Possible Periodontal Pathogens Associated With Clinical Symptoms of Periodontal Disease in Japanese High School Students

Structure and Function of Oral Microbial Community in Periodontitis Based on Integrated Data

Objective

Microorganisms play a key role in the initiation and progression of periodontal disease. Research studies have focused on seeking specific microorganisms for diagnosing and monitoring the outcome of periodontitis treatment. Large samples may help to discover novel potential biomarkers and capture the common characteristics among different periodontitis patients. This study examines how to screen and merge high-quality periodontitis-related sequence datasets from several similar projects to analyze and mine the potential information comprehensively.

Methods

In all, 943 subgingival samples from nine publications were included based on predetermined screening criteria. A uniform pipeline (QIIME2) was applied to clean the raw sequence datasets and merge them together. Microbial structure, biomarkers, and correlation network were explored between periodontitis and healthy individuals. The microbiota patterns at different periodontal pocket depths were described. Additionally, potential microbial functions and metabolic pathways were predicted using PICRUSt to assess the differences between health and periodontitis.

Results

The subgingival microbial communities and functions in subjects with periodontitis were significantly different from those in healthy subjects. Treponema, TG5, Desulfobulbus, Catonella, Bacteroides, Aggregatibacter, Peptostreptococcus, and Eikenella were periodontitis biomarkers, while Veillonella, Corynebacterium, Neisseria, Rothia, Paludibacter, Capnocytophaga, and Kingella were signature of healthy periodontium. With the variation of pocket depth from shallow to deep pocket, the proportion of Spirochaetes, Bacteroidetes, TM7, and Fusobacteria increased, whereas that of Proteobacteria and Actinobacteria decreased. Synergistic relationships were observed among different pathobionts and negative relationships were noted between periodontal pathobionts and healthy microbiota.

Conclusion

This study shows significant differences in the oral microbial community and potential metabolic pathways between the periodontitis and healthy groups. Our integrated analysis provides potential biomarkers and directions for in-depth research. Moreover, a new method for integrating similar sequence data is shown here that can be applied to other microbial-related areas.

Gingival tissue human beta-defensin levels in relation to infection and inflammation

AIM

To profile gingival tissue levels of human beta-defensin (hBD)-2 and hBD-3 in relation to gingival inflammation, Th17-related cytokine concentrations, Porphyromonas gingivalis counts, and gingipain and total protease activities.

MATERIALS AND METHODS

Gingival tissue and subgingival plaque samples were collected from 21 periodontitis patients including 48 periodontal pocket sites with marginal, mild, or moderate to severe inflammation. hBD levels were determined by immunodetection, P. gingivalis counts with real-time polymerase chain reaction, protease activities with fluorogenic substrates, and cytokine concentrations with Luminex technique. Data were statistically analysed using Kruskal-Wallis and Mann-Whitney U tests and Spearman correlation coefficients.

RESULTS

Subgingival plaque counts of P. gingivalis (p = .001) and gingipain activity (p < .001), as well as interleukin (IL)-1β (p = .012), IL-10 (p = .024), IL-17A (p = .002), IL-17F (p = .006), and IL-23 (p = .036) concentrations were elevated in severely inflamed sites, whereas no change was observed in hBD-2 and hBD-3 levels. Negative correlations were found between protease activity and hBD-2 (p = .033) and hBD-3(p = .003) levels.

CONCLUSIONS

Shift in gingival inflammation from marginal to mild stage is related to elevations in subgingival plaque P. gingivalis counts and gingipain activity, but not to tissue hBD levels. Negative correlations between hBDs and total protease activity suggest the degradation of these antimicrobial peptides in progressed inflammation.

Cross-sectional analysis of risk factors for subclinical periodontitis; active matrix metalloproteinase-8 as a potential indicator in initial periodontitis in adolescents

BACKGROUND

The aim of this study was to investigate how different patient-related risk indicators might be associated with the odds of developing subclinical periodontitis in adolescents.

METHODS

This cross-sectional study included 252 Finnish individuals aged 15 to 16 years, of whom 141 were boys and 111 girls. A specially trained dentist performed clinical examinations: measurements included periodontal indexes (bleeding on probing, visible plaque index, root calculus, and probing depth, smoking by pack-years, periodontal bacteria (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, Prevotella nigrescens, and Treponema denticola) and the potential salivary periodontal biomarkers (active matrix metalloproteinase-8 [aMMP-8], polymorphonuclear leukocyte elastase [PMN elastase], and total protein, albumin, immunoglobulin A, immunoglobulin G, and immunoglobulin M). Results were analyzed by ordinal logistic regression, one-way analysis of variance, Fisher exact test, and Kruskal-Wallis H test.

RESULTS

The main finding of this study was that subclinical periodontitis in adolescents was statistically significantly associated with elevated salivary aMMP-8 but not with PMN elastase. Also, adolescents with subclinical periodontitis had statistically significantly higher levels of bleeding on probing, root calculus, and dental plaque than adolescents without subclinical periodontitis.

CONCLUSIONS

We suggest that the main risk factor for subclinical periodontitis in adolescents is the partly calcified, dysbiotic bacterial biofilm, which interacts with the immune defenses of the host; this leads to gingival inflammation and eventually to deepening periodontal pockets. This proinflammatory subclinical periodontitis stage, which represents stage I periodontitis in the new classification, is reflected as elevated salivary aMMP-8 levels in oral fluids.

Assessing Bone Type of Implant Recipient Sites by Stereomicroscopic Observation of Bone Core Specimens: A Comparison With the Assessment Using Dental Radiography

BACKGROUND

The aim of the study is to determine if bone quality evaluation of surgically obtained bone core specimens using a stereomicroscope is reliable for determining bone quality at implant recipient sites.

METHODS

Bone quality was presurgically assessed in 122 edentulous ridges obtained from 62 patients using periapical radiographs and categorized according to the Lekholm and Zarb classification. During surgery, bone specimens were trephined, and bone types were immediately classified using a stereomicroscope. Microarchitectural characteristics of bone cores were evaluated after being scanned using microcomputed tomography (micro-CT).

RESULTS

Bone types of implant sites categorized from radiography and stereomicroscope had statistically similar distribution but poor interrater agreement. Using micro-CT, maxillae and mandibles showed significant differences in microarchitectural characteristics of bone cores. Bone volume (BV), total volume (TV), and trabecular thickness (Tb.Th) increased, whereas bone surface density (BS/BV) and open porosity (Po.[Op]) decreased in mandibular bone cores compared with those in maxillary bone cores. Moreover, micro-CT values of BV/TV and Po.(Op) statistically correlated with bone types assessed by stereomicroscopy, particularly in mandibles (adjusted means of BV/TV of Type 2 to 4 versus Type 1 decreasing from -9.88%, -15.09%, -29.31%; those of Po.(Op) ranged from 9.77%, 15.06%, 29.52% in an upward trend). However, such correlations were not found in maxillae or when bone types were classified using periapical radiographs.

CONCLUSIONS

Caution is needed when using presurgical periapical radiographs to predict bone quality at implant recipient sites. Surgically preserved bone core specimens, whenever obtainable, might offer additional information to accurately assess bone quality, particularly at mandibular implant sites.

Serum C-reactive protein and immunoglobulin G antibodies to periodontal pathogens may be effect modifiers of periodontitis and hyperglycemia

BACKGROUND

Serum C-reactive protein (CRP) is elevated in both periodontitis and type 2 diabetes mellitus through inflammation. Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis have been found in periodontal pockets in patients with diabetes. This study examines effect modification by examining the extent to which the associations between periodontitis and hyperglycemia were different by levels of serum CRP and periodontal pathogens.

METHODS

Blood samples with plasma were evaluated for immunoglobulin G antibodies, CRP, and fasting glucose from 5,731 participants ≥ 20 years old receiving oral examinations and providing other health-related data from the National Health and Nutrition Examination Survey III. The study participants were classified into quartiles of probing depth (PD) and clinical attachment level (CAL). The first quartile was the reference. Logistic regression models with survey procedures were used to explore the roles of inflammation levels from serum CRP and periodontal pathogens on the relations with periodontitis, including PD, CAL, and hyperglycemia, and their joint associations with interaction terms.

RESULTS

Stronger associations between PD and diabetes existed in people having elevated CRP and titers for P. gingivalis; odds ratios comparing extreme quartiles of PD were 1.31 and 3.40 in the groups with low and high CRP, respectively, and 1.28 and 2.96 in groups with low and high titers for P. gingivalis, respectively. The joint association patterns were similar for CAL and diabetes.

CONCLUSIONS

The strengths of association between periodontitis and diabetes were stronger in people having elevated serum CRP and P. gingivalis titers. This may suggest that chronic inflammatory conditions could increase the impact of periodontitis on hyperglycemic status.

Correlation of age with distribution of periodontitis-related bacteria in Japanese dogs

We analyzed the distribution of 11 periodontitis-related bacterial species in dental plaque collected from 176 Japanese dogs divided into young (less than 2 years of age), middle-aged (2-7 years of age) and elderly (more than 8 years of age) groups using a polymerase chain reaction method. Clinical examination revealed that no dogs in the young group were affected by periodontitis, whereas the rates for gingivitis and periodontitis were high in the middle-aged and elderly groups. In addition, the total numbers of bacterial species in the middle-aged and elderly groups were significantly greater than in the young group. Our findings suggest that age is an important factor associated with the distribution of periodontitis-related bacteria and periodontal conditions in dogs.

Molecular detection of human periodontal pathogens in oral swab specimens from dogs in Japan

Periodontal diseases are known to be major diseases in humans, and are also common in dogs. The purpose of the present study was to analyze the distribution of periodontitis-related bacterial species using oral swab specimens collected from 26 pet dogs. The distribution of an animal gingival organism Porphyromonas gulae, in addition to 10 human periodontitis-related bacterial species, including Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Capnocytophaga ochracea, Capnocytophaga sputigena, Prevotella intermedia, Prevotella nigrescens, Aggregatibacter actinomycetemcomitans, Campylobacter rectus, and Eikenella corrodens, were evaluated by polymerase chain reaction with species-specific sets of primers. Porphyromonas gulae, Tannerella forsythia and Campylobacter rectus were detected in almost all dogs analyzed, all of which should be regarded as common members of oral flora in dogs. Then, isolation and identification of the Porphyromonas species in swab specimens were performed. There were 35 strains isolated from 22 dogs, and broad-range polymerase chain reaction and sequencing methods revealed that approximately 70% of them were Porphyromonas gulae. In contrast, the frequency of Porphyromonas gingivalis was extremely low. These findings indicate the presence of specific periodontitis-related pathogens in pet dogs, especially Porphyromonas gulae.

Transferrin as a source of iron for Campylobacter rectus

Background and Objective

Campylobacter rectus is considered as one of the bacterial species of etiological importance in periodontitis. Iron-containing proteins such as transferrin are found in periodontal sites and may serve as a source of iron for periodontopathogens. The aim of this study was to investigate the capacity of C. rectus to assimilate transferrin-bound iron to support its growth.

Design

Growth studies were performed in broth media pretreated with an iron-chelating resin and supplemented with various iron sources. The uptake of iron by C. rectus was monitored using ⁵⁵Fe-transferrin. Transferrin-binding activity was assessed using a microplate assay while the degradation of transferrin and iron removal was evaluated by polyacrylamide gel electrophoresis. A colorimetric assay was used to determine ferric reductase activity.

Results

Holotransferrin (iron-saturated form) but not apotransferrin (iron-free form) was found to support growth of C. rectus in an iron-restricted culture medium. Incubation of holotransferrin with cells of C. rectus resulted in removal of iron from the protein. A time dependent intracellular uptake of iron by C. rectus cells from ⁵⁵Fe-transferrin was demonstrated. This uptake was significantly increased when bacteria were grown under an iron-limiting condition. Cells of C. rectus did not show transferrin-binding activity or proteolytic activity toward transferrin. However, a surface-associated ferric reductase activity was demonstrated.

Conclusion

To survive and multiply in periodontal sites, periodontopathogens must possess efficient iron-scavenging mechanisms. In this study, we showed the capacity of C. rectus to assimilate iron from transferrin to support its growth. The uptake of iron appears to be dependent on a ferric reductive pathway.

Effect of smoking on subgingival microflora of patients with periodontitis in Japan

Background

Smoking is a risk factor for periodontitis. To clarify the contribution of smoking to periodontitis, it is essential to assess the relationship between smoking and the subgingival microflora. The aim of this study was to gain an insight into the influence of smoking on the microflora of Japanese patients with periodontitis.

Methods

Sixty-seven Japanese patients with chronic periodontitis (19 to 83 years old, 23 women and 44 men) were enrolled in the present study. They consisted of 30 smokers and 37 non-smokers. Periodontal parameters including probing pocket depth (PPD) and bleeding on probing (BOP) and oral hygiene status were recorded. Detection of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum/periodonticum, Treponema denticola and Campylobacter rectus in subgingival plaque samples was performed by polymerase chain reaction. Association between the detection of periodontopathic bacteria and smoking status was analyzed by multiple logistic regression analysis and chi-square test.

Results

A statistically significant association was found between having a PPD ≥ 4 mm and detection of T. denticola, P. intermedia, T. forsythia, or C. rectus, with odds ratios ranging from 2.17 to 3.54. A significant association was noted between BOP and the detection of C. rectus or P. intermedia, and smoking, with odds ratios ranging from 1.99 to 5.62. Prevalence of C. rectus was higher in smokers than non-smokers, whereas that of A. actinomycetemcomitans was lower in smokers.

Conclusions

Within limits, the analysis of the subgingival microbial flora in smokers and non-smokers with chronic periodontitis suggests a relevant association between smoking and colonization by the specific periodontal pathogens including C. rectus.

Distribution of periodontopathic bacterial species in Japanese children with developmental disabilities

Background

Recent developments in molecular biological techniques have enabled rapid detection of periodontopathic bacterial species in clinical specimens. Accumulated evidence suggests that detection of specific bacterial species enables identification of subjects at high risk for the onset of periodontitis. We investigated the distribution of 10 selected periodontopathic bacterial species in dental plaque specimens obtained from children with disabilities who were attending daycare centers.

Methods

A total of 187 children (136 boys, 51 girls) aged 1-6 years old and diagnosed with such disabilities as mental retardation, cerebral palsy, and autism, participated in the study. Subgingival dental plaque specimens were collected from the buccal side of the maxillary left second primary molar after a clinical examination. Bacterial DNA was extracted from the specimens and PCR analyses were carried out to detect 10 selected periodontopathic species using specific primers for each. In addition, statistical analyses were performed to analyze the correlations among clinical parameters and the detected species.

Results

The most frequently detected species was Capnocytophaga sputigena (28.3%), followed by Aggregatibacter actinomycetemcomitans (20.9%) and Campylobacter rectus (18.2%). Eikenella corrodens, Capnocytophaga ochracea, and Prevotella nigrescence were detected in approximately 10% of the specimens, whereas Treponema denticola, Tannerella forsythia, and Prevotella intermedia were rarely found, and Porphyromonas gingivalis was not detected in any of the subjects. The total numbers of detected species were positively correlated with the age of the subjects. There were 10 subjects with positive reactions for T. denticola and/or T. forsythia, in whom the total number of bacterial species was significantly higher as compared to the other subjects. Furthermore, subjects possessing C. rectus showed significantly greater values for periodontal pocket depth, gingival index, and total number of species.

Conclusion

We found that approximately one-fourth of the present subjects with disabilities who possessed at least one of T. denticola, T. forsythia, and C. rectus were at possible risk for periodontitis. Follow-up examinations as well as preventive approaches should be utilized for such individuals.

Distribution of 10 periodontal bacteria in saliva samples from Japanese children and their mothers

OBJECTIVE

We analyzed the distribution of 10 periodontal bacteria species (Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia, Prevotella nigrescens, Campylobacter rectus, Eikenella corrodens, Actinobacillus actinomycetemcomitans, Capnocytophaga ochracea, Capnocytophaga sputigena, and Treponema denticola) in children, and then compared their distribution in those children and their mothers, with special attention given to three of the species known as the red complex (P. gingivalis, T. forsythensis, and T. denticola) whose presence has been shown to be associated with conditions related to periodontal diseases.

METHODS

One hundred thirteen pairs of children and their mothers were randomly selected from patients treated at the Pedodontic Clinic of Osaka University Dental Hospital. Saliva samples were taken at the second visit prior to receiving professional tooth brushing instruction. Genomic DNA was extracted from each saliva sample, followed by a polymerase chain reaction assay with species-specific sets of primers.

RESULTS

A. actinomycetemcomitans was the most frequently detected species in the mothers, followed by C. sputigena, P. gingivalis, and T. forsythensis, while C. sputigena had the highest detection rate, followed by A. actinomycetemcomitans and T. denticola in the children. The detection rate of the red complex species in children whose mothers possessed the same species was significantly higher than in those whose mothers did not possess them.

CONCLUSIONS

Our results indicate a correlation between the presence of periodontal bacteria in children and their mothers, while the presence of red complex bacteria in children was highly associated with that in their mothers.