Protective effect of Chromobacterium violaceum and violacein against bone resorption by periodontitis.

OBJECTIVES: The aim of this study was to evaluate the potential protective effect of Chromobacterium violaceum and violacein against periodontitis, in experimental models. MATERIALS AND METHODS: A double-blind experimental study on the exposure to C. violaceum or violacein in experimentally ligature-induced periodontitis, as preventive factors against alveolar bone loss by periodontitis. Bone resorption was assessed by morphometry. Antibacterial potential of violacein was assessed in an in vitro assay. Its cytotoxicity and genotoxicity were evaluated using the Ames test and SOS Chromotest assay, respectively. RESULTS: The potential of C. violaceum to prevent/limit bone resorption by periodontitis was confirmed. Daily exposure to 106 cells/ml in water intake since birth and only during the first 30 days of life significantly reduced bone loss from periodontitis in teeth with ligature. Violacein extracted from C. violaceum was efficient in inhibiting or limiting bone resorption and had a bactericidal effect against Porphyromonas gingivalis in the in vitro assay. CONCLUSIONS: We conclude that C. violaceum and violacein have the potential to prevent or limit the progression of periodontal diseases, in an experimental model. CLINICAL RELEVANCE: The effect of an environmental microorganism with potential action against bone loss in animal models with ligature-induced periodontitis represents the possibility of understanding the etiopathogenesis of periodontal diseases in populations exposed to C. violaceum and the possibility of new probiotics and antimicrobials. This would imply new preventive and therapeutic possibilities.

Comparison of antibacterial effect of plantaricin 149 suspension and traditional root canal irrigation solutions in root canal infections in vitro.

Dental pulp and periapical diseases are common conditions in stomatology, caused by various pathogenic microorganisms. Antimicrobial peptides, as new antibiotics, offer promising applications in the irrigation and disinfection medicaments for root canals.One patient with chronic periapical periodontitis was selected to extract the clinical pathogenic bacteria. Porphyromonas gingivalis (Pg) (ATCC 33,277), Streptococcus mutans (Sm) (ATCC 25,175), and Prevotella intermedius (Pi) (ATCC 25,611) were used as test strains. The effects of plantaricin (Pln) 149 on the biofilm formation and growth in infected root canals were evaluated by RT-PCR, laser confocal scanning microscopy, and bacterial diversity analysis. In addition, the cytotoxicity of Pln 149 (100 µg/mL) to human dental pulp stem cells (hDPSCs) was assessed using an MTT assay. Pln 149 exhibited significant inhibitory effects on Pg Sm and Pi (P < 0.05), with significant differences in the biofilm images of the laser confocal scanning microscope (P < 0.05). There were no significant differences in hDPSCs viability or proliferation between the Pln 149 and control groups. Considering the excellent antimicrobial effects and low cytotoxicity, we suggest that Pln 149 might be a promising option for root canal irrigation solutions.

An ionic silver coating prevents implant-associated infection by anaerobic bacteria in vitro and in vivo in mice.

Currently, implants are utilized clinically for bone transplant procedures. However, if infectious osteomyelitis occurs at implant sites, removal of bacteria can be challenging. Moreover, altered blood flow at peri-implant infectious sites can create an anaerobic environment, making it more difficult to treat infection with antibiotics. Thus, it would be beneficial if implants could be modified to exhibit antibacterial activity, even in anaerobic conditions. Here, we show antibacterial activity of silver ions coated on titanium rods, even against the anaerobic bacteria Porphyromonas gingivalis (P. gingivalis), both in vitro and in vivo. Specifically, we implanted silver-coated or control uncoated titanium rods along with P. gingivalis in mouse femoral bone BM cavities and observed significantly inhibited P. gingivalis infection with silver-coated compared with non-coated rods, based on in vivo bio-imaging. Osteonecrosis by infectious osteomyelitis and elevation of the inflammatory factors C-reactive protein and IL-6 promoted by P. gingivalis s were also significantly reduced in the presence of silver-coated rods. Overall, our study indicates that silver ion coating of an implant represents a therapeutic option to prevent associated infection, even in anaerobic conditions or against anaerobic bacteria.

Screening biofilm eradication activity of ethanol extracts from foodstuffs: potent biofilm eradication activity of glabridin, a major flavonoid from licorice (Glycyrrhiza glabra), alone and in combination with ɛ-poly-L-lysine.

The ethanol extracts of 155 different foodstuffs containing medicinal plants were investigated for their biofilm eradication activities against pathogenic bacteria. A combined method of a colorimetric microbial viability assay based on reduction of a tetrazolium salt (WST-8) and a biofilm formation technique on the 96-pins of a microtiter plate lid was used to screen the biofilm eradication activities of foodstuffs. The ethanol extracts of licorice (Glycyrrhiza glabra) showed potent biofilm eradication activities against Streptococcus mutans, Staphylococcus aureus, and Porphyromonas gingivalis. Among the antimicrobial constituents in licorice, glabridin had the most potent eradication activities against microbial biofilms. The minimum biofilm eradication concentration of glabridin was 25-50 µg/ml. Furthermore, the combination of glabridin with ɛ-poly-L-lysine, a food additive, could result in broad biofilm eradication activities towards a wide variety of bacteria associated with infection, including Escherichia coli and Pseudomonas aeruginosa.

The molecular mechanism, targets, and novel molecules in the treatment of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurological illness that causes dementia mainly in the elderly. The challenging obstacles related to AD has freaked global healthcare system to encourage scientists in developing novel therapeutic startegies to overcome with the fatal disease. The current treatment therapy of AD provides only symptomatic relief and to some extent disease-modifying effects. The current approach for AD treatment involves designing of cholinergic inhibitors, Aß disaggregation inducing agents, tau inhibitors and several antioxidants. Hence, extensive research on AD therapy urgently requires a deep understanding of its pathophysiology and exploration of various chemical scaffolds to design and develop a potential drug candidate for the treatment. Various issues linked between disease and therapy need to be considered such as BBB penetration capability, clinical failure and multifaceted pathophisiology requires a proper attention to develop a lead candidate. This review article covers all probable mechanisms including one of the recent areas for investigation i.e., lipid dyshomeostasis, pathogenic involvement of P. gingivalis and neurovascular dysfunction, recently reported molecules and drugs under clinical investigations and approved by FDA for AD treatment. Our summarized information on AD will attract the researchers to understand and explore current status and structural modifications of the recently reported heterocyclic derivatives in drug development for AD therapy.

Direct current exerts electricidal and bioelectric effects on Porphyromonas gingivalis biofilms partially via promoting oxidative stress and antibiotic transport.

Low electric current can inhibit certain microbial biofilms and enhance the efficacy of antimicrobials against them. This study investigated the electricidal and bioelectric effects of direct current (DC) against Porphyromonas gingivalis biofilms as well as the underlying mechanisms. Here, we firstly showed that DC significantly suppressed biofilm formation of P. gingivalis in time- and intensity-dependent manners, and markedly inhibited preformed P. gingivalis biofilms. Moreover, DC enhanced the killing efficacy of metronidazole (MTZ) and amoxicillin with clavulanate potassium (AMC) against the biofilms. Notably, DC-treated biofilms displayed upregulated intracellular ROS and expression of ROS related genes (sod, feoB, and oxyR) as well as porin gene. Interestingly, DC-induced killing of biofilms was partially reversed by ROS scavenger N-dimethylthiourea (DMTU), and the synergistic effect of DC with MTZ/AMC was weakened by small interfering RNA of porin gene (si-Porin). In conclusion, DC can exert electricidal and bioelectric effects against P. gingivalis biofilms partially via promotion of oxidative stress and antibiotic transport, which offers a promising approach for effective management of periodontitis.

Synergistic antibacterial activity of herbal extracts with antibiotics on bacteria responsible for periodontitis.

INTRODUCTION: Development of bacterial resistance and antimicrobial side-effect has shifted the focus of research toward Ethnopharmacology. A biologically active compound derived from the plants may increase the effectiveness of antibiotic when used in combination. The present study aims to determine the synergistic antibacterial effect of ethanolic extracts of Punica granatum (pericarp), Commiphora molmol, Azadirachta indica (bark) in combination with amoxicillin, metronidazole, tetracycline, and azithromycin on periodontopathic bacteria: Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and Aggregatibacter actinomycetemcomitans. METHODOLOGY: Periodontopathic bacterial strains were isolated from the plaque sample that was collected from periodontitis patients and grown under favorable conditions. Susceptibility of bacteria to the antibiotics and extracts was determined by disc diffusion method by measuring the diameter of the inhibition zones. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of plant extracts were evaluated against each bacterium. Synergistic effect of plant extract in combination with antibiotics was tested against each bacterium by measuring the diameter of zone of inhibition (ZOI). RESULTS: Findings revealed that all plant extracts exhibited an inhibitory effects on the proliferation and growth of periodontopathic bacteria. The maximum antibacterial effect was exhibited by C. molmol on P. gingivalis (ZOI = 20 ± 0.55 mm, MIC = 0.53 ± 0.24 mg/mL and MBC = 5.21 ± 1.81 mg/mL) (p < 0.05), meanwhile, no antibacterial activity was exhibited by P. granatum on T. forsythia. Synergistic antibacterial effect was recorded when plant extracts were used in combination with antibiotics. The best synergism was exhibited by P. granatum with amoxicillin against A. actinomycetemcomitans (24 ± 1.00 mm) (p < 0.05). CONCLUSIONS: The synergistic test showed significant antibacterial activity when plant extracts were combined with antibiotics against all the experimented bacteria.

Effect of human secretory calcium-binding phosphoprotein proline-glutamine rich 1 protein on Porphyromonas gingivalis and identification of its active portions.

The mouth environment comprises the second most significant microbiome in the body, and its equilibrium is critical in oral health. Secretory calcium-binding phosphoprotein proline-glutamine rich 1 (SCPPPQ1), a protein normally produced by the gingival epithelium to mediate its attachment to teeth, was suggested to be bactericidal. Our aim was to further explore the antibacterial potential of human SCPPPQ1 by characterizing its mode of action and identifying its active portions. In silico analysis showed that it has molecular parallels with antimicrobial peptides. Incubation of Porphyromonas gingivalis, a major periodontopathogen, with the full-length protein resulted in decrease in bacterial number, formation of aggregates and membrane disruptions. Analysis of SCPPPQ1-derived peptides indicated that these effects are sustained by specific regions of the molecule. Altogether, these data suggest that human SCPPPQ1 exhibits antibacterial capacity and provide new insight into its mechanism of action.

A lingering mouthwash with sustained antibiotic release and biofilm eradication for periodontitis.

Dental plaque biofilms are believed to be one of the principal virulence factors in periodontitis resulting in tooth loss. Traditional mouthwashes are limited due to the continuous flow of saliva and poor drug penetration ability in the biofilm. Herein, we fabricated an antibiotic delivery platform based on natural polysaccharides (chitosan and cyclodextrin) as a novel mouthwash for the topical cavity delivery of minocycline. The penetration and residence mechanisms demonstrate that the platform can prolong the residence time up to 12 h on biofilms. Furthermore, sustained release can enhance the penetration of drugs into biofilms. In vitro antibiofilm experimental results indicated that the mouthwash effectively kills bacteria and eradicate biofilms. Effective treatment in vivo was confirmed by the significantly reduced dental plaque and alleviated inflammation observed in a rat periodontitis model. In summary, this novel platform can improve antibiofilm efficiency and prevent drugs from being washed away by saliva, which may provide benefits for many oral infectious diseases.

Personalized and Defect-Specific Antibiotic-Laden Scaffolds for Periodontal Infection Ablation.

Periodontitis compromises the integrity and function of tooth-supporting structures. Although therapeutic approaches have been offered, predictable regeneration of periodontal tissues remains intangible, particularly in anatomically complex defects. In this work, personalized and defect-specific antibiotic-laden polymeric scaffolds containing metronidazole (MET), tetracycline (TCH), or their combination (MET/TCH) were created via electrospinning. An initial screening of the synthesized fibers comprising chemo-morphological analyses, cytocompatibility assessment, and antimicrobial validation against periodontopathogens was accomplished to determine the cell-friendly and anti-infective nature of the scaffolds. According to the cytocompatibility and antimicrobial data, the 1:3 MET/TCH formulation was used to obtain three-dimensional defect-specific scaffolds to treat periodontally compromised three-wall osseous defects in rats. Inflammatory cell response and new bone formation were assessed by histology. Micro-computerized tomography was performed to assess bone loss in the furcation area at 2 and 6 weeks post implantation. Chemo-morphological and cell compatibility analyses confirmed the synthesis of cytocompatible antibiotic-laden fibers with antimicrobial action. Importantly, the 1:3 MET/TCH defect-specific scaffolds led to increased new bone formation, lower bone loss, and reduced inflammatory response when compared to antibiotic-free scaffolds. Altogether, our results suggest that the fabrication of defect-specific antibiotic-laden scaffolds holds great potential toward the development of personalized (i.e., patient-specific medication) scaffolds to ablate infection while affording regenerative properties.

Cold Atmospheric Plasma Jet as a Possible Adjuvant Therapy for Periodontal Disease.

Due to the limitations of traditional periodontal therapies, and reported cold atmospheric plasma anti-inflammatory/antimicrobial activities, plasma could be an adjuvant therapy to periodontitis. Porphyromonas gingivalis was grown in blood agar. Standardized suspensions were plated on blood agar and plasma-treated for planktonic growth. For biofilm, dual-species Streptococcus gordonii + P. gingivalis biofilm grew for 48 h and then was plasma-treated. XTT assay and CFU counting were performed. Cytotoxicity was accessed immediately or after 24 h. Plasma was applied for 1, 3, 5 or 7 min. In vivo: Thirty C57BI/6 mice were subject to experimental periodontitis for 11 days. Immediately after ligature removal, animals were plasma-treated for 5 min once-Group P1 (n = 10); twice (Day 11 and 13)-Group P2 (n = 10); or not treated-Group S (n = 10). Mice were euthanized on day 15. Histological and microtomography analyses were performed. Significance level was 5%. Halo diameter increased proportionally to time of exposure contrary to CFU/mL counting. Mean/SD of fibroblasts viability did not vary among the groups. Plasma was able to inhibit P. gingivalis in planktonic culture and biofilm in a cell-safe manner. Moreover, plasma treatment in vivo, for 5 min, tends to improve periodontal tissue recovery, proportionally to the number of plasma applications.

Multifunctional Ca-Zn-Si-based micro-nano spheres with anti-infective, anti-inflammatory, and dentin regenerative properties for pulp capping application.

While pulp capping using a variety of materials has been applied clinically to preserve the health and vitality of the dental pulp and induce dentin repair no material meets all the anti-infection, anti-inflammation, and promoting pulp tissue regeneration criteria. Micro-nano materials of bioactive glasses (BG) with the biocompatibility and osteogenesis-promoting properties were developed for this study using Zn-doped bioactive glass (BGz) micro-nano spheres for dental pulp capping to control infection and inflammation and promote tissue regeneration. Of three key findings, the co-culture of Porphyromonas gingivalis showed that the BGz had an excellent antibacterial effect, and after being stimulated with BGz in vitro, macrophages showed a significant decrease of pro-inflammatory M1 markers compared with the undoped BG group. It is also noted that the conditioned medium derived from BGz-stimulated macrophages could significantly promote mineralized dentin formation of dental pulp cells (DPCs). In rats, acute pulp restoration experiments proved that BGz used as a pulp capping agent had excellent dentin regenerative properties. This work may provide a novel strategy to promote osteo/dentinogenic differentiation through regulating early inflammation, with potential applications in pulp capping.

Effect of cranberry juice deacidification on its antibacterial activity against periodontal pathogens and its anti-inflammatory properties in an oral epithelial cell model.

Cranberries are widely recognized as a functional food that can promote oral health. However, the high concentration of organic acids in cranberry juice can cause tooth enamel erosion. Electrodialysis with bipolar membrane (EDBM) is a process used for the deacidification of cranberry juice. The present study investigated whether the removal of organic acids (0%, 19%, 42%, 60%, and 79%) from cranberry juice by EDBM affects its antibacterial activity against major periodontopathogens as well as its anti-inflammatory properties in an oral epithelial cell model. A deacidification rate ≥60% attenuated the bactericidal effect against planktonic and biofilm-embedded Aggregatibacter actinomycetemcomitans but had no impact on Porphyromonas gingivalis and Fusobacterium nucleatum. Cranberry juice increased the adherence of A. actinomycetemcomitans and P. gingivalis to oral epithelial cells, but reduced the adherence of F. nucleatum by half regardless of the deacidification rate. F. nucleatum produced more hydrogen sulfide when it was exposed to deacidified cranberry juice with a deacidification rate ≥42% compared to the raw beverage. Interestingly, the removal of organic acids from cranberry juice lowered the cytotoxicity of the beverage for oral epithelial cells. Deacidification attenuated the anti-inflammatory effect of cranberry juice in an in vitro oral epithelial cell model. The secretion of IL-6 by lipopolysaccharide (LPS)-stimulated oral epithelial cells exposed to cranberry juice increased proportionally with the deacidification rate. No such effect was observed with respect to the production of IL-8. This study provided evidence that organic acids, just like phenolic compounds, might contribute to the health benefits of cranberry juice against periodontitis.

Inhibitory effects of propolis and essential oils on oral bacteria.

INTRODUCTION: Propolis is a natural composite balsam. In the past decade, propolis has been extensively investigated as an adjuvant for the treatment of periodontitis. This study aimed to investigate antimicrobial activities of propolis solutions and plant essential oils against some oral cariogenic (Streptococcus mutans, Streptococcus mitis, Streptococcus sanguis, Lactobacillus acidophilus) and periodontopathic bacteria (Actinomyces odontolyticus, Eikenella corrodens, Fusobacterium nucleatum). METHODOLOGY: Determination of the minimum inhibitory concentration (MIC): The antimicrobial activity of propolis and essential oils was investigated by the agar dilution method. Serial dilutions of essential oils were prepared in plates, and the assay plates were estimated to contain 100, 50, 25 and 12.5 µg/mL of active essential oils. Dilutions for propolis were 50, 25, 12.5 and 6.3 µg/mL of active propolis solutions. RESULTS: Propolis solutions dissolved in benzene, diethyl ether and methyl chloride, demonstrated equal effectiveness against all investigated oral bacteria (MIC=12.5 µg/mL). Propolis solution dissolved in acetone displayed MIC of 6.3 µg/mL only for Lactobacillus acidophilus. At the MIC of 12.5 µg/mL, essential oils of Salvia officinalis and Satureja kitaibelii were effective against Streptococcus mutans and Porphyromonas gingivalis, respectively. For the latter, the MIC value of Salvia officinalis was twice higher. CONCLUSIONS: The results indicate that propolis and plant essential oils appear to be a promising source of antimicrobial agents that may prevent dental caries and other oral infectious diseases.

Role of ascorbic acid in the regulation of epigenetic processes induced by Porphyromonas gingivalis in endothelial-committed oral stem cells.

Periodontitis is a common inflammatory disease that affects the teeth-supporting tissue and causes bone and tooth loss. Moreover, in a worldwide population, periodontal disease is often associated with cardiovascular diseases. Emerging studies have reported that one of the major pathogens related to periodontitis is Porphyromonas gingivalis (P. gingivalis), which triggers the inflammatory intracellular cascade. Here, we hypothesized a possible protective effect of ascorbic acid (AA) in the restoration of the physiological molecular pathway after exposure to lipopolysaccharide derived from P. gingivalis (LPS-G). In particular, human gingiva-derived mesenchymal stem cells (hGMSCs) and endothelial-differentiated hGMSCs (e-hGMSCs) exposed to LPS-G showed upregulation of p300 and downregulation of DNA methyltransferase 1 (DNMT1), proteins associated with DNA methylation and histone acetylation. The co-treatment of AA and LPS-G showed a physiological expression of p300 and DNMT1 in hGMSCs and e-hGMSCs. Moreover, the inflammatory process triggered by LPS-G was demonstrated by evaluation of reactive oxygen species (ROS) and their intracellular localization. AA exposure re-established the physiological ROS levels. Despite the limitations of in vitro study, these findings collectively expand our knowledge regarding the molecular pathways involved in periodontal disease, and suggest the involvement of epigenetic modifications in the development of periodontitis.

Multifunctional chitin-based barrier membrane with antibacterial and osteogenic activities for the treatment of periodontal disease.

The guided tissue regeneration technique is an effective approach to repair periodontal defect. However, collagen barrier membranes used clinically lose stability easily, leading to soft tissue invasion, surgical site infection, and failure of osteogenesis. An ideal barrier membrane should possess proper antibacterial, osteoconductive activities, and favorable biodegradation. In this study, zinc oxide nanoparticles were homogeneously incorporated into the chitin hydrogel (ChT-1%ZnO) through one-step dissolution and regeneration method from alkaline/urea solution the first time. The remaining weights of ChT-1%ZnO in 150 µg/mL lysozyme solution was 52% after 5 weeks soaking. ChT-1%ZnO showed statistical antibacterial activities for P. gingivalis and S. aureus at 6 h, 12 h, and 24 h. Moreover, ChT-1%ZnO exhibits osteogenesis promotion in vitro, and it was further evaluated with rat periodontal defect model in vivo. The cemento-enamel junction value in ChT-1%ZnO group is 1.608 mm, presenting a statistical difference compared with no-membrane (1.825 mm) and ChT group (1.685 mm) after 8 weeks postoperatively.

Gingipain-Responsive Thermosensitive Hydrogel Loaded with SDF-1 Facilitates In Situ Periodontal Tissue Regeneration.

Existing local drug delivery systems for periodontitis suffer from poor antibacterial effect and unsatisfied periodontal regeneration. In this study, a smart gingipain-responsive hydrogel (PEGPD@SDF-1) was synthesized as an environmentally sensitive carrier for on-demand drug delivery. The PEGPD@SDF-1 hydrogel was synthesized from polyethylene glycol diacrylate (PEG-DA) based scaffolds, dithiothreitol (DTT), and a novel designed functional peptide module (FPM) via Michael-type addition reaction, and the hydrogel was further loaded with stromal cell derived factor-1 (SDF-1). The FPM exhibiting a structure of anchor peptide-short antimicrobial peptide (SAMP)-anchor peptide could be cleaved by gingipain specifically, and the SAMP was released out of the hydrogel for antibacterial effect in response to gingipain. The hydrogel properties were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), swelling ratio analysis, degradation evaluation, and release curve description of the SAMP and SDF-1. Results in vitro indicated the PEGPD@SDF-1 hydrogel exhibited preferable biocompatibility and could promote the proliferation, migration, and osteogenic differentiation of periodontal ligament stem cells (PDLSCs). Antibacterial testing demonstrated that the PEGPD@SDF-1 hydrogel released the SAMP stressfully in response to gingipain stimulation, thereby strongly inhibiting the growth of Porphyromonas gingivalis. Furthermore, the study in vivo indicated that the PEGPD@SDF-1 hydrogel inhibited P. gingivalis reproduction, created a low-inflammatory environment, facilitated the recruitment of CD90+/CD34- stromal cells, and induced osteogenesis. Taken together, these results suggest that the gingipain-responsive PEGPD@SDF-1 hydrogel could facilitate in situ periodontal tissue regeneration and is a promising candidate for the on-demand local drug delivery system for periodontitis.

Method for screening antimicrobial gels against multi-species oral biofilms.

We described a microtiter plate-based method that was effectively tailored for testing gel formulations against oral multispecies biofilms established on peg-lids. This method lifts the limitations imposed mainly by the anaerobic nature of the targeted bacterial species and the viscous properties of the targeted treatments.

In vitro degradation, biocompatibility and antibacterial properties of pure zinc: assessing the potential of Zn as a guided bone regeneration membrane.

Membrane exposure is a common complication after the guided bone regeneration (GBR) procedure and has a detrimental influence on the bone regeneration outcomes, while the commercially available GBR membranes show limited exposure tolerance. Recently, zinc (Zn) has been suggested as a promising material to be used as a barrier membrane in GBR therapy for bone augmentation. In this study, the degradation behavior in artificial saliva solution, cytotoxicity and antibacterial activity of pure Zn were investigated to explore its degradation and associated biocompatibility in the case of premature membrane exposure. The results indicated that the degradation rate of Zn in artificial saliva solution was about 31.42 µm year-1 after 28 days of immersion. The corrosion products on the Zn surface were mainly composed of Zn3(PO4)2, Ca3(PO4)2, CaHPO4, Zn5(CO3)2(OH)6 and ZnO. Besides, Zn presented an acceptable in vitro HGF cytocompatibility and a high antibacterial activity against Porphyromonas gingivalis. The preliminary results demonstrate that pure Zn exhibits appropriate degradation behavior, adequate cell compatibility and favorable antibacterial properties in the oral environment and is thus believed to sustain profitable function when membrane exposure occurs. The results provided new insights for understanding the exposure tolerance of Zn based membranes and are beneficial to their clinical applications.

A concerted probiotic activity to inhibit periodontitis-associated bacteria.

Periodontitis can result in tooth loss and the associated chronic inflammation can provoke several severe systemic health risks. Adjunctive to mechanical treatment of periodontitis and as alternatives to antibiotics, the use of probiotic bacteria was suggested. In this study, the inhibitory effect of the probiotic Streptococcus salivarius subsp. salivarius strains M18 and K12, Streptococcus oralis subsp. dentisani 7746, and Lactobacillus reuteri ATCC PTA 5289 on anaerobic periodontal bacteria and Aggregatibacter actinomycetemcomitans was tested. Rarely included in other studies, we also quantified the inverse effect of pathogens on probiotic growth. Probiotics and periodontal pathogens were co-incubated anaerobically in a mixture of autoclaved saliva and brain heart infusion broth. The resulting genome numbers of the pathogens and of the probiotics were measured by quantitative real-time PCR. Mixtures of the streptococcal probiotics were also used to determine their synergistic, additive, or antagonistic effects. The overall best inhibitor of the periodontal pathogens was L. reuteri ATCC PTA 5289, but the effect is coenzyme B12-, anaerobiosis-, as well as glycerol-dependent, and further modulated by L. reuteri strain DSM 17938. Notably, in absence of glycerol, the pathogen-inhibitory effect could even turn into a growth spurt. Among the streptococci tested, S. salivarius M18 had the most constant inhibitory potential against all pathogens, followed by K12 and S. dentisani 7746, with the latter still having significant inhibitory effects on P. intermedia and A. actinomycetemcomitans. Overall, mixtures of the streptococcal probiotics did inhibit the growth of the pathogens equally or-in the case of A. actinomycetemcomitans- better than the individual strains. P. gingivalis and F. nucleatum were best inhibited by pure cultures of S. salivarius K12 or S. salivarius M18, respectively. Testing inverse effects, the growth of S. salivarius M18 was enhanced when incubated with the periodontal pathogens minus/plus other probiotics. In contrast, S. oralis subsp. dentisani 7746 was not much influenced by the pathogens. Instead, it was significantly inhibited by the presence of other streptococcal probiotics. In conclusion, despite some natural limits such as persistence, the full potential for probiotic treatment is by far not utilized yet. Especially, further exploring concerted activity by combining synergistic strains, together with the application of oral prebiotics and essential supplements and conditions, is mandatory.