Effects of human milk on adhesion of Streptococcus mutans to saliva-coated hydroxyapatite in vitro

Adhesion of bacteria to pellicle-coated tooth surfaces is the first step in biofilm formation on teeth. The aim of this study was to explore whether human milk prevents or promotes adhesion of cariogenic Streptococcus mutans to saliva-coated hydroxyapatite (HA) using an in vitro model system. S. mutans binding to HA coated with human parotid saliva (s-HA) or human milk was studied, in addition to binding inhibition to s-HA by human milk. S. mutans did not bind to HA coated with milk. S. mutans binding to s-HA was inhibited by milk from 15 (71 %) of 21 women, whereas milk from the remaining 6 mothers enhanced binding of S. mutans to s-HA. Inhibition of S. mutans binding correlated with bacterial binding to s-HA (r = 0.76). Human milk does not mediate adhesion of S. mutans to HA in vitro, but affects adhesion in an individually varying fashion. Phenotypic variations in milk and saliva glycosylation may explain the inhibitory capacity and possibly affect susceptibility to colonization by S. mutans in childhood.     

Inhibitory effects of oolong tea extract on caries-inducing properties of mutans streptococci.

The inhibitory effects of oolong tea extract (OTE) on the caries-inducing properties of mutans streptococci were examined in vitro. OTE reduced the rate of acid production by mutans streptococci accompanied with the retardation of growth rate of mutans streptococci, while the action by chromatographically isolated oolong tea polyphenol (OTF6) was weak. On the other hand, both oolong tea products decreased cell surface hydrophobicity of almost all the oral streptococci examined in the present study, and also induced cellular aggregation of Streptococcus mutans, Streptococcus oralis, Streptococcus sanguis or Streptococcus gordonii. In these reactions, OTF6 showed a more pronounced activity than OTE. Furthermore, the oolong tea products inhibited the adherence of mutans streptococci to saliva-coated hydroxyapatite. These results suggest that OTF6 may inhibit bacterial adherence to the tooth surfaces by reducing the hydrophobicity of mutans streptococci, and OTE may inhibit caries-inducing activity of mutans streptococci by reducing the rate of acid production.     

Influence of cranberry juice on glucan-mediated processes involved in Streptococcus mutans biofilm development

Cranberry juice (CJ) has biological properties that may provide health benefits. In this study, we investigated the influence of CJ (pH 5.5) on several activities in vitro associated with the development of Streptococcus mutans UA159 biofilms. The ability of CJ to influence the adherence of S. mutans to either saliva- (sHA) or glucan-coated hydroxyapatite (gsHA), and to inhibit the glucan production by purified glucosyltransferases adsorbed to sHA was determined. For the adherence assays, we used both uncoated and saliva-coated bacterial cells. Furthermore, we examined whether CJ interferes with the viability, development, polysaccharide composition and acidogenicity of S. mutans biofilms. A solution containing equivalent amounts of glucose, fructose and organic acids at pH 5.5 was used as negative control. The adherence of S. mutans (uncoated and saliva-coated) to either sHA or gsHA treated with 25% CJ (v/v) was remarkably reduced (40-85% inhibition compared to control: p < 0.05), indicating that CJ effectively blocked the bacterial adherence to binding sites in salivary pellicle and in glucans. In contrast, when the bacterial cells alone were treated with CJ they adhered to the similar untreated surfaces. Cranberry juice (25%, v/v) also inhibited the activities of surface-adsorbed GTF B and C (70-80% inhibition compared to control, p < 0.05). The effect of CJ on the viability of microorganisms in biofilms was not significant. Biofilm formation and accumulation were significantly reduced by topical applications of 25% CJ (v/v) twice daily with 1-min exposures (p < 0.05). The biomass and insoluble glucan content of the biofilms in addition to its acidogenicity were significantly reduced by cranberry treatments (p < 0.05). Our data show that cranberry juice inhibited glucan-mediated biofilm development and acid production, and holds promise as a natural product to prevent biofilm-related oral diseases.     

黄芩苷对变异链球菌UA159体外的抑制作用

目的 探讨黄芩苷对变异链球菌国际标准株UA159的体外抑制作用.方法 采用液体倍比稀释法结合酶标仪测OD600值测定黄芩苷对变异链球菌UA159的最低抑菌浓度(minimum inhibitory concentration,MIC).利用酶标仪测定不同浓度的黄芩苷药液中变异链球菌UA159的OD600值,绘制生长曲线...     

Role of gene E2f1 in susceptibility to bacterial adherence of oral streptococci to tooth surfaces in mice

Dental plaque is composed of a biofilm community of microorganisms on teeth that coats the oral cavity, including attaching to the teeth, and provides a protective reservoir for oral microbial pathogens, which are the primary cause of persistent and chronic infectious diseases. Oral streptococci are pioneering organisms that play an important role in biofilm formation on tooth surfaces as well as being primary causative agents of dental caries. The purpose of this study was to clarify the role of the E2f1 gene in susceptibility to dry mouth and bacterial adherence of oral streptococci to tooth surfaces in animal model experiments. A mutation of the E2f1 gene in mice is known to cause enhanced T-lymphocyte proliferation, leading to testicular atrophy, splenomegaly, salivary gland dysplasia, and other systemic and organ-specific autoimmunity. We found a decreased volume of saliva production and protein production rate, along with increased amylase activity, IgA concentration, and mucin 1 concentration in E2F-1(-/-) mice as compared with the control C57BL/6 mice. Further, we quantified the recolonization of oral streptococci in E2F-1(-/-) mice and found that a higher number of some oral streptococci were colonized on the teeth of these mice. In particular, following oral ingestion of 1% sucrose in water, the colonization of Streptococcus mutans increased in comparison with other streptococci. Our results suggest that the E2f1 gene may affect susceptibility for oral biofilm formation by streptococci in humans with dry mouth.     

Synergistic effects of streptococcal glucosyltransferases on adhesive biofilm formation

Glucosyltransferases (GTF)-I and GTF-SI of Streptococcus mutans synthesize water-insoluble and both water-soluble and -insoluble glucans, respectively, and play essential roles in the sucrose-dependent adhesion of the organism to tooth surfaces. To examine the interactions of different GTFs on artificial biofilm formed by S. mutans and other oral streptococci, we generated GTF-I- and GTF-SI-hyperproducing isogenic mutant strains. Transformant B42-21, which hyperexpressed GTF-SI, exhibited firm adhesion in the presence of sucrose, whereas transformant B42-10, which hyperexpressed GTF-I, failed to exhibit firm adhesion. Furthermore, co-culture of transformant B42-21 with water-soluble glucan-synthesizing Streptococcus sanguinis yielded firm adhesion, while the addition of dextran T10 to B42-21 growing culture had no effect on adhesion. These findings suggest that GTF-SI has a strong effect on sucrose-dependent adhesion and is essential for biofilm formation on smooth surfaces, in cooperation with water-soluble glucans synthesized de novo by oral streptococci that inherently lack cell adhesion ability.     

Effects of oral streptococci on biofilm formation by cariogenic bacteria in dual species cultures

The effects of oral commensal streptococci (Streptococcus sanguinis, Streptococcus gordonii, Streptococcus mitis, and Streptococcus salivarius) on biofilm formation by cariogenic mutans streptococci (Streptococcus mutans and Streptococcus sobrinus) were investigated. Cell suspensions were cultured on 96-well microtiter plates coated with or without salivary components (SC), and in flow cell systems coated with SC in tryptic soy broth including 0.25% sucrose without dextrose (TSB). The resultant biofilm formations were stained using safranin or a LIVE/DEAD BacLight Viability Kit, and examined with absorbance at 492 nm or using confocal laser scanning microscopy. Mutans streptococci and S. sanguinis biofilms were formed significantly on the polystyrene surfaces in TSB. Further, in combination cultures, S. sanguinis formed a sufficient biofilm when cultured with S. mutans. However, when S. sanguinis was cultured with S. sobrinus, biofilm formation was slightly inhibited. S. gordonii also inhibited biofilm formation in the culture with S. sobrinus, but not when cultured with S. mutans. S. mitis and S. salivarius collapsed the biofilm morphology and inhibited volume development in some conditions when cultured with S. mutans or S. sobrinus. Biofilm formation by mutans streptococci was challenged and collapsed on the whole by culturing with each of the other oral streptococci. These results indicate that co-culturing of multiple species of mutans streptococci and other oral streptococci has physical effects related to previous attachment and colonization on the surface, as well as biological effects to regulate biofilm formation.     

Effect of tissue fluids on hydrophobicity and adherence of Enterococcus faecalis to dentin

This in vitro study was carried out to determine (1) the hydrophobicity of selected oral bacteria, (2) the influence of growth media (saliva and serum) and mode of growth (planktonic or biofilm) on the hydrophobicity of Enterococcus faecalis, and (3) the influence of growth media and conditioning fluids on the adherence of E. faecalis to dentin. The ability to bind to a hydrocarbon phase (xylene) was used as an index of relative hydrophobicity of cells. Fluorescent microscopy-based technique was used to assay the bacterial adherence to dentin. Results showed that bacteria involved in the primary stage of oral biofilm formation such as Streptococcus mutans, Fusobacterium nucleatum, and Porphyromonas gingivalis are relatively more hydrophobic than E. faecalis. The hydrophobicity of E. faecalis was significantly increased during starvation and biofilm mode of growth (p < .05). The adherence of E. faecalis to dentin was appreciably increased after starvation and when dentin was conditioned with saliva. It was observed that surface conditioning of dentin with saliva and starvation can enhance the adherence of E. faecalis to dentin. The findings from this study indicated that the coronal leakage of saliva and the physiologic state of microbes might play an important role in the adherence and biofilm formation of bacteria to root canal dentin.     

Novel protein-repellent dental adhesive containing 2-methacryloyloxyethyl phosphorylcholine

Objectives

Biofilms at tooth-restoration margins can produce acids and cause secondary caries. A protein-repellent adhesive resin can potentially inhibit bacteria attachment and biofilm growth. However, there has been no report on protein-repellent dental resins. The objectives of this study were to develop a protein-repellent bonding agent incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC), and to investigate its resistance to protein adsorption and biofilm growth for the first time.

Methods

MPC was incorporated into Scotchbond Multi-Purpose (SBMP) at 0%, 3.75%, 7.5%, 11.25%, and 15% by mass. Extracted human teeth were used to measure dentine shear bond strengths. Protein adsorption onto resins was determined by a micro bicinchoninic acid (BCA) method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to measure biofilm metabolic activity and colony-forming unit (CFU) counts.

Results

Adding 7.5% MPC into primer and adhesive did not decrease the dentine bond strength, compared to control (p > 0.1). Incorporation of 7.5% of MPC achieved the lowest protein adsorption, which was 20-fold less than that of control. Incorporation of 7.5% of MPC greatly reduced bacterial adhesion, yielding biofilm total microorganism, total streptococci, and mutans streptococci CFU that were an order of magnitude less than control.

Conclusions

A protein-repellent dental adhesive resin was developed for the first time. Incorporation of MPC into primer and adhesive at 7.5% by mass greatly reduced the protein adsorption and bacterial adhesion, without compromising the dentine bond strength.

Clinical significance

The novel protein-repellent primer and adhesive are promising to inhibit biofilm formation and acid production, to protect the tooth-restoration margins and prevent secondary caries.     

Effect of Magnolia Officinalis Extract on Cariogenic Activity of Mutans Streptococci

目的：从中药厚朴中提取抗变链活性成分,并研究其对变形链球菌致龋特性的影响。方法：本研究应用薄层层析,萃取分离,硅胶色谱柱层析等现代中药化学实验方法,从生药厚朴中提取出有效成分MO2,用微量液体稀释法检测不同血清型变形链球菌对MO2的敏感性。以S.mutans MT703和S.sobrinus B13为实验菌株,分析MO2对其细胞表面疏水能力和合成水不溶性葡聚糖能力的影响。结果：MO2能降低细胞表面疏水率,抑制葡糖基转移酶催化合成水不溶性葡聚糖。随着MO2浓度的升高,细胞表面疏水率下降;80μg/ml的MO2对S.mutansMT703合成水不溶性葡聚糖的抑制率为45.4%,对S.sobrinusB13合成水不溶性葡聚糖的抑制率达43.5%。结论：厚朴提取物MO2对变形链球菌致龋能力有较强抑制作用。     

Effects of amine fluoride on biofilm growth and salivary pellicles

The amine fluoride (AmF) N'-octadecyl-trimethylene-diamine-N,N,N'-tris(2-ethanol)-dihydro-fluoride is a cationic antimicrobial which can have beneficial effects on plaque formation. Here, we determine changes in pellicle and bacterial cell surface properties of the strains Actinomyces naeslundii HM1, Streptococcus mutans NS, S.mutans ATCC 700610, S. sobrinus HG1025 and S. oralis HM1 upon adsorption of this AmF and accompanying effects on bacterial adhesion and biofilm growth. In vitro pellicles had a zeta potential of -12 mV that became less negative upon adsorption of AmF. The chemical functionalities in which carbon and oxygen were involved changed after AmF adsorption and AmF-treated pellicles had a greater surface roughness than untreated pellicles. Water contact angles in vitro decreased from 56 to 45 degrees upon AmF treatment, which corresponded with water contact angles (44 degrees ) measured intraorally on the front incisors of volunteers immediately after using an AmF-containing toothpaste. All bacterial strains were negatively charged and their isoelectric points (IEP) increased upon AmF adsorption. Minimal inhibitory concentrations were smallest for strains exhibiting the largest increase in IEP. Adhesion to salivary pellicles and biofilm growth of the mutans streptococcal strains were significantly reduced after AmF treatment, but not of A. naeslundii or S. oralis. However, regardless of the strain involved, biofilm viability decreased significantly after AmF treatment. The electrostatic interaction between cationic AmF and negatively charged bacterial cell surfaces is pivotal in establishing reduced biofilm formation by AmF through a combination of effects on initial adhesion and killing. The major effect of AmF treatment, however, was a reduction brought about in biofilm viability.     

Biofilm formation of Candida albicans is variably affected by saliva and dietary sugars

The pathogenesis of both superficial and systemic candidiasis is closely dictated by properties of the yeast biofilms. Despite extensive investigations on bacterial biofilms, the characteristics of candidal biofilms, and various factors affecting this process remain to be determined. Therefore we examined the effect of human whole saliva and dietary sugars, glucose and galactose on the adhesion and biofilm formation of Candida albicans. Biofilms of C. albicans isolate 192 887 g were developed on polystyrene, flat-bottomed 96-well microtiter plates and monitored using ATP bioluminescence and tetrazolium (XTT) reduction assays as well as the conventional colony forming unit (CFU) evaluation. Our data showed that both the ATP and the XTT assays strongly correlated with the CFU assay (ATP versus CFU: r = 0.994, P = 0.006; XTT versus CFU: r = 0.985, P = 0.015). Compared with a glucose-supplemented (100 mM) medium, galactose containing (500 mM) medium generated consistently lower levels of both candidal adhesion and biofilm formation (all P < 0.05), but a higher pace of biofilm development over time (96 h). Whist the presence of an immobilised saliva coating had little effect on either the candidal adhesion or biofilm formation, the addition of saliva to the incubation medium quantitatively affected biofilm formation especially on day 3 and 4, without any significant effect on yeast adhesion. To conclude, biofilm formation of C. albicans within the oral milieu appears to be modulated to varying extents by dietary and salivary factors and, further investigations are required to elucidate these complex interactions.     

口腔中过氧化氢的来源及在微生态平衡中的作用

过氧化氢（H₂O₂）作为口腔中一种重要的抑菌物质,在口腔微生态平衡中发挥着重要作用。在口腔龈上菌斑定植的先锋菌中,约有80%细菌属于口腔链球菌属,这些口腔链球菌可以利用不同的氧化酶合成H₂O₂,同时H₂O₂可通过抑制对H₂O₂敏感的微生物参与菌间竞争拮抗,使氧耐受菌得以存活,从而调节生物膜的发展过程;H₂O₂还可通过影响微生物细胞外DNA的释放和感受态细胞的形成进而影响基因的水平转移,调节生物膜对口腔环境的适应能力;同时口腔微生物也可通过一系列机制耐受H₂O₂。此外,H₂O₂在微生物与宿主的关系中也发挥着重要作用。本文就口腔中H₂O₂的来源及其在口腔微生态平衡的作用两方面的研究进展进行综述。     

MPC-polymer reduces adherence and biofilm formation by oral bacteria

Oral biofilms such as dental plaque cause dental caries and periodontitis, as well as aspiration pneumonia and infectious endocarditis by translocation. Hence, the suppression of oral biofilm formation is an issue of considerable importance. Mechanical removal, disinfectants, inhibition of polysaccharide formation, and artificial sugar have been used for the reduction of oral biofilm. From the viewpoint of the inhibition of bacterial adherence, we investigated whether aqueous biocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymer can reduce streptococcal colonization and biofilm formation. We examined the effects of MPC-polymer on streptococcal adherence to saliva-coated hydroxyapatite and oral epithelial cells, and the adherence of Fusobacterium nucleatum to streptococcal biofilm. MPC-polymer application markedly inhibited both the adherence and biofilm formation of Streptococcus mutans on saliva-coated hydroxyapatite and streptococcal adherence to oral epithelial cells, and reduced the adherence of F. nucleatum to streptococcal biofilms. A small-scale clinical trial revealed that mouthrinsing with MPC-polymer inhibited the increase of oral bacterial numbers, especially of S. mutans. These findings suggest that MPC-polymer is a potent inhibitor of bacterial adherence and biofilm development, and may be useful to prevent dental-plaque-related diseases. (UMIN Clinical Trial Registry UMIN000003471).     

Biofilm-specific surface properties and protein expression in oral Streptococcus sanguis

OBJECTIVE: Oral streptococci are primary colonisers of the tooth surface and are abundant in dental plaque biofilms. Bacteria growing in these relatively dense, surface-associated communities are phenotypically quite distinct from their planktonic counterparts. The purpose of the present study was to develop a method to investigate biofilm-specific surface protein expression by Streptococcus sanguis to help provide a better understanding of the critical events in plaque development. DESIGN: Biofilm cells were grown on the surface of glass beads in a biofilm device fed with mucin-containing artificial saliva. Planktonic cells were grown in continuous culture at approximately the same growth rate. Surface hydrophobicity of biofilm and planktonic cells was determined by hexadecane partitioning, and expression of streptococcal fibronectin adhesin CshA was determined in ELISA using specific antiserum. Antisera raised to glutaraldehyde-fixed whole biofilm or planktonic grown cells were used to screen an expression library of S. sanguis genomic DNA, and isolated clones were sequenced. RESULTS: Phenotypic analysis of biofilm and planktonic cells confirmed that mode of growth affected surface properties of S. sanguis. Thus, hydrophobicity and CshA expression was significantly elevated in biofilm cells. Library screening with biofilm antiserum yielded 32 recombinant clones representing 21 different S. sanguis proteins involved in adhesion and colonisation, carbohydrate utilisation or bacterial metabolism. In differential analysis of four selected Escherichia coli clones, biofilm antiserum reacted five times stronger than planktonic antiserum with cell-free extracts of clones encoding homologues of CshA and Cna collagen adhesin of Staphylococcus aureus, suggesting that these surface proteins are up-regulated in biofilm cells. In contrast, both antisera reacted equally strongly with cell-free extracts of the remaining two clones (encoding dihydrofolate synthase and an unknown protein). CONCLUSIONS: The method described represents a useful means for determining bacterial protein expression in biofilms based on a combination of molecular and immunological techniques. Surface expression of putative fibronectin and collagen adhesins was up-regulated in biofilm cells.     

中药对口腔细菌生物膜作用的实验研究

目的用五倍子和蜂房的有效成分作为实验药物研究中药对口腔细菌生物膜结构、活性的影响及对生物膜中葡萄糖转移酶（GTF）活性的影响，探讨中药防龋的可能性。方法用荧光显微镜结合特异荧光染料标记口腔细菌生物膜中死菌和活菌的方法，研究实验药物对口腔细菌生物膜结构和活性的影响。硫酸铵沉淀法提取粗酶，Neson-Somogyi法测定还原糖，G250微量蛋白定量GTF还原糖计算GTF活性单位，评价实验药物对口腔细菌生物膜中GTF活性的影响。结果早期细菌定植黏附到形成成熟生物膜结构的过程中都存在一定数量的死菌。24h常态生物膜结构中活菌面积占主导地位，有少量死菌存在，细菌互相紧密黏附在一起，生物膜结构清晰。0．05％氯己定对24h细菌生物膜作用后，细菌总量明显下降，残存滞留的细菌基本为死菌。0．023％的NaF作用于细菌生物膜后，生物膜结构发生明显变化，细菌总量明显减少，存在的细菌以活菌为主。经4g／L五倍子多酚性化合物（GCE）、五倍子化学组分B（GCE-B）及32g／L蜂房化学组分1（NVE1）作用后，生物膜结构模糊不清，细菌散开，生物膜结构密度下降，其中死菌和活菌量基本相同。生物膜细菌总量减少，与24h常态生物膜相比，差异有统计学意义（P〈0．05）。各实验组活菌百分比与阴性对照组活菌百分比相比差异有统计学意义（P〈0．05）。24h口腔细菌生物膜经4g／L GCE以及32异／L NVE1作用后，GTF的活性受到明显抑制，与阴性对照组相比差异均有统计学意义（P〈0．05）。GCE-B在实验浓度下对GTF的活性未产生明显的抑制作用。结论五倍子和蜂房有效成分组成的实验药物对口腔细菌生物膜的抑制作用不单纯是对口腔生物膜细菌有杀灭作用，还可能通过对口腔细菌生物膜结构的改变调整其内部的细菌组成及抑制细菌生物膜中GTF活性而发挥作用。     

In vitro modulation of oral bacterial adhesion to saliva-coated hydroxyapatite beads by milk casein derivatives

Bovine caseinate, derivatives of its glycosylated moiety [caseinoglycomacropeptide (CGP)], and caseinophosphopeptides were evaluated as inhibitors of adhesion of oral bacteria to saliva-coated hydroxyapatite beads (S-HA). All milk casein-derived components behaved as potent inhibitors of Streptococcus sanguis OMZ 9 and Streptococcus sobrinus OMZ 176 adhesion to S-HA, whereas neither bovine serum albumin nor polyethyleneglycol were able to interfere with the adhesion of these strains. By contrast, none of the molecular species tested was able to inhibit the attachment of Actinomyces viscosus Ny 1 to S-HA. On the other hand, casein derivatives were shown to displace human serum albumin from S-HA beads. They were also able to bind to the bacterial cell surface of all strains examined. Collectively, these findings suggest that interactions between acidic casein-derived milk components and the biological surfaces involved in bacterial adhesion to S-HA result in an inhibitory effect that is selective for the oral streptococci examined.     

Effect of Weissella cibaria isolates on the formation of Streptococcus mutans biofilm

The objective of this study was to isolate and identify lactic acid bacteria able to inhibit the in vitro formation of Streptococcus mutans biofilm as well as the in vivo formation of oral biofilm. Two strains, CMS1 and CMS3, exhibiting profound inhibitory effects on the formation of S. mutans biofilm and the proliferation of S. mutans, were isolated from children's saliva and identified as Weissella cibaria by 16S rDNA sequencing. The water-soluble polymers produced from sucrose by the W. cibaria isolates also inhibited the formation of S. mutans biofilm. According to the results of thin-layer chromatographic analysis, the hydrolysates of water-soluble polymers produced by the isolates were identical to those of dextran, forming mostly alpha-(1-6) glucose linkages. In the clinical study, the subjects mouthrinsed with a solution containing W. cibaria CMS1 evidenced plaque index reduction of approximately 20.7% (p < 0.001). These results indicate that the W. cibaria isolates possess the ability to inhibit biofilm formation, both in vitro and in vivo.     

Polyphenolic beverages reduce initial bacterial adherence to enamel in situ

Objectives

Polyphenols are antibacterial and anti-oxidative natural agents. The present in situ study aimed to investigate the effect of different polyphenolic beverages on initial bacterial adherence to enamel in the oral cavity.

Methods

Initial biofilm formation was performed on bovine enamel specimens mounted buccally on individual upper jaw splints and carried by six subjects. After 1 min of pellicle formation, oral rinses with black tea, green tea, grape juice, Cistus tea or red wine were performed for 10 min. Afterwards the slabs were carried for another 19 or 109 min, respectively. Samples exposed to the oral fluids for 30 and 120 min served as controls. Following intraoral exposure, the slabs were rinsed with saline solution. The amount of adherent bacteria was determined with DAPI-staining (4′,6-diamidino-2-phenylindole) and with fluorescence-in situ hybridization (FISH) of eubacteria and streptococci.

Results

Rinses with all beverages reduced the amount of detectable bacteria. Lowest number of adherent bacteria was found following rinses with red wine, Cistus tea and black tea as measured with DAPI (up to 66% reduction of adherent bacteria vs. controls). Also FISH revealed significant impact of most tested beverages.

Conclusions

Rinses with certain polyphenolic beverages as well as consumption of these foodstuffs may contribute to prevention of biofilm induced diseases in the oral cavity.     

Susceptibility of planktonic versus attached<Emphasis Type="Italic"> Streptococcus sanguinis</Emphasis> cells to chlorhexidine

The effect of chlorhexidine (CHX) on the viability of Streptococcus sanguinis was investigated in a preclinical biofilm model separately on cells in the planktonic or attached life form. Saliva-coated human enamel and glass slides were exposed to the streptococci suspended in sterile saliva for 30 min and 60 min in the flow chamber system. The CHX exposition was performed in two parts: pretreatment of the planktonic bacteria before their attachment to enamel or glass, and treatment of bacteria already attached to enamel. The susceptibility measured by vitality percentages was determined by fluorescence microscopy using vital/dead cells. After CHX pretreatment of planktonic cells, the mean values of the vitality percentages after adhesion were 14-18% (enamel) and 24-25% (glass). In contrast, the mean vitality percentages of untreated attached streptococci reached 70-75% (enamel) and 68% (glass). The vitality percentages of CHX-exposed bacteria dropped markedly to 2-5%, whereas those of untreated attached cells remained at 65-66%. The exposure of initially attached streptococci to CHX resulted in greater reduction of bacterial viability than with the planktonic counterparts. This preclinical biofilm model allows the investigation of various bacterial life forms and can furthermore be used to select efficient antiplaque therapeutics which might be beneficial for clinical plaque control.