Adhesion Of Mutans Research Articles

Examination of Streptococcus Mutans Adhesion in Current Hybrid Ceramics and Composites

This study evaluated the surface topography and bacterial adhesion of a different hybrid ceramics and resin composites after optimal surface finishes. A total of disk samples were prepared using two different CAD/CAM blocks [Vita Enamic (VE), Shofu HC (SHC)] and two different composites [Tetric N Ceram bulk-fill (TNC), Estelite Sigma Quick (ESQ)] with diameter 10 mm and thickness 4.0 ± 0.2mm. Fifteen disc samples were produced for each group (n=15). Surfaces of the sample disks were polished according to the manufacturer’s recommendations with the specially produced polish sets. The surface roughness of specimens was analyzed parameter (Ra), sterilized, and subjected to bacterial adhesion. Data were submitted to one-way ANOVA and Tukey’s test (α= 0.05). TNC and ESQ groups had lower surface roughness than VE and SHC groups (p<0.05). There was no difference in bacterial adhesion between hybrid CAD/CAM blocks and composite materials. The material type and surface finishing system did not significantly interfere with surface roughness parameters and bacterial adhesion. The surface polishing of nanocomposite resins performed is better than hybrid ceramic after polishing. An adequate finishing/polishing technique should always be applied after any adjustments made to indirect restorations with these materials tested. There is no difference between bacterial adhesions of the tested materials. If appropriate and sufficient, polishing is performed.

Improvement in the Microbial Resistance of Resin-Based Dental Sealant by Sulfobetaine Methacrylate Incorporation.

Prevention of dental caries is a key research area, and improvement of the pit and fissure sealants used for caries prevention has been of particular interest. This report describes results of incorporating a zwitterion, sulfobetaine methacrylate (SB), into photo-polymerized resin-based sealants to enhance resistance to cariogenic bacteria and protein adhesion. Varying amounts (1.5–5 wt%) of SB were incorporated into a resin-based sealant, and the flexural strength, wettability, depth of cure, protein adhesion, bacterial viability, and cell cytotoxicity of the resultant sealants were evaluated. The flexural strength decreased with the increasing SB content, but this decrease was statistically significant only for sealants containing ≥3 wt% SB. Incorporating a zwitterion led to a significant reduction in the water contact angle and protein adhesion. The colony-forming unit count showed a significant reduction in the bacterial viability of S. mutans, which was confirmed with microscopic imaging. Moreover, cell cytotoxicity analysis of SB-modified sealants using an L929 fibroblast showed a cytotoxicity comparable to that of an unmodified control, suggesting no adverse effects on the cellular metabolism upon SB introduction. Hence, we conclude that the addition of 1.5–3 wt% SB can significantly enhance the inherent ability of sealants to resist S. mutans adhesion and prevent dental caries.

Epigallocatechin-3-Gallate/Nanohydroxyapatite Platform Delivery Approach to Adhesive-Dentin Interface

Interface science is an intrinsic component of dental bonding. Current adhesive techniques allow clinicians to bond resin composites to dentin for the restoration of a defected tooth. However, a vulnerable adhesive-dentin interface remains clinically challenging by far resulting in frequent replacement of the restorations. The inappropriate management of exposed dentin plays a major role in jeopardizing the stability of the adhesive-dentin interface, leading to subsequent restorative failure. To overcome this problem, this paper highlights epigallocatechin-3-gallate/nanohydroxyapatite (EGCG/nHAp) platform (mesoporous silica-based) delivery approach to the adhesive-dentin interface and investigates its effectiveness on dentin bonding. Microtensile bond strength, interfacial nanoleakage, in situ zymography, and Streptococcus mutans biofilm formation were assessed. Results revealed that applying the EGCG/nHAp delivery platform on exposed dentin could preserve the dentin bond strength and reduce interfacial nanoleakage after collagenase ageing; moreover, it could inactivate the activity of matrix metalloproteinase within the hybrid layer and inhibit the adhesion and biofilm formation of Streptococcus mutans. The proposed approach demonstrates great potential for stabilizing the adhesive-dentin interface, which may aid in achieving a durable dentin bonding efficiency and preventing secondary caries progression, thereby indicating a promising strategy to prolong the service life of dental restorations.

Streptococcus mutans adhesion force sensing in multi-species oral biofilms

Bacteria utilize chemical and mechanical mechanisms to sense their environment, to survive hostile conditions. In mechanical sensing, intra-bilayer pressure profiles change due to deformation induced by the adhesion forces bacteria experience on a surface. Emergent properties in mono-species Streptococcus mutans biofilms, such as extracellular matrix production, depend on the adhesion forces that streptococci sense. Here we determined whether and how salivary-conditioning film (SCF) adsorption and the multi-species nature of oral biofilm influence adhesion force sensing and associated gene expression by S. mutans. Hereto, Streptococcus oralis, Actinomyces naeslundii, and S. mutans were grown together on different surfaces in the absence and presence of an adsorbed SCF. Atomic force microscopy and RT-qPCR were used to measure S. mutans adhesion forces and gene expressions. Upon SCF adsorption, stationary adhesion forces decreased on a hydrophobic and increased on a hydrophilic surface to around 8 nN. Optical coherence tomography showed that triple-species biofilms on SCF-coated surfaces with dead S. oralis adhered weakly and often detached as a contiguous sheet. Concurrently, S. mutans displayed no differential adhesion force sensing on SCF-coated surfaces in the triple-species biofilms with dead S. oralis, but once live S. oralis were present S. mutans adhesion force sensing and gene expression ranked similar as on surfaces in the absence of an adsorbed SCF. Concluding, live S. oralis may enzymatically degrade SCF components to facilitate direct contact of biofilm inhabitants with surfaces and allow S. mutans adhesion force sensing of underlying surfaces to define its appropriate adaptive response. This represents a new function of initial colonizers in multi-species oral biofilms.

Evaluation of titanium dioxide coating on surface roughness of nickel-titanium archwires and its influence on Streptococcus mutans adhesion and enamel mineralization: A prospective clinical study

This research aimed to evaluate the effect of titanium dioxide (TiO2) coating on surface roughness (Ra) of nickel-titanium (NiTi) archwires and its influence on Streptococcus mutans (S mutans) adhesion and enamel mineralization at the end of 1month in orthodontic patients and to evaluate the integrity of the TiO2 coating. Twelve patients undergoing orthodontic treatment with preadjusted edgewise appliance formed the sample for this prospective clinical study. Uncoated NiTi archwires and TiO2 nanoparticle coated NiTi archwires in as-received condition and after 1month of intraoral use were subjected to Ra analysis using surface profilometry, and surface topography using scanning electron microscopy. S mutans adhesion was evaluated on the retrieved archwires using real-time polymerase chain reaction (PCR). Enamel mineral content in the arches related to the uncoated and coated archwires was evaluated using DIAGNOdent. After 1month of intraoral use, both coated and uncoated archwires exhibited a rougher surface with coated archwires demonstrating greater quantum of increase (control, P=0.002; experimental, P=0.002). S mutans adhesion was more in uncoated archwires (P=0.0005). The TiO2 nanoparticle coating on the NiTi archwires showed delamination, deterioration and was lost by 60% at the end of 1month. Laser fluorescence values did not show any significant difference (control, P=0.182; experimental, P=0.105). TiO2 nanoparticle coating on NiTi archwires causes an initial reduction in roughness; however, at the end of 1month, the benefit was lost. S mutans adhesion was lesser on the coated wires, which could be attributed to reduced initial Ra and antibacterial property of TiO2. Orthodontic archwire appears to have a limited role in enamel demineralization.

Casein phosphopeptide combined with fluoride enhances the inhibitory effect on initial adhesion of Streptococcus mutans to the saliva-coated hydroxyapatite disc

BackgroundRecent preventive strategies for dental caries focus on targeting the mechanisms underlying biofilm formation, including the inhibition of bacterial adhesion. A promising approach to prevent bacterial adhesion is to modify the composition of acquired salivary pellicle. This in vitro study investigated the effect and possible underlying mechanism of pellicle modification by casein phosphopeptide (CPP) on Streptococcus mutans (S. mutans) initial adhesion, and the impact of fluoride on the efficacy of CPP.MethodsThe salivary pellicle-coated hydroxyapatite (s-HA) discs were treated with phosphate buffered saline (negative control), heat-inactivated 2.5% CPP (heat-inactivated CPP), 2.5% CPP (CPP) or 2.5% CPP supplemented with 900 ppm fluoride (CPP + F). After cultivation of S. mutans for 30 min and 2 h, the adherent bacteria were visualized by scanning electron microscopy (SEM) and quantitatively evaluated using the plate count method. Confocal laser scanning microscopy (CLSM) was used to evaluate the proportions of total and dead S. mutans. The concentrations of total, free, and bound calcium and fluoride in the CPP and fluoride-doped CPP solutions were determined. The water contact angle and zeta potential of s-HA with and without modification were measured. The data were statistically analyzed using one-way ANOVA followed by a Turkey post hoc multiple comparison test.ResultsCompared to the negative control group, the amount of adherent S. mutans significantly reduced in the CPP and CPP + F groups, and was lowest in the CPP + F group. CLSM analysis showed that there was no statistically significant difference in the proportion of dead S. mutans between the four groups. Water contact angle and zeta potential of s-HA surface significantly decreased in the CPP and CPP + F groups as compared to the negative control group, and both were lowest in the CPP + F group.ConclusionsPellicle modification by CPP inhibited S. mutans initial adhesion to s-HA, possibly by reducing hydrophobicity and negative charge of the s-HA surface, and incorporating fluoride into CPP further enhanced the anti-adhesion effect.

Influence of 2'-fucosyllactose and galacto-oligosaccharides on the growth and adhesion of Streptococcus mutans.

Human milk oligosaccharides, such as 2'-fucosyllactose (2'-FL), and galacto-oligosaccharides (GOS), a prebiotic carbohydrate mixture, are being increasingly added to infant formulas, necessitating the understanding of their impact on the oral microbiota. Here, for the first time, the effects of 2'-FL and GOS on the planktonic growth and adhesion characteristics of the caries-associated oral pathogen Streptococcus mutans were assessed, and the results were compared against the effects of xylitol, lactose and glucose. There were differences in S. mutans growth between 2'-FL and GOS. None of the three S. mutans strains grew with 2'-FL, while they all grew with GOS as well as lactose and glucose. Xylitol inhibited S. mutans growth. The adhesion of S. mutans CI 2366 to saliva-coated hydroxyapatite was reduced by 2'-FL and GOS. Exopolysaccharide-mediated adhesion of S. mutans DSM 20523 to a glass surface was decreased with 2'-FL, GOS and lactose, and the adhesion of strain CI 2366 strain was reduced only by GOS. Unlike GOS, 2'-FL did not support the growth of any S. mutans strain. Neither 2'-FL nor GOS enhanced the adhesive properties of the S. mutans strains, but they inhibited some of the tested strains. Thus, the cariogenic tendency may vary between infant formulas containing different types of oligosaccharides.

Clinical efficacy and the antimicrobial potential of silver formulations in arresting dental caries: a systematic review

BackgroundThe use of silver-formulation as microbicide to arrest dentinal caries is gaining popularity. The primary objective of the present appraisal was to systematically review the clinical (in vivo) applications and antimicrobial potential of silver-containing formulations in arresting dentinal caries. Our secondary aim was to sum up the available in vitro applications of silver-containing formulations against cariogenic microbes isolated from dentine lesions.MethodsOvid MEDLINE, EBSCO host, Web of Science, and Cochrane Library databases was searched between January 2009–May 2019.ResultsIn vivo: We observed conflicting evidence of antimicrobial efficacy of SDF on a diverse array of microbial taxa present in carious dentine of primary and permanent teeth. Moreover, there is insufficient evidence on the application of AgNP-fluoride as an effective microbicidal against cariogens of dentine lesions.In vitro: We found a good evidence of microbicidal efficacy of silver diamine fluoride (SDF) on selective cariogenic microbes in human dentine model. Additionally, a good evidence was noted of in vitro application of silver nanoparticles (AgNPs) as a useful microbicidal against S. mutans adhesion, growth and subsequent biofilm formation in human dentine models.ConclusionsTaken together, in vitro evidence indicates the promising antimicrobial potential of silver-based formulations (SDF and nanosilver) against the predominant cariogenic flora, particularly from dentine lesions. Post-treatment clinical data of either the bactericidal and bacteriostatic effects of SDF or nanosilver are sparse. Furthermore, the current understanding of the specific size, concentration, antimicrobial mechanisms, and toxicological aspects of nano-silver compounds is inadequate to draw firm conclusions on their clinical utility.

The effect of calcium on the adhesion of Streptococcus mutans to Human Gingival Epithelial Cells in the presence of probiotic bacteria Lactobacillus plantarum and Lactobacillus salivarius

IntroductionOral pathogens are among the most common bacterial infections in humans. The adhesion of probiotic bacteria to epithelial cells plays an important role in inhibiting the growth and binding of pathogenic bacteria. We aim to investigate the effect of calcium carbonate on the binding of Streptococcus mutans to Human Gingival Epithelial Cells (HGECs) in the presence of the probiotic bacteria Lactobacillus plantarum and Salivarius. Methods and materialsExperiments are performed in the presence of calcium and probiotic bacteria and HGECs in duplicate and three times separately. The difference in the amount of Streptococcus mutans in HGECs is determined by the presence and absence of Lactobacillus plantarum or salivarius and calcium or both by dilution and culture procedures. ResultsSimple effects analysis showed that the survival rate of HGECs in all doses was significantly higher than negatives (p < .001). The results indicated that the survival rate in the single dose of L. salivarius (0.617 ± 0.003) and L. plantarum (0.652 ± 0.002) was significantly higher than the combined doses. ConclusionThis study clearly demonstrates that calcium and probiotics from Lactobacillus salivarius and plantarum alone can improve the survival of HGECs in the presence of Streptococcus mutans. But the combined function of these therapeutic factors is not optimal and even reduces their therapeutic efficacy.

Effect of color differences on elastomeric ligatures adhesion on streptococcus mutans in saliva liquid

Objective: Of this study was to determine the effect of color differences in elastomeric ligatures on the adhesion of streptococcus mutans in salivary fluidMaterial and Methods: Type of research used was laboratory experimental with cross sectional study, using elastomeric ligatures 10 pieces of orthodontic elastomeric ligatures dark clear fruits. The samples were then divided into 2 groups. Each group of samples was each immersed in 100 cc of artificial saliva pH 4 which had been given each cc of streptococcus mutans and cultured in the media to see the number of colonies attached to elastomeric ligatures. The results of calculating the number of colonies were then analyzed using the SPSS version 24 program and using the Independent t test with a significant value of 0.05.Results: The results showed that there are significant differences between the ligatures elastomeric orthodontic dark and elastomeric ligatures clear.Conclusion: Elastomeric ligatures darker color have more adhesion to streptococcus mutans when compared to adhesion streptococcus mutans to elastomeric ligatures clear.

Evaluation of Surface Roughness and Microbial Biofilm Adhesion of Different Orthodontic Arch-wires

Objectives: To assess the capability of different orthodontic arch-wires to retain oral biofilm and to correlate the adhesion to surface roughness of the wires. Methods: Four types of orthodontic arch- wires were used for the study, Nickel-titanium (NiTi), Copper nickel-titanium (Cu-NiTi) , Beta Titanium (TMA ) & Beta III Titanium (CNA) new arch wires and 4 weeks after intraoral usage, were examined for Surface roughness (SR) using an atomic force microscope (AFM). Adhesion of Streptococcus mutans (MS), Staphylococcus aureus (SA), and Candida albicans (CA) were performed using colony count method. Statistically, the following tests were done: analysis of variance, Pearson correlation coefficient test, post hoc Tukey test. Results: The four wire types showed significant increases in SR (P˂ 0.05) after 4 weeks of intra-oral usage, TMA wires recorded the highest roughness values while the lowest ones were for NiTi wires. Bacterial adhesion was detected on all wires, ANOVA showed significant differences between the wires concerning MS, SA and CA adhesion. A significant positive correlation (P=.001) was observed between bacterial adhesion and surface roughness after intra-oral exposure. Conclusions: SR of the wires increased after intra-oral use and there was a positive correlation with the biofilm adhesion.

Resin composite blocks for dental CAD/CAM applications reduce biofilm formation in vitro

ObjectivesModern dentistry is increasingly focusing on digital procedures, including CAD/CAM technologies. New materials have to resist in a demanding environment that includes secondary caries occurrence. The current study hypothesized that the microbiological behavior of different RBCs for CAD/CAM applications is better than that of their counterparts for direct restorations due to differences in the surface characteristics. MethodsBoth direct and CAD/CAM RBCs were tested. Specimens were obtained from each group, polished, cleaned, stored in artificial saliva (1w), then sterilized under UV (24h). Specimens’ surface was assessed using profilometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction; resin/filler content was assessed using thermogravimetry. After pre-incubation with sterile human saliva (24h), the microbiological behavior of the materials was assessed using four models: Streptococcus mutans adherence (2h), S. mutans biofilm formation in an orbital shaking bioreactor (24h), S. mutans biofilm formation in a continuous-flow bioreactor simulating shear forces (24h), and mixed-plaque formation in the bioreactor (24h). The viable biomass adhering to the specimens’ surfaces was measured using a tetrazolium dye-based test. Statistical analysis included verification of normality of distribution and homoscedasticity, then Oneway ANOVA and Tukey's test (α=5%). ResultsWhen using the bioreactor setup, CAD/CAM RBCs generally yielded lower S. mutans and mixed-plaque biofilm formation compared to direct RBCs. This difference was not evidenced in the first two microbiological models. Differences in manufacturing and curing processes rather than in materials’ surface roughness and composition could explain these results. SignificanceCAD/CAM RBCs are promising materials from a microbiological point of view, featuring reduced biofilm formation on their surfaces when shear conditions similar to in vivo ones are present.

The Role of Candida albicans Secreted Polysaccharides in Augmenting Streptococcus mutans Adherence and Mixed Biofilm Formation: In vitro and in vivo Studies.

The oral cavity is a complex environment harboring diverse microbial species that often co-exist within biofilms formed on oral surfaces. Within a biofilm, inter-species interactions can be synergistic in that the presence of one organism generates a niche for another enhancing colonization. Among these species are the opportunistic fungal pathogen Candida albicans and the bacterial species Streptococcus mutans, the etiologic agents of oral candidiasis and dental caries, respectively. Recent studies have reported enhanced prevalence of C. albicans in children with caries indicating potential clinical implications for this fungal-bacterial interaction. In this study, we aimed to specifically elucidate the role of C. albicans-derived polysaccharide biofilm matrix components in augmenting S. mutans colonization and mixed biofilm formation. Comparative evaluations of single and mixed species biofilms demonstrated significantly enhanced S. mutans retention in mixed biofilms with C. albicans. Further, S. mutans single species biofilms were enhanced upon exogenous supplementation with purified matrix material derived from C. albicans biofilms. Similarly, growth in C. albicans cell-free spent biofilm culture media enhanced S. mutans single species biofilm formation, however, the observed increase in S. mutans biofilms was significantly affected upon enzymatic digestion of polysaccharides in spent media, identifying C. albicans secreted polysaccharides as a key factor in mediating mixed biofilm formation. The enhanced S. mutans biofilms mediated by the various C. albicans effectors was also demonstrated using confocal laser scanning microscopy. Importantly, a clinically relevant mouse model of oral co-infection was adapted to demonstrate the C. albicans-mediated enhanced S. mutans colonization in a host. Analyses of harvested tissue and scanning electron microscopy demonstrated significantly higher S. mutans retention on teeth and tongues of co-infected mice compared to mice infected only with S. mutans. Collectively, the findings from this study strongly indicate that the secretion of polysacharides from C. albicans in the oral environment may impact the development of S. mutans biofilms, ultimately increasing dental caries and, therefore, Candida oral colonization should be considered as a factor in evaluating the risk of caries.

Assessment of Streptococcus Mutans Adhesion to the Surface of Biomimetically-Modified Orthodontic Archwires

Bacterial adhesion and biofilm formation on the surfaces of dental and orthodontic biomaterials is primary responsible for oral diseases and biomaterial deterioration. A number of alternatives to reduce bacterial adhesion to biomaterials, including surface modification using a variety of techniques, has been proposed. Even though surface modification has demonstrated a reduction in bacterial adhesion, information on surface modification and biomimetics to reduce bacterial adhesion to a surface is scarce. Therefore, the main objective of this work was to assess bacterial adhesion to orthodontic archwires that were modified following a biomimetic approach. The sample consisted of 0.017 × 0.025, 10 mm-long 316L stainless steel and NiTi orthodontic archwire fragments. For soft lithography, a polydimethylsiloxane (PDMS) stamp was obtained after duplicating the surface of Colocasia esculenta (L) Schott leaves. Topography transfer to the archwires was performed using silica sol. Surface hydrophobicity was assessed by contact angle and surface roughness by atomic force microscopy. Bacterial adhesion was evaluated using Streptococcus mutans. The topography of the Colocasia esculenta (L) Schott leaf was successfully transferred to the surface of the archwires. Contact angle and roughness between modified and unmodified archwire surfaces was statistically significant. A statistically significant reduction in Streptococcus mutans adhesion to modified archwires was also observed.

Antimicrobial activity of Lactobacillus fermentum TcUESC01 against Streptococcus mutans UA159

Dental caries is a multifactorial chronic-infection disease, which starts with a bacterial biofilm formation caused mainly by Streptococcus mutans. The use of probiotics has shown numerous health benefits, including in the fight against oral diseases. Strains of Lactobacillus fermentum have already shown probiotic potential against S. mutans, but there are still few studies. Thus, the aim of our study was to evaluate the antimicrobial activity of the inoculum and metabolites produced by L. fermentum TcUESC01 against S. mutans UA159. For this, a growth curve of L. fermentum was performed and both the inoculum and the metabolites formed in the fermentation were tested against the growth of S. mutans UA159 in agar diffusion tests, and only its metabolites were tested to determine the minimum inhibitory concentration, minimal bactericidal concentration and inhibition of cell adhesion. Inhibition of biofilm formation, pH drop and proton permeability were also tested with the metabolites. The zone of inhibition began to be formed at 14 h and continued until 16 h. The inoculum containing L. fermentum also showed zone of inhibition. The MIC for the metabolites was 1280 mg/mL and the MBC was obtained with a concentration higher than the MIC equal to 5120 mg/mL. Half of the MIC concentration (640 mg/mL) was required to inhibit S. mutans adhesion to the surface of the microplates. In the biofilm analyzes, the treatment with the metabolites in the tested concentration was not able to reduce biomass, insoluble glucans and alkali soluble compared to the control biofilm (p > 0.05). The metabolites also did not affect acid production and acid tolerance of S. mutans cells in biofilms compared to saline group (p > 0.05). Lactic acid (50.38%) was the most abundant organic acid produced by L. fermentum. This is the first report showing that the metabolites produced by the Lactobacillus fermentum TcUESC01 have a potential to be used as an antimicrobial agent against S. mutans, showing anti-adherence and bactericidal activity against planktonic cells of S. mutans. Thus, further studies should be carried out in order to better understand the antimicrobial activity of metabolites of L. fermentum TCUESC01.

Antimicrobial effect of chlorhexidine-releasing porous hydroxyapatite scaffold incorporated with human serum albumin nanoparticles

A novel antibacterial hydroxyapatite (HAp) scaffold was developed by immobilizing chlorhexidine (CHX)-loaded human serum albumin (HSA) nanoparticles on its surface via surface charge interaction using polyethylenimine (PEI). The CHX-loaded HSA nanoparticles were fabricated using a desolvation method, coated with PEI molecules (PEI-CHX-HSA), and immobilized via charge interaction on the scaffold surface. The PEI-CHX-HSA nanoparticles were observed to be well-dispersed on the scaffold surface. The agar diffusion test showed a clear inhibition zone of Streptococcus mutans around the nanoparticle-immobilized scaffold. The antibacterial activity of the scaffold was also confirmed in the S. mutans adhesion study using scanning electron and fluorescent microscopy. The results suggest that the HAp scaffold with immobilized PEI-CHX-HSA nanoparticles showed effective drug releasing behavior and antibacterial activity against S. mutans.

Proteolytic Activity of Bacillus subtilis upon κ-Casein Undermines Its "Caries-Safe" Effect.

Milk is believed to be a relatively “caries-safe” food. This belief relies on the fact that caseins, which constitute around 80% of milk’s protein content, were found to inhibit the adhesion of Streptococcus mutans to enamel and, therefore, decrease biofilm formation. While S. mutans is considered a leading cause of dental disorders, Bacillus subtilis is a non-pathogenic foodborne bacterium, frequently contaminating milk and its products. This study aimed to investigate the effects of dairy-associated foodborne bacteria such as B. subtilis on biofilm formation by S. mutans in the presence of casein proteins. Our results indicate that there is a significant decrease in total biofilm formation by S. mutans exposed to a casein protein mixture in a mono-species culture, whereas, in the co-culture with B. subtilis, an inhibitory effect of the caseins mixture on S. mutans biofilm formation was observed. Proteolytic activity analysis suggested that B. subtilis is capable of breaking down milk proteins, especially κ-casein, which enables biofilm formation by S. mutans in the presence of milk caseins. Therefore, these findings may challenge the assumption that milk is “caries-safe”, especially in a complex microbial environment.

Evaluation of adhesion of Streptococcus mutans, plaque accumulation on zirconia and stainless steel crowns, and surrounding gingival inflammation in primary molars: randomized controlled trial.

To evaluate the adhesion of Streptococcus mutans to preformed zirconia and stainless steel crowns and compare plaque accumulation and gingival inflammation over a period of 1year. Thirty children between 6 to 9years with pulpectomised bilateral mandibular primary second molars were randomly divided into zirconia/stainless steel groups. Plaque was collected from the crowns using swabs at 3, 6, 9, and 12months. Gingival and plaque index were recorded at all follow-ups. S. mutans was cultured on tryptone-yeast-cysteine-sucrose-bacitracin agar, and organisms were expressed as colony-forming units. Within-group analysis was performed using repeated measures ANOVA and between-groups using the independent T test. S. mutans were found in significantly higher numbers on the stainless steel crowns as compared with zirconia crowns at all the follow-ups. Gingival inflammation and plaque index scores were also significantly higher around the stainless steel crowns as compared with zirconia at the end of 12months follow-up. Adhesion of S. mutans to stainless steel crowns was significantly greater when compared with zirconia, and minimal gingival inflammation and plaque accumulation was found in the tooth restored with zirconia crowns as compared with stainless steel crowns. Preformed zirconia crowns prevents adhesion of S. mutans onto its surface, and reduces plaque accumulation around the crown, inflammation of surrounding gingiva compared to conventional stainless-steel crowns. Pediatric zirconia crowns could help in reducing the overall microbial density and prevalence in the oral cavity, thus reducing the caries risk in the long term.

A novel non-cytotoxic synthetic peptide, Pug-1, exhibited an antibiofilm effect on Streptococcus mutans adhesion.

The aim of this study was to evaluate the effects of synthetic peptides on the growth and biofilm formation of Streptococcus mutans and their cytotoxicity on a human keratinocyte cell line. Four pomegranate-derived peptides; Pug-1, Pug-2, Pug-3 and Pug-4 were synthesized. Streptococcus mutans (ATCC 25175 and DMST 41283) were used. The antibacterial and anti-adherence activities of the peptides were evaluated. The effect of the peptides on S. mutans glucosyltransferase (Gtf) activity was measured. The peptides' cytotoxicity was evaluated on a HaCaT cell line using an MTT assay. The bactericidal penetration depth of Pug-1 into the biofilm was investigated using confocal laser scanning microscopy (CLSM). Among the four peptides, Pug-1 (200µgml-1 ) exhibited antibacterial activity on S. mutans (DMST 41283). All peptides demonstrated anti-adherence activity. Streptococcus mutans Gtf activity was significantly inhibited by Pug-1. Interestingly, Pug-1 peptide was not cytotoxic to the HaCaT cell line. Pug-1 (100-200µgml-1 ) exhibited bactericidal penetration at approximately 50-100% of the biofilm depth. Therefore, Pug-1 might be a candidate of anticariogenic agent. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data highlighted that pomegranate-derived antimicrobial peptides (AMPs) inhibit Streptococcus mutans adhesion, virulence-associated genes and enzymes. This in vitro study supports the hypothesis that pomegranate AMPs would be noncytotoxic to human keratinocytes, with a potent anticariogenic effect via an anti-adherence mode-of-action. The present study provides evidence for further investigation of these AMPs as therapeutic and preventive agents for dental caries.

Gold Nanoclusters-Coated Orthodontic Devices Can Inhibit the Formation of Streptococcus mutans Biofilm.

Oral health is an issue that has attracted increasing attention recently. Poor oral hygiene may induce the formation of oral biofilm on orthodontic devices, and cause gingivitis and dental caries. Here, we present a strategy for modifying orthodontic devices (e.g., invisalign aligner) with quaternary ammonium (QA)-modified gold nanoclusters (QA-GNCs) as an antibiotic reagent to prevent bacterial contamination and biofilm formation. The QA-GNCs-coated aligner can efficiently inhibit the adhesion of cariogenic pathogenic Streptococcus mutans and the formation of biofilm. Moreover, the antibacterial activity of the coated QA-GNCs can be maintained for at least 3 months and after repeated usage (>3 cycles). Furthermore, the QA-GNCs coating shows excellent biosafety confirmed by the cell viability test, the hemolysis assay, and animal experiments. Our strategy for antibacterial coating has the advantages of broad applications, low cost, good stability, high antibacterial efficiency, good biocompatibility, and low risk of antibiotic contamination, which could be particularly useful in preventing infections involving implantable medical devices or wearable electronics.