Isolation and Identification of Potentially Pathogenic Microorganisms Associated with Dental Caries in Human Teeth Biofilms

Oral Hygiene, Dietary Habits, and Saliva Properties in Relation to the Decayed, Missing, and Filled Teeth Index of Dental Students: A Pilot Study

Background and Objectives: Caries development is associated with poor oral hygiene, inadequate dietary habits, quantitative and qualitative food content, and a high level of bacterial plaque. Physical and chemical changes in saliva composition and particularly changes in its buffering capability play a significant role in caries development. This study aimed to determine the predictors of poor oral health among a sample of second-year dental students. Materials and Methods: The oral health of students was estimated with clinical examination and the DMFT index. The interview included questions about demographics status (gender, age), a dietary habits questionnaire, questions about oral hygiene, and a demonstration of tooth brushing technique. Unstimulated saliva samples were collected to measure buffering capacity and pH. Results: Almost half of the students have a low level of caries experience (46.7%), followed by a slightly smaller number having a medium level (41.3%), while one in eight students (12.0%) demonstrates a high level of caries experience. Male students have a statistically higher DMFT index 5.7 ± 1.2 than female participants 4.5 ± 0.5 (p = 0.036). Significant predictors for the DMFT index score in students were milk [β-coefficient = -0.338, p = 0.011] and yoghurt [β-coefficient = 0.284, p = 0.040] consumption. All students brushed their teeth two or more times during the day, usually after waking up before breakfast and before bedtime. Most students (85.3%) apply the proper tooth brushing technique, with female students applying it more frequently (p = 0.038). The mean salivary pH was 6.9, while the mean buffer capacity was 5.8. Female respondents have a statistically lower buffer capacity (5.8 ± 0.5) than male respondents (6.1 ± 0.4) (p = 0.047). Conclusions: Dentistry students are introduced to good oral hygiene habits, especially female students, while dietary habits should be improved. However, one in eight dental students is at high caries risk. By assessing the level of caries experience, targeted strategies can be developed to promote, maintain, and enhance oral health among dental students.

Role of socioeconomic factors and interkingdom crosstalk in the dental plaque microbiome in early childhood caries

Early childhood caries (ECC) is influenced by microbial and host factors, including social, behavioral, and oral health. In this cross-sectional study, we analyze interkingdom dynamics in the dental plaque microbiome and its association with host variables. We use 16S rRNA and ITS1 amplicon sequencing on samples collected from preschool children and analyze questionnaire data to examine the social determinants of oral health. The results indicate a significant enrichment of Streptococcus mutans and Candida dubliniensis in ECC samples, in contrast to Neisseria oralis in caries-free children. Our interkingdom correlation analysis reveals that Candida dubliniensis is strongly correlated with both Neisseria bacilliformis and Prevotella veroralis in ECC. Additionally, ECC shows significant associations with host variables, including oral health status, age, place of residence, and mode of childbirth. This study provides empirical evidence associating the oral microbiome with socioeconomic and behavioral factors in relation to ECC, offering insights for developing targeted prevention strategies.

Synthesis of novel silver-loaded clay AgF@Hec for the prevention of dental cariesin vitro

Dental caries, a chronic infectious disease characterized by tooth mineral loss caused by plaque, is one of the major global public health problems. Silver diamine fluoride (SDF) has been proven to be a highly effective anti-caries drug due to its high bacterial inhibition and remineralization ability. However, the SDF solution is unstable, which immensely limits its clinical application. Therefore, new silver-load clay named AgF@Hec was designed by replacing the NH3with hectorite in this study. Fourier transform infrared spectroscopy and x-ray diffraction spectroscopy were employed to confirm the structure of AgF@Hec. Dynamic light scattering analysis was used to reveal the effect of different hectorite concentrations on the stability of AgF@Hec. Moreover, AgF@Hec exhibits significant remineralization and hardness recovery of the initial carious lesions. Bacteriostatic experiments also proved that it has a significant inhibitory effect onA. Viscosus, S. mutans, S. sanguinis, S. salivarius, Lactobacillus sp.and both gram-positive and gram-negative bacteria. We therefore believed that AgF@Hec should be a promising biomaterial that can be applied in the prevention of dental caries.

The oral microbiome and oral and upper gastrointestinal diseases

Background

Microbiomes are essential components of the human body, and their populations are substantial. Under normal circumstances, microbiomes coexist harmoniously with the human body, but disturbances in this equilibrium can lead to various diseases. The oral microbiome is involved in the occurrence and development of many oral and gastrointestinal diseases. This review focuses on the relationship between oral microbiomes and oral and upper gastrointestinal diseases, and therapeutic strategies aiming to provide valuable insights for clinical prevention and treatment.

Methods

To identify relevant studies, we conducted searches in PubMed, Google Scholar, and Web of Science using keywords such as "oral microbiome," "oral flora, " "gastrointestinal disease, " without any date restrictions. Subsequently, the retrieved publications were subject to a narrative review.

Results

In this review, we found that oral microbiomes are closely related to oral and gastrointestinal diseases such as periodontitis, dental caries, reflux esophagitis, gastritis, and upper gastrointestinal tumors (mainly the malignant ones). Oral samples like saliva and buccal mucosa are not only easy to collect, but also display superior sample stability compared to gastrointestinal tissues. Consequently, analysis of the oral microbiome could potentially serve as an efficient preliminary screening method for high-risk groups before undergoing endoscopic examination. Besides, treatments based on the oral microbiomes could aid early diagnosis and treatment of these diseases.

Conclusions

Oral microbiomes are essential to oral and gastrointestinal diseases. Therapies centered on the oral microbiomes could facilitate the early detection and management of these conditions.

Effectiveness of a novel experimental herbal toothpaste against bacterial consortium associated with dental caries

Background

To evaluate the effectiveness of an experimental toothpaste based on Hypericum laricifolium Juss. essential oil against a bacterial consortium associated with dental caries.

Material and Methods

The antibacterial activity of the essential oil was evaluated by the disk diffusion and microdilution tests against Streptococcus mutans, Streptococcus sanguinis and Streptococcus salivarius. Petri dishes were incubated at 37°C for 24 h. An experimental toothpaste was prepared at a concentration of 201.76 mg/mL. The antibacterial activity of the experimental and six commercial toothpastes were evaluated by agar well-diffusion method. Petri dishes were inoculated with a bacterial consortium prepared with the three strains. 80 mg of the toothpastes were placed in the wells and the Petri dishes were incubated at 37°C for 24 h. The inhibition zones were measured with a digital compass. The differences between the pastas were evaluated with the one-way ANOVA test, with a 5% level of significance.

Results

The essential oil was more effective than 0.12% chlorhexidine in inhibiting the growth of S. mutans (29.02±1.74 mm) and S. sanguinis (21.92±3.43 mm), being more moderate for S. salivarius (17.66±1.11 mm) . In MBC tests, the EO showed complete inhibition of the growth of S. mutans at a concentration of 5% (50.44 mg/mL), 10% (100.88 mg/mL) for S. sanguinis and 2.5% (25.22 mg/mL) for S. salivarius. The experimental toothpaste was effective in inhibiting the growth of the bacterial consortium (31.88±66 mm), having a similar performance to Total Dent, Colgate Total 12, Kolynos® Herbal and Colgate® Herbal (p> 0.05).

Conclusions

The development of an experimental paste based on H. laricifolium Juss. essential oil (0.28% v/v) showed an important antibacterial activity similar to commercial toothpastes against a bacterial consortium of S. mutans, S. sanguinis and S. salivarius. Key words:Antibacterial agents, toothpastes, medicinal plants, Streptococcus mutans, Streptococcus sanguinis, Streptococcus salivarius.

Anticandidal Efficacy of Oral Probiont Limosilactobacillus fermentum Against Dental Caries Pathogens in Children, Tamil Nadu, India

Dental caries remains a prevalent concern among children globally and is associated with Candida sp. Some researchers have suggested probiotic supplements as a possible solution for reducing dental caries. A study conducted in Tamil Nadu focused on collecting 80 dental caries samples from both males and females, obtained from two different locations. The samples underwent processing using the spread plate technique, followed by anticandidal activity assessments. Through ITS sequence analysis, candida strains were identified, including C. albicans (DDGRPO1, DDGRPO2). The study specifically investigated the ability of the probiotic bacterial strain Lb. fermentum cell-free filtrate to inhibit C. albicans. The research revealed that Lb. fermentum probiotics effectively inhibited the growth of C. albicans DDGRP01, displaying strong antifungal activity against Candida sp. (98%). While these results are promising, it is worth mentioning the increasing interest in exploring innovative alternatives to probiotic-based treatments. This avenue of research offers potential for a more comprehensive approach to addressing this issue. Notably, Lb. fermentum, derived from the human oral cavity, emerges as a significant postbiotic candidate for dental prophylaxis, indicating a hopeful direction for future studies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01175-5.

Applications of quaternary ammonium compounds in the prevention and treatment of oral diseases: State-of-the-art and future directions

OBJECTIVES

The aim of this review is to comprehensively summarize the state-of-the-art developments of quaternary ammonium compounds (QACs) in the prevention and treatment of oral diseases. By discussing the structural diversity and the potential killing mechanism, we try to offer some insights for the future research of QACs.

DATA, SOURCES & STUDY SELECTION

A literature search was conducted in electronic databases (Web of Science, PubMed, Medline, and Scopus). Publications that involved the applications of QACs, especially those related to the prevention and treatment of oral diseases, are included.

RESULTS

We have reviewed the relevant research on QACs over the past two decades. The research results indicate that the current applications are mainly focused on dental material modification and direct pharmacological interventions. Concurrently, challenges such as potential risks to normal tissues and impediments in drug resistance and microbial persistence present certain application constraints. The latest studies have encompassed the exploration of smart materials and nanoparticle formulations.

CONCLUSIONS

The killing mechanism may possess a threshold related to charge density. However, the exact process remains enigmatic. The structural diversity and the exploration of intelligent materials and nanoparticle formulations provide directions in development of novel QACs.

CLINICAL SIGNIFICANCE

The intricate oral anatomy, combined with the multifaceted oral microbiome, necessitates specialized materials for the targeted prevention and treatment of oral pathologies. QACs represent a cohort of compounds distinguished by potent anti-infective and anti-tumor attributes. Innovations in intelligent materials and nanoparticle formulations amplify their potential in significantly advancing the prevention and therapeutic interventions for oral diseases.

Microbial Relationship of Carious Deciduous Molars and Adjacent First Permanent Molars

(1) Epidemiological studies have shown that deciduous molar caries are related to and more severe than permanent molar caries. This study aimed to investigate whether caries subtypes in deciduous molars were associated with caries in first permanent molars and to explore taxonomic and functional profiles of the microbiota involved in different subtypes. (2) 42 mixed-dentition children were recruited and were divided into DMC (carious deciduous molars but caries-free first permanent molars; n = 14), C (carious deciduous and first permanent molars; n = 13), and control (n = 15) groups. Metagenomic sequencing was performed for supragingival plaque samples obtained separately from deciduous and first permanent molars. (3) The microbiota of deciduous molars in the DMC and C groups differed not only in species-based beta diversity but also in compositional and functional profiles. In the C group-like subtype, 14 caries-related species and potential pathways were identified that could be responsible for the caries relationship between the deciduous and permanent molars. In the DMC group-like subtype, the overall functional structure, the levels of Leptotrichia wadei, Streptococcus anginosus, and Stomatobaculum longum and KOs in sugar transporters and fermentation, quorum sensing, and TCA cycle in their first permanent molars surprisingly resembled those of the C group rather than the control group. This suggested that these clinically sound first permanent molars were at a greater risk for caries. (4) Classification of deciduous molar caries according to the microbiota could serve as a caries risk predictor for adjacent first permanent molars.

Biofilm modifiers: The disparity in paradigm of oral biofilm ecosystem

A biofilm is a population of sessile microorganisms that has a distinct organized structure and characteristics like channels and projections. Good oral hygiene and reduction in the prevalence of periodontal diseases arise from minimal biofilm accumulation in the mouth, however, studies focusing on modifying the ecology of oral biofilms have not yet been consistently effective. The self-produced matrix of extracellular polymeric substances and greater antibiotic resistance make it difficult to target and eliminate biofilm infections, which lead to serious clinical consequences that are often lethal. Therefore, a better understanding is required to target and modify the ecology of biofilms in order to eradicate the infection, not only in instances of oral disorders but also in terms of nosocomial infections. The review focuses on several biofilm ecology modifiers to prevent biofilm infections, as well as the involvement of biofilm in antibiotic resistance, implants or in-dwelling device contamination, dental caries, and other periodontal disorders. It also discusses recent advances in nanotechnology that may lead to novel strategies for preventing and treating infections caused by biofilms as well as a novel outlook to infection control.

Association of polymicrobial interactions with dental caries development and prevention

Dental caries is a common oral disease. In many cases, disruption of the ecological balance of the oral cavity can result in the occurrence of dental caries. There are many cariogenic microbiota and factors, and their identification allows us to take corresponding prevention and control measures. With the development of microbiology, the caries-causing bacteria have evolved from the traditional single Streptococcus mutans to the discovery of oral symbiotic bacteria. Thus it is necessary to systematically organized the association of polymicrobial interactions with dental caries development. In terms of ecology, caries occurs due to an ecological imbalance of the microbiota, caused by the growth and reproduction of cariogenic microbiota due to external factors or the disruption of homeostasis by one's own factors. To reduce the occurrence of dental caries effectively, and considering the latest scientific viewpoints, caries may be viewed from the perspective of ecology, and preventive measures can be taken; hence, this article systematically summarizes the prevention and treatment of dental caries from the aspects of ecological perspectives, in particular the ecological biofilm formation, bacterial quorum sensing, the main cariogenic microbiota, and preventive measures.

Effects of immunoglobulin Y-loaded amorphous calcium phosphate on dentinal tubules occlusion and antibacterial activity

Aim: This study aimed to evaluate the effects of immunoglobulin Y (IgY)-loaded amorphous calcium phosphate (ACP) (IgY@ACP) on dentinal tubule occlusion and antibacterial activity.

Methodology: IgY@ACP was synthesized based on a biomimetic mineralization strategy. The structure was examined by transmission electron microscopy and Fourier transform infrared spectroscopy. The IgY release property was assessed in vitro. The cell biocompatibility of IgY@ACP was evaluated by CCK-8. The dentin disks were prepared using healthy human molars, and their dentinal tubules were exposed to EDTA. Subsequently, they were randomly selected and treated with or without IgY@ACP for 7 days. The tubule occlusion morphologies and newly formed layers were observed by scanning electron microscopy (SEM) and x-ray diffraction, respectively. To evaluate the acid resistance and abrasion resistance of IgY@ACP, dentin disks that were treated for 1 day were immersed in acid solution or subjected to a toothbrush. The antibacterial effects against Streptococcus mutans (S. mutans) were evaluated by colony-forming unit (CFU) counting, adhesion property assessment, and crystal violet and live/dead bacterial staining. Finally, the occlusion effect was evaluated in rat incisors in vivo. One-way analysis of variance (ANOVA) was performed for statistical analysis. The level of significance was set at 0.05.

Results: IgY@ACP presented an amorphous phase with a nanosize (60–80 nm) and sustained release of protein within 48 h. The CCK-8 results showed that IgY@ACP had good biocompatibility. After treatment with IgY@ACP for 1 day, the majority of dentinal tubules were occluded by a 0.3-μm-thick mineralized layer. Seven days later, all dentinal tubules were occluded by mineralization with a thickness of 1.4 μm and a depth of 16 μm. The newly mineralized layer showed hydroxyapatite-like diffraction peaks. In addition, IgY@ACP had good acid and abrasion resistance. After treatment with IgY@ACP, the CFU counting and adhesion rate of S. mutans were significantly reduced, the crystal violet staining was lighter, and the S. mutans staining revealed more dead cells. Most importantly, IgY@ACP had a certain occluding property in rat incisors in vivo.

Conclusion: IgY@ACP can effectively occlude dentinal tubules with acid-resistant stability and has prominent anti-S. mutans effects, rendering it a potentially suitable desensitization material in the clinic.

[Research Progress in the Relationship Between Lactobacillus and Dental Caries]

Lactobacillus is the first microorganism found to be closely associated with dental caries. It demonstrates acidogenicity, aciduricity, and the ability to bind with collagen and to synthesize extracellular polysaccharides to promote bacterial adhesion. Some lactobacilli inhibit the growth of cariogenic bacteria by producing antibacterial compounds or metabolites, competing with cariogenic bacteria for adhesion sites or co-aggregation, or regulating the expression of genes related to cariogenic virulence. Therefore, researchers have, in recent years, experimented with applying Lactobacillusas probiotics in the prevention and control of caries. However, the cariogenic mechanism of Lactobacillus is still not fully understood, and the potential effects, presumably beneficial, of specific Lactobacillus on oral and intestinal microecology remain unknown. More research needs to be done to combine both the cariogenic and probiotic properties of Lactobacillus, and to comprehensively evaluate the effects of Lactobacillus on oral and systemic health. We, herein, summarized research progress in the cariogenicity and caries prevention effect of Lactobacillus, focusing on a discussion of the role of Lactobacillus in cariogenesis, the development of dental caries, and clinical prevention and control of dental caries, in order to provide new ideas and references for the prevention and control of dental caries.

Oral Microbiota, Its Equilibrium and Implications in the Pathophysiology of Human Diseases: A Systematic Review

Imbalances of the oral microbiota and dysbiosis have traditionally been linked to the occurrence of teeth and oral diseases. However, recent findings indicate that this microbiota exerts relevant influence in systemic health. Dysbiosis of the oral microbiota is implicated in the apparition and progression of cardiovascular, neurodegenerative and other major human diseases. In fact, the oral microbiota are the second most diverse and largely populated microbiota of the human body and its relationships with systemic health, although widely explored, they still lack of proper integration. The purpose of this systematic review is thus to widely examine the implications of oral microbiota in oral, cardiovascular and neurodegenerative diseases to offer integrative and up-to-date interpretations. To achieve that aim, we identified a total of 121 studies curated in PUBMED from the time interval January 2003–April 2022, which after careful screening resulted in 79 studies included. The reviewed scientific literature provides plausible vias of implication of dysbiotic oral microbiota in systemic human diseases, and encourages further research to continue elucidating the highly relevant and still poorly understood implications of this niche microbiota in systemic health. PROSPERO Registration Number: CRD42022299692. This systematic review follows relevant PRISMA guidelines.

Investigation of the Role of Leuconostoc mesenteroides subsp. cremoris in Periodontitis around Abutments of Fixed Prostheses

This study included the role of Leuconostoc mesenteroides subsp. cremoris in oral diseases such as periodontitis. Material and Method. Isolation and identification of Leuconostoc mesenteroides subsp. cremoris from a saliva sample of twenty patients wearing fixed dental prostheses suffering from periodontitis followed by estimating susceptibility generally to the most common antibiotics and specifically to chlorhexidine (CHX) to determine the MIC of CHX and also screening of the strength of biofilm production under aerobic and anaerobic conditions; here, the study included six groups: Group I: screening of biofilm formation under aerobic condition, Group II: screening the MIC of CHX effect on biofilm formation under aerobic condition, Group III: screening of the MIC of CHX effect on preformed biofilm under aerobic condition, Group IV: screening of biofilm formation under anaerobic condition, Group V: screening of MIC of CHX effect on biofilm formation under anaerobic condition, and Group VI: screening of MIC of CHX effect on preformed biofilm under anaerobic condition. Results. The results showed that about 5 (25%) isolates were identified as L. mesenteroides subsp. cremoris, while 75% are other isolates. Furthermore, susceptibility results to antibiotic showed the sensitivity to penicillin (100%), azithromycin (100%), ciprofloxacin (100%), tetracycline (100%), gentamicin (100%), doxycycline (100%), vancomycin (100%), ofloxacin (60%), chloramphenicol (80%), ampicillin (80%), and cefoxitin (60%). On the other side, the biofilm production assays revealed that all isolates were moderate biofilm former under the aerobic and anaerobic conditions but for the biofilm treated with MIC of CHX, the current study noticed that the strength of the biofilm became weaker in aerobic and anaerobic conditions; regardless, the strength of the biofilm under anaerobic conditions was higher than in that under aerobic conditions, with no significant differences at p ≤ 0.05 depending on the statistical analysis (T-test) before and after the treatment with MIC of CHX in aerobic and anaerobic conditions. Conclusions. The presence of mesenteroides subsp. cremoris in the oral cavity is due to eating foods and vegetables; based on the strength of the biofilm and sensitivity tests, the isolates have less pathogenicity in the oral cavity due to the weakness of the biofilm production and the lack of resistance to antibiotics.

Acidogenic and aciduric properties of Streptococcus mutans serotype c according to its genomic variability

Streptococcus mutans (S. mutans) has a wide genetic diversity that contributes to its phenotypic heterogeneity, and may be related to attributes associated with acidogenicity and aciduricity. The aim of this study was to evaluate the acidogenic and aciduric properties of S. mutans serotype c isolates from saliva of schoolchildren according to the genomic variability. S. mutans isolates were identified by polymerase chain reaction. Fifty S. mutans serotype c isolates were genotyped by pulsed field gel electrophoresis and tested for their ability to produce and resist acid. Three specific genotypes were identified in the caries-active group and only one in the caries-free group. Although isolates were similarly acidogenic, an exclusive caries-active genotype had the greatest glycolytic activity. In contrast, isolates exhibited variable aciduricity, and three caries-active genotypes were the least aciduric. We concluded that there is genetic variability within serotype c. Acid production was similar regardless of the caries status but correlated with the number of genotypes. In addition, resistance to acid could be an important characteristic for the establishment and colonisation of specific genotypes in children with caries. However, it is important to evaluate children's intrinsic characteristics and other phenotypic properties to explain the physiopathological behaviour of the different genotypes.

Pu'er tea rich in strictinin and catechins prevents biofilm formation of two cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus

Cariogenic bacteria, such as Streptococcus mutans and Streptococcus sobrinus, are main pathogens responsible for human dental caries. Pu'er tea is empirically observed to prevent tooth decay. Besides caffeine and catechins commonly found in oolong tea, strictinin is also found as an abundant phenolic compound in Pu'er tea. Infusion of Pu'er tea as well as single compound, strictinin, caffeine or (−)-epigallocatechin gallate (EGCG) was examined for its inhibitory effects on S. mutans and S. sobrinus. Relatively weak inhibition of bacterial growth was observed for these Pu'er tea constituents. However, biofilm formation of S. mutans or S. sobrinus was strongly prevented by the infusion of Pu'er tea as well as by strictinin or EGCG, but not caffeine. Relatively, strictinin showed a higher potency than EGCG to prevent biofilm formation. Anti-caries effect of Pu'er tea seems to be resulted from the prevention of biofilm formation of cariogenic bacteria mainly by strictinin and catechins.