The Oral Microbiota

The prevalence of oral mucositis after radiotherapy in patients with Head and Neck Cancer and its associated factors: a meta-analysis

OBJECTIVES

Although the discussion about oral mucositis in Head and Neck Cancer (HNC) patients has become a prominent issue, its incidence and influencing factors have not been thoroughly synthesized. This meta-analysis aims to integrate the prevalence and associated factors of radiation-induced oral mucositis among HNC patients.

METHODS

This study searched the following electronic databases: PubMed, the Cochrane Database, the Web of Science, EMBASE, CNKI, the Wanfang Database, and the VIP Database. The publication timeframe for the included studies ranged from January 2005 until January 2024. Two investigators used the NOS scale and AHRQ evaluation criteria for quality evaluation. All qualified studies and statistical analyses were conducted using RevMan 5.2 and Stata 17.0.

RESULTS

Thirty eligible studies were included in the analysis. The results show that the prevalence of radiation-induced oral mucositis in HNC patients was 94% [95% CI (89%, 98%)]. Furthermore, the prevalence of severe radiation-induced oral mucositis in HNC patients is 37% [95%CI (29%, 45%)]. Chemotherapy, smoking history, diabetes, oral PH ≤ 7.0, and alcohol consumption are the main risk factors for radioactive oral mucositis. In addition, BMI > 24.0 kg/m2, no use of antibiotics, and no use of oral mucosal protective agents are associated with radioactive oral mucositis.

CONCLUSIONS

This meta-analysis underscores a significantly high prevalence of radiation-induced oral mucositis in HNC patients. Establishing healthy lifestyle habits and maintaining a healthy oral environment are pivotal in preventing radiation-induced oral mucositis.

Dydrogesterone alleviates periodontitis in perimenopausal women undergoing periodontal therapy by decreasing inflammation and mediating oral microbiota

OBJECTIVE

Dydrogesterone (DG), a synthetic isomer of progesterone, plays a potential regulatory role in the periodontal environment. The aim of this study was to investigate the potential effects of DG on periodontitis under periodontal therapy (PT) and the underlying mechanisms related to oral microbiota.

METHODS

As a cohort study, perimenopausal women with periodontitis and abnormal uterine bleeding associated with ovulatory dysfunction were screened. A total of 30 women received PT (PT group) and 30 women received PT and oral DG 10 mg twice/day for 10 days/month (PT + DG group). At baseline and 3 months after treatment, pocket probing depth (PPD), bleeding index (BI), bleeding on probing (BOP), plaque index, CRP, IL-6, and TNF-α were measured. Additionally, 16S rDNA sequencing was performed to determine the characteristics of oral microbiota, mainly in terms of abundance, diversity, composition, and community structure.

RESULTS

Three months after treatment, the levels of PPD, BI, and BOP, as well as the levels of CRP, IL-6, and TNF-α in gingival crevicular fluid were significantly lower in the PT + DG group than those in the PT group. After treatment, a relatively lower microbial abundance, and some differences in microbial composition were revealed between the PT and PT + DG groups. At the genus level, significantly fewer Escherichia-Shigella, Porphyromonas, and Absconditabacteriales (SR1), and more Lactobacillus, Gordonia, Bifidobacterium, and Oribacterium were found in the PT group than in the PT + DG group.

CONCLUSIONS

DG enhances the effect of PT on inhibiting inflammatory response in women with periodontitis by mediating oral microbiota.

Effects of 3'-sialyllactose, saliva, and colostrum on Candida albicans biofilms

BACKGROUND

Faria et al. evaluated the initial adhesion and biofilm formation of Candida albicans in vitro in the presence of saliva, human colostrum, and 3'-sialyllactose. Colostrum applied either before or after inoculation with saliva did not differ from that of the control biofilms (p<0.05). In contrast, colostrum applied during C. albicans inoculation resulted in a higher biomass than the control (p<0.05). Saliva without colostrum decreased the biofilm biomass (p<0.05), and the application of 3'- sialyllactose reduced biofilm formation regardless of the timing of application (p<0.05). Candidiasis can present as localized or systemic infections. Disseminated infections in newborns and adults can be life-threatening, with high mortality and morbidity rates (40-60%), and rank as the fourth most common type of nosocomial infection. Oral candidiasis is a local condition affecting 10-15% of children in their first months of life. Saliva and 3'-sialyllactose can disrupt the initial development of Candida albicans biofilm. The effect of colostrum needs to be elucidated because it may hinder initial adhesion but promote fungal proliferation after application.

OBJECTIVE

The aim of this study was to investigate the effects of saliva, human colostrum, and 3'-sialyllactose on the initial adhesion and biofilm formation of Candida albicans in vitro.

METHODS

Colostrum and saliva samples were collected from 30 postpartum mothers and newborns, respectively. An 18h culture of C. albicans was treated with colostrum, 3'-sialyllactose, saliva, or a combination of colostrum and saliva at three different time points: before, during, and 24h after C. albicans inoculation. Biofilm assays were conducted in sterile 96-well flat-bottom microtiter plates for 24h. Biofilms were fixed, washed, stained with crystal violet, and extracted. Absorbance was measured to evaluate biofilm biomass.

RESULTS

The combined application of colostrum and saliva before and after microbial inoculation did not differ from the control biofilms (p<0.05). In contrast, the combined application of colostrum and saliva during C. albicans application resulted in a higher biomass than the control (p<0.05). Saliva alone decreased the biofilm biomass (p<0.05), and the application of 3'-sialyllactose reduced biofilm formation regardless of the timing of application (p<0.05).

CONCLUSION

Saliva contributed to the proliferation of biofilms, while colostrum did not prevent initial adhesion but influenced biofilm accumulation and development. In contrast, 3'-sialyllactose significantly decreased biofilm formation at all application times. These findings underscore the importance of colostrum as a potent oral antimicrobial biofluid.

Barriers and Facilitators Concerning Involuntary Oral Care for Individuals with Dementia: A Qualitative Study

Many individuals with dementia show care-resistant behavior toward oral care, while care providers are often reluctant to provide it involuntarily, risking negative health outcomes. This study aims to identify the barriers and facilitators of providing involuntary oral care for individuals with dementia who show care-resistant behavior. In total, 32 semi-structured one-on-one interviews with healthcare providers were conducted. Through the interviews, multiple barriers and facilitators were identified and divided into four main themes, each containing multiple sub-themes: (1) communication (between dental and non-dental care providers, and amongst non-dental care providers themselves), (2) logistics (materials, transportation, and staff and time), (3) knowledge (training, awareness of oral health problems, and assessment of severity of oral health problems), and (4) oral care provision (psychology care providers, attitude concerning involuntary oral care, ethical and legal considerations, and sedation). Our study shed more light on the barriers and facilitators regarding involuntary oral care provision to older individuals with dementia. Multiple recommendations were provided, including designating nurses to help monitor oral health, involving dental professionals in multidisciplinary team meetings, discussing a shift in attitude concerning oral care, providing clear guidelines and protocols for sedation and daily oral care provision, and performing more research into involuntary oral care.

Variations in salivary microbiome and metabolites are associated with immunotherapy efficacy in patients with advanced NSCLC

Lung cancer is a leading cause of cancer mortality, with non-small cell lung cancer (NSCLC) comprising the majority of cases. Despite the advent of immune checkpoint inhibitors (ICIs), a significant number of patients fail to achieve a durable response, highlighting the need to understand the factors influencing treatment efficacy. Saliva samples and tumor samples were collected from 20 NSCLC patients. The salivary microbiota was profiled using metagenomic next-generation sequencing, and metabolites were analyzed via liquid chromatography-mass spectrometry to identify correlations among bacteria, metabolites, and immunotherapy responses. Immunohistochemistry (IHC) analysis of tissue samples verified the result. Besides, in vitro experiments and tumor tissue microarray, including 70 NSCLC patients, were utilized to further explore the potential mechanism linking the oral microbiome and immunotherapy efficacy. The study revealed several differential species and distinct metabolite compositions between responders and non-responders to ICI therapy in NSCLC and explored correlations and mechanisms between microbiota metabolites and immunotherapy resistance. Notably, it was found that several Neisseria and Actinomyces species were significantly enriched in responders and identified lipids and lipid-like molecules associated with PD-L1 expression levels and treatment outcomes. Importantly, several differential lipid molecules were associated with differential species. Further, in vitro experiments and IHC experiments indicated that abnormal fat metabolism linked to dysbiosis is correlated with immunotherapy resistance through regulation of CD8+ T cell activity/infiltration and PD-L1 expression. Specific saliva microbiome and its associated lipids metabolites are significantly associated with the efficacy of ICI-based therapy in lung cancer. Our findings suggest that oral microbiome modulation and targeting lipid metabolism could improve immunotherapy responses, offering new avenues for personalized treatment strategies.IMPORTANCEIn non-small cell lung cancer, our study links specific salivary microbiome profiles and related lipid metabolites to the efficacy of immune checkpoint inhibitor (ICI) therapies. Responders showed enrichment of certain Neisseria and Actinomyces species and distinct lipid compositions. These lipids correlate with PD-L1 expression and CD8+ T cell activity, affecting treatment outcomes. Our results imply that modulating the oral microbiome and targeting lipid metabolism may enhance ICI effectiveness, suggesting novel personalized therapeutic approaches.

Microbial dysbiosis in periodontitis and peri-implantitis: pathogenesis, immune responses, and therapeutic

The oral microbiome comprises over 700 distinct species, forming complex biofilms essential for maintaining oral and systemic health. When the microbial homeostasis in the periodontium is disrupted, pathogens within the biofilm can cause periodontitis and peri-implantitis, inducing host immune responses. Understanding the role of microbial communities and the immune mechanisms in oral health and disease is crucial for developing improved preventive, diagnostic and therapeutic strategies. However, many questions remain about how changes in bacterial populations contribute to the development and progression of these conditions. An electronic and manual literature search was conducted using PubMed, Excerpta Medica, Frontiers Reports and the Wiley Online Library databases for relevant articles. Data from these publications were extracted and the overall findings were summarized in a narrative manner. The variations in microbial communities and immune responses of periodontitis and peri-implantitis are explored. Dysbiosis of the subgingival microbiome-characterized by an increase in pathogenic bacteria such as Porphyromonas gingivalis, Tannerella forsythia, and Aggregatibacter actinomycetemcomitans-plays a pivotal role in the initiation and progression of periodontitis. As for peri-implantitis, alterations include a higher abundance of opportunistic pathogens and reduced microbial diversity around implants. Moreover, oral dysbiosis potentially influencing systemic health through immune-mediated pathways. Regional immunity of periodontium involving neutrophils, T helper cells-17, and immune-related cytokines is crucial for maintaining periodontal homeostasis and responding to microbial imbalances. Additionally, the impact of non-mechanical treatments-such as probiotics and laser therapy-on the oral microbiome is discussed, demonstrating their potential in managing microbial dysbiosis. These findings underscore that bacterial dysbiosis is a central factor in the development of periodontitis and peri-implantitis. Maintaining microbial balance is essential for preventing these diseases, and interventions targeting the microbiome could enhance treatment outcomes. Strategies focusing on controlling pathogenic bacteria, modulating immune responses, and promoting tissue regeneration are key to restoring periodontal stability. Further research is needed to clarify the mechanisms underlying the transition from peri-implant mucositis to peri-implantitis and to optimize prevention and treatment approaches, considering the complex interactions between the microbiome and host immunity.

Advancing dental biofilm models: the integral role of pH in predicting S. mutans colonization

Mathematical models can provide insights into complex interactions and dynamics within microbial communities to complement and extend experimental laboratory approaches. For dental biofilms, they can give a basis for evaluating biofilm growth or the transition from health to disease. We have developed mathematical models to simulate the transition toward a cariogenic microbial biofilm, modeled as the overgrowth of Streptococcus mutans within a five-species dental community. This work builds on experimental data from a continuous flow reactor with hydroxyapatite coupons for biofilm growth, in a chemically defined medium with varying concentrations of glucose and lactic acid. The biofilms formed on the coupons were simulated using individual-based models (IbMs), with bacterial growth modeled using experimentally measured kinetic parameters. The IbM assumes that the maximum theoretical growth yield for biomass is dependent on the local concentration of reactants and products, while the growth rates were described using traditional Monod equations. We have simulated all the conditions studied experimentally, considering different initial relative abundance of the five species, and also different initial clustering in the biofilm. The simulation results only reproduced the experimental dominance of S. mutans at high glucose concentration after we considered the species-specific effect of pH on growth rates. This highlights the significance of the aciduric property of S. mutans in the development of caries. Our study demonstrates the potential of combining in vitro and in silico studies to gain a new understanding of the factors that influence dental biofilm dynamics.IMPORTANCEWe have developed in silico models able to reproduce the relative abundance measured in vitro in the synthetic dental biofilm communities growing in a chemically defined medium. The advantage of this combination of in vitro and in silico models is that we can study the influence of one parameter at a time and aim for direct validation. Our work demonstrates the utility of individual-based models for simulating diverse conditions affecting dental biofilm scenarios, such as the frequency of glucose intake, sucrose pulsing, or integration of pathogenic or probiotic species. Although in silico models are reductionist approaches, they have the advantage of not being limited in the scenarios they can test by the ethical consideration of an in vivo system, thus significantly contributing to dental biofilm research.

Symbiosis Between the Oral Microbiome and the Human Host: Microbial Homeostasis and Stability of the Host

The oral cavity presents a highly diverse microbial composition. All the three domains of life, Bacteria, Eukarya, and Archaea, as well as viruses constitute the oral microbiome. Bacteria are among the most abundant microorganisms in the oral cavity, followed by viruses, fungi, and Archaea. These microorganisms tend to live in harmony with each other and with the host by preventing the colonization of oral sites by exogenous microorganisms. Interactions between the host and its microbiota are crucial for keeping ecological stability in the oral cavity and a condition compatible with oral health. This chapter focuses on describing the oral microbiota in healthy individuals based on both targeted and nontargeted genome sequencing methods and the functional activity played by those microorganisms based on metagenomic, metatranscriptomic, metaproteomic, and metabolomic analyses. Additionally, this chapter explores mutualistic and antagonistic microbe-microbe relationships. These interactions are mediated by complex mechanisms like cross-feeding networks, production of bacteriocins and secondary metabolites, synthesis of pH-buffering compounds, and the use of universal signaling molecules. At last, the role played by host-microbe interactions on colonization resistance and immune tolerance will help provide a better understanding about the harmonious and peaceful coexistence among host and microbial cells under oral health-related conditions.

Microbial community composition in subgingival plaques and heterogeneity of tumor tissue TCRβ CDR3 repertoire in patients with moderate-to-severe periodontitis and oral squamous cell carcinoma

BACKGROUND

The human oral cavity contains over 700 types of bacteria that may protect the body against colonization by exogenous pathogens and maintain relative homeostasis. However, alterations in the immune status can disrupt the balance between microorganisms and the host, inducing various diseases such as oral cancer and diabetes mellitus. The mechanism underlying this process is not clearly understood.

OBJECTIVE

The purpose of this study was to investigate the relationships between subgingival bacteria, T-cell receptor β-chain complementarity-determining region 3 (TCRβ CDR3), and the development oforal squamous cell carcinoma (OSCC).

METHODS

We grouped patients as "healthy periodontal" (H), "moderate-to-severe chronic periodontitis" (C), and "moderate-to-severe chronic periodontitis with OSCC" (T). Bacterial groups were "subgingival plaque" (bp) and "gingival/tumor tissue" (g). We also recorded patients' age, gender, attachment level (AL), bleeding on probing (BOP), and probing depth (PD). We extracted and sequenced RNA from plaques, gingival tissues, tumors, and teeth. We performed high-throughput sequencing on TCRβ CDR3 and plaque bacteria.

RESULTS

Synergistetes and Veillonella parvula were more abundant in the H group than in the T group. Granulicatella, Peptostreptococcus, and Streptococcus infantis were enriched in the T-bp group. AL, BOP, and PD were positively correlated with Granulicatella, Peptostreptococcus, and Pseudomonas but negatively correlated with Prevotella nigrescens and V. parvula. TCRβ CDR3 diversity was C > H > T. TCR β-chain Variable gene (TRBV)20-1 usage varied among the H, C, and T groups. TRBV2 and TRBV5-1 usage was greater in the T group than in the C group. TRBJ1-1, TRBJ1-2, TRBJ2-2, TRBJ2-7, and TRBJ2-5 were most frequently used.

CONCLUSIONS

These trends and the reduction of gingival Synergistetes were correlated with OSCC. TCRβ CDR3 diversity was the lowest in patients in the T group, and there were considerable changes in the expression of TRBV2 and TRBJ. Therefore, plaque bacterial composition can influence TCRβ CDR3.

Gallium-doped zirconia coatings modulate microbiological outcomes in dental implant surfaces

Despite the significant recent advances in manufacturing materials supporting advanced dental therapies, peri-implantitis still represents a severe complication in dental implantology. Herein, a sol-gel process is proposed to easily deposit antibacterial zirconia coatings onto bulk zirconia, material, which is becoming very popular for the manufacturing of abutments. The coatings' physicochemical properties were analyzed through x-ray diffraction and scanning electron microscopy-energy-dispersive x-ray spectroscopy investigations, while their stability and wettability were assessed by microscratch testing and static contact angle measurements. Uniform gallium-doped tetragonal zirconia coatings were obtained, featuring optimal mechanical stability and a hydrophilic behavior. The biological investigations pointed out that gallium-doped zirconia coatings: (i) displayed full cytocompatibility toward human gingival fibroblasts; (ii) exhibited significant antimicrobial activity against the Aggregatibacter actinomycetemcomitans pathogen; (iii) were able to preserve the commensal Streptococcus salivarius. Furthermore, the proteomic analyses revealed that the presence of Ga did not impair the normal oral microbiota. Still, interestingly, it decreased by 17% the presence of Fusobacterium nucleatum, a gram-negative, strictly anaerobic bacteria that is naturally present in the gastrointestinal tract. Therefore, this work can provide a valuable starting point for the development of coatings aimed at easily improving zirconia dental implants' performance.

Revisiting the Concepts of Prebiotic and Prebiotic Effect in Light of Scientific and Regulatory Progress-A Consensus Paper From the Global Prebiotic Association

The term prebiotic has been used for almost 3 decades and has undergone numerous updates over the years. The scientific literature reveals that despite continuous efforts to establish a globally unified definition to guide jurisdictional regulations and product innovations, ambiguity continues to surround the terms prebiotic and prebiotic effect, leading to products that lack in full regulatory adherence being marketed worldwide. Thus, to reflect the current state of scientific research and knowledge and for the continuous advancement of the category, an update to the current prebiotic definition is warranted. This update includes removing the term selectivity, considering additional locations of action besides the gut, highlighting prebiotic performance benefits such as cognitive and athletic, and providing a clear standalone definition for prebiotic effect. The Global Prebiotic Association (GPA) is a leading information and industry hub committed to raising awareness about prebiotics, their emerging and well-established health benefits, and prebiotic product integrity and efficacy. In this position paper, GPA builds on previous prebiotic definitions to propose the following expanded definition for prebiotic: "a compound or ingredient that is utilized by the microbiota producing a health or performance benefit." In addition to prebiotic, GPA also defines prebiotic effect as "a health or performance benefit that arises from alteration of the composition and/or activity of the microbiota, as a direct or indirect result of the utilization of a specific and well-defined compound or ingredient by microorganisms." With these 2 definitions, GPA aims to paint a clearer picture for the term prebiotic, and by incorporating an industry point of view, these updated definitions may be used alongside current scientific and regulatory perspectives to move the category forward.

Oral inoculation of Fusobacterium nucleatum exacerbates ulcerative colitis via the secretion of virulence adhesin FadA

Fusobacterium nucleatum (F. nucleatum), an anaerobic resident of the oral cavity, is increasingly recognized as a contributing factor to ulcerative colitis (UC). The adhesive properties of F. nucleatum are mediated by its key virulence protein, FadA adhesin. However, further investigations are needed to understand the pathogenic mechanisms of this oral pathogen in UC. The present study aimed to explore the role of the FadA adhesin in the colonization and invasion of oral F. nucleatum in dextran sulphate sodium (DSS)-induced colitis mice via molecular techniques. In this study, we found that oral inoculation of F. nucleatum strain carrying the FadA adhesin further exacerbated DSS-induced colitis, leading to elevated alveolar bone loss, disease severity, and mortality. Additionally, CDH1 gene knockout mice treated with DSS presented increases in body weight and alveolar bone density, as well as a reduction in disease severity. Furthermore, FadA adhesin adhered to its mucosal receptor E-cadherin, leading to the phosphorylation of β-catenin and the degradation of IκBα, the activation of the NF-κB signalling pathway and the upregulation of downstream cytokines. In conclusion, this research revealed that oral inoculation with F. nucleatum facilitates experimental colitis via the secretion of the virulence adhesin FadA. Targeting the oral pathogen F. nucleatum and its virulence factor FadA may represent a promising therapeutic approach for a portion of UC patients.

Effect of Nd:YAG Laser Irradiation on the Growth of Oral Biofilm

BACKGROUND

Oral microbiota comprises a wide variety of microorganisms. The purpose of this study was to evaluate the effects of Nd:YAG laser with a 1064 nm wavelength on the in vitro growth of Candida albicans, Candida glabrata, and Streptococcus mutans clinical strains, as well as their biofilm. The study also aimed to determine whether the parameters recommended for photobiomodulation (PBM) therapy, typically used for tissue wound healing, have any additional antibacterial or antifungal effects.

MATERIAL AND METHODS

Single- and dual-species planktonic cell solution and biofilm cultures of Streptococcus mutans, Candida albicans, and Candida glabrata were irradiated using an Nd:YAG laser (LightWalker; Fotona; Slovenia) with a flat-top Genova handpiece. Two test groups were evaluated: Group 1 (G-T1) exposed to low power associated parameters (irradiance 0.5 W/cm2) and Group 2 (G-T2) with higher laser parameters (irradiance 1.75 W/cm2). Group 3 (control) was not exposed to any irradiation. The lasers' effect was assessed both immediately after irradiation (DLI; Direct Laser Irradiation) and 24 h post-irradiation (24hLI) of the planktonic suspension using a quantitative method (colony-forming units per 1 mL of suspension; CFU/mL), and the results were compared with the control group, in which no laser was applied. The impact of laser irradiation on biofilm biomass was assessed immediately after laser irradiation using the crystal violet method.

RESULTS

Nd:YAG laser irradiation with photobiomodulation setting demonstrated an antimicrobial effect with the greatest immediate reduction observed in S. mutans, achieving up to 85.4% reduction at the T2 settings. However, the laser's effectiveness diminished after 24 h. In single biofilm cultures, the highest reductions were noted for C. albicans and S. mutans at the T2 settings, with C. albicans achieving a 92.6 ± 3.3% reduction and S. mutans reaching a 94.3 ± 5.0% reduction. Overall, the T2 settings resulted in greater microbial reductions compared to T1, particularly in biofilm cultures, although the effectiveness varied depending on the microorganism and culture type. Laser irradiation, assessed immediately after using the crystal violet method, showed the strongest biofilm reduction for Streptococcus mutans in the T2 settings for both single-species and dual-species biofilms, with higher reductions observed in all the microbial samples at the T2 laser parameters (p < 0.05) Conclusion: The Nd:YAG laser using standard parameters typically applied for wound healing and analgesic effects significantly reduced the number of Candida albicans; Candida glabrata; and Streptococcus mutans strains.

Towards Wiser Prescribing of Antibiotics in Dental Practice: What Pharmacists Want Dentists to Know

Antibiotics have various indications for treatment and prophylaxis in dental practice. While only a handful of antibiotics are typically prescribed in dentistry, unlike in medicine, clear indications and appropriate dosing and duration remain controversial among antibiotic-prescribing dentists, which may result in inappropriate or excessive antibiotic prescriptions. This practice can increase the risk of antibiotic resistance and expose patients to unnecessary side effects. Moreover, the concept of antibiotic stewardship in dental practice remains in its early stages. This review was developed by pharmacists (general and infectious disease pharmacists) in collaboration with a periodontist and a maxillofacial surgeon to provide an antibiotic prescription guide for dentists who frequently prescribe antibiotics. It also sheds light on antibiotic stewardship. The review discusses in detail antibiotic indications for treatment and prophylaxis in dental practice and provides tables that can be used by dentists in their everyday practice. It also discusses the concept of antibiotic stewardship and provides recommendations that can be applied to the practice of antibiotic prescribing in dentistry. Antibiotic prescribing in dental practice should be limited to cases with documented infections or when indicated for prophylaxis. Every dentist can act as an antibiotic steward by prescribing antibiotics wisely and only when necessary, using their discernment to identify appropriate cases and exclude those that do not meet infection criteria. Collaboration with pharmacists is encouraged to provide such recommendations and implement antibiotic stewardship interventions, such as developing antibiotic prescription protocols.

Periodontal pathogens and cancer development

Increasing evidence suggests a significant association between periodontal disease and the occurrence of various cancers. The carcinogenic potential of several periodontal pathogens has been substantiated in vitro and in vivo. This review provides a comprehensive overview of the diverse mechanisms employed by different periodontal pathogens in the development of cancer. These mechanisms induce chronic inflammation, inhibit the host's immune system, activate cell invasion and proliferation, possess anti-apoptotic activity, and produce carcinogenic substances. Elucidating these mechanisms might provide new insights for developing novel approaches for tumor prevention, therapeutic purposes, and survival improvement.

The Effect of Dietary Types on Gut Microbiota Composition and Development of Non-Communicable Diseases: A Narrative Review

INTRODUCTION

The importance of diet in shaping the gut microbiota is well established and may help improve an individual's overall health. Many other factors, such as genetics, age, exercise, antibiotic therapy, or tobacco use, also play a role in influencing gut microbiota.

AIM

This narrative review summarizes how three distinct dietary types (plant-based, Mediterranean, and Western) affect the composition of gut microbiota and the development of non-communicable diseases (NCDs).

METHODS

A comprehensive literature search was conducted using the PubMed, Web of Science, and Scopus databases, focusing on the keywords "dietary pattern", "gut microbiota" and "dysbiosis".

RESULTS

Both plant-based and Mediterranean diets have been shown to promote the production of beneficial bacterial metabolites, such as short-chain fatty acids (SCFAs), while simultaneously lowering concentrations of trimethylamine-N-oxide (TMAO), a molecule associated with negative health outcomes. Additionally, they have a positive impact on microbial diversity and therefore are generally considered healthy dietary types. On the other hand, the Western diet is a typical example of an unhealthy nutritional approach leading to an overgrowth of pathogenic bacteria, where TMAO levels rise and SCFA production drops due to gut dysbiosis.

CONCLUSION

The current scientific literature consistently highlights the superiority of plant-based and Mediterranean dietary types over the Western diet in promoting gut health and preventing NCDs. Understanding the influence of diet on gut microbiota modulation may pave the way for novel therapeutic strategies.

Frequent toothbrushing boosts resilience among children in poverty: results from a population-based longitudinal study

BACKGROUND

Poverty negatively impacts beneficial aspects of mental development, such as resilience. Toothbrushing, an oral health behavior, has the potential to protect children's resilience through its anti-inflammatory and self-management effects and may be more effective for children, especially children in poverty. This study investigated whether toothbrushing boosts resilience among children, especially children under poverty, and modifies the association between poverty and resilience using a longitudinal population sample of school children.

METHODS

Data from the Adachi Child Health Impact of Living Difficulty (A-CHILD Study) were analyzed. A baseline study was conducted in 2015 in which the children were in first grade and followed through fourth grade (N = 3459, response rate: 80%, follow-up rate: 82%). Poverty was assessed by material deprivation (life-related deprivation and child-related deprivation) and annual household income at baseline. Children's toothbrushing frequency was assessed at baseline and classified into less than twice a day or twice or more a day. Children's resilience was assessed at baseline and follow-up using the Children's Resilient Coping Scale (range 0-100).

RESULTS

Children who brushed their teeth twice or more a day in first grade had 3.50 points greater resilience scores in fourth grade than those who brushed their teeth less than twice a day in first grade. After adjusting for confounders, including resilience in first grade, among underpoverty children, those who brushed their teeth twice or more a day in first grade had higher resilience scores [2.66 (95% CI = 0.53, 4.79)] than those who brushed their teeth less than twice a day. Among nonpoverished children, toothbrushing frequency in first grade did not significantly correlate with resilience in fourth grade.

CONCLUSIONS

The beneficial effect of toothbrushing twice or more a day on resilience was more significant among children in poverty than among those without poverty in elementary school in Japan. Health policy focused on frequent toothbrushing may contribute to boosting resilience among children living in poverty.

Production and characterization of the lipopeptide with anti-adhesion for oral biofilm on the surface of titanium for dental implants

Titanium implants are subject to bacterial adhesion and peri-implantitis induction, and biosurfactants bring a new alternative to the fight against infections. This work aimed to produce and characterize the biosurfactant from Bacillus subtilis ATCC 19,659, its anti-adhesion and antimicrobial activity, and cell viability. Anti-adhesion studies were carried out against Streptococcus sanguinis, Staphylococcus aureus, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Proteus mirabilis as the minimum inhibitory concentration and the minimum bactericidal concentration. Cell viability was measured against osteoblast and fibroblast cells. The biosurfactant was classified as lipopeptide, with critical micelle concentration at 40 µg mL- 1, and made the titanium surface less hydrophobic. The anti-adhesion effect was observed for Staphylococcus aureus and Streptococcus sanguinis with 54% growth inhibition and presented a minimum inhibitory concentration of 15.7 µg mL- 1 for Streptococcus sanguinis and Aggregatibacter actinomycetemcomitans. The lipopeptide had no cytotoxic effect and demonstrated high potential application against bacterial biofilms.

Microbial Changes in the Periodontal Environment Due to Orthodontic Appliances: A Review

Orthodontic appliances significantly influence the microbiological dynamics within the oral cavity, transforming symbiotic relationships into dysbiotic states that can lead to periodontal diseases. This review synthesizes current findings on how orthodontic treatments, particularly fixed and removable appliances, foster niches for bacterial accumulation and complicate oral hygiene maintenance. Advanced culture-independent methods were employed to identify shifts toward anaerobic and pathogenic bacteria, with fixed appliances showing a more pronounced impact compared to clear aligners. The study underscores the importance of meticulous oral hygiene practices and routine dental monitoring to manage these microbial shifts effectively. By highlighting the relationship between appliance type, surface characteristics, treatment duration, and microbial changes, this review aims to enhance dental professionals' understanding of periodontal risks associated with orthodontic appliances and strategies to mitigate these risks. The findings are intended to guide clinicians in optimizing orthodontic care to prevent plaque-associated diseases, ensuring better periodontal health outcomes for patients undergoing orthodontic treatment.

Effect of perioperative oral care on postoperative infections in patients with cancer: A systematic review and meta-analysis

AIM

This systematic review aimed to assess the effect of non-pharmacologic perioperative oral hygiene care on reduced incidence of postoperative pneumonia (PP), surgical site infection (SSI), and the length of hospital stay in patients with cancer, and to describe the details of oral hygiene care.

METHODS

We searched seven databases. Eligibility criteria were based on perioperative oral hygiene care provided by healthcare professionals to patients aged ≥18 years who were surgically treated under general anesthesia and were evaluated for the incidence of PP and SSI. We reported risk ratios (RR) for dichotomous outcomes for PP and SSI using a fixed-effects model of meta-analysis.

RESULTS

The search resulted in 850 articles, among which two were randomized controlled trials (RCTs) and 21 were observational studies. Most studies indicated that dentists and medical care providers performed a combination of oral cleaning, and oral hygiene instructions. In RCTs, perioperative oral hygiene care significantly reduced the incidence of PP (RR, 0.86; p = .60), while in observational studies, perioperative oral hygiene care significantly reduced the incidence of PP (RR, 0.55; p < .001) and SSI (RR, 0.47; p < .001). The length of hospital stay was also significantly reduced (p < .05). However, the effectiveness of nursing intervention was not clear.

CONCLUSIONS

Perioperative oral hygiene care implemented by healthcare professionals prevented PP and SSI and reduced length of hospital stays for patients after cancer surgery. As daily perioperative oral hygiene care is performed by nurses, it is necessary to research the effects of oral hygiene by nurses in the future.

Bibliometric analysis of the association between periodontal disease and cardiovascular disease

Purpose

Conduct a bibliometric analysis to review the knowledge structure and research trends regarding the association between periodontal disease and cardiovascular disease (CVD).

Methods

The Web of Science Core collection database was searched for retrieving publications related to periodontitis and CVD between January 1, 2003 and December 31, 2022. The VOSviewer, CiteSpace, and R software package "bibliometrix" were employed for the bibliometric analysis.

Results

In total, 3447 articles were collected from 98 countries over the past 20 years, with the United States (1,003), Japan (377), and China (321) contributing the most publications. The literature in this field exhibited exponential growth. The University of Helsinki (n = 125, 1.37 %) holds the distinction of being the research institution with the highest number of publications, with a predominant representation from institutions in the United States. Notably, the Journal of Periodontology emerges as the most popular journal in the field, whereas the Journal of Clinical Periodontology takes the lead in terms of citations. These publications originated from 15,236 authors, with Pussinen (n = 40) having the highest number of published papers and Tonetti (n = 976) garnering the most citations. The visualization analysis of keywords identified "oral microbiome," "inflammation," and "porphyromonas gingivalis" as emerging research hotspots in exploring the relationship between periodontitis and CVDs.

Conclusion

Through a comprehensive bibliometric analysis, this study posits that periodontitis may heighten the risk of cardiovascular events, offering valuable academic references for scholars investigating the link between periodontitis and CVDs.

Association between oral frailty and Prevotella percentage in the oral microbiota of community-dwelling older adults who participated in the CHEER Iwamizawa project, Japan

BACKGROUND

Prevotella bacteria are associated with inherent diseases of the oral cavity, such as periodontal disease, and systemic diseases. Oral frailty (OF) has been associated with nursing necessity and death. However, the relationship between OF and oral microbiota has not been fully clarified.

OBJECTIVE

This cross-sectional study investigated the association between OF and Prevotella percentage in the oral microbiota of community-dwelling older adults.

METHODS

Oral bacteria species from saliva were identified in 208 community-dwelling older individuals aged ≥60 years in Japan. The proportion of Prevotella in the oral microbiota was classified into three tertile groups, and its relationship with each test item for OF (number of remaining teeth, masticatory performance, oral diadochokinesis, tongue pressure, difficulties eating tough foods, difficulties swallowing tea or soup, number of applicable OF judgement items, and existence of OF) was examined using ordinal logistic regression analysis.

RESULTS

The Prevotella proportions were classified into lower, middle and upper groups, comprising 70, 69 and 69 participants, respectively. The three groups showed a significant relationship between the number of remaining teeth (odds ratio [OR]: 0.946, 95% confidence interval [CI]: 0.915-0.977), masticatory performance (OR: 0.897, 95% CI: 0.844-0.953), number of applicable OF judgement items (OR: 1.477, 95% CI: 1.14-1.915), and existence of OF (OR: 4.194, 95% CI: 1.519-11.576).

CONCLUSION

The proportion of Prevotella in oral microbiota was high in individuals with OF. Among the older adults, the type of oral microbiota and systemic diseases may be related to the examination and management of oral function decline.

Impact of Pericoronary Microbiota Composition on Course of Recovery after Third Molar Alveotomy

Although the role of microbiota has been investigated in relation to different oral diseases, it is unknown if its composition has any effect on the course of recovery after third molar alveotomy. Our aim was to determine the influence of patient clinical characteristics as well as pericoronary microbiota composition on the course of recovery after a semi-impacted third molar alveotomy. Thirty-six patients were included and samples obtained with paper points, swabs, and tissue samples were analyzed using DNA hybridization and culture methods. Among the 295 organisms detected, the most frequent were Streptococcus spp. (22.4%; 66/295) followed by Fusobacterium spp. (11.9%; 35/295), and T. forsythia (9.1%; 27/295). A comparison of microbiota composition in patients with better and worse recovery did not show significant differences. Worse recovery outcomes were more frequent in patients with a grade 2 self-assessment of oral health (p = 0.040) and better recovery courses were observed in patients with a grade 4 self-assessment (p = 0.0200). A worse recovery course was statistically significant more frequently in patients with previous oral surgical procedures (p = 0.019). Although we demonstrate that worse recovery outcomes were more frequent when certain bacteria were detected, there was no statistically significant difference. Further research is needed to identify microbial profiles specific to the development of worse outcomes after a third molar alveotomy.

Characterization of the oral microbiota and the relationship of the oral microbiota with the dental and periodontal status in children and adolescents with nonsyndromic cleft lip and palate. Systematic literature review and meta-analysis

OBJECTIVE

To identify the characteristics of the oral microbiota and the relationship of the dental caries and periodontal status in patients aged 0 to 18 years with non-syndromic cleft lip and palate (CLP).

MATERIALS AND METHODS

A systematic review of the literature was carried out. Five databases were consulted, including publications in English, Spanish and Portuguese. The evaluations of the quality of the observational studies and the experimental studies were carried out with the Newcastle-Ottawa scale and CONSORT guidelines, respectively. The risk of bias of the studies was determined using Rev Manager 5.4, and 5 publications were meta-analyzed.

RESULTS

The cariogenic microbiota of children and adolescents with cleft lip and palate was similar to that of children without clefts, although with higher counts of Streptococcus mutans and Lactobacillus spp. The periodontopathogenic microbiota was related to the presence of Campylobacter spp, Fusobacterium spp, Fusobacterium nucleatum, Prevotella intermedia/nigrescens, Parvimonas micra and Porphyromonas gingivalis, considered microorganisms with high pathogenic capacity. Heterogeneity was shown in relation to the microbiota and the type of fissure, presenting numerous microorganisms associated with the pre- and post-surgical condition (cheilorrhaphy and palatorrhaphy) such as Staphylococcus aureus, Streptococcus beta hemolyticus, Klebsiella pneumoniae and Klebsiella oxytoca, Moraxella catarrhalis, Candida spp, Candida albicans, Candida krusei and Candida tropicalis. The meta-analysis revealed that patients with cleft lip and palate were 2.03 times more likely to have caries than the control group (p<0.005).

CONCLUSION

In the microbiota, there was a great diversity of microorganisms that can vary according to the type of fissure and surgical interventions predisposing patients to a greater probability of dental caries, it is important to take into account the technique used to describe the oral microbiota in order to be able to compare the different studies.

CLINICAL RELEVANCE

Studying the microbiota and the relationship of dental caries and periodontal status in children and adolescents with cleft lip and palate can facilitate the comprehensive care of patients with these conditions.

Role of Oral Microbiota Dysbiosis in the Development and Progression of Oral Lichen Planus

Oral lichen planus (OLP) is a chronic inflammatory autoimmune disease of the oral cavity with malignant potential affecting 1.01% of the worldwide population. The clinical patterns of this oral disorder, characterized by relapses and remissions of the lesions, appear on buccal, lingual, gingival, and labial mucosa causing a significant reduction in the quality of life. Currently, there are no specific treatments for this disease, and the available therapies with topical and systemic corticosteroids only reduce symptoms. Although the etiopathogenesis of this pathological condition has not been completely understood yet, several exogenous and endogenous risk factors have been proposed over the years. The present review article summarized the underlying mechanisms of action involved in the onset of OLP and the most well-known triggering factors. According to the current data, oral microbiota dysbiosis could represent a potential diagnostic biomarker for OLP. However, further studies should be undertaken to validate their use in clinical practice, as well as to provide a better understanding of mechanisms of action and develop novel effective intervention strategies against OLP.

Dental Health Benefits of Swimming in Chlorinated Water

Poor oral health is an important concern for athletes, as it can affect both general health and athletic performance. The aim of this study is to investigate the effects of activity in chlorinated water on oral health in elite swimmers compared to non-swimming athletes. This cross-sectional study included 101 swimmers and 100 other athletes aged 13-26 years with a minimum training intensity of five hours per week (for at least the preceding two years). Oral health was assessed using the approximal plaque index (API) and the decayed/missing/filled teeth (DMFT) index. A DIAGNOcam was used to detect caries. Results show that swimmers were younger (15 years vs. 18 years), were more likely to be female (54% vs. 17%), and had a lower body mass index (20.1 kg/m2 vs. 21.9 kg/m2) and a lower juice consumption (9% vs. 24%). Non-swimmers had significantly more decayed, missing, or filled teeth due to caries and plaque. In conclusion, by comparing elite swimmers and athletes competing in different sports, we have shown that competitive swimmers have a lower incidence of dental caries and plaque. Further research is needed to test our findings and to understand this relationship in greater detail.

Biological marker for the establishment of periodontal disease: cross-sectional study in the gingival tissue

BACKGROUND

The present study investigated the expression of COX-2, EMMPRIN, HIF-1α, and GLUT-1 in the gingival tissue to verify if there is a correlation between the immunoexpression of these proteins and the changes caused by the inflamed infiltrate present in the gingival tissues.

MATERIAL AND METHODS

A morphological analysis of epithelial changes (hyperplasia, exocytosis, spongiosis, and hydropic degeneration) was performed, as well as a semiquantitative analysis of the immunoexpression of COX-2, EMMPRIN, HIF-1α, and GLUT-1 in the epithelium and connective tissue of 60 specimens of gingival tissue.

RESULTS

Epithelial immunoexpression to COX-2 was observed in three cases, while EMMPRIN, HIF-1α, and GLUT-1 were strongly expressed in the basal layer of the epithelium and gradually decreased until the upper layers. In the connective tissue, COX-2 immunoexpression showed a statistically significant association (p < 0.001) with the gingival inflammatory infiltrate. In connective tissue, EMMPRIN and HIF-1α exhibited intense immunopositivity, while GLUT-1 was negative in most cases.

CONCLUSION

COX-2 expression may constitute a biological marker of gingival tissues since its epithelial immunoexpression may indicate a greater propensity for the establishment of periodontal disease.

Gut microbiota-gonadal axis: the impact of gut microbiota on reproductive functions

The influence of gut microbiota on physiological processes is rapidly gaining attention globally. Despite being under-studied, there are available data demonstrating a gut microbiota-gonadal cross-talk, and the importance of this axis in reproduction. This study reviews the impacts of gut microbiota on reproduction. In addition, the possible mechanisms by which gut microbiota modulates male and female reproduction are presented. Databases, including Embase, Google scholar, Pubmed/Medline, Scopus, and Web of Science, were explored using relevant key words. Findings showed that gut microbiota promotes gonadal functions by modulating the circulating levels of steroid sex hormones, insulin sensitivity, immune system, and gonadal microbiota. Gut microbiota also alters ROS generation and the activation of cytokine accumulation. In conclusion, available data demonstrate the existence of a gut microbiota-gonadal axis, and role of this axis on gonadal functions. However, majority of the data were compelling evidences from animal studies with a great dearth of human data. Therefore, human studies validating the reports of experimental studies using animal models are important.

Evaluation of the ceramic laminate veneer-tooth interface after different resin cement excess removal techniques

OBJECTIVES

To compare, in vitro, resin cement excess removal techniques at the veneer-tooth interface.

MATERIALS AND METHODS

Anterior human teeth were restored with ceramic veneers and randomly divided according to the following techniques (n = 10): removal of excess resin cement with brush and dental floss, followed by light-curing with Valo (Group 1) or Elipar (Group 2) for 1 min and 40 s; tack-curing with Valo (Group 3) or Elipar (Group 4) for 1 s; and tack-curing with Valo (Group 5) or Elipar (Group 6) for 5 s. The tack-curing was followed by removal of excess with probe and dental floss and light-curing for 1 min and 40 s. The area of excess resin cement (mm2) was measured in micro-CT images using AutoCAD program. The failures at the cervical margin in the X, Y, and Z axes (µm) of greater value were measured using the DataViewer program. The specimens were submitted to microleakage with 2% basic fuchsin.

RESULTS

According to the Kruskal-Wallis and multiple comparison test, the highest area of excess resin cement was found in Group 1 (5.06 mm2), which did not differ statistically from Groups 2 (3.70 mm2) and 5 (2.19 mm2). Groups 2, 3 (1.73 mm2), 4 (1.14 mm2), and 5 (2.18 mm2) did not differ statistically. Group 6 (0.77 mm2) obtained the lowest value, which did not differ statistically from Groups 3 and 4. According to the Kruskal-Wallis and Dunn test, there was no significant difference in failures in X (p = 0.981), Y (p = 0.860), and Z (p = 0.638) axes and no significant difference in microleakage (p = 0.203) among the groups.

CONCLUSIONS

Tack-curing for 1 s or 5 s, followed by removal of excess resin cement using a probe and a dental floss, tended to result in a lower amount of excess material around the margin.

CLINICAL RELEVANCE

The technique used for resin cement excess removal influences the amount of excess leaved at the veneer-tooth interface. Tack-curing for 1 s or 5 s is recommended to mitigate the excess resin cement.

MicroRNA-146a-loaded magnesium silicate nanospheres promote bone regeneration in an inflammatory microenvironment

Reconstruction of irregular oral-maxillofacial bone defects with an inflammatory microenvironment remains a challenge, as chronic local inflammation can largely impair bone healing. Here, we used magnesium silicate nanospheres (MSNs) to load microRNA-146a-5p (miR-146a) to fabricate a nanobiomaterial, MSN+miR-146a, which showed synergistic promoting effects on the osteogenic differentiation of human dental pulp stem cells (hDPSCs). In addition, miR-146a exhibited an anti-inflammatory effect on mouse bone marrow-derived macrophages (BMMs) under lipopolysaccharide (LPS) stimulation by inhibiting the NF-κB pathway via targeting tumor necrosis factor receptor-associated factor 6 (TRAF6), and MSNs could simultaneously promote M2 polarization of BMMs. MiR-146a was also found to inhibit osteoclast formation. Finally, the dual osteogenic-promoting and immunoregulatory effects of MSN+miR-146a were further validated in a stimulated infected mouse mandibular bone defect model via delivery by a photocuring hydrogel. Collectively, the MSN+miR-146a complex revealed good potential in treating inflammatory irregular oral-maxillofacial bone defects.

Dental Caries: Unveiling the State-of-the-art Insights and Crafting Hypotheses for Oral Health

The pathophysiological understanding of dental caries explains that the primary factor responsible is linked to an imbalance in microbial composition within the oral cavity, stemming from both artificial and natural sources. Streptococcus mutans (S. mutans) is the most accountable and prevalent pathogen for caries development among the diverse pool. S. mutans, an acidogenic bacterium, lowers oral pH through the metabolic conversion of dietary sugar into organic acids, leading to enamel demineralization and dental caries. Numerous antibacterial interventions have been employed in the past to address this issue. However, adopting such an approach poses the risk of exacerbating concerns related to Antimicrobial Resistance (AMR) and long-term oral cytotoxicity. In response to this, a sustainable strategy is suggested, involving the utilization of L-Arginine (L-Arg) as a probiotic nutrient supplement for non-pathogenic microbes. It will help in creating a natural competitive environment against the pathogenic microbes responsible for initiating dental caries. The hypothesis involves utilizing a combination of a nutrient supplement and the repurposed drug Piceatannol, specifically for its anti-biofilm properties. This combination synergistically improves the effectiveness of the therapy by converting the complex microbial biofilm into a planktonic state.

Antibacterial properties and abrasion-stability: Development of a novel silver-compound material for orthodontic bracket application

PURPOSE

Bacteria-induced white spot lesions are a common side effect of modern orthodontic treatment. Therefore, there is a need for novel orthodontic bracket materials with antibacterial properties that also resist long-term abrasion. The aim of this study was to investigate the abrasion-stable antibacterial properties of a newly developed, thoroughly silver-infiltrated material for orthodontic bracket application in an in situ experiment.

METHODS

To generate the novel material, silver was vacuum-infiltrated into a sintered porous tungsten matrix. A tooth brushing simulation machine was used to perform abrasion equal to 2 years of tooth brushing. The material was characterized by energy dispersive X‑ray (EDX) analysis and roughness measurement. To test for antibacterial properties in situ, individual occlusal splints equipped with specimens were worn intraorally by 12 periodontal healthy patients for 48 h. After fluorescence staining, the quantitative biofilm volume and live/dead distribution of the initial biofilm formation were analyzed by confocal laser scanning microscopy (CLSM).

RESULTS

Silver was infiltrated homogeneously throughout the tungsten matrix. Toothbrush abrasion only slightly reduced the material's thickness similar to conventional stainless steel bracket material and did not alter surface roughness. The new silver-modified material showed significantly reduced biofilm accumulation in situ. The effect was maintained even after abrasion.

CONCLUSION

A promising, novel silver-infiltrated abrasion-stable material for use as orthodontic brackets, which also exhibit strong antibacterial properties on in situ grown oral biofilms, was developed. The strong antibacterial properties were maintained even after surface abrasion simulated with long-term toothbrushing.

Antibacterial Effects of Silver Diamine Fluoride with and without Potassium Iodide against Streptococcus mutans

Introduction

Silver diamine fluoride (SDF) is a topical treatment for carious lesions and a primary preventative for newly exposed high-risk surfaces such as fissures and roots in the first molars. Using potassium iodide (KI) after applying SDF has been recommended as a way of reducing the severity of black staining, as well as preserving its antibacterial effect useful in deep caries.

Objective

The objective of this research was to compare the antibacterial effect of SDF, with and without KI, on Streptococcus mutans (S. mutans) and dental biofilm.

Methods

The antibacterial effects of SDF, KI, and the combination of both were measured using three different techniques (inhibition halo, minimum inhibitory effect [MIE], and colony-forming unit [CFU], testing).

Results

The results were then subjected to statistical analysis. Analyzed by means of the Kruskal-Wallis statistical test, the inhibition halos yielded a value of P = 0.3309. Using the MIE test, only the SDF treatment produced an antibacterial effect, at 10%, compared to the KI group, with P = 0.001. Finally, the CFU test revealed a total absence of colonies for all three reagents. All three substances analyzed achieved total inhibition of S. mutans. SDF is effective even in its minimal commercial concentration. Its antibacterial capacity decreases with the addition of KI.

Conclusions

The three substances analyzed at their maximum concentrations exhibited an antibacterial effect against S. mutans, resulting in total inhibition.

The contribution of maternal factors to the oral microbiota of the child: Influence from early life and clinical relevance

The mother represents one of the earliest sources of microorganisms to the child, influencing the acquisition and establishment of its microbiota in early life. However, the impact of the mother on the oral microbiota of the child from early life until adulthood remains to unveil. This narrative review aims to: i) explore the maternal influence on the oral microbiota of the child, ii) summarize the similarity between the oral microbiota of mother and child over time, iii) understand possible routes for vertical transmission, and iv) comprehend the clinical significance of this process for the child. We first describe the acquisition of the oral microbiota of the child and maternal factors related to this process. We compare the similarity between the oral microbiota of mother and child throughout time, while presenting possible routes for vertical transmission. Finally, we discuss the clinical relevance of the mother in the pathophysiological outcome of the child. Overall, maternal and non-maternal factors impact the oral microbiota of the child through several mechanisms, although the consequences in the long term are still unclear. More longitudinal research is needed to unveil the importance of early-life microbiota on the future health of the infant.

In Vitro Eradication of Planktonic, Saliva and Biofilm Bacteria Using Lingonberry Extract as a Photosensitizer for Visible Light Plus Water-Filtered Infrared-A Irradiation

Antimicrobial photodynamic treatment (aPDT) with visible light plus water-filtered infrared-A irradiation (VIS-wIRA) and natural single- or multi-component photosensitizers (PSs) was shown to have potent antimicrobial activity. The aim of this study was to obtain information on the antimicrobial effects of aPDT-VIS-wIRA with lingonberry extract (LE) against bacteria that play a role in oral health. Planktonic bacterial cultures of the Gram-positive E. faecalis T9, S. mutans DSM20523, S. oralis ATCC 35037 and S. sobrinus PSM 203513, the Gram-negative N. oralis 14F2 FG-15-7B, F. nucleatum ATCC 25586, and V. parvula DSM, the anaerobic F. nucleatum ATCC 25586 and V. parvula DSM 2008, and the total mixed bacteria from pooled saliva and supra- and subgingival plaques of volunteers were all treated and compared. aPDT-VIS-wIRA with LE as PS significantly (p < 0.008) reduced the growth of all tested Gram-positive, Gram-negative, as well as aerobic and anaerobic bacterial strains, whereas without irradiation no reductions were seen (p < 0.0001). NaCl, with or without irradiation, was ineffective. After treatment with CHX 0.2%, the highest killing rate (100%) was observed, and no bacteria (0 log10 CFU) were cultivable. The method also significantly reduced all of the bacteria present in saliva and in the gingival biofilms. Three-dimensional visualization of viable and non-viable microorganisms revealed that LE penetrated deeper into the cell wall layers than CHX 0.2%. LE was an appropriate PS for eradicating microorganisms with VIS-wIRA, either in their planktonic form or in saliva and gingival plaque biofilms. These results encourage further investigation in order to determine which LE compounds contribute to the photosensitizing effect and to evaluate the size of the effect on maintaining oral health.

Oral microbiota analyses of paediatric Saudi population reveals signatures of dental caries

BACKGROUND

Oral microbiome sequencing has revealed key links between microbiome dysfunction and dental caries. However, these efforts have largely focused on Western populations, with few studies on the Middle Eastern communities. The current study aimed to identify the composition and abundance of the oral microbiota in saliva samples of children with different caries levels using machine learning approaches.

METHODS

Oral microbiota composition and abundance were identified in 250 Saudi participants with high dental caries and 150 with low dental caries using 16 S rRNA sequencing on a NextSeq 2000 SP flow cell (Illumina, CA) using 250 bp paired-end reads, and attempted to build a classifier using random forest models to assist in the early detection of caries.

RESULTS

The ADONIS test results indicate that there was no significant association between sex and Bray-Curtis dissimilarity (p ~ 0.93), but there was a significant association with dental caries status (p ~ 0.001). Using an alpha level of 0.05, five differentially abundant operational taxonomic units (OTUs) were identified between males and females as the main effect along with four differentially abundant OTUs between high and low dental caries. The mean metrics for the optimal hyperparameter combination using the model with only differentially abundant OTUs were: Accuracy (0.701); Matthew's correlation coefficient (0.0509); AUC (0.517) and F1 score (0.821) while the mean metrics for random forest model using all OTUs were:0.675; 0.054; 0.611 and 0.796 respectively.

CONCLUSION

The assessment of oral microbiota samples in a representative Saudi Arabian population for high and low metrics of dental caries yields signatures of abundances and diversity.

Fecal microbiota as a predictor of acupuncture responses in patients with postpartum depressive disorder

Background

There are several clinical and molecular predictors of responses to antidepressant therapy. However, these markers are either too subjective or complex for clinical use. The gut microbiota could provide an easily accessible set of biomarkers to predict therapeutic efficacy, but its value in predicting therapy responses to acupuncture in patients with depression is unknown. Here we analyzed the predictive value of the gut microbiota in patients with postpartum depressive disorder (PPD) treated with acupuncture.

Methods

Seventy-nine PPD patients were enrolled: 55 were treated with acupuncture and 24 did not received any treatment. The 17-item Hamilton depression rating scale (HAMD-17) was used to assess patients at baseline and after eight weeks. Patients receiving acupuncture treatment were divided into an acupuncture-responsive group or non-responsive group according to HAMD-17 scores changes. Baseline fecal samples were obtained from the patients receiving acupuncture and were analyzed by high-throughput 16S ribosomal RNA sequencing to characterize the gut microbiome.

Results

47.27% patients responded to acupuncture treatment and 12.5% patients with no treatment recovered after 8-week follow-up. There was no significant difference in α-diversity between responders and non-responders. The β-diversity of non-responders was significantly higher than responders. Paraprevotella and Desulfovibrio spp. were significantly enriched in acupuncture responders, and these organisms had an area under the curve of 0.76 and 0.66 for predicting responder patients, respectively.

Conclusions

Paraprevotella and Desulfovibrioare may be useful predictive biomarkers to predict PPD patients likely to respond to acupuncture. Larger studies and validation in independent cohorts are now needed to validate our findings.

The Interaction between the Oral Microbiome and Systemic Diseases: A Narrative Review

Background: The human being is defined as a ‘superorganism’ since it is made up of its own cells and microorganisms that reside inside and outside the human body. Commensal microorganisms, which are even ten times more numerous than the cells present in the body, perform very important functions for the host, as they contribute to the health of the host, resist pathogens, maintain homeostasis, and modulate the immune system. In the mouth, there are different types of microorganisms, such as viruses, mycoplasmas, bacteria, archaea, fungi, and protozoa, often organized in communities. The aim of this umbrella review is to evaluate if there is a connection between the oral microbiome and systematic diseases. Methodology: A literature search was conducted through PubMed/MEDLINE, the COCHRANE library, Scopus, and Web of Science databases without any restrictions. Because of the large number of articles included and the wide range of methods and results among the studies found, it was not possible to report the results in the form of a systematic review or meta-analysis. Therefore, a narrative review was conducted. We obtained 73.931 results, of which 3593 passed the English language filter. After the screening of the titles and abstracts, non-topic entries were excluded, but most articles obtained concerned interactions between the oral microbiome and systemic diseases. Discussion: A description of the normal microbial flora was present in the oral cavity both in physiological conditions and in local pathological conditions and in the most widespread systemic pathologies. Furthermore, the therapeutic precautions that the clinician can follow in order to intervene on the change in the microbiome have been described. Conclusions: This review highlights what are the intercorrelations of the oral microbiota in healthy subjects and in subjects in pathological conditions. According to several recent studies, there is a clear correlation between dysbiosis of the oral microbiota and diseases such as diabetes, cardiovascular diseases, chronic inflammatory diseases, and neurodegenerative diseases.

Effect of build angle, resin layer thickness and viscosity on the surface properties and microbial adhesion of denture bases manufactured using digital light processing

OBJECTIVES

To investigate differences in the surface properties and microbial adhesion of denture base resins for digital light processing (DLP) with varying resin layer thicknesses (LT), build angles (BA), and resin viscosities.

METHODS

Two denture base resins for DLP with different viscosities (high and low) were used to prepare disk specimens applying two manufacturing parameters: 1) LT (50 or 100 μm) and 2) BA (0-, 45-, and 90-degree). Surface roughness and contact angle values were measured on the test surfaces (n=10 per group). Streptococcus oralis and Candida albicans absorbance was measured to assess microorganism attachment (n=6 per group). A three-way analysis of variance (ANOVA) was conducted, considering the main effects and their interactions (viscosity, LT, and BA). Post-hoc multiple pairwise comparisons were performed. All data were analyzed at a level of significance (P) of 0.05.

RESULTS

LT and BA significantly affected the surface roughness and contact angle of the specimens, depending on resin viscosity (P<.001). Absorbance measurement showed no significant interaction between the three factors (P>.05). However, significant interactions were observed between viscosity and BA (P<.05) and between LT and BA (P<.05).

CONCLUSIONS

Regardless of the viscosity and LT, discs with a 0-degree BA showed the least roughness. High-viscosity specimens fabricated with a 0-degree BA had the lowest contact angle. Regardless of the LT and viscosity, discs with a 0-degree BA showed the lowest S. oralis attachment. Attachment of C. albicans was the least on the disk with 50 μm LT, irrespective of the viscosity.

CLINICAL SIGNIFICANCE

Clinicians should consider the effects of LT and BA on surface roughness, contact angle, and microbial adhesion of DLP-generated dentures, which can differ depending on resin viscosity. A 50 μm LT and 0-degree BA can be used with a high-viscosity resin to fabricate denture bases with less microbial adhesion.

Polyalthic Acid from Copaifera lucens Demonstrates Anticariogenic and Antiparasitic Properties for Safe Use

This study aimed at evaluating the potential of Copaifera lucens, specifically its oleoresin (CLO), extract (CECL), and the compound ent-polyalthic acid (PA), in combating caries and toxoplasmosis, while also assessing its toxicity. The study involved multiple assessments, including determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against cariogenic bacteria. CLO and PA exhibited MIC and MBC values ranging from 25 to 50 μg/mL, whereas CECL showed values equal to or exceeding 400 μg/mL. PA also displayed antibiofilm activity with minimum inhibitory concentration of biofilm (MICB50) values spanning from 62.5 to 1000 μg/mL. Moreover, PA effectively hindered the intracellular proliferation of Toxoplasma gondii at 64 μg/mL, even after 24 h without treatment. Toxicological evaluations included in vitro tests on V79 cells, where concentrations ranged from 78.1 to 1250 μg/mL of PA reduced colony formation. Additionally, using the Caenorhabditis elegans model, the lethal concentration (LC50) of PA was determined as 1000 μg/mL after 48 h of incubation. Notably, no significant differences in micronucleus induction and the NDI were observed in cultures treated with 10, 20, or 40 μg/mL of CLO. These findings underscore the safety profile of CLO and PA, highlighting their potential as alternative treatments for caries and toxoplasmosis.

The increasing importance of the oral microbiome in periodontal health and disease

Herein, the aim is to discuss the current knowledge of microbiome and periodontal diseases. Current treatment strategies include mechanical therapy such as root planing, scaling, deep pocket debridement and antimicrobial chemotherapy as an adjuvant therapy. Among promising therapeutic strategies, dental probiotics and oral microbiome transplantation have gained attention, and may be used to treat bacterial imbalances by competing with pathogenic bacteria for nutrients and adhesion surfaces, as well as probiotics targeting the gut microbiome. Development of strategies to prevent and treat periodontal diseases are warranted as both are highly prevalent and can affect human health. Further studies are necessary to better comprehend the microbiome in order to develop innovative preventative measures as well as efficacious therapies against periodontal diseases.

Screening of heat-killed lactic acid bacteria based on inhibitory activity against oral bacteria and effects of oral administration of heat-killed Ligilactobacillus salivarius CP3365 on periodontal health in healthy participants: a double-blinded, randomized, placebo-controlled trial

Objectives

The aims of this study were to select heat-killed lactic acid bacteria (HKL) with antibiotic activity and investigate the efficacy of this bacteria in maintaining periodontal parameters in healthy participants.

Materials and methods

An in vitro evaluation was conducted to assess the inhibitory efficacy of lactic acid bacteria against Porphyromonas gingivalis and Fusobacterium nucleatum subsp. nucleatum. The effects of HKL administration on various parameters (plaque control record, bleeding on probing, and probing pocket depth) were assessed in a randomized, placebo-controlled trial. Participants in the test and placebo groups (n = 32) consumed oral tablets containing placebo or HKL daily for 8 weeks. Oral bacteria in supra-plaque and saliva were identified using 16S rRNA gene community profiling analysis.

Results

Heat-killed Ligilactobacillus salivarius CP3365 significantly (p < 0.05) decreased the viability of oral bacteria and was selected for clinical trials. Administration of HKL CP3365 significantly (p < 0.05) inhibited increases in each parameter. No changes in the relative abundance of P. gingivalis or F. nucleatum subsp. nucleatum were detected by HKL CP3365, but the relative abundance of oral bacteria (genera Porphyromonas, Fusobacterium, and Haemophilus) was significantly (p < 0.05) decreased.

Conclusion

HKL CP3365 effectively inhibited oral bacteria growth and was useful for maintaining periodontal health.

Clinical Trial Registration

[https://www.umin.ac.jp/ctr/index.htm], identifier [UMIN000045656].

The role of Actinomyces spp. and related organisms in cervicofacial infections: Pathomechanism, diagnosis and therapeutic aspects

Members of the Actinomyces genus and Actinomyces-like organisms (ALOs; namely Actinotignum, Arcanobacterium, Schaalia and Varibaculum) are Gram-positive, non-spore-forming rods that are commensal members of the human oral cavity, gastrointestinal tract, female genital tract and skin microbiota. Cervicofacial actinomycosis or "lumpy jaw syndrome" - the chronic, suppurative granulomatous disease caused by Actinomyces spp. And ALOs - is characterized by an initially slow and unspecific disease-presentation, which often mimics other pathologies, followed by the formation of painful abscesses and severe tissue destruction. Actinomycosis has been described as a rare disease, however, reliable epidemiological data are lacking. In addition, there is increasing awareness regarding the role of Actinomyces spp. in the development of osteoradionecrosis and medication-related osteonecrosis of the jaw. The aim of this narrative review is to succinctly summarize the current advances regarding the microbiological, clinical, diagnostic and therapeutic aspects of cervicofacial actinomycosis, in addition to the roles of Actinomyces species and ALOs as members of the oral microbiota and in dental biofilm, in other dental infections (caries, root canal infection, periapical infection, periodontitis) and osteonecrosis of the jaw, in the context of recent taxonomic changes affecting the genus. Our paper aims to be a blueprint for dentists, other physicians, microbiologists and researchers regarding the multifaceted field of cervicofacial actinomycosis.

Predicting potential microbe-disease associations based on multi-source features and deep learning

Studies have confirmed that the occurrence of many complex diseases in the human body is closely related to the microbial community, and microbes can affect tumorigenesis and metastasis by regulating the tumor microenvironment. However, there are still large gaps in the clinical observation of the microbiota in disease. Although biological experiments are accurate in identifying disease-associated microbes, they are also time-consuming and expensive. The computational models for effective identification of diseases related microbes can shorten this process, and reduce capital and time costs. Based on this, in the paper, a model named DSAE_RF is presented to predict latent microbe-disease associations by combining multi-source features and deep learning. DSAE_RF calculates four similarities between microbes and diseases, which are then used as feature vectors for the disease-microbe pairs. Later, reliable negative samples are screened by k-means clustering, and a deep sparse autoencoder neural network is further used to extract effective features of the disease-microbe pairs. In this foundation, a random forest classifier is presented to predict the associations between microbes and diseases. To assess the performance of the model in this paper, 10-fold cross-validation is implemented on the same dataset. As a result, the AUC and AUPR of the model are 0.9448 and 0.9431, respectively. Furthermore, we also conduct a variety of experiments, including comparison of negative sample selection methods, comparison with different models and classifiers, Kolmogorov-Smirnov test and t-test, ablation experiments, robustness analysis, and case studies on Covid-19 and colorectal cancer. The results fully demonstrate the reliability and availability of our model.

A preliminary study of the salivary microbiota of young male subjects before, during, and after acute high-altitude exposure

Background

The microbial community structure in saliva differs at different altitudes. However, the impact of acute high-altitude exposure on the oral microbiota is unclear. This study explored the impact of acute high-altitude exposure on the salivary microbiome to establish a foundation for the future prevention of oral diseases. Methods. Unstimulated whole saliva samples were collected from 12 male subjects at the following three time points: one day before entering high altitude (an altitude of 350 m, pre-altitude group), seven days after arrival at high altitude (an altitude of 4,500 m, altitude group) and seven days after returning to low altitude (an altitude of 350 m, post-altitude group). Thus, a total of 36 saliva samples were obtained. 16S rRNA V3-V4 region amplicon sequencing was used to analyze the diversity and structure of the salivary microbial communities, and a network analysis was employed to investigate the relationships among salivary microorganisms. The function of these microorganisms was predicted with a Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis.

Results

In total, there were 756 operational taxonomic units (OTUs) identified, with 541, 613, and 615 OTUs identified in the pre-altitude, altitude, and post-altitude groups, respectively. Acute high-altitude exposure decreased the diversity of the salivary microbiome. Prior to acute high-altitude exposure, the microbiome mainly consisted of Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Actinobacteria. After altitude exposure, the relative abundance of Streptococcus and Veillonella increased, and the relative abundance of Prevotella, Porphyromonas, and Alloprevotella decreased. The relationship among the salivary microorganisms was also affected by acute high-altitude exposure. The relative abundance of carbohydrate metabolism gene functions was upregulated, while the relative abundance of coenzyme and vitamin metabolism gene functions was downregulated.

Conclusion

Rapid high-altitude exposure decreased the biodiversity of the salivary microbiome, changing the community structure, symbiotic relationships among species, and abundance of functional genes. This suggests that the stress of acute high-altitude exposure influenced the stability of the salivary microbiome.

Root Canal Infection and Its Impact on the Oral Cavity Microenvironment in the Context of Immune System Disorders in Selected Diseases: A Narrative Review

The oral cavity has a specific microenvironment, and structures such as teeth are constantly exposed to chemical and biological factors. Although the structure of the teeth is permanent, due to exposure of the pulp and root canal system, trauma can have severe consequences and cause the development of local inflammation caused by external and opportunistic pathogens. Long-term inflammation can affect not only the local pulp and periodontal tissues but also the functioning of the immune system, which can trigger a systemic reaction. This literature review presents the current knowledge on root canal infections and their impact on the oral microenvironment in the context of immune system disorders in selected diseases. The result of the analysis of the literature is the statement that periodontal-disease-caused inflammation in the oral cavity may affect the development and progression of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, or Sjogren's syndrome, as well as affecting the faster progression of conditions in which inflammation occurs such as, among others, chronic kidney disease or inflammatory bowel disease.

Bactericidal Activity of Silver Nanoparticles on Oral Biofilms Related to Patients with and without Periodontal Disease

BACKGROUND AND OBJECTIVES

Periodontal disease (PD) is a multifactorial oral disease regularly caused by bacterial biofilms. Silver nanoparticles (AgNP) have offered good antimicrobial activity; moreover, there is no available scientific information related to their antimicrobial effects in biofilms from patients with PD. This study reports the bactericidal activity of AgNP against oral biofilms related to PD.

MATERIALS AND METHODS

AgNP of two average particle sizes were prepared and characterized. Sixty biofilms were collected from patients with (30 subjects) and without PD (30 subjects). Minimal inhibitory concentrations of AgNP were calculated and the distribution of bacterial species was defined by polymerase chain reaction.

RESULTS

Well-dispersed sizes of AgNP were obtained (5.4 ± 1.3 and 17.5 ± 3.4 nm) with an adequate electrical stability (-38.2 ± 5.8 and -32.6 ± 5.4 mV, respectively). AgNP showed antimicrobial activities for all oral samples; however, the smaller AgNP had significantly the most increased bactericidal effects (71.7 ± 39.1 µg/mL). The most resistant bacteria were found in biofilms from PD subjects (p < 0.05). P. gingivalis, T. denticola, and T. forsythia were present in all PD biofilms (100%).

CONCLUSIONS

The AgNP showed efficient bactericidal properties as an alternative therapy for the control or progression of PD.

Possible Therapeutic Mechanisms and Future Perspectives of Vaginal Microbiota Transplantation

Microbial communities inhabiting the human body play a crucial role in protecting the host against pathogens and inflammation. Disruptions to the microbial composition can lead to various health issues. Microbial transfer therapy (MTT) has emerged as a potential treatment option to address such issues. Fecal microbiota transplantation (FMT) is the most widely used form of MTT and has been successful in treating several diseases. Another form of MTT is vaginal microbiota transplantation (VMT), which involves transferring vaginal microbiota from a healthy female donor to a diseased patient's vaginal cavity with the goal of restoring normal vaginal microbial composition. However, VMT has not been extensively studied due to safety concerns and a lack of research. This paper explores the therapeutic mechanisms of VMT and discusses future perspectives. Further research is necessary to advance the clinical applications and techniques of VMT.

Interactions between systemic diseases and oral microbiota shifts in the aging community: A narrative review

As a gateway to general health and a diverse microbial habitat, the oral cavity is colonized by numerous microorganisms such as bacteria, fungi, viruses, and archaea. Oral microbiota plays an essential role in preserving oral health. Besides, the oral cavity also significantly contributes to systemic health. Physiological aging influences all body systems, including the oral microbial inhabitants. The cited effect can cause diseases by forming dysbiotic communities. Since it has been demonstrated that microbial dysbiosis could disturb the symbiosis state between the host and the resident microorganism, shifting the condition toward a more pathogenic one, this study investigated how the oral microbial shifts in aging could associate with the development or progression of systemic diseases in older adults. The current study focused on the interactions between variations in the oral microbiome and prevalent diseases in older adults, including diabetes mellitus, Sjögren's syndrome, rheumatoid arthritis, pulmonary diseases, cardiovascular diseases, oral candidiasis, Parkinson's disease, Alzheimer's disease, and glaucoma. Underlying diseases can dynamically modify the oral ecology and the composition of its resident oral microbiome. Clinical, experimental, and epidemiological research suggests the associations of systemic disorders with bacteremia and inflammation after oral microbial changes in older adults.