Quantification of Porphyromonas gingivalis and fimA genotypes in smoker chronic periodontitis

Short term effect of antimicrobial photodynamic therapy and probiotic L. salivarius WB21 on halitosis: A controlled and randomized clinical trial

OBJECTIVE

This study aimed to evaluate the effect of antimicrobial photodynamic therapy (aPDT) and the use of probiotics on the treatment of halitosis.

METHODS

Fifty-two participants, aged from 18 to 25 years, exhaling sulfhydride (H2S) ≥ 112 ppb were selected. They were allocated into 4 groups (n = 13): Group 1: tongue scraper; Group 2: treated once with aPDT; Group 3: probiotic capsule containing Lactobacillus salivarius WB21 (6.7 x 108 CFU) and xylitol (280mg), 3 times a day after meals, for 14 days; Group 4: treated once with aPDT and with the probiotic capsule for 14 days. Halimetry with gas chromatography (clinical evaluation) and microbiological samples were collected from the dorsum of the tongue before and after aPDT, as well as after 7, 14, and 30 days. The clinical data failed to follow a normal distribution; therefore, comparisons were made using the Kruskal-Wallis test (independent measures) and Friedman ANOVA (dependent measures) followed by appropriate posthoc tests, when necessary. For the microbiological data, seeing as the data failed to follow a normal distribution, the Kruskal-Wallis rank sum test was performed with Dunn's post-test. The significance level was α = 0.05.

RESULTS

Clinical results (halimetry) showed an immediate significant reduction in halitosis with aPDT (p = 0.0008) and/or tongue scraper (p = 0.0006). Probiotics showed no difference in relation to the initial levels (p = 0.7530). No significant differences were found in the control appointments. The amount of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola were not altered throughout the analysis (p = 0.1616, p = 0.2829 and p = 0.2882, respectively).

CONCLUSION

There was an immediate clinical reduction of halitosis with aPDT and tongue scraping, but there was no reduction in the number of bacteria throughout the study, or differences in the control times, both in the clinical and microbiological results. New clinical trials are necessary to better assess the tested therapies.

TRIAL REGISTRATION

Clinical Trials NCT03996044.

Histopathological and immunohistochemical study of periodontal changes in chronic smokers

Periodontal disease is a chronic inflammatory, multifactorial condition, that, in the absence of an early and adequate treatment, may lead to a progressive damaging of the alveolar tissues that support the teeth (periodontal ligament, cement and alveolar bone) followed by teeth mobility and, subsequently, their loss. Periodontal disease is one of the most common inflammatory disease affecting adult individuals all over the world, being considered a real worldwide pandemic. This disease may influence the progression of certain systemic diseases: diabetes mellitus, cardiovascular diseases, ischemic cardiomyopathy, myocardial infarction, stroke, neurodegenerative diseases, chronic kidney diseases, cancer, etc. The association between smoking and periodontal disease was described in numerous clinical and epidemiological studies, suggesting that products derived from tobacco burning may change the clinical aspects and the disease progression. The present study analyzed microscopically and immunohistochemically 58 periodontal fragments, from 50 patients, chronic smokers, clinically diagnosed with severe periodontitis. There were highlighted major changes in the gingival epithelium (epithelium thickening, acanthosis, intraepithelial edema, infiltrates of neutrophils or lymphocytes, epithelial necrosis), in the periodontal conjunctive tissue (more or less intense inflammatory infiltrates, microhemorrhages, vascular congestion, intense immunohistochemical expression for some matrix metalloproteinases). The periodontal changes may be the expression of both toxic factors present in tobacco smoke and due to the changes caused by tobacco in the microbial flora of the oral cavity.

Effect of antimicrobial photodynamic therapy with red led and methylene blue on the reduction of halitosis: controlled microbiological clinical trial

To determine the effect of antimicrobial photodynamic therapy (aPDT) using a red light-emitting diode (LED) on the reduction of halitosis and microbiological levels in the tongue coating immediately after irradiation, 7, 14, and 30 days after treatment. Forty-five young adults diagnosed with halitosis were allocated to three groups: G1, aPDT with 0.005% methylene blue and red LED (660 nm, four irradiation points, 90 s per point, power of 400 mW, 36 J per point, radiant exposure of 95 J/cm², continuous wave); G2, tongue scraping; and G3, tongue scraping and aPDT. Gas chromatography was performed before and immediately after treatment, as well as at the different follow-up times. Microbiological samples were collected at the same times from the dorsum of the tongue, and bacteria were quantified in the samples using real-time PCRq. The Wilcoxon test was used for the intragroup analyses, and the Kruskal-Wallis test was used for the intergroup analyses. In the intragroup analyses, differences were found before and immediately after treatment in all groups (p < 0.05). The effect was maintained after 7 days only in the tongue scraping group (p < 0.05). In the intergroup analysis, no statistically significant differences were found among the groups (p > 0.05). For the microbiological analyses, no statistically significant differences were found in the groups/bacteria that were analyzed (p > 0.05). aPDT using a red LED and 0.005% methylene blue caused an immediate reduction in halitosis, but the effect was not maintained after 7, 14, or 30 days. No reduction occurred in the number of bacteria investigated or the quantification of universal 16S rRNA. ClinicalTrials.gov Identifier: NCT03656419.

The prevalence of fimA genotypes of Porphyromonas gingivalis in patients with chronic periodontitis: A meta-analysis

FimA is an important virulence factor of Porphyromonas gingivalis (P. gingivalis). According to its DNA sequence, the fimA genotype of P. gingivalis can be divided into six categories (I, Ib, Ⅱ, III, IV, V). The fimA gene may be a key factor in the diversity of virulence found in P. gingivalis. Moreover, the role fimA plays in the pathogenesis of P. gingivalis is closely associated with periodontitis, making it an important factor of study for disease prevention and treatment. In this study, the prevalence of fimA genotypes of P. gingivalis in patients with periodontal diseases was evaluated by meta-analysis. The Embase and PubMed databases were searched for articles from 1999 to 2019 using the following search terms: Porphyromonas gingivalis or P. gingivalis; periodontitis or chronic periodontal disease; fimA or fimA genotype. The reference lists of relevant published articles were searched manually. A total of 17 studies were included in this report. A statistical software package (Stata, version 11.0/mp, StataCorp) was utilized to calculate and analyze the P. gingivalis fimA genotypes for each combined incidence estimate. The pooled rates of fimA Ⅰ, fimA Ib, fimA Ⅱ, fimA Ⅲ, fimA Ⅳ and fimA Ⅴ genotypes of P. gingivalis were 8.4% (95% CI: 5.7-11.1), 11.7% (95% CI: 7.4-16), 42.9% (95% CI: 34.2-51.7), 6.5% (95% CI: 5.1-7.9), 17.8% (95% CI: 9.0-26.5), and 3.2% (95% CI: 1.6-4.9), respectively. This study showed that the fimA Ⅱ and fimA Ⅳ genotypes of P. gingivalis are highly present in patients with periodontal disease. Therefore, these two genotypes may be related to the pathogenesis and progress of periodontal disease, one of the main risk factors of periodontitis.

Assessment of the antibacterial, antivirulence, and action mechanism of Copaifera pubiflora oleoresin and isolated compounds against oral bacteria

The microorganisms that constitute the oral microbiome can cause oral diseases, including dental caries and endodontic infections. The use of natural products could help to overcome bacterial resistance to the antimicrobials that are currently employed in clinical therapy. This study assessed the antimicrobial activity of the Copaifera pubiflora oleoresin and of the compounds isolated from this resin against oral bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays provided values ranging from 6.25 to > 400 μg/mL for the C. pubiflora oleoresin and its isolated compounds. The fractional inhibitory concentration index (FICI) assay showed that the oleoresin and chlorhexidine did not act synergistically. All the tested bacterial strains formed biofilms. MICB₅₀ determination revealed inhibitory action: values varied from 3.12-25 μg/mL for the oleoresin, and from 0.78 to 25 μg/mL for the ent-hardwickiic acid. Concerning biofilm eradication, the C. pubiflora oleoresin and hardwickiic acid eradicated 99.9 % of some bacterial biofilms. Acid resistance determination showed that S. mutans was resistant to acid in the presence of the oleoresin and ent-hardwickiic acid at pH 4.0, 4.5, and 5.0 at all the tested concentrations. Analysis of DNA/RNA and protein release by the cell membrane demonstrated that the oleoresin and hardwiickic acid damaged the bacterial membrane irreversibly, which affected membrane integrity. Therefore, the C. pubiflora oleoresin and ent-hardwickiic acid have potential antibacterial effect and can be used as new therapeutic alternatives to treat oral diseases such as dental caries and endodontic infections.

Frequency of Porphyromonas gingivalis fimA in smokers and nonsmokers after periodontal therapy

Porphyromonas gingivalis is one of the most important Gram-negative anaerobe bacteria involved in the pathogenesis of periodontitis. P. gingivalis has an arsenal of specialized virulence factors that contribute to its pathogenicity. Among them, fimbriae play a role in the initial attachment and organization of biofilms. Different genotypes of fimA have been related to length of fimbriae and pathogenicity of the bacterium.

The subgingival periodontal microbiota of the aging mouth

Different mechanisms have been hypothesized to explain the increase in prevalence and severity of periodontitis in older adults, including shifts in the periodontal microbiota. However, the actual impact of aging on the composition of subgingival biofilms remains unclear. In the present article, we provide an overview of the composition of the subgingival biofilm in older adults and the potential effects of age on the oral microbiome. In particular, this review covers the following topics: (i) the oral microbiota of an aging mouth; (ii) the effects of age and time on the human oral microbiome; (iii) the potential impact of inflammaging and immunosenescence in the host-oral microbiota interactions; and (iv) the relationship of the aging oral microbiota and Alzheimer's disease. Finally, we present analyses of data compiled from large clinical studies that evaluated the subgingival microbiota of periodontally healthy subjects and patients with periodontitis from a wide age spectrum (20-83 years of age).

Quantification by qPCR of Pathobionts in Chronic Periodontitis: Development of Predictive Models of Disease Severity at Site-Specific Level

Currently, there is little evidence available on the development of predictive models for the diagnosis or prognosis of chronic periodontitis based on the qPCR quantification of subgingival pathobionts. Our objectives were to: (1) analyze and internally validate pathobiont-based models that could be used to distinguish different periodontal conditions at site-specific level within the same patient with chronic periodontitis; (2) develop nomograms derived from predictive models. Subgingival plaque samples were obtained from control and periodontal sites (probing pocket depth and clinical attachment loss <4 mm and >4 mm, respectively) from 40 patients with moderate-severe generalized chronic periodontitis. The samples were analyzed by qPCR using TaqMan probes and specific primers to determine the concentrations of Actinobacillus actinomycetemcomitans (Aa), Fusobacterium nucleatum (Fn), Parvimonas micra (Pm), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tannerella forsythia (Tf), and Treponema denticola (Td). The pathobiont-based models were obtained using multivariate binary logistic regression. The best models were selected according to specified criteria. The discrimination was assessed using receiver operating characteristic curves and numerous classification measures were thus obtained. The nomograms were built based on the best predictive models. Eight bacterial cluster-based models showed an area under the curve (AUC) ≥0.760 and a sensitivity and specificity ≥75.0%. The PiTfFn cluster showed an AUC of 0.773 (sensitivity and specificity = 75.0%). When Pm and AaPm were incorporated in the TdPiTfFn cluster, we detected the two best predictive models with an AUC of 0.788 and 0.789, respectively (sensitivity and specificity = 77.5%). The TdPiTfAa cluster had an AUC of 0.785 (sensitivity and specificity = 75.0%). When Pm was incorporated in this cluster, a new predictive model appeared with better AUC and specificity values (0.787 and 80.0%, respectively). Distinct clusters formed by species with different etiopathogenic role (belonging to different Socransky’s complexes) had a good predictive accuracy for distinguishing a site with periodontal destruction in a periodontal patient. The predictive clusters with the lowest number of bacteria were PiTfFn and TdPiTfAa, while TdPiTfAaFnPm had the highest number. In all the developed nomograms, high concentrations of these clusters were associated with an increased probability of having a periodontal site in a patient with chronic periodontitis.

Effect of ultrasonic activation on the reduction of bacteria and endotoxins in root canals: a randomized clinical trial

AIM

This randomized clinical trial aimed to compare the effectiveness of ultrasonic activation with that of nonactivated irrigation on the removal of bacteria and endotoxin from root canals.

METHODOLOGY

Fifty patients with necrotic pulps and asymptomatic apical periodontitis were randomly allocated into two groups according to the final irrigation protocol after root canal preparation: Group UI - ultrasonic irrigation (n = 25) and Group NI - needle irrigation (n = 25). The root canals were medicated with calcium hydroxide for 14 days. Microbiological sampling was performed before (S1) and after the root canal preparation (S2), after the irrigation protocols (S3) and after the removal of the intracanal medication (S4). Total bacteria counts were determined by qPCR and the endotoxin levels by the limulus amebocyte lysate assay. Intragroup analyses were performed using the Wilcoxon test for related samples, whereas intergroup analyses were performed using the Mann-Whitney U-test (P < 0.05).

RESULTS

All S1 samples were positive for bacteria, with median numbers of 1.49 × 10⁶ and 8.55 × 10⁵ bacterial cells for the UI and NI groups, respectively. This number significantly decreased in S2 samples (UI: 1.41 × 10⁴ ; NI: 3.53 × 10⁴ ; both with P < 0.001). After final irrigation protocols, there was a significant decrease in bacterial load from S2 to S3 samples in both groups (UI: 4.29 × 10³ ; NI: 1.08 × 10⁴ ; P < 0.01). Intergroup analysis revealed a significant difference between irrigation methods regarding bacterial counts in S3 samples (P < 0.05). In contrast, no significant differences were observed between groups for endotoxin levels (P > 0.05).

CONCLUSIONS

Ultrasonic activation was more effective than nonactivated irrigation for reducing the number of bacteria but not the endotoxin levels in root canals of teeth with apical periodontitis.

Systemic antibiotics in the treatment of periodontitis

Despite the fact that several clinical studies have shown additional benefits when certain systemic antibiotics are used as adjuncts to periodontal treatment, clear guidelines for the use of these agents in the clinical practice are not yet available. Basic questions concerning the use of systemic antibiotics to treat periodontitis remain unanswered, such as: which drug(s) should be used; which patients would most benefit from treatment; which are the most effective protocols (i.e. doses and durations); and in which phase of the mechanical therapy should the drug(s) be administered? Although not all of those questions have been directly addressed by controlled randomized clinical trials, recent concepts related to the ecology of periodontal diseases, as well as the major advances in laboratory and clinical research methods that have occurred in the past decade, have significantly broadened our knowledge in this field. This article endeavored to provide a 'state of the art' overview on the use of systemic antibiotics in the treatment of periodontitis, based on the most recent literature on the topic as well as on a compilation of data from studies conducted at the Center of Clinical Trials at Guarulhos University (São Paulo, Brazil) from 2002 to 2012.

Profiling of subgingival plaque biofilm microbiota in adolescents after completion of orthodontic therapy

Background

Fixed orthodontic treatment is the most common method for malocclusion but has the potential risk of periodontal complication with unclear outcomes of whether microbiologic and clinical changes could be reversible in adolescents after orthodontic therapy.

Methods

Twenty adolescents with orthodontic treatment were enrolled in the study as the case group at end of the therapy, while 19 periodontally healthy adolescents were involved in the control group. At baseline (T₀), clinical parameters including gingival index, probing depth and sulcus bleeding index were tested, and subgingival plaque samples were collected from the lower incisors. The counts of A. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythia and total bacteria were determined by real-time PCR. All parameters were reassessed after 1 month (T₁) and 3 months (T₂) in the case group and compared with that of the controls.

Results

At baseline (T₀), clinical parameters (including GI, PD, SBI) of the test sites in the case group were significantly higher than that of the control group (P<0.05 or P<0.01). At 3 months (T₂), no differences were noticed in GI and SBI between two groups. The prevalence and counts of periodontopathogens tend to be normal (P>0.05), while PD and the amount of P.intermedia were still significantly higher compared with that of the control group (P<0.05 or P<0.01).

Conclusion

After removal of appliances, the periodontal changes induced by orthodontic therapy are only partially reversible at 3 months after removal.

Randomized in vivo evaluation of photodynamic antimicrobial chemotherapy on deciduous carious dentin

The aim of this randomized in vivo study was to compare antimicrobial chemotherapies in primary carious dentin. Thirty-two participants ages 5 to 7 years underwent partial caries removal from deep carious dentin lesions in primary molars and were subsequently divided into three groups: control [chlorhexidine and resin-modified glass ionomer cement (RMGIC)], LEDTB [photodynamic antimicrobial chemotherapy (PACT) with light-emitting diode associated with toluidine blue solution and RMGIC], and LMB [PACT with laser associated with methylene blue solution and RMGIC]. The participants were submitted to initial clinical and radiographic examinations. Demographic features and biofilm, gingival, and DMFT/DMFS indexes were evaluated, in addition to clinical and radiographic followups at 6 and 12 months after treatments. Carious dentin was collected before and after each treatment, and the number of Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei, Fusobacterium nucleatum, Atopobium rimae, and total bacteria was established by quantitative polymerase chain reaction. No signs of pain or restoration failure were observed. All therapies were effective in reducing the number of microorganisms, except for S. sobrinus. No statistical differences were observed among the protocols used. All therapies may be considered as effective modern approaches to minimal intervention for the management of deep primary caries treatment.

Long-term evaluation of oral gavage with periodontopathogens or ligature induction of experimental periodontal disease in mice

OBJECTIVE

To evaluate in long-term periods the destruction of periodontal tissues and bacterial colonization induced by oral gavage with periodontopathogens or ligature experimental periodontal disease models.

MATERIAL AND METHODS

Forty-eight C57BL/6 J mice were divided into four groups: group C: negative control; group L: ligature; group G-Pg: oral gavage with Porphyromonas gingivalis; and group G-PgFn: oral gavage with Porphyromonas gingivalis associated with Fusobacterium nucleatum. Mice were infected by oral gavage five times in 2-day intervals. After 45 and 60 days, animals were sacrificed and the immune-inflammatory response in the periodontal tissue was assessed by stereometric analysis. The alveolar bone loss was evaluated by live microcomputed tomography and histometric analysis. qPCR was used to confirm the bacterial colonization in all the groups. Data were analyzed using the Kruskal-Wallis, Wilcoxon, and ANOVA tests, at 5 % of significance level.

RESULTS

Ligature model induced inflammation and bone resorption characterized by increased number of inflammatory cells and decreased number of fibroblasts, followed by advanced alveolar bone loss at 45 and 60 days (p < 0.05). Bacterial colonization in groups G-Pg and G-PgFn was confirmed by qPCR but inflammation and bone resorption were not observed (p < 0.05).

CONCLUSIONS

The ligature model but not the oral gavage models were effective to induce inflammation and bone loss in long-term periods. Pg colonization was observed in all models of experimental periodontal disease induction, independent of tissue alterations. These mice models of periodontitis validates, compliments, and enhances published PD models that utilize ligature or oral gavage and supports the importance of a successful colonization of a susceptible host, a bacterial invasion into vulnerable tissue, and host-bacterial interactions that lead to tissue destruction.

CLINICAL RELEVANCE

The ligature model was an effective approach to induce inflammation and bone loss similar to human periodontitis, but the oral gavage models were not efficient in inducing periodontal inflammation and tissue destruction in the conditions studied. Ligature models can provide a basis for future interventional studies that contribute to the understanding of the disease pathogenesis and the complex host response to microbial challenge.

Periodontal disease and subgingival microbiota as contributors for rheumatoid arthritis pathogenesis: modifiable risk factors?

PURPOSE OF REVIEW

Since the early 1900s, the role of periodontal disease in the pathogenesis of rheumatoid arthritis has been a matter of intense research. The last decade has witnessed many advances supporting a link between periodontitis, the presence of specific bacterial species (i.e. Porphyromonas gingivalis) and their effects in immune response. This review will examine available evidence on the individuals.

RECENT FINDINGS

Epidemiological studies have stressed the commonalities shared by periodontal disease and rheumatoid arthritis. Many groups have focused their attention toward understanding the periodontal microbiota and its alterations in states of health and disease. The presence of circulating antibodies against periodontopathic bacteria and associated inflammatory response has been found in both rheumatoid arthritis (RA) patients and individuals at-risk for disease development. Most recently, the periodontal microbiota of smokers and patients with RA has been elucidated, revealing profound changes in the bacterial communities compared with those of healthy controls. This has led to several small clinical trials of progressive disease treatment as adjuvant for disease-modifying therapy in RA.

SUMMARY

Smoking and periodontal disease are emerging risk factors for the development of RA. Epidemiological, clinical, and basic research has further strengthened this association, pointing toward changes in the oral microbiota as possible contributors to systemic inflammation and arthritis.

Effect of gallium aluminium arsenide diode laser therapy on Porphyromonas gingivalis in chronic periodontitis: a randomized controlled trial

OBJECTIVES

The aim of this randomized, controlled trial was to evaluate the effects of 685-nm gallium aluminium arsenide (GaAlAs) diode laser therapy (1.6 J cm^-2 ) as an adjunct to scaling and root planing in the treatment of chronic periodontitis.

METHODS

Thirty-two patients aged 35-60 years old who had chronic periodontitis met the eligibility criteria. They were randomly assigned to two equal groups: scaling and root planing were performed in the SRP group, while scaling, root planing and laser irradiation of periodontal pockets were performed in the SRP + DL group. Subgingival plaque samples were subjected to polymerase chain reaction (PCR) to detect P. gingivalis-colonized sites, and common clinical indices were evaluated before and 2 months after treatment. Clinical examination included gingival index (GI), plaque index (PI), probing depth (PD), clinical attachment level (CAL) and gingival bleeding index (GBI), all of which were recorded.

RESULTS

Data from 30 patients [19 women and 11 men; mean age, 48.4 (5.4) years old] were analysed. There were statistically significant improvements in GI, PD, CAL and GBI for the SRP + DL group compared to SRP group but no significant difference in PI between the groups. Additionally, the percentage of P. gingivalis-positive sites in the SRP + DL group decreased from 80% (12/15) to 20% (3/15) after laser irradiation (P < 0.05). No significant changes were noted in the SRP group.

CONCLUSION

GaAlAs diode laser irradiation of diseased periodontal pockets at 685 nm and 1.6 J cm^-2 seemed to be an effective adjuvant to mechanical instrumentation to treat chronic periodontitis.

Current perspective of the impact of smoking on the progression and treatment of periodontitis

This literature review provides an overview of the current scenario regarding the impact of smoking on the progression and treatment of periodontitis; clinical, microbiological and immunological data from studies from our and other groups are presented. In general, preclinical and clinical data are unanimous in demonstrating that smokers present increased susceptibility, greater severity and faster progression of periodontal disease compared with nonsmokers. The evidence further demonstrates that smokers lose more teeth and have a less favorable response to therapy than do nonsmokers. Although it is well established that smoking significantly impacts on the onset, progression and outcome of periodontal disease, the mechanisms involved remain unclear. More importantly, some of the reported deleterious effects of smoking on periodontal tissues have been reported to be reversible upon participation in smoking-cessation programs. Therefore, clinicians should strongly advise smokers to enroll in cessation strategies, even temporarily, in order to improve the overall outcome.

Lineage variability in surface components expression within Porphyromonas gingivalis

The periodontopathogen Porphyromonas gingivalis is represented by a spectrum of phenotypes ranging from commensals to pathogenic lineages. Capsule and fimbriae are considered key virulence factors in this specie, involved in colonization and host defenses evasion. Since these virulence traits may not be expressed by certain strains, we aimed to test the hypothesis that certain clusters or genotypes of P. gingivalis correlate with the production of capsule and fimbriae. Sixteen P. gingivalis isolates were evaluated. Capsule (K) was detected by optical microscopy of negatively stained cells. The presence of fimbriae (F) was determined by TEM. Genotypes were determined by NotI macrorestriction fragments analysis through Pulsed-Field Gel Electrophoresis (PFGE) and Multi-locus sequence typing (MLST) based on seven house-keeping genes. The phenotypes included F(+)K(+) (n = 4), F(-)K(+) (n = 5), F(+)K(-) (n = 5) and F(-)K(-) (n = 2). The analysis of whole genome macrorestriction fragments revealed 14 different clusters. MLST data also revealed extensive genetic diversity; however, PFGE and MLST profiles showed evident differences. There was no association between P. gingivalis clusters and encapsulated and/or fimbriated phenotypes. Genotyping methods were not able to discriminate isolates according to the production of virulence factors such as capsule and major fimbriae, indicating that recombination played a key role in the expression of capsule and fimbriae in P. gingivalis.

Genetic exchange of fimbrial alleles exemplifies the adaptive virulence strategy of Porphyromonas gingivalis

Porphyromonas gingivalis is a gram–negative anaerobic bacterium, a member of the human oral microbiome, and a proposed “keystone” pathogen in the development of chronic periodontitis, an inflammatory disease of the gingiva. P. gingivalis is a genetically diverse species, and is able to exchange chromosomal DNA between strains by natural competence and conjugation. In this study, we investigate the role of horizontal DNA transfer as an adaptive process to modify behavior, using the major fimbriae as our model system, due to their critical role in mediating interactions with the host environment. We show that P. gingivalis is able to exchange fimbrial allele types I and IV into four distinct strain backgrounds via natural competence. In all recombinants, we detected a complete exchange of the entire fimA allele, and the rate of exchange varies between the different strain backgrounds. In addition, gene exchange within other regions of the fimbrial genetic locus was identified. To measure the biological implications of these allele swaps we compared three genotypes of fimA in an isogenic background, strain ATCC 33277. We demonstrate that exchange of fimbrial allele type results in profound phenotypic changes, including the quantity of fimbriae elaborated, membrane blebbing, auto-aggregation and other virulence-associated phenotypes. Replacement of the type I allele with either the type III or IV allele resulted in increased invasion of gingival fibroblast cells relative to the isogenic parent strain. While genetic variability is known to impact host-microbiome interactions, this is the first study to quantitatively assess the adaptive effect of exchanging genes within the pan genome cloud. This is significant as it presents a potential mechanism by which opportunistic pathogens may acquire the traits necessary to modify host-microbial interactions.

Pathogen levels and clinical response to periodontal treatment in patients with Interleukin 8 haplotypes

The aim of this study was to investigate the effect of non-surgical treatment of periodontitis on the levels of periodontopathogens and clinical parameters in patients with different genetic backgrounds produced by polymorphisms in the Interleukin ( IL8) gene. Thirty patients grouped according to IL8 ATC/TTC or AGT/TTC haplotypes were submitted to non-surgical periodontal treatment. Levels of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola were determined in 240 subgingival plaque samples by qPCR. The association between IL8 haplotypes and the levels of periodontopathogens and clinical parameters was investigated by multilevel analysis accounting for the clustering of diseased sites analyzed within patients. It was observed that neither levels of periodontopathogens nor non-surgical treatment was associated with the IL8 haplotype. The clinical parameters after periodontal treatment were similar in diseased and healthy sites, independently of the IL8 haplotype. Nonetheless, in the same period, diseased sites of AGT/TTC patients harbored higher levels of P. gingivalis, T. denticola, T. forsythia, and red complex than those of ATC/TTC patients. However, the non-surgical periodontal therapy decreased the levels of these periodontopathogens and of the tested clinical parameters of diseased sites in both groups. Non-surgical therapy is equally effective in improving clinical parameters and decreasing the levels of periodontopathogens, independent of the genotype groups produced by the IL8 haplotype.

Periodontopathogens levels and clinical response to periodontal therapy in individuals with the interleukin-4 haplotype associated with susceptibility to chronic periodontitis

Periodontitis is an inflammatory disease that results from an interaction between dental biofilm agents and the host immune-inflammatory response. Periodontopathogenic organisms, such as Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola, as well as the host's susceptibility, represented by the host's genetic makeup, are the key factors that influence this complex disease. Recently, we identified haplotypes in the IL4 gene that were associated with chronic periodontitis (CP). This study aimed to evaluate whether subjects with different IL4 haplotypes (TCI/CCI and TTD/CTI) would be differentially colonized by periodontopathogens and whether they would respond differently to non-surgical periodontal therapy. Thirty-nine patients carrying the IL4 haplotype of genetic susceptibility to CP (IL4+) or protection against CP (IL4-) were evaluated. Those groups were further subdivided into individuals with CP (CP IL4+ or CP IL4-) and those that were periodontally healthy (H) (H IL4+ or H IL4-). CP patients were submitted to non-surgical periodontal therapy. Clinical and microbiological analyses were performed considering the data at baseline and 45 and 90 days after periodontal therapy. Periodontopathogens levels were evaluated by absolute quantitative polymerase chain reaction (qPCR). The baseline data revealed that the total levels of periodontopathogens were higher in the CP IL4+ than in the CP IL4- groups. Clinical analyses revealed that the periodontal therapy was equally effective, independent of the subject's IL4 genetic load. The TCI/CCI IL4 haplotype, previously associated with genetic susceptibility to CP, was also associated with increased levels of periodontopathogenic bacteria, but this genetic background did not influence the response to non-surgical periodontal treatment.

Association between IL8 haplotypes and pathogen levels in chronic periodontitis

Chronic periodontitis (CP) is considered to be a multifactorial disease influenced by microbial and genetic factors. The aim of the present study was to investigate whether the genetic susceptibility to CP in individuals with the IL8 ATC/TTC haplotype is associated with subgingival levels of periodontopathogens. Sixty-five individuals, grouped according to the presence (n = 28) or absence (n = 37) of the IL8 haplotype, were evaluated. After clinical periodontal evaluation, each group was subdivided according to the presence (CP) or absence (H) of periodontitis. Four subgingival samples were obtained from CP and two samples per subject from H patients. The levels and proportions of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola were analyzed using quantitative real-time polymerase chain reaction (q-PCR). No differences were found in the proportion of periodontopathogenic bacteria between groups with the presence or absence of the IL8 haplotype. However, in the CP groups, the levels of periodontopathogens were significantly higher in the individuals without the IL8 haplotype than in the individuals with the IL8 haplotype. These results suggest that periodontal destruction may occur in patients who are considered to be genetically susceptible to CP with a lower microbial challenge because of the presence of the IL8 ATC/TTC haplotype than in patients without this haplotype.

Smoking and periodontal tissues: a review

The impact of smoking on general health has been widely studied and is directly related to several important medical problems including cancer, low birth weight, and pulmonary and cardiovascular disease. In the past 25 years, there has also been an increasing awareness of the role of cigarette consumption in oral health problems such as periodontal disease. Smoking is considered the major risk factor in the prevalence, extent and severity of periodontal diseases. This article will discuss the available evidence and provide the reader with an overview of the impact of smoking and its cessation on the pathogenesis and treatment of periodontal diseases.

The sociodemographic characteristics, periodontal health status, and subgingival microbiota of patients with chronic periodontitis and type 2 diabetes mellitus: a case-control study in a Chinese population

BACKGROUND

In China, chronic periodontitis (CP) is common in patients with type 2 diabetes mellitus (T2DM). The purpose of this study is to identify the sociodemographic characteristics associated with such patients and to assess the periodontal health status and subgingival microbiota of patients with CP and T2DM (T2DMCP) in the Chinese population.

METHODS

A total of 150 patients with T2DMCP and 306 patients with CP without any systemic disease completed questionnaires, underwent clinical periodontal examinations and participated in diabetes-related parameter examinations. Subgingival plaques were obtained to determine the prevalence and amounts of selected oral bacterial species using polymerase chain reaction (PCR) and real-time PCR, respectively.

RESULTS

The income level and mean body mass index (BMI) of the patients with T2DMCP were significantly higher than those of the patients with CP. Additionally, the patients with T2DMCP were more likely to be urban residents, and they had significantly more severe periodontitis than did the patients with CP. In the patients with T2DMCP, the prevalence and amounts of Treponema denticola and Tannerella forsythia were significantly higher than those in the patients with CP. Finally, compared with the patients with CP, the patients with T2DMCP had a significantly lower prevalence and amount of Prevotella intermedia.

CONCLUSIONS

Compared with the patients with CP, the patients with T2DMCP were more likely to be urban residents and generally had higher incomes, higher mean BMI, and poorer periodontal health status. Higher levels of T. denticola and T. forsythia and lower levels of P. intermedia were identified in the subgingival plaque of the patients with T2DMCP.

Porphyromonas endodontalis in chronic periodontitis: a clinical and microbiological cross-sectional study

Background

Although previous studies have shown the presence of Porphyromonas endodontalis in chronic periodontitis associated with periapical lesions, the occurrence of this pathogen in diseased periodontal sites without periapical lesions has been poorly investigated.

Objective

The aims of this study were to quantify P. endodontalis in patients with chronic periodontitis without periapical lesions, to evaluate the potential correlation of P. endodontalis with Porphyromonas gingivalis and Tannerella forsythia, and to evaluate the ability of periodontal treatment to reduce these pathogens.

Design

Patients with generalized chronic periodontitis were selected by recording clinical attachment level (CAL), probing depth (PD), and bleeding on probing (BOP). Subgingival samples from 30 diseased nonadjacent sites (CAL≥5 mm, PD between 5 and 7 mm and positive BOP) and 30 healthy nonadjacent sites (PD≤3 mm and negative BOP) were collected and subjected to microbial analysis by quantitative polymerase chain reaction (qPCR) The variables of age, PD, CAL and BOP of all individuals were analyzed using the paired t-test (GrapPad Prism5^®). Data of bacteria quantification were subjected to a normality test (D'Agostino-Pearson Test). For bacterial correlation analysis, the Spearman correlation was used.

Results

Our results showed that diseased sites had significantly higher levels of P. endodontalis compared to healthy sites, similar to the results obtained for P. gingivalis and T. forsythia. The numbers of all bacterial species were reduced significantly after mechanical periodontal treatment. P. endodontalis was significantly correlated with the presence of T. forsythia and P. gingivalis in the diseased group.

Conclusion

Our results suggest that there is a high prevalence of P. endodontalis, P. gingivalis and T. forsythia in periodontitis sites and that mechanical periodontal treatment is effective at reducing the pathogens studied.

Differential expression and adherence of Porphyromonas gingivalis FimA genotypes

Porphyromonas gingivalis is a primary pathogen involved in the initiation and progression of adult chronic periodontitis. Its colonization on oral surfaces is a necessary first step leading to infection. FimA, a subunit protein of major (long) fimbriae, is a well-known virulence factor. Based on its nucleotide sequence, FimA is classified into several genotypes. We compared here the transcriptional levels of the fimA gene in several P. gingivalis strains using real-time polymerase chain reaction analysis, fimbrial display on the P. gingivalis surface using transmission electronic microscopy, and the adherence competencies of P. gingivalis strains carrying different types of FimAs towards saliva and Streptococcus gordonii surfaces using mutagenesis analysis. We demonstrated differential expression of each fimA gene in these P. gingivalis strains. A correlation of the transcription level of fimA and binding activity of P. gingivalis was revealed. We show that P. gingivalis strains with genotype I and II of FimA are efficient in interaction with saliva or S. gordonii. This work highlights the important role of FimA type I and II in P. gingivalis attachment to oral surfaces.

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.