Ecological approaches to oral biofilms: control without killing

Inter-kingdom interactions and environmental influences on the oral microbiome in severe early childhood caries

Dental caries arise from intricate interactions among oral microorganisms, impacting ecological stability and disease progression. In this study, we aimed to investigate the microbial diversity and inter-kingdom interactions in severe early childhood caries (S-ECC) and assess the influence of environmental factors such as salivary pH and trace elements. We analyzed 61 children aged 3-4 years with complete deciduous dentition, evaluating salivary pH, buffering capacity, and trace elements (iron, fluoride). We examined the performance of 16S rRNA V1-V9 regions gene and internal transcribed spacer (ITS) primers for bacteria and fungi from plaque and saliva to characterize community compositions and diversity. Findings revealed significant shifts in bacterial diversity in S-ECC saliva samples, marked by decreased diversity and elevated abundance of cariogenic species, particularly Streptococcus mutans. Candida albicans was notably more prevalent in the S-ECC group, implicating its potential role in pathogenesis. Iron and fluoride concentrations showed no significant correlation with microbial community structure. Network analyses uncovered complex intra- and inter-kingdom interactions, underscoring cooperative and competitive dynamics. S-ECC children exhibited higher abundances of bacteria (Streptococcus mutans, Granulicatella, Actinomyces) and fungi (Candida albicans), with specific microbial taxa associated with reduced salivary pH.

IMPORTANCE

This study illuminates the intricate relationship between bacteria and fungi within the oral microbial community of children, specifically highlighting differences between those with S-ECC and those without caries. Through an extensive analysis of the microbial composition in both saliva and dental plaque, we identified a significant increase in the abundance of specific bacterial taxa (e.g., S. mutans, Granulicatella, Actinomyces) and fungal species (e.g., C. albicans) in the oral cavities of children with S-ECC. This finding underscores the potential role of these microorganisms in the development of caries. Contrary to previous studies that emphasize the importance of iron and fluoride in oral health, our research found no significant correlation between the concentrations of these elements and the composition of oral microbial communities. This result challenges conventional understanding and opens new avenues for future research. Additionally, our findings revealed an association between Veillonella sp., Propionibacterium sp., and Candida sp. and reduced salivary pH. This provides novel insights into the relationship between the oral microenvironment and caries development. The implications of our findings are substantial for the development of prevention and intervention strategies targeting childhood caries. They also underscore the critical need for a deeper exploration of oral microbial interactions and their environmental influences.

A Pyrroloquinazoline Analogue Regulated Streptococcus mutans and Streptococcus sanguinis Dual-Species Biofilms

OBJECTIVE

Selective inhibition of cariogenic bacteria is regarded as a potential strategy against caries. To assess the potential of SCH-79797, one novel promising antibiotic, in microbial equilibrium using a dual-species biofilms model of Streptococcus mutans (S. mutans) and Streptococcus sanguinis (S. sanguinis).

METHODS

Biofilm biomass and metabolic activity were disclosed using the MTT and crystal violet staining methods. Besides, bacteria/exopolysaccharide staining and anthrone method were applied to measure extracellular polysaccharides (EPS) synthesis, while lactic acid measurement was used to assess acid production. Then, quantitative real-time PCR (qRT-PCR) was employed to investigate gene variation related to polysaccharide production and interspecies competition within dual-species biofilm. The dual-species biofilm configuration was mirrored by fluorescence in situ hybridization (FISH). Growth of the planktonic bacteria was reflected by growth curve. Lastly, bacterial cell membranes were visualized by transmission electron microscope (TEM).

RESULTS

Within dual-species biofilm, SCH-79797 not only abated biomass, metabolic activity, EPS as well as acid generation but also decreased the proportion of opportunistic cariogenic S. mutans. Besides, polysaccharides production and competition-related genes (gtfP, spxB) in S. sanguinis were up-regulated, whereas these associated genes (gtfB, gtfC, gtfD, and nlmD) in S. mutans were down-regulated inside dual-species biofilm which displayed decreased S. mutans ratio. Additionally, SCH-79797 had a selective inhibitory effect on S. mutans rather than S. sanguinis, including biofilm's biomass, metabolic activity, acid and polysaccharides generation, bacterial growth, and cell membrane integrity.

CONCLUSIONS

SCH-79797 showed regulatory effects on controlling dual-species biofilm ecologically, indicating its potential to be a latent anticaries agent.

The Oral Microbiome and Systemic Health: Bridging the Gap Between Dentistry and Medicine

The oral microbiome, consisting of a mixture of bacteria, fungi, and viruses, is an important contributor to oral and systemic health. Microbial balance disruptions are associated with oral pathologies like dental caries and periodontitis as well as systemic diseases such as cardiovascular diseases, adverse pregnancy outcomes, and respiratory diseases. This review explores the mechanistic pathways linking oral dysbiosis to systemic inflammation, endothelial dysfunction, and immune modulation. The roles of key microbial species in health and disease are analyzed, with an emphasis on how hematogenous dissemination leads to systemic pathologies through inflammatory signaling. Also, advances in high throughput sequencing are discussed, as well as microbial diversity and its implications for diagnostics and therapeutics. The review highlights the potential of oral microbiota-targeted interventions to mitigate systemic diseases through dentistry and medicine integration, by throwing light on interdisciplinary strategies. Future work should focus on the evaluation of the mechanisms by which the oral microbiome plays a role in systemic diseases through the integration of multi-omics approaches such as metagenomics, transcriptomics, and metabolomics. Furthermore, clinical trials need to be designed in a way to evaluate the efficacy of microbiome-targeted therapies in the prevention of cardiovascular diseases, adverse pregnancy outcomes, and autoimmune disorders.

Botanicals as promising antimicrobial agents for enhancing oral health: a comprehensive review

The mouth houses the second largest diversity of microorganisms in the body, harboring more than 700 bacterial species colonizing the soft mucosa and hard tooth surfaces. Microbes are the cause of several health-related problems, such as dental carries, gingivitis, periodontitis, etc., in the mouth across different age groups and socioeconomic/demographic groups. Oral infections are major health problems that affect the standard of living. Compromised oral health is related to chronic conditions and systemic disorders. Microbes responsible for dental caries are acid-producing and aciduric Gram-positive bacteria (Streptococci, Lactobacilli). Gram-negative bacteria (Porphyromonas, Prevotella, Actinobacillus, and Fusobacterium) capable of growing in anaerobic environments are responsible for periodontal diseases. Due to the high prevalence of oral diseases, negative effects associated with the use of antimicrobial agents and increased antibiotic resistance in oral pathogens, suitable alternative methods (effective, economical and safe) to suppress microbes disturbing oral health need to be adopted. Side effects associated with the chemical antimicrobial agents are vomiting, diarrhea and tooth staining. Several researchers have studied the antimicrobial properties of plant extracts and phytochemicals and have used them as indigenous practices to control several infections. Therefore, phytochemicals extracted from plants can be suitable alternatives. This review focuses on the various phytochemical/plant extracts suppressing the growth of oral pathogens either by preventing their attachment to the surfaces or by preventing biofilm formation or other mechanisms.

Propolis mouthwashes efficacy in managing gingivitis and periodontitis: a systematic review of the latest findings

BACKGROUND AND OBJECTIVES

Gingivitis and periodontitis are common periodontal diseases that can significantly harm overall oral health, affecting the teeth and their supporting tissues, along with the surrounding anatomical structures, and if left untreated, leading to the total destruction of the alveolar bone and the connective tissues, tooth loss, and other more serious systemic health issues. Numerous studies have shown that propolis can help reduce gum inflammation, inhibit the growth of pathogenic bacteria, and promote tissue regeneration, but with varying degrees of success reported. For this reason, this comprehensive systematic review aims at finding out the truth concerning the efficacy of propolis mouthwashes in treating gingivitis and periodontitis, as its main objective.

DATA SOURCES

Research findings from 6 different databases: China National Knowledge Infrastructure (CNKI), PubMed®, Europe PMC, Cochrane Central Register of Controlled Trials (CENTRAL), BioMed Central, and Google Scholar, were retrieved and examined in addition to a manual search in the references lists.

STUDY SELECTION AND SYNTHESIS

The PICOS framework was used to select and exclude studies. The focus was on clinical randomized controlled trials (RCTs) that examined the effectiveness of propolis-containing mouthwashes in comparison with propolis-free ones for the treatment of gingivitis and periodontitis, employing related periodontal indices. Animal studies, microbiological studies, in-vitro studies, retrospective studies, case-control studies, cohorts, case reports, case series, reviews, letters, editorials, meta-analyses, and non-clinical randomized controlled trials (non-RCTs), all were excluded. A meta-analysis was not performed and data were only studied qualitatively due to the obvious heterogeneity amongst the studies. Data from the selected studies were extracted, and then the revised Cochrane's risk of bias tool (RoB 2.0) was utilised by two of the authors, independently, to evaluate the risk of bias in each study.

RESULTS

At first, 151 results were reached, but then after removing duplicates, 99 records remained, and were later screened, assessed, and studied in full details based on the set PICOS criteria. Out of these 99 articles, ten studies were included in this systematic review, encompassing a total of 453 patients with an age range of (13-70) years old. Propolis mouthwashes with different protocols of application were the intervention whereas placebo or the rest of the tested mouthwashes such as, chlorhexidine, sodium fluoride with cetylpyridinium chloride, sterile distilled water, hydrogen peroxide, were the ones to which propolis mouthwashes were compared. Treatment duration extended from 14 days to 3 months and the follow-up period differed from 14 days to 3 months. In general, propolis mouthwashes decreased plaque accumulations and gingival inflammation in gingivitis patients based on the employed indices. On the other hand, the aforementioned tested mouthwashes other than propolis were deemed equally effective or even superior to propolis in some studies. As an overall assessment for the risk of bias, four studies were assigned as having a low risk of bias. Two studies were deemed to have some concerns, while four studies were identified as having a high risk of bias.

CONCLUSIONS

Despite the fact that propolis has shown positive effects in terms of controlling gingival and periodontal inflammation especially when used with mechanical methods, studies lack certainty and their power of evidence is low with no agreed gold standards. These conclusions come, for sure, within the limitations of this review, like having substantial variability amongst the included studies and the presence of studies with a high risk of bias. The findings demonstrate that propolis-based mouthwashes showed promising clinical outcomes in reducing plaque and gingival inflammation. However, it is highly recommended to conduct more rigorous trials with patient-reported outcome measures, extended follow-up periods, larger samples sizes, better-designed methodologies, typified propolis use, and with the implementation of similar indices in order to obtain more reliable, conclusive, and generalisable results.

PROSPERO REGISTRATION NUMBER

CRD42024524523.

Potential effects of prebiotic fibers on dental caries: a systematic review

Certain dietary fibers exhibit prebiotic effects on gut microbiota, but their influence on oral health remains unclear. This study conducted a systematic review across four databases to examine the potential effects of dietary fibers on dental caries. Data selection and extraction were conducted independently and in duplicate. From 962 found titles, twenty studies were included, of which 13 were in vitro. The substances identified as prebiotics included fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), inulin, pectin, raffinose, polydextrose, sialyllactose, and short-chain fatty acids. Outcomes were assessed at biofilm (n = 14), saliva (n = 5), and tooth (n = 1) levels, with only six studies evaluating pH changes. Fifteen studies (75%) reported potential benefits, primarily attributed to the capacity of prebiotic fibers to limit the growth or adhesion of bacteria. Only two studies (10%) reported an increase in pH. Overall, the quality of the evidence was judged as moderate. In conclusion, certain dietary fibers may help limit caries development by modulating biofilm and pH levels. However, further clinical studies are needed to confirm the protective role of dietary fibers in dental caries. © 2025 Society of Chemical Industry.

Exploring the Influence of Oral and Gut Microbiota on Ulcerative Mucositis: A Pilot Cohort Study

AIM

Comparing oral and gut microbiome profiles between patients with and without ulcerative mucositis during allogeneic stem cell transplantation (aSCT).

MATERIALS AND METHODS

Specimens from oral mucosa, saliva, and stool were collected pre-(T0) and post- (T0 +28d ± 14d) aSCT (T1). Microbiome structure differences were analyzed by 16S-rRNA-gene sequencing, and associations to patients' clinical characteristics were investigated.

RESULTS

Ten of 25 included patients developed ulcerations. The α-diversity decreased between T0 and T1, independent of ulcerations. PERMANOVA revealed differences in beta diversity between T1 stool samples from patients with and without ulcerations. At T1, saliva samples of patients with ulcerations showed an increase of Mycoplasma salvarius, while commensals decreased in saliva and mucosal swabs. The gut microbiome of both groups showed an overabundance of Enterococcus spp., associated with inflammatory conditions. Salival α-diversity of older and overweight patients decreased slower, whereas in mucosal swabs mucositis or impaired renal function was associated with a higher decline. Female gender and history of periodontitis were associated with increased stool microbiome changes, while self-reported probiotics intake was related to reduced changes.

CONCLUSIONS

Ulcerations appeared in 40% of the patients. Distinct microbial changes, including increased abundance of Mycoplasma salivarius in saliva and decreased abundance of commensals, marked those with ulcerations.

TRIAL REGISTRATION

The study was registered in the German Register for Clinical Studies (DRKS00032882).

The oral microbial odyssey influencing chronic metabolic disease

INTRODUCTION

Since the oral cavity is the gateway to the gut, oral microbes likely hold the potential to influence metabolic disease by affecting the gut microbiota.

METHOD

A thorough review of literature has been performed to link the alterations in oral microbiota with chronic metabolic disease by influencing the gut microbiota.

RESULT

A strong correlation exists between abnormalities in oral microbiota and several systemic disorders, such as cardiovascular disease, diabetes, and obesity, which likely initially manifest as oral diseases. Ensuring adequate oral hygiene practices and cultivating diverse oral microflora are crucial for the preservation of general well-being. Oral bacteria have the ability to establish and endure in the gastrointestinal tract, leading to the development of prolonged inflammation and activation of the immune system. Oral microbe-associated prophylactic strategies could be beneficial in mitigating metabolic diseases.

CONCLUSION

Oral microbiota can have a profound impact on the gut microbiota and influence the pathogenesis of metabolic diseases.

[Research Progress on Drug Intervention to Inhibit Dental Plaque Biofilm Formation by Streptococcus mutans Based on the Concept of Ecological Prevention of Dental Caries]

Dental caries is the local destruction of hard tooth tissue caused by acidic byproducts generated by cariogenic bacteria, primarily Streptococcus mutans, which ferment free sugars in the presence of host factors, dietary components, and environmental conditions. A main feature of dental caries is the formation of dental plaque biofilm, which significantly improves the resistance of bacteria to drugs and host immunity. Traditional anti-caries drugs mainly exert anti-biofilm functions indirectly through antibacterial activities. However, they tend to interfere with the symbiotic microbiota while inhibiting cariogenic bacteria, which may cause imbalance within the oral microbial system. With increasing attention paid to the homeostasis of oral microbiota, new types of anti-caries drugs have been developed, such as natural extracts, artificially synthesized small molecules, and oligonucleotides. They act on key targets to inhibit the formation of biofilm substrates or regulate the interactions between oral microorganisms, thereby efficiently inhibiting biofilm formation. These drugs do not have bactericidal effects. Nevertheless, they exert indirect antimicrobial effects by interfering with biofilm substrate formation or microbial interactions. The optimization of delivery carriers, combination drug therapy, and biomimetic design further enhance the efficacy of these new types of anti-caries drugs. This article provides a review of the prevention and treatment principles and key targets of dental plaque biofilm. We also discussed the types, mechanisms of action, and development trends of relevant drugs.

Could the Arginine-Fluoride Association Have a Real Impact on Caries Prevention?

In the context of preventive therapy, fluoride has allowed the reduction of the incidence and prevalence of caries. The establishment of the protective role of arginine in the neutralization of plaque acids has led to the development of new arginine-fluorine associations to potentiate this preventive aspect. Studies have reported that this association could provide superior efficacy compared to fluoride alone. A synergistic effect that could be potential and thus represent a promising ecological approach for caries prevention. However, confirmation of the effective efficacy of the arginine-fluoride association requires additional clinical studies to be carried out before establishing recommendations.

Candida species in periodontitis: A new villain or a new target?

OBJECTIVES

Recent research indicated that fungi might have a role in periodontitis alongside traditional periodontal pathogens. This state-of-the-art narrative review explores current concepts on the involvement of Candida species in periodontitis, and suggests the potential for ecological management of this disease.

DATA, SOURCES AND STUDY SELECTION

A literature search was conducted for a narrative review on Web of Science, PubMed, Medline and Scopus about periodontitis associated with Candida species. Published articles, including case reports, case series, observational and interventional clinical trials, and critical appraisals of the literature were retrieved and reviewed.

CONCLUSIONS

Several factors predispose individuals to periodontitis associated with Candida species. These include systemic diseases that lead to immunosuppression and oral environment changes such as cigarette smoking. While a consistent significant increase in the detection rate of Candida species in patients with periodontitis has not been universally observed, there is evidence linking Candida species to the severity of periodontitis and their potential to worsen the condition. Candida species may participate in the development of periodontitis in various ways, including cross-kingdom interactions with periodontal pathogens, changes in the local or systemic environment favoring the virulence of Candida species, and interactions between Candida-bacteria and host immunity.

CLINICAL SIGNIFICANCE

Mechanical plaque control is the most common treatment for periodontitis, but its effectiveness may be limited, particularly when dealing with systemic risk factors. Understanding the specific role of Candida in periodontitis illuminates innovative approaches for managing the ecological balance in periodontal health.

How well do antimicrobial mouth rinses prevent dysbiosis in an in vitro periodontitis biofilm model?

BACKGROUND

Periodontal diseases are associated with dysbiosis in the oral microbial communities. Managing oral biofilms is therefore key for preventing these diseases. Management protocols often include over-the-counter antimicrobial mouth rinses, which lack data on their effects on the oral microbiome's ecology, bacterial composition, metabolic activity, and dysbiosis resilience. This study examined the efficacy of antimicrobial mouth rinses to halt dysbiosis in in vitro oral biofilms under periodontitis-simulating conditions.

METHODS

Multispecies oral biofilms were grown on hydroxyapatite discs (HADs) and rinsed daily with one of six mouth rinses. Positive and negative controls were included. After three rinses, biofilms were analyzed with viability quantitative polymerase chain reaction and visualized using scanning electron microscopy. Supernatants of rinsed biofilms were used for metabolic activity analysis. In addition, human oral keratinocytes were exposed to rinsed biofilms to assess their inflammatory response. All outputs were analyzed for correlation using Spearman coefficient.

RESULTS

Product-related changes were observed in the rinsed biofilms. Three of the six tested mouth rinses could significantly prevent dysbiosis with ≥30% reduction in pathobiont abundance relative to the control. These biofilms had lower metabolic activity, and the exposed human oral keratinocyte produced less interleukin-8. Interleukin-8 production correlated to both pathobiont quantity and the metabolic activity of the biofilms.

CONCLUSION

Some mouth rinses could support biofilm resilience and stop dysbiosis evolution in the biofilm model, with a clear product-related effect. Such mouth rinses can be considered for patients under maintenance/supportive periodontal therapy to prevent/delay disease recurrence. Others are more useful for different periodontal therapy stages.

Cannabis use, oral dysbiosis, and neurological disorders

Cannabis (marijuana) is a leafy plant that has medical, recreational, and other uses. Cannabis is socially accepted and widely used throughout the United States. Though cannabis use is increasingly gaining popularity, studies detail the deleterious effects of chronic cannabis smoking on mental health, as well as the immunosuppressive properties of cannabinoids. Additionally, oral dysbiosis induced by cannabis smoking serves as a novel catalyst for neurological abnormalities, potentially possible through microbial translocation via the oral-brain axis. This review summarizes the effects and link of smoking cannabis on neurological abnormalities, immunity, and oral microbiome.

Potential of microbial-derived biosurfactants for oral applications-a systematic review

BACKGROUND

Biosurfactants are amphiphilic compounds produced by various microorganisms. Current research evaluates diverse types of biosurfactants against a range of oral pathogens.

OBJECTIVES

This systematic review aims to explore the potential of microbial-derived biosurfactants for oral applications.

METHODOLOGY

A systematic literature search was performed utilizing PubMed-MEDLINE, Scopus, and Web of Science databases with designated keywords. The results were registered in the PROSPERO database and conducted following the PRISMA checklist. Criteria for eligibility, guided by the PICOS framework, were established for both inclusion and exclusion criteria. The QUIN tool was used to assess the bias risk for in vitro dentistry studies.

RESULTS

Among the initial 357 findings, ten studies were selected for further analysis. The outcomes of this systematic review reveal that both crude and purified forms of biosurfactants exhibit antimicrobial and antibiofilm properties against various oral pathogens. Noteworthy applications of biosurfactants in oral products include mouthwash, toothpaste, and implant coating.

CONCLUSION

Biosurfactants have garnered considerable interest and demonstrated their potential for application in oral health. This is attributed to their surface-active properties, antiadhesive activity, biodegradability, and antimicrobial effectiveness against a variety of oral microorganisms, including bacteria and fungi.

Dysbiosis linking periodontal disease and oral squamous cell carcinoma-A brief narrative review

An association between periodontal disease and oral squamous cell carcinoma (OSCC) has been recognized. However, there is no causal relationship between the two. The polymicrobial etiology of periodontal disease is confirmed, and so are the proven etiological factors for OSCC. Inflammation lies at the core of periodontal pathogenesis induced by the putative microbes. OSCC has inflammatory overtures in its pathobiology. Bacterial species involved in periodontal disease have been extensively documented and validated. The microbial profile in OSCC has been explored with no specific conclusions. The scientific reasoning to link a common microbial signature that connects periodontal disease to OSCC has led to many studies but has not provided conclusive evidence. Therefore, it would be beneficial to know the status of any plausible microbiota having a similarity in periodontal disease and OSCC. This brief review attempted to clarify the existence of a dysbiotic "fingerprint" that may link these two diseases. The review examined the literature with a focused objective of identifying periodontal microbial profiles in OSCC that could provide insights into pathogen commonality. The review concluded that there is great diversity in microbial association, but important bacterial species that correlate with periodontal disease and OSCC are forthcoming.

Sucrose rinse modulates the salivary behavior of carbonic anhydrase VI and its buffering capacity: a longitudinal study in 4 to 6.5-year-old children

Background

Carbonic anhydrase VI (CA VI) is crucial in regulating oral pH and predicting susceptibility to dental caries. The hypothesis posits that caries activity may alter the CA VI function, diminishing its capacity to regulate pH effectively and potentially exacerbating cariogenic challenges. This 1-year cohort study sought to investigate the enzymatic activity of salivary CA VI and buffering capacity following a 20% sucrose rinse in 4 to 6.5-year-old children.

Method

This research involved 46 volunteers categorized into three groups based on their caries status after follow-up: caries-free (CFee), arrested caries (CArrested), and caries active (CActive). Children underwent visible biofilm examination and saliva collection for salivary flow rate, buffering capacity, and CA VI analyses before and after a 20% sucrose rinse.

Results

A reduction in the buffering capacity was observed after sucrose rinse in all groups. The CA VI activity decreased significantly in CFee and CArrested groups after sucrose rinse, although it did not change in the CActive group. An improvement in the buffering capacity and salivary flow rate was found at follow-up when compared with the baseline. After 1-year follow-up, buffering capacity and salivary flow rate increased in all groups, whilst the CA VI activity reduced only in CFree and CArrested children.

Conclusion

Sucrose rinse universally reduces the salivary buffering capacity, while caries activity may disrupt CA VI activity response during a cariogenic challenge. After a year, increased salivary flow enhances buffering capacity but not CA VI activity in caries-active children.

Prevention and management of dental erosion and decay

The 2017 Global Disease Study revealed 2.3 billion untreated cavities and 139 million other oral conditions like dental erosion. Modern treatments prioritise controlling etiological factors and preventing related diseases. This Editorial invites researchers to contribute to the collection, 'Prevention and management of dental erosion and decay'.

Effects of glucose and lactate on Streptococcus mutans abundance in a novel multispecies oral biofilm model

The oral microbiome plays an important role in protecting oral health. Here, we established a controlled mixed-species in vitro biofilm model and used it to assess the impact of glucose and lactate on the ability of Streptococcus mutans, an acidogenic and aciduric species, to compete with commensal oral bacteria. A chemically defined medium was developed that supported the growth of S. mutans and four common early colonizers of dental plaque: Streptococcus gordonii, Actinomyces oris, Neisseria subflava, and Veillonella parvula. Biofilms containing the early colonizers were developed in a continuous flow bioreactor, exposed to S. mutans, and incubated for up to 7 days. The abundance of bacteria was estimated by quantitative polymerase chain reaction (qPCR). At high glucose and high lactate, the pH in bulk fluid rapidly decreased to approximately 5.2, and S. mutans outgrew other species in biofilms. In low glucose and high lactate, the pH remained above 5.5, and V. parvula was the most abundant species in biofilms. By contrast, in low glucose and low lactate, the pH remained above 6.0 throughout the experiment, and the microbial community in biofilms was relatively balanced. Fluorescence in situ hybridization confirmed that all species were present in the biofilm and the majority of cells were viable using live/dead staining. These data demonstrate that carbon source concentration is critical for microbial homeostasis in model oral biofilms. Furthermore, we established an experimental system that can support the development of computational models to predict transitions to microbial dysbiosis based on metabolic interactions.IMPORTANCEWe developed a controlled (by removing host factor) dynamic system metabolically representative of early colonization of Streptococcus mutans not measurable in vivo. Hypotheses on factors influencing S. mutans colonization, such as community composition and inoculation sequence and the effect of metabolite concentrations, can be tested and used to predict the effect of interventions such as dietary modifications or the use of toothpaste or mouthwash on S. mutans colonization. The defined in vitro model (species and medium) can be simulated in an in silico model to explore more of the parameter space.

Using formalin fixed paraffin embedded tissue to characterize the microbiota in p16-positive and p16-negative tongue squamous cell carcinoma: a pilot study

BACKGROUND

Tongue squamous cell carcinoma (TSCC) is the most common oral cavity cancer, and p16 immunohistochemistry is an exact and available tool in the prognostic and predictive characterization of squamous cell cancers in the head and neck. Microorganisms have a close relationship with the development of TSCC. However, the association between oral bacteria and p16 status has not been well defined in the case of TSCC. Compared with traditional clinical microbial collection methods, formalin-fixed paraffin-embedded (FFPE) tissue samples have several advantages.

METHODS

To compare the microbiota compositions between p16-positive and p16-negative patients with TSCC, we performed a small pilot study of microbiological studies of TSCC by paraffin tissue. DNA from FFPE tissue blocks were extracted and microbiomes were profiled by sequencing the 16 S-rRNA-encoding gene (V1-V2/V3-V4/V4 regions). Alterations in the functional potential of the microbiome were predicted using PICRUSt, Tax4Fun, and BugBase.

RESULTS

A total of 60 patients with TSCC were enrolled in the study, however, some challenges associated with DNA damage in FFPE tissues existed, and only 27 (15 p16-positive and 12 p16-negative) passed DNA quality control. Nevertheless, we have tentatively found some meaningful results. The p16 status is associated with microbiota diversity, which is significantly increased in p16-positive patients compared with p16-negative patients. Desulfobacteria, Limnochordia, Phycisphaerae, Anaerolineae, Saccharimonadia and Kapabacteria had higher abundances among participants with p16-positive. Moreover, functional prediction revealed that the increase of these bacteria may enhance viral carcinogenesis in p16-positive TSCC.

CONCLUSIONS

Bacterial profiles showed a significant difference between p16-positive TSCC and p16-negative TSCC. These findings may provide insights into the relationship between p16 status and the microbial taxa in TSCC, and these bacteria may provide new clues for developing therapeutic targets for TSCC.

How probiotics, prebiotics, synbiotics, and postbiotics prevent dental caries: an oral microbiota perspective

Dental caries, a highly prevalent oral disease, impacts a significant portion of the global population. Conventional approaches that indiscriminately eradicate microbes disrupt the natural equilibrium of the oral microbiota. In contrast, biointervention strategies aim to restore this balance by introducing beneficial microorganisms or inhibiting cariogenic ones. Over the past three decades, microbial preparations have garnered considerable attention in dental research for the prevention and treatment of dental caries. However, unlike related pathologies in the gastrointestinal, vaginal, and respiratory tracts, dental caries occurs on hard tissues such as tooth enamel and is closely associated with localized acid overproduction facilitated by cariogenic biofilms. Therefore, it is insufficient to rely solely on previous mechanisms to delineate the role of microbial preparations in the oral cavity. A more comprehensive perspective should involve considering the concepts of cariogenic biofilms. This review elucidates the latest research progress, mechanisms of action, challenges, and future research directions regarding probiotics, prebiotics, synbiotics, and postbiotics for the prevention and treatment of dental caries, taking into account the unique pathogenic mechanisms of dental caries. With an enhanced understanding of oral microbiota, personalized microbial therapy will emerge as a critical future research trend.

Manipulating the diseased oral microbiome: the power of probiotics and prebiotics

Dental caries and periodontal disease are amongst the most prevalent global disorders. Their aetiology is rooted in microbial activity within the oral cavity, through the generation of detrimental metabolites and the instigation of potentially adverse host immune responses. Due to the increasing threat of antimicrobial resistance, alternative approaches to readdress the balance are necessary. Advances in sequencing technologies have established relationships between disease and oral dysbiosis, and commercial enterprises seek to identify probiotic and prebiotic formulations to tackle preventable oral disorders through colonisation with, or promotion of, beneficial microbes. It is the metabolic characteristics and immunomodulatory capabilities of resident species which underlie health status. Research emphasis on the metabolic environment of the oral cavity has elucidated relationships between commensal and pathogenic organisms, for example, the sequential metabolism of fermentable carbohydrates deemed central to acid production in cariogenicity. Therefore, a focus on the preservation of an ecological homeostasis in the oral environment may be the most appropriate approach to health conservation. In this review we discuss an ecological approach to the maintenance of a healthy oral environment and debate the potential use of probiotic and prebiotic supplementation, specifically targeted at sustaining oral niches to preserve the delicately balanced microbiome.

Exploring the Role of IL-17A in Oral Dysbiosis-Associated Periodontitis and Its Correlation with Systemic Inflammatory Disease

Oral microbiota play a pivotal role in maintaining homeostasis, safeguarding the oral cavity, and preventing the onset of disease. Oral dysbiosis has the potential to trigger pro-inflammatory effects and immune dysregulation, which can have a negative impact on systemic health. It is regarded as a key etiological factor for periodontitis. The emergence and persistence of oral dysbiosis have been demonstrated to mediate inflammatory pathology locally and at distant sites. The heightened inflammation observed in oral dysbiosis is dependent upon the secretion of interleukin-17A (IL-17A) by various innate and adaptive immune cells. IL-17A has been found to play a significant role in host defense mechanisms by inducing antibacterial peptides, recruiting neutrophils, and promoting local inflammation via cytokines and chemokines. This review seeks to present the current knowledge on oral dysbiosis and its prevention, as well as the underlying role of IL-17A in periodontitis induced by oral dysbiosis and its impact on systemic inflammatory disease.

Mutanase from Trichoderma harzianum inductively Produced by Mutan: Short-Term Treatment to Degrade Mature Streptococcus mutans Biofilm

This study aimed to evaluate the disruptive effect of fungal mutanase against cariogenic biofilm after short-term treatment. For that, mature Streptococcus mutans biofilms (n = 9) were exposed to active or inactivated enzymes produced by Trichoderma harzianum for 1 min, two times per day. Biofilms were analyzed by amount of matrix water-insoluble polysaccharides, bacterial viability, acidogenicity, and morphology by scanning electron microscopy (SEM). The group treated with active enzymes (AE) had a significantly lower amount of insoluble polysaccharides (893.30 ± 293.69) when compared to the negative control group (NaCl, 2192.59 ± 361.96), yet no significant difference was found when comparing to the positive control group (CHX, 436.82 ± 151.07). Also, there was no significant effect on bacteria metabolism and viability (P-value < 0.05). Data generated by the quantitative analysis were confirmed through scanning electron microscopy images. Thus, fungal mutanase degraded the biofilm after a short-term treatment without interfering with bacterial viability and metabolism. Such findings offer insight to the development of routine oral care products containing this input.

Lactobacillus acidophilus impairs the establishment of pathogens in a subgingival multispecies biofilm

The present study evaluated the antibiofilm effects of Lactobacillus acidophilus within a subgingival multispecies biofilm. Lactobacillus acidophilus (La5) at 1 × 102, 1 × 104, and 1 × 106 were included at the beginning of biofilm formation, which lasted 7 days. The biofilms comprised 33 periodontitis-related bacterial species and the Calgary Biofilm device was used. At the end, DNA-DNA hybridization (checkerboard) was performed. A Kruskal-Wallis test followed by a Dunn post hoc test were performed (p ≤ 0.05). La5 at 1 × 104 and 1 × 106 reduced the total counts of biofilm and the proportions of red and green complexes when compared to the control biofilm without La5 (p ≤ 0.05). La5 at 1 × 104 increased the proportions of Actinomyces complex compared to the controls (p ≤ 0.05). Both La5 at 1 × 104 and 1 × 106 decreased levels of 20 and 14 distinct species, respectively, including Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum polymorphum, and Parvimonas micra compared to the control (p ≤ 0.05). Only La5 at 1 × 104 reduced the levels of Tannerella forsythia, Fusobacterium periodonticum, and Aggregatibacter actinomycetencomytans compared to the control (p ≤ 0.05). L. acidophilus inhibited establishing periodontic pathogens from red complex such as P. gingivalis and T. forsythia in a subgingival multispecies biofilm.

Antimicrobial Efficiency of Pistacia lentiscus L. Derivates against Oral Biofilm-Associated Diseases-A Narrative Review

Pistacia lentiscus L. (PlL) has been used for centuries in traditional medicine. The richness in antimicrobial biomolecules of Pll derivates can represent an alternative to chemically formulated agents used against oral infections. This review summarizes the knowledge on the antimicrobial activity of PlL essential oil (EO), extracts, and mastic resin against microorganisms being of relevance in oral biofilm-associated diseases. Results demonstrated that the potential of PlL polyphenol extracts has led to increasing scientific interest. In fact, the extracts are a significantly more effective agent than the other PlL derivates. The positive findings regarding the inhibition of periodontal pathogens and C. albicans, together with the antioxidant activity and the reduction of the inflammatory responses, suggest the use of the extracts in the prevention and/or reversal of intraoral dysbiosis. Toothpaste, mouthwashes, and local delivery devices could be effective in the clinical management of these oral diseases.

Positive feedback loop between dietary nitrate intake and oral health

Nitrate was once thought to be an inert end-product of endothelial-derived nitric oxide (NO) heme oxidation; however, this view has been radically revised over the past few decades. Following the clarification of the nitrate-nitrite-NO pathway, accumulated evidence has shown that nitrate derived from the diet is a supplementary source of endogenous NO generation, playing important roles in a variety of pathological and physiological conditions. However, the beneficial effects of nitrate are closely related with oral health, and oral dysfunction has an adverse effect on nitrate metabolism and further impacts overall systemic health. Moreover, an interesting positive feedback loop has been identified between dietary nitrate intake and oral health. Dietary nitrate's beneficial effect on oral health may further improve its bioavailability and promote overall systemic well-being. This review aims to provide a detailed description of the functions of dietary nitrate, with an emphasis on the key role oral health plays in nitrate bioavailability. This review also provides recommendations for a new paradigm that includes nitrate therapy in the treatment of oral diseases.

The efficacy of mouthwashes on oral microorganisms and gingivitis in patients undergoing orthodontic treatment: a systematic review and meta-analysis

BACKGROUND

Mouthwashes were convenient adjuncts to mechanical cleaning procedures. This review aimed to evaluate the efficacy of mouthwashes on oral microorganisms and gingivitis in orthodontic patients.

METHODS

By April 16, 2022, multiple databases and grey literature were searched based on the PICOS strategy. Randomized controlled trials in orthodontic patients evaluating the efficacy of mouthwashes with at least one microbial parameter and/or plaque- and/or gingival inflammation-related index were included. Relevant data were extracted, and the risk of bias was evaluated using Cochrane's tool. Individual mean and standard deviation of the outcomes in mouthwashes and placebos/blank controls were pooled to estimate the weighted mean differences (WMDs) and 95% confidence intervals (95%CIs). Sensitivity analysis, and certainty of evidence were evaluated.

RESULTS

Of 1684 articles, 32 studies satisfied the eligibility criteria, and nine were included for meta-analysis. Missing outcome data was the primary source of bias. Compared to blank controls, the short-term application of fluoride mouthwashes significantly reduced the colony counts of Mutans streptococci (MS), while the long-term application may not be effective. Compared to placebos or blank controls, Chlorhexidine mouthwashes significantly reduced the colony counts of multiple microorganisms in the short-term. Compared to placebos or blank controls, herbal mouthwashes showed the inhibitory effect of MS in the short-term, with some results lacking statistical significance. After meta-analysis, significant lower plaque- and gingival inflammation-related indexes were observed in the Chlorhexidine mouthwashes groups [Gingival Index: WMD = -0.45, 95%CI = -0.70 to -0.20 (placebos as control); WMD = -0.54, 95%CI = -0.96 to -0.13 (blank controls); Plaque Index: WMD = -0.70, 95%CI = -1.12 to -0.27 (blank controls)]. Significant lower gingival inflammation-related indexes were observed in the herbal mouthwashes groups [Gingival Index: WMD = -0.20, 95%CI = -0.32 to -0.09 (blank controls)].

CONCLUSIONS

The short-term application of fluoride mouthwashes may reduce the colony counts of cariogenic bacteria, but the long-term effect is not evident. Chlorhexidine may reduce the colony counts of multiple microorganisms in the short-term. Short-term application Chlorhexidine and herbal mouthwashes may effectively reduce plaque- and gingival inflammation-related indexes. However, the risk of bias, inconsistency, and imprecision in the included studies may reduce the certainty of the evidence.

Evaluation of the Oral Bacterial Genome and Metabolites in Patients with Wolfram Syndrome

In Wolfram syndrome (WFS), due to the loss of wolframin function, there is increased ER stress and, as a result, progressive neurodegenerative disorders, accompanied by insulin-dependent diabetes. The aim of the study was to evaluate the oral microbiome and metabolome in WFS patients compared with patients with type 1 diabetes mellitus (T1DM) and controls. The buccal and gingival samples were collected from 12 WFS patients, 29 HbA1c-matched T1DM patients (p = 0.23), and 17 healthy individuals matched by age (p = 0.09) and gender (p = 0.91). The abundance of oral microbiota components was obtained by Illumina sequencing the 16S rRNA gene, and metabolite levels were measured by gas chromatography–mass spectrometry. Streptococcus (22.2%), Veillonella (12.1%), and Haemophilus (10.8%) were the most common bacteria in the WFS patients, while comparisons between groups showed significantly higher abundance of Olsenella, Dialister, Staphylococcus, Campylobacter, and Actinomyces in the WFS group (p < 0.001). An ROC curve (AUC = 0.861) was constructed for the three metabolites that best discriminated WFS from T1DM and controls (acetic acid, benzoic acid, and lactic acid). Selected oral microorganisms and metabolites that distinguish WFS patients from T1DM patients and healthy individuals may suggest their possible role in modulating neurodegeneration and serve as potential biomarkers and indicators of future therapeutic strategies.

Ecological influence by colonization of fluoride-resistant Streptococcus mutans in oral biofilm

Background

Dental caries is one of the oldest and most common infections in humans. Improved oral hygiene practices and the presence of fluoride in dentifrices and mouth rinses have greatly reduced the prevalence of dental caries. However, increased fluoride resistance in microbial communities is concerning. Here, we studied the effect of fluoride-resistant Streptococcus mutans (S. mutans) on oral microbial ecology and compare it with wild-type S. mutans in vitro.

Methods

Biofilm was evaluated for its polysaccharide content, scanning electron microscopy (SEM) imaging, acid-producing ability, and related lactic dehydrogenase (LDH), arginine deiminase (ADS), and urease enzymatic activity determination. Fluorescence in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (qRT-PCR) were used to evaluate the S. mutans ratio within the biofilm. It was followed by 16S rRNA sequencing to define the oral microbial community.

Results

Fluoride-resistant S. mutans produced increased polysaccharides in presence of NaF (P < 0.05). The enzymatic activities related to both acid and base generation were less affected by the fluoride. In presence of 275 ppm NaF, the pH in the fluoride-resistant strain sample was lower than the wild type. We observed that with the biofilm development and accumulative fluoride concentration, the fluoride-resistant strain had positive relationships with other bacteria within the oral microbial community, which enhanced its colonization and survival. Compared to the wild type, fluoride-resistant strain significantly increased the diversity and difference of oral microbial community at the initial stage of biofilm formation (4 and 24 h) and at a low fluoride environment (0 and 275 ppm NaF) (P < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that fluoride-resistant strain enhanced the metabolic pathways and glucose transfer.

Conclusions

Fluoride-resistant S. mutans affected the microecological balance of oral biofilm and its cariogenic properties in vitro, indicating its negative impact on fluoride's caries prevention effect.

Incorporation of Nanomaterials in Glass Ionomer Cements-Recent Developments and Future Perspectives: A Narrative Review

Glass ionomer cements (GICs), restorative materials with commercial availability spanning over five decades, are widely applied due to their advantages (including bio-compatibility, fluoride release, or excellent bonding properties). However, GICs have shortcomings. Among the disadvantages limiting the application of GICs, the poor mechanical properties are the most significant. In order to enhance the mechanical or antimicrobial properties of these materials, the addition of nanomaterials represents a viable approach. The present paper aims to review the literature on the application of different types of nanomaterials for the enhancement of GICs' mechanical and antimicrobial properties, which could lead to several clinical benefits, including better physical properties and the prevention of tooth decay. After applying the described methodology, representative articles published in the time period 2011-present were selected and included in the final review, covering the modification of GICs with metallic nanoparticles (Cu, Ag), metallic and metalloid oxide nanoparticles (TiO₂, ZnO, MgO, Al₂O₃, ZrO₂, SiO₂), apatitic nanomaterials, and other nanomaterials or multi-component nanocomposites.

The Impact of Omega-3 Supplements on Non-Surgical Periodontal Therapy: A Systematic Review

AIM

This systematic review examined the additional effect of taking omega-3 supplements on periodontal therapy.

METHODS

The focused question was "What is the possible effect of omega-3 supplementation concomitant to non-surgical periodontal therapy on clinical periodontal parameters?" Databases Cochrane, Embase, Google Scholar, PubMed, and Web of Science (January-July 2021) were searched to identify appropriate studies. Randomized clinical trials (RCT) about non-surgical therapy with omega-3 supplementation, with at least 3 months of supplementation period were included. Cochrane risk of bias tool version 2 and Grading of Recommendations Assessment, Development, and Evaluation were used.

RESULTS

A total of 1556 studies were found, of which eight studies met the inclusion criteria. All eight studies evaluated periodontal probing depth and clinical attachment loss; plaque and gingival inflammation were evaluated in seven studies. High variety of omega-3 dosage, different study lengths, questionable results from periodontal therapy (including test and control groups), high risk of bias and moderate quality of evidence prevented a satisfactory conclusion regarding the benefits of omega-3 supplementation. The studies' high heterogeneity avoided meta-analysis.

CONCLUSION

Notwithstanding all limitations, the promising effects of omega-3 supplementation presented in two six-month studies encourage performing RCT with better-defined treatment protocols and greater methodological rigor.

Influence of Fluoride-Resistant Streptococcus mutans Within Antagonistic Dual-Species Biofilms Under Fluoride In Vitro

The widespread application of fluoride, an extremely effective caries prevention agent, induces the generation of fluoride-resistant strains of opportunistic cariogenic bacteria such as fluoride-resistant Streptococcus mutans (S. mutans). However, the influence of this fluoride-resistant strain on oral microecological homeostasis under fluoride remains unknown. In this study, an antagonistic dual-species biofilm model composed of S. mutans and Streptococcus sanguinis (S. sanguinis) was used to investigate the influence of fluoride-resistant S. mutans on dual-species biofilm formation and pre-formed biofilms under fluoride to further elucidate whether fluoride-resistant strains would influence the anti-caries effect of fluoride from the point of biofilm control. The ratio of bacteria within dual-species biofilms was investigated using quantitative real-time PCR and fluorescence in situ hybridization. Cristal violet staining, scanning electron microscopy imaging, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay were used to evaluate biofilm biomass, biofilm structure, and metabolic activity, respectively. Biofilm acidogenicity was determined using lactic acid and pH measurements. The anthrone method and exopolysaccharide (EPS) staining were used to study the EPS production of biofilms. We found that, in biofilm formation, fluoride-resistant S. mutans occupied an overwhelming advantage in dual-species biofilms under fluoride, thus showing more biofilm biomass, more robust biofilm structure, and stronger metabolic activity (except for 0.275 g/L sodium fluoride [NaF]), EPS production, and acidogenicity within dual-species biofilms. However, in pre-formed biofilms, the advantage of fluoride-resistant S. mutans could not be fully highlighted for biofilm formation. Therefore, fluoride-resistant S. mutans could influence the anti-caries effect of fluoride on antagonistic dual-species biofilm formation while being heavily discounted in pre-formed biofilms from the perspective of biofilm control.

Regulatory Effect of Irresistin-16 on Competitive Dual-Species Biofilms Composed of Streptococcus mutans and Streptococcus sanguinis

Based on the ecological plaque hypothesis, suppressing opportunistic pathogens within biofilms, rather than killing microbes indiscriminately, could be a biofilm control strategy for managing dental caries. The present study aimed to evaluate the effects of irresistin-16 (IRS-16) on competitive dual-species biofilms, which consisted of the conditional cariogenic agent Streptococcus mutans (S. mutans) and oral commensal bacteria Streptococcus sanguinis (S. sanguinis). Bacterial growth and biofilm formation were monitored using growth curve and crystal violet staining, respectively. The microbial proportion was determined using fluorescence in situ hybridization. A 2, 5-diphenyltetrazolium bromide assay was used to measure the metabolic activity of biofilms. Bacterial/extracellular polysaccharide (EPS) dyeing, together with water-insoluble EPS measurements, were used to estimate EPS synthesis. A lactic acid assay was performed to detect lactic acid generation in biofilms. The cytotoxicity of IRS-16 was evaluated in mouse fibroblast L929 cells using a live/dead cell viability assay and cell counting kit-8 assay. Our results showed that IRS-16 exhibited selective anti-biofilm activity, leading to a remarkable survival disadvantage of S. mutans within competitive dual-species biofilms. In addition, the metabolic activity, EPS synthesis, and acid generation of dual-species biofilms were significantly reduced by IRS-16. Moreover, IRS-16 showed minimal cytotoxicity against mouse fibroblast L929 cells. In conclusion, IRS-16 exhibited remarkable regulatory effects on dual-species biofilms composed of S. mutans and S. sanguinis with low cytotoxicity, suggesting that it may have potential for use in caries management through ecological biofilm control.

Mesenchymal Stromal/Stem Cells-Derived Exosomes as an Antimicrobial Weapon for Orodental Infections

The oral cavity as the second most various microbial community in the body contains a broad spectrum of microorganisms which are known as the oral microbiome. The oral microbiome includes different types of microbes such as bacteria, fungi, viruses, and protozoa. Numerous factors can affect the equilibrium of the oral microbiome community which can eventually lead to orodental infectious diseases. Periodontitis, dental caries, oral leukoplakia, oral squamous cell carcinoma are some multifactorial infectious diseases in the oral cavity. In defending against infection, the immune system has an essential role. Depending on the speed and specificity of the reaction, immunity is divided into two different types which are named the innate and the adaptive responses but also there is much interaction between them. In these responses, different types of immune cells are present and recent evidence demonstrates that these cell types both within the innate and adaptive immune systems are capable of secreting some extracellular vesicles named exosomes which are involved in the response to infection. Exosomes are 30-150 nm lipid bilayer vesicles that consist of variant molecules, including proteins, lipids, and genetic materials and they have been associated with cell-to-cell communications. However, some kinds of exosomes can be effective on the pathogenicity of various microorganisms and promoting infections, and some other ones have antimicrobial and anti-infective functions in microbial diseases. These discrepancies in performance are due to the origin of the exosome. Exosomes can modulate the innate and specific immune responses of host cells by participating in antigen presentation for activation of immune cells and stimulating the release of inflammatory factors and the expression of immune molecules. Also, mesenchymal stromal/stem cells (MSCs)-derived exosomes participate in immunomodulation by different mechanisms. Ease of expansion and immunotherapeutic capabilities of MSCs, develop their applications in hundreds of clinical trials. Recently, it has been shown that cell-free therapies, like exosome therapies, by having more advantages than previous treatment methods are emerging as a promising strategy for the treatment of several diseases, in particular inflammatory conditions. In orodental infectious disease, exosomes can also play an important role by modulating immunoinflammatory responses. Therefore, MSCs-derived exosomes may have potential therapeutic effects to be a choice for controlling and treatment of orodental infectious diseases.

A Two-Year Longitudinal Study of the Effectiveness of the CRT® Bacteria Test in Evaluating Caries Risk in Three-Year-Old Children

Objective

To study the correlation between the level of infection with Streptococcus mutans (SM) and lactobacilli (LB) in saliva with existing status and the development of primary dental caries in 3-year-old children and to evaluate the results of CRT^® bacteria as a Caries Risk Test.

Methods

A total of 140 3-year-old children were selected for the study. Oral examination was conducted and the levels of infection with SM and LB in saliva were measured using a CRT^® bacteria test. Oral reexamination was conducted after two years. The prevalence rate of caries, the decayed-missing-filled tooth (dmft) and decayed-missing-filled surface (dmfs) indices, and Caries Severity Index (CSI) were calculated at the start and end of the two years. The indices were statistically analyzed.

Results

The caries prevalence rate, dmft, dmfs, and CSI increased with increasing levels of CRT-SM and CRT-LB at the start and end of the two years; the increases in dmft, dmfs, and CSI over the period were consistent with the increases in CRT-SM and CRT-LB levels, with all differences being highly statistically significant. The increase in caries prevalence rate over the two years was not statistically different for different CRT-SM and CRT-LB levels. CRT-SM and CRT-LB levels were highly positively correlated with dmft, dmfs, CSI and their increases over the two years. Levels of infection with oral SM and LB were found to be independent risk factors for primary dental caries, respectively. For an SM concentration in saliva of ≥10⁴ CFU/mL and an LB concentration of <10⁴ CFU/mL, the risk of caries increased by approximately 2.8-fold. When the concentration of LB in saliva was ≥10⁴ CFU/mL and that of SM <10⁴ CFU/mL, the risk of caries increased by approximately 3.9-fold. When the concentration of both SM and LB was ≥10⁴ CFU/mL, the risk increased by approximately 10.9-fold.

Conclusions

Significant positive correlations were found between the level of infection with oral SM and LB and existing oral decay status and the trend in the development of primary dental caries. Infection with SM and LB significantly increased the risk of caries in primary teeth. The CRT^® bacteria is a simple, convenient, reliable, and effective Caries Risk Test.

Nonrestorative Management of Dental Caries

The World Dental Federation (FDI) policy statement in 2016 advocated evidence-based caries-control measures for managing dental caries. The caries management philosophy has shifted from the traditional surgical manners to minimal intervention dentistry. Minimal intervention dentistry aims to extend the longevity of natural teeth. It places the nonrestorative approaches as a priority. The nonrestorative approaches for caries management aim to tackle the etiological factors of dental caries. Caries can be prevented or reversed by restricting the sugar intake and its frequency in the diet, improving oral hygiene practices, and using fluoride toothpaste. This article aims to present strategies for the nonrestorative management of dental caries, which are divided into four components to address the different etiological factors of dental caries. The first component is controlling dental plaque. Strategies for plaque control include oral hygiene instruction, motivational interviewing, mechanical plaque control, and chemical plaque control. The second component for nonrestorative management is reducing the risk of caries by identifying caries risk factors and protective factors, assessing personal caries risk, and customizing a treatment plan. Evidence-based measures for caries prevention include using fluoride, and dental sealants should be provided. The third component includes topical treatment to remineralise early carious lesions. The last component is long-term follow-up. Appropriate strategy adoption for the nonrestorative management of dental caries prolongs the life span of the teeth and sustains the good oral health of patients.

Active Bacteria in Carious Dentin of Mandibular Molars with Different Pulp Conditions: An In Vivo Study

INTRODUCTION

This study evaluated the relative abundance and ribosomal activity of selected bacteria in carious dentin of teeth with different pulp conditions.

METHODS

Thirty healthy patients with class I occlusal caries in molars were categorized into 3 groups based on the pulp diagnosis: normal pulp (NP, n = 10) with caries extending less than half the thickness of dentin (as assessed radiographically), reversible pulpitis (n = 10), and symptomatic irreversible pulpitis (n = 10) with caries extending more than two thirds of the thickness of dentin. Carious dentin samples were collected from the deepest part of the cavity and stored in RNAlater solution (Ambion Inc, Austin, TX). Eight bacterial taxa were evaluated from the samples: Streptococcus mutans, Lactobacillus fermentum, Veillonella, Actinomyces, Rothia dentocariosa, Olsenella profusa, Prevotella intermedia, and Bifidobacterium dentium. The 16S ribosomal RNA (rRNA) gene and 16S rRNA were quantified by real-time polymerase chain reaction and used to calculate the relative genome abundance and relative ribosomal abundance. The Fisher exact test was used to compare proportions between groups. The mean rank difference between the various groups was assessed using the Kruskal-Wallis test with the Bonferroni-Holm correction.

RESULTS

The reversible pulpitis group had significantly higher 16S rRNA gene and rRNA counts of Actinomyces (P < .001 and P = .002) and B. dentium (P = .005 and P = .007) relative to the NP group. The symptomatic irreversible pulpitis group had significantly higher 16S rRNA gene and rRNA counts of L. fermentum (P < .001 and P < .001), Actinomyces (P < .001 and P < .001), O. profusa (P < .001 and P < .001), P. intermedia (P = .001 and P = .002), and Bifidobacterium (P < .001 and P < .001) relative to the NP group.

CONCLUSIONS

Specific bacterial activity varies in carious dentin of teeth with different pulp conditions.

The Antimicrobial Effect of Pomegranate Peel Extract versus Chlorhexidine in High Caries Risk Individuals Using Quantitative Real-Time Polymerase Chain Reaction: A Randomized Triple-Blind Controlled Clinical Trial

The aim of the present study was to compare the antibacterial effectiveness of chlorhexidine and PPE oral rinse on S. mutans, Lactobacilli, and Veillonella, in clinical salivary samples of patients with advanced stages of dental caries at baseline and two and four weeks with PCR technique. This triple-blind randomized clinical trial involved 60 high caries risk adult patients, 19–59 years of age, randomly allocated into two groups of 30 subjects each. The intervention group received pomegranate peel extract mouthwash, whereas the control group received chlorhexidine mouthwash. Unstimulated pooled saliva was collected from the floor of the mouth before and after the intervention. The quantitative real-time polymerase chain reaction was employed to analyze the bacterial copies of each salivary sample at baseline and two and four weeks. The significance level was fixed at 5% (α = 0.05). Overall comparison of antimicrobial effectiveness across both groups revealed insignificant outcomes. The control group evinced a significant reduction in S. mutans between a specific time, i.e., baseline and 4 weeks (p=0.043). PPE oral rinse as a natural product or ecological alternative was effective in disrupting activity across all microorganisms tested in this triple-blind RCT; however, the nutraceutical, when compared to chlorhexidine, was not as effective against S. mutans.

Evaluation of Periodontal Risk Factors with Quantitative Light-Induced Fluorescence Based Fluorescent Plaque Index, in Comparison to Radiographic and Oral Health Habit Scoring: A Retrospective Case Study

The aim of this study was to evaluate periodontal risk factors with oral health habits and fluorescent plaque index (FPI) using quantitative light-induced fluorescence (QLF) images, and to evaluate their effect on the degree of radiographic bone loss (RBL). Selected were 276 patients over 19 years of age to complete the questionnaire for oral health habit and take QLF images, periapical and panoramic radiographs. Oral health habit score, age, and sex showed a statistically significant correlation with FPI. FPI showed a lower value as the oral health habit score increased and the age decreased. Moreover, females showed lower FPI values than did males. RBL showed a statistically significant positive correlation with age but did not show any correlation with oral health habit scores and sex. There was no correlation between FPI and RBL. The results of this study suggest that the clinical use of QLF allows plaque detection by non-invasive procedures and can aid in a more objective estimation for oral hygiene status.

Healthy Oral Lifestyle Behaviours Are Associated with Favourable Composition and Function of the Oral Microbiota

Modifiable lifestyle interventions may influence dental disease by shifting the composition of the oral microbiota. This study aimed to test whether lifestyle traits are associated with oral microbiota composition and function. Swedish volunteers, aged 16 to 79 years, completed a lifestyle traits questionnaire including lifestyle characteristics and oral health behaviours. Bacterial 16S rDNA amplicons were sequenced and classified into genera and species, using salivary DNA. Microbiota functions were predicted using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States and the KO Database of Molecular Functions by ortholog annotation. Tests for association used partial least squares and linear regression analysis with correction for multiple testing. The main analysis included 401 participants and 229 common bacterial species (found in ≥10% of the participants). The overall microbiota composition was strongly associated with questions "do you think caries is a disease?" and "do you use floss or a toothpick?". Enriched relative abundance of Actinomyces, Campylobacter, Dialister, Fusobacterium, Peptidophaga and Scardovia genera (all p < 0.05 after adjustment for multiple testing), and functional profiles showing enrichment of carbohydrate related functions, were found in participants who answered "no" to these questions. Socio-demographic traits and other oral hygiene behaviours were also associated. Healthier oral microbiota composition and predicted functions are found in those with favourable oral health behaviours. Modifiable risk factors could be prioritized for possible interventions.

Novel lactotransferrin-derived synthetic peptides suppress cariogenic bacteria in vitro and arrest dental caries in vivo: [Novel lactotransferrin-derived anticaries peptides]

Objectives: The aim of the study was to design and synthesise novel lactotransferrin-derived antimicrobial peptides (AMPs) with enhanced antibacterial activity against cariogenic bacteria. Methods: We obtained the LF-1 (WKLLRKAWKLLRKA) and LF-2 (GKLIWKLLRKAWKLLRKA) AMPs, based on the N-terminal functional sequence of lactotransferrin, and characterised their physicochemical properties and secondary structure. Their antibacterial activity against caries-associated bacteria was evaluated using bacterial susceptibility and time-killing assays, as well as transmission electron microscopy (TEM). The antibiofilm activity against Streptococcus mutans biofilms was determined using biofilm susceptibility assays and confocal laser scanning microscopy (CLSM). A rodent model of dental caries was adopted to evaluate their anticaries effectiveness in vivo. Results: Both peptides possessed an α-helical structure with excellent amphipathicity. LF-1 was effective against S. mutans and Actinomyces species, whereas LF-2 showed more potent antibacterial activity than LF-1 against a broader spectrum of tested strains. Both peptides inhibited the formation of S. mutans biofilm starting at 8 μmol/L and exerted effective eradication of S. mutans in preformed biofilms. Both peptides exhibited satisfactory biocompatibility and exerted significant anticaries effects in a rodent model. Conclusion s: Both lactotransferrin-derived peptides displayed strong antimicrobial activity against cariogenic bacteria and S. mutans biofilm in vitro and effectively inhibited dental caries in vivo.

Evaluation of Clinical, Biochemical and Microbiological Markers Related to Dental Caries

Our aim was to evaluate clinical, biochemical and microbiological markers related to dental caries in adults. A sample that consisted of 75 volunteers was utilized. The presence of caries and the presence of plaque and gingival indices were determined. Unstimulated salivary flow, pH, lactate, Streptococcus mutans and Streptococcus dentisani were measured in the participants’ plaque and saliva samples before and after rinsing with a sugar solution. Lactate in plaque was found to be significantly related to age, gender, tooth-brushing frequency, the presence of cavitated caries lesions and plaque and gingival indices (p < 0.05). The levels of S. dentisani in plaque increased significantly with tooth-brushing frequency (p = 0.03). Normalized plaque S. dentisani values and the percentage of S. dentisani were slightly higher in patients with basal lactic acid levels ≤ 50 mg/L. After rinsing with a sugary solution, the percentage of S. mutans levels in plaque were higher in patients with lactic acid levels > 350 mg/L (p = 0.03). Tooth-brushing frequency was the factor which was most associated with oral health. Women reflected better clinical and biochemical parameters than men. Low pH and high lactic acid levels tended to be associated with high caries rates. No association was found between bacteria levels and caries indices.

A three-dimensional-printed SPION/PLGA scaffold for enhanced palate-bone regeneration and concurrent alteration of the oral microbiota in rats

Scaffold implantation for the repair of oral bone defects involves an interplay between the scaffold biomaterial and the microenvironment. However, previous studies on this subject have only considered the effects of the immune system and largely ignored those of the oral microbiota. Accordingly, in the present study, we prepared composite scaffolds comprising a three-dimensional poly(l-lactide-co-glycolide) matrix with a superparamagnetic iron oxide nanoparticle (SPION) coating and used a rat model to evaluate their palate-bone-regenerating effects and their interaction with the oral microbiota. It was found that the SPION coated scaffold induced better bone regeneration than that achieved by the controls. Furthermore, it significantly decreased the operational taxonomic units (OTU) numbers as determined by 16 s rRNA gene sequencing, and also resulted in decreased Chao and ACE alpha diversity indexes compared with those of the controls. However, it had no effect on beta diversity. SPION coated scaffolds caused a shift in oral bacterial composition characterized by a decrease in the Clostridium spp. population, and the dominant flora being Proteobacteria. Furthermore, SPION coated scaffolds upregulated the concentration of serum iron, hepcidin, and P1NP. Thus, SPION coated scaffolds enhanced bone regeneration, and this effect was partly related to alteration of the oral microbiota by the antibacterial effects of SPION. Our findings provide a better understanding of the role of oral microbiota in oral bone regeneration and how SPION coated scaffolds can be used to enhance it.

Antimicrobial photodynamic therapy mediated by methylene blue coupled to β-cyclodextrin reduces early colonizing microorganisms from the oral biofilm

OBJECTIVE

To test the effect of antimicrobial photodynamic therapy (A-PDT) on the oral biofilm formed with early colonizing microorganisms, using the photosensitizer methylene blue coupled with β-cyclodextrin nanoparticles and red light sources laser or LED (λ =660 nm).

METHODS

The groups were divided into (n = 3, in triplicate): C (negative control, 0.9 % NaCl), CX (positive control, 0.2 % chlorhexidine), P (Photosensitizer/Nanoparticle), L (Laser), LED (light-emitting diode), LP (Laser + Photosensitizer/Nanoparticle) and LEDP (LED + Photosensitizer/Nanoparticle). A multispecies biofilm composed ofS. gordonii, S. oralis, S. mitis, and S. sanguinis was grown in microplates containing BHI supplemented with 1% sucrose (w/v) for 24 h. Light irradiations were applied with a laser at 9 J for 90 s (320 J/cm²), or with LED, at 8.1 J for 90 s (8.1 J/cm²). The microbial reduction was assessed by counting viable biofilm microorganisms in selective culture media, before and after the treatments. Data normality was assessed by the Shapiro-Wilk test, and the results were submitted to Kruskal-Wallis analysis, followed by Dunn's test, with a significance level of 5%.

RESULTS

The groups LP and LEDP were able to significantly reduce the biofilm microorganism counts by as much as 4 log₁₀ times compared to the negative control group (p < 0.05) and did not statistically differ from the positive control group (CX) (p > 0.05).

CONCLUSION

The A-PDT mediated by encapsulated β-cyclodextrin methylene blue irradiated by Laser or LED was effective in the microbial reduction of multispecies biofilm composed of early colonizing microorganisms.

Metabolic activity of hydro-carbon-oxo-borate on a multispecies subgingival periodontal biofilm: a short communication

Objective

This study evaluated the metabolic activity of hydro-carbon-oxo-borate complex (HCOBc) on a multispecies subgingival biofilm as well as its effects on cytotoxicity.

Materials and methods

The subgingival biofilm with 32 species related to periodontitis was formed in the Calgary Biofilm Device (CBD) for 7 days. Two different therapeutic schemes were adopted: (1) treatment with HCOBc, 0.12% chlorhexidine (CHX), and negative control group (without treatment) from day 3 until day 6, two times a day for 1 min each time, totaling 8 treatments and (2) a 24-h treatment on a biofilm grown for 6 days. After 7 days of formation, biofilm metabolic activity was determined by colorimetry assay, and bacterial counts and proportions of complexes were determined by DNA-DNA hybridization. Both substances’ cytotoxicity was evaluated by cell viability (XTT assay) and clonogenic survival assay on ovary epithelial CHO-K1 cells and an osteoblast precursor from calvaria MC3T3-E1 cells.

Results

The first treatment scheme resulted in a significant reduction in biofilm’s metabolic activity by means of 77% by HCOBc and CHX treatments versus negative control. The total count of 11 and 25 species were decreased by treatment with hydro-carbon-oxo-borate complex and CHX, respectively, compared with the group without treatment (p < 0.05), highlighting a reduction in the levels of Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, and Fusobacterium periodontium. CHX significantly reduced the count of 10 microorganisms compared to the group treated with HCOBc (p < 0.05). HCOBc and CHX significantly decreased the pathogenic red-complex proportion compared with control-treated biofilm, and HCOBc had even a more significant effect on the red complex than CHX had (p ≤ 0.05). For the second treatment scheme, HCOBc complex and CHX significantly decreased 61 and 72% of control biofilms’ metabolic activity and the counts of 27 and 26 species, respectively. HCOBc complex did not significantly affect the proportions of formed biofilms, while CHX significantly reduced red, orange, and yellow complexes. Both substances exhibited similar cytotoxicity results.

Conclusions

This short communication suggested that the HCOBc complex reduced a smaller number of bacterial species when compared to chlorhexidine during subgingival biofilm formation, but it was better than chlorhexidine in reducing red-complex bacterial proportions. Although HCOBc reduced the mature 6-day-old subgingival multispecies biofilms, it did not modify bacterial complexes’ ratios as chlorhexidine did on the biofilms mentioned above. Future in vivo studies are needed to validate these results.

Clinical relevance

HCOBc complex could be used to reduce red-complex periodontal bacterial proportions.

The association between genetic polymorphisms in matrix metalloproteinases and caries experience

OBJECTIVES

The variation in the caries susceptibility while environmental factors are similar indicates that the effect of individual factors such as genetics on caries process and tooth development should be revealed. The aim of this study was to evaluate the association between genetic polymorphisms in MMP13 (rs2252070) and MMP20 (rs1784418) with caries experience.

MATERIALS AND METHODS

A cross-sectional study was conducted on 200 subjects aged 6 to 14 years. Demographic data, data on oral health habits were obtained through the statements of guardian of the individuals, caries data was collected by clinical examination. Unstimulated whole saliva was collected to extract the genomic DNA. Genotyping of the selected polymorphisms was carried out by real-time PCR. Allele and genotype frequencies were compared between different subgroups considering caries experience. Data were analyzed using SPSS 16.0 by chi-square test and logistic regression analysis.

RESULTS

Allele distribution of MMP13 was different between caries-affected and caries-free subjects. MMP13 A allele increased the caries risk (p=0.005, OR=1.84, 95% CI 1.20-2.82). Allele and genotype distribution of the polymorphism in MMP20 were not associated with caries experience (p>0.05).

CONCLUSIONS

It is concluded that the genetic variation in MMP13 was associated with the caries experience in selected subjects in Turkey.

CLINICAL RELEVANCE

The knowledge regarding association between the MMP genes and caries experience, might benefit the clinical practice, improving caries-preventive and caries-therapeutic approaches.

The oralome and its dysbiosis: New insights into oral microbiome-host interactions

The oralome is the summary of the dynamic interactions orchestrated between the ecological community of oral microorganisms (comprised of up to approximately 1000 species of bacteria, fungi, viruses, archaea and protozoa - the oral microbiome) that live in the oral cavity and the host. These microorganisms form a complex ecosystem that thrive in the dynamic oral environment in a symbiotic relationship with the human host. However, the microbial composition is significantly affected by interspecies and host-microbial interactions, which in turn, can impact the health and disease status of the host. In this review, we discuss the composition of the oralome and inter-species and host-microbial interactions that take place in the oral cavity and examine how these interactions change from healthy (eubiotic) to disease (dysbiotic) states. We further discuss the dysbiotic signatures associated with periodontitis and caries and their sequalae, (e.g., tooth/bone loss and pulpitis), and the systemic diseases associated with these oral diseases, such as infective endocarditis, atherosclerosis, diabetes, Alzheimer's disease and head and neck/oral cancer. We then discuss current computational techniques to assess dysbiotic oral microbiome changes. Lastly, we discuss current and novel techniques for modulation of the dysbiotic oral microbiome that may help in disease prevention and treatment, including standard hygiene methods, prebiotics, probiotics, use of nano-sized drug delivery systems (nano-DDS), extracellular polymeric matrix (EPM) disruption, and host response modulators.

Baicalein Inhibits Streptococcus mutans Biofilms and Dental Caries-Related Virulence Phenotypes

Dental caries, the most common oral disease, is a major public healthcare burden and affects more than three billion people worldwide. The contemporary understanding of the need for a healthy microbiome and the emergence of antimicrobial resistance has resulted in an urgent need to identify compounds that curb the virulence of pathobionts without microbial killing. Through this study, we have demonstrated for the first time that 5,6,7-trihydroxyflavone (Baicalein) significantly downregulates crucial caries-related virulence phenotypes in Streptococcus mutans. Baicalein significantly inhibited biofilm formation by Streptococcus mutans UA159 (MBIC50 = 200 μM), without significant growth inhibition. Notably, these concentrations of baicalein did not affect the commensal S. gordonii. Strikingly, baicalein significantly reduced cell surface hydrophobicity, autoaggregation and acid production by S. mutans. Mechanistic studies (qRT-PCR) showed downregulation of various genes regulating biofilm formation, surface attachment, quorum sensing, acid production and competence. Finally, we demonstrate the potential translational value of baicalein by reporting synergistic interaction with fluoride against S. mutans biofilms.

Relationship between dental and periodontal health status and the salivary microbiome: bacterial diversity, co-occurrence networks and predictive models

The present study used 16S rRNA gene amplicon sequencing to assess the impact on salivary microbiome of different grades of dental and periodontal disease and the combination of both (hereinafter referred to as oral disease), in terms of bacterial diversity, co-occurrence network patterns and predictive models. Our scale of overall oral health was used to produce a convenience sample of 81 patients from 270 who were initially recruited. Saliva samples were collected from each participant. Sequencing was performed in Illumina MiSeq with 2 × 300 bp reads, while the raw reads were processed according to the Mothur pipeline. The statistical analysis of the 16S rDNA sequencing data at the species level was conducted using the phyloseq, DESeq2, Microbiome, SpiecEasi, igraph, MixOmics packages. The simultaneous presence of dental and periodontal pathology has a potentiating effect on the richness and diversity of the salivary microbiota. The structure of the bacterial community in oral health differs from that present in dental, periodontal or oral disease, especially in high grades. Supragingival dental parameters influence the microbiota’s abundance more than subgingival periodontal parameters, with the former making a greater contribution to the impact that oral health has on the salivary microbiome. The possible keystone OTUs are different in the oral health and disease, and even these vary between dental and periodontal disease: half of them belongs to the core microbiome and are independent of the abundance parameters. The salivary microbiome, involving a considerable number of OTUs, shows an excellent discriminatory potential for distinguishing different grades of dental, periodontal or oral disease; considering the number of predictive OTUs, the best model is that which predicts the combined dental and periodontal status.