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.

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.

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.

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.

[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.

Antibacterial activity of a triclosan-containing resin composite matrix against three common oral bacteria

This study investigated the antibacterial effect of a resin composite matrix with or without incorporated triclosan (0.3 wt%) on Streptococcus mutans, Actinomyces viscosus and Lactobacillus casei. In the quantitative assay, bacterial suspensions were filled into 20-μl cavities within temporary restorative resins. After 0, 4, 8, 12, 24 and 48 h of incubation, the suspensions were removed from the restoratives and the numbers of viable bacteria were determined. Bacterial suspensions incubated without restoratives served as the controls. Ten replicates were carried out for each experiment. The resin composite containing triclosan demonstrated variable degrees of antibacterial activity against the microorganisms, revealing a significant inhibitory effect on S. mutans within 12 h compared to the control. The viable counts of A. viscosus significantly decreased after 24 h. A significant reduction of L. casei was observed after 48 h. The unloaded resin composite did not reveal a marked antibacterial effect. The resin composite loaded with triclosan might be beneficial in preventing cavity contamination and minimizing the risk of pulpal irritation in the short-term.

Dammarane- and taraxastane-type triterpenoids from Saussurea oligantha Franch

A new dammarane triterpenoid oliganthas A (1) and a new taraxastane triterpenoid oliganthas B (2), as well as five known taraxastane triterpenoids, ptiloepoxide (3), taraxast-20(30)ene-3beta,21alpha-diol (4), 22-oxo-20-taraxasten-3beta-ol (5), taraxast-20-ene-3beta,30-diol (6), and taraxastane-3beta,20alpha-diol (7), were isolated from the whole plant of Saussurea oligantha Franch. Their structures were elucidated by a series of spectroscopic methods. These compounds, especially taraxastanes 2, 5, and 6, exhibited significant antibacterial activity against Actinomyces viscosus ATCC27044.

Effect of xylitol on an in vitro model of oral biofilm

PURPOSE

The aim of the present study was to examine whether xylitol, at different concentrations, inhibits the formation of an experimental model of oral biofilm.

MATERIALS AND METHODS

Biofilms of six bacterial species (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus rhamnosus, Actinomyces viscosus, Porphyromonas gingivalis and Fusobacterium nucleatum) were prepared on hydroxyapatite (HA) discs according to the Zürich Biofilm Model. Xylitol was tested at two concentrations, 1% and 3%. At the end of their designated incubation times, some HA discs were destined for confocal laser scanning microscopy (CLSM) and the others were harvested using a sterile surgical instrument. Aliquots of harvested biofilms were diluted and plated onto specific media. After a 48-h anaerobic incubation at 37 degrees C, the colony-forming units (CFUs) were counted.

RESULTS

CLSM images showed that only a small amount of isolated bacteria was observed on the surface of HA discs. Culture of harvested biofilms showed an inhibition in the growth of different species included in the biofilms.

CONCLUSIONS

Xylitol has a clear inhibitory effect on the formation of the experimental biofilms. This study shows that xylitol is not only efficient in inhibiting the acid production of cariogenic bacteria, but also in preventing the formation of a multispecies biofilm; it confirms the relevance of the use of this polyol for the prevention of oral diseases caused by dental plaque.

Activity of an antimicrobial peptide mimetic against planktonic and biofilm cultures of oral pathogens

Antimicrobial peptides (AMPs) are naturally occurring, broad-spectrum antimicrobial agents that have recently been examined for their utility as therapeutic antibiotics. Unfortunately, they are expensive to produce and are often sensitive to protease digestion. To address this problem, we have examined the activity of a peptide mimetic whose design was based on the structure of magainin, exhibiting its amphiphilic structure. We demonstrate that this compound, meta-phenylene ethynylene (mPE), exhibits antimicrobial activity at nanomolar concentrations against a variety of bacterial and Candida species found in oral infections. Since Streptococcus mutans, an etiological agent of dental caries, colonizes the tooth surface and forms a biofilm, we quantified the activity of this compound against S. mutans growing under conditions that favor biofilm formation. Our results indicate that mPE can prevent the formation of a biofilm at nanomolar concentrations. Incubation with 5 nM mPE prevents further growth of the biofilm, and 100 nM mPE reduces viable bacteria in the biofilm by 3 logs. Structure-function analyses suggest that mPE inhibits the bioactivity of lipopolysaccharide and binds DNA at equimolar ratios, suggesting that it may act both as a membrane-active molecule, similar to magainin, and as an intracellular antibiotic, similar to other AMPs. We conclude that mPE and similar molecules display great potential for development as therapeutic antimicrobials.

[Effects of traditional Chinese medicine on oral bacteria biofilm]

OBJECTIVE

To investigate the effects of compounds of Galla chinensis extract (GCE) and Nidus vespae extract-1 (WVE1) on oral bacteria biofilm structure and activity and to determine the possibility of caries prevention by the compounds.

METHODS

The morphology and activity of treated-oral bacterial biofilm and untreated-oral bacterial biofilm were observed by using fluorescence microscope in combination of idio-fluorochrome to label the died and living bacteria. The visible light semiquantitative method was used to measure biomass glucosyltransferase (GTF, A620) values and to determine the effects of active compounds of GCE and NVE1 on GTF of oral bacteria biofilm.

RESULTS

The living bacteria in the untreated 24 h bacterial biofilm was dominant, and only a small number of died bacteria were found, the biofilm structure was regular and clear. GCE, GCE-B and NVE1 could inhibit the bacteria in the dental biofilm, which showed significant difference with the negative control. GCE and NVE1 could also inhibit GTF activity of 24 h bacterial biofilm in comparison with the negative control.

CONCLUSIONS

The traditional Chinese medicine Galla chinensis and Nidus vespae could not only inhibit bacteria growth on oral bacterial biofilm, but also function by adjusting biofilm structure, composition and GTF activity of 24 h bacterial biofilm.

Surface antibacterial properties of glass ionomer cements used in atraumatic restorative treatment

BACKGROUND

Atraumatic restorative treatment (ART) is recommended for use worldwide, not only in developing countries where resources are not readily available, but also in more industrialized countries. The antibacterial properties of restorative dental materials may improve the restorative treatment outcome. Glass ionomer cement (GIC) has been advocated as the preferred restoration material for ART. The authors evaluated the antibacterial properties of restorative materials-three GICs and a zinc oxide eugenol (ZOE)-in vitro.

METHODS

Streptococcus mutans, Actinomyces viscosus and Enterococcus faecalis were the test microorganisms. The authors used a quantitative microtiter spectrophotometric assay to evaluate the antibacterial effect of the restorative materials using the direct contact test (DCT) of freshly prepared and one-week-aged materials.

RESULTS

The freshly prepared GICs and ZOE showed no bacterial growth in all tested bacteria compared with a control. This effect lasted for at least one week for S. mutans and A. viscosus but not for E. faecalis.

CONCLUSIONS

Conventional GICs used in ART showed antibacterial surface properties against cariogenic bacteria for at least one week. Further study on the long-term antimicrobial effects of GICs is needed.

CLINICAL IMPLICATIONS

The antimicrobial properties of freshly prepared restorative materials and aged restorative materials used in ART have a potent effect against cariogenic bacteria. These properties have crucial importance in preventing secondary caries.

In vitro inhibition of bacterial growth using different dental adhesive systems

OBJECTIVES

This study evaluated the antibacterial potential of four different adhesive systems.

METHODS & MATERIALS

Gluma Comfort Bond + Desensitizer, Gluma Comfort Bond, iBond and One-Up Bond F were tested against Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces viscosus. The inhibition of growth by calibrated preparations was quantified by the measurement of zones of inhibition on bacterial lawns. Bactericidal activity was determined as reductions in recoverable colony-forming units in bacterial suspensions exposed to test preparations.

RESULTS

All the preparations exhibited detectable zones of inhibition for all target bacteria through six months. When the bactericidal action was evaluated, all the materials were able to kill all the tested bacteria when tested immediately after polymerization. After one week of aging, iBond was the only material that continued to kill all of the test strains.

Antibacterial activity of four glass ionomer cements used in atraumatic restorative treatment

The in vitro antibacterial activity of four glass ionomer cements (Fuji IX, Ketac Molar, Vidrion R and Vitromolar) indicated for Atraumatic Restorative Treatment (ART) was studied against strains of bacteria involved in the development of oral diseases, Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces viscosus. The agar plate diffusion test was used for the cultures, which included chlorhexidine as a positive control. The results demonstrated that all the cements evaluated presented antibacterial activity. Based on the results of this study, it can be concluded that Fuji IX and Ketac Molar presented the most effective antibacterial activity considering the ART approach.

Antibacterial diterpenoids from Sagittaria pygmaea

There were five new diterpenoids, 18-beta-D-3',4'-diacetoxyxylopyranosyl-ent-kaur-16-ene (1), 18-beta-L-3',5'-diacetoxyarabinofuranosyl-ent-kaur-16-ene (2), 18-beta-D-3',6'-diacetoxyglucopyranosyl-ent-kaur-16-ene (3), ent-isopimar-8(14),15-dien-19-oic acid (4), and 5alpha-hydroxy-ent-rosa-15-en-18-oic acid (5), isolated from the whole herb of Sagittaria pygmaea. Their structures and relative configurations were established based on spectroscopic studies, chemical methods, and X-ray crystallographic analysis. Compound 2 exhibited significant antibacterial activity against the oral pathogens, Streptococcus mutans ATCC 25 175 and Actinomyces viscosus ATCC 27 044, with MIC values against both pathogens of 15.6 microg/mL. Compound 3 was active against only A. viscosus ATCC 27 044 with an MIC value of 62.5 microg/mL. Compounds 4 and 5 were active against S. mutans ATCC 25 175 and A. viscosus ATCC 27 044, with MIC values against both pathogens of 125.0 microg/mL.

An in vitro quantitative antibacterial analysis of amalgam and composite resins

OBJECTIVES

Antibacterial properties of restorative dental materials such as amalgam and composite resins may improve the restorative treatment outcome. This study evaluates the antibacterial properties of three composite resins: Z250, Tetric Ceram, P60 and a dental amalgam in vitro.

METHODS

Streptococcus mutans and Actinomyces viscosus served as test microorganisms. Three quantitative microtiter spectrophotometric assays were used to evaluate the effect of the restorative materials on: (i) early-stage biofilm using a direct contact test (DCT); (ii) planktonic bacterial growth; (iii) bacterial growth in the materials' elute. For comparison purposes, agar diffusion test (ADT) was also performed.

RESULTS

The effect of the composite resins on bacterial growth was minimal and limited to a few days only. One-week-aged composites promoted growth of S. mutans and A. viscosus. The antibacterial properties in direct contact were more potent than in planktonic bacterial growth. Amalgam showed complete inhibition of both bacteria in all phases, and the effect lasted for at least 1 week. The materials' elute had no effect on both bacterial growth with the exception of complete inhibition of S. mutans in amalgam. The later results correlated with the ADT.

CONCLUSIONS

The present findings demonstrate potent and lasting antibacterial properties of amalgam, which are lacking in composite resins. This may explain the clinical observation of biofilm accumulated more on composites compared to amalgams. It follows that the assessment of antibacterial properties of poorly-soluble materials has to employ more than one assay.

[Inhibition of extracts from 17 Chinese herbs on periodontal pathogenic microbes]

PURPOSE

To evaluate the efficiency of 17 Chinese herbs on periodontal pathogenic microbes.

METHODS

17 efficient substances from Chinese herbs were purchased from Chinese Drug Identification Bureau, including magnesium lithospermate B, magnolol, tetramethyl pyrazine, matrine, dycyrrhizin, gentiopicrin, aloperin, baicalin, oleanolic acid, ginkgo seed, total glucosides of paeony capsules, anisldehyde, archin, cablin patchouli, hydrochloric acid Berberine, forsythin, and kakonein. Antimicrobial sensitivity tests of broth microdilution methods on 96-microwell plate were carried out for identification of the antimicrobial activity of extracts against six species of microorganisms: Actinobacillus actinomycete mitans(Aa) Y4, Actinomycetes viscosus(Av) 19246, Porphyromonas gingivalis(Pg) 33277, Fusobacterium necrophorum(Fn) 25286, Actinomyces naeslundii(An) wvl 45 and Prevotella nigrescens(Pn).

RESULTS

It was found that magnesium lithospermate B and magnolol showed the most efficient inhibition on microorganism of Pn and Fn, with the MIC being 0.053 and 0.313 mg/ml for Pn and Fn, respectively. Tetramethyl pyrazine, matrine, dycyrrhizin, gentiopicrin, aloperin, baicalin, and oleanolic acid had better inhibition than total glucosides of paeony capsules, anisldehyde, archin, cablin patchouli, hydrochloric acid berberine, forsythin, and kakonein.

CONCLUSION

The Chinese herbs, magnesium lithospermate B and magnolol are efficient agents for inhibition against periodontal pathogenic microbes.

Effects of extracts of miswak and derum on proliferation of Balb/C 3T3 fibroblasts and viability of cariogenic bacteria

OBJECTIVES

This study examined the effects of extracts of two chewing sticks on proliferation of fibroblasts and viability of cariogenic bacteria.

METHODS

Aqueous extracts of miswak (Salvadora persica; Arak tree) and derum (Juglans regia; walnut tree) were prepared and their effects investigated on growth of Balb/C 3T3 mouse fibroblasts by measuring the mitochondrial succinic dehydrogenase activity. Furthermore, the effects on the viability of various cariogenic bacteria (Streptococcus mutans, Streptococcus salivarius, Lactobacillus casei and Actinomyces viscosus) was also determined.

RESULTS

The data revealed that Balb/C 3T3 fibroblasts exposed to aqueous extracts of miswak or derum showed an increase in cell proliferation by 156% and 255%, respectively, in comparison with controls (p < 0.0001). Furthermore, extracts from both miswak and derum had adverse effects on the growth of the cariogenic microorganisms, with derum having significantly greater antimicrobial effects than miswak and at much lower concentrations against all the bacteria tested. The most sensitive organisms were A. viscosus, followed by S. mutans, S. salivarius, with L. casei being the most resistant.

CONCLUSION

The results show that aqueous extracts of miswak and derum enhance the growth of fibroblasts and inhibit the growth of cariogenic bacteria, with the derum extract showing greater activity than miswak.

The antibacterial effects of zinc ion migration from zinc-based glass polyalkenoate cements

Zinc-based glass polyalkenoate cements have been synthesised and their potential use in orthopaedic applications investigated. Zinc ions were released from the materials in a rapid burst over the first 24 h after synthesis, with the release rate falling below detectable levels after 7 days. Cement-implanted bone samples were prepared and the released zinc was shown, using energy dispersive X-ray analysis, to penetrate from the cement into the adjacent bone by up to 40 microm. Finally, the cements exhibited antibacterial activity against Streptococcus mutans and Actinomyces viscosus that reflected the pattern of zinc release, with the inhibition of growth greatest shortly after cement synthesis and little or no inhibition measureable after 30 days.

In vitro antibacterial efficacy of a new chlorhexidine slow-release device

OBJECTIVE

The aim of this study was to evaluate and compare the antibacterial effect of chlorhexidine and calcium hydroxide slow-release devices on oral bacteria.

METHOD AND MATERIALS

The agar diffusion test was used to evaluate the antibacterial effect of the slow-release devices Activ Point (chlorhexidine; Roeko) and Calcium Hydroxide Plus Point (Roeko) on 8 anaerobic and 2 facultative oral bacterial strains, as well as 2 bacterial cultures randomly sampled from necrotic root canals and incubated in anaerobic and aerobic broth for 48 hours. The efficiency of the medicaments against the various strains was evaluated using a nonparametric test (Friedman type) and a second nonparametric test (Wilcoxon's signed rank test).

RESULTS

Activ Point produced significantly larger inhibition zones (P < .001) than the calcium hydroxide slow-release device around all tested bacterial strains.

CONCLUSION

The chlorhexidine slow-release device (Activ Point) exhibited significant antibacterial activity in the agar diffusion test and merits study as an intracanal medicament.

Inhibitory activity of glass-ionomer cements on cariogenic bacteria

This study evaluated the antibacterial activity of the glass-ionomer cements Vitrebond (3M ESPE), Ketac Molar (3M ESPE) and Fuji IX (GC America) against S mutans, S sobrinus, L acidophilus and A viscosus, using the agar diffusion test. Inocula were obtained by the seed of indicators cultures in BHI broth incubated at 37 degrees C for 24 hours. Base layers containing 15 mL of BHI agar and 300 microL of each bacteria suspension were prepared in Petri dishes. Six wells measuring 4 mm in diameter were made in each plate and completely filled with one of the testing materials. A 0.2% chlorhexidine solution applied in round filter papers was used as control. Tests were performed 12 times for each material and bacteria strain. After incubation of the plates at 37 degrees C for 24 hours, the zones of bacterial growth inhibition around the wells were measured. Overall, the results showed the following sequence of antibacterial activity: Vitrebond (despite the activation mode) > 0.2% chlorhexidine > Ketac Molar > Fuji IX, according to Kruskal-Wallis and Mann-Whitney statistical tests. This study confirmed significant antibacterial activity for two conventional glass-ionomers and one resin-modified glass-ionomer material. The resin-modified glass-ionomer cement Vitrebond, regardless of the activation mode, presented the best antibacterial activity against S mutans and S sobrinus. The antibacterial activity against A viscosus for Vitrebond was similar to 0.2% chlorhexidine, while light activation reduced its antibacterial activity against L acidophilus.

[An in vitro study on effect of Nidus vespae extract on the acid production of three strains of oral bacteria]

OBJECTIVE

To inquire into the effect of different of Nidus Vespae extract (NVE) on growth and acid production of Streptococcus mutans, Streptococcus sanguis and Actinomyces viscosus.

METHODS

Streptococcus mutans ATCC 25175, Streptococcus sanguis ATCC 10556 and Actinomyces viscosus ATCC 19246 were chosen as the experimental bacteria. Four extracts of Nidus Vespae were prepared and then the effects of these Nidus Vespae extracts on the acid production were determined.

RESULTS

All of Nidus Vespae extracts could inhibit the growth the of the three strains, and NVE1, NVE3, NVE4 could inhibit the acid production of the three strains, NVE2 could inhibit the acid production of Actinomyces viscosus.

CONCLUSION

Four extracts of Nidus Vespae could inhibit the acid production of three bacteria strains.

Effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria in vitro

BACKGROUND

Cecropin-XJ belongs to cecropin-B, which is the most potent antibacterial peptide found naturally. The aim of this study was to investigate the effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria.

METHODS

Four oral cariogenic bacteria (Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus and Actinomyces naeslundii) were chosen for this experiment. The minimal inhibitory concentrations (MICs) and reductive percent of bacterial growth were used to assay the antibacterial activity of cecropin-XJ. Mammalian cytotoxicity of cecropin-XJ was tested with human periodontal membrane fibroblasts by tetrazolium (MTT) colorimetric assay. The bacterial morphological changes induced by cecropin-XJ were examined on scanning electron microscope (SEM). The influence of cecropin-XJ on bacterial adhesion to saliva-coated hydroxyapatite (S-HA) was measured by scintillation counting.

RESULTS

The MICs of cecropin-XJ for inhibition of the growth of four bacteria ranged from 4.0 to 42.8 micromol/L with the highest susceptible to A. naeslundii and the lowest susceptible to L. acidophilus. At pH 6.8, 5.5 and 8.2, 1/2 MIC of cecropin-XJ reduced the number of viable bacteria by 40.9%, 67.8% and 32.8% for S. mutans and by 28.1%, 57.2% and 37.9% for L. acidophilus. The activities against S. mutans and L. acidophilus increased at pH 5.5 compared with pH 6.8 (P < 0.01, respectively). In present of 50% saliva, 1/2 MIC of the peptide decreased the direct count of viable cells by 29.2% and 14.4% for S. mutans and L. acidophilus, respectively (P < 0.01 and P > 0.05, respectively), whereas almost no reduction counts were detected in the presence of 20% serum for both bacteria (P > 0.05, respectively). Mammalian cytotoxicity of cecropin-XJ from 1.0 to 100 micromol/L exhibited no cytotoxicity against human periodontal membrane fibroblasts (P > 0.05). Bacterial morphological changes induced by MIC of cecropin-XJ examined on SEM showed cell surface disruption. Furthermore, the ability of A. naeslundii adhesion to S-HA decreased significantly with MIC of cecropin-XJ for 10 and 20 minutes (P = 0.001 and 0.000, respectively), and S. mutans, A. viscosus to S-HA decreased significantly with MIC of cecropin-XJ for 20 minutes (P = 0.000, respectively).

CONCLUSIONS

Cecropin-XJ exhibited bactericidal action against cariogenic pathogens, and the antibacterial activity enhanced in the acid environment. The results also demonstrate that cecropin-XJ prevents S. mutans and actinomyces adsorption to S-HA. These findings suggest that Cecropin-XJ may have potential to prevent caries.

A simple approach to examine early oral microbial biofilm formation and the effects of treatments

BACKGROUND/AIMS

A simple in vivo approach to examine early dental plaque formation in the human mouth and to determine the effects of common dietary and oral hygiene procedures on biofilm formation is reported.

METHODS

A custom designed device that fits securely behind the teeth of the mandibular arch provides a surface for microbial colonization. This device is prepared with denture acrylic and can be repeatedly used by the subject, exposing a large and constant surface area for microbial accumulation.

RESULTS

Large numbers of oral bacteria colonized the device by 2 h; these increased significantly by 4 h (P < 0.05). Bacterial colonization increased significantly after rinsing with a sucrose solution (P < 0.05) but remained unaffected after rinsing with water, a commercially available fluoride mouthrinse without antimicrobial agents, or brushing with a fluoride dentifrice (P > 0.05). Rinsing with mouthrinses formulated with chlorhexidine, cetylpyridinium chloride or triclosan/copolymer significantly inhibited colonization (P < 0.05). A dose-dependent inhibition was noted with chlorhexidine rinses (P < 0.05). Brushing with a triclosan/copolymer dentifrice significantly inhibited microbial colonization compared with a control (P < 0.05).

CONCLUSION

This simple approach was useful for examining the effects of common dietary and oral hygiene procedures. Significant biofilm inhibitory effects were noted with formulations that demonstrated efficacy in previous clinical studies.

Effects of low dose chlorhexidine mouthrinses on oral bacteria and salivary microflora including those producing hydrogen sulfide

BACKGROUND/AIMS

Clinical studies have demonstrated the considerable effects of chlorhexidine on dental plaque and oral microbiota as well as improvements in indices of oral health. This investigation examined the efficacy of lower concentrations of chlorhexidine.

METHODS

Mouthrinses with 0.03%, 0.06%, 0.12% chlorhexidine and a control rinse without chlorhexidine were examined. Alamar blue, an oxidation-reduction dye with fluorescent end-points proportional to bacterial viability, was used to determine bacterial viability. Further clinical studies examined the effects of these rinses on salivary bacteria and on bacteria producing hydrogen sulfide (H(2)S) and implicated in halitosis.

RESULTS

In laboratory tests, a significant dose-dependent effect was observed with Actinomyces viscosus as a model system using the Alamar blue procedure (P < 0.05). Clinical studies examined the effects 1.5 h and 3 h post-treatment on salivary bacteria and bacteria producing H(2)S. The first study compared the control rinse with the 0.03% and 0.06% chlorhexidine rinses; a second study compared the effects of the control rinse and the 0.06% and 0.12% chlorhexidine mouthrinses. In both studies, chlorhexidine rinses demonstrated significant dose-dependent effects post-treatment on salivary bacteria vs. the control rinse (P < 0.05). Significant decreases in H(2)S-producing bacteria were noted with these chlorhexidine rinses vs. the control rinse (P < 0.05).

CONCLUSION

The results highlight the dose-dependent relationships noted in laboratory and clinical tests which have potential implications for the use of lower doses of chlorhexidine to inhibit oral bacteria, including those implicated in halitosis.

Antimicrobial effects of a new therapeutic liquid dentifrice formulation on oral bacteria including odorigenic species

The control of oral malodor is well-recognized in efforts to improve oral health. Antimicrobial formulations can mitigate oral malodor, however, procedures to assess effects on oral bacteria including those implicated in halitosis are unavailable. This investigation examined the antimicrobial effects of a new liquid triclosan/copolymer dentifrice (test) formulation that demonstrated significant inhibition of oral malodor in previous organoleptic clinical studies. Procedures compared antimicrobial effects of the test and control formulations on a range of oral micro-organisms including members implicated in halitosis, substantive antimicrobial effects of formulations with hydroxyapatite as a surrogate for human teeth and ex vivo effects on oral bacteria from human volunteers. With Actinomyces viscosus, as a model system, the test formulation demonstrated a dose-dependent effect. At these concentrations the test formulation provided significant antimicrobial effects on 13 strains of oral bacteria including those implicated in bad breath at selected posttreatment time points. Treatment of hydroxyapatite by the test dentifrice resulted in a significant and substantive antimicrobial effect vs. controls. Oral bacteria from subjects treated ex vivo with the test dentifrice resulted in significant reductions in cultivable oral bacteria and odorigenic bacteria producing hydrogen sulfide. In summary, microbiological methods adapted to study odorigenic bacteria demonstrate the significant antimicrobial effects of the test (triclosan/copolymer) dentifrice with laboratory and clinical strains of oral bacteria implicated in bad breath.

Antibacterial activity of silver inorganic agent YDA filler

YDA filler is an antibacterial agent that is currently in commercial dental use. In this study, we attempted to determine whether it exerts an antibacterial effect on human saliva bacteria, and to determine whether it can be used in dental materials. CFUs in 1 mL stimulated human saliva were examined using blood agar and mitis salivarius agar after immersion, with or without YDA filler. The antibacterial effect was compared with that of Ketac-Silver. Dental materials containing 5% wt YDA filler were prepared for in vitro testing on S. mutans and A. viscosus. Furthermore, we examined the in vitro cytotoxicity of experimental MMA resin containing YDA filler on HeLa cells. Human saliva bacteria and mutans streptococci showed reduced viability following exposure to YDA filler after 12 h. The concentration of silver ions released by YDA filler was below 1 ppm after 12 h. Two tested strains showed reduced viability following exposure to dental materials containing YDA filler. In another experiment, MMA resin containing YDA filler did not show cytotoxicity on HeLa cells after 24- and 48-h exposure. Thus, YDA filler may help in the development of antibacterial dental materials, such as composite resin, glass-ionomer or temporary cement.

The antimicrobial potential of 14 natural herbal dentifrices

BACKGROUND

Increasing numbers of Americans are using natural herbal products for general and oral health care. Few of these products, however, have undergone rigorous testing, as evidenced by the limited amount of information on their safety and efficacy in the literature. The authors conducted an in vitro study to evaluate the antimicrobial potential of 14 natural herbal dentifrices.

METHODS

The authors used a diffusion method to evaluate the antimicrobial effectiveness of 14 natural herbal dentifrices against four microorganisms: Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus and Candida albicans. Colgate Total (Colgate-Palmolive, New York City) and sterile pyrogen-free water served as the positive and negative controls, respectively. The authors tested the natural herbal dentifrices at full strength and at 1:1 dilution. They measured the zones of inhibition at 24 and 48 hours to evaluate the antimicrobial potential of the dentifrices.

RESULTS

Six herbal dentifrices were effective in inhibiting the growth of all four microorganisms. The positive control produced significantly sized inhibition zones with all four microorganisms, while the negative control produced no observable zones. Six herbal dentifrices produced larger inhibition zones with A. viscosus than did the positive control. Six herbal dentifrices were inhibitory against C. albicans at full strength, but at 1:1 dilution, only three had such inhibitory effect. One herbal dentifrice produced microbial growth around and over the samples, indicating possible microbial contamination of the toothpaste. Only one herbal dentifrice showed consistent antimicrobial activity against all four microorganisms.

CONCLUSIONS

The variation in antimicrobial inhibition among the herbal dentifrices indicates that more research is needed to validate their effectiveness claims.

CLINICAL IMPLICATIONS

This study provides practitioners with insight into the claims of natural herbal dentifrices' antimicrobial effects.

A rapid procedure to ascertain the antimicrobial efficacy of oral care formulations

A rapid method examining the antimicrobial efficacy of oral care formulations with alamar blue, an oxidation-reduction dye with fluorescent end-points, is described. Significant correlations between increasing viable plate counts of the oral bacteria Actinomyces viscosus, Streptococcus sanguis, Streptococcus mutans and Actinobacillus actinomycetemcomitans and increased alamar fluorescence were noted. Metabolically active bacteria reduced alamar with the reduced dye found in the cell-free filtrate. Insignificant alamar reductions were noted in the absence of bacteria or by spent culture supernatants. The efficacy of mouthrinses with clinically proven antiplaque agents such as chlorhexidine or cetylpyridinium chloride were determined by alamar blue. In a model system with A. viscosus, triclosan dentifrices demonstrate a dose-dependent effect on bacteria. Human salivary bacteria demonstrate increasing alamar fluorescence with increasing plate counts. A clinical study examined the effects of rinsing with chlorhexidine or cetylpyridinium chloride mouthrinses in comparison with a placebo mouthrinse and water on salivary bacteria. Rinsing with chlorhexidine resulted in the least number of bacteria by alamar and plate count methods. In summary, the current study demonstrates the utility of alamar blue to examine the antimicrobial effects of oral care formulations in laboratory and clinical studies.

[Effect of para-aminobenzonic acid on cell-surface hydrophobicity of Actinomyces viscosus]

OBJECTIVE

To study the effect of Para-aminobenzonic acid (PABA) on cell-surface hydrophobicity of Actinomyces viscosus.

METHODS

Microbial adhesion to hydrocarbons (MATH) was used to measure the cell-surface hydrophobicity of Actinomyces viscosus which grew in modified Carlsson medium with different dilution of PABA.

RESULTS

Following the increase of concentration of PABA, the value of cell-surface hydrophobicity of Actinomyces viscosus decreased, which were 0.38900 +/- 0.00026, 0.25462 +/- 0.00168, 0.16360 +/- 0.00026 respectively(P < 0.05).

CONCLUSION

PABA could inhibit the adherence of Actinomyces viscosus by way of changing its cell-surface hydrophobicity.

Effect of sustained-release chlorhexidine varnish on Streptococcus mutans and Actinomyces viscosus in orthodontic patients

This study evaluated the effect of sustained-release chlorhexidine varnish on orthodontic patients. Ten children, ages 10 to 16 years, participated. Bacterial levels of Streptococcus mutans and Actinomyces viscosus and total counts were evaluated in sputum samples. These counts were evaluated at 4 stages: before orthodontic treatment, at least 2 weeks after bonding of the brackets, 1 week after application of chlorhexidine varnish, and 3 weeks after application of chlorhexidine varnish. Increases in bacterial levels of S mutans and in the total bacterial count were detected after the brackets were bonded. One week after the sustained-release chlorhexidine varnish was applied, a significant decrease of total bacterial levels and S mutans was observed. This decrease persisted for 3 weeks after the first application. No significant change in A viscosus levels occurred during that period. The results provide additional evidence that sustained-release chlorhexidine varnish decreases S mutans levels in orthodontic patients with fixed appliances and therefore might be useful in preventing caries lesions.

Effects of selected immunouppressive drugs on prostaglandin release, protein synthesis and cell proliferation in human gingival fibroblasts and on the growth of plaque bacteria

BACKGROUND

Immunosuppressants play an essential role in transplantation therapy. In view of the side effects, e.g. gingival overgrowth, the present in vitro study was performed in order to investigate the effect of selected immunosuppressants on metabolic activities of gingival fibroblasts. Furthermore, the effect on the growth of six oral microorganisms was investigated.

METHODS

Human gingival fibroblasts were incubated in the presence of azathioprine (Aza), cyclosporin A (CsA), tacrolimus (Tac) or mycophenolatmofetil (Myc). PGE subset 2 release was determined by means of a specific competitive enzyme immunoassay, using monoclonal antibodies specific for PGE subset 2 (clone E2R1). The protein content was measured spectrophotometrically. A redox indicator system was employed to assess the proliferation activity. In an additional trial the growth of six strains of oral bacteria (A. viscosus T14V, S. oralis H1, S. mutans 10449, C. gingivalis DR2001, A. actinomycetemcomitans Y4, and M. micros 33270) in the presence of the immunosuppressants was measured.

RESULTS

In comparison with the controls, the PGE subset 2 release was increased by 39.3% following incubation with Aza, and by 77.0% with CsA. The protein concentrations (1 g immunosuppressant / ml medium) were reduced by 26.0% for Aza and 17.0% for Myc. Furthermore, a drug-dependent inhibition in the cell proliferation rate was noted after an incubation period of 6 hours (Aza 70.7%, CsA 78.2%, Myc 69.8%, Tac 64.0%). The most pronounced growth-inhibiting effects were observed for CsA at values ranging from 21.0% (S. mutans 10449) to 48.6% (A. viscosus T14V) growth inhibition.

CONCLUSIONS

The present study with common immunsuppresants demonstrated both a medication- and dose-dependent alteration in the metabolic activity of gingival fibroblasts. Furthermore, growth-inhibitory effects on the selected bacterial strains could be observed.

Comparison of antibacterial activity of simplified adhesive systems

PURPOSE

To determine and compare the intrinsic antibacterial activity of commercially available simplified adhesive systems.

MATERIALS AND METHODS

The antibacterial activity of five self-etching/priming one-step adhesives and three priming/bonding adhesives against Streptococcus mutans, Lactobacillus casei, and Actinomyces viscosus was assessed by the agar disc-diffusion test and determination of the minimum inhibitory/bactericidal concentration (MIC/MBC). Twenty microl of each adhesive was impregnated into a paper disc and placed on an agar plate inoculated with a bacterial suspension, with or without light-irradiation. The size of inhibition zones produced around the specimens was measured after 48 hours of incubation. The MIC values were measured by serial microdilution assays, visually examining the growth of bacteria after incubation with each adhesive for 24-48 hours. The subcultures were made on BHI agar plates from the wells showing no visible growth of bacteria, and the MBC values were determined based on production of colonies. Two primers in two-step self-etching systems and an experimental primer containing chlorhexidine were tested for reference. The results of disc-diffusion tests were analyzed by ANOVA and Fisher's PLSD test.

RESULTS

The size of inhibition zones produced by adhesives varied among the brands. None of the available commercial adhesives showed significant inhibition against all three of the bacterial species tested. Light-irradiation reduced the size of inhibition zones for a few materials, but a similar trend to the effectiveness of non-irradiated specimens was observed. The antibacterial activity of commercial products determined in terms of MIC/MBC values were different from the results by disc-diffusion tests. The self-etching adhesives with low pH were not necessarily more effective than priming/bonding solutions, and no significant relationships between the acidity and antibacterial effects were found. Compared with commercial products, an experimental primer containing chlorhexidine produced significantly larger inhibition zones against all species (P < 0.05) and exhibited greater bacteriostatic/bactericidal activity, demonstrating lower MIC/MBC values.

[The in vitro study of the effects of 11 kinds of traditional Chinese medicine on the growth and acid production of Actinomyces viscosus]

OBJECTIVE

To assess the effects of different natural medicines on the growth and acid production of Actinomyces viscosus, thus making preparations for screening an effective agent to mediate the balance of oral microflora.

METHODS

Actinomyces viscosus ATCC 19246 was chosen as the experimental bacteria. 11 kinds of traditional Chinese medicine, such as Rhizoma Ligustici Chuanxiong, Sargentodoxa Cuneata and Galla Chinensis were extracted by means of maceration, percolation and reflux extraction. First, the values of MIC of various extracts were measured. Second, the experimental medium containing various extracts was prepared. The concentration of the extracts was lower than the MIC of the medicine, and the initial pH of the medium was 7.4. Then Actinomyces viscosus was cultured in the medium for 48 h, and finally the rest pH was measured.

RESULTS

When the concentration of the medicines was lower than or equal to 8.000 mg/ml, it was found that all kinds of medicine except Radix Notoginseng can inhibit the growth of Actinomyces viscosus effectively, especially Polistes mandarinus and Semen Arecae. Tea polyphenols, Radix Notoginseng, Radix et Rhizoma Rhei, Polistes mandarinus and Sargentodoxa cuneata can inhibit the acid production of Actinomyces viscosus effectively, but Radix Scutellariae, Rhizoma Ligustici Chuanxiong, Semen Arecae, Radix Angelicae Dahuricae, Galla Chinensis and Catechu have no preliminary effect on it.

CONCLUSION

Tea polyphenols, Radix et Rhizoma Rhei, Polistes mandarinus and Sargentodoxa cuneata can inhibit the growth and the acid production of Actinomyces viscosus effectively.

[Effect of para-aminobenzoic acid on the growth of Actinomyces viscosus]

OBJECTIVE

To examine the effects of para-aminobenzoic acid (PABA) on the growth of Actinomyces viscosus.

METHODS

Different concentrations of PABA (10(-10)-10(-3) g/L) were each transferred to modified Carlsson medium. Actinomyces viscosus ATCC19246 grew in them. And the cultures were incubated at 37 degrees C anaerobically in the atmosphere of 80%N2, 10%H2, 10%CO2 for 48 h. Actinomyces viscosus OD values (lambda = 540 nm) were obtained with UV-1601. Colony forming unit (CFU) was established by growth of Actinomyces viscosus in culture when different concentrations of PABA (10(-10)-10(-3) g/L) were present.

RESULTS

Different concentrations of PABA (10(-10)-10(-4) g/L) had different stimulating effects on the growth of Actinomyces viscosus (P < 0.05). But this kind of stimulating effect declined when PABA concentration was 10(-5) g/L, and as PABA (10(-3) g/L) was present, this kind of effect was missing.

CONCLUSION

The phenomena indicated that PABA has stimulating effect on the growth of Actinomyces viscosus, particularly when PABA is at the concentration of 10(-6) g/L.

The antimicrobial properties of a urea-based handwash lotion with triclosan

The purpose of this study was to determine and compare the antimicrobial action of a urea-based handwash lotion with triclosan with a lipid-depleting detergent-based handwash product with 4% chlorhexidine gluconate. The zones of inhibition produced by the two handwash lotions and the one produced by the positive control were similar against all strains of bacteria tested, indicating that a urea-based handwash lotion with triclosan is as effective as a lipid-depleting handwash lotion in inhibiting bacterial activity.

Effects of three different infant dentifrices on biofilms and oral microorganisms

The purpose of this work was to evaluate the effects of infant dentifrices: A--with lactoperoxidase, glucose oxidase and lactoferrin; B--with 1100 ppm of NaF and sodium lauryl sulfate; C--with extract of calendula. The dentifrices were test on biofilms formed in vitro from saliva and dental plaque of infants, using reference strains A. viscosus (ATCC 43146); C. albicans (ATCC 51501); L. casei (ATCC 4646); S. mitis (ATCC 49456); S. mutans (ATCC 25175); S. oralis (ATCC 35037); S. sanguis (ATCC 10586); S. sobrinus (ATCC 27609) and isolated clinically microorganisms C. albicans, S. mitis, S. mutans, S. oralis, S. sanguis, S. sobrinus and Lactobacillus sp. Twenty infants were chosen, who were beginning treatment at the Infants Clinic of the Pediatric Dentistry Department, Federal University of Rio de Janeiro. A pool of unstimulated saliva and a pool of dental plaque were collected from which biofilms were produced. Supernatants from each dentifrice were prepared and concentrated and diluted solutions of the dentifrices and a control sterile diluent were tested against the biofilms produced, for 1 and 3 minutes, and against the microorganisms. The results were statistically analyzed by the ANOVA and Tukey Test. After the exposure of the biofilms produced both from saliva and from dental plaque, to the dentifrice B concentrated and 1/2, for 1 and 3 minutes, the viable microorganisms count (CFU/ml), compared to the controls, was significantly reduced (p < 0.05). However, exposure to the dentifrices A and C concentrated and dentifrice B 1/4 and 1/8, for 1 and 3 minutes, was not significantly lethal to the biofilms. The dentifrices A and C, either concentrated or diluted (1/2 to 1/128) and the dentifrice B in the dilutions 1/16 to 1/128 did not have an antimicrobial effect on any microorganism evaluated. For all the microorganisms evaluated, the dentifrice B concentrated and in the 1/2 dilution showed a significant antimicrobial effect, when compared with the control (p < 0.05).

Antibacterial activity of particulate Bioglass® against supra- and subgingival bacteria

Particulate Bioglass is a bioactive material used in the repair of periodontal defects. This material undergoes a series of surface reactions in an aqueous environment which lead to osseointegration. The aim of this study was to determine whether these reactions exerted an antibacterial effect on a range of oral bacteria. Streptococcus sanguis, Streptococcus mutans and Actinomyces viscosus were suspended in nutrient broth (NB), artificial saliva (AS) or Dulbecco's modified eagle medium plus 10% foetal calf serum (DMEM + 10%FCS), with or without particulate Bioglass. All bacteria showed reduced viability following exposure to Bioglass in all the media after 1 h. This antibacterial effect increased after 3 h. Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia and Actinobacillus actinomycetemcomitans were suspended in either BM broth or 40% horse serum (HS) in RPMI. A considerable reduction in viability was observed with all bacteria tested, in both media, compared to inert glass controls. In further experiments it was found that the viability of S. sanguis was significantly reduced following exposure to NB pre-incubated with Bioglass. Additionally, it was found that neutralisation of this highly alkaline solution eliminated the antibacterial effect. Moreover, a solution of NB and NaOH (of equivalent pH) exerted an antibacterial effect of similar magnitude to that of the solution pre-incubated with Bioglass. Thus, particulate Bioglass exerts an antibacterial effect on certain oral bacteria, possibly by virtue of the alkaline nature of its surface reactions. This may reduce bacterial colonisation of its surface in vivo.

Antibacterial properties of dentin bonding systems, polyacid-modified composite resins and composite resins

This study examined the antibacterial activities of the bonding systems Syntac, EBS and Scotchbond 1, the polyacid-modified composite resins Hytac and Compoglass, and the composite resins Tetric, Z100 and Scalp-it. They were evaluated using the cariogenic bacteria Streptococcus mutans, Lactobacillus salivarius, Streptococcus sorbinus and Actinomyces viscosus in vitro with a modified cylinder drop plate agar diffusion assay. All adhesives of the dentin bonding systems and the polyacid-modified composite resins exhibited various degrees of antibacterial activity against all of the test bacteria. On the contrary, composite resins did not affect bacterial growth. The data suggest that the use of these adhesives and polyacid-modified composite resins may reduce the consequences of microleakage owing to their antibacterial properties.

[The effects of tea polyphenols on the adherence of cariogenic bacterium to the collagen in vitro]

OBJECTIVE

In the first phase of our study, it has been proved that tea polyphenols (TP) can inhibit the preliminary adherence of oral cariogenic bacterium to salivary acquired pellicle. This study is carried on to investigate the effects of tea polyphenols on the preliminary adherence of main cariogenic bacterium to collagen I and reveal the anticarious mechanisms of tea polyphenols further.

METHODS

Tea polyphenols solution was prepared firstly, the concentrations of which were 0.5, 1.0, 2.0 and 4.0 mg/ml. An in-vitro model of experimental pellicle(C-HA) was formed by immerging the hydroxyapatites in 250 micrograms/ml collagen I solution for 1 h. Streptococcus mutans 3a3, Actinomyces viscosus ATCC 19246 and Lactobacillus ATCC 4546 were chosen as the main cariogenic bacterium and radiolabelled by growing them in TPY culture medium supplemented with 3H-thymidine. Two parts of inhibited adherence tests were done with TP-treated C-HA or TP-treated bacterium respectively. In the first one, C-HA was immerged into the TP solution of different concentrations for 1 h before the attachment of bacterium. In the other, the bacterium were mixed with the TP solution for 1 h and then centrifuged and washed before bound to C-HA. KCl buffer solution provided a steady condition to the whole process. Finally, the number of 3H-thymidine-labelled bacterium which attached to C-HA were determined by scintillation counting.

RESULTS

In both the two parts of this study, tea polyphenols solution, the concentrations of which were changed from 1.0 to 4.0 mg/ml could inhibit the attachments of S. mutans 3a3, A. viscosus ATCC 19246 and Lactobacillus ATCC 4546 to C-HA effectively, and the inhibition rates rose with the increase of the concentrations of TP solution. But the inhibitory effects of 0.5 mg/ml TP solution were inconsistent in different tests. The inhibitory functions of tea polyphenols were so prominent that in some experiments, while the concentrations of TP solution were higher than 2.0 mg/ml, the number of 3H-thymidine-labelled bacterium which attached to C-HA was even less than that of the same bacterium which attached to naked HA. These results showed that TP had the remarkable inhibitory efficiency on the attachments of S. mutans, A. viscosus and Lactobacillus to C-HA.

CONCLUSION

Tea polyphenols can inhibit the preliminary adherence of Streptococcus mutans, Actinomyces viscosus and Lactobacillus to C-HA effectively. TP may prevent dentine from caries by decreasing the adherence of main cariogenic bacterium to collagen.

[The effects of tea polyphenols on the adherence of cariogenic bacterium to the salivary acquired pellicle in vitro]

OBJECTIVE

It has been proved that tea polyphenols (TP) can inhibit the sucrose-dependent adherence of oral cariogenic bacterium to the tooth surface. This study is carried on to investigate the effects of tea polyphenols on the preliminary adherence of main cariogenic bacterium to salivary acquired pellicle and reveal the anticarious mechanisms of tea polyphenols further.

METHODS

The hydroxyapatites were coated by saliva to form S-HA, an in-vitro model of experimental pellicle. Streptococcus mutans 3a3 and Actinomyces viscosus ATCC 19246 were chosen as the main cariogenic bacterium, and the microorganisms were radiolabelled by growing them in TPY culture medium supplemented with 3H-thymidine. Tea polyphenols solution was prepared, the concentrations of which were 0.5, 1.0, 2.0 and 4.0 mg/ml respectively. Two parts of inhibited adherence tests were done with TP-treated S-HA or TP-treated bacterium. In the first one, S-HA was immerged into the TP solution of different concentrations for 1 h before the attachment of bacterium. In the other, the bacterium were mixed with the TP solution for 1 h and then centrifuged and washed before bound to S-HA. The whole process was carried on in KCl buffer solution. The number of 3H-thymidine-labelled bacterium which attached to S-HA were determined by scintillation counting.

RESULTS

In both the two parts of this study, tea polyphenols solution, the concentrations of which were changed from 1.0 to 4.0 mg/ml, could decrease the number of S. mutans 3a3 and A. viscosus ATCC 19246, and the inhibition rates rose with the increase of the concentrations of TP solution. But the inhibitory effects of 0.5 mg/ml TP solution were inconsistent in different tests. The results showed that 1.0-4.0 mg/ml TP solution could inhibit the attachments of S. mutans and A. viscosus to S-HA effectively. The inhibitory functions of tea polyphenols were so obvious that in some experiments, while the concentrations of TP solution were changed from 2.0 to 4.0 mg/ml, the number of 3H-thymidine-labelled bacterium which attached to S-HA was even less than that of the same bacterium which attached to naked HA.

CONCLUSION

Tea polyphenols can inhibit the preliminary adherence of Streptococcus mutans and Actinomyces viscosus to S-HA effectively. TP may prevent enamel from caries by decreasing the adherence of main cariogenic bacterium to salivary acquired pellicle.

Photomechanical drug delivery into bacterial biofilms

PURPOSE

To investigate whether photomechanical waves generated by lasers can increase the permeability of a biofilm of the oral pathogen Actinomyces viscosus.

METHODS

Biofilms of Actinomyces viscosus were formed on bovine enamel surfaces. The photomechanical wave was generated by ablation of a target with a Q-switched ruby laser and launched into the biofilm in the presence of 50 microg/ml methylene blue. The penetration depth of methylene blue was measured by confocal scanning laser microscopy. Also, the exposed biofilms were irradiated with light at 666 nm. After illumination, adherent bacteria were scraped and spread over the surfaces of blood agar plates. Survival fractions were calculated by counting bacterial colonies.

RESULTS

Confocal scanning laser microscopy revealed that a single photomechanical wave was sufficient to induce a 75% increase in the penetration depth of methylene blue into the biofilm. This significantly increased the concentration of methylene blue in the biofilm enabling its photodestruction.

CONCLUSIONS

Photomechanical waves provide a potentially powerful tool for drug delivery that might be utilized for treatment of microbial infections.

Addition of antibacterial agents to MMA-TBB dentin bonding systems--influence on tensile bond strength and antibacterial effect

To produce a bonding system which has both high bond strength and antibacterial properties, an antibacterial agent (vancomycin: VCM or metronidazol: MN) was added to the PMMA powder of 4-META/MMA-TBB resin (CB). The influence of the addition of an antibacterial agent on tensile bond strength to dentin and the antibacterial effect were investigated in this study. Forty-seven freshly extracted bovine first or second incisors were used to measure the tensile bond strength to dentin. The bond strengths to bovine dentin were not significantly decreased by addition of VCM (1%, 2%, 5%), or MN (1%) to CB (p < 0.05). The antibacterial effect of CB containing antibacterial agent on six strains of bacteria was investigated by the agar plate diffusion method, analyzing the appearance of the inhibition zone around a resin disk following anaerobic culturing. The resin disks containing VCM showed antibacterial effects on all of the strains examined; the widths of the inhibition zones were 4-15 mm. The resin disks containing MN showed antibacterial effects on three strains; the widths of the inhibition zones were 0-4 mm. It was thus possible to produce a bonding system with both antibacterial effect and high tensile bond strength by addition of VCM to PMMA powder.

In vitro antimicrobial activity of propolis and Arnica montana against oral pathogens

Arnica and propolis have been used for thousands of years in folk medicine for several purposes. They possess several biological activities such as anti-inflammatory, antifungal, antiviral and tissue regenerative, among others. Although the antibacterial activity of propolis has already been demonstrated, very few studies have been done on bacteria of clinical relevance in dentistry. Also, the antimicrobial activity of Arnica has not been extensively investigated. Therefore the aim here was to evaluate in vitro the antimicrobial activity, inhibition of adherence of mutans streptococci and inhibition of formation of water-insoluble glucan by Arnica and propolis extracts. Arnica montana (10%, w/v) and propolis (10%, w/v) extracts from Minas Gerais State were compared with controls. Fifteen microorganisms were used as follows: Candida albicans--NTCC 3736, F72; Staphylococcus aureus--ATCC 25923; Enterococcus faecalis--ATCC 29212; Streptococcus sobrinus 6715; Strep. sanguis--ATCC 10556; Strep. cricetus--HS-6; Strep. mutans--Ingbritt 1600; Strep. mutans--OMZ 175; Actinomyces naeslundii--ATCC 12104, W 1053; Act. viscosus OMZ 105; Porphyromonas gingivalis; Porph. endodontalis and Prevotella denticola (the last three were clinical isolates). Antimicrobial activity was determined by the agar diffusion method and the zones of growth inhibition were measured. To assess cell adherence to a glass surface, the organisms were grown for 18 h at 37 degrees C in test-tubes at a 30 degree angle. To assay water-insoluble glucan formation, a mixture of crude glucosyltransferase and 0.125 M sucrose was incubated for 18 h at 37 degrees C in test-tubes at a 30 degree angle. Arnica and propolis extracts (20 microl) were added to these tubes to evaluate the % of inhibition of cell adherence and water-insoluble glucan formation. The propolis extract significantly inhibited all the microorganisms tested (p < 0.05), showing the largest inhibitory zone for Actinomyces spp. The Arnica extract did not demonstrate significant antimicrobial activity. Cell adherence and water-insoluble glucan formation were almost completely inhibited by the propolis extract at a final concentration of 400 microg/ml and 500 microg/ml, respectively. The Arnica extract showed slight inhibition of the adherence of the growing cells (19% for Strep. mutans and 15% for Strep. sobrinus) and of water-insoluble glucan formation (29%) at these same concentrations. Thus, the propolis extract showed in vitro antibacterial activity, inhibition of cell adherence and inhibition of water-insoluble glucan formation, while the Arnica extract was only slightly active in those three conditions.

Powdered milk micellar casein prevents oral colonization by Streptococcus sobrinus and dental caries in rats: a basis for the caries-protective effect of dairy products

Three animal studies were performed to investigate the influence of the macromolecular structure of milk casein on caries incidence and the possible ecological changes of the oral microbiota by such casein fractions. Towards this end, rats were infected with mixed bacterial suspensions of Streptococcus sobrinus OMZ 176 and Actinomyces viscosus Ny1. Various milk protein fractions were incorporated into carefully balanced powdered cariogenic diets to constitute the sole major protein component. Diets containing micellar casein had a pronounced and highly significant effect on almost all clinical and microbiological parameters examined. Both the formation of advanced dentinal fissure (B) and smooth surface (E) caries lesions was inhibited by diets containing micellar casein; this caries-inhibiting effect appeared to be due mainly to modifications within the plaque microbiota. The proportion of S. sobrinus in the oral cavity of rats was reduced (73-80%) by micellar casein-containing preparations, whereas the A. viscosus population was increased. Both these microbiological parameters were always negatively correlated. This appears to be the first example of a food component other than dietary sugars, selectively modifying the composition of the dental plaque microbiota of rats in such a way as to reduce its pathogenic potential. It also demonstrates the importance of establishing a molecular basis for the role of food components, which prove to be beneficial to oral health.

An in vitro investigation of the antimicrobial activity of an herbal mouthrinse

The purpose of this study was to determine the antimicrobial activity of one prescription and two commercially available over-the-counter mouthrinses and positive and negative controls against bacteria commonly found in the oral cavity. The bacteria used in this study were Streptococcus mutans, Streptococcus sanguis and Actinomyces viscosus. Sterile discs which were treated with the mouthrinses were placed on agar plates along with the controls. Zones of microbial inhibition were measured in millimeters after 48 hours. The results indicated that all of the mouthrinses demonstrated antimicrobial activity against the bacteria tested. Herbal Mouth and Gum Therapy mouthrinse, containing natural ingredients, produced the largest zones of microbial inhibition when compared to Listerine against all three of the bacteria tested. Herbal Mouth and Gum Therapy mouthrinse produced larger zones of microbial inhibition when compared to Peridex against two of the three bacteria tested, and produced similar zones of inhibition against the third bacteria.

Antimicrobial activity of cavity disinfectants

The purpose of this study was to determine the antimicrobial activity of four commercially available cavity disinfectants and one prescription mouthwash as they came into contact with bacteria commonly found in the oral cavity. Streptococcus mutans, salivarius, and Actinomyces viscosus were used in the study. Zones of microbial inhibition were measured in millimeters after 48 hours. The results of this study indicate that all of the antimicrobial agents demonstrated activity against the bacteria tested. Consepsis Solution produced the largest zones of inhibition against all three of the bacteria used.

Bacterial adherence to bleached surfaces of composite resin in vitro

OBJECTIVE

The effect of bleaching agents on bacterial adherence to polished surfaces of composite resin restorations was assessed in vitro.

STUDY DESIGN

Samples of light-curing composite resins were treated with either 10% carbamide peroxide or 10% hydrogen peroxide for 1, 3, or 7 days. Bacterial adherence of Streptococcus mutans, Streptococcus sobrinus, and Actinomyces viscosus to the treated resin samples was analyzed and compared with adherence to nonbleached controls.

RESULTS

A 10% solution of carbamide peroxide caused a significant increase in surface adherence of Streptococcus mutans and Streptococcus sobrinus after 3 days (P < .01). A 10% solution of hydrogen peroxide caused a significant increase in surface adherence of Streptococcus mutans and Streptococcus sobrinus after 3 and 7 days (P < .01). A decrease in adherence of Actinomyces viscosus was found after treatment with 10% hydrogen peroxide for 7 days (P < .05).

CONCLUSIONS

It appears that bleaching agents may affect adherence of certain cariogenic microorganisms to the outer surfaces of composite resin restorations.

Antibacterial activity of proprietary self-etching primers

PURPOSE

To determine and compare the in vitro antibacterial activity of three self-etching primers.

MATERIALS AND METHODS

LB primer (Liner Bond 2), FB primer (Fluoro Bond), and MB conditioner (Tokuso Mac Bond) were evaluated. The antibacterial activity against Streptococcus mutans, Lactobacillus casei, and Actinomyces viscosus was assessed using the agar disc-diffusion method. Twenty microliters of each primer were impregnated into a paper disc and placed on a Brain Heart Infusion agar plate inoculated with a bacterial suspension. The size of inhibition zones produced around the specimens was measured after 48 hours of incubation of the plate. In addition, 20 microliters of each primer was added to a 1 ml suspension of S. mutans adjusted to 1 x 10(6), 1 x 10(5), or 1 x 10(4) CFU/ml in phosphate buffered saline and kept in contact for 30 seconds. The number of viable bacteria after contact with each primer was determined. The results were analyzed by ANOVA and Fisher's PLSD test (P < 0.05).

RESULTS

LB primer and FB primer produced inhibition zones against S. mutans and A. viscosus, and MB conditioner produced an inhibition zone only against A. viscosus. No inhibition zones were produced by any of the primers against L. casei. The three primers completely killed 1 x 10(4) CFU of S. mutans within 30 seconds of contact. When 1 x 10(5) or 1 x 10(6) CFU of bacterial cells were kept in contact, significant differences in the number of recovered viable cells were found among the three primers with MB conditioner being the most bactericidal. LB primer had little bactericidal activity and the mean reduction of viable bacteria by FB primer and MB conditioner was approximately 30% and 65%, respectively.

The effect of herbal extracts in an experimental mouthrinse on established plaque and gingivitis

The purpose of the present study was to establish in vitro the inhibiting effect of a herbal extract mixture on a selected number of micro-organisms and to test in vivo the effect of a mouthwash containing 6.3 mg/ml herbal extract mixture on plaque and gingivitis as compared to a minus active control mouthrinse. The herbal extract was a mixture of: Juniperus communis (juniper), Urtica dioca (nettle), Achillaea millefolium (yarrow); 1:1:1. In the study, in-vitro, the effect of pure herbal extract mixture on acid production of Streptococcus mutans was tested and the minimum inhibitory concentrations (MIC) of the following micro-organisms were tested: Streptococcus mutans, Streptococcus mitis, Actynomyces viscosus, Actynomyces naeslundii, Actinobacillus actinomycetemcomitans, Prevotella intermedia, Campylobacter rectus, Fusobacterium nucleatum, Veillonella parvula. The MIC-values for A. viscosus and P. gingivalis were 100 mg/ml. The MIC-values for A. naeslundii and A. actinomycetemcomitans were considerably lower (10 mg/ml). S. mitis was the most susceptible of the tested organisms to the extract with a MIC value of 1 mg/ml. S. mutans, C. rectus, V. parvula, and F. nucleatum were not influenced by the extracts. No inhibitory effect of the 6.3 mg/ml herbal extract mixture was observed on the acid production of S. mutans. For the study in-vivo, 45 volunteers were selected on the basis of having moderate gingival inflammation. As efficacy parameters the plaque index, modified gingival index and angulated bleeding index were assessed. The subjects were randomly divided among 3 experimental groups (2x test and 1 'minus active' control). The participants were requested to rinse with 10 ml of mouthwash twice a day for a period of three months. After 6 weeks and 3 months, the same clinical indices as at baseline were recorded. The results show no difference between the two test groups and the control group. In conclusion, the results of the present study have shown that the mixture of the 3 herbal extracts, Juniperus communis, Urtica dioca and Achillaea millefolium when used in a mouthrinse has no effect on plaque growth and gingival health.

Antibacterial activity of dentine primer containing MDPB after curing

OBJECTIVES

A monomer methacryloyloxydodecylpyridinium bromide (MDPB) has antibacterial activity before polymerization. Furthermore, the antibacterial agent is immobilized by the polymerization of MDPB and the resin-based material incorporating MDPB is able to show an antibacterial effect even after being cured. The purpose of this study was to investigate the antibacterial effect of a dentine primer containing MDPB after curing.

METHODS

The inhibitory effect of a cured MDPB-containing primer on the growth of Streptococcus mutans, Actinomyces viscosus and Lactobacillus casei was determined by the agar-disc method. The bactericidal activity of cured primer during a 1-h contact period was assessed using S. mutans, and the elution of unpolymerized MDPB was measured with high performance liquid chromatography.

RESULTS

Cured MDPB-containing primer showed an inhibitory effect on the growth of all species which were in contact with the specimen surface, and displayed a little bactericidal effect on S. mutans without releasing any unpolymerized antibacterial components.

CONCLUSION

Incorporation of antibacterial monomer MDPB into dentine primer is beneficial for providing antibacterial activity after curing.