The virulence of Streptococcus mutans and the ability to form biofilms

Oral health status in children with chronic kidney disease, kidney transplantation, and nephrotic syndrome: a cross-sectional study

INTRODUCTION

Chronic kidney disease (CKD) has been previously associated with a decline in oral health. This study aimed to examine the oral health of children with CKD, nephrotic syndrome (NS), and children that received kidney transplantation (KTR).

METHODS

A case-control study was conducted involving children with CKD stages 1-3, children with CKD stages 4-5, pediatric kidney transplant recipients, and children with NS. Developmental Defects of Enamel (DDE) were evaluated using the DDE Index, while dental caries was assessed with the Decayed Missing Filled Teeth Index (DMFT). Plaque and debris were measured utilizing the Simplified Oral Hygiene Index (OHI-S), which includes the two subindices Simplified Calculus Index (CI-S) and Simplified Debris Index (DI-S).

RESULTS

Children with CKD 1-3, CKD 4-5, and KTR presented with significantly higher DI-S and CI-S scores and significantly more DDE. There was no difference in the DMFT score in children with CKD 4-5 and KTR. For children with CKD 1-3, a significantly lower DMFT score was observed compared to the control group. Children with NS did not show any differences for DI-S, CI-S, DMFT, and DDE compared to healthy peers.

CONCLUSION

Oral health status is not affected in children with NS. Children with CKD 1-3, CKD 4-5, and KTR have more plaque, debris, and DDE and should be surveyed regularly by their dentists.

Predictive Analysis of Dental Caries Risk via Rapid Urease Activity Evaluation in Saliva Using a ZIF-8 Nanoporous Membrane

Despite a decrease in the incidence of dental caries over the past four decades, it remains a widespread public health concern. The multifactorial etiology of dental caries complicates effective prevention and early intervention efforts, underscoring the need for the development of rapid predictive methods that account for multiple factors. In this study, we selected the activity of urease secreted by Streptococcus salivarius as a metabolic marker for dental caries. This activity was quantified by measuring the diffusion of hydroxide ions generated from the urease catalytic reaction on urea across a ZIF-8-modified nanoporous membrane. The choice of ZIF-8 was based on its preference in transporting hydroxide ions, enabling the accurate detection of urease activity at concentrations as low as 1 CFU/mL. Subsequently, we collected 287 saliva samples to determine the Michaelis constant (Km) of urease using this method. Logistic regression analysis revealed that both the Km of urease and the frequency of sugar intake are significant factors influencing the development of dental caries. Furthermore, we developed a machine learning methodology for identifying dental caries, achieving an accuracy rate of 81%. It is expected that increasing the sample size will further enhance the predictive accuracy of the model. This innovative approach provides valuable insights into early intervention strategies in the fight against dental caries.

A Critical Review on the Potential of Inactivated Bacteria in Counteracting Human Pathogens

Bacterial infections are a major global public health challenge, especially with increasing antibiotic resistance. Postbiotics, bioactive compounds produced by probiotics, have been proposed as a novel strategy to inhibit the growth of pathogenic bacteria and address antibiotic resistance. Similar to probiotics and certain food ingredients, postbiotics can also modulate beneficial microbial communities and ultimately contribute to host health. Postbiotics derived from probiotics may affect the physical and chemical conditions of the intestinal environment, and by enhancing the host's immune system, directly interfere with the metabolic pathways and signaling of pathogenic bacteria. Postbiotics inhibit biofilm formation, reduce the expression of antibiotic resistance genes, and enhance the efficacy of antibiotic therapies. They are effective against resistant bacteria such as Escherichia coli and Clostridium difficile and reduce the risk of dental infections caused by Streptococcus mutans. Some postbiotics, such as lactic acid and antimicrobial peptides derived from Lactobacillus and Bifidobacterium genus, help the immune system dealing resistant bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, and Helicobacter pylori. The review investigates the mechanisms of action and applications of postbiotics in the control of pathogenic bacteria and their role as a complement to existing treatments.

Mapping Review of the Correlations Between Periodontitis, Dental Caries, and Endocarditis

Background/Objectives: The correlation between cardiovascular diseases, particularly infective endocarditis, and oral disorders such as periodontitis and dental caries has been widely discussed in the scientific literature. In this mapping review, we aim to examine the available evidence on the link between these conditions, focusing on the pathogenetic mechanisms that underlie the development of endocarditis in patients with oral diseases. Methods: A systematic search was conducted across three major databases-PubMed, Scopus, and ScienceDirect-as well as grey literature in Google Scholar. Relevant articles were selected based on inclusion and exclusion criteria, focusing primarily on systematic reviews. The data extracted included study characteristics, main outcomes, and risk-of-bias evaluations. Results: A total of 13 systematic reviews were included in this mapping review. The findings suggest there is a significant connection between periodontal disease, dental caries, and the incidence of infective endocarditis. The evidence highlights that oral bacteria, particularly Streptococcus species, can enter the bloodstream during daily activities and invasive dental procedures, contributing to the development of endocarditis in susceptible individuals. However, the role of antibiotic prophylaxis in preventing endocarditis following dental procedures remains controversial. Conclusions: This review reinforces the importance of oral health in preventing cardiovascular complications, especially infective endocarditis. Although antibiotic prophylaxis may reduce the risk in high-risk individuals, further research is needed to clarify its effectiveness. Enhanced awareness of and education on the shared risks between oral and cardiovascular health could improve prevention strategies and patient outcomes.

Microbiological and molecular aspects of periodontitis pathogenesis: an infection-induced inflammatory condition

Periodontitis (PD) is the most common oral infectious disease. The primary etiologic cause of the onset and development of PD is dental plaque, which consists of bacterial biofilm domiciled within a complex extracellular mass. In PD patients, there is a progressive breakdown of the periodontal ligament and the alveolar bone. In more advanced stages, tooth loss occurs. The progression of this chronic inflammatory disease involves interactions among numerous microbial pathogens particularly, bacteria, the host's immune factors, and various environmental factors. Due to persistent infection by periodonto-pathogenic bacteria, there is an impairment of both innate and acquired immunity, leading to tissue destruction. Chronic inflammation in PD may be associated with several systemic diseases, including cardiovascular conditions, respiratory issues, diabetes, neurological diseases, cancer, and adverse pregnancy outcomes. Antibiotic treatment is one of the effective strategies for treating PD cases, although the emergence of some resistant strains may limit the effectiveness some antibiotics. In this review study, we discussed the main bacteria in PD, the interaction with the immune response, the pathogenesis of bacteria in PD and antibiotic treatment. We also outlined the emergence of resistance to antibiotics among these pathogens.

Polymicrobial detection and salivary metabolomics of children with early childhood caries

Background

Early childhood caries (ECC) has been proposed to be associated with various microorganisms and metabolites. This study aims to compare the prevalence of specific microbial species and salivary metabolomics profile in children with and without ECC, and to explore the correlation between salivary metabolites and targeted microbes.

Method

Five ml of unstimulated saliva was collected from 32 ECC and 22 caries-free children. Clinical indexed were recorded and questionnaires regarding oral health and dietary habits were obtained from the guardians. The presence of eight specific microbial species were examined using species-specific quantitative PCR (qPCR). Untargeted metabolomics was analyzed to identify key differential metabolites and pathways. Correlations among clinical, microbial, and metabolomic data were further explored.

Results

The prevalence of Scardovia wiggsiae (90.6%, P < 0.001), Streptococcus mutans (43.8%, P = 0.006), Streptococcus sobrinus (62.5%, P < 0.001), Ligilactobacillus salivarius (93.6%, P = 0.01) and Candida albicans (56.3%, P < 0.001) were significantly higher in the ECC group. The prevalence of ECC was higher in children with two targeted species present compared with children with one targeted species. Histidine metabolism and branched-chain amino acids degradation were activated in ECC group, while glyoxylate and dicarboxylate metabolism, purine and pyrimidine metabolism were inhibited. Histidine and glutathione metabolism was activated with enrichment of targeted microbial species, while linoleic acid metabolism and biotin metabolism was inhibited. The duration of each toothbrushing was a significant risk factor for ECC experience.

Conclusion

The prevalence of Scardovia wiggsiae, Streptococcus mutans, Streptococcus sobrinus and Candida albicans is higher in ECC children compared to caries-free children. Oral habits and salivary metabolites also vary between ECC and caries-free children.

Effects of opuB on the growth and biofilm formation of Streptococcus mutans under acid stress

Streptococcus mutans (S. mutans) is a primary oral cariogenic bacterium. The OpuB transporter regulates osmotic pressure in Bacillus subtilis; however, its role in S. mutans remains unexplored. Our earlier research indicated that, under acid stress, the OpuB ABC-transport pathway in S. mutans membrane vesicles undergoes significant changes, implying its critical role in the bacterium's response to environmental stress. In this study, we constructed an opuB-deficient strain (Smu_opuB) and compared it with the wild-type strain. The results revealed that knocking out opuB enhanced the survival of planktonic S. mutans in an acidic environment, increased extracellular polysaccharide and biofilm production under acid stress, altered biofilm structure, and upregulated the expression of related virulence factors. These findings imply that opuB is instrumental in regulating acid resistance and biofilm formation in S. mutans, thereby conferring a survival advantage. This study provides compelling evidence of opuB being pivotal in S. mutans' acid resistance and biofilm formation, deepening our understanding of its functional mechanisms and establishing a foundation for future research on its role in S. mutans.

Medicinal Plants Against Dental Caries: Research and Application of Their Antibacterial Properties

Dental caries remains one of the most widespread global health concerns, significantly affecting both oral and overall health. Conventional treatments typically rely on chemical-based products which, although effective, are often associated with undesirable side effects such as tooth staining, altered taste, and the development of antimicrobial resistance. As a response, plant-based natural alternatives have gained attention as promising strategies for the prevention and management of dental caries. This review highlights the antibacterial properties of medicinal plants and their potential applications in dentistry, with a particular focus on their activity against a broad range of bacteria and microorganisms involved in oral diseases. Numerous plant extracts and bioactive compounds-including polyphenols, flavonoids, and essential oils-have demonstrated antimicrobial, anti-inflammatory, and antioxidant properties that contribute to maintaining oral health. Although in vitro and in vivo studies support their therapeutic potential, clinical trials assessing long-term efficacy and safety remain scarce. Future research should prioritize the standardization of extraction methods, dosage, and formulations to facilitate the integration of these natural alternatives into conventional dental care practices.

Isolation, probiotic characterization and genomic analysis of Enterococcus durans VIT3 from edible curd

Enterococcus species are recognized as probiotics with well-documented beneficial effects on human health. We aimed to isolate Enterococcus species from edible curd, a commonly consumed food product. The isolated bacterium is identified to be Enterococcus durans VIT3 by Oxford nanopore sequencing. The isolate is susceptible to commonly used antibiotics with no hemolysis activity. The isolate exhibited probiotic characteristics, like resistance to acid and bile, significant adhesion capability, auto-aggregation, and antimicrobial activity against pathogenic bacteria such as C. violaceum, S. mutans, S. enterica and S. aureus. E. durans VIT3 can efficiently scavenge the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, shows a potential anti-oxidant activity. Whole genome analysis revealed a total length of 3.2 Mb with 37.9 average GC content, which included genes associated with probiotic functions.

Antimicrobial and Antibiofilm Properties of Hydroxyapatite/Nano-Hydroxyapatite in Preventing Dental Caries: A Systematic Review

Controlling biofilm is a crucial strategy and an essential component of preventing dental caries. Considerable research has been conducted in recent years on the clinical application of hydroxyapatite (HAp) and hydroxyapatite nanoparticles (nHAp) in preventing dental caries. However, these studies have yet to investigate the effectiveness or mechanism of these substances as antibacterial and antibiofilm agents. This study aimed to provide a thorough analysis of the current evidence on the antibacterial and antibiofilm characteristics of HAp/nHAp in the prevention of dental caries. Searches were conducted across five databases: Cochrane Library, PubMed, Scopus, EBSCOhost, and ScienceDirect. Google Scholar was also searched. Titles, abstracts, and full text were evaluated following the guidelines set by the Preferred Reporting Item for Systematic Review and Meta-Analyses (PRISMA). A methodological quality assessment of the studies was conducted using the QUIN tool. The initial retrieval totaled 15,047 studies, from which 3,487 were excluded. A total of 11,560 studies were screened based on the title and abstract, resulting in 24 full-text studies considered potentially eligible for inclusion (κ = 0.9599). Finally, 19 studies met all the defined inclusion criteria and were included in this comprehensive systematic review (κ = 0.8837). HAp/nHAp demonstrates antimicrobial activities against gram-negative and gram-positive bacteria and fungi. However, nHAp's antibiofilm efficacy remains limited. Further investigation is required to improve the efficacy of antibacterial and antibiofilm agents.

Effect of Cudrania tricuspidata on Cariogenic Properties and Caries-Related Gene Expression in Streptococcus mutans

The purpose of this study was to evaluate the gene expression pattern of the caries-inhibiting effect of Cudrania tricuspidata (C. tricuspidata) extract on cariogenic bacteria Streptococcus mutans (S. mutans). We examined bacterial growth, tooth surface attachment, biofilm formation, acid production, free calcium release, and toxicity gene expression. The major components of the extract were investigated by UPLC-Q-TOF-MS analysis. Exposure to C. tricuspidata inhibited bacterial growth and attachment at concentrations of ≥15 μg/mL. Inhibition effects on biofilm formation, acid production, and free calcium release due to acid production were observed at concentrations ≥ 30 μg/mL. S. mutans virulence gene expression analysis showed that it inhibited the expression of gbpB and spaP, which mediate bacterial attachment to the tooth surface, and that of genes contributing to biofilm formation (gtfB, gtfC, and gtfD) and acid resistance (brpA and relA), and regulation (vicR). Analysis using UPLC-Q-TOF-MS/MS showed that the main component was phenylpropanoids. These results suggest that C. tricuspidata may inhibit the cariogenic properties associated with the expression of caries-related genes in S. mutans.

Dental plaque-inspired peptide engineered to control plaque accumulation

Effective control of plaque accumulation is an important strategy for reducing the risk of both localized oral health issues and systemic diseases associated with plaque. However, existing approaches for preventing plaque accumulation exhibit some limitations, such as insufficient compatibility with the oral microbiota and tissues, as well as inconvenience in their use. Herein, inspired by dental plaque, a new class of peptides featuring excellent anti-fouling performance is successfully developed. Our peptides consist of a salivary-acquired peptide with tooth surface-selective adhesion, a zwitterionic peptide with anti-adhesion property, and four proline residues that provide structural rigidity. We conduct a series of progressive experiments, including molecular dynamics simulation and assessments of the anti-fouling performance of our peptides on hydroxyapatite slices, human tooth enamel slices, and ex vivo human teeth. The results demonstrate that our peptides possess the abilities of rapid anchoring on tooth surfaces and effective inhibiting protein and bacterial adhesion. These characteristics enable our peptide to efficiently control plaque accumulation through rinsing or spraying while preserving the balance of the oral microbiota. These findings open an appealing avenue for the development of anti-fouling agents for controlling plaque accumulation on tooth surfaces.

Natural compounds: new therapeutic approach for inhibition of Streptococcus mutans and dental caries

Streptococcus mutans is recognized as one of the leading causes of dental caries, and biofilm formation by this bacterium plays a key role in dental plaque development and caries progression. Given the increasing resistance of bacteria to antibiotics and the adverse effects of some synthetic antimicrobials, the search for natural alternatives has received increasing attention. The recently published studies have demonstrated that natural compounds (NCs) such as curcumin, cinnamaldehyde, eugenol, thymol, carvacrol, epigallocatechin gallate, farnesol, catechin, inulin, menthol, apigenin, myricetin, oleanolic acid, and resveratrol, have notable antimicrobial properties and can effectively inhibit the growth of Streptococcus mutans. NCs can disrupt bacterial membrane integrity, leading to cell death, and possess the capability to inhibit acid production, which is a key factor in caries development. NCs can also interfere with bacterial adhesion to surfaces, including teeth. The attachment inhibition is achieved by decreasing the expression of adhesion factors such as gtfs, ftf, fruA, and gbpB. NCs can disrupt bacterial metabolism, inhibit biofilm formation, disperse existing biofilm, and interfere with quorum sensing and two-component signal transduction systems. Moreover, novel drug delivery platforms were used to enhance the bioavailability and stability of NCs. Studies have also indicated that NCs exhibit significant efficacy in combination therapies. Notably, curcumin has shown promising results in photodynamic therapy against S. mutans. The current review article analyzes the mechanisms of action of various NCs against S. mutans and investigates their potential as alternative or complementary therapeutic options for managing this bacterium and dental caries.

Comparison of Color Stability and Surface Roughness of Interim Crowns Fabricated by Conventional, Milling and 3D Printing Methods

OBJECTIVES

Manufacturing temporary restorations is part of the treatment process in fixed prostheses, which is accomplished by different methods. The aim of this study is to compare the color stability and surface roughness of provisional crowns made by 3D printing, conventional and milling methods.

MATERIALS AND METHODS

In this semi-experimental study, 60 provisional crowns were created by conventional, milling, and 3D printing methods (20 samples for each method). Half of the samples in each group were treated with BisCover surface sealant after construction. The surface roughness was checked using a laser profilometer. To determine the color stability, an evaluation was done using a spectrophotometer on the first day and the second and fourth weeks after exposure to the tea solution, and ∆E was calculated using L*a*b* values. Statistical analysis was performed at a significance level of 0.05.

RESULTS

The surface roughness in the conventional group was significantly higher than in the milling group (p < 0.05). The surface-treated samples had less surface roughness and more color stability than other samples (p < 0.05). ∆E in the 3D printing group was higher than other groups in all time intervals (p < 0.05).

CONCLUSION

The milling method can be considered the best method of making provisional crowns in terms of color stability and surface smoothness. Also, the use of sealing materials can have a significant effect on improving color stability and surface smoothness in provisional crowns made by any method.

Dendritic polyglutamic acid-chelerythrine nanocomplex for the reversal of bacterial tooth decay

Caries begin with an imbalance between demineralization and remineralization due to the continuous acid production by cariogenic bacteria. However, the development of dental materials that could prevent and treat caries via a simple and efficient mechanism has always been a challenge. To address this issue, therapeutic nanoparticles composed of a dendritic polyglutamic acid (DPGlu) and chelerythrine (CHE) complex (DPGlu@CHE) were developed via hydrophobic interactions and hydrogen bonds. DPGlu@CHE could be adsorbed onto the tooth surface, releasing CHE rapidly under acidic conditions to remove cariogenic bacteria, subsequently inducing tooth surface remineralization in situ. Our results demonstrated that more than 99% of Streptococcus mutans on the tooth surface were killed, and 84% of the mechanical properties of tooth were restored within 2 weeks. Thus, DPGlu@CHE was proven to be a safe and effective enamel restoration material in vitro, and its safety was verified in vivo, making it a promising mouthwash ingredient to maintain dental health.

Influence of Polyphosphate on the Mineralization Balance of Tooth Enamel

Dental minerals are in an equilibrium state of demineralization and remineralization, which can be disrupted by pathogenic bacteria to cause dental caries. While the inorganic polymer polyphosphate (polyP) is ubiquitous in living organisms and is also widely involved in mineralization regulations, its specific influence on the mineralization balance of teeth remains unclear. As a concept-and-proof study, the effects of polyP on the demineralization and remineralization of teeth are investigated on dental enamel (the highly mineralized outer covering tissue of teeth) from the perspective of mineralization balance. We found that a high concentration (containing 1.0-20 mM P element, comparable to and higher than the free phosphate ions in body fluids) of polyP has the capability to demineralize enamel in the aqueous solution, yet this effect is absent in the simulated biological environments including simulated body fluid and MEM (α-minimum essential medium) solutions. More importantly, polyP with a very low concentration (containing ≥5.0 μM P) is able to inhibit enamel mineralization significantly. This suggests that polyP could impact the mineralization balance of enamel by preferentially inhibiting the remineralization process, thereby disrupting the equilibrium necessary for maintaining enamel health.

In vitro effect of photodynamic therapy with two photosensitizers on Streptococcus mutans load around metal and ceramic brackets bonded to enamel

BACKGROUND AND OBJECTIVES

The inherent surface porosities of ceramic brackets can enhance bacterial plaque accumulation. This study assessed the in-vitro effect of photodynamic therapy (PDT) with two photosensitizers (PSs) on Streptococcus mutans (S. mutans) load around metal and ceramic brackets bonded to enamel.

MATERIALS AND METHODS

In this in vitro experimental study, 48 sound premolars extracted for orthodontic reasons were randomly assigned to two groups (n = 24) for bonding to metal and ceramic brackets. After bracket bonding, the tooth-bracket assemblies were inoculated with S. mutans, and each group was randomly divided into three subgroups (n = 8) of control, PDT with toluidine blue O (TBO) and 635 nm laser, and PDT with indocyanine green (ICG) and 808 nm laser. The colony count was quantified in each subgroup, and analyzed by repeated measures ANOVA.

RESULTS

Ceramic brackets showed a significantly higher colony count than metal brackets in the control subgroup by 7.057 log10 CFUs/mL (P < 0.05). PDT, irrespective of PS type, significantly decreased the bacterial count around both ceramic (by 7.616 log10 CFUs/mL in the ICG and 7.594 log10 CFUs/mL in the TBO subgroup) and metal (by 7.512 log10 CFUs/mL in the ICG and 7.505 log10 CFUs/mL in the TBO subgroup) brackets (P < 0.05). The difference in bacterial count was not significant between the ceramic and metal bracket groups after PDT (P = 0.541 for ICG and P = 0.101 for TBO).

CONCLUSION

Within the limitations of this in vitro study and as an attempt to predict what might happen in vivo, the results showed that PDT significantly decreased the bacterial load around metal and ceramic brackets bonded to enamel, irrespective of the type of PS. Thus, PDT may be considered as a possibly efficient strategy to minimize the bacterial load especially around ceramic brackets.

Streptococcus mutans biofilms in the establishment of dental caries: a review

Dental caries is considered as the most common and multifactorial disease worldwide, caused by a variety of oral microorganisms like Streptococcus spp., Veillonella spp., Actinomyces spp., Bifidobacterium spp., and Lactobacillus fermentum, which colonize food debris in oral cavities. Of them, Streptococcus mutans is the predominant bacterium and can induce progressive tooth destruction, especially during dentition. The superior characteristics of S. mutans, such as the presence of the cell surface protein P1 and exopolysaccharide-synthesizing enzymes, acid tolerance, biofilm-forming ability mediated by brpA gene, and multidrug resistance, render it a highly virulent pathogen in the etiology of dental caries. Given its significant role in dental caries, extensive research has been conducted over the past few decades, focusing on the development of specific antimicrobial treatments, and other innovative therapeutic approaches. To gain deeper insights into the genetic diversity and epidemiological patterns of S. mutans, various genotypic methods have been developed and successfully employed. By combining the insights gained from genetic studies of S. mutans with the suitable control measures against the biofilm, we can develop innovative and effective strategies for preventing and treating dental caries.

Fabrication and evaluation of BerNPs regarding the growth and development of Streptococcus mutans

In this study, berberine nanoparticles (BerNPs) were prepared using a wet-milling method with zirconium balls to enhance bioavailability and expand potential applications. The particle size and physicochemical properties of the BerNPs were analyzed using field-emission scanning electron microscopy (FE-SEM), UV-vis spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The broth dilution method was used to determine the antimicrobial activity of the BerNPs against Streptococcus mutans (S. mutans). The impact of the BerNPs on the cell surface of S. mutans was evaluated through FE-SEM analysis, focusing on its ability to inhibit biofilm formation. The results demonstrated that BerNPs were produced with an average particle size of 40-65 nm. The chemical structure of BerNPs remained consistent with that of berberine, with no modifications occurring during nanoparticle preparation. The BerNPs exhibited the ability to inhibit S. mutans, with minimum inhibitory concentration and minimum bactericidal concentration values of 78.1 and 312.5 µg/mL, respectively. BerNPs caused significant damage to S. mutans cells, disrupting the cell membrane structure, and leading to cell lysis and death. Additionally, BerNPs effectively inhibited the biofilm formation of S. mutans. In summary, BerNPs demonstrated a potent inhibitory effect on the activities of S. mutans at selectively applied concentrations.

Functional modification and antibacterial evaluation of orthodontic adhesives with poly (lysine)-derived carbon dots

Fixed appliances used in orthodontic treatment make oral hygiene difficult to maintain, leading to bacterial adhesion around brackets and consequently resulting in white spot lesions (WSLs). After the bracket debonding, the residual adhesive is difficult to remove precisely due to its appearance similar to tooth enamel. In this study, we successfully synthesized small-sized and highly active PL-CDs by one-pot pyrolysis using ε-poly-l-lysine as a precursor. It was incorporated into orthodontic adhesives for multi-function modification. Based on our experimental results, the 3 wt% PL-CDs modified orthodontic adhesive exhibited excellent antibacterial properties and color identifiability. The addition of 3 wt% PL-CDs did not affect the biocompatibility and mechanical properties of the adhesive, and the cell survival rate was up to 80%. Therefore, this study provides a new strategy to solve the two major problems of enamel white spot and adhesive removal in the process of fixed orthodontics, and has important clinical application.

Preparation of dental resin composites with anti-bacterial adhesion against Streptococcus mutans using fluorinated and silicon containing dimethacrylates

OBJECTIVE

The purpose of this study was to enhance the anti-bacterial adhesion effect against Streptococcus mutans (S. mutans) of fluorinated dimethacrylate (DF MA) based dental resin composites (DRCs) by using silicone dimethacrylate (SMA-MEO).

METHOD

The SMA-MEO was added into mixture of DFMA and tricyclo (5.2.1.0) decanedimethanol diacrylate (SR833s) (DFMA/SR833s = 50 wt./50 wt.) with mass ratios of 10 wt% and 20 wt% to form resin matrix both with fluorinated and silicon containing dimethacrylates, and then DRCs named DS+ 10 %SMA-MEO and DS+ 20 %SMA-MEO were prepared by mixing the resin matrix with silaned BaAlSiO2 filler particles at a mass ratio of 30 wt./70 wt. Double bond conversion, volumetric shrinkage and shrinkage stress, flexural strength and modulus, water sorption and solubility, contact angle and surface free energy, anti-bacterial adhesion effect against Streptococcus mutans (S. mutans), and cytotoxicity of prepared DRCs were investigated according to standard or referenced methods. Fluorinated dimethacrylate (DFMA) based DRC named DS and 2,2-bis[4-(2-hydroxy-3-methacryloy-loxypropyl)-phenyl]propane (Bis-GMA) based DRC named BT were used as controls.

RESULTS

Adding SMA-MEO into DFMA based DRC could lead to higher double bond conversion (p < 0.05), higher hydrophobicity (p < 0.05), and lower surface free energy (p < 0.05). Only DS+ 10 %SMA-MEO had better anti-bacterial adhesion effect against S. mutans than DS (p < 0.05). The SMA-MEO had no influence on volumetric shrinkage, shrinkage stress, flexural modulus, water sorption and solubility of DRC (p > 0.05), but could reduce flexural strength of dry DRC (p < 0.05). After water immersion, SMA-MEO containing DRCs had comparable flexural strength as DS (p > 0.05). Compared with BT, DS and SMA-MEO containing DRCs had better or comparable physicochemical properties, and lower amount of adherent S. mutans. All of DRCs had comparable cytotoxicity (p > 0.05).

SIGNIFICANCE

DRCs with both DFMA and SMA-MEO could have better anti-bacterial adhesion effect against S. mutans than DRC only with DFMA due to increased hydrophobicity and decreased Surface free energy, and the optimal mass fraction of SMA-MEO in DFMA based resin matrix was 10 wt%.

Structure and mechanism of biosynthesis of Streptococcus mutans cell wall polysaccharide

Streptococcus mutans, the causative agent of human dental caries, expresses a cell wall attached Serotype c-specific Carbohydrate (SCC) that is critical for cell viability. SCC consists of a polyrhamnose backbone of →3)α-Rha(1 → 2)α-Rha(1→ repeats with glucose (Glc) side-chains and glycerol phosphate (GroP) decorations. This study reveals that SCC has one predominant and two more minor Glc modifications. The predominant Glc modification, α-Glc, attached to position 2 of 3-rhamnose, is installed by SccN and SccM glycosyltransferases and is the site of the GroP addition. The minor Glc modifications are β-Glc linked to position 4 of 3-rhamnose installed by SccP and SccQ glycosyltransferases, and α-Glc attached to position 4 of 2-rhamnose installed by SccN working in tandem with an unknown enzyme. Both the major and the minor β-Glc modifications control bacterial morphology, but only the GroP and major Glc modifications are critical for biofilm formation.

Microbial Dynamics in Endodontic Pathology-From Bacterial Infection to Therapeutic Interventions-A Narrative Review

Endodontic infection is a penetration of microorganisms into the dental pulp. Bacteria are the most common entities that induce an infection. This state is associated with significant pain and discomfort. Therapeutic intervention involves removal of infected pulp from the tooth and roots, which eliminates viable tissue, thus creating a tooth less resistant to mechanical pressure. Studies suggest that there are several types of bacteria most commonly associated with endodontic infections. Furthermore, it is considered that different types of pathogens could play a major role in primary and secondary endodontic infections. The aim of this review is to summarize major bacteria involved in the process of endodontic infection. Furthermore, we discuss the bacterial properties that allow them to penetrate dental pulp and hypothesize about possible future treatment strategies.

Oral Pathogens' Substantial Burden on Cancer, Cardiovascular Diseases, Alzheimer's, Diabetes, and Other Systemic Diseases: A Public Health Crisis-A Comprehensive Review

This review synthesizes the findings from 252 studies to explore the relationship between the oral pathogens associated with periodontitis, dental caries, and systemic diseases. Individuals with oral diseases, such as periodontitis, are between 1.7 and 7.5 times (average 3.3 times) more likely to develop systemic diseases or suffer adverse pregnancy outcomes, underscoring the critical connection between dental and overall health. Oral conditions such as periodontitis and dental caries represent a significant health burden, affecting 26-47% of Americans. The most important oral pathogens, ranked by publication frequency, include the herpes virus, C. albicans, S. mutans, P. gingivalis, F. nucleatum, A. actinomycetemcomitans, P. intermedia, T. denticola, and T. forsythia. The systemic diseases and disorders linked to oral infections, ranked similarly, include cancer, respiratory, liver, bowel, fever, kidney, complications in pregnancy, cardiovascular bacteremia, diabetes, arthritis, autoimmune, bladder, dementia, lupus, and Alzheimer's diseases. Evidence supports the efficacy of dental and periodontal treatments in eliminating oral infections and reducing the severity of systemic diseases. The substantial burden that oral pathogens have on cancer, cardiovascular diseases, Alzheimer's, diabetes, and other systemic diseases poses a significant public health crisis.

Dietary Immunoglobulin Y by Targeting Both GbpB and GtfB Enhances the Anticaries Effect in Rats

OBJECTIVE

The purpose of this work was to develop an anti-CAT-SYI immunoglobulin Y (IgY) antibody that targeted both GtfB (glucosyltransferase B) and GbpB (glucan-binding protein B) and test its anticaries properties in rats.

METHODS

A new CAT-SYI fusion gene was created utilising functional DNA fragments from the GtfB and GbpB genes. The recombinant antigens, comprising the fused CAT-SYI antigen, GtfB, and GbpB, were expressed and purified using a prokaryotic expression and purification system. The purified recombinant antigens were utilised to immunise laying hens against particular IgY production. The biological activities of these particular IgY antibodies were then assessed both in vitro and in vivo, including their capacity to suppress biofilm formation and tooth caries.

RESULTS

Results indicated that these produced IgY antibodies demonstrated a high antibody titer (>0.1 μg/mL) and could precisely recognise and bind to their respective antigens. Furthermore, it was discovered that these specific IgY antibodies successfully bind to Streptococcus mutans and significantly reduce biofilm development. After 8 weeks of ingesting antigen-specific IgY meals, comprising anti-GtfB IgY and anti-GbpB IgY, the severity of dental caries was dramatically reduced in S mutans-infected Sprague-Dawley rats (P < .01). Anti-CAT-SYI IgY therapy significantly reduced tooth cavities by 89.0% in vivo (P < .05) compared to other treatment groups.

CONCLUSIONS

The anti-CAT-SYI IgY, a multitarget antibody that targets both GtfB and GbpB, displayed excellent inhibitory effects against S mutans, making it a promising targeted method with improved anticaries efficacy and significant application opportunities.

Pathogenesis-Associated Bacterial Amyloids: The Network of Interactions

Amyloids are protein fibrils with a characteristic cross-β structure that is responsible for the unusual resistance of amyloids to various physical and chemical factors, as well as numerous pathogenic and functional consequences of amyloidogenesis. The greatest diversity of functional amyloids was identified in bacteria. The majority of bacterial amyloids are involved in virulence and pathogenesis either via facilitating formation of biofilms and adaptation of bacteria to colonization of a host organism or through direct regulation of toxicity. Recent studies have shown that, beside their commonly known activity, amyloids may be involved in the spatial regulation of proteome by modulating aggregation of other amyloidogenic proteins with multiple functional or pathological effects. Although the studies on the role of microbiome-produced amyloids in the development of amyloidoses in humans and animals have only been started, it is clear that humans as holobionts contain amyloids encoded not only by the host genome, but also by microorganisms that constitute the microbiome. Amyloids acquired from external sources (e.g., food) can interact with holobiont amyloids and modulate the effects of bacterial and host amyloids, thus adding another level of complexity to the holobiont-associated amyloid network. In this review, we described bacterial amyloids directly or indirectly involved in disease pathogenesis in humans and discussed the significance of bacterial amyloids in the three-component network of holobiont-associated amyloids.

Evaluation of residual carious dentin detection methods after cavity preparation: a randomized clinical trial

BACKGROUND

The treatment of caries in dentine poses the challenge of balancing adequate caries removal to prevent residual caries and excessive sound dentine removal. No diagnostic tool is available to define the caries removal limit clinically. This study aimed to determine the efficiency of visual-tactile, caries detector dye (CDD), and laser fluorescence (LF) device methods for diagnosing residual caries after cavity preparation.

METHOD

The study was conducted as a three-arm, double-blinded, parallel-group randomized trial at the Restorative Dentistryclinics of a teaching hospital in northeastern Nigeria. Individualized carious lesions in dentine were randomly allocated to three groups of residual caries diagnosis methods, A (visual-tactile), B (CDD), and C (LF). All carious lesions had caries excavation and cavity preparation using the visual-tactile method. Main outcome measures were based on the assessment of residual caries of prepared cavities in groups B and C with CDD and LF (DIAGNOdent Pen) respectively, and bacterial culture growth of dentine samples collected from all (A, B, and C) the preparedcavities.

DESIGN

Three-arm, double-blinded, parallel group randomized trial. A centralized randomization, into three groups A, B, and C, used opaque envelopes containing names of diagnostic methods allocated to teeth in the trail.

SETTING

Restorative Dentistry clinics of a teaching hospital in northeastern Nigeria.

PARTICIPANTS

Ninety patients with dental caries in dentine. All 90 patients met the requirements for the study.

INTERVENTION

Carious lesions were excavated, and cavity preparation was performed via the visual-tactile method. Prepared cavities in groups B and C were assessed for residual caries with CDD and LF (DIAGNOdent Pen), respectively, by a blinded independent investigator. Dentine samples were obtained from all the prepared cavities (A, B, and C) and subjected to bacterial culture. Teeth were restored and follow-up was not required.

MAIN OUTCOME MEASURES

The presence or absence of residual caries staining by CDD and fluorescence by DIAGNOdent in prepared cavities of groups B and C, respectively; the presence or absence of bacterial culture growth for all three groups.

RESULTS

Ninety participants (mean age 31.6 ± 7.480), each with one tooth with a deep carious lesion were randomized. The visual-tactile method had a specificity of 100%, CDD had 100% sensitivity and 92.9% specificity, and DIAGNOdent had 100% sensitivity and 100% specificity when measured against bacterial cultures. The positive predictive value for CDD (50%) was half that for DIAGNOdent (100%). The negative predictive value was the lowest (90%) for the visual-tactile method. The accuracy was highest (100%) for DIAGNOdent. There was perfect agreement between the DIAGNOdent and bacteriological tests (kappa = 1.00), whereas the CDD had an above-random level of agreement (kappa = 0.63).

CONCLUSIONS

All three residual caries evaluation methods were efficient, independently, in detecting residual caries in prepared cavities. DIAGNOdent was the most specific of the tested modalities and had the highest agreement with the bacteriological confirmatory test.

TRIAL REGISTRATION

PanAfrican Clinical Trial Registry (PACTR202309545839091), registered on 1st September 2023.

Biofilm targeting with chitosan-based nanohydrogel containing Quercus infectoria G. Olivier extract against Streptococcus mutans: new formulations of a traditional natural product

BACKGROUND

Biofilm formation has a crucial role in the cariogenic virulence of Streptococcus mutans, which leads to resistance to common antibacterials. The antimicrobial resistance crisis has led to increased research about traditional natural products.

PURPOSE

Quercus infectoria extract (QI extract) and nano hydrogels containing QI extract (QI-NH) and tannic acid (TA-NH) were evaluated against this pathogen.

METHODS

QI extract was analyzed by HPLC and the physiological characteristics of nanohydrogels were assessed by SEM, FTIR, zeta potential, DLS and determination of release kinetics and encapsulation efficiency. Determination of MIC and MBC of the material and their anti-biofilm effect was done by the microtiter method and on the extracted tooth surface. The properties of extracts and nano hydrogels in the expression of genes codifying glucosyltransferases (gtfB, gtfC and gtfD) and glucan binding protein B (gbpB) were quantified. Their toxicity was tested by the MTT method against the KB cell line.

RESULTS

According to HPLC, 55.18% of QI extract contained TA. The encapsulation efficiency of QI-NH and TA-NH was equal to 60% and 80%, respectively. SEM and FTIR exhibited that QI extract and TA were successfully entrapped in the networks resulting from the chemical bonding of chitosan and TPP. The average size of QI-NH and TA-NH was 70.45 and 58.43 nm, and their zeta potential was 6.17 ± 2.58 and 0.25 ± 0.03 mv, respectively. PDI < 0.3 of nano hydrogels indicated the favorable polydispersity of nanohydrogels. MIC of QI extract, QI-NH and TA-NH were 937.5, 30 and 10 µg/ml, respectively. Also their MBIC50 was 35.1, 2.1 and 0.95 µg/ml, respectively, and the extracts and nano hydrogels restrained the biofilm maturation on enamel. The pivotal genes of S. mutans in biofilm formation were significantly less expressed by treatment with QI-NH and TA-NH than others. Based on the MTT test, QI-NH had less acute toxicity than QI extract and TA-NH. IC50 of QI-NH was calculated as 775.4 µg/ml, while it was equal to 3.12 µg/ml for chlorhexidine as a common antibacterial agent.

CONCLUSION

QI-NH, a new formulation derived from traditional anti-caries, can be a safe and efficient option to combat dental biofilm.

Comparative analysis of the postadmission and antemortem oropharyngeal and rectal swab microbiota of ICU patients

Shotgun metabarcoding was conducted to examine the microbiota in a total of 48 samples from 12 critically ill patients, analyzing samples from both the oropharynx and rectum. We aimed to compare their postadmission microbiota, characterized as moderately dysbiotic, with the severely dysbiotic antemortem microbiota associated with patients' deaths. We found that, compared with postadmission samples, patient antemortem swab samples presented moderate but not significantly decreased diversity indices. The antemortem oropharyngeal samples presented an increase in biofilm-forming bacteria, including Streptococcus oralis, methicillin-resistant Staphylococcus aureus (MRSA), and Enterococcus faecalis. Although the septic shock rate was 67%, no significant differences were detected in the potential pathogen ratios when the microbiota was analyzed. A notable strain-sharing rate between the oropharynx and intestine was noted. By comparing postadmission and antemortem samples, microbial biomarkers of severe dysbiosis were pinpointed through the analysis of differentially abundant and uniquely emerging species in both oropharyngeal and rectal swabs. Demonstrating strong interconnectivity along the oral-intestinal axis, these biomarkers could serve as indicators of the progression of dysbiosis. Furthermore, the microbial networks of the oropharyngeal microbiota in deceased patients presented the lowest modularity, suggesting a vulnerable community structure. Our data also highlight the critical importance of introducing treatments aimed at enhancing the resilience of the oral cavity microbiome, thereby contributing to better patient outcomes.

Trans, Trans-Farnesol Enhances the Anti-Bacterial and Anti-Biofilm Effect of Arachidonic Acid on the Cariogenic Bacteria Streptococcus mutans and Streptococcus sobrinus

BACKGROUND

Streptococcus mutans and Streptococcus sobrinus are Gram-positive bacteria involved in the development of dental caries, as they are able to form biofilms on tooth enamel, ferment sugars into acids, and survive under acidic conditions. This ultimately leads to a local lowering of the pH value on the tooth surface, which causes enamel cavities.

HYPOTHESIS

One measure to reduce caries is to limit the growth of cariogenic bacteria by using two anti-bacterial agents with different mechanisms of action. The hypothesis of this study was that the anti-bacterial activity of ω-6 polyunsaturated arachidonic acid (AA) against S. mutans and S. sobrinus can be enhanced by the sesquiterpene alcohol trans, trans-farnesol (t,t-farnesol).

METHODS

The anti-bacterial activity of single and combined treatment was determined by the checkerboard assay. Bacterial viability was assessed by live/dead SYTO 9/propidium iodide (PI) staining on flow cytometry. Anti-biofilm activity was determined by MTT metabolic assay, crystal violet staining of biofilm biomass, SYTO 9/PI staining by spinning disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM).

RESULTS

t,t-Farnesol lowered the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) of AA at sub-MICs. AA reduced the metabolic activity of preformed mature biofilms, while t,t-farnesol had no significant effect. The enhanced anti-bacterial effect of the combined t,t-farnesol/AA treatment was further evidenced by increased PI uptake, indicating membrane perforation. The enhanced anti-biofilm effect was further verified by SDCM and HR-SEM. Gene expression studies showed reduced expression of some biofilm-related genes.

CONCLUSIONS

Altogether, our study suggests a potential use of the two naturally occurring compounds arachidonic acid and t,t-farnesol for preventing biofilm formation by the cariogenic bacteria S. mutans and S. sobrinus. These findings have implications for caries prevention.

Inhibitory effects of chlorhexidine-loaded calcium carbonate nanoparticles against dental implant infections

This study aimed to design sustained released biodegradable calcium carbonate nanoparticles loaded with chlorhexidine (CHX-loaded NPs) and to investigate the early osteogenic differentiation and antimicrobial effects on the important bacteria involved in infections of dental implants. The microemulsion method was used to prepare the calcium carbonate nanoparticles loaded with chlorhexidine. The prepared nanoparticles were characterized using conventional methods. The release pattern determination and the biodegradation test were performed for the prepared nanoparticles. For the early osteogenic differentiation test of the prepared nanoparticles, alkaline phosphatase (ALP) activity was detected in human dental pulp stem cells (HDPSCs). The antimicrobial effects of the nanoparticles were evaluated against Escherichia coli, Streptococcus mutans, Enterococcus faecalis, Staphylococcus aureus, and Pseudomonas aeruginosa. The sizes of free calcium carbonate nanoparticles and CHX-loaded NPs were 105 ± 1.63 and 118 ± 1.47 nm and their zeta potentials were - 27 and - 36, respectively. A 50% degradation of nanoparticles was achieved after 100 days. These nanoparticles showed a two-stage sustained release pattern in vitro. Microscopic images revealed that the morphology of free calcium carbonate nanoparticles primarily took on a spherical calcite form, while CHX-loaded NPs predominantly exhibited a cauliflower-like vaterite polymorph. The nanoparticles increased the activity of ALP in cells in two weeks significantly (p < 0.05). Antimicrobial and antibiofilm results showed an efficient effect of the prepared nanoparticle against the studied bacteria. Calcium carbonate nanoparticles are an efficient multifunctional vector for chlorhexidine and can be used as a bioactive antibacterial agent against various oral microorganisms to prevent implant infections.

Lacticaseibacillus rhamnosus inhibits the development of dental caries in rat caries model and in vitro

OBJECTIVES

Dental caries result from a microbial imbalance in the oral cavity. Probiotics ecologically modulate the oral microflora to prevent caries. This study evaluated the anti-cariogenic effects of two Lacticaseibacillus rhamnosus strains in vitro and in vivo to provide a more theoretical basis for its clinical applications in caries prevention.

METHODS

In the study, cariogenic biofilms were grown with L. rhamnosus (LGG) or L. rhamnosus ATCC 7469 and analyzed. Quantitative real-time PCR (qPCR), Scanning Electron Microscope (SEM), and Confocal laser scanning microscope (CLSM) were used to detect the changes in the composition and architectures; cariogenic activity was measured by the lactic acid production and Transverse Microradiography (TMR). The effects of LGG on the 12 Sprague-Dawley rat caries model were assessed using Keyes scores and micro-CT analysis. Oral microbiome changes were evaluated through 16S rRNA gene high-throughput sequencing.

RESULTS

L. rhamnosus can reduce cariogenic bacteria in biofilm by 14.7 % to 48.9 %, with LGG exhibiting more potent inhibitory effects. Both strains of L. rhamnosus can adhere to the surface of biofilms, reduce the extracellular polysaccharides (EPS) matrix, and loosen the biofilm structure. L. rhamnosus inhibited cariogenic activity by reducing the lactic acid production in biofilms. The bovine enamel blocks presented lower mineral loss values and lesion depth values in the group Core+L.rh and Core+LGG. LGG-ingested rats had significantly lower levels of moderate dentin lesions and higher mineral density than the control group. The 16 s rRNA gene sequencing revealed that LGG regulated the beta diversity of the oral microbial community in the rat dental caries model.

CONCLUSIONS

This study revealed the promising potential of L. rhamnosus, especially the LGG strain, in the ecological prevention of dental caries.

CLINICAL SIGNIFICANCE

Probiotics may provide a strategy for preventing caries by regulating the oral microecological balance. The study revealed the promising anti-caries potential of the LGG probiotic strain in vivo and in vitro. It is expected that LGG could be used as an oral probiotic for the clinical prevention and treatment of caries.

The Influence of Streptococcus mutans Biofilm Formation in a Polymicrobial Environment (Streptococcus gordonii & Porphyromonas gingivalis)

OBJECTIVES

 Biofilms play a vital role in the occurrence or worsening of an infectious disease. Streptococcus mutans is a bacterium with the ability to form biofilms that plays a key role in the development of infectious diseases such as dental caries. The formation of biofilms in S. mutans is mediated by quorum sensing. Inhibiting quorum sensing can be considered as one of the approaches to prevent caries. This study aims to investigate the ability of Streptococcus gordonii and Porphyromonas gingivalis bacteria to inhibit the formation of S. mutans biofilm.

MATERIALS AND METHODS

 This research was conducted to analyze bacterial biofilm formation and metabolism. The bacteria used are S. mutans (serotype C), S. gordonii (ATCC 5165), and P. gingivalis (ATCC 33277). Biofilm formation was analyzed using the crystal violet assay. Bacterial metabolism was analyzed using the methylthiazol tetrazolium (MTT) assay.

RESULTS

 The results of the crystal violet assay indicate a decrease in biofilm formation in S. mutans when in the presence of S. gordonii and S. mutans in the presence of P. gingivalis. The results of the MTT assay show no significant change in the bacterial metabolism of S. mutans in the presence of S. gordonii and S. mutans in the presence of P. gingivalis. However, S. mutans with the presence of S. gordonii and P. gingivalis show an increase in biofilm formation and bacterial metabolism.

CONCLUSION

 S. gordonii and P. gingivalis are each capable of inhibiting the formation of S. mutans biofilm in a polymicrobial environment.

The Effect of New Trend Electronic Cigarettes on Dental Caries in Relation to Glucosyltransferase B and Secretory Immunoglobulin A (A Case-control Study)

Electronic cigarettes (vapes) are actively used, and their use is growing globally, especially among young people. Its spread is rapid due to the presence of unproven rumors that it is used to treat smoking addiction as it aids in smoking cessation. However, E.C has a negative impact on dental health by affecting the oral microbiome and salivary components. The goal of this study was to evaluate the impact of electronic cigarettes on dental caries in relation to glucosyltransferase B and secretory immunoglobulin in the saliva of electronic cigarette users. Ninety active males were divided into two groups: 45 electronic-cigarette smokers in addition to 45 non-electronic-cigarette smokers as a control group. An oral examination was performed on the studied groups, and decayed missing filling tooth surfaces (DMFS) were documented. Additionally, unstimulated saliva was collected to evaluate salivary glucosyltransferase B and secretory immunoglobulin A by using a sandwich enzyme-linked immune-sorbent assay (ELISA). The obtained outcomes showed that decayed, missing, and filled Surfaces values(DMFS), salivary glucosyltransferase B, and salivary secretory immunoglobulin A were greater in the study group than in control group. Additionally, a correlation between glucosyltransferase B, secretory immunoglobulin A, and DMFS was positive and significant. It was concluded that e-cigarettes may have an effect on saliva components and dental caries.

Antibacterial Activity of Novel Agent N-2-Hydroxypropyl Trimethyl Ammonium Chloride Chitosan against Streptococcus mutans

Dental caries (DC) is one of the most common oral diseases and is mainly caused by Streptococcus mutans (S. mutans). The use of antibiotics against S. mutans usually has side effects, including developing resistance. N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC), a natural product, has great potential utility in antibacterial agents owing to its low toxicity and good biocompatibility. Thus, the purpose of the present study was to explore the antimicrobial activity of N-2-HACC against S. mutans through the permeability of the cell wall, integrity of cell membrane, protein and nucleic acid synthesis, respiratory metabolism, and biofilm formation. Our results confirmed that the MIC of N-2-HACC against S. mutans was 0.625 mg/mL with a 90.01 ± 1.54% inhibition rate. SEM observed the formation of cavities on the surface of S. mutans after 12 h N-2-HACC treatment. The level of alkaline phosphatase (AKP) activity was higher in the N-2-HACC treatment group than in the control group, indicating that N-2-HACC can improve the permeability of the cell wall. Also, N-2-HACC treatment can destroy the cell membrane of S. mutans by increasing conductivity and absorbance at 260 nm, decreasing cell metabolic activity, and enhancing the fluorescence at 488 nm. Respiratory metabolism revealed that the activities of the Na+-K+-ATP enzyme, pyruvate kinase (PK), succinate dehydrogenase (SDH), and malate dehydrogenase (MDH) were decreased after N-2-HACC treatment, revealing that N-2-HACC can inhibit glycolysis and the tricarboxylic acid cycle (TCA cycle) of S. mutans. Moreover, N-2-HACC can also decrease the contents of the nucleic acid and solution protein of S. mutans, interfere with biofilm formation, and decrease the mRNA expression level of biofilm formation-related genes. Therefore, these results verify that N-2-HACC has strong antibacterial activity against S. mutans, acting via cell membrane integrity damage, increasing the permeability of cell walls, interfering with bacterial protein and nucleic acid synthesis, perturbing glycolysis and the TCA cycle, and inhibiting biofilm formation. It is suggested that N-2-HACC may represent a new potential synthetically modified antibacterial material against S. mutans.

Partial in-vitro dispersal of S. mutans UA159 biofilms by silver-(I)cyanoximate compounds

Silver(I) cyanoximate compounds have antibacterial activity against the oral pathogen Streptococcus mutans, a resident of oral plaque biofilm. As oral biofilm strategies focus on the inhibition of attachment or physical removal of the existing microbes, we were interested in exploring the ability of six different silver(I) cyanoximate compounds to target and disperse a pre-existing biofilm. Here we report that these compounds were only able to partially disperse S. mutans biofilms as the compounds were more effective at inhibiting biofilm formation. None of the six compounds were able to outperform silver nitrate, a commonly used antibacterial in dentistry.

Trans-Cinnamaldehyde Inhibition of Pyruvate Dehydrogenase: Effects on Streptococcus mutans Carbohydrate Metabolism

Dental caries is a chronic oral infectious disease, and Streptococcus mutans (S. mutans) plays an important role in the formation of dental caries. Trans-cinnamaldehyde (CA) exhibits broad-spectrum antibacterial activity; however, its target and mechanism of action of CA on S. mutans needs to be further explored. In this study, it was verified that CA could inhibit the growth and biofilm formation of S. mutans. Further proteomic analysis identified 33, 55, and 78 differentially expressed proteins (DEPs) in S. mutans treated with CA for 1, 2, and 4 h, respectively. Bioinformatics analysis showed that CA interfered with carbohydrate metabolism, glycolysis, pyruvate metabolism, and the TCA cycle, as well as amino acid metabolism of S. mutans. Protein interactions suggested that pyruvate dehydrogenase (PDH) plays an important role in the antibacterial effect of CA. Moreover, the upstream and downstream pathways related to PDH were verified by various assays, and the results proved that CA not only suppressed the glucose and sucrose consumption and inhibited glucosyltransferase (GTF) and lactate dehydrogenase (LDH) activities but also decreased the ATP production. Interestingly, the protein interaction, qRT-PCR, and molecular docking analysis showed that PDH might be the target of CA to fight S. mutans. In summary, the study shows that CA interferes with the carbohydrate metabolism of bacteria by inhibiting glycolysis and the tricarboxylic acid (TCA) cycle via binding to PDH, which verifies that PDH is a potential target for the development of new drugs against S. mutans.

Post-translational modification by the Pgf glycosylation machinery modulates Streptococcus mutans OMZ175 physiology and virulence

Streptococcus mutans is commonly associated with dental caries and the ability to form biofilms is essential for its pathogenicity. We recently identified the Pgf glycosylation machinery of S. mutans, responsible for the post-translational modification of the surface-associated adhesins Cnm and WapA. Since the four-gene pgf operon (pgfS-pgfM1-pgfE-pgfM2) is part of the S. mutans core genome, we hypothesized that the scope of the Pgf system goes beyond Cnm and WapA glycosylation. In silico analyses and tunicamycin sensitivity assays suggested a functional overlap between the Pgf machinery and the rhamnose-glucose polysaccharide synthesis pathway. Phenotypic characterization of pgf mutants (ΔpgfS, ΔpgfE, ΔpgfM1, ΔpgfM2, and Δpgf) revealed that the Pgf system is important for biofilm formation, surface charge, membrane stability, and survival in human saliva. Moreover, deletion of the entire pgf operon (Δpgf strain) resulted in significantly impaired colonization in a rat oral colonization model. Using Cnm as a model, we showed that Cnm is heavily modified with N-acetyl hexosamines but it becomes heavily phosphorylated with the inactivation of the PgfS glycosyltransferase, suggesting a crosstalk between these two post-translational modification mechanisms. Our results revealed that the Pgf machinery contributes to multiple aspects of S. mutans pathobiology that may go beyond Cnm and WapA glycosylation.

Three-Dimensional-Printed Modular Titanium Alloy Plates for Osteosynthesis of the Jawbone

BACKGROUNDS

The titanium-aluminum-vanadium alloy (Ti-6Al-4V) is frequently used in implantology due to its biocompatibility. The use of 3D printing enables the mechanical modification of implant structures and the adaptation of their shape to the specific needs of individual patients.

METHODS

The titanium alloy plates were designed using the 3D CAD method and printed using a 3D SLM printer. Qualitative tests were performed on the material surface using a microcomputed tomography scanner. The cytotoxicity of the modular titanium plates was investigated using the MTT assay on the L929 cell line and in direct contact with Balb/3T3 cells. Cell adhesion to the material surface was evaluated with hFOB1.19 human osteoblasts. Microbial biofilm formation was investigated on strains of Lactobacillus rhamnosus, Staphylococcus epidermidis, Streptococcus mutans and Candida albicans using the TTC test and scanning electron microscopy (SEM).

RESULTS

The surface analysis showed the hydrophobic nature of the implant. The study showed that the titanium plates had no cytotoxic properties. In addition, the material surface showed favorable properties for osteoblast adhesion. Among the microorganisms tested, the strains of S. mutans and S. epidermidis showed the highest adhesion capacity to the plate surface, while the fungus C. albicans showed the lowest adhesion capacity.

CONCLUSIONS

The manufactured modular plates have properties that are advantageous for the implantation and reduction in selected forms of microbial biofilm. Three-dimensional-printed modular titanium plates were investigated in this study and revealed the potential clinical application of this type of materials, regarding lack of cytotoxicity, high adhesion properties for osteoblasts and reduction in biofilm formation. The 3D CAD method allows us to personalise the shape of implants for individual patients.

Role of Moringa oleifera irrigation solution on the cell metabolism change of Streptococcus mutans

The principal etiological agent responsible for dental caries is Streptococcus mutans (S. mutans). The Moringa oleifera (M. oleifera) possesses antioxidant and antibacterial properties that function through the response to oxidative stress, which affects bacterial cell metabolism. This research examined M. oleifera impact on S. mutans growth, toxicity, glucan-binding protein (GBP) expression, and nucleic acid structure. Methods included spectrophotometry for growth analysis, enzyme-linked immunosorbent assay for GBP quantification, the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) MTT assay for cytotoxicity, Fourier transform infrared for nucleic acid changes, and docking simulation for ligand-receptor affinity. Results showed that M. oleifera significantly inhibited S. mutans growth at all concentrations over 24 and 48 h (optical density <0.1), comparable to <300 CFU/mL. At 72 h, 6.25% and 3.125% concentrations were most effective, with chlorhexidine also showing stability at these times. A 3.125% concentration of M. oleifera notably reduced GBP production to below 15% and caused cell toxicity. Furthermore, 25% and 3.125% concentrations significantly altered S. mutans nucleic acids, and M. oleifera showed high binding affinity to the GBP gene receptor. Thus, M. oleifera can inhibit S. mutans growth and GBP production, cause nucleic acid deformation, and strongly bind to the GBP receptor, highlighting its potential in dental caries prevention.

Characterizations of biogenic selenium nanoparticles and their anti-biofilm potential against Streptococcus mutans ATCC 25175

INTRODUCTION

S. mutans has been identified as the primary pathogenic bacterium in biofilm-mediated dental caries. The biogenic selenium nanoparticles (SeNPs) produced by L. plantarum KNF-5 were used in this study against S. mutans ATCC 25175.

OBJECTIVES

The aims of this study were: (1) the biosynthesis of SeNPs by L. plantarum KNF-5, (2) the characterization of SeNPs, (3) the investigation of the inhibitory effect of biogenic SeNPs against S. mutans ATCC 25175, and (4) the determination of the anti-biofilm potential of SeNPS against S. mutans ATCC 25175.

METHODOLOGY

3 mL of the culture was added to 100 mL of MRS medium and incubated. After 4 h, Na2SeO3 solution (concentration 100 μg/mL) was added and incubated at 37 °C for 36 h. The color of the culture solution changed from brownish-yellow to reddish, indicating the formation of SeNPs. The characterization of SeNPs was confirmed by UV-Vis spectrophotometry, FTIR, SEM-EDS and a particle size analyzer. The antibacterial activity was determined by the disk diffusion method, the MIC by the micro-double dilution method, and the biofilm inhibitory potential by the crystal violet method and the MTT assay. The effect of SeNPs on S. mutans ATCC 25175 was determined using SEM and CLSM spectrometry techniques. The sulfate-anthrone method was used to analyze the effect of SeNPs on insoluble extracellular polysaccharides. The expression of genes in S. mutans ATCC 25175 was analyzed by real-time quantitative polymerase chain reaction (RT-qPCR).

PREPARATION OF NANOPARTICLES

SeNPs produced by probiotic bacteria are considered a safe method. In this study, L. plantarum KNF-5 (probiotic strain) was used for the production of SeNPs.

RESULTS

The biogenic SeNPs were spherical and coated with proteins and polysaccharides and had a diameter of about 270 nm. The MIC of the SeNPs against S. mutans ATCC 25175 was 3.125 mg/mL. Biofilm growth was also significantly suppressed at this concentration. The expression of genes responsible for biofilm formation (GtfB, GtfC, BrpA and GbpB,) was reduced when S. mutans ATCC 25175 was treated with SeNPs.

CONCLUSION

It was concluded that the biogenic SeNPs produced by L. plantarum KNF-5 was highly effective to inhibit the growth of S. mutans ATCC 25175.

NOVELTY STATEMENT

The application of biogenic SeNPs, a natural anti-biofilm agent against S. mutans ATCC 25175. In the future, this study will provide a new option for the prevention and treatment of dental caries.

Antibacterial, Antibiofilm, and Tooth Color Preservation Capacity of Magnesium Oxide Nanoparticles Varnish (in vitro Study)

Purpose

Antibacterial and antibiofilm properties of magnesium oxide nanoparticles (MgONPs) mixture assessed against Streptococcus mutans (S. mutans), in addition to examining MgONPs varnish impact on the preservation of the tooth color and inhibition of methylene blue diffusion to the enamel.

Methods

MgONPs mixture was prepared in deionized water (DW), absolute ethanol (E), and rosin with ethanol (RE), named varnish. The antibacterial and antibiofilm capacities of MgONPs mixtures were tested by agar well diffusion, colony-forming unit (CFU), and biofilm inhibition microtiter methods in triplicate and compared to sodium fluoride varnish (NaF) and chlorhexidine mouthwash (ChX). A spectrophotometer was used to record basic tooth color. The artificial demineralization was initiated for 96 h. Then, experimental materials were applied to the corresponding group, and 10-day pH cycles proceeded. Then, the color was recorded in the same ambient environment. The methylene blue diffusion was evaluated by staining the samples for 24 h. After that, the diffusion test was calculated by a digital camera attached to the stereomicroscope.

Results

The agar well diffusion test expressed a significant inhibition zone with all MgONPs mixtures (p = 0.000), and maximum inhibition zone diameter associated with MgONPs-RE. The same finding was observed in the CFU test. Additionally, 2.5%, 5%, and 10% MgONPs-RE varnish showed strong biofilm inhibition capacity (p = 0.039) compared to NaF and ChX groups that inhibit biofilm formation moderately (p = 0.003). The study shows that the 5% MgONPs-RE varnish maintains basic tooth color with minimal methylene blue diffusion compared to NaF varnish (p = 0.00).

Conclusion

Evaluating MgONPs as a mixture revealed antibacterial and antibiofilm capacity against S. mutans with a higher effect of MgONPs-RE varnish. Also, examining the topical effect of MgONPs-RE varnish on the preservation of the tooth color after pH cycle challenges and methylene blue diffusion to enamel confirmed the high performance of MgONPs-RE varnish at 5%.

Quantifying variations associated with dental caries reveals disparity in effect allele frequencies across diverse populations

BACKGROUND

Dental caries (DC) is a multifaceted oral condition influenced by genetic and environmental factors. Recent advancements in genotyping and sequencing technologies, such as Genome-Wide Association Studies (GWAS) have helped researchers to identify numerous genetic variants associated with DC, but their prevalence and significance across diverse global populations remain poorly understood as most of the studies were conducted in European populations, and very few were conducted in Asians specifically in Indians.

AIM

This study aimed to evaluate the genetic affinity of effect alleles associated with DC to understand the genetic relationship between global populations with respect to the Indian context.

METHODOLOGY

This present study used an empirical approach in which variants associated with DC susceptibility were selected. These variants were identified and annotated using the GWAS summary. The genetic affinity was evaluated using Fst.

RESULTS

The effect of allele frequencies among different populations was examined, revealing variations in allele distribution. African populations exhibited higher frequencies of specific risk alleles, whereas East Asian and European populations displayed distinct profiles. South Asian populations showed a unique genetic cluster.

CONCLUSION

Our study emphasises the complex genetic landscape of DC and highlights the need for population-specific research as well as validation of GWAS-identified markers in Indians before defining them as established candidate genes.

Multi-acrylamides improve bond stability through collagen reinforcement under physiological conditions

OBJECTIVES

Acrylamides were shown to significantly improve bonding stability in adhesive restorations, but the reinforcement mechanism has not been fully elucidated. We tested the hypothesis that hydrogen bonding reinforcement of the collagen network (with secondary or tertiary acrylamides), as well as degree of crosslinking of the polymer network (with di- or tri-functional acrylamides), can be two of the factors at play.

METHODS

Two-step total etch adhesives comprising UDMA (60 wt%) and 40 wt% of: TAAEA, TMAAEA (secondary, tertiary tri-acrylamides), BAAP, DEBAAP (secondary, tertiary di-acrylamides) or HEMA (mono-methacrylate - control) were formulated. Simulated composite restorations (n = 5) were tested after cyclic mechanical and biological (S. mutans biofilm) challenges. Gap formation before and after aging was assessed with SEM imaging. Micro-tensile bond strength (μTBS, n = 6) was assessed after seven-day incubation in water or S. mutans-containing culture medium. Collagen reinforcement was assessed with hydroxyproline assay (n = 10) and rheology (n = 3). Data were analyzed with one-way/two-way ANOVA/Tukey's test (alpha=5%).

RESULTS

Gap formation increased and bond strength decreased for all monomers after biofilm incubation (p < 0.001). Except for DEBAAP, secondary and tertiary di/tri-acrylamides showed lower occlusal gap width values, but no significant differences overall gap length compared to HEMA. μTBS increased for tri-acrylamides compared with HEMA. Samples treated with multi-acrylamides had lower concentration of hydroxyproline (by-product of collagen degradation) (p < 0.001), except for DEBAAP, which showed values close to HEMA (p > 0.05). Dentin shear modulus increased for all acrylamides after 72 h, especially TMAAEA.

SIGNIFICANCE

In general, multi-acrylamides promote collagen reinforcement, leading to reduced gap formation, and stabilize the bond strength under physiological conditions.

An insight into the last 5-year patents on Porphyromonas gingivalis and Streptococcus mutans, the pivotal pathogens in the oral cavity

INTRODUCTION

The oral cavity harbors an extensive array of over 700 microorganisms, forming the most complex biome of the entire human body, with bacterial species being the most abundant. Oral diseases, e.g. periodontitis and caries, are strictly associated with bacterial dysbiosis. Porphyromonas gingivalis and Streptococcus mutans stand out among bacteria colonizing the oral cavity.

AREAS COVERED

After a brief overview of the bacterial populations in the oral cavity and their roles in regulating (flora) oral cavity or causing diseases like periodontal and cariogenic pathogens, we focused our attention on P. gingivalis and S. mutans, searching for the last-5-year patents dealing with the proposal of new strategies to fight their infections. Following the PRISMA protocol, we filtered the results and analyzed over 100 applied/granted patents, to provide an in-depth insight into this R&D scenario.

EXPERT OPINION

Several antibacterial proposals have been patented in this period, from both chemical - peptides and small molecules - and biological - probiotics and antibodies - sources, along with natural extracts, polymers, and drug delivery systems. Most of the inventors are from China and Korea and their studies also investigated anti-inflammatory and antioxidant effects, being beneficial to oral health through a prophylactic, protective, or curative effect.

The Influence of Vitamin D Levels on Dental Caries: A Retrospective Study of the United States Population

(1) Background: This study examines vitamin D's impact on dental caries to inform prevention strategies, given its critical role in bone and calcium regulation, vital for dental health. (2) Methods: Data from 18,683 participants of the National Health and Nutrition Examination Survey (NHANES) 2011-2016 were analyzed. NHANES collects U.S. population data through interviews, physical exams, and tests, including vitamin D levels and dental health assessed using both the decayed, missing, and filled teeth (DMFT) index and the presence of untreated dental caries. Vitamin D levels were measured according to serum 25(OH)D concentrations, and the analyses adjusted for confounders such as body mass index (BMI) and socioeconomic status (SES) using Chi-square, Mann-Whitney U, Kruskal-Wallis tests, as well as logistic and Poisson regression. (3) Results: This study found a mean DMFT score of 7.36 and a 33.2% prevalence of untreated dental caries. A higher caries prevalence was correlated with a lower SES (p < 0.001), the male gender (p < 0.001), and a higher BMI (p < 0.001). Severe vitamin D deficiency (<25 nmol/L) doubled the risk of dental caries, with odds ratios of 2.261 and 1.953 after adjusting for demographic factors and BMI. (4) Conclusions: Our study confirms a significant relationship between low vitamin D levels and an increased risk of dental caries nationwide, even after accounting for sociodemographic factors, emphasizing the importance of maintaining sufficient vitamin D levels for preventing caries.

Antibacterial activities of Miang extracts against selected pathogens and the potential of the tannin-free extracts in the growth inhibition of Streptococcus mutans

Bacterial pathogens have remained a major public health concern for several decades. This study investigated the antibacterial activities of Miang extracts (at non-neutral and neutral pH) against Bacillus cereus TISTR 747, Escherichia coli ATCC 22595, Salmonella enterica serovar Typhimurium TISTR 292 and Streptococcus mutans DMST 18777. The potential of Polyvinylpolypyrrolidone (PVPP)-precipitated tannin-free Miang extracts in growth-inhibition of the cariogenic Streptococcus mutans DMST 18777 and its biofilms was also evaluated. The tannin-rich fermented extracts had the best bacterial growth inhibition against S. mutans DMST 18777 with an MIC of 0.29 and 0.72 mg/mL for nonfilamentous fungi (NFP) Miang and filamentous-fungi-processed (FFP) Miang respectively. This observed anti-streptococcal activity still remained after PVPP-mediated precipitation of bioactive tannins especially, in NFP and FFP Miang. Characterization of the PVPP-treated extracts using High performance liquid chromatography quadrupole-time of flight-mass spectrometry (HPLC-QToF-MS) analysis, also offered an insight into probable compound classes responsible for the activities. In addition, Crystal violet-staining also showed better IC50 values for NFP Miang (4.30 ± 0.66 mg/mL) and FFP Miang (12.73 ± 0.11 mg/mL) against S. mutans DMST 18777 biofilms in vitro. Homology modeling and molecular docking analysis using HPLC-MS identified ligands in tannin-free Miang supernatants, was performed against modelled S. mutans DMST 18777 sortase A enzyme. The in silico analysis suggested that the inhibition by NFP and FFP Miang might be attributed to the presence of ellagic acid, flavonoid aglycones, and glycosides. Thus, these Miang extracts could be optimized and explored as natural active pharmaceutical ingredients (NAPIs) for applications in oral hygienic products.

Influence of post-processing on the adhesion of dual-species biofilm on polylactic acid obtained by additive manufacturing

Introduction

Post-processing (PP) is performed to improve the surface, which can favor microbial adhesion and consequent pathological manifestations that impair the indication of polylactic acid (PLA) obtained by fused filament fabrication (FFF) for biomedical applications. This aims to evaluate the influence of chemical, thermal, and mechanical PP on the adhesion of Streptococcus mutants and Candida albicans, roughness, and wettability of the PLA obtained by FFF with and without thermal aging.

Methods

The specimens were designed in the 3D modeling program and printed. The chemical PP was performed by immersion in chloroform, the thermal by the annealing method, and the mechanical by polishing. Thermal aging was performed by alternating the temperature from 5 °C to 55 °C with 5000 cycles. Colony-forming unit (CFU/mL) counting was performed on dual-species biofilm of C. albicans and S. mutans. Roughness was analyzed by rugosimeter and wettability by the sessile drop technique. Data were verified for normality using the Shapiro-Wilk test, two-way ANOVA (α = 0.05) applied for CFU and wettability, and Kruskal-Wallis (α = 0.05) for roughness.

Results

Chemical, thermal, and mechanical PP methods showed no influence on CFU/mL of C. albicans (p = 0.296) and S. mutans (p = 0.055). Thermal aging did not influence microbial adhesion. Chemical PP had lower roughness, which had increased after aging. Wettability of the mechanical PP was lower.

Conclusions

Post-processing techniques, do not present an influence on the adhesion of S. mutans and C. albicans in PLA obtained by FFF, chemical PP reduced roughness, and mechanical reduced wettability. Thermal aging did not alter the microbial adhesion and altered the roughness and wettability.

Comparative Lipidomics of Oral Commensal and Opportunistic Bacteria

The oral cavity contains a vast array of microbes that contribute to the balance between oral health and disease. In addition, oral bacteria can gain access to the circulation and contribute to other diseases and chronic conditions. There are a limited number of publications available regarding the comparative lipidomics of oral bacteria and fungi involved in the construction of oral biofilms, hence our decision to study the lipidomics of representative oral bacteria and a fungus. We performed high-resolution mass spectrometric analyses (<2.0 ppm mass error) of the lipidomes from five Gram-positive commensal bacteria: Streptococcus oralis, Streptococcus intermedius, Streptococcus mitis, Streptococcus sanguinis, and Streptococcus gordonii; five Gram-positive opportunistic bacteria: Streptococcus mutans, Staphylococcus epidermis, Streptococcus acidominimus, Actinomyces viscosus, and Nanosynbacter lyticus; seven Gram-negative opportunistic bacteria: Porphyromonas gingivalis. Prevotella brevis, Proteus vulgaris, Fusobacterium nucleatum, Veillonella parvula, Treponema denticola, and Alkermansia muciniphila; and one fungus: Candida albicans. Our mass spectrometric analytical platform allowed for a detailed evaluation of the many structural modifications made by microbes for the three major lipid scaffolds: glycerol, sphingosine and fatty acyls of hydroxy fatty acids (FAHFAs).