Dental Plaque Microbial Resistomes of Periodontal Health and Disease and Their Changes after Scaling and Root Planing Therapy

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.

Smoking Impacts Alzheimer's Disease Progression Through Oral Microbiota Modulation

Alzheimer's disease (AD) is an important public health challenge with a limited understanding of its pathogenesis. Smoking is a significant modifiable risk factor for AD progression, and its specific mechanism is often interpreted from a toxicological perspective. However, microbial infections also contribute to AD, with oral microbiota playing a crucial role in its progression. Notably, smoking alters the ecological structure and pathogenicity of the oral microbiota. Currently, there is no systematic review or summary of the relationship between these three factors; thus, understanding this association can help in the development of new treatments. This review summarizes the connections between smoking, AD, and oral microbiota from existing research. It also explores how smoking affects the occurrence and development of AD through oral microbiota, and examines treatments for oral microbiota that delay the progression of AD. Furthermore, this review emphasizes the potential of the oral microbiota to act as a biomarker for AD. Finally, it considers the feasibility of probiotics and oral antibacterial therapy to expand treatment methods for AD.

Inferring diet, disease and antibiotic resistance from ancient human oral microbiomes

The interaction between a host and its microbiome is an area of intense study. For the human host, it is known that the various body-site-associated microbiomes impact heavily on health and disease states. For instance, the oral microbiome is a source of various pathogens and potential antibiotic resistance gene pools. The effect of historical changes to the human host and environment to the associated microbiome, however, has been less well explored. In this review, we characterize several historical and prehistoric events which are considered to have impacted the oral environment and therefore the bacterial communities residing within it. The link between evolutionary changes to the oral microbiota and the significant societal and behavioural changes occurring during the pre-Neolithic, Agricultural Revolution, Industrial Revolution and Antibiotic Era is outlined. While previous studies suggest the functional profile of these communities may have shifted over the centuries, there is currently a gap in knowledge that needs to be filled. Biomolecular archaeological evidence of innate antimicrobial resistance within the oral microbiome shows an increase in the abundance of antimicrobial resistance genes since the advent and widespread use of antibiotics in the modern era. Nevertheless, a lack of research into the prevalence and evolution of antimicrobial resistance within the oral microbiome throughout history hinders our ability to combat antimicrobial resistance in the modern era.

Oral microbiota, co-evolution, and implications for health and disease: The case of indigenous peoples

Evidence indicates that oral microbiota plays a crucial role in human health and disease. For instance, diseases with multifactorial etiology, such as periodontitis and caries, which cause a detrimental impact on human well-being and health, can be caused by alterations in the host-microbiota interactions, where non-pathogenic bacteria give way to pathogenic orange/red-complex bacterial species (a change from a eubiotic to dysbiotic state). In this scenario, where thousands of oral microorganisms, including fungi, archaea, and phage species, and their host are co-evolving, a set of phenomena, such as the arms race and Red or Black Queen dynamics, are expected to operate. We review concepts on the subject and revisit the nature of bacterial complexes linked to oral health and diseases, as well as the problem of the bacterial resistome in the face of the use of antibiotics and what is the impact of this on the evolutionary trajectory of the members of this symbiotic ecosystem. We constructed a 16SrRNA tree to show that adaptive consortia of oral bacterial complexes do not necessarily rescue phylogenetic relationships. Finally, we remember that oral health is not exempt from health disparity trends in some populations, such as Native Americans, when compared with non-Indigenous people.

Immunomodulators and Their Applications in Dentistry and Periodontics: A Comprehensive Review

The intricate interplay between the immune system and oral health has revealed opportunities for novel therapeutic interventions in dentistry and periodontics. This review article delves into the pivotal role of immunomodulators in orchestrating immune responses within the oral cavity and their applications in managing various oral and periodontal conditions. The oral environment faces many challenges, from microbial infections to tissue injuries, necessitating a precise immune response for optimal oral health maintenance. Characterized by their ability to modulate immune reactions, immunomodulators emerge as versatile tools for maintaining immune equilibrium. This is a comprehensive overview of the mechanisms through which immunomodulators exert their effects, shedding light on their dual role as regulators of both pro-inflammatory and anti-inflammatory pathways. The diverse applications of immunomodulators within dentistry are explored in depth. Immunomodulators exhibit promising outcomes from managing common oral conditions like gingivitis, periodontitis, and oral ulcers to enhancing the integration of dental implants and promoting wound healing post-surgery. This article highlights the various types of immunomodulatory agents utilized in dental practice, elucidating their mechanisms of action, routes of administration, dosages, and potential side effects.

Subgingival host-microbiome metatranscriptomic changes following scaling and root planing in grade II/III periodontitis

AIM

To assess the effects of scaling and root planing (SRP) on the dynamics of gene expression by the host and the microbiome in subgingival plaque samples.

MATERIALS AND METHODS

Fourteen periodontitis patients were closely monitored in the absence of periodontal treatment for 12 months. During this period, comprehensive periodontal examination and subgingival biofilm sample collection were performed bi-monthly. After 12 months, clinical attachment level (CAL) data were compiled and analysed using linear mixed models (LMM) fitted to longitudinal CAL measurements for each tooth site. LMM classified the sites as stable (S), progressing (P), or fluctuating (F). After the 12-month visit, subjects received SRP, and at 15 months they received comprehensive examination and supportive periodontal therapy. Those procedures were repeated at the 18-month visit, when patients were also sampled. Each patient contributed with one S, one P, and one F site collected at the 12- and 18-month visits. Samples were analysed using Dual RNA-Sequencing to capture host and bacterial transcriptomes simultaneously.

RESULTS

Microbiome and host response behaviour were specific to the site's progression classification (i.e., S, P, or F). Microbial profiles of pre- and post-treatment samples exhibited specific microbiome changes, with progressing sites showing the most significant changes. Among them, Porphyromonas gingivalis was reduced after treatment, while Fusobacterium nucleatum showed an increase in proportion. Transcriptome analysis of the host response showed that interleukin (IL)-17, TNF signalling pathways, and neutrophil extracellular trap formation were the primary immune response activities impacted by periodontal treatment.

CONCLUSIONS

SRP resulted in a significant "rewiring" of host and microbial activities in the progressing sites, while restructuring of the microbiome was minor in stable and fluctuating sites.

Influence of Environmental Factors on Salivary Microbiota and Their Metabolic Pathway: Next-Generation Sequencing Approach

The current study aimed to investigate the effect of periodontitis and long-term heavy metal (HM) exposure on the salivary microbiome. The patients were divided into four groups as Wu Wei control (WWC) group involved healthy individuals, Wu Wei periodontitis (WWP) patients having periodontitis, Jing Chang with metal pollution periodontally healthy individuals (JCP), and Kuang periodontitis (KP). The most abundant bacteria identified at the phylum level in the WWC group were Bacteroides, Firmicutes, and Fusobacteria. Firmicutes were observed in a significantly higher proportion in the KP group than in the WWC, WWP, and JCP. At the genus level, the WWC has major dominating bacterial genera (such as Leptotrichia, Neisseria, and Fusobacterium) which were similar to WWP and KP group. The significant difference (p < 0.05) was found in alpha diversity while in beta diversity, the significant (p = 0.005) results were found among the four groups. The correlation of oral microbiota revealed that HMs present in the soil (Cr, Ni, and Cu) are associated with the growth of Capnocytophaga, Selenomonas, Aggregatibacter, and Campylobacter. The bacterial functions in the KP group were higher in translation and nucleotide metabolism than in the WWP group. This demonstrated that long-term exposure to HMs can influence the salivary microbiota which can alter the functioning, and diversity of bacteria.

Managing Oral Health in the Context of Antimicrobial Resistance

The oral microbiome plays a major role in shaping oral health/disease state; thus, a main challenge for dental practitioners is to preserve or restore a balanced oral microbiome. Nonetheless, when pathogenic microorganisms install in the oral cavity and are incorporated into the oral biofilm, oral infections, such as gingivitis, dental caries, periodontitis, and peri-implantitis, can arise. Several prophylactic and treatment approaches are available nowadays, but most of them have been antibiotic-based. Given the actual context of antimicrobial resistance (AMR), antibiotic stewardship in dentistry would be a beneficial approach to optimize and avoid inappropriate or even unnecessary antibiotic use, representing a step towards precision medicine. Furthermore, the development of new effective treatment options to replace the need for antibiotics is being pursued, including the application of photodynamic therapy and the use of probiotics. In this review, we highlight the advances undergoing towards a better understanding of the oral microbiome and oral resistome. We also provide an updated overview of how dentists are adapting to better manage the treatment of oral infections given the problem of AMR.

Antibiotic Resistance in Patients with Peri-Implantitis: A Systematic Scoping Review

The implementation of adjunctive antibiotics has been recommended for the therapy of peri-implantitis (PI). In this review, antibiotic resistance patterns in PI patients were assessed. A systematic scoping review of observational studies and trials was established in conjunction with the PRISMA extension for scoping reviews. The SCOPUS, PubMed/MEDLINE, EMBASE, SCIELO, Web of Science, and LILACS databases were reviewed along with the gray literature. The primary electronic examination produced 139 investigations. Finally, four observational studies met the selection criteria. These studies evaluated 214 implants in 168 patients. Porphyromonas gingivalis and Fusobacterium nucleatum mainly presented high resistance to tetracycline, metronidazole, and erythromycin in PI patients. Similarly, Aggregatibacter&nbsp;actinomycetemcomitans was also highly resistant to clindamycin and doxycycline. Other microorganisms such as Tannerella forsythia, Parvimonas micra, and Prevotella intermedia/nigrescens also presented significant levels of resistance to other antibiotics including amoxicillin, azithromycin, and moxifloxacin. However, most microorganisms did not show resistance to the combination amoxicillin metronidazole. Although the management of adjunctive antimicrobials in the therapy of PI is controversial, in this review, the resistance of relevant microorganisms to antibiotics used to treat PI, and usually prescribed in dentistry, was observed. Clinicians should consider the antibiotic resistance demonstrated in the treatment of PI patients and its public health consequences.

Effect of Gum Arabic on plaque-induced gingivitis: A randomised controlled trial

New approaches to treating periodontal diseases aim to balance sustaining the natural oral microbiota and modifying the host immune response. Gum Arabic (GA) is a natural polysaccharide rich in prebiotics.

The aim of this study was to assess the effect of GA on clinical (Plaque Index (PI), Gingival Index (GI)) and immunological (Gingival Crevicular Fluid Interleukin 1 Beta (GCF IL-1 β)) parameters in patients with plaque-induced gingivitis.

Materials and methods

This placebo-controlled, double-blinded randomised clinical trial was conducted at the Department of Periodontology at Khartoum Dental Teaching Hospital, Khartoum, Sudan, from July to October 2016. Patients diagnosed with plaque-induced gingivitis meeting the study eligibility criteria were enrolled. At baseline, PI, GI and GCF IL-1β were measured. Patients received full-mouth scaling and were randomly assigned to receive either GA powder (intervention group) or Microcrystalline cellulose powder (placebo group). The patients were instructed to apply the treatment twice a day throughout the study. The PI, GI and GCF IL-1β were reassessed after 30 and 60 days.

Results

A total of 60 patients were enrolled (30 in each group). Compared to the placebo group, the intervention group showed a statistically significant reduction in GI scores after 30 days and improved PI scores at 30 and 60 days. Between baseline and 60 days, patients who received GA exhibited a significant reduction in GCF IL-1β levels compared to the placebo group.

Conclusion

GA was found to be effective in controlling plaque and gingivitis.

Clinical Trial Registration. ISRCTN registry ISRCTN14209449.

Outside the limits of bacterial viability: postbiotics in the management of periodontitis

Periodontitis is a major cause of tooth loss in adults worldwide and is caused by an unbalanced oral microbiota in a susceptible host, ultimately leading to tissue breakdown and bone loss. Traditionally, the treatment for periodontitis is scaling and root planing; however, some cases require adjuvant therapy, such as antibiotics administration or surgery. Various factors are involved in the pathogenesis and interact in an unpredictable way, increasing the complexity of the disease and making it difficult to manage. In this context, the administration of probiotics aimed at resolving bacterial dysbiosis and the associated dysregulation of the immune system has been employed in clinical trials with encouraging results. However, the use of viable microorganisms is not risk-free, and immunocompromised patients may develop adverse effects. Therefore, the use of inactivated microbial cells, cell fractions, or soluble products and metabolites of probiotics, known as postbiotics, has gained increasing attention. In this commentary, we present the current literature assessing the impact of postbiotics on the growth and metabolism of periodontal pathogens, as well as on the progression of periodontitis in rodents and humans. We also discuss the limitations of the available data and what the scientific community should consider in order to transfer this innovative therapeutic modality from the bench to the bedside.