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.

Co-Infection Rates between SARS-CoV-2 and RSV in Oropharyngeal, Nasopharyngeal Aspirate and Saliva Samples of COVID-19 Patients, Shiraz, South of Iran

Statement of the Problem

Determining the prevalence of respiratory viruses' coinfection with coronavirus disease 2019 (COVID-19) is essential to defining its true clinical influence.

Purpose

This study aimed to evaluate co-infection rates between severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) and respiratory syncytial virus (RSV) in infected patients in Shiraz, south of Iran.

Materials and Method

In a cross-sectional descriptive study, oropharyngeal, nasopharyngeal aspirate (NPA), and saliva samples of 50 COVID-19 patients who were referred to Ali-Asghar hospital (Shiraz, Iran) from March to August 2020, were collected. A control group consisted of age and sex-matched healthy participants. The nasopharyngeal and oropharyngeal aspirates were collected by sterile swabs. All cases were hospitalized, and all SARS-CoV-2 patients had a fever and respiratory symptoms. The samples were packed in a vial with 1 mL of transport medium and transported to the Valfagre specialty laboratory, where they were tested for RSV using a real-time polymerase chain reaction (PCR).

Results

100 nasopharyngeal/oropharyngeal aspirates and saliva samples including 50 healthy controls (24 females, 26 males) and 50 COVID-19 patients' samples (27 males and 23 females) were studied. There was no significant difference regarding age as well as gender between both groups (p> 0.05). None of the healthy subjects was infected with RSV; however, 5(10%) patients from COVID-19 group were infected with the RSV virus. Chi-square test did not show a significant difference between RSV infection in COVID-19 patients and healthy subjects.

Conclusion

The outcome of present research showed that concurrent RSV with COVID 19 infection might be seen in hospitalized patients in Shiraz Southwest of Iran. For more reliable findings, further research on bigger populations, including more pathogens in several places around the country, and considering the severity of symptoms is required.

Effect of Pilocarpine Mouthwash on Salivary Flow Rate in Patients with Xerostomia: A Systematic Review and Meta-Analysis

Statement of the Problem

Xerostomia is a subjective sensation of dry mouth considered as a complex state affecting multiple oral functions. Pilocarpine may be a useful medication for the treatment of xerostomia, but its side effects limit its use under certain conditions. Recent studies have focused on the pilocarpine mouthwash as an alternative.

Purpose

We have undertaken this study to review the latest available scientific evidence systematically, concerning the effects of pilocarpine mouthwash on salivary flow rate in patients with xerostomia.

Materials and Method

An electronic search for randomized controlled trials published in English until September 2021 related to pilocarpine mouthwash and salivary flow rate in patients with dry mouth was performed in PubMed/Medline, Web of Science, Google Scholar, Embase, and Scopus. A random-effects meta-analysis was conducted to evaluate the relationship between the groups.

Results

Two papers with 86 patients were selected for the final review based on strict eligibility criteria. According to the results of the meta-analysis, the mean visual analogue scale in the patient treated with pilocarpine mouthwash was 0.88 unit lower than that of the control group in the fourth week follow; however, it was not statistically significant (pooled mean difference=-0.88, 95% CI = (-2.72; 0.95), p= 0.34).

Conclusion

It seems that the use of pilocarpine mouthwash can increase the salivary flow rates; however, no optimal dose and application regimen can currently be suggested due to the high heterogeneity of the data. Regarding the relief of the symptoms using pilocarpine mouthwash, the existing evidence does not support its effectiveness.

Salivary Oxidative Stress, Total Protein, Iron and pH in Children with β-Thalassemia Major and their Correlation with Dental Caries

Statement of the Problem

Iron overload in β-thalassemia major leads to oxidative damage to tissues, which may have an important role in the onset and progression of oral diseases.

Purpose

The aim of this study was to evaluate the salivary oxidative stress indicators, total protein, iron, and pH in children with β-thalassemia major and their relationship with the status of dental caries in comparison with healthy children.

Materials and Method

In this case-control study, 68 β-thalassemia major and healthy children, who were age- and sex matched, were selected. Two mililiters of saliva was collected from each child. The pH was measured using pH meter paper. Thiobarbituric acid reactive substances (TBARS) as salivary lipid peroxidation index, total antioxidant capacity (TAC), total protein, and iron were measured by spectrophotometry. Data were analyzed by SPSS ver. 22 software with Pearson and independent samples t-test.

Results

TBARS, TAC, iron and dmft index in the β-thalassemia major group were significantly higher and pH was significantly lower than the control group (p< 0.001). The total protein difference between the two groups was not significant (p= 0.081).

Conclusion

Considering the higher salivary TBARS in the β-thalassemia major group, oxidative stress can be considered as a risk factor for dental caries in children with β-thalassemia major. Prescription of antioxidant supplements especially natural antioxidants in the diet of children with β-thalassemia major is recommended to reduce oxidative stress.

Effects of Methamphetamine Withdrawal on the Volume and pH of Stimulated Saliva

STATEMENT OF THE PROBLEM

As a stimulant drug of the central nervous system, methamphetamine reduces salivary secretion by stimulating inhibitory α2-receptors in the sympathetic system. The acidity of this substance reduces the salivary pH and causes severe dental caries and erosion in the cervical region of teeth, appearing as "meth mouth".

PURPOSE

This study aimed to determine the effects of methamphetamine withdrawal on the volume and pH of stimulated saliva in patients under treatment at rehabilitation centers.

MATERIALS AND METHOD

This descriptive cross-sectional study was conducted on a total of 20 individuals at the rehabilitation centers of Gorgan, Iran. The volume and pH of stimulated saliva were measured at three intervals: before withdrawal, four days after withdrawal, and 30 days after withdrawal. Data analysis was performed using ANOVA test in SPSS.

RESULTS

The results showed a significant difference in the mean volume of saliva before and after withdrawal (p< 0.05). Thirty days after withdrawal, the mean volume of saliva was significantly different from the mean volume after four days (p< 0.05). Moreover, the mean pH of saliva after withdrawal was significantly different from the mean pH before withdrawal (p< 0.001). On the other hand, the mean salivary pH at 30 days after withdrawal was not significantly different from the mean pH on the fourth day after withdrawal (p> 0.05).

CONCLUSION

It seems that methamphetamine withdrawal influences the volume and pH of stimulated saliva in patients under treatment at rehabilitation centers.

Evaluation of Salivary Level of Heat Shock Protein 70 in Patients with Chronic Periodontitis

STATEMENT OF THE PROBLEM

Traditional clinical criteria are usually not sufficient for determining the sites of active periodontal disease, monitoring the response to treatment, or measuring the susceptibility to future disease development. Past studies have shown that heat shock protein 70 (HSP70) are involved in the etiology of periodontal disease.

PURPOSE

The aim of this study was to evaluate the level of HSP70 in saliva of patients with chronic periodontitis (CP).

MATERIALS AND METHOD

In our case-control study, the saliva samples of 45 patients with CP and 45 age- and sex-matched healthy subjects were collected. Salivary HSP70 was measured by enzyme-linked immunosorbent assay method. The results were analyzed by statistical tests using SPSS 16 and the statistically significant difference was set at p< 0.05.

RESULTS

In this study, the mean salivary HSP70 level was 2.81±0.61ng/ml in the patient group and 1.96±0.77ng/ml in the healthy group, with a significant difference (p< 0.05). In addition, the results of spearman correlation analysis showed a positive correlation between salivary HSP 70 and clinical periodontal index.

CONCLUSION

The results of this study showed that the salivary HSP70 level in patients with CP is higher than that in healthy subjects. As a result, salivary HSP70 might be considered as a marker in the pathogenesis of CP.

Evaluation of the Relationship between Salivary Lipids, Proteins and Total Antioxidant Capacity with Gingival Health Status in Type-1 Diabetic Children

STATEMENT OF THE PROBLEM

Alteration in salivary composition and its effect on the oral cavity in diabetic child patients remains equivocal.

PURPOSE

This study was performed to assess the relationship between salivary factors and gingival status in children with type-1 diabetes mellitus (DM).

MATERIAL AND METHOD

In this cross-sectional study, 120 subjects aged 6-16 years (60 well-controlled and poorly-controlled diabetics and 60 healthy individuals) were examined to determine the gingival index (GI) and plaque index (PI). The unstimulated saliva samples were collected to measure the salivary triglyceride, cholesterol, albumin, α-amylase, total protein levels by the laboratory kits. Total antioxidant capacity and the free radicals scavenger index were measured by the Ferric Reducing Ability Of Plasma (FRAP) and 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) assays, respectively. Data were analyzed by parametric and non-parametric, Pearson correlation, and t tests at a 5% error level.

RESULTS

GI of diabetics was significantly higher than that of healthy individuals (1.51± 0.71 and 0.9±0.81, respectively, p< 0.001). No significant difference was found between the PI of diabetics compared to healthy volunteers (1.59±0.69, 1.63±0.74, respectively). The levels of salivary triglyceride and cholesterol, albumin and total proteins in healthy subjects were significantly higher than that in people with DM (p< 0.001). A significantly more salivary α-amylase activity was found in diabetics compared to non-diabetics (p< 0.001). No significant differences were found between diabetic and non-diabetic subjects in terms of DPPH (95.5, 95.9%, respectively) and FRAP (9.77±0.13, 9.78±0.12 (µmol/mL), respectively).

CONCLUSION

More gingival inflammation and salivary α-amylase activity and lower level of salivary lipids, albumin, and total proteins were found in diabetic patients, but there was no association between the level of lipids, proteins, and the total antioxidant capacity of saliva with periodontal health indicators in patients with DM and healthy individuals.

Does Hypertension affect Saliva Properties?

Statement of the Problem:

Systemic conditions can affect the salivary glands and oral health. Hypertension induces xerostomia. Because the function of saliva is related to its quality and quantity, therefore, any changes in saliva can lead to diminished quality of patient’s life.

Purpose:

The aim of this study was to determine the relationship between pH and viscosity of cumulative unstimulated saliva and hypertension in adults with sustained hypertension.

Materials and Method:

This cross sectional study took place on patients referred to oral medicine faculty of Shahid Sadoughi University of Medical Science. The patients’ blood pressure was measured and the 135 patients fitting the inclusion criteria participated in the study. Their unstimulated cumulative saliva was collected by spitting method and pH of the samples was measured by digital pH-meter set. The viscosity of the samples was measured by comparing the amount of saliva displacement in the thistle tube with control fluids at mm/10 seconds. The data was analyzed by SPSS version 20 software and ANOVA tests and Tukey multiple comparison and their nonparametric equivalent (p≤ 0.005).

Results:

The results of this study showed that there was a significant relationship between pH and viscosity of unstimulated saliva of normotensive and borderline hypertensive patients (p<.0001and p< .005, respectively) and between normotensive and stage I hypertensive patients (p<.0001, p<0.000). Therefore, hypertension had a direct and significant relationship with saliva viscosity but a reverse relationship with saliva pH.

Conclusion:

Hypertension can reduce the pH and increase the salivary viscosity in hypertensive patients, which subsequently lead to changes in quality and quantity of secreted saliva and influence the oral health and quality of the patient’s life.

Isolation and Identification of Non- Commensal Pathogenic Bacteria in the Saliva of Patients Candidate for Liver Transplant: A Cross Sectional Study in Shiraz, South of Iran

STATEMENT OF THE PROBLEM

Liver cirrhosis is the end stage of liver failure. It is mentioned as one of the main etiologies of morbidity and mortality in the world. The human salivary bacteria may induce oral disorders and interact with other body microbiota.

PURPOSE

The aim of the present study is to identify the pathogenic bacteria of non-oral origin from the saliva samples of patients with end stage liver failure.

MATERIALS AND METHOD

In this cross-sectional study, the saliva samples of 88 end stage liver disease cases and 84 age- and sex-matched healthy subjects were collected. The samples were cultured using gram staining and API20E Kit.

RESULTS

According to the statistical analysis, the total amount of the non-commensal bacteria was significantly higher in chronic liver failure (CLF) group than controls (p= 0.001). There was no significant difference between both groups for the presence of other bacteria (p= 0.001) except for Escherichia coli (E. coli). E. coli was isolated from the saliva of 15 cases and only 2 controls.

CONCLUSION

Oral cavity may act as a reservoir for enteric bacteria such as E. coli in liver failure patients. Adequate oral and general hygiene might reduce the risk of systemic infection especially in immunocompromised cases.

Comparing Serum and Salivary Levels of Vitamin D in Patients with Recurrent Aphthous Stomatitis and Healthy Individuals

STATEMENT OF THE PROBLEM

Recurrent aphthous stomatitis (RAS) is the most prevalent ulcerative condition of the oral mucosa. Many studies have emphasized on immunologic factors as the reason of inducing RAS; however, the exact etiologic cause of RAS has not been identified yet. Vitamin D has an endocrine function and regulatory effects on the immune system. It has potential therapeutic effects on autoimmune diseases, psoriasis, and neoplasms. Vitamin D deficiency has been detected in some autoimmune diseases such as rheumatoid arteritis.

PURPOSE

The aim of the present study was to compare the serum and salivary levels of vitamin D in patients with RAS and healthy individuals.

MATERIALS AND METHOD

In this cross sectional study, patients with RAS, referring to the Department of Oral Medicine, Tabriz Faculty of Dentistry, were evaluated after taking medical history, clinical examinations, and completing an informed consent form. The serum and salivary vitamin D levels were compared between case (n=26) and control (n=26) groups.

RESULTS

The mean serum vitamin D levels in the case and control groups were 33.0.7±12.41 and 50.89±9.30 (ng/dL), respectively, with a statistically significant difference (p<0.001). On the other hand, the mean salivary vitamin D levels in the case and control groups were 17.36± 8.01 and 20.79±6.31 (ng/dL), respectively, with no statistically significant difference (p= 0.09). In addition, the correlation between the serum and salivary levels of vitamin D was 56%, being statistically significant (p< 0.001).

CONCLUSION

The serum levels of vitamin D in patients with RAS were significantly less than that in healthy individuals; however, there were no significant differences in salivary vitamin D levels between patients with RAS and healthy individuals. In addition, there was a significant and positive correlation between serum and salivary levels of vitamin D in all patients.