Changes in salivary microbiota increase volatile sulfur compounds production in healthy male subjects with academic-related chronic stress

Dynamic Human Gut Microbiome and Immune Shifts During an Immersive Psychosocial Therapeutic Program

Background

Depression is a leading cause of disability worldwide yet its underlying factors, particularly microbial associations, are poorly understood.

Methods

We examined the longitudinal interplay between the microbiome and immune system in the context of depression during an immersive psychosocial intervention. 142 multi-omics samples were collected from 52 well-characterized participants before, during, and three months after a nine-day inquiry-based stress reduction program.

Results

We found that depression was associated with both an increased presence of putatively pathogenic bacteria and reduced microbial beta-diversity. Following the intervention, we observed reductions in neuroinflammatory cytokines and improvements in several mental health indicators. Interestingly, participants with a Prevotella-dominant microbiome showed milder symptoms when depressed, along with a more resilient microbiome and more favorable inflammatory cytokine profile, including reduced levels of CXCL-1.

Conclusions

Our findings reveal a protective link between the Prevotella-dominant microbiome and depression, associated with a less inflammatory environment and moderated symptoms. These insights, coupled with observed improvements in neuroinflammatory markers and mental health from the intervention, highlight potential avenues for microbiome-targeted therapies in depression management.

Phyllanthus emblica fruit extract alleviates halitosis and reduces the inflammatory response to oral bacteria

OBJECTIVE

To assess the efficacy of Phyllanthus emblica extract in alleviating halitosis and reducing the inflammatory response to halitosis-related bacteria.

METHODOLOGY

This investigation, using Phyllanthus emblica fruit extract (PE), involved four aspects. First, we evaluated the effect on growth and aggregation of halitosis-related bacteria, including Fusobacterium nucleatum, Porphyromonas gingivalis, and Solobacterium moorei, using a microdilution assay and scanning electron microscopy. Second, volatile sulfur compound (VSC) levels were measured on individuals with halitosis in randomized short-term (26 participants) and double-blind randomized long-term trials (18 participants in each group) after rinsing with PE for 3, 6, and 12 h, and 28 days. Third, we analyzed pro-inflammatory cytokine expression in TR146 cells using quantitative real-time PCR and enzyme-linked immunosorbent assays. Lastly, we assessed pro-inflammatory cytokine secretion and Toll-like receptor (TLR) 2 mRNA expression via the same experimental methods in a three-dimensional oral mucosal epithelial model (3D OMEM).

RESULTS

PE extract dose-dependently inhibited the growth of F. nucleatum (50% inhibition concentration [IC50]=0.079%), P. gingivalis (IC50=0.65%), and S. moorei (IC50=0.07%) and effectively prevented bacterial aggregation. Furthermore, VSC contents decreased significantly at 3, 6, and 12 h after rinsing with 5% PE compared with those in the control. Long-term use of mouthwash containing 5% PE for 28 days led to a significant decrease in VSC contents. PE attenuated the F. nucleatum- or P. gingivalis-stimulated mRNA expression and protein release of interleukin (IL)-6 and IL-8 in TR146 cells. It also suppressed IL-8 and prostaglandin E2 secretion and TLR2 mRNA expression in F. nucleatum-induced OMEMs.

CONCLUSION

Our findings support the use of PE in oral care products to alleviate halitosis and it may reduce inflammation.

Oral Microbiota Populations of Adult Dogs Consuming Wet or Dry Foods

Oral microbiota play a prominent role in canine periodontal disease and wet foods are often blamed for poor oral health, but canine oral microbial communities have been poorly studied. We aimed to determine differences in oral health measures, breath odor, and oral microbiota populations of dogs fed wet or dry food. Twelve adult dogs fed either a commercial dry (extruded) or commercial wet (canned) food for 6 wk were studied. Breath samples were measured for sulfur compounds, teeth were scored for plaque, calculus, and gingivitis by a blinded veterinary dentist, salivary pH was measured, and supragingival (SUP) and subgingival (SUB) plaque samples were collected for microbiota analysis. Plaque DNA was extracted and Illumina sequencing conducted. Phylogenetic data were analyzed using the CosmosID bioinformatics platform and SAS 9.4, with P<0.05 being significant and P<0.10 being trends. Plaque coverage tended to be higher (P<0.10) in dogs fed wet vs. dry food, but other oral health scores were not different. Dogs fed dry food had higher (P<0.05) salivary pH and lower (P<0.05) breath sulfur concentrations than those consuming wet food. Bacterial alpha diversity was higher in SUP than SUB samples, and a clear separation in beta diversity was observed between sample sites on principal coordinates analysis (PCoA) plots. In SUP samples, dogs fed wet food had a higher alpha diversity than dogs fed dry food, with PCoA plots showing a separation between wet and dry food. Relative abundances of Firmicutes, Synergistetes, and 10 bacterial genera were different (P<0.05) in SUB samples of dogs fed wet vs. dry food. Relative abundances of Fusobacteria and over 20 bacterial genera were different (P<0.05) in SUP samples of dogs fed wet vs. dry food. In general, oral health-associated bacterial taxa (Pasteurella, Capnocytophaga, Corynebacterium) were higher, while bacteria associated with poor oral health (Fretibacterium fastidiosum, Filifactor alocis, Treponema medium, Tannerella forsythia, Porphyromonas canoris, Porphyromonas gingivalis) were lower in dogs fed dry food. Such shifts in the oral microbiota may impact periodontal disease risk, but longer dietary intervention studies are required to confirm their role in the disease process. Our results suggest that dogs fed dry extruded foods have lower breath odor and tooth plaque buildup and an oral microbiota population more closely associated with oral health than dogs fed wet canned foods.

More Than Just a Periodontal Pathogen –the Research Progress on Fusobacterium nucleatum

Fusobacterium nucleatum is a common oral opportunistic bacterium that can cause different infections. In recent years, studies have shown that F. nucleatum is enriched in lesions in periodontal diseases, halitosis, dental pulp infection, oral cancer, and systemic diseases. Hence, it can promote the development and/or progression of these conditions. The current study aimed to assess research progress in the epidemiological evidence, possible pathogenic mechanisms, and treatment methods of F. nucleatum in oral and systemic diseases. Novel viewpoints obtained in recent studies can provide knowledge about the role of F. nucleatum in hosts and a basis for identifying new methods for the diagnosis and treatment of F. nucleatum-related diseases.

Relationships between Solobacterium moorei and Prevotella intermedia in subgingival microbiota of periodontitis patients with halitosis: A preliminary study using qPCR

Objective

Material & methods

Results

Conclusion

A fecal-based test for the detection of advanced adenoma and colorectal cancer: a case-control and screening cohort study

BACKGROUND

Colorectal cancer (CRC) is the leading cause of cancer death worldwide. Screening is a confirmed way to reduce the incidence and mortality rates of CRC. This study aimed to identify a fecal-based, noninvasive, and accurate method for detection of colorectal cancer (CRC) and advanced adenoma (AA).

METHODS

Through detection in tissue (n = 96) and fecal samples (n = 88) and tested in an independent group of fecal samples (n = 294), the methylated DNA marker ITGA4 and bacterial markers Fusobacterium nucleatum (Fn) and Pepetostreptococcusanaerobius (Pa) were identified from the candidate biomarkers for CRC and AA detection. A prediction score (pd-score) was constructed using the selected markers and fecal immunochemical test (FIT) for distinguishing AA and CRC from healthy subjects by logistic regression method. The diagnostic performance of the pd-score was compared with FIT and validated in the external validation cohort (n = 117) and in a large CRC screening cohort.

RESULTS

The pd-score accurately identified AA and CRC from healthy subjects with an area under the curve (AUC) of 0.958, at a specificity of 91.37%; the pd-score showed sensitivities of 95.38% for CRC and 70.83% for AA, respectively. In the external validation cohort, the sensitivities of the pd-score for CRC and AA detection were 94.03% and 80.00%, respectively. When applied in screening, the pd-score identified 100% (11/11) of CRC and 70.83% (17/24) of AA in participants with both colonoscopy results and qualified fecal samples, showing an improvement by 41.19% compared to FIT.

CONCLUSIONS

The current study developed a noninvasive and well-validated approach for AA and CRC detection, which could be applied widely as a diagnostic and screening test.

Effect of fixed orthodontic appliances on self-assessment and diagnosis of halitosis in undergraduate dental students

Background:

The effects of fixed orthodontic therapy on the occurrence of halitosis are not yet fully understood. This study aimed to evaluate the effect of fixed orthodontic appliances on self-assessment and diagnosis of halitosis in undergraduate dental students.

Materials and Methods:

Sixty-two undergraduate dental students were included in this cross-sectional study. Two groups (n = 31 per group) were composed of participants with (study group) or without (control group) fixed orthodontic appliance. Halitosis self-assessment and clinical diagnosis were assessed using a visual analogic scale (VAS) and sulfur volatile compounds (SVCs) assessment, respectively. The subjective (VAS) and objective (SVC) malodor assessments were classified in absence, light, moderate, or severe malodor. Chi-square Pearson test and Spearman's correlation were applied for data analysis, with a significance level of 5%.

Results:

The use of fixed orthodontic appliances had no effect on self-assessment (P = 0.490) or clinical diagnosis (P = 0.610) of halitosis. Self-assessment was not significantly associated with the diagnosis of halitosis regardless the use of fixed orthodontic appliance (P ≥ 0.737). Male participants showed higher diagnosis of halitosis (P = 0.007). SVC measurements showed the absence of halitosis in 51.6% and 58.1% of participants with or without orthodontic appliances, respectively.

Conclusion:

The use of fixed orthodontic appliances affected the self-assessment of halitosis but no SVC measurements. It was not verified a correlation between subjective and objective methods to diagnose halitosis in dental students.

The role of fecal sulfur metabolome in inflammatory bowel diseases

Sulfur metabolism and sulfur-containing metabolites play an important role in the human digestive system, and sulfur compounds and pathways are associated with inflammatory bowel diseases (IBD). In fact, cysteine metabolism results in the production of taurine and sulfate, and gut microbes catabolize them into hydrogen sulfide, a signaling molecule with various biological functions. Besides metabolites originating from sulfur metabolism, several other sulfur-containing metabolites of different classes were detected in human feces, consisting of non-volatile and volatile compounds. Sulfated steroids and bile acids such as taurine-conjugated bile acids are the major classes along with sulfur amino acids and sulfur-containing peptides. Indeed, sulfur-containing metabolites were described in stool samples from healthy subjects, patients suffering from colorectal cancer or IBD. In metabolomics-driven studies, around 50 known sulfur-containing metabolites were linked to IBD. Taurine, taurocholic acid, taurochenodeoxycholic acid, methionine, methanethiol and hydrogen sulfide were regularly reported in IBD studies, and most of them were elevated in stool samples from IBD patients. We summarized from this review that there is strong interplay between perturbed gut microbiota in IBD, and the consistently higher abundance of sulfur-containing metabolites, which potentially represent substrates for sulfidogenic bacteria such as Bilophila or Escherichia and promote their growth. These bacteria might shift their metabolism towards the degradation of taurine and cysteine and therefore to a higher hydrogen sulfide production.

Role of the oral microbiome, metabolic pathways, and novel diagnostic tools in intra-oral halitosis: a comprehensive update

Halitosis or oral malodor is one of the most common reasons for the patients' visit to the dental clinic, ranking behind only dental caries and periodontitis. In the present times, where social and professional communications are becoming unavoidable, halitosis has become a concern of growing importance. Oral malodor mostly develops due to the putrefaction of substrates by the indigenous bacterial populations. Although culture-based studies have provided adequate information on halitosis, the high throughput omics technologies have amplified the resolution at which oral microbial community can be examined and has led to the detection of a broader range of taxa associated with intra-oral halitosis (IOH). These microorganisms are regulated by the interactions of their ecological processes. Thus to develop effective treatment strategies, it is important to understand the microbial basis of halitosis. In the current review, we provide an update on IOH in context to the role of the oral microbiome, metabolic pathways involved, and novel diagnostic tools, including breathomics. Understanding oral microbiota associated with halitosis from a broader ecological perspective can provide novel insights into one's oral and systemic health. Such information can pave the way for the emergence of diagnostic tools that can revolutionize the early detection of halitosis and various associated medical conditions.

Effect of adrenaline and noradrenaline on biofilm formation and virulence factors of Streptococcus mutans UA159

OBJECTIVES

To evaluate in vitro the effects of adrenaline and noradrenaline on the biofilm formation on orthodontic brackets, acid production and expression of virulence genes of Streptococcus mutans UA159 (S. mutans).

DESIGN

S. mutans UA159 biofilm was formed on orthodontic brackets under exposure to adrenaline (100 μM), noradrenaline (50 μM) or PBS solution (control group) in triptone-yeast extract with 1 % sucrose. After 24 h, biofilm formation was quantified through Colony Forming Units / mL (CFU/mL) and RNA was extracted to perform gene expression analysis through real-time reverse transcriptase-PCR (RT-qPCR). Evaluation of acid production was carried out on planktonic cultures for 6 h. One-way ANOVA followed by Tukey's test was carried to determine statistical difference. The level of significance was set at 5 %.

RESULTS

Catecholamines stimulated biofilm formation of S. mutans in orthodontic brackets (p < 0,05) but did not interfere with acid production (pH reduction) or the expression of the tested genes related to biofilm formation (gtfB, gtfC, gbpA, gbpB, gbpC, gbpD and brpA), aciduric (relA) and acidogenic properties (ldh).

CONCLUSIONS

The present study was the first to demonstrate that catecholamines can stimulate S. mutans UA159 biofilm formation. These findings can contribute to clarify the role of stress on bacterial metabolism and contribute to the understanding of a possible role on caries development, mainly in orthodontic patients.

Relations of Psychosocial Factors and Cortisol with Periodontal and Bacterial Parameters: A Prospective Clinical Study in 30 Patients with Periodontitis Before and After Non-Surgical Treatment

(1) Background: The progression of periodontitis, induced by polymicrobial dysbiosis, can be modified by systemic or environmental factors such as stress or anxiety affecting host response. The purpose of this study is to evaluate the potential associations between psychosocial factors scores or salivary cortisol levels with clinical periodontal parameters and bacterial environment in patients with periodontitis; (2) Methods: Subgingival microbiota was collected in two pathological and one healthy sites from thirty diseased patients (before/after scaling and root planing (SRP)) and from one healthy site from thirty control patients. Usual clinical periodontal parameters were recorded, and a saliva sample was harvested. Patients completed stress and anxiety self-assessment questionnaires. Cortisol concentrations were determined by ELISA and bacteria were identified by PCR; (3) Results: No correlation between salivary cortisol and the stress-anxiety self-declared was found (p > 0.05), but high concentrations of this molecule were associated positively and linearly with periodontal pocket depth (p = 0.04). It appeared that certain psychosocial stressors are associated with a modulation of the bacterial colonization of pockets of diseased group (before/after SRP), notably concerning Tannerella forsythia (p = 0.02), Porphyromonas gingivalis (p = 0.03), Fusobacterium nucleatum (p = 0.049) and Campylobacter rectus (p = 0.01). (4) Conclusion: This study reveals associations between bacteria colonization and psychosocial parameters in periodontitis that needs to be further investigated.

The Role of Oral Microbiota in Intra-Oral Halitosis

Halitosis is a common ailment concerning 15% to 60% of the human population. Halitosis can be divided into extra-oral halitosis (EOH) and intra-oral halitosis (IOH). The IOH is formed by volatile compounds, which are produced mainly by anaerobic bacteria. To these odorous substances belong volatile sulfur compounds (VSCs), aromatic compounds, amines, short-chain fatty or organic acids, alcohols, aliphatic compounds, aldehydes, and ketones. The most important VSCs are hydrogen sulfide, dimethyl sulfide, dimethyl disulfide, and methyl mercaptan. VSCs can be toxic for human cells even at low concentrations. The oral bacteria most related to halitosis are Actinomyces spp., Bacteroides spp., Dialister spp., Eubacterium spp., Fusobacterium spp., Leptotrichia spp., Peptostreptococcus spp., Porphyromonas spp., Prevotella spp., Selenomonas spp., Solobacterium spp., Tannerella forsythia, and Veillonella spp. Most bacteria that cause halitosis are responsible for periodontitis, but they can also affect the development of oral and digestive tract cancers. Malodorous agents responsible for carcinogenesis are hydrogen sulfide and acetaldehyde.

Microbiota and Malodor-Etiology and Management

Accumulating evidence indicates that microbiota plays a critical role in physiological processes in humans. However, it might also contribute to body malodor by producing numerous odorous molecules such as ammonia, volatile sulfur compounds or trimethylamine. Although malodor is commonly overlooked by physicians, it constitutes a major problem for many otherwise healthy people. Thus, this review aims to investigate most common causes of malodor and describe potential therapeutic options. We searched PUBMED and Google Scholar databases to identify the clinical and pre-clinical studies on bad body smell, malodor, halitosis and microbiota. Unpleasant smell might originate from the mouth, skin, urine or reproductive fluids and is usually caused by odorants that are produced by resident bacterial flora. The accumulation of odorous compounds might result from diet, specific composition of microbiota, as well as compromised function of the liver, intestines and kidneys. Evidence-based guidelines for management of body malodor are lacking and no universal treatment exists. However, the alleviation of the symptoms may be achieved by controlling the diet and physical elimination of bacteria and/or accumulated odorants.

Gas Sensor Array System Properties for Detecting Bacterial Biofilms

Background:

Gas sensor array system is a device that mimics the work of how the nose smells using the gas sensors that could give response toward specific odors. It is used for characterizing the different blended gas that is suited with the biological working nose principle. Thus, it could be used to detect the dental and oral diseases. Periodontitis is one of the diseases caused by the damage on the teeth due to the chronic infection on the gingival structure marked with bacterial plaque and calculus. This study aims to develop an electric nose for odor detection application on the periodontal bacterial biofilm as early detection device for dental and oral disease.

Methods:

This device is designed as a portable device to ease the data acquisition. The measured data were stored at a database system connected to a real-time computer. A gas array sensor system with six gas sensors (TGS 826, TGS 2602, TGS 2600, TGS 2611, TGS 2612, and TGS 2620) has been assembled for the early detection application for dental and oral disease excreted by the bacterial biofilm that caused dental and oral disease, including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Streptococcus mutans, and Enterococcus faecalis.

Results:

TGS 826 and TGS 2602 sensor had the best response showed by the high ADC delta value.

Conclusion:

GS 826 and TGS 2602 sensor could be used as a candidate for early detection device for dental and oral disease.

Biological underpinnings from psychosocial stress towards appetite and obesity during youth: research implications towards metagenomics, epigenomics and metabolomics

Psychosocial stress, uncontrolled eating and obesity are three interrelated epidemiological phenomena already present during youth. This broad narrative conceptual review summarises main biological underpinnings of the stress-diet-obesity pathway and how new techniques can further knowledge. Cortisol seems the main biological factor from stress towards central adiposity; and diet, physical activity and sleep are the main behavioural pathways. Within stress-diet, the concepts of comfort food and emotional eating are highlighted, as cortisol affects reward pathways and appetite brain centres with a role for insulin, leptin, neuropeptide Y (NPY), endocannabinoids, orexin and gastrointestinal hormones. More recently researched biological underpinnings are microbiota, epigenetic modifications and metabolites. First, the gut microbiota reaches the stress-regulating and appetite-regulating brain centres via the gut-brain axis. Second, epigenetic analyses are recommended as diet, obesity, stress and gut microbiota can change gene expression which then affects appetite, energy homeostasis and stress reactivity. Finally, metabolomics would be a good technique to disentangle stress-diet-obesity interactions as multiple biological pathways are involved. Saliva might be an ideal biological matrix as it allows metagenomic (oral microbiota), epigenomic and metabolomic analyses. In conclusion, stress and diet/obesity research should be combined in interdisciplinary collaborations with implementation of several -omics analyses.

Induction and inhibition of oral malodor

Volatile sulfur compounds (VSCs) such as hydrogen sulfide (H₂ S) and methyl mercaptan (CH₃ SH) are the main components of oral malodor, and are produced as the end products of the proteolytic processes of oral microorganisms. The main pathway of proteolysis is the metabolism of sulfur-containing amino acids by gram-negative anaerobic bacteria. Gram-positive bacteria may promote VSC production by gram-negative anaerobes by cleaving sugar chains from glycoproteins and thus providing proteins. A large variety of bacteria within the oral microbiota are thought to be involved in the complex phenomenon of halitosis. Oral microbiota associated with a lack of oral malodor, oral microbiota associated with severe and H₂ S-dominant oral malodor, and oral microbiota associated with severe and CH₃ SH-dominant oral malodor have been distinguished through molecular approaches using the 16S rRNA gene. Pathological halitosis may primarily be addressed through treatment of causative diseases. In all cases, plaque control is the basis of oral malodor control, and dentifrices, mouthwashes, and functional foods play a supplementary role in addition to brushing. Recently, the use of natural ingredients in products tends to be favored due to the increase in antibiotic-resistant strains and the side effects of some chemical ingredients. In addition, probiotics and vaccines are expected to offer new strategies for improving the oral conditions through mechanisms other than antibacterial agents.

Systematic Review of Gut Microbiota and Major Depression

Background: Recently discovered relationships between the gastrointestinal microbiome and the brain have implications for psychiatric disorders, including major depressive disorder (MDD). Bacterial transplantation from MDD patients to rodents produces depression-like behaviors. In humans, case-control studies have examined the gut microbiome in healthy and affected individuals. We systematically reviewed existing studies comparing gut microbial composition in MDD and healthy volunteers. Methods: A PubMed literature search combined the terms "depression," "depressive disorder," "stool," "fecal," "gut," and "microbiome" to identify human case-control studies that investigated relationships between MDD and microbiota quantified from stool. We evaluated the resulting studies, focusing on bacterial taxa that were different between MDD and healthy controls. Results: Six eligible studies were found in which 50 taxa exhibited differences (p < 0.05) between patients with MDD and controls. Patient characteristics and methodologies varied widely between studies. Five phyla-Bacteroidetes, Firmicutes, Actinobacteria, Fusobacteria, and Protobacteria-were represented; however, divergent results occurred across studies for all phyla. The largest number of differentiating taxa were within phylum Firmicutes, in which nine families and 12 genera differentiated the diagnostic groups. The majority of these families and genera were found to be statistically different between the two groups in two identified studies. Family Lachnospiraceae differentiated the diagnostic groups in four studies (with an even split in directionality). Across all five phyla, nine genera were higher in MDD (Anaerostipes, Blautia, Clostridium, Klebsiella, Lachnospiraceae incertae sedis, Parabacteroides, Parasutterella, Phascolarctobacterium, and Streptococcus), six were lower (Bifidobacterium, Dialister, Escherichia/Shigella, Faecalibacterium, and Ruminococcus), and six were divergent (Alistipes, Bacteroides, Megamonas, Oscillibacter, Prevotella, and Roseburia). We highlight mechanisms and products of bacterial metabolism as they may relate to the etiology of depression. Conclusions: No consensus has emerged from existing human studies of depression and gut microbiome concerning which bacterial taxa are most relevant to depression. This may in part be due to differences in study design. Given that bacterial functions are conserved across taxonomic groups, we propose that studying microbial functioning may be more productive than a purely taxonomic approach to understanding the gut microbiome in depression.

Stress-related salivary proteins affect the production of volatile sulfur compounds by oral bacteria

OBJECTIVE

To determine whether stress-related substances and sex hormones influence the growth and in vitro production of volatile sulfur compounds (VSCs) by Solobacterium moorei and Fusobacterium nucleatum.

MATERIALS AND METHODS

Bacteria growth and VSCs production were evaluated in the presence of alpha-amylase, beta-defensin-2, mucin, estradiol, and progesterone. Growth was evaluated by colony counting, and the production of the VSCs hydrogen sulfide (H₂ S) and methyl mercaptan (CH₃ SH) was measured using the Oral Chroma™ instrument.

RESULTS

Mucin induced the production of H₂ S by both bacteria, but had a slight inhibitory effect on CH₃ SH production by F. nucleatum. It also increased the viability of F. nucleatum. Alpha-amylase increased H₂ S production by S. moorei and CH₃ SH production by F. nucleatum, but had no effect on H₂ S production by F. nucleatum. No substance altered the viability of S. moorei. No effects of beta-defensin-2, estradiol, or progesterone were observed.

CONCLUSION

The salivary stress-related proteins mucin and alpha-amylase altered VSCs production by F. nucleatum and S. moorei, favoring H₂ S production. These findings are a step toward understanding the relation between stress and increased amounts of H₂ S.

A Current Approach to Halitosis and Oral Malodor- A Mini Review

BACKGROUND

Halitosis, in other words, oral malodor is an important multifactorial health problem affecting the psychological and social life of individuals and is the most common reason for referral to dentists after dental caries and periodontal diseases.

OBJECTIVE

The objective of this review was to present and discuss conventional and recently introduced information about the types, causes, detection and treatment methods of halitosis.

METHODS

An expanded literature review was conducted which targeted all articles published in peer-reviewed journals relating to the topic of halitosis. Only articles written in Turkish and English languages were considered. The review itself began with a search of relevant subject headings such as 'halitosis, oral malodor, volatile sulfur compounds in PubMed/Medline, Scopus, Google Scholar and Tubitak Ulakbim databases. A hand search of references was also performed.

RESULTS

When search results are combined, the total number of relevant literature was found to be 4646 abstracts and 978 full-text articles. Abstracts, editorial letters were not included and about half of full-text articles were not related to dental practice. Among the remaining 124 full-text articles, duplicated articles and articles written other than Turkish and English languages were removed and 54 full-text articles were used for this review.

DISCUSSION

According to the reviewed articles, both conventional and new methods were introduced in the management of halitosis. However, conventional methods seem to be more effective and widely used in the diagnosis and treatment of halitosis.

CONCLUSION

As being first line professionals, dentists must analyze and treat oral problems which may be responsible for the patient's malodor, and should inform the patient about halitosis causes and oral hygiene procedures (tooth flossing, tongue cleaning, appropriate mouthwash and toothpaste selection and use) and if the problem persists, they should consult to a medical specialist.

The salivary microbiome is consistent between subjects and resistant to impacts of short-term hospitalization

In recent years, a growing amount of research has begun to focus on the oral microbiome due to its links with health and systemic disease. The oral microbiome has numerous advantages that make it particularly useful for clinical studies, including non-invasive collection, temporal stability, and lower complexity relative to other niches, such as the gut. Despite recent discoveries made in this area, it is unknown how the oral microbiome responds to short-term hospitalization. Previous studies have demonstrated that the gut microbiome is extremely sensitive to short-term hospitalization and that these changes are associated with significant morbidity and mortality. Here, we present a comprehensive pipeline for reliable bedside collection, sequencing, and analysis of the human salivary microbiome. We also develop a novel oral-specific mock community for pipeline validation. Using our methodology, we analyzed the salivary microbiomes of patients before and during hospitalization or azithromycin treatment to profile impacts on this community. Our findings indicate that azithromycin alters the diversity and taxonomic composition of the salivary microbiome; however, we also found that short-term hospitalization does not impact the richness or structure of this community, suggesting that the oral cavity may be less susceptible to dysbiosis during short-term hospitalization.

Sensitivity of salivary hydrogen sulfide to psychological stress and its association with exhaled nitric oxide and affect

BACKGROUND

Hydrogen sulfide (H₂S) is the third gasotransmitter recently discovered after nitric oxide (NO) and carbon monoxide. Both NO and H₂S are involved in multiple physiological functions. Whereas NO has been shown to vary with psychological stress, the influence of stress on H₂S and the relationship between H₂S and NO are unknown. We therefore examined levels of salivary H₂S and NO in response to a stressful final academic exam period.

METHODS

Measurements of stress, negative affect, and fraction of exhaled NO (FE_NO), were obtained from students (N=16) and saliva was collected at three time points: low-stress period in the semester, early exam period, and late exam period. Saliva was immediately analyzed for H₂S with the fluorescent probe Sulfidefluor-4.

RESULTS

H₂S increased significantly during the early exam period and FE_NO decreased gradually towards the late exam period. H₂S, FE_NO, negative affect, and stress ratings were positively associated with each other: as stress level and negative affect increased, values of H₂S increased; in addition, as FE_NO levels decreased, H₂S also decreased. Asthma status did not modify these associations.

CONCLUSION

Sustained academic stress increases H₂S and these changes are correlated with NO and the experience of stress and negative affect. These findings motivate research with larger samples to further explore the interaction and function of H₂S and FE_NO during psychological stress.