Distinctive subgingival microbial signatures in older adults with different levels of cognitive function.

AIM: To examine association between subgingival microbial signatures and levels of cognitive impairment in older adults. MATERIALS AND METHODS: We analysed subgingival plaque samples and 16S ribosomal RNA sequences for microbiota among 165 participants (normal controls [NCs]: 40, subjective cognitive decline [SCD]: 40, mild cognitive impairment [MCI]: 49 and dementia: 36). RESULTS: The bacterial richness was lower among individuals with worse cognitive function, and subgingival microbial communities differed significantly among the four groups. Declining cognitive function was associated with decreasing relative abundance of genera Capnocytophaga, Saccharibacteria_genera_incertae_sedis, Lautropia and Granulicatella, and increasing abundance of genus Porphyromonas. Moreover, there were differentially abundant genera among the groups. Random forest model based on subgingival microbiota could distinguish between cognitive impairment and NC (AUC = 0.933, 95% confidence interval 0.873-0.992). Significant correlations were observed between oral microbiota and sex, Montreal Cognitive Assessment (MoCA) score and Mini-Mental State Examination score. Partial correlation analysis showed that Leptotrichia and Burkholderia were closely negatively associated with the MoCA score after adjusting for multiple covariates. Gene function was not significantly different between SCD and NC groups, whereas three homozygous genes were altered in MCI patients and two in dementia patients. CONCLUSIONS: This is the first study to demonstrate an association between the composition, function and metabolic pathways of subgingival microbiota and different levels of cognitive function among older individuals. Future cohort studies should assess its diagnostic usefulness for cognitive impairment.

Periodontal diseases in Thai schoolchildren. Clinical and microbiological observations.

The prevalence of periodontitis among Thai schoolchildren is unknown. In a cross-sectional study, the prevalence and severity of periodontal diseases, in a group of Thai schoolchildren, along with the presence and numbers of bacterial species commonly associated with periodontitis were investigated. A consent form was sent out to 192 schoolchildren in one school (Chanachanupathom School) in Chana, Southern Thailand (in the age range of 12-18 years) and 119 attended for a clinical and microbiological examination. Clinical recordings included number of teeth present, DMFT, plaque index, bleeding index, clinical attachment loss (CAL), and probing pocket depth (PPD). Pooled plaque samples were analyzed with culture and qPCR against bacteria associated with periodontitis. The children had low caries experience (DMFT = 3.2 ± 2.3), poor oral hygiene, high bleeding scores, and 67 (56.3%) had at least one interproximal site with CAL ≥ 1 mm. Thirty-seven (31.1%) of the children were diagnosed with periodontitis stage I, and sixteen (13.4%) were classified as periodontitis Stage II. Aggregatibacter actinomycetemcomitans was sparsely found in all but the healthy clinical groups (gingivitis, periodontitis Stage I and II), while the groups showed a high prevalence of Fusobacterium spp., Prevotella intermedia/nigrescens, and Campylobacter species as well as of the periodontitis-associated species Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. Thai schoolchildren have poor oral hygiene with abundant amounts of plaque and high presence of bleeding. Early onset periodontitis is common but mostly in its mild form and is not associated with the presence of A. actinomycetemcomitans.

Comparative analysis of subgingival microbiota in patients with mild, moderate, and severe chronic periodontitis.

In this study, we explored the suspected pathogens of chronic periodontitis at different stages of occurrence and development. We collected 100 gingival crevicular fluid samples, 27, 27, and 26 from patients with mild, moderate, and severe chronic periodontitis, respectively, and 20 from healthy individuals. Pathogens were detected using a 16S rRNA metagenomic approach. Quantitative Insights in Microbial Ecology, Mothur, and other software were used to analyze the original data, draw relative abundance histograms and heat maps, and calculate flora abundance and diversity indexes. We identified 429 operational taxonomic units, covering 13 phyla, 20 classes, 32 orders, 66 families, and 123 genera from the four groups of samples. Each group showed microbial diversity, and the number of new species of bacterial flora in the gingival crevicular fluid samples gradually increased from the healthy to the severe chronic periodontitis group. There was a significant difference in the relative abundance of the core flora at the phylum, class, order, family, and genus classification levels. Our data indicated a certain correlation between the changes in the subgingival microbial structure and the occurrence and development of chronic periodontitis, which might be able to provide a reference for the diagnosis, treatment and prevention of chronic periodontitis.

Antimicrobial peptides in treatment of Stage III Grade B periodontitis: A randomized clinical trial.

BACKGROUND: To evaluate the effects of antimicrobial peptides (AMPs) on Stage III Grade B periodontitis. METHODS: This trial abided by the principle of consistency test, approved by ethics committee and registered in clinical trials. All qualified 51 patients with Stage III Grade B periodontitis were randomly divided into three groups: SRP group, SRP with minocycline hydrochloride (Mino group) as Control groups, and SRP with AMPs (AMP group) as the Test group. Clinical examinations and subgingival plaques were monitored at baseline and at 7 and 90 days after treatment in the SRP, SRP with AMP and Mino groups. RESULTS: The AMP group (Test group) had a reduced PD (Periodontal probing depth) and an attachment gain significantly higher than SRP and Mino groups (Control groups) at day 90. The abundance of periodontal pathogens was decreased in the AMP group at 7 and 90 days compared with the SRP group and Mino group. Only the AMP group showed an increase the abundance of periodontal probiotics including Capnocytophaga, Gemella, and Lactobacillus at 7 and 90 days. CONCLUSIONS: This study shows that AMPs as an adjunct to SRP promote additional clinical and microbiological benefits in the treatment of Stage III Grade B periodontitis.

Obesity Is Associated with the Severity of Periodontal Inflammation Due to a Specific Signature of Subgingival Microbiota.

The aim of this study was to analyze the link between periodontal microbiota and obesity in humans. We conducted a cohort study including 45 subjects with periodontitis divided into two groups: normo-weighted subjects with a body mass index (BMI) between 20 and 25 kg/m2 (n = 34) and obese subjects with a BMI > 30 kg/m2 (n = 11). Our results showed that obesity was associated with significantly more severe gingival inflammation according to Periodontal Inflamed Surface Area (PISA index). Periodontal microbiota taxonomic analysis showed that the obese (OB) subjects with periodontitis were characterized by a specific signature of subgingival microbiota with an increase in Gram-positive bacteria in periodontal pockets, associated with a decrease in microbiota diversity compared to that of normo-weighted subjects with periodontitis. Finally, periodontal treatment response was less effective in OB subjects with persisting periodontal inflammation, reflecting a still unstable periodontal condition and a risk of recurrence. To our knowledge, this study is the first exploring both salivary and subgingival microbiota of OB subjects. Considering that OB subjects are at higher periodontal risk, this could lead to more personalized preventive or therapeutic strategies for obese patients regarding periodontitis through the specific management of oral microbiota of obese patients.

Potential Impact of Prosthetic Biomaterials on the Periodontium: A Comprehensive Review.

The success of a prosthetic treatment is closely related to the periodontal health of the individual. The aim of this article was to review and present the importance of prosthetic restorative materials on the condition of the periodontium, the changes that occur in the composition of the subgingival microbiota and the levels of inflammatory markers in gingival crevicular fluid. Articles on the influence of different prosthetic restorative materials on subgingival microbiota and proinflammatory cytokines were searched for using the keywords "prosthetic biomaterials", "fixed prosthesis", "periodontal health", "subgingival microbiota", "periodontal biomarkers" and "gingival crevicular fluid" in PubMed/Medline, Science Direct, Scopus and Google Scholar. The type of material used for prosthesis fabrication together with poor marginal and internal fit can result in changes in the composition of the subgingival microbiota, as well as increased accumulation and retention of dentobacterial plaque, thus favoring the development of periodontal disease and prosthetic treatment failure. Biological markers have helped to understand the inflammatory response of different prosthetic materials on periodontal tissues with the main purpose of improving their clinical application in patients who need them. Metal-free ceramic prostheses induce a lower inflammatory response regardless of the fabrication method; however, the use of CAD/CAM systems is recommended for their fabrication. In addition, it is presumed that metal-ceramic prostheses cause changes in the composition of the subgingival microbiota producing a more dysbiotic biofilm with a higher prevalence of periodontopathogenic bacteria, which may further favor periodontal deterioration.

Short-term variation in the subgingival microbiota in two groups of patients treated with clear aligners and vestibular fixed appliances: A longitudinal study.

OBJECTIVE: To evaluate the subgingival microbiological changes during the first six months of therapy with clear aligners (CAs) and fixed appliances (FAs). The null hypothesis was that there would be no microbiological differences between the two. SETTING/SAMPLE: Two groups of patients to be treated, respectively, with CAs (14 patients; 9 females and 5 males; mean age 21 years ± 0.25) and FAs (13 patients; 8 females and 5 males; mean 14 years ± 0.75) were consecutively recruited. MATERIALS AND METHODS: Subgingival microbiological samples were obtained at the right upper central incisor and right first molar at four different time points: before appliance fitting (T0), and at 1 month (T1), 3 months (T3) and 6 months (T6) thereafter. Total bacterial load (TBL) and counts of the bacteria Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Fusobacterium nucleatum, Campylobacter rectus, Treponema denticola and Tannerella forsythia were determined using real-time PCR. RESULTS: Total bacterial load did not vary in the CA group, while a significant increase was detected after 3 and 6 months of treatment in the FA group. Unlike red complex species, C rectus and F nucleatum were often detected: levels remained stable in the CA group but increased progressively in the FA group. CONCLUSION: The type of orthodontic appliance influences the subgingival microbiota. TBL increased in the FA group but not in the CA group, although the levels of the individual periodontal pathogenic bacteria species did not significantly increase during the observation period.

Measuring the subgingival microbiota in periodontitis patients: Comparison of the surface layer and the underlying layers.

Periodontitis is a major cause of tooth loss in adults that initially results from dental plaque. Subgingival plaque pathogenesis is affected by both community composition and plaque structures, although limited data are available concerning the latter. To bridge this knowledge gap, subgingival plaques were obtained using filter paper (the fourth layer) and curette (the first-third layers) sequentially and the phylogenetic differences between the first-third layers and the fourth layer were characterized by sequencing the V3-V4 regions of 16S rRNA. A total of 11 phyla, 148 genera, and 308 species were obtained by bioinformatic analysis, and no significant differences between the operational taxonomic unit numbers were observed for these groups. In both groups, the most abundant species were Porphyromonas gingivalis and Fusobacterium nucleatum. Actinomyces naeslundii, Streptococcus intermedius, and Prevotella intermedia possessed relatively high proportions in the first-third layers; while in the fourth layer, both traditional pathogens (Treponema denticola and Campylobacter rectus) and novel pathobionts (Eubacterium saphenum, Filifactor alocis, Treponema sp. HOT238) were prominent. Network analysis showed that either of them exhibited a scale-free property and was constructed by two negatively correlated components (the pathogen component and the nonpathogen component), while the synergy in the nonpathogen component was lower in the first-third layers than that in the fourth layer. After merging these two parts into a whole plaque group, the negative/positive correlation ratio increased. With potential connections, the first-third layers and the fourth layer showed characteristic key nodes in bacterial networks.

Antimicrobial activity of silver diamine fluoride on human periodontitis microbiota.

Silver diamine fluoride (SDF) has been used in management of dentinal hypersensitivity and dental caries. This in vitro study evaluated the antimicrobial effects of SDF on subgingival microorganisms from severe human periodontitis lesions. Subgingival biofilm specimens from 24 adults with severe periodontitis were mixed in vitro with 19% or 38% SDF or left untreated (n = 24 per group) and then inoculated on enriched Brucella blood agar with anaerobic incubation. Selected red- and orange-complex periodontal pathogens were phenotypically identified in the subgingival specimens, including Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Campylobacter rectus, Fusobacterium nucleatum, and Streptococcus constellatus. Other microbial species recovered from SDF-treated specimens were identified using matrix-assisted laser desorption- ionization time-of-flight mass spectrometry. The SDF-treated specimens yielded significantly lower mean total viable counts and significantly lower mean total cultivable proportional levels of red- and orange-complex periodontal pathogens (0.5%-0.6%) than did untreated specimens (25.9%) (P < 0.001). The only red- and orange-complex species recovered from SDF-treated specimens were P micra (3 patients) and S constellatus (1 patient). The predominant cultivable isolates from SDF-treated specimens were Streptococcus oralis and other streptococci of relatively low periodontopathic and cariogenic potential. No statistically significant in vitro antimicrobial differences were found between 19% and 38% SDF against subgingival biofilm specimens. In this experiment, SDF exhibited substantial in vitro antimicrobial activity against putative periodontal pathogens from severe periodontitis lesions. The suppression of red- and orange-complex periodontal pathogens in subgingival biofilms by SDF treatment, along with the selection of SDF-resistant Streptococcus species that are associated with periodontal health, suggests a potential new therapeutic use for SDF in the management of human periodontal infections.

Subgingival lipid A profile and endotoxin activity in periodontal health and disease.

OBJECTIVES: Regulation of lipopolysaccharide (LPS) chemical composition, particularly its lipid A domain, is an important, naturally occurring mechanism that drives bacteria-host immune system interactions into either a symbiotic or pathogenic relationship. Members of the subgingival oral microbiota can critically modulate host immuno-inflammatory responses by synthesizing different LPS isoforms. The objectives of this study were to analyze subgingival lipid A profiles and endotoxin activities in periodontal health and disease and to evaluate the use of the recombinant factor C assay as a new, lipid A-based biosensor for personalized, point-of-care periodontal therapy. MATERIALS AND METHODS: Subgingival plaque samples were collected from healthy individuals and chronic periodontitis patients before and after periodontal therapy. Chemical composition of subgingival lipid A moieties was determined by ESI-Mass Spectrometry. Endotoxin activity of subgingival LPS extracts was assessed using the recombinant factor C assay, and their inflammatory potential was examined in THP-1-derived macrophages by measuring TNF-α and IL-8 production. RESULTS: Characteristic lipid A molecular signatures, corresponding to over-acylated, bi-phosphorylated lipid A isoforms, were observed in diseased samples. Healthy and post-treatment samples were characterized by lower m/z peaks, related to under-acylated, hypo-phosphorylated lipid A structures. Endotoxin activity levels and inflammatory potentials of subgingival LPS extracts from periodontitis patients were significantly higher compared to healthy and post-treatment samples. CONCLUSIONS: This is the first study to consider structure-function-clinical implications of different lipid A isoforms present in the subgingival niche and sheds new light on molecular pathogenic mechanisms of subgingival biofilm communities. CLINICAL RELEVANCE: Subgingival endotoxin activity (determined by lipid A chemical composition) could be a reliable, bacterially derived biomarker and a risk assessment tool for personalized periodontal care.

Presence of trichomonads in subgingival biofilm of patients with periodontitis: preliminary results.

This study aims to evaluate the prevalence of trichomonads in the subgingival biofilm of patients with periodontitis. Secondarily, the trichomonad presence was related to patient characteristics and periodontal clinical parameters, in order to highlight the factor favoring the development of these protozoans. Subgingival biofilm samples were collected from at least two diseased and one healthy site in 50 patients suffering from periodontitis. Trichomonads were identified using phase contrast microscopy. All patient characteristics and periodontal clinical parameter data were then statistically analyzed. From the 50 patients examined, 195 sites were sampled, including 145 diseased ones. Trichomonads were only observed on 16 of the 145 diseased sites (11%) and none in the other 50 healthy sites. Based on these results, 20% (n = 10) of patients were positive for the presence of trichomonads from at least one of the diseased sites collected. Tooth mobility, substantial supra-gingival dental deposits, and severe clinical attachment loss were statistically associated with trichomonad presence. If the subgingival biofilm of male patients over the age of 50 seemed to be more frequently contaminated with trichomonads, this data was not statistically supported. This preliminary study indicates for the first time that in periodontitis-involved patients, trichomonads are observed in the subgingival biofilm collected from diseased sites with severe bone loss, but not from healthy teeth. Further investigations are needed to fully explore the role of this microorganism in the etiology of periodontal disease.

Clinical and microbiological effects of the adjunctive use of probiotics in the treatment of gingivitis: A randomized controlled clinical trial.

AIM: To evaluate the efficacy of a probiotic combination in the treatment of gingivitis and to assess its impact on the subgingival microbiota. MATERIALS AND METHODS: A placebo-controlled clinical trial was conducted in gingivitis subjects during 6 weeks. Test treatment consisted of the administration of two oral tablets per day containing the probiotic strains Lactobacillus plantarum, Lactobacillus brevis and Pediococcus acidilactici; the control group received the same tablets but without live bacteria. The main outcome variable was the changes in gingival index (GI). Subgingival samples were collected and analysed by quantitative polymerase chain reaction (qPCR) for five putative periodontal pathogens. Outcome variables were compared between and within groups, and multiple regression analysis was performed. RESULTS: A total of 59 patients (29 tests, 30 placebos) were included in the analysis. Both treatment groups experienced a statistically significant improvement in mean GI (p < .0001), but no differences between treatment groups were found for any clinical index. A significantly higher reduction in the number of sites with higher GI scores (GI = 3 at baseline) was observed in the test group. In subgingival samples, a significant reduction in T. forsythia was significant only in the test group (p < .008). CONCLUSIONS: The use of probiotic tablets containing L. plantarum, L. brevis and P. acidilactici did not lead to significant changes in mean GI; although a significant reduction occurred in the number of sites with severe inflammation. Furthermore, the adjunctive use of this probiotic promoted a significant microbiological impact.

Association of metabolic syndrome and chronic periodontitis in Colombians.

BACKGROUND: Metabolic syndrome (MetS) is a common chronic condition that increases the cardiovascular disease risk and is also linked to periodontitis. The study aim was to determine if a relationship exists between MetS and chronic periodontitis in adult Colombians. METHODS: Participants were 220 healthy-gingivitis subjects and 431 periodontitis patients coming from the three largest Colombian cities. Periodontal status and MetS were determined in subjects. Univariate analysis and odds ratio were calculated within the 95 % confidence intervals and chi2 test compared the groups. Variables were compared among the clinical periodontal groups and MetS by Wilcoxon and multivariate analysis, and logistic regression was performed for MetS and periodontitis. RESULTS: MetS had higher prevalence in periodontitis group (6.3 %) versus controls (3.2 %). In multivariate analysis, periodontitis was associated with MetS (adjusted OR = 2.72, 95 % CI 1.09-6.79), glucose intolerance with another component of MetS (adjusted OR = 1.78, 1.16 to 2.72), glucose resistance (adjusted OR = 11.46, 95 % CI 1.41-92.88), smoking (OR = 1.72, 95 % CI 1.09-2.71), and city of origin (2.69, 95 % CI 1.79-4.04). CONCLUSION: The study confirmed the positive association between MetS and periodontitis, being glucose sensitivity the strongly associated component. CLINICAL RELEVANCE: MetS must be taken into account by the dentist when evaluating risk factors for periodontitis, being useful for dentists to evaluate glycemia, lipidic profile, central obesity, and high blood pressure in patients. Interdisciplinary treatment must be recommended when a patient with MetS and periodontitis is being treated.

Low antibiotic resistance among anaerobic Gram-negative bacteria in periodontitis 5 years following metronidazole therapy.

The objective of this study was to assess antibiotic susceptibility among predominant Gram-negative anaerobic bacteria isolated from periodontitis patients who 5 years prior had been subject to mechanical therapy with or without adjunctive metronidazole. One pooled sample was taken from the 5 deepest sites of each of 161 patients that completed the 5 year follow-up after therapy. The samples were analyzed by culture. A total number of 85 anaerobic strains were isolated from the predominant subgingival flora of 65/161 patient samples, identified, and tested for antibiotic susceptibility by MIC determination. E-tests against metronidazole, penicillin, amoxicillin, amoxicillin + clavulanic acid and clindamycin were employed. The 73/85 strains were Gram-negative rods (21 Porphyromonas spp., 22 Prevotella/Bacteroides spp., 23 Fusobacterium/Filifactor spp., 3 Campylobacter spp. and 4 Tannerella forsythia). These were all isolated from the treated patients irrespective of therapy procedures (+/-metronidazole) 5 years prior. Three strains (Bifidobacterium spp., Propionibacterium propionicum, Parvimonas micra) showed MIC values for metronidazole over the European Committee on Antimicrobial Susceptibility Testing break point of >4 µg/mL. All Porphyromonas and Tannerella strains were highly susceptible. Metronidazole resistant Gram-negative strains were not found, while a few showed resistance against beta-lactam antibiotics. In this population of 161 patients who had been subject to mechanical periodontal therapy with or without adjunct metronidazole 5 years prior, no cultivable antibiotic resistant anaerobes were found in the predominant subgingival microbiota.

Characterization of A. actinomycetemcomitans strains in subgingival samples from periodontitis subjects in Morocco.

OBJECTIVE: Aggregatibacter actinomycetemcomitans, specially its highly leucotoxic strain (JP2 clone), represents an etiological factor for the onset and progression of aggressive types of periodontitis. The aims of this investigation were to investigate the most relevant periodontal pathogens in the subgingival microbiota of periodontitis patients from Morocco and to describe the clinical and microbiological characteristics of subjects positive for A. actinomycetemcomitans, including serotype, leukotoxin gene, and operon of the cytolethal distending toxin (cdt) distribution. MATERIAL AND METHODS: In consecutive Moroccan subjects diagnosed of periodontitis, subgingival samples were taken and processed by culture. From the positive samples for A. actinomycetemcomitans, one to three isolates were subcultured and characterized by means of polymerase chain reaction (PCR), assessing their specific serotype distribution, the variation in the sequences of the leukotoxin gene, and the operon of the cdt. RESULTS: Twenty-one (35.6 %) out of 59 periodontitis patients harbored A. actinomycetemcomitans. These patients demonstrated statistically significant deeper pockets (p = 0.035) and higher proportions of P. micra (p = 0.045) than did the negative group. The 39 studied isolates were serotype "b"; in 16 out of 17 patients, there was mono-colonization with this serotype. Five isolates, from two patients, presented the 530-bp deletion in the leukotoxin's promoter region. Thirty-two isolates (78 % of the strains) were cdt-positive. CONCLUSION: A. actinomycetemcomitans was frequently found (35.6 %) in our sample. All strains were serotype "b," and most (78 %) were also cdt-positive. The JP2 strain type was only detected in 12.2 % of the strains. CLINICAL RELEVANCE: A. actinomycetemcomitans can be frequently found in Morocco. This fact can influence the therapeutic approach of this type of patients.

Effect of mobile app-based oral hygiene instructions on clinical parameters, oral bacterial diversity, and composition of subgingival microbiota in periodontitis patients.

Introduction: Oral hygiene instruction (OHI) is essential during periodontitis treatment. Various OHI approaches have been explored, including mobile apps. Objective: To evaluate the mobile app-based OHI's effect on periodontitis management by analyzing clinical parameters and subgingival microbiota. Methods: Forty-four periodontitis patients were randomly assigned into two groups. The test group (n = 22) received scaling and root planing (SRP), OHI, and mobile app-based OHI, whereas the control group (n = 22) received SRP and OHI. Full mouth plaque score (FMPS), bleeding on probing (BOP) and probing pocket depth at the sampling sites (site-PPD) were assessed at baseline, one- and three-month visits. The 16S rRNA next-generation sequencing (NGS) was used to analyze subgingival plaque samples. Results: Significant reduction in FMPS, BOP, and site-PPD at one- and three-month visits compared to baseline (p < 0.001) with no significant differences across groups (p > 0.05). In test groups, intra-group analysis showed better improvement in BOP and site-PPD (p < 0.05) than control. The diversity and composition of subgingival microbiota did not differ between groups or timepoints (p > 0.05). Conclusions: Mobile app-based OHI showed no superior effects on improving clinical parameters and subgingival microbiota compared to conventional OHI. Further investigation into its long-term impact on periodontitis treatment is needed.

Accelerated corrosion of 316L stainless steel in a simulated oral environment via extracellular electron transfer and acid metabolites of subgingival microbiota.

316L stainless steel (SS) is widely applied as microimplant anchorage (MIA) due to its excellent mechanical properties. However, the risk that the oral microorganisms can corrode 316L SS is fully neglected. Microbiologically influenced corrosion (MIC) of 316L SS is essential to the health and safety of all patients because the accelerated corrosion caused by the oral microbiota can trigger the release of Cr and Ni ions. This study investigated the corrosion behavior and mechanism of subgingival microbiota on 316L SS by 16S rRNA and metagenome sequencing, electrochemical measurements, and surface characterization techniques. Multispecies biofilms were formed by the oral subgingival microbiota in the simulated oral anaerobic environment on 316L SS surfaces, significantly accelerating the corrosion in the form of pitting. The microbiota samples collected from the subjects differed in biofilm compositions, corrosion behaviors, and mechanisms. The oral subgingival microbiota contributed to the accelerated corrosion of 316L SS via acidic metabolites and extracellular electron transfer. Our findings provide a new insight into the underlying mechanisms of oral microbial corrosion and guide the design of oral microbial corrosion-resistant materials.

Analysis of subgingival microbiota and IL-1ß, TNF-α and CX3CL1 levels in gingival crevicular fluid of fixed dental prostheses.

Prosthetic biomaterials can affect the composition of the subgingival microbiota and consequently the production of proinflammatory cytokines, causing damage to the periodontium. A total of 40 patients were divided into two groups: 20 with monolithic zirconia (MZ) prostheses and 20 with porcelain fused to metal (PFM) with nickel-chromium (Ni-Cr) alloy prostheses. Subgingival plaque and gingival crevicular fluid samples were taken. The Checkerboard technique for DNA-DNA hybridization and the enzyme-linked immunosorbent assay technique were performed. Teeth with MZ presented a lower percentage of bleeding on probing and tooth mobility compared to teeth with PFM with Ni-Cr alloy. Prosthodontic teeth harbored higher total levels of the 18 bacterial species than non-prosthodontic teeth. There was a higher prevalence of S. gordonii and V. parvula species in PFM with Ni-Cr alloy compared to MZ. There was an increase in IL-1ß, TNF-α and CX3CL1 levels in PFM with Ni-Cr alloy compared to MZ. MZ is a candidate biomaterial with fewer negative effects on the periodontium, allowing for longer prostheses longevity in the mouth.

Influence of obesity on subgingival microbiota composition in subjects with different periodontal status: a systematic review.

Objective: This systematic review aimed to investigate the changes in the composition of the subgingival microbiota among subjects with normo-weight, overweight and obesity, in conditions of periodontal health and disease. Materials and Methods: The protocol for this study was designed following PRISMA guidelines. Records were identified using different search engines (PubMed/MedLine, Scopus and Web of Science). Observational studies, in human subjects diagnosed with obesity (BMI >30kg/m2) and periodontal disease (gingivitis and periodontitis), on the analysis of subgingival microbiota were selected. Eight articles were included. Results: The subgingival microbiota of 1,229 subjects (n=894 exposure group and n=335 control group) was analyzed. Periodontal pathogens were the most common bacteria detected in subjects with obesity and periodontitis (Porphyromonas gingivalis, Tannerella forsythia, Campylobacter gracilis, Eubacterium nodatum, Fusobacterium nucleatum spp. vincentii, Parvimonas micra, Prevotella intermedia, Campylobacter rectus, and Aggregatibacter actinomycetemcomitans), as along with some accessory pathogens such as: Streptococcus gordonii, and Veillonella parvula that favor the virulence of late colonizers. Conclusions: Although there are evident alterations in the composition of the subgingival microbiota in subjects with obesity and periodontitis, it is still a challenge to identify a specific pattern of microbiota in these subjects. If associations between subgingival plaque microorganisms and obesity are confirmed, microbiome analysis could be a useful tool to improve preventive measures and the management of people with obesity.

Objetivo: Esta revisión sistemática tuvo como objetivo investigar los cambios en la composición de la microbiota subgingival entre sujetos con normopeso, sobrepeso y obesidad, en condiciones de salud y enfermedad periodontal. Materiales y métodos: El protocolo de este estudio se diseñó siguiendo las directrices PRISMA. Los registros se identificaron utilizando diferentes motores de búsqueda (PubMed/MedLine, Scopus y Web of Science). Se seleccionaron estudios observacionales en sujetos humanos diagnosticados con obesidad (IMC >30kg/m2) y enfermedad periodontal (gingivitis y periodontitis), sobre el análisis de la microbiota subgingival. Se incluyeron ocho artículos. Resultados: Se analizó la microbiota subgingival de 1229 sujetos (n = 894 grupo de exposición y n = 335 grupo de control). Los patógenos periodontales fueron las bacterias más comunes detectadas en los sujetos con obesidad y periodontitis (Porphyromonas gingivalis, Tannerella forsythia, Campylobacter gracilis, Eubacterium nodatum, Fusobacterium nucleatum spp. vincentii, Parvimonas micra, Prevotella intermedia, Campylobacter rectus y Aggregatibacter actinomycetemcomitans), junto con algunos patógenos accesorios, como Streptococcus gordonii y Veillonella parvula, que favorecen la virulencia de los colonizadores tardíos. Conclusiones: Aunque existen alteraciones evidentes en la composición de la microbiota subgingival en sujetos con obesidad y periodontitis, sigue siendo un reto identificar un patrón específico de microbiota en ellos. Si se confirman las asociaciones entre los microorganismos de la placa subgingival y la obesidad, el análisis del microbioma podría ser una herramienta útil para mejorar las medidas preventivas y el manejo de las personas con obesidad.

Metabolism of periodontal pathobionts: Their regulatory roles in the dysbiotic microbiota.

The onset and development of periodontitis centers around microbiota dysbiosis and disrupted host responses. Dynamic metabolic activities of the subgingival microbiota modify the polymicrobial community, shape the microenvironment, and modulate the host response. A complicated metabolic network exists in interspecies interactions between periodontal pathobionts and commensals, which can lead to the development of dysbiotic plaque. Dysbiotic subgingival microbiota undergo metabolic interactions with the host and disrupt host-microbe equilibrium. In this review, we discuss the metabolic profiles of the subgingival microbiota, the metabolic crosstalk in polymicrobial communities, including pathobionts and commensals, and the metabolic interactions between microbes and the host.