Voriconazole inhibits cross-kingdom interactions between Candida albicans and Actinomyces viscosus through the ergosterol pathway.

Candida albicans and Actinomyces viscosus are prominent microbes associated with dental root caries. The aim of this study was to investigate the effect of C. albicans on A. viscosus biofilms and to identify the mechanisms associated with this interaction. A. viscosus and C. albicans strains (wide-type and mutants) were used to form biofilms in vitro and in vivo, which were subsequently analysed by crystal violet assay and scanning electron microscopy (SEM) to investigate the effect of C. albicans on A. viscosus growth. A viable plate count and survival curve for C. albicans mutants and A. viscosus combinations were used to identify which C. albicans pathway was crucial for cross-kingdom interactions. Voriconazole was used to block their interactions both in vitro and in vivo. SEM, fluorescence in situ hybridisation (FISH), quantitative PCR and survival curve analyses were performed to evaluate the activity of voriconazole on C. albicans and A. viscosus interactions. The biomass and virulence of mixed-species biofilms were significantly enhanced compared with the A. viscosus biofilm alone. However, this was not observed in the mixed-species biofilms with the C. albicans mutant erg11Δ/Δ in vitro and in vivo, indicating that azoles may work on the mixed-species biofilms. As expected, voriconazole can effectively reduce the biomass of mixed-species biofilms. A high concentration of voriconazole (1 µg/mL) reduced the abundance of C. albicans, whilst a low voriconazole concentration (0.25 µg/mL) blocked their interactions similar to the effect of the erg11Δ/Δ mutant. Voriconazole may be a candidate strategy to combat root caries pathogens.

Optimization of Microwave-assisted Extraction of Essential Oil from Lavender Using Response Surface Methodology.

A microwave-assisted hydrodistillation (MAHD) method was investigated for extraction of essential oils from lavender. The essential oil extracts at optimized MAHD conditions was compared with hydrodistillation (HD). Response surface methodology coupled with Box-Behnken design was applied to optimize the parameters for MAHD. The optimized MAHD conditions were 500 W microwave power, 17 mL/g liquid-to-solid ratio and 40 min microwave time. The ANOVA results revealed that microwave time had the greatest impact on the essential oil yield followed by liquid-to-solid ratio and microwave power. Under the MAHD optimized conditions, the essential oil yield was 3.19%, approximating the predicted yield (3.20%). MAHD was superior in terms of saving energy and extraction time (40 min, compared to 120 min in HD). The essential oil analyzed by GC-MS, presented 39 compounds constituting 98.37% and 97.51% of the essential oils obtained through MAHD and HD, respectively. No obvious differences were found in composition between MAHD oil and HD oil. Antimicrobial study showed that the lavender essential oil exhibited broad-spectrum antibacterial activity and the MAHD oil showed a higher antimicrobial activity than the HD oil. This study revealed that MAHD could be a good method for extracting essential oil in lavender and other aromatic plants.

Antimicrobial Effect of an Experimental Glass lonomer Cement against Pathogens associated with Deep Carious Lesions.

AIM: To study the antimicrobial effect of chlorhexidine diacetate (CHX-D)-modified type II glass ionomer cement (GIC) against the two predominant deep caries microorganisms, namely Lactobacillus casei and Actinomyces viscosus. MATERIALS AND METHODS: An experimental GIC (ex-GIC) was prepared by mixing CHX-D powder with the powder of type II GIC to obtain 1% (w/w) concentration of CHX-D in the GIC. Antibacterial activity of this ex-GIC was tested against L. casei and A. viscosus using the agar diffusion method. The ex-GIC specimens were tested in their unset and set forms for each bacterium. For the unset group, specimens were placed in each agar plate immediately after manipulation and for the set group, specimens were placed in each agar plate, 1 hour after manipulation. The inhibition zones on the agar plate were recorded in millimeters immediately on placement of the specimen in the agar plate and after 48 hours. The reading was recorded and statistically analyzed for significant difference. RESULTS: Mann-Whitney U test showed statistically significant difference in the inhibition zones produced by ex-GIC against L. casei and A. viscosus when both were compared in unset (p-value = 0.002) and set (p-value = 0.031) groups. For both the groups, the zone of inhibition against L. casei was greater. Though the unset group recorded wider zone of inhibition, the difference was not significant when compared with the respective set group. This was true for both the bacterial groups. CONCLUSION: The 1% CHX-D-modified type II GIC showed antibacterial property against L. casei and A. viscosus and significantly higher activity against L. casei. CLINICAL SIGNIFICANCE: Addition of 1% CHX-D to type II GIC showed evidence of antibacterial activity against organisms found in deep carious lesion and therefore may exhibit superior antimicrobial efficiency when used as an intermediate therapeutic restoration in deep cavities.

Stannous Fluoride Effects on Gene Expression of Streptococcus mutans and Actinomyces viscosus.

A genome-wide transcriptional analysis was performed to elucidate the bacterial cellular response of Streptococcus mutans and Actinomyces viscosus to NaF and SnF2. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of SnF2 were predetermined before microarray study. Gene expression profiling microarray experiments were carried out in the absence (control) and presence (experimental) of 10 ppm and 100 ppm Sn2+ (in the form of SnF2) and fluoride controls for 10-min exposures (4 biological replicates/treatment). These Sn2+ levels and treatment time were chosen because they have been shown to slow bacterial growth of S. mutans (10 ppm) and A. viscosus (100 ppm) without affecting cell viability. All data generated by microarray experiments were analyzed with bioinformatics tools by applying the following criteria: 1) a q value should be ≤0.05, and 2) an absolute fold change in transcript level should be ≥1.5. Microarray results showed SnF2 significantly inhibited several genes encoding enzymes of the galactose pathway upon a 10-min exposure versus a negative control: lacA and lacB (A and B subunits of the galactose-6-P isomerase), lacC (tagatose-6-P kinase), lacD (tagatose-1,6-bP adolase), galK (galactokinase), galT (galactose-1-phosphate uridylyltransferase), and galE (UDP-glucose 4-epimerase). A gene fruK encoding fructose-1-phosphate kinase in the fructose pathway was also significantly inhibited. Several genes encoding fructose/mannose-specific enzyme IIABC components in the phosphotransferase system (PTS) were also downregulated, as was ldh encoding lactate dehydrogenase, a key enzyme involved in lactic acid synthesis. SnF2 downregulated the transcription of most key enzyme genes involved in the galactose pathway and also suppressed several key genes involved in the PTS, which transports sugars into the cell in the first step of glycolysis.

In vitro studies of the antimicrobial effect of non-thermal plasma-activated water as a novel mouthwash.

The aim of this study was to evaluate the antimicrobial effects of non-thermal plasma-activated water (PAW) as a novel mouthwash in vitro. Three representative oral pathogens - Streptococcus mutans, Actinomyces viscosus and Porphyromonas gingivalis - were treated with PAW. The inactivation effect was evaluated using the colony-forming unit (CFU) method, and the morphological and structural changes of a cell were observed by scanning electron microscopy and transmission electron microscopy (TEM). The physicochemical properties of PAW were analysed, and its influence on the leakage of intracellular proteins and DNA was evaluated. The results showed significant reduction of Streptococcus mutans within 60 s, of Actinomyces viscosus within 40 s, and of Porphyromonas gingivalis in less than 40 s. Scanning electron microscopy and TEM images showed that the normal cell morphology changed by varying degrees after treatment with PAW. Intracellular proteins (280 nm) and DNA (260 nm) leaked from all three species of bacteria after treatment with PAW. Reactive oxygen species (ROS), especially atomic oxygen (O), hydroxyl radical (˙OH), and hydrogen peroxide (H2 O2 ), were generated and led to strong oxidative stress and cell damage. These results suggest that PAW has potential use as a novel antimicrobial mouthwash.

Antimicrobial efficiency of mouthrinses versus and in combination with different photodynamic therapies on periodontal pathogens in an experimental study.

BACKGROUND AND OBJECTIVE: In the therapy of destructive periodontal disease, chemical antimicrobial agents and increasingly photodynamic therapy (PDT) play an important adjunctive role to standard mechanical anti-infective treatment procedures. However, both antiseptic methods have their shortcomings in terms of eliminating periodontal pathogens. The aim of the study was to compare the antibacterial efficacy of different antiseptic mouthrinses, of a conventional and a new, modified PDTplus as well as of the different antiseptic mouthrinses combined with either the conventional or the modified PDTplus against periopathogens. MATERIAL AND METHODS: Six representative periodontitis-associated bacterial strains were grown for 24 h under anaerobic conditions. After mixing the individual cell pellets they were exposed to 10 different antiseptic mouthrinse formulations: chlorhexidine (0.2%, 0.06%, CHX); CHX + cetylpyridinium chloride (each 0.05%); sodium hypochlorite (0.05%); polyhexanide (0.04%, PHMB1; 0.1%, PHMB2); octenidine dihydrochloride (0.1%); fluoride (250 ppm); essential oils; povidone iodine (10%); and saline (0.9%, NaCl) as control. Furthermore, the bacteria were treated with conventional PDT based on light-emitting diodes and a new modified photodisinfection combining photosensitizer with hydrogen peroxide to PDTplus also based on light-emitting diodes. In addition to the single treatments, a combined application of antiseptic exposure followed by use of PDT or PDTplus was performed. The microbial viability was characterized by analyzing colony growth and fluorescence-based vitality proportions. RESULTS: Nearly all mouthrinses caused a statistically significant growth inhibition. The most effective antiseptics, CHX (0.2%), CHX/cetylpyridinium chloride and octenidine dihydrochloride, inhibited bacterial growth completely. Conventional PDT resulted in moderate reduction of colony growth. The modified PDTplus achieved maximum antimicrobial effect. The combination of antiseptic exposure and PDT against periopathogens predominantly increased antibacterial efficacy compared to the single applications. The mouthrinse containing essential oil seemed to interfere with PDT. CONCLUSION: A combination therapy of preceding chemotherapeutical exposure and subsequent photodisinfection may be a more effective and promising antibacterial treatment than single applications of the antiseptic methods. The modified PDTplus using oxygen-enriched toluidine showed a superior antibacterial effect on periodontal pathogens to conventional PDT and to the majority of the investigated mouthrinses.

Design of a hydroxyapatite-binding antimicrobial peptide with improved retention and antibacterial efficacy for oral pathogen control.

Controlling and reducing the formation of pathogenic biofilm on tooth surface is the key to the prevention and treatment of the biofilm-associated oral diseases. Antimicrobial peptides (AMPs), considered as possible future alternatives for conventional antibiotics, have been extensively studied for the control of bacterial infection. Due to the rapid dilution and degradation by human saliva, AMP preparations designed for oral use with longer retention and higher efficacy are in urgent need. To this end, a hydroxyapatite (HAp)-binding antimicrobial peptide (HBAMP), which is based on the fusion of a specific HAp-binding heptapeptide (HBP7) domain and a broad-spectrum antimicrobial peptide (KSLW) domain, has been developed in our laboratory. HBAMP was supposed to form a contact-active antibacterial interface on tooth surface to inhibit the formation of biofilms. In this study, we investigated its binding behaviour, antibacterial activity against bacteria in both planktonic and sessile states, enzymatic stability in human saliva, and cytocompatibility to human gingival fibroblasts (HGFs). Our findings suggest that HBAMP could adsorb on tooth surface to provide effective antibacterial activity with improved retention. This study provides a proof-of-concept on using conjugated molecules to promote antibacterial efficacy by synergistically actions of HBAMP free in solution and bound on tooth surface.

Anti-plaque effect of a synergistic combination of green tea and Salvadora persica L. against primary colonizers of dental plaque.

OBJECTIVE: Green tea (Gt), leafs of Camellia sinensis var. assamica, is widely consumed as healthy beverage since thousands of years in Asian countries. Chewing sticks (miswak) of Salvadora persica L. (Sp) are traditionally used as natural brush to ensure oral health in developing countries. Both Gt and Sp extracts were reported to have anti-bacterial activity against many dental plaque bacteria. However, their combination has never been tested to have anti-bacterial and anti-adherence effect against primary dental plaque colonizers, playing an initial role in the dental plaque development, which was investigated in this study. METHODS: Two-fold serial micro-dilution method was used to measure minimal inhibitory concentration (MIC) of aqueous extracts of Gt, Sp and their combinations. Adsorption to hexadecane was used to determine the cell surface hydrophobicity (CSH) of bacterial cells. Glass beads were used to mimic the hard tissue surfaces, and were coated with saliva to develop experimental pellicles for the adhesion of the primary colonizing bacteria. RESULTS: Gt aqueous extracts exhibited better anti-plaque effect than Sp aqueous extracts. Their combination, equivalent to 1/4 and 1/2 of MIC values of Gt and Sp extracts respectively, showed synergistic anti-plaque properties with fractional inhibitory concentration (FIC) equal to 0.75. This combination was found to significantly reduce CSH (p<0.05) and lower the adherence ability (p<0.003) towards experimental pellicles. CONCLUSION: Combination between Gt and Sp aqueous extracts exhibited synergistic anti-plaque activity, and could be used as a useful active agent to produce oral health care products.

Antibacterial effect of composite resin foundation material incorporating quaternary ammonium polyethyleneimine nanoparticles.

STATEMENT OF PROBLEM: As caries is the most frequent cause of the failure of composite resin-based restorations, composite resins with antibacterial properties are desirable. However, whether quaternary ammonium polyethyleneimine nanoparticles can be effectively incorporated is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the antibacterial activity against Streptococcus mutans and Actinomyces viscosus of a foundation material incorporating quaternary ammonium polyethyleneimine (QPEI) nanoparticles. MATERIAL AND METHODS: QPEI antimicrobial nanoparticles were incorporated in a commercially available foundation material (Q Core; BJM Laboratories Ltd) at 1% wt/wt. Antibacterial efficacy against S mutans (106 colony-forming units [CFU]/mL) and A viscosus (106 CFU/mL) was examined by the direct contact test (DCT), and the agar diffusion test (ADT) with and without surface polishing. Bacterial outgrowth was recorded with a spectrophotometer. RESULTS: Growth of S mutans and A viscosus was inhibited, showing a decrease by 6 orders of magnitude in bacterial viability in specimens incorporating the nanoparticles, even after polishing the foundation material (P<.05). Growth inhibition was not observed in specimens without nanoparticles. CONCLUSIONS: Antibacterial properties can be achieved in a commercially available foundation material by incorporating polycationic antibacterial nanoparticles. This antibacterial effect did not diminish after surface polishing.

An in-vitro evaluation of antibacterial effect of Amalgomer CR and Fuji VII against bacteria causing severe early childhood caries.

OBJECTIVE: To evaluate the antibacterial action of Amalgomer CR and Fuji VII against bacteria causing S-early childhood caries. MATERIALS AND METHODS: Antibacterial activity of Amalgomer CR and Fuji VII was assessed using the agar diffusion test in triplicate. The powder and liquid of each test material was mixed and inserted in the punched wells (6 mm × 2 mm). A composition of 0.2% chlorhexidine digluconate acted as control. The agar plates were incubated at 37°C for 24 h for Streptococcus mutans, S. salivarius, S. parasanguinis and Actinomyces viscosus, whereas Lactobacillus casei was incubated for 48 h. Sizes of the inhibition zones were calculated by subtracting the diameter of the specimen (6 mm) from the average of the three measurements of the halo. For each test material against each bacteria, 9 measurements were made (3 measurements × 3 times). Kruskal-Wallis test was done to compare the zones of inhibition of test materials against individual bacteria. Pair-wise comparison was done by Mann-Whitney U-test. RESULTS: Amalgomer CR had the most antibacterial against S. mutans (31.0 mm), followed by A. viscosus (21.87 mm), S. salivarius (13.87 mm), S. parasanguinis (10.80 mm), and L. casei (9.69 mm). Fuji VII had the most antibacterial action against S. salivarius (10.65 mm), followed by A. viscosus (9.10 mm). However, it did not inhibit the growth of S. mutans (0 mm), S. parasanguinis (0 mm), and L. casei (0 mm). CONCLUSION: Amalgomer CR and Fuji VII showed wide variation in antibacterial action against all test organisms.

In vitro comparison of commercial oral rinses on bacterial adhesion and their detachment from biofilm formed on hydroxyapatite disks.

PURPOSE: This in vitro study was designed to assess the effectiveness of three oral rinses on bacterial adherence to epithelial cells and hydroxyapatite surfaces. The role of oral rinses on the detachment of bacteria from biofilm was also evaluated. MATERIALS AND METHODS: The efficacy of three oral rinses, Acclean, Noplak and Prevention were tested against a wide range of oral bacteria. Oral rinse antimicrobial activity was determined by an MTT assay for bacterial viability, by live/ dead staining and by measuring the bacterial metabolic activity using an XTT assay. RESULTS: The two oral rinses that contained 0.12% chlorhexidine had the greatest antibacterial activity on both planktonic and bio lm-grown organisms when compared to the Prevention oral rinse. CONCLUSION: Both Acclean and Noplak were extremely effective in lowering the number of bacteria attached to buccal epithelial cells and pelllicles. In addition, these two oral rinses were also effective against the biofilm bacteria.

Antibiotic resistance and capacity for biofilm formation of different bacteria isolated from endodontic infections associated with root-filled teeth.

INTRODUCTION: To date, a variety of microbial species have been isolated from endodontic infections. However, endodontic clinical bacterial isolates have not been sufficiently characterized with regard to their capacity for antibiotic resistance and biofilm formation. In this study, antibiotic resistance and biofilm formation of 47 different aerobic and anaerobic bacterial isolates, belonging to 32 different species previously isolated from infected filled root canals, were studied. METHODS: Antibiotic sensitivity to 11 antibiotics including penicillin G, amoxicillin, clindamycin, gentamicin, vancomycin, tetracycline, doxycycline, fosfomycin, rifampicin, ciprofloxacin, and moxifloxacin was tested using the standardized Etest method (Bio Merieux, Marcy-1'Etoile, France). The antibiotic sensitivity of 4 control strains was also estimated in parallel. Additionally, the capacity to form biofilms was quantified using the microtiter plate test. RESULTS: Different aerobic and anaerobic bacterial species were either resistant against a number of antibiotics or showed high minimal inhibitory concentrations against clinically relevant antibiotics. Five aerobic and 2 anaerobic isolates, including Enterococcus faecalis, Streptococcus mutans, Lactobacillus fermentum, Actinomyces naeslundii, Actinomyces viscosus, Prevotella buccae, and Propionibacterium acidifaciens, were characterized as being high biofilm producers, whereas 8 aerobic and 3 anaerobic isolates were found to be moderate biofilm producers. Most isolates with resistance or markedly high minimal inhibitory concentration values were also either moderate biofilm producers or high biofilm producers. CONCLUSIONS: These results suggest that the clinical significance of endodontic infections could include that they serve as a reservoir for antibiotic resistance. Furthermore, endodontic treatment should consider the adhesion and biofilm formation by a variety of bacteria.

Pro-oxidative synergic bactericidal effect of NO: kinetics and inhibition by nitroxides.

NO plays diverse roles in physiological and pathological processes, occasionally resulting in opposing effects, particularly in cells subjected to oxidative stress. NO mostly protects eukaryotes against oxidative injury, but was demonstrated to kill prokaryotes synergistically with H2O2. This could be a promising therapeutic avenue. However, recent conflicting findings were reported describing dramatic protective activity of NO. The previous studies of NO effects on prokaryotes applied a transient oxidative stress while arbitrarily checking the residual bacterial viability after 30 or 60min and ignoring the process kinetics. If NO-induced synergy and the oxidative stress are time-dependent, the elucidation of the cell killing kinetics is essential, particularly for survival curves exhibiting a "shoulder" sometimes reflecting sublethal damage as in the linear-quadratic survival models. We studied the kinetics of NO synergic effects on H2O2-induced killing of microbial pathogens. A synergic pro-oxidative activity toward gram-negative and gram-positive cells is demonstrated even at sub-µM/min flux of NO. For certain strains, the synergic effect progressively increased with the duration of cell exposure, and the linear-quadratic survival model best fit the observed survival data. In contrast to the failure of SOD to affect the bactericidal process, nitroxide SOD mimics abrogated the pro-oxidative synergy of NO/H2O2. These cell-permeative antioxidants, which hardly react with diamagnetic species and react neither with NO nor with H2O2, can detoxify redox-active transition metals and catalytically remove intracellular superoxide and nitrogen-derived reactive species such as (•)NO2 or peroxynitrite. The possible mechanism underlying the bactericidal NO synergy under oxidative stress and the potential therapeutic gain are discussed.

Incorporation of antimicrobial agents can be used to enhance the antibacterial effect of endodontic sealers.

AIM: The antibacterial activity of five endodontic sealers against three different microorganism strains alone and following incorporation of 2% benzalkonium chloride (BC) and 2% cetylpyridinium chloride (CPC) was evaluated. METHODOLOGY: The agar diffusion method was used to determine the inhibitory effect of the following endodontic sealers: RoekoSeal, Endomethasone N, N2, Apexit Plus and AH plus, on Streptococcus mutans - ATCC 25175, Lactobacillus casei - ATCC 4646 and Actinomyces viscosus - ATCC 19246. Bacterial strains were inoculated into BHIB, and incubated in an anaerobic atmosphere (37 °C). From the bacteria grown in the liquid medium, the density of the inoculum was set to be equivalent to McFarland 2 standard. In Shaedler agar, 350 µL of the bacterial suspension were equally spread. Specimens (4 mm × 6 mm) were prepared from each material without and with addition of 2% BC or 2% CPC. The inhibition zones were determined after 2 days, after 7 days and after 21 days of incubation. RESULTS: The largest inhibition zones were shown at zero time in all cases, with progressively less inhibition at 7 and 21 days. Endomethasone N and N2 showed the most intense antimicrobial activity, while RoekoSeal showed the least antimicrobial effect. The most susceptible microorganism was A. viscosus. Greater antimicrobial effects were found following incorporation of BC or CPC, and generally, BC gave greater inhibition zones than CPC. CONCLUSIONS: Adding either BC or CPC has the potential to improve clinical outcomes with endodontic sealers, as these substances enhance the short-term antimicrobial effects of the sealers.

Clinical and microbiological evaluation of the carious dentin before and after application of Papacarie gel.

OBJECTIVE: To evaluate clinically and microbiologically the efficacy of Papacarie in the removal of carious dentin in both permanent and primary teeth. STUDY DESIGN: Thirty permanent and primary molars with dentinal carious lesions were excavated and subjected to clinical and microbiological assessment before and after application of Papacarie. The gel was further tested for in vitro antimicrobial efficacy against standard cariogenic micro-organisms using agar diffusion assay. RESULTS: Papacarie was able to differentiate between infected and affected dentin clinically along with high patient comfort during caries excavation. The mean time taken for caries removal and restoration was observed to be 4.17 +/- 0.40 min. and 8.57 +/- 0.45 min. for permanent teeth and 4.21 +/- 0.36 min. and 9.24 +/- 0.58 min. for primary teeth. There was a significant reduction in the total viable colony forming units from the dentin samples before and after application of Papacarie. It was also observed that Papacarie had no inhibitory effect on standard cariogenic microorganisms in the agar diffusion assay. CONCLUSIONS: Papacarie is an effective caries removal method clinically in both permanent and primary teeth. The number of viable microorganisms after complete caries excavation using Papacarie still appears to be high and this bacterial count should be tackled by a suitable restorative material with potent antimicrobial activity.

[Preparation and antibacterial properties of nano-TiO(2-x)N(x) film].

OBJECTIVE: To prepare a nano-TiO2 film and characterize its antibacterial properties for dental application. METHODS: The TiO(2-x)N(x) antibacterial film was prepared by radio frequency (RF) magnetron sputtering. The crystal structure and surface morphology of the film were characterized by X-ray diffraction, scanning electron microscopy, and EDS, and the antibacterial properties of the film against common dental pathogenic bacteria were evaluated. RESULTS: The TiO(2-x)N(x) antibacterial film presented with an anatase phase with a mass ratio of nitrogen of 0.13% and compact and smooth surface. Antibacterial assay of the film showed a resistance rate of 97.79% against Streptococcus mutans, 49.42% against Actinomyces viscosus, and 96.84% against Candida albicans. CONCLUSION: The nano-TiO(2-x)N(x) film shows strong antibacterial effects against common dental pathogenic bacteria and can be used as a novel antibacterial dental material.

In vitro evaluation of MTAD and nisin in combination against common pathogens associated with root canal infection.

INTRODUCTION: Many pathogenic microorganisms were found in an infected root canal. The object of this study was to evaluate the effect of MTAD in combination with nisin on the pathogens associated with root canal infection. METHODS: The survival rates of 9 pathogenic bacteria were determined after 1-, 5-, and 10-minute treatment with MTAD, MTAN (substitution of doxycycline with nisin), and MTADN (nisin in combination with doxycycline). The survival rates of Enterococcus faecalis in the starvation phase and pretreatment alkalization as well as in the normal physiological state under MTAD, MTAN, and MTADN challenge for 1, 5, and 10 minutes were evaluated and compared. Furthermore, scanning electron microscopy was used to observe the morphologic modification of Actinomyces naeslundii, Lactobacillus paracasei, and Porphyromonas gingivalis after MTAD and MTADN treatment. RESULTS: L. fermenti, L. paracasei, A. viscosus, A. naeslundii, Streptococcus gordonii, and Peptostreptococcus were more sensitive to MTADN and MTAN than to MTAD. MTAD, MTAN, and MTADN showed a rapid antibacterial effect on P. gingivalis, Prevotella intermedia, and Fusobacterium nucleatum. Enterococcus faecalis in the stress state was as sensitive to MTAD, MTAN, and MTADN as the control E. faecalis. Furthermore, in the observation of scanning electron microscopy, the membranes in A. naeslundii and L. paracasei presented significant rupture, and P. gingivalis did not exhibit significant damage after MTADN treatment. CONCLUSIONS: MTAD in combination with nisin improved antibacterial efficacy against pathogens, especially for some gram-positive bacteria associated with persistent intracanal infection. Therefore, the combination had the potential to be used as an effective intracanal irrigation.

Clinical and microbiologic effects of commercially available dentifrice containing aloe vera: a randomized controlled clinical trial.

BACKGROUND: Certain plants used in folk medicine serve as a source of therapeutic agents that have antimicrobial and other multipotential effects. This prospective, randomized, placebo, and positively controlled clinical trial was designed to evaluate the clinical and microbiologic effects of a commercially available dentifrice containing aloe vera on the reduction of plaque and gingival inflammation in patients with gingivitis. METHODS: Ninety patients diagnosed with chronic generalized gingivitis were selected and randomly divided into three groups: group 1, placebo toothpaste; group 2, toothpaste containing aloe vera; and group 3, toothpaste with polymer and fluoride containing triclosan. Clinical evaluation was undertaken using a gingival index, plaque was assessed using a modification of the Quigley-Hein index, and microbiologic counts were assessed at baseline, 6 weeks, 12 weeks, and 24 weeks. A subjective evaluation was also undertaken by questionnaire. RESULTS: Toothpaste containing aloe vera showed significant improvement in gingival and plaque index scores as well as microbiologic counts compared with placebo dentifrice. These improvements were comparable to those achieved with toothpaste containing triclosan. CONCLUSION: Toothpaste containing aloe vera may be a useful herbal formulation for chemical plaque control agents and improvement in plaque and gingival status.

Antimicrobial activity of nanoemulsion on cariogenic planktonic and biofilm organisms.

INTRODUCTION: Nanoemulsions (NE) are a unique class of disinfectants produced by mixing a water immiscible liquid phase into an aqueous phase under high shear forces. NE have antimicrobial properties and are also effective anti-biofilm agents. MATERIALS AND METHODS: The effectiveness of nanoemulsion and its components was determined against Streptococcus mutans and Lactobacillus casei by live/dead staining. In vitro antimicrobial effectiveness of nanoemulsion against planktonic S. mutans, L. casei, Actinomyces viscosus, Candida albicans and mixed culture was determined by a serial dilution technique to obtain minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC). In addition, efficacy was investigated by kinetics of killing, adherence and biofilm assays. RESULTS: Compared to its components, nanoemulsion showed notable antimicrobial activity against biofilm organisms, up to 83.0% kill within 1min. NE dilutions ranging from 243 to 19683 were effective against planktonic S. mutans, L. casei, A. viscosus, C. albicans and mixed culture of these four strains as shown through MIC/MBC assays. NE showed antimicrobial activity against planktonic cells at high dilutions, confirmed by time kill studies. The level of adhesion on glass surface was reduced by 94.2-99.5% in nanoemulsion treated groups (p<0.001). 4-Day-old S. mutans, L. casei, A. viscosus, C. albicans and mixed cultures biofilms treated with NE showed reductions of bacterial counts with decreasing dilutions (p<0.001). CONCLUSION: These results suggest that nanoemulsion has effective anti-cariogenic activity against cariogenic microorganisms and may be a useful medication in the prevention of caries.

Antimicrobial sesquiterpenoids from Laurus nobilis L.

Activity-guided fractionations of leaf extracts from Laurus nobilis L. led to the isolation of a known sesquiterpene lactone, deacetyl laurenobiolide (1). Compound 1 showed antimicrobial activity against periopathic pathogens (Actinomyces viscosus, Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans), opportunistic Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes) and fungi (Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus). Furthermore, acetylation and cyclisation of deacetyl laurenobiolide (1) yielded laurenobiolide (2) and a new compound, (5S,6R,7S,8S,10R)-6,8-dihydroxyeudesma-4(15),11(13)-dien-12-oic acid 12,8-lactone (3), respectively. Compounds 2 and 3 also showed antimicrobial activities. All compounds 1-3 demonstrated growth inhibitory effects with minimum inhibitory concentrations ranging from 31 to 1000 µg mL(-1). This is the first report of compounds 1-3 showing antimicrobial activities.