthritis and osteoarthritis and alleviating the pain along with it. The antibacterial dental applications of nano-drug delivery systems such as silver and copper-based nanoparticles include these agents used to arrest dental caries, multiple steps in root canal treatment, and patients suffering from periodontitis. Nanoparticles have been used in adjunct with antifungals to treat oral fungal infections such as candida albicans in denture wearers. Acyclovir being the most commonly used antiviral has been used in combination with nanoparticles against an array of viral infections such as the herpes simplex virus. Nanoparticles based combination agents offer more favorable drug release in a controlled manner along with efficient delivery at the site of action. This review presents an updated overview of the recently developed nanoparticles delivery systems for the management of temporomandibular joint disorders along with the treatment of different oral infections.

Engineering Polymeric Nanosystems against Oral Diseases

Nanotechnology and nanoparticles (NPs) are at the forefront of modern research, particularly in the case of healthcare therapeutic applications. Polymeric NPs, specifically, hold high promise for these purposes, including towards oral diseases. Careful optimisation of the production of polymeric NPs, however, is required to generate a product which can be easily translated from a laboratory environment to the actual clinical usage. Indeed, considerations such as biocompatibility, biodistribution, and biodegradability are paramount. Moreover, a pre-clinical assessment in adequate in vitro, ex vivo or in vivo model is also required. Last but not least, considerations for the scale-up are also important, together with an appropriate clinical testing pathway. This review aims to eviscerate the above topics, sourcing at examples from the recent literature to put in context the current most burdening oral diseases and the most promising polymeric NPs which would be suitable against them.

Electrosprayed minocycline hydrochloride-loaded microsphere/SAIB hybrid depot for periodontitis treatment

Minocycline hydrochloride (MINO) has been one of the most frequently used antibiotics in the treatment of periodontitis due to its antibacterial activity and osteogenesis effects; however, high levels of MINO administered during the treatment halt the formation of new bone. Therefore, the purpose of the present study was to prepare a MINO-microsphere/sucrose acetate isobutyrate (SAIB) hybrid depot to reduce the burst release of MINO and ensure antibacterial and osteogenesis effects of MINO in the treatment of periodontitis. Uniform microspheres, approximately 5 µm size, with a slightly rough surface and different MINO loading (10, 12, and 14%) were prepared, and the microspheres were added into SAIB, after which the burst release significantly decreased from 66.18 to 2.92%, from 71.82 to 3.82%, and from 73.35 to 4.45%, respectively, and the release from all the MINO-microspheres/SAIB hybrid depots lasted for 77 days. In addition, cytotoxicity test showed that the MINO-microsphere with 12% drug loading promoted the proliferation of osteoblasts the most and was subsequently used in vivo experiments. Moreover, in the model of ligatured-induced periodontitis in SD rats, the MINO-microsphere/SAIB hybrid depot not only significantly increased the alveolar bone height and bone volume but also reduced the inflammation of the periodontal tissue. Additionally, it also inhibited the expression of the receptor activator of nuclear factor-kappa B ligand (RANKL) and promoted the expression of osteoprotegerin (OPG).. These results indicated that the MINO-microsphere/SAIB hybrid depot might be promising in the treatment of periodontitis.

Efficacy of Local Minocycline Agents in Treating Peri-Implantitis: An Experimental In Vivo Study in Beagle Dogs

BACKGROUND

Local delivery agents (LDA) have the advantage of delivering the antibiotics at high concentrations to the targeted sites. However, the constant flow of gingival crevicular fluids and saliva may restrict their efficacy. Therefore, the drug sustainability and pharmacodynamic properties of any proposed LDA should be evaluated.

METHODS

Four dental implants were placed unilaterally in the edentulous mandible of six beagle dogs. Peri-implantitis were experimentally induced using silk-ligatures. Each implant was randomly allocated to receive one of the following four treatments: (i) MC (Chitosan-alginate (CA) minocycline), (ii) MP (CA-without minocycline), (iii) PG (Polyacrylate-glycerin minocycline), and (iv) Control (mechanical debridement only). Mechanical therapies and LDAs were administered into the gingival sulcus two times at a 4-week interval. Drug sustainability as well as clinical, radiographical, and immunohistochemical (IHC) analyses were conducted to evaluate the efficacies of treatments.

RESULTS

Reduced mean probing depth was observed in all of the test groups after the second delivery. A minimal marginal bone level change was observed during the treatment period (MP (-0.06 ± 0.53 mm) to PG (-0.25 ± 0.42 mm)). The distribution of IHC cell marker analysis of all targeted antibodies ranged from 6.34% to 11.33%. All treatment outcomes between the test groups were comparable. A prolonged retention of LDA was observed from CA microspheres (MC and MP) at both administrations (p < 0.017) and prolonged sustainability of bacteriostatic effect was observed from MC compared to PG after the second administration (p < 0.05).

CONCLUSIONS

Prolonged retention of CA microspheres was observed and the longer bacteriostatic effect was observed from the MC group. Mechanical debridement with adjunct LDA therapy may impede peri-implantitis progression, however, prolonged drug action did not lead to improved treatment outcome.

Locally Applied Slow-Release of Minocycline Microspheres in the Treatment of Peri-Implant Mucositis: An Experimental In Vivo Study

BACKGROUND

The objective of this is preclinical investigation was to evaluate the differential drug sustainability and pharmacodynamic properties of two local minocycline microsphere carriers: chitosan-coated alginate (CA) and poly(meth)acrylate-glycerin (PG).

METHODS

Four dental implants were placed unilaterally in the edentulous mandible of six beagle dogs. Each implant was randomly assigned to receive one of the following four treatments: (i) CA (CA-based minocycline), (ii) placebo (CA substrate without minocycline), (iii) PG (PG-based minocycline) and (iv) control (mechanical debridement only). After inducing peri-implant mucositis, the randomly assigned treatments were administered into the gingival sulcus twice at a 4-week interval using a plastic-tipped syringe. Drug sustainability and pharmacodynamic (clinical, radiographical and cell marker intensity) evaluations were performed after each administration.

RESULTS

The CA microspheres remained longer around the healing abutment compared to the PG microspheres at both administrations and a longer bacteriostatic effect was observed from CA (7.0 ± 5.7 days) compared to PG (1.2 ± 2.6 days). The efficacy of the applied therapies based on clinical, radiographical and histological analyses were comparable across all treatment groups.

CONCLUSIONS

CA microspheres showed longer carrier and bacteriostatic effect sustainability when compared to PG microspheres, however, longer drug sustainability did not lead to improved treatment outcomes.

Rapid Release Polymeric Fibers for Inhibition of Porphyromonas gingivalis Adherence to Streptococcus gordonii

Active agents targeting key bacterial interactions that initiate biofilm formation in the oral cavity, may alter periodontitis progression; however, to date, specifically-targeted prophylactic and treatment strategies have been limited. Previously we developed a peptide, BAR (SspB Adherence Region), that inhibits oral P. gingivalis/S. gordonii biofilm formation in vitro and in vivo, and BAR nanoparticles that increase BAR effectiveness via multivalency and prolonged delivery. However, limited BAR loading and nanoparticle retention in the oral cavity can result in inadequate release and efficaciousness. Given this, an effective delivery platform that can release concentrations of BAR suitable for twice-daily applications, may offer an alternative that enhances loading, ease of administration, and retention in the oral cavity. With this in mind, the study objectives were to develop and characterize a rapid-release platform, composed of polymeric electrospun fibers (EFs) that encapsulate BAR, and to evaluate fiber safety and functionality against P. gingivalis/S. gordonii biofilms in vitro. Poly(lactic-co-glycolic acid) (PLGA), poly(L-lactic acid) (PLLA), and polycaprolactone (PCL) were electrospun alone or blended with polyethylene oxide (PEO), to provide high BAR loading and rapid-release. The most promising formulation, 10:90 PLGA:PEO EFs, provided 95% BAR release after 4 h, dose-dependent inhibition of biofilm formation (IC50 = 1.3 μM), disruption of established dual-species biofilms (IC50 = 2 μM), and maintained high cell viability. These results suggest that BAR-incorporated EFs may provide a safe and specifically-targeted rapid-release platform to inhibit and disrupt dual-species biofilms, that we envision may be applied twice-daily to exert prophylactic effect in the oral cavity.

Nobiletin-loaded micelles reduce ovariectomy-induced bone loss by suppressing osteoclastogenesis

Background

Nobiletin (NOB), a polymethoxy flavonoid, possesses anti-cancer and anti-inflammatory activities, has been reported that it played role in anti-osteoporosis treatment. However, previous research did not focus on practical use due to lack of hydrophilicity and cytotoxicity at high concentrations. The aim of this study was to develop a therapeutic formulation for osteoporosis based on the utilization of NOB.

Methods

In this study, NOB-loaded poly(ethylene glycol)-block-poly(e-caprolactone) (NOB-PEG-PCL) was prepared by dialysis method. The effects on osteoclasts and anti-osteoporosis functions were investigated in a RANKL-induced cell model and ovariectomized (OVX) mice.

Results

Dynamic light scattering and transmission electron microscopy examination results revealed that the NOB-PEG-PCL had a round shape, with a mean diameter around 124 nm. The encapsulation efficiency and drug loading were 76.34±3.25% and 7.60±0.48%, respectively. The in vitro release of NOB from NOB-PEG-PCL showed a remarkably sustained releasing characteristic and could be retained at least 48 hrs in pH 7.4 PBS. Anti-osteoclasts effects demonstrated that the NOB-PEG-PCL significantly inhibited the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells stimulated by RANKL. Furthermore, the NOB-PEG-PCL did not produce cytotoxicity on bone marrow-derived macrophages (BMMs). The mRNA expressions of genetic markers of osteoclasts including TRAP and cathepsin K were significantly decreased in the presence of NOB-PEG-PCL. In addition, the NOB-PEG-PCL inhibited OC differentiation of BMMs through RANKL-induced MAPK signal pathway. After administration of the NOB-PEG-PCL, NOB-PEG-PCL prevented bone loss and improved bone density in OVX mice. These findings suggest that NOB-PEG-PCL might have great potential in the treatment of osteoporosis.

Conclusion

The results suggested that NOB-PEG-PCL micelles could effectively prevent NOB fast release from micelles and extend circulation time. The NOB-PEG-PCL delivery system may be a promising way to prevent and treat osteoporosis.

Dual micelles-loaded gelatin nanofibers and their application in lipopolysaccharide-induced periodontal disease

INTRODUCTION

Combined therapies utilizing inhibitors to remove pathogens are needed to suppress lipopolysaccharide (LPS)-induced periodontal disease. We prepared a novel, multi-agent delivery scaffold for periodontal treatment.

METHODS

In this study, we synthesized SP600125 (a JNK inhibitor) and SB203580 (a p38 inhibitor) drug-loaded poly(ethylene glycol)-block-caprolactone copolymer via dialysis method. The physical property of micelles was characterized through dynamic light scattering and transmission electron microscopy. The cell growth and LPS-induced MMP-2 and MMP-13 expression were evaluated through CCK-8, real-time PCR and Western blot assay. The release of SP600125 and SB203580 from different scaffolds was estimated. Microcomputed tomography and histology were used for evaluating the effect of the micelles-loaded nanofibers on the treatment of class II furcation defects in dogs.

RESULTS

The drug was then successfully incorporated into gelatin fibers during electrospinning process. We confirmed that the micelles had spherical structure and an average particle size of 160 nm for SP600125-micelles (SP-Ms) and 150 nm for SB203580-micelles (SB-Ms). The nanofiber scaffold showed excellent encapsulation capability, in vitro drug-release behavior, and cell compatibility. Real-time PCR and Western blot assay further indicated that LPS-induced MMP-2 and MMP-13 expression was significantly inhibited by the scaffold.

CONCLUSION

The results suggested that the dual drug-loaded system developed in this study might become a highly effective therapy for periodontal disease.

Functional assessment of peptide-modified PLGA nanoparticles against oral biofilms in a murine model of periodontitis

The interaction of the periodontal pathogen Porphyromonas gingivalis (Pg) with commensal streptococci promotes Pg colonization of the oral cavity. Previously, we demonstrated that a peptide (BAR) derived from Streptococcus gordonii (Sg) potently inhibited adherence of Pg to streptococci and reduced Pg virulence in a mouse model of periodontitis. Thus, BAR may represent a novel therapeutic to control periodontitis by preventing Pg colonization of the oral cavity. However, while BAR inhibited the initial formation of Pg/Sg biofilms, much higher concentrations of peptide were required to disrupt an established Pg/Sg biofilm. To improve the activity of the peptide, poly(lactic-co-glycolic acid) (PLGA) nanoparticles were surface-modified with BAR and shown to more potently disrupt Pg/Sg biofilms relative to an equimolar amount of free peptide. The goal of this work was to determine the in vivo efficacy of BAR-modified NPs (BNPs) and to assess the toxicity of BNPs against human gingival epithelial cells. In vivo efficacy of BNPs was assessed using a murine model of periodontitis by measuring alveolar bone resorption and gingival IL-17 expression as outcomes of Pg-induced inflammation. Infection of mice with Pg and Sg resulted in a significant increase in alveolar bone loss and gingival IL-17 expression over sham-infected animals. Treatment of Pg/Sg infected mice with BNPs reduced bone loss and IL-17 expression almost to the levels of sham-infected mice and to a greater extent than treatment with an equimolar amount of free BAR. The cytotoxicity of the maximum concentration of BNPs and free BAR used in in vitro and in vivo studies (1.3 and 3.4 μM), was evaluated in telomerase immortalized gingival keratinocytes (TIGKs) by measuring cell viability, cell lysis and apoptosis. BNPs were also tested for hemolytic activity against sheep erythrocytes. TIGKs treated with BNPs or free BAR demonstrated >90% viability and no significant lysis or apoptosis relative to untreated cells. In addition, neither BNPs nor free BAR exhibited hemolytic activity. In summary, BNPs were non-toxic within the evaluated concentration range of 1.3-3.4 μM and provided more efficacious protection against Pg-induced inflammation in vivo, highlighting the potential of BNPs as a biocompatible platform for translatable oral biofilm applications.

Novel Bioactive and Therapeutic Dental Polymeric Materials to Inhibit Periodontal Pathogens and Biofilms

Periodontitis is a common infectious disease characterized by loss of tooth-supporting structures, which eventually leads to tooth loss. The heavy burden of periodontal disease and its negative consequence on the patient's quality of life indicate a strong need for developing effective therapies. According to the World Health Organization, 10⁻15% of the global population suffers from severe periodontitis. Advances in understanding the etiology, epidemiology and microbiology of periodontal pocket flora have called for antibacterial therapeutic strategies for periodontitis treatment. Currently, antimicrobial strategies combining with polymer science have attracted tremendous interest in the last decade. This review focuses on the state of the art of antibacterial polymer application against periodontal pathogens and biofilms. The first part focuses on the different polymeric materials serving as antibacterial agents, drug carriers and periodontal barrier membranes to inhibit periodontal pathogens. The second part reviews cutting-edge research on the synthesis and evaluation of a new generation of bioactive dental polymers for Class-V restorations with therapeutic effects. They possess antibacterial, acid-reduction, protein-repellent, and remineralization capabilities. In addition, the antibacterial photodynamic therapy with polymeric materials against periodontal pathogens and biofilms is also briefly described in the third part. These novel bioactive and therapeutic polymeric materials and treatment methods have great potential to inhibit periodontitis and protect tooth structures.

BAR-encapsulated nanoparticles for the inhibition and disruption of Porphyromonas gingivalis-Streptococcus gordonii biofilms

Background

Porphyromonas gingivalis adherence to oral streptococci is a key point in the pathogenesis of periodontal diseases (Honda in Cell Host Microbe 10:423–425, 2011). Previous work in our groups has shown that a region of the streptococcal antigen denoted BAR (SspB Adherence Region) inhibits P. gingivalis/S. gordonii interaction and biofilm formation both in vitro and in a mouse model of periodontitis (Daep et al. in Infect Immun 74:5756–5762, 2006; Daep et al. in Infect immun 76:3273–3280, 2008; Daep et al. in Infect Immun 79:67–74, 2011). However, high localized concentration and prolonged exposure are needed for BAR to be an effective therapeutic in the oral cavity.

Methods

To address these challenges, we fabricated poly(lactic-co-glycolic acid) (PLGA) and methoxy-polyethylene glycol PLGA (mPEG-PLGA) nanoparticles (NPs) that encapsulate BAR peptide, and assessed the potency of BAR-encapsulated NPs to inhibit and disrupt in vitro two-species biofilms. In addition, the kinetics of BAR-encapsulated NPs were compared after different durations of exposure in a two-species biofilm model, against previously evaluated BAR-modified NPs and free BAR.

Results

BAR-encapsulated PLGA and mPEG-PLGA NPs potently inhibited biofilm formation (IC50 = 0.7 μM) and also disrupted established biofilms (IC50 = 1.3 μM) in a dose-dependent manner. In addition, BAR released during the first 2 h of administration potently inhibits biofilm formation, while a longer duration of 3 h is required to disrupt pre-existing biofilms.

Conclusions

These results suggest that BAR-encapsulated NPs provide a potent platform to inhibit (prevent) and disrupt (treat) P. gingivalis/S. gordonii biofilms, relative to free BAR.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0396-4) contains supplementary material, which is available to authorized users.

Development and Evaluation of Minocycline Hydrochloride-Loaded In Situ Cubic Liquid Crystal for Intra-Periodontal Pocket Administration

In the present study, an injectable in situ liquid crystal formulation was developed for local delivery of minocycline hydrochloride (MH) for chronic periodontitis treatment. The physicochemical properties, phase structures, in vitro drug release and pharmacodynamics of in situ liquid crystals were investigated. The optimal formulation (phytantriol (PT)/propylene glycol (PG)/water, 63/27/10, w/w/w) loaded with 20 mg/g MH was proved to be injectable. The precursor formulation can form a cubic phase gel in excess water in 6.97 ± 0.10 s. The results of in vitro drug release suggested the MH presented a sustained release for 4 days. Liquid crystal precursor formulation significantly reduced gingival index, probing depth and alveolar bone loss compared to the model group (p < 0.01). Besides, the pathological characteristics of model rats were improved. The results suggested that MH-loaded in situ cubic liquid crystal possessed of sustained release ability and periodontal clinical symptoms improvement. The developed in situ cubic liquid crystal may be a potentially carrier in the local delivery of MH for periodontal diseases.

[Efficacy of minocycline hydrochloride combined with flap surgery for chronic periodontitis: a Meta-analysis]

OBJECTIVE

This study aimed to evaluate the efficacy of 2% minocycline hydrochloride combined with flap surgery in the treatment of chronic periodontitis. The superiority of this therapy to simple flap surgery was also explored.

METHODS

We searched the databases of CNKI, VIP, Wanfang, Chinese Biomedical Literature, PubMed, ScienceDirect, and Embase from inception to July 2017. Two reviewers independently screened literature, extracted data, and evaluated the bias risk of included studies. Then, Meta-analysis was performed using RevMan 5.3 software.

RESULTS

A total of seven randomized controlled trials involving 217 patients were included. Meta-analysis showed that, in two groups, the changes in probing depth (PD) [MD=-0.55, 95%CI (-0.84, -0.26), P=0.000 2] and plaque index [MD=-0.08, 95%CI (-0.15, -0.01), P=0.03] at 3 and 6 months of PD [MD=-0.62, 95%CI (-1.04, -0.21), P=0.003] had statistically significant difference (P<0.05). The clinical attachment loss (CAL) [MD=-0.21, 95%CI (-0.47, 0.04), P=0.10] had no statistically significant difference after 3 months (P>0.05), but the improvement in CAL was significantly improved by minocycline hydrochloride combined with flap therapy.

CONCLUSIONS

Periodontal flap combined with minocycline adjuvant therapy for chronic periodontitis is effective in short-term observations.

Current perspectives regarding the application and incorporation of silver nanoparticles into dental biomaterials

INTRODUCTION

The key idea of nanotechnology is to construct and preserve functional structures by means of exploiting atoms and molecules. Nanotechnology has proven to be crucial in pharmacological medicine, tissue engineering, clinical diagnosis, long term conservation of biological tissues in a cryogenic state, protein detection, tumor destruction and magnetic resonance imaging.The aim of this paper is to review the literature on the specific characteristics of nanostructured materials, their applications and advantages that they bring to dentistry.

METHOD

We conducted an electronic scientific database research that included PubMed, Cochrane and Medline. The following keywords were used: nanotechnology, nanodentistry and silver nanoparticles. Initially 1650 original articles were retrieved from the these mentioned international databases, which were screened in detail. We included literature reviews that dealt with the comprehensive applications of nanostructured particles and silver nanoparticles in particular, in all fields of contemporary dentistry. Case reports, clinical trials, editorials and opinion letters were excluded in the first phase of our research. Fifty two articles met all the selection criteria and were ultimately selected and reviewed.

RESULTS

Nanotechnology deals with the production of various types of nanomaterials with potential applications in the field of biomedicine. Silver nanoparticles have the capacity to eliminate dental caries producing bacteria or repair teeth enamel with signs of dental decay. Nanodentistry will allow better oral health by use of nanostructured materials. Treatment opportunities that nanotechnology has to offer in contemporary dentistry include local anesthesia, permanent treatment of dental hypersensitivity, orthodontic and oral health care with nanorobotic dentifrice.

CONCLUSION

The studies that we reviewed are largely in favor of nanotechnology and nanostructured materials, highlighting their qualities and enhancements they bring to the field of dentistry. Although many of these products that benefit from silver nanoparticles properties are still expensive and exclusive, we can foresee major improvements and demand regarding dental biomaterials with nanoparticles incorporated in the near future.

Activated Microglia Targeting Dendrimer-Minocycline Conjugate as Therapeutics for Neuroinflammation

Brain-related disorders have outmatched cancer and cardiovascular diseases worldwide as the leading cause of morbidity and mortality. The lack of effective therapies and the relatively dry central nervous system (CNS) drug pipeline pose formidable challenge. Superior, targeted delivery of current clinically approved drugs may offer significant potential. Minocycline has shown promise for the treatment of neurological diseases owing to its ability to penetrate the blood-brain barrier (BBB) and potency. Despite its potential in the clinic and in preclinical models, the high doses needed to affect a positive therapeutic response have led to side effects. Targeted delivery of minocycline to the injured site and injured cells in the brain can be highly beneficial. Systemically administered hydroxyl poly(amidoamine) (PAMAM) generation-6 (G6) dendrimers have a longer blood circulation time and have been shown to cross the impaired BBB. We have successfully prepared and characterized the in vitro efficacy and in vivo targeting ability of hydroxyl-G6 PAMAM dendrimer-9-amino-minocycline conjugate (D-mino). Minocycline is a challenging drug to carry out chemical transformations due to its inherent instability. We used a combination of a highly efficient and mild copper catalyzed azide-alkyne click reaction (CuAAC) along with microwave energy to conjugate 9-amino-minocycline (mino) to the dendrimer surface via enzyme responsive linkages. D-mino was further evaluated for anti-inflammatory and antioxidant activity in lipopolysaccharides-activated murine microglial cells. D-mino conjugates enhanced the intracellular availability of the drug due to their rapid uptake, suppressed inflammatory cytokine tumor necrosis factor α (TNF-α) production, and reduced oxidative stress by suppressing nitric oxide production, all significantly better than the free drug. Fluorescently labeled dendrimer conjugate (Cy5-D-mino) was systematically administered (intravenous, 55 mg/kg) on postnatal day 1 to rabbit kits with a clinically relevant phenotype of cerebral palsy. The in vivo imaging study indicates that Cy5-D-mino crossed the impaired blood-brain barrier and co-localized with activated microglia at the periventricular white matter areas, including the corpus callosum and the angle of the lateral ventricle, with significant implications for positive therapeutic outcomes. The enhanced efficacy of D-mino, when combined with the inherent neuroinflammation-targeting capability of the PAMAM dendrimers, may provide new opportunities for targeted drug delivery to treat neurological disorders.

Plasma concentration of metformin and dexamethasone after administration through Osseogate

BACKGROUND

Osseogate is a novel drug delivery route through bone marrow involving a modified implant used as the drug delivery system. The purpose of this study was to evaluate the effects of individual drug physicochemical characteristics on the pharmacokinetic behavior when using the Osseogate as administration route.

METHODS

Implant-mediated drug delivery systems (IMDDS) were installed in a total of 18 rabbits. After complete healing, water-soluble metformin hydrochloride was administered to one group (n = 9) while poorly soluble dexamethasone was administered to the other group (n = 9). The release patterns of each group were monitored for two weeks by measuring the plasma concentration of each drug.

RESULTS

Both groups showed relative sustained release. However, metformin hydrochloride showed more rapid diffusion and early termination of drug release compared with dexamethasone.

CONCLUSIONS

The physicochemical properties of drugs significantly affected the release pattern through Osseogate. Further research is required to achieve controlled delivery using this route.

[Research progress on a nanodrug delivery system for prevention and control of dental caries and periodontal diseases]

Dental caries and periodontal diseases are common chronic infectious diseases that cause serious damage to oral health. Bacteria is the primary factor leading to such conditions. As a dental plaque control method, chemotherapeutic agents face serious challenges in dental care because of the specific physiological and anatomical characteristics of the oral cavity. Nanodrug delivery system is a series of new drug delivery systems at nanoscale, and it can target cells, promote sustainedrelease effects, and enhance biodegradation. This review focuses on research progress on nanodrug delivery systems for prevention and control of dental caries and periodontal diseases.

Nanomedicines for dental applications-scope and future perspective

Nanotechnology is directed at manipulating matter at the nanometer level and the application of the same to medicine is called nanomedicine. Over the past few years researchers have developed various nanomedicines for diagnosis, prevention as well as cure of various ailments both locally and systemically. In dentistry, drug loaded nanopharmaceuticals based on nanomaterials have been utilized extensively over the past few years to cure dental problems and facilitate attainment of a near-perfect oral hygiene. Although various drug delivery systems have already been investigated for treating periodontitis, research is currently focused on nanodelivery systems for efficient targeted delivery of drugs to the periodontal pocket. In this context a few nanodelivery systems explored include nanocomposite hydrogels, nanoparticles, nanoemulsion etc. A number of herbal and synthetic drugs examples of which include trichlosan, tetracycline, Harungana madagascariensis leaf extract, minocycline, metronidazole, chlorhexidine have been encapsulated into nanodelivery systems for treating periodontitis. A few examples of polymers investigated as matrices for the delivery of drugs to the periodontal pocket include chitosan, Poly lactic-co-glycolic acid copolymer, poly e caprolactone, polylactic acid, polypropylene, cellulose acetate propionate and ethyl vinyl acetate. In the near future also nanotechnology is expected to find its application in all the specializations of dentistry ranging from diagnosis and treatment of oral cancers to development of colloidal suspension containing millions of active analgesic micron-size dental robots resulting in anesthesia in patients. In the light of the above facts the current editorial focuses on the applications of nanotechnology based nanomedicines which cannot be undermined in the improvement of dental health and hygiene both, in the current as well as in future scenario.