There is a very complicated electrolytical environment in oral cavity with plenty of microorganisms existing there. Various forms of corrosion would develop when metallic prosthesis functions in mouth. One important corrosive form is microbial corrosion. The metabolic products, including organic acid and inorganic acid, will affect the pH of the surface or interface of metallic prosthesis and make a change in composition of the medium, thus influencing the electron-chemical reaction and promoting the development of corrosion. The problem of develpoment of microbial corrosion on dental alloy in the oral environment lies in the primary condition that the bacteria adhere to the surface of alloy and form a relatively independent environment that promotes corrosion.
Corrosion ; Dental Alloys ; chemistry ; Humans ; Mouth ; microbiology ; Saliva ; microbiology ; Surface Properties

Objective: To explore the correlation between age and diversity and microbial composition in saliva and feces microbiota in high-risk population of upper gastrointestinal cancer. Methods: Based on the national project on early diagnosis and early treatment of upper gastrointestinal cancer, 38 participants were enrolled in Linzhou in Henan province in August 2019. The participant information was collected by questionnaire. Saliva and feces specimens were collected from each participant for 16S rRNA sequencing and bioinformatics analysis. Spearman rank correlation was used to analyze the correlation between age and α diversity (Observed ASVs and Shannon index) and relative abundance of microbiota (phyla, genera, and species) in saliva and feces. Results: The median age (age range) of 38 participants was 54 (43-60) years old, and there were 16 males (42.1%). The Observed ASVs of saliva was negatively correlated with age (r_s=-0.35, P<0.05), but the observed ASVs of feces was not correlated with age. In saliva, the relative abundance of Treponema (r_s=‒0.44, P<0.05), Alloprevotella (r_s=‒0.42, P<0.05), and Porphyromonas (r_s=‒0.41,P<0.05) were significantly negatively correlated with age. At the species level, the relative abundance of Porphyromonas endodontalis, Alloprevotella tannerae, Haemophilus influenza, Moraxella bovoculi, Prevotella sp.oral clone ID019, and Prevotella sp.oral clone ASCG10 in saliva were significantly negatively correlated with age, and the r_s values were -0.50, -0.40, -0.38, -0.35, -0.33 and -0.33 (P<0.05), respectively. In feces, the relative abundance of Enterobacteria (r_s=-0.35, P<0.05), Escherichia (r_s=-0.33, P<0.05), and Bifidobacteria (r_s=0.33, P<0.05) were correlated with age. At the species level, the relative abundance of Romboutsia sedimentorum, Citrobacter murliniae, and bacteroides uniformis in feces were correlated with age, and the r_s values were -0.42, -0.37 and 0.36 (P<0.05), respectively. Conclusion: Age of the high-risk population of upper gastrointestinal cancer is correlated with the relative abundance of microbiota in saliva and feces.
Male ; Humans ; Adult ; Saliva/microbiology* ; RNA, Ribosomal, 16S/genetics* ; Feces/microbiology* ; Microbiota ; Gastrointestinal Neoplasms

OBJECTIVE: To investigate the characterization of the salivary microbiome in people with obesity and the differences in microbial composition, gene function and metabolic pathways of salivary microbiome between people with obesity and normal weight controls. METHODS: The study was carried out in people with obesity and age- and sex-matched normal weight controls. None of these selected participants had the systemic disease, oral mucosal disease or periodontal disease. Unstimulated saliva samples were collected and oral examination was conducted. DNAs from saliva samples were extracted and sequenced in an Illumina NextSeq 500 platform. Community composition, linear discriminant analysis of taxonomic differences,gene prediction, gene set construction and annotation of gene function were performed. RESULTS: The classified bacterial reads of the samples were 2 630 428 for each sample. A total of 11 phyla, 19 classes, 26 orders, 41 families, 62 genera and 164 species were detected ultimately. All samples had the same predominant phyla (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria and Fusobacteria). There were statistical differences between the groups at the class, order, family, genus and species levels. At the class level, Negativicutes and Erysipelotrichia were more abundant in the obesity group, while Flavobacteriia and Bateroidetes dominated in normal weight group (P<0.05). At the species level, 16 showed significant differences in relative abundance among the groups, in which Prevotella melaninogenica,Prevotella salivae,Solobacterium moorei and Atopobium parvulum ware more abundant in the obesity group, whereas Streptococcus sanguinis dominated in normal weight group (P<0.05). The people with obesity had a higher number of salivary microbial genes (P<0.05). We produced statistics on gene prediction and found salivary microbiome of obesity group had a higher number of genes (P < 0.05). Genes associated with the pathways of metabolism and environmental information processing and human diseases were significantly enriched in the saliva samples of people with obesity (P < 0.01). CONCLUSION Significant differences were seen in composition, gene function and metabolic pathways of salivary microbiome between people with obesity and normal weight people. We hope to go on further study with larger sample size in the near future.
Bacteria/isolation & purification* ; Female ; Humans ; Male ; Microbiota ; Obesity/microbiology* ; Pilot Projects ; RNA, Ribosomal, 16S ; Saliva/microbiology*

BACKGROUND: About half of the world population is infected with H. pylori, but the transmission and the source of this infection are still unclear. Recently, dental plaque (DP) and saliva have been implicated as possible sources of H. pylori infection. This study was done to investigate the detection rates of H. pylori in the DP and saliva by use of PCR depending on H. pylori infection state of gastric mucosa. METHODS: In 46 subjects, gastric H. pylori colonization was evaluated with CLO test, microscopy of Gram stained mucosal smear, culture and histology after modified Giemsa staining in the antrum and body, respectively. A patient was regarded as H. pylori positive if one or more of the four aforementioned test methods demonstrated H. pylori colonization of the gastric mucosa. For detection of H. pylori in the DP and saliva, PCR assay was done with ET4-U and ET4-L primers. To estimate the sensitivity and specificity of this PCR, H. pylori positivity was evaluated in the antrum and body, separately. RESULTS: The sensitivity of mucosal PCR was 50.0% (27/54) and the specificity 86.8% (33/38). When a subject was regarded as H. pyloi positive, if either antrum or body mucosal H. pylori was is positive, the positive rate of mucosal PCR was 62.1% (18 subjects) in the 29 H. pylori-positive and 17.6% (3 subjects) in the 17 H. pylori-negative subjects. DP PCR was positive in 2 of 29 H. pylori-positive subjects (6.9%) and none in the 17 H. pylori-negative (0%). Saliva PCR was positive in 4 of 14 H. pylori-positive subjects (28.6%) and none of 6 H. pylori-negative (0%). CONCLUSION: The detection rates of H. pylori in DP and saliva by PCR were rather low, 6.9% and 28.6%, respectively, and these rates might have been underestimated by low sensitivity of the PCR method used in this study. However, the results that H. pylori was found in the DP and saliva suggest that the oral cavity can perform a role as a reservoir of H. pylori in Korea.
Dental Plaque/microbiology* ; Gastric Mucosa/microbiology ; Helicobacter pylori/isolation & purification* ; Human ; Polymerase Chain Reaction ; Saliva/microbiology* ; Sensitivity and Specificity

The reduction of nitrate to nitrite by the oral microbiota has been proposed to be important for oral health and results in nitric oxide formation that can improve cardiometabolic conditions. Studies of bacterial composition in subgingival plaque suggest that nitrate-reducing bacteria are associated with periodontal health, but the impact of periodontitis on nitrate-reducing capacity (NRC) and, therefore, nitric oxide availability has not been evaluated. The current study aimed to evaluate how periodontitis affects the NRC of the oral microbiota. First, 16S rRNA sequencing data from five different countries were analyzed, revealing that nitrate-reducing bacteria were significantly lower in subgingival plaque of periodontitis patients compared with healthy individuals (P < 0.05 in all five datasets with n = 20-82 samples per dataset). Secondly, subgingival plaque, saliva, and plasma samples were obtained from 42 periodontitis patients before and after periodontal treatment. The oral NRC was determined in vitro by incubating saliva with 8 mmol/L nitrate (a concentration found in saliva after nitrate-rich vegetable intake) and compared with the NRC of 15 healthy individuals. Salivary NRC was found to be diminished in periodontal patients before treatment (P < 0.05) but recovered to healthy levels 90 days post-treatment. Additionally, the subgingival levels of nitrate-reducing bacteria increased after treatment and correlated negatively with periodontitis-associated bacteria (P < 0.01). No significant effect of periodontal treatment on the baseline saliva and plasma nitrate and nitrite levels was found, indicating that differences in the NRC may only be revealed after nitrate intake. Our results suggest that an impaired NRC in periodontitis could limit dietary nitrate-derived nitric oxide levels, and the effect on systemic health should be explored in future studies.
Humans ; Nitrates ; Nitric Oxide ; Nitrites ; RNA, Ribosomal, 16S/genetics* ; Periodontitis/microbiology* ; Bacteria ; Dental Plaque/microbiology* ; Saliva/microbiology* ; Microbiota/genetics*

The aim of this study was to evaluate the presence of Helicobacter (H.) spp. in swine affected by gastric ulceration. Stomachs from 400 regularly slaughtered swine were subjected to gross pathological examination to evaluate the presence of gastric ulcers. Sixty-five samples collected from ulcerated pars esophagea and 15 samples from non-ulcerated pyloric portions were submitted to histopathological and molecular analyses, to detect Helicobacter spp., H. suis and H. pylori by PCR. Feces and saliva swabs were also collected from 25 animals in order to detect in vivo the presence of Helicobacter spp.. Gastric ulcers were detected in 373 cases (93%). The presence of ulcers in association with inflammatory processes was further confirmed by histological examination. Forty-nine percent (32/65) of the ulcerated esophageal portions as well as 53% (8/15) of the non-ulcerated pyloric portions were positive for Helicobacter spp. by PCR. The Helicobacter spp. positive samples were also positive for H. suis, while H. pylori was not detected. These results were confirmed by restriction enzyme analysis. With regard to feces and saliva samples, 15/25 (60%) and 16/25 (64%) were positive for Helicobacter spp. PCR, respectively but all were negative in H. suis and H. pylori specific PCR.
Animals ; Feces/*microbiology ; Helicobacter/*isolation & purification ; Polymerase Chain Reaction/veterinary ; Restriction Mapping/veterinary ; Saliva/*microbiology ; Stomach/*microbiology ; Stomach Ulcer/microbiology/pathology/*veterinary ; Swine ; Swine Diseases/*microbiology/pathology

OBJECTIVETo investigate the prevalence of Actinobacillus actinomycetemcomitans (Aa) in whole saliva of different types of periodontitis and compare the detections of Aa between saliva and pooled subgingival plaque sample, and analyze the relationship between Aa and clinical conditions.

METHODSUnstimulated whole saliva samples and pooled subgingival samples were collected from 50 aggressive periodontitis (AgP) patients, 48 chronic periodontitis (CP) patients and 25 subjects with no periodontitis, and Aa was detected in these samples by PCR method.

RESULTSThe prevalence of Aa in whole saliva of AgP patients was significantly higher than in subjects with no periodontitis (32% vs. 4%, P<0.01) and CP patients (32% vs. 15%, P<0.05). Aa was also more frequently detected in whole saliva sample than in pooled subgingival sample of AgP patients (32% vs. 16%, P<0.05). Subjects younger than 30 years old were more likely to present Aa in whole saliva ( OR = 3.23, P<0.05) and percentage of sites with bleeding index (BI) > or = 3 over 70% was a risk indicator for the presence of Aa in whole saliva

CONCLUSIONSThe detection of Aa in whole saliva sample of AgP patients was more frequent than in pooled subgingival plaque samples, and also more frequent than in CP patients and subjects with no periodontitis, which suggest that Aa may participate in the initiation and progression of aggressive periodontitis.

Adult ; Aggregatibacter actinomycetemcomitans ; isolation & purification ; Chronic Periodontitis ; microbiology ; Dental Plaque ; microbiology ; Female ; Humans ; Male ; Middle Aged ; Periodontitis ; microbiology ; Saliva ; microbiology ; Young Adult

The biodiversity of the mycobiome, an important component of the oral microbial community, and the roles of fungal-bacterial and fungal-immune system interactions in the pathogenesis of oral lichen planus (OLP) remain largely uncharacterized. In this study, we sequenced the salivary mycobiome and bacteriome associated with OLP. First, we described the dysbiosis of the microbiome in OLP patients, which exhibits lower levels of fungi and higher levels of bacteria. Significantly higher abundances of the fungi Candida and Aspergillus in patients with reticular OLP and of Alternaria and Sclerotiniaceae_unidentified in patients with erosive OLP were observed compared to the healthy controls. Aspergillus was identified as an "OLP-associated" fungus because of its detection at a higher frequency than in the healthy controls. Second, the co-occurrence patterns of the salivary mycobiome-bacteriome demonstrated negative associations between specific fungal and bacterial taxa identified in the healthy controls, which diminished in the reticular OLP group and even became positive in the erosive OLP group. Moreover, the oral cavities of OLP patients were colonized by dysbiotic oral flora with lower ecological network complexity and decreased fungal-Firmicutes and increased fungal-Bacteroidetes sub-networks. Third, several keystone fungal genera (Bovista, Erysiphe, Psathyrella, etc.) demonstrated significant correlations with clinical scores and IL-17 levels. Thus, we established that fungal dysbiosis is associated with the aggravation of OLP. Fungal dysbiosis could alter the salivary bacteriome or may reflect a direct effect of host immunity, which participates in OLP pathogenesis.
Adult ; Bacteria ; isolation & purification ; Case-Control Studies ; Dysbiosis ; complications ; microbiology ; Female ; Humans ; Lichen Planus, Oral ; complications ; microbiology ; Male ; Microbiota ; Middle Aged ; Mouth Mucosa ; microbiology ; Mycobiome ; Saliva ; microbiology

OBJECTIVETo investigate the distribution pattern of salivary Streptococcus mutans (Sm) level in children and its association with caries status.

METHODSThree hundred and sixty-five 11- 12-year-old children participated in this study. Scores of decayed, missing or filled teeth (DMFT) for the permanent dentition were recorded. Salivary Sm concentrations were determined by species-specific monoclonal antibodies.

RESULTSCaries-affected children harbored more Sm in saliva [5.53 (1.50, 18.00) x 10(7)/L] than their caries-free counterparts [3.42 (1.60, 8.10) x 10(7)/L] (P = 0.002). Salivary Sm concentration tended to rise with the increase of DMFT score. Spearman's correlation coefficient for Sm concentration was 0.136 (P = 0.010). When salivary Sm concentration reached 8.64 x 10(7)/L, children's caries experience doubled.

CONCLUSIONSSalivary Sm level has a skewed distribution among the children studied and associates positively with caries presence. Determination of salivary Sm levels could be used to predict children's caries status.

Child ; Colony Count, Microbial ; DMF Index ; Dental Caries ; epidemiology ; microbiology ; Female ; Humans ; Male ; Prevalence ; Saliva ; microbiology ; Streptococcus mutans ; isolation & purification

OBJECTIVE: The aim of this study was to identify the differences in microbial diversity and community in patients with salivary adenoid cystic carcinoma (SACC). METHODS: Saliva was collected from 13 patients with SACC confirmed by histopathological diagnosis and 10 healthy control subjects. Total metagenomic DNA was extracted. The DNA amplicons of the V3-V4 hypervariable regions of the 16S rRNA gene were generated and subjected to high-throughput sequencing. Microbial diversity and community structure were analyzed with Mothur software. RESULTS: A total of 16 genera of dominant bacteria in the SACC group were found, including Streptococcus (36.68%), Neisseria (8.55%), Prevotella_7 (7.53%), and Veillonella (6.37%), whereas 15 dominant bacteria in the control group were found, including Streptococcus (18.41%), Neisseria (18.20%), Prevotella_7 (8.89%), Porphyromonas (6.20%), Fusobacterium (5.86%) and Veillonella (5.82%). The statistically different phyla between the two groups were Firmicutes, Proteobacteria and Fusobacterium (P<0.05). The statistically different genera between the two groups were Streptococcus, Neisseria and Porphyromonas (P<0.05), and Capnocytophaga was only detected in patients with SACC. CONCLUSIONS Significant differences were observed in the oral microorganisms between the two groups.
Bacteria ; isolation & purification ; Carcinoma, Adenoid Cystic ; microbiology ; Humans ; Porphyromonas ; RNA, Ribosomal, 16S ; Saliva ; Salivary Gland Neoplasms ; microbiology