What exactly distinguishes aggressive from chronic periodontitis: is it mainly a difference in the degree of bacterial invasiveness?

Effect of 5-aminolevulinic acid-mediated photodynamic therapy against Fusobacterium nucleatum in periodontitis prevention

Periodontitis, a chronic infectious disease leading to gingival atrophy and potential tooth loss through alveolar bone resorption, is closely linked to the oral microbiome. Fusobacterium nucleatum, known to facilitate late-stage bacterial colonization in the oral microbiome, plays a crucial role in the onset of periodontitis. Controlling F. nucleatum abundance is vital for preventing and treating periodontal disease. Photodynamic therapy combined with 5-aminolevulinic acid (ALA-PDT) has been reported to be bactericidal against Pseudomonas aeruginosa and Staphylococcus aureus. We aimed to investigate the bactericidal potential of ALA-PDT against F. nucleatum, which was evaluated by examining the impact of varying 5-ALA concentrations, culture time, and light intensity. After ALA-PDT treatment, DNA was extracted from interdental plaque samples collected from 10 volunteers and sequenced using the Illumina MiSeq platform. To further elucidate the bactericidal mechanism of ALA-PDT, porphyrins were extracted from F. nucleatum following cultivation with 5-ALA and subsequently analyzed using fluorescence spectra. ALA-PDT showed a significant bactericidal effect against F. nucleatum. Its bactericidal activity demonstrated a positive correlation with culture time and light intensity. Microbiota analysis revealed no significant alteration in α-diversity within the ALA-PDT group, although there was a noteworthy reduction in the proportion of the genus Fusobacterium. Furthermore, fluorescence spectral analysis indicated that F. nucleatum produced an excitable photosensitive substance following the addition of 5-ALA. Overall, if further studies confirm these results, this combined therapy could be an effective strategy for reducing the prevalence of periodontitis.

Elevated subgingival temperature infers high bacterial pathogen counts in severe periodontitis

OBJECTIVES

Periodontal inflammation may be assessed by bleeding on probing and subgingival temperature. This pilot study evaluated the intrapatient relationship between subgingival temperature and selected bacterial groups/species in deep periodontal pockets with bleeding on probing.

MATERIALS AND METHODS

In each of eight adults, an electronic temperature probe identified three "hot" pockets with elevated subgingival temperature and three "cool" pockets with normal subgingival temperature among premolars/molars with 6‒10 mm probing depths and bleeding on probing. Microbial samples collected separately from the hot and cool periodontal pockets were cultured for selected periodontal pathogens.

RESULTS

Hot compared to cool periodontal pockets revealed significantly higher absolute and normalized subgingival temperatures and yielded higher mean proportions of Porphyromonas gingivalis (10.2% for hot vs. 2.5% for cool, p = 0.030) and total red/orange complex periodontal pathogens (48.0% for hot vs. 24.6% for cool, p = 0.012).

CONCLUSIONS

Hot versus cool deep periodontal pockets harbored significantly higher levels of major periodontal pathogens. Subgingival temperature measurements may potentially be useful to assess risk of periodontitis progression and the efficacy of periodontal therapy.

Increased dental comorbidities in patients with psoriasis: a nationwide population-based cohort study in Korea

BACKGROUND

Limited data are available regarding the association between psoriasis and common dental conditions.

OBJECTIVES

To investigate the risk of potential dental comorbidities in patients with psoriasis.

METHODS

We conducted a nationwide population-based cohort study to analyse the claims data of patients with psoriasis (n = 15 165) and age- and sex-matched controls (n = 75 825). The incidence risk of the following potential dental conditions was analysed: dental caries, pulp and periapical disease, periodontal disease, gingival changes and tooth loss.

RESULTS

After adjusting for potential cofactors, the adjusted hazard ratios (aHRs) of dental caries [1.105; 95% confidence interval (CI) 1.078-1.132], pulp and periapical disease (1.07; 95% CI 1.044-1.096) and periodontal disease (1.108; 95% CI 1.088-1.129) were significantly higher than those in the control cohort (P < 0.001). However, among the subset of patients with psoriasis who received systemic antipsoriatic treatment (n = 4275), the aHR risk of all potential dental comorbidities was not significantly higher from that of the control cohort.

CONCLUSIONS

Patients with psoriasis have an increased risk of dental comorbidities, and systemic antipsoriatic treatment may help mitigate this increased risk.

Persister Cell Formation and Elevated lsrA and lsrC Gene Expression upon Hydrogen Peroxide Exposure in a Periodontal Pathogen Aggregatibacter actinomycetemcomitans

The effect of hydrogen peroxide, an antiseptic dental treatment, on Aggregatibacter actinomycetemcomitans, the main causative agent of localized invasive periodontitis, was investigated. Hydrogen peroxide treatment (0.06%, 4× minimum inhibitory concentration) resulted in the persistence and survival of approximately 0.5% of the bacterial population. The surviving bacteria did not genetically acquire hydrogen peroxide resistance but exhibited a known persister behavior. Sterilization with mitomycin C significantly reduced the number of A. actinomycetemcomitans persister survivors. RNA sequencing of hydrogen peroxide-treated A. actinomycetemcomitans showed elevated expression of Lsr family members, suggesting a strong involvement of autoinducer uptake. In this study, we found a risk of A. actinomycetemcomitans persister residual from hydrogen peroxide treatment and hypothesized associated genetic mechanisms of persister from RNA sequencing.

Role of ubiquitin-specific protease 5 in the inflammatory response of chronic periodontitis

BACKGROUND

The systemic inflammatory response caused by chronic periodontitis is a risk factor for multiple diseases. Ubiquitin-specific protease 5 (USP5) is a kind of deubiquitinase which mainly responsible for dissociating unanchored polyubiquitin. However, the functions of USP5 in chronic periodontitis have not been reported.

METHODS

Chronic periodontitis patients were recruited, and their periodontal samples were collected. The levels of USP5, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in gingival crevicular fluid were evaluated by ELISA. The expression of USP5, TNF-α, IL-6, and IL-1β in human periodontal ligament stem cells (PDLSCs) was estimated by qRT-PCR assay. The activation of STAT3 signaling was examined by Western blot.

RESULTS

USP5 was upregulated in the gingival crevicular fluid and gingival tissues of chronic periodontitis patients. USP5 expression was positively correlated with the expression of proinflammatory factors. USP5 knockdown and deubiquitinase inhibitor inhibited LPS-induced inflammatory responses in PDLSCs. Suppressing USP5 inhibited STAT3 signaling in PDLSCs.

CONCLUSION

Suppression deubiquitinase USP5 inhibits the inflammatory response of chronic periodontitis by suppressing STAT3 signaling.

The effect of the "Oral-Gut" axis on periodontitis in inflammatory bowel disease: A review of microbe and immune mechanism associations

Periodontitis and inflammatory bowel diseases (IBD) are inflammatory diseases of the gastrointestinal tract that share common features of microbial-induced ecological dysregulation and host immune inflammatory response. The close relationship between periodontitis and IBD is characterized by a higher prevalence of IBD in patients with periodontitis and a higher prevalence and severity of periodontitis in patients with IBD, indicating that periodontitis and IBD are different from the traditional independent diseases and form an "Oral-Gut" axis between the two, which affect each other and thus form a vicious circle. However, the specific mechanisms leading to the association between the two are not fully understood. In this article, we describe the interconnection between periodontitis and IBD in terms of microbial pathogenesis and immune dysregulation, including the ectopic colonization of the gut by pathogenic bacteria associated with periodontitis that promotes inflammation in the gut by activating the host immune response, and the alteration of the oral microbiota due to IBD that affects the periodontal inflammatory response. Among the microbial factors, pathogenic bacteria such as Klebsiella, Porphyromonas gingivalis and Fusobacterium nucleatum may act as the microbial bridge between periodontitis and IBD, while among the immune mechanisms, Th17 cell responses and the secreted pro-inflammatory factors IL-1β, IL-6 and TNF-α play a key role in the development of both diseases. This suggests that in future studies, we can look for targets in the "Oral-Gut" axis to control and intervene in periodontal inflammation by regulating periodontal or intestinal flora through immunological methods.

Porphyromonas gingivalis Virulence Factors and Clinical Significance in Periodontal Disease and Coronary Artery Diseases

Porphyromonas gingivalis is a gram-negative, anaerobic bacterium that lives in the oral cavity. It is an integral part of the oral microbiome, which includes more than 500 types of bacteria. Under certain circumstances, as a consequence of virulence factors, it can become very destructive and proliferate to many cells in periodontal lesions. It is one of the causative agents present extremely often in dental plaque and is the main etiological factor in the development of periodontal disease. During various therapeutic procedures, P. gingivalis can enter the blood and disseminate through it to distant organs. This primarily refers to the influence of periodontal agents on the development of subacute endocarditis and can facilitate the development of coronary heart disease, atherosclerosis, and ischemic infarction. The action of P. gingivalis is facilitated by numerous factors of virulence and pathogenicity such as fimbriae, hemolysin, hemagglutinin, capsules, outer membrane vesicles, lipopolysaccharides, and gingipains. A special problem is the possibility of biofilm formation. P. gingivalis in a biofilm is 500 to 1000 times less sensitive to antimicrobial drugs than planktonic cells, which represents a significant problem in the treatment of infections caused by this pathogen.

Evaluation of the Effect of Non-Surgical Periodontal Treatment on Oral Health-Related Quality of Life in Patients with Periodontitis at Different Stages

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Gallic Acid Ameliorates the Inflammatory State of Periodontal Ligament Stem Cells and Promotes Pro-Osteodifferentiation Capabilities of Inflammatory Stem Cell-Derived Exosomes

The slow proliferation rate and poor osteodifferentiation ability of inflammatory periodontal membrane stem cells extracted from periodontitis tissues (i-PDLSCs) account for poor efficiency in treating inflammatory bone loss. Exosomes reportedly have inducible and relatively stable components, allowing them to promote inflammatory bone repair, but obtaining i-PDLSCs exosomes with the ability to promote osteodifferentiation is challenging. In the present study, i-PDLSCs were extracted from periodontal membrane tissues of patients with severe periodontitis, and in vitro induction with gallic acid (GA) significantly promoted the proliferative activity of i-PDLSCs at a concentration of 10 mM, with TC₀ of 11.057 mM and TC₅₀ of 67.56 mM for i-PDLSCs. After mRNA sequencing, we found that GA could alleviate oxidative stress in i-PDLSCs and increase its mitochondrial membrane potential and glucose aerobic metabolism level, thus promoting the osteodifferentiation of i-PDLSCs. After exosomes of i-PDLSCs after GA induction (i-EXO-GA) were isolated by differential centrifugation, we found that 200 ug/mL of i-EXO-GA could remarkably promote the osteodifferentiation of i-PDLSCs. Overall, our results suggest that GA induction can enhance the proliferation and osteodifferentiation in primary cultures of i-PDLSCs in vitro, mediated by alleviating oxidative stress and glycometabolism levels in cells, which further influences the osteodifferentiation-promoting ability of i-EXO-GA. Overall, we provide a viable cell and exosome induction culture method for treating inflammatory alveolar defects associated with periodontitis.

Periodontitis and cardiometabolic disorders: The role of lipopolysaccharide and endotoxemia

Lipopolysaccharide is a virulence factor of gram-negative bacteria with a crucial importance to the bacterial surface integrity. From the host's perspective, lipopolysaccharide plays a role in both local and systemic inflammation, activates both innate and adaptive immunity, and can trigger inflammation either directly (as a microbe-associated molecular pattern) or indirectly (by inducing the generation of nonmicrobial, danger-associated molecular patterns). Translocation of lipopolysaccharide into the circulation causes endotoxemia, which is typically measured as the biological activity of lipopolysaccharide to induce coagulation of an aqueous extract of blood cells of the assay. Apparently healthy subjects have a low circulating lipopolysaccharide activity, since it is neutralized and cleared rapidly. However, chronic endotoxemia is involved in the pathogenesis of many inflammation-driven conditions, especially cardiometabolic disorders. These include atherosclerotic cardiovascular diseases, obesity, liver diseases, diabetes, and metabolic syndrome, where endotoxemia has been recognized as a risk factor. The main source of endotoxemia is thought to be the gut microbiota. However, the oral dysbiosis in periodontitis, which is typically enriched with gram-negative bacterial species, may also contribute to endotoxemia. As endotoxemia is associated with an increased risk of cardiometabolic disorders, lipopolysaccharide could be considered as a molecular link between periodontal microbiota and cardiometabolic diseases.

Complement component 3 (C3) and its activation split-products in saliva associates with periodontitis

BACKGROUND AND OBJECTIVE

Periodontitis (PD) is classified by grades A through C according to the risk of further progression, PD grade C (PD-C) being the most severe progressing form. It is a matter of controversy, whether the disease activity observed in PD-C is due to impaired immune reactivity towards bacteria embedded in biofilms or a hyper-reactive immune response causing tissue damage as a bystander phenomenon. Little is known about the role of complement in this respect.

MATERIALS AND METHODS

Plasma and unstimulated saliva samples were collected from patients with PD-B (n = 34) or -C (n = 27) and healthy controls (HCs) (n = 28). Salivary and plasma levels of total C3, C3c and C3dg were quantified using sandwich ELISA.

RESULTS

Salivary levels of total C3 and C3dg were elevated in PD-B and PD-C patients compared to HCs (both p< 0.05), while the levels of C3c were elevated in PD-C compared to HCs. Plasma levels of C3c were higher in PD-B patients than in HCs (p< 0.05).

CONCLUSION

PD-B and PD-C patients show increased complement activation compared to HCs, but no difference was found between the two disease grades. PD-B, but not PD-C, is associated with increased systemic complement activation as assessed by C3c in plasma. This article is protected by copyright. All rights reserved.

Adjunctive Application of Systemic Antibiotics in Non-surgical Aggressive Periodontitis Treatment: Clinical and Microbiological Findings

BACKGROUND: Aggressive periodontitis (AgP) is associated with an extensive and rapid destruction of periodontal tissues. Unpredictable treatment outcomes of the disease are consequences of various cross-linked factors. Antimicrobial adjunctive treatment is routinely used as a part of non-surgical periodontal treatment (NSPT) of AgP. AIM: Therefore, the aim of this study was to compare the effects of active periodontal treatment (APT) combined with systemic antibiotics with mechanical debridement alone, in patients with generalized AgP (GAgP). METHODS: Two groups, consisting of 10 participants each, were randomly formed. Both groups were clinically and microbiologically tested and monitored for 3 months. Test group received APT with antimicrobial supplementation (amoxicillin and metronidazole [AMX-MET]). Patients from the control group were treated by APT only. Clinical and microbiological parameters were recorded at baseline and 3 months following the NSPT. Clinical measurements involved probing depth, clinical attachment level, bleeding on probing, and plaque index. Samples of subgingival crevicular fluid were analyzed by qualitative polymerase chain reaction. RESULTS: Significant improvement of all clinical parameters was observed 3 months following the NSPT (p < 0.05), but significant difference between groups was not found (p > 0.05). Periodontal pathogens’ detection between baseline and 3 months follow-up was also not statistically significant in both examined groups (p > 0.05). CONCLUSION: Similarity of results obtained in both treatment groups underlined the key role of APT in the treatment of AgP. The AMX-MET supplementation did not improve clinical and microbiological outcomes, when compared to APT alone. Longer follow-up period, with larger sample, could provide a more comprehensive insight into this issue.

Effectiveness of Antimicrobial Photodynamic Therapy in the Treatment of Periodontitis: A Systematic Review and Meta-Analysis of In Vivo Human Randomized Controlled Clinical Trials

This systematic review and meta-analysis evaluated antimicrobial photodynamic therapy (aPDT) efficacy in periodontitis. The review protocol was conducted in accordance with PRISMA statements, Cochrane Collaboration recommendations and is registered in PROSPERO (CRD 42020161516). Electronic and hand search strategies were undertaken to gather data on in vivo human RCTs followed by qualitative analysis. Differences in probing pocket depth (PPD) and clinical attachment level (CAL) were calculated with 95% confidence intervals and pooled in random effects model at three and six months. Heterogeneity was analyzed, using Q and I² tests. Publication bias was assessed by visual examination of the funnel plot symmetry. Sixty percent of 31 eligible studies showed a high risk of bias. Meta-analysis on 18 studies showed no additional benefit in split mouth studies in terms of PPD reduction (SMD 0.166; 95% CI −0.278 to 0.611; P = 0.463) and CAL gain (SMD 0.092; 95% CI −0.013 to 0.198; P = 0.088). Similar findings noted for parallel group studies; PPD reduction (SMD 0.076; 95% CI −0.420 to 0.573; P = 0.763) and CAL gain (SMD 0.056; 95% CI −0.408 to 0.552; P = 0.745). Sensitivity analysis minimized heterogeneity for both outcome variables; however, intergroup differences were not statistically significant. Future research should aim for well-designed RCTs in order to determine the effectiveness of aPDT.

Is antimicrobial photodynamic therapy an effective treatment modality for aggressive periodontitis? A systematic review of in vivo human randomized controlled clinical trials

BACKGROUND

Limitations of scaling and root planing (SRP) have directed research to utilize additional therapies to enhance conventional techniques. The present systematic review was conducted to evaluate and present a comprehensive overview on effectiveness of antimicrobial photodynamic therapy (aPDT) in the management of aggressive periodontitis (AgP).

METHODOLOGY

The PRISMA statement guidelines and Cochrane Collaboration recommendations were followed to conduct this systematic review. The review protocol is registered in PROSPERO (CRD 42019143316). A structured electronic and manual search strategy was implied to gather the relevant published data on in vivo human RCTs from their earliest records until 31st October 2019. Relevant data was extracted from the eligible studies, analysed and impartially appraised for its quality.

RESULTS

Eleven papers met the eligibility criteria and included in this review. The data on standardized study protocol, ideal photosensitizer (PS) dye-wavelength combination, optimal parameters was inconclusive and a high risk of bias in majority of the studies noted, which are fundamental in establishing a standardized and replicable protocol.

CONCLUSION

Ultimately researchers should conduct well-designed and robust RCTs performed by trained clinicians in order to determine the effectiveness of aPDT, if any, after acknowledging the drawbacks highlighted in this systematic review.

The Oral Microbiome in Periodontal Health

The estimation of oral microbiome (OM) taxonomic composition in periodontally healthy individuals can often be biased because the clinically periodontally healthy subjects for evaluation can already experience dysbiosis. Usually, they are included just based on the absence of clinical signs of periodontitis. Additionally, the age of subjects is used to be higher to correspond well with tested groups of patients with chronic periodontitis, a disorder typically associated with aging. However, the dysbiosis of the OM precedes the clinical signs of the disease by many months or even years. The absence of periodontal pockets thus does not necessarily mean also good periodontal health and the obtained image of "healthy OM" can be distorted.To overcome this bias, we taxonomically characterized the OM in almost a hundred young students of dentistry with precise oral hygiene and no signs of periodontal disease. We compared the results with the OM composition of older periodontally healthy individuals and also a group of patients with severe periodontitis (aggressive periodontitis according to former classification system). The clustering analysis revealed not only two compact clearly separated clusters corresponding to each state of health, but also a group of samples forming an overlap between both well-pronounced states. Additionally, in the cluster of periodontally healthy samples, few outliers with atypical OM and two major stomatotypes could be distinguished, differing in the prevalence and relative abundance of two main bacterial genera: Streptococcus and Veillonella. We hypothesize that the two stomatotypes could represent the microbial succession from periodontal health to starting dysbiosis. The old and young periodontally healthy subjects do not cluster separately but a trend of the OM in older subjects to periodontitis is visible. Several bacterial genera were identified to be typically more abundant in older periodontally healthy subjects.

Neutrophils exhibit an individual response to different oral bacterial biofilms

Oral innate immunity is led by neutrophils. It is still unclear how their main antimicrobial mechanisms against different biofilms may contribute to balance or dysregulation in the oral cavity. We investigated the capacity of commensal (Streptococcus oralis) and pathogenic (Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans) monospecies biofilms to induce or to inhibit selected antimicrobial mechanisms of neutrophils. S. oralis induced neutrophil extracellular traps (NETs) formation, reactive oxygen species (ROS) production, and matrix metalloproteinases (MMPs) 8 and 9 secretion. However, these responses were partially reduced in PMA-activated neutrophils indicating a balance-like neutrophil response, which might be important for the maintenance of oral health. P. gingivalis generally induced ROS. Reduced NET formation and significantly decreased MMP secretion were detectable in activated neutrophils highlighting P. gingivalis’ nucleolytic and proteolytic activity, which might support bacterial colonization and pathogenesis of periodontitis. In contrast, A. actinomycetemcomitans did not affect the levels of antimicrobial factors in activated neutrophils and induced NET formation, ROS production, and secretion of MMP-8 and -9 in neutrophils alone, which might contribute to tissue destruction and disease progression. In summary, neutrophil responses to biofilms were species-specific and might support either maintenance of oral health or pathogenesis of periodontitis depending on the species.

Effectiveness of antimicrobial photodynamic therapy as an adjunct to open flap debridement in patients with aggressive periodontitis

AIM

The aim of the present clinical trial was to evaluate the clinical efficacy of photodynamic therapy (PDT) as an adjunct to open flap debridement (OFD) in the treatment of generalized aggressive periodontitis (GAP).

MATERIALS AND METHODS

The subjects recruited for the study were divided into two groups: 'control group' received treatment through OFD, whereas the test participants were treated with OFD and adjunctive PDT. The clinical periodontal parameters were plaque index (PI), full mouth probing depth (FMPD) and full mouth relative attachment loss (FMRA). The microbial levels of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Tannarella forsythia (Tf) were analyzed. All parameters were assessed at baseline and 3 months.

STATISTICAL ANALYSIS

The observed values for all the parameters were reported in mean and standard deviation (mean ± SD). In order to analyse the mean values and inter-group comparisons, the Mann-Whitney U test was employed. The p-value was set at <0.05 to establish a significant difference among the reported values.

RESULTS

A statistically significant improvement for BOP was observed in PDT group in comparison to the control group at 3 months only (p < 0.05). A significant reduction in the microbiological levels for Aa, Pg and Tf in both the study groups was observed. However, no significant differences in microbial levels were observed at any time point when the control and test groups were compared to each other.

CONCLUSION

PDT in conjuction with OFD plays a significant role in reducing the microbial load and improving the clinical periodontal parameters in patients with GAP. Moreover, it is regarded as a safe treatment regimen as no side effects have been reported regarding its use in GAP.

Three periodontitis phenotypes: Bone loss patterns, antibiotic-surgical treatment and the new classification

AIM

To compare three periodontitis clusters (A, B and C) for alveolar bone loss (ABL) patterns, antibiotic prescriptions and surgeries and to relate them to the new classification of periodontitis.

MATERIALS AND METHODS

ABL patterns, prescription of systemic antibiotics and the number of surgeries were retrieved for all patients (n = 353) in the clusters. Comparisons and possible predictors for antibiotics were assessed, and results also evaluated in relation to the new classification.

RESULTS

Cluster A is characterized by angular defects often affecting the first molars and localized stage III/IV grade C periodontitis. Cluster B contains mainly localized or generalized stage III/IV, grade C patients. Cluster C contains mainly patients with generalized stage III/IV grade C periodontitis. Patients in cluster A received significantly more antibiotics compared to B and C (78% vs. 23% and 17%); the predictors for antibiotic prescription were young age and localized ABL. No differences in numbers of periodontal surgeries were observed between clusters (A = 1.0 ± 1.4, B = 1.3 ± 1.4 and C = 1.3 ± 1.5).

CONCLUSIONS

Within stage III/IV grade C periodontitis, we could detect three clusters of patients. The distinct localized ABL pattern and younger age in cluster A presumably prompted clinicians to prescribe antibiotics.

Application of weighted gene co-expression network analysis to reveal key modules and hub genes in generalized aggressive periodontitis

OBJECTIVE

The aim of this study was to construct a gene co-expression network to identify key modules and genes in people with generalized aggressive periodontitis.

METHODS

We used database GSE79705 to construct a co-expression network by weighted gene co-expression network analysis (WGCNA). In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted.

RESULTS

A total of 51 co-expression modules were conducted, darkseagreen1 and blue1 modules were the most significantly related to generalized aggressive periodontitis. Genes in the darkseagreen1 module enriched in affecting cellular response to tumor necrosis factor and vascular endothelial growth factor production, and the blue1 module enriched in the regulation of ion transport, proteinaceous extracellular matrix and neuropeptide binding. Besides, we found that 4 hub genes (SNRPG, MRPL22, MRPS18C and CEP290) played an important role in the occurrence of generalized aggressive periodontitis.

CONCLUSION

Through this study, we identified two modules and four hub genes associated with generalized aggressive periodontitis. Besides, 4 hub genes (SNRPG, MRPL22, MRPS18C and CEP290) can be expected to trigger new therapeutic drug development for generalized aggressive periodontitis.

The role of inflammation and genetics in periodontal disease

Periodontitis is a complex disease: (a) various causative factors play a role simultaneously and interact with each other; and (b) the disease is episodic in nature, and bursts of disease activity can be recognized, ie, the disease develops and cycles in a nonlinear fashion. We recognize that various causative factors determine the immune blueprint and, consequently, the immune fitness of a subject. Normally, the host lives in a state of homeostasis or symbiosis with the oral microbiome; however, disturbances in homeostatic balance can occur, because of an aberrant host response (inherited and/or acquired during life). This imbalance results from hyper- or hyporesponsiveness and/or lack of sufficient resolution of inflammation, which in turn is responsible for much of the disease destruction seen in periodontitis. The control of this destruction by anti-inflammatory processes and proresolution processes limits the destruction to the tissues surrounding the teeth. The local inflammatory processes can also become systemic, which in turn affect organs such as the heart. Gingival inflammation also elicits changes in the ecology of the subgingival environment providing optimal conditions for the outgrowth of gram-negative, anaerobic species, which become pathobionts and can propagate periodontal inflammation and can further negatively impact immune fitness. The factors that determine immune fitness are often the same factors that determine the response to the resident biofilm, and are clustered as follows: (a) genetic and epigenetic factors; (b) lifestyle factors, such as smoking, diet, and psychosocial conditions; (c) comorbidities, such as diabetes; and (d) local and dental factors, as well as randomly determined factors (stochasticity). Of critical importance are the pathobionts in a dysbiotic biofilm that drive the viscious cycle. Focusing on genetic factors, currently variants in at least 65 genes have been suggested as being associated with periodontitis based on genome-wide association studies and candidate gene case control studies. These studies have found pleiotropy between periodontitis and cardiovascular diseases. Most of these studies point to potential pathways in the pathogenesis of periodontal disease. Also, most contribute to a small portion of the total risk profile of periodontitis, often limited to specific racial and ethnic groups. To date, 4 genetic loci are shared between atherosclerotic cardiovascular diseases and periodontitis, ie, CDKN2B-AS1(ANRIL), a conserved noncoding element within CAMTA1 upstream of VAMP3, PLG, and a haplotype block at the VAMP8 locus. The shared genes suggest that periodontitis is not causally related to atherosclerotic diseases, but rather both conditions are sequelae of similar (the same?) aberrant inflammatory pathways. In addition to variations in genomic sequences, epigenetic modifications of DNA can affect the genetic blueprint of the host responses. This emerging field will yield new valuable information about susceptibility to periodontitis and subsequent persisting inflammatory reactions in periodontitis. Further studies are required to verify and expand our knowledge base before final cause and effect conclusions about the role of inflammation and genetic factors in periodontitis can be made.

Interleukin Gene Variability and Periodontal Bacteria in Patients with Generalized Aggressive Form of Periodontitis

Host genetic predispositions to dysregulated immune response can influence the development of the aggressive form of periodontitis (AgP) through susceptibility to oral dysbiosis and subsequent host-microbe interaction. This case-control study aimed to perform a multilocus analysis of functional variants in selected interleukin (IL) genes in patients with the generalized form of AgP in a homogenous population. Twelve polymorphisms in IL-1 gene cluster, IL-6 and its receptor, IL-10, IL-17A, and IL-18 were determined in 91 AgP patients and 210 controls. Analysis of seven selected periodontal bacteria in subgingival sulci/pockets was performed with a commercial DNA-microarray kit in a subgroup of 76 individuals. The pilot in vitro study included stimulation of peripheral blood monocytes (PBMC) from 20 individuals with periodontal bacteria and measurement of IL-10 levels using the Luminex method. Only the unctional polymorphism IL-10 −1087 A/G (rs1800896) and specific IL-10 haplotypes were associated with the development of the disease (p < 0.05, P_corr > 0.05). Four bacterial species occurred more frequently in AgP than in controls (p < 0.01, P_corr < 0.05). Elevated IL-10 levels were found in AgP patients, carriers of IL-10 −1087GG genotype, and PBMCs stimulated by periodontal bacteria (p < 0.05, P_corr > 0.05). We therefore conclude that a combination of genetic predisposition to the altered expression of IL-10 and the presence of specific periodontal bacteria may contribute to Th1/Th2 balance disruption and AgP development.

Differential expression of microRNAs in the saliva of patients with aggressive periodontitis: a pilot study of potential biomarkers for aggressive periodontitis

Purpose

The aim of this study was to compare microRNA (miRNA) gene expression in saliva using miRNA polymerase chain reaction (PCR) arrays in healthy and aggressive periodontitis (AP) patients.

Methods

PCR arrays of 84 miRNAs related to the human inflammatory response and autoimmunity from the saliva samples of 4 patients with AP and 4 healthy controls were performed. The functions and diseases related to the miRNAs were obtained using TAM 2.0. Experimentally validated targets of differentially expressed miRNAs were obtained from mirTarBase. Gene ontology terms and pathways were analyzed using ConsensusPathDB.

Results

Four downregulated miRNAs (hsa-let-7a-5p, hsa-let-7f-5p, hsa-miR-181b-5p, and hsa-miR-23b-3p) were identified in patients with AP. These miRNAs are associated with cell death and innate immunity, and they target genes associated with osteoclast development and function.

Conclusions

This study is the first analysis of miRNAs in the saliva of patients with AP. Identifying discriminatory human salivary miRNA biomarkers reflective of periodontal disease in a non-invasive screening assay is crucial for the development of salivary diagnostics. These data provide a first step towards the discovery of key salivary miRNA biomarkers for AP.

Transcription modulation by CDK9 regulates inflammatory genes and RIPK3-MLKL-mediated necroptosis in periodontitis progression

Cyclin-dependent kinase 9 (CDK9), one crucial molecule in promoting the transition from transcription pausing to elongation, is a critical modulator of cell survival and death. However, the pathological function of CDK9 in bacterial inflammatory diseases has never been explored. CDK9 inhibition or knock-down attenuated Porphyromonas gingivalis-triggered inflammatory gene expression. Gene-expression microarray analysis of monocytes revealed that knock-down of CDK9 not only affected inflammatory responses, but also impacted cell death network, especially the receptor-interacting protein kinase 3 (RIPK3)-mixed lineage kinase domain-like (MLKL)-mediated necroptosis after P. gingivalis infection. Inhibition of CDK9 significantly decreased necroptosis with downregulation of both MLKL and phosphorylated MLKL. By regulating caspase-8 and cellular FLICE inhibitory protein (cFLIP), key molecules in regulating cell survival and death, CDK9 affected not only the classic RIPK1-RIPK3-mediated necroptosis, but also the alternate TIR-domain-containing adapter-inducing interferon-β-RIPK3-mediated necroptosis. CDK9 inhibition dampened pro-inflammatory gene production in the acute infection process in the subcutaneous chamber model in vivo. Moreover, CDK9 inhibition contributed to the decreased periodontal bone loss and inflammatory response induced by P. gingivalis in the periodontal micro-environment. In conclusion, by modulating the RIPK3-MLKL-mediated necroptosis, CDK9 inhibition provided a novel mechanism to impact the progress of bacterial infection in the periodontal milieu.

Azithromycin and Full-Mouth Scaling For the Treatment of Generalized Stage III and IV Periodontitis: A 6-Month Randomized Comparative Clinical Trial

Abstract The effectiveness of azithromycin combined with full-mouth scaling procedures was compared to quadrant-wise scaling combined with the same dosage of azithromycin when treating periodontitis patients over a 6-month period. In this randomized clinical trial study, thirty-four individuals diagnosed with generalized stage III and IV periodontitis underwent baseline, 3-month, and 6-month post-treatment examinations. The study population was randomly assigned to either full-mouth scaling (FMS) or quadrant-wise scaling and root planning (QSRP) in addition to their taking of systemic azithromycin (500 mg/day) for three consecutive days. Periodontal probing depth (PD), clinical attachment level (CAL), gingival index (GI), and plaque index (PI) were monitored along with the quantification of total bacterial load and red complex bacterial species (Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) in subgingival samples by real time polymerase chain reaction. The volume of gingival crevicular fluid (GCF) was also monitored over time. The primary outcomes included improvements of PD and CAL. Data was statistically analyzed through a repeated-measures analysis of variance (ANOVA) test, multiple least significant difference (LSD) comparisons, Kruskal-Wallis, Friedman, and paired Student t-tests (p<0.05). FMS and QSRP provided similar PD, CAL, GI, PI, and GCF improvements. After treatment, the FMS group displayed lower mean values of total bacterial load and red complex bacterial species in comparison to the QSRP group. FMS and QSRP in conjunction with systemic azithromycin appeared to be an effective and reliable short-term therapeutic approach for the treatment of generalized stage III and IV periodontitis. However, FMD demonstrated superiority in regard to the 6-month antibacterial effects when compared to QSRP.

The effect of nonsurgical periodontal therapy on hepcidin and on inflammatory and iron marker levels

Serum hepcidin levels may increase in response to infection and inflammation. The present study investigated the effect of nonsurgical periodontal therapy (NSPT) on levels of serum hepcidin, inflammatory markers, and iron markers. An interventional study was conducted on 67 patients (age 30-65 years) without other diseases, except for chronic periodontitis (CP). Patients were allocated to either CP or control groups. The CP group received supragingival and subgingival scaling and root planing procedures, whereas the control group received supragingival scaling. Probing depth (PD), bleeding on probing, clinical attachment level (CAL), visible plaque index (VPI), serum hepcidin and interleukin-6 (IL-6) levels, high-sensitivity C-reactive protein (hs-CRP), hematological markers, and iron markers were measured at baseline and at 90 days after NSPT. The CP group had statistically significant lower mean values for mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) (p ≤ 0.05). The control group had statistically significant reductions in hemoglobin, hematocrit, MCV, and MCH (p ≤ 0.05). Serum hepcidin, IL-6, and erythrocyte sedimentation rate (ESR) levels were significantly decreased in both groups after NSPT. Periodontal markers were more markedly reduced in the CP group compared with the control group (p ≤ 0.05). These findings suggest that NSPT may reduce the serum levels of IL-6, hepcidin, and periodontal parameters.

Periodontal tissue destruction in aggressive periodontitis: Determination of gene or environmental factors

Aim

This study observed the role of defective neutrophil function in aggressive periodontitis through FPR1 gene polymorphism and the level of Il-8 compared with the role of dental plaque presence towards periodontal tissue damage (Clinical Attachment Loss/CAL) in patients in Indonesia.

Methods

Case-control study was used to detect differences in polymorphism expression of FPR1 gene, the level of Il-8, dental plaque, and Clinical Attachment Loss/CAL from 32 Aggressive Periodontitis (AP) and 29 Non-Aggressive Periodontitis (NAP) samples, selected with consecutive sampling method. Polymorphism was identified using polymerase chain reaction (PCR) technique, and the level of IL-8 in the gingival crevicular fluid was identified using the enzyme-linked immunosorbent assay (ELISA) test. The Clinical Attachment Loss was analysed by using William periodontal probe, and the oral environment analysis was performed by using the OHI-S plaque index. Statistical analysis was used to determine the significance of the polymorphism difference of FPR gene, Il-8, Plaque and CAL amongst all subjects and also the control and correlations among these factors.

Results

The results showed that in the Aggressive Periodontitis (AP), the presence of the polymorphism of c576 T > C > G of FPR1 gene caused as much as 5.04 times higher occurrence of aggressive periodontitis (p = 0.006; OR = 5.040 (1.51–16.74)). The low level of Il-8 (below 0.064 pg/μl), showed as much as 34.5 times higher occurrence of aggressive periodontitis (OR = 34.5 (6.76–176.08)). The oral hygiene of the AP samples were better significantly (p = 0.002), and on the Clinical Attachment Loss (CAL) sample was even more (p = 0.02). The polymorphism of c301 G > C of FPR1 gene correlated with the CAL (r = 0.37; p = 0.039). The polymorphism of c576 T > C > G correlated significantly with the Il-8 (r = 0.5; p = 0.0287). The polymorphism of c348 T > C correlated significantly with the dental plaque (r = 0.355; p = 0.049), whereas the dental plaque correlation with CAL was not significant.

Conclusion

The research conclusion showed that in aggressive periodontitis, genetic and environmental factors were correlated with the cause of periodontal tissue injury, and the role of genetic factors was more prominent on the injury.

1,25-dihydroxyvitamin-D3 promotes neutrophil apoptosis in periodontitis with type 2 diabetes mellitus patients via the p38/MAPK pathway

BACKGROUND

Abnormal neutrophils are involved in many chronic endocrine diseases, including type 2 diabetes mellitus (T2DM), and in periodontitis (PD), which is a chronic inflammatory disease in which neutrophils play a vital role. The p38 mitogen-activated protein kinase (MAPK) signaling pathway participates in the apoptosis of many inflammatory cells. Additionally, 1,25-dihydroxyvitamin-D3 (1,25VitD3) as a regulator can induce responses to infection and tumor cell apoptosis. However, the effect of 1,25VitD3 in the pathogenic relationship between T2DM and PD remains unclear. The aim of this study was to assess the effect of 1,25VitD3 on neutrophil apoptosis in patients with T2DM and PD and the p38-MAPK-relevant signaling pathway mechanism in this process in vitro.

METHODS

Neutrophils were stained with Wright's stain, and apoptosis was detected by flow cytometry and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining. Apoptosis- and p38-related mRNAs and proteins were examined by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blotting and ELISA. The internal relationships were analyzed using a linear regression equation and Pearson's correlation coefficient.

RESULTS

The highest rate of neutrophil apoptosis occurred in cultures treated with 10 mol/L 1,25VitD3 in the T2DM-PD group. The apoptosis rate in the T2DM-PD-p38 inhibitor group was higher than that in the healthy control group. Western blot, ELISA and qRT-PCR results showed that the mRNA and protein expression profiles of Caspase-3 and Bax were highly up-regulated and that Bcl-2 was down-regulated in the T2DM-PD-p38 inhibitor group. The expression levels of apoptotic mRNAs and proteins in the T2DM and T2DM-PD groups were significantly higher than those in the T2DM-p38 and T2DM-PD-p38 inhibitor groups. 1,25VitD3-induced neutrophil apoptosis and phosphorylated p38 (p-p38) expression were partially inhibited by the p38 inhibitor. Expression levels of apoptosis-related genes and p-p38 in neutrophils were positively associated with increasing concentrations of 1,25VitD3. p-p38 protein expression was positively associated with the level of serum 1,25VitD3.

CONCLUSION

1,25VitD3 could promote peripheral blood neutrophil apoptosis in patients with T2DM and PD through activation of the p38-MAPK signaling pathway in vitro.

Comparison of miRNA expression profiles in individuals with chronic or aggressive periodontitis

OBJECTIVES

MicroRNAs (miRNAs) may play an important role in inflammatory response. However, the involvement of miRNAs in the pathogenesis of periodontitis is unclear. The present study aimed to compare the miRNA expression profiles in individuals with chronic (CP) or aggressive (AP) periodontitis.

MATERIALS AND METHODS

Eighteen non-smoker individuals (CP = 9 and AP = 9) without any history of systemic diseases or previous periodontal therapies were selected at the Clinics of Periodontology from the Federal University of Minas Gerais. Gingival tissue samples were collected during the initial periodontal therapy. miRNAs were isolated, and expression patterns of 754 miRNAs were assessed with a quantitative miRNA PCR array. miRNAs expression profiles were compared between CP and AP groups.

RESULTS

There were no differences observed in the miRNAs expression profiles between CP and AP (p > 0.05). According to the microarray analyses, the most expressed miRNAs in both groups were hsa-miR-1274b, hsa-let-7b-5p, hsa-miR-24-3p, hsa-miR-19b-3p, hsa-miR-720, hsa-miR-126-3p, hsa-miR-17-3p and hsa-miR-21-3p.

CONCLUSION

Findings suggested no differences in miRNAs expression profiles between chronic and aggressive forms of periodontitis. The overexpression of specific miRNAs could provide insights into the pathogenesis of both forms of the disease.

Identification of genetic risk factors of aggressive periodontitis using genomewide association studies in association with those of chronic periodontitis

To identify the genetic risk factors for aggressive periodontitis (AgP), it is important to understand the progression and pathogenesis of AgP. The purpose of this review was to summarize the genetic risk factors for AgP identified through a case-control genomewide association study (GWAS) and replication study. The initial studies to identify novel AgP risk factors were potentially biased because they relied on previous studies. To overcome this kind of issue, an unbiased GWAS strategy was introduced to identify genetic risk factors for various diseases. Currently, three genes glycosyltransferase 6 domain containing 1 (GLT6D1), defensin α1 and α3 (DEFA1A3), and sialic acid-binding Ig-like lectin 5 (SIGLEC5) that reach the threshold for genomewide significance have been identified as genetic risk factors for AgP through a case-control GWAS.

Effects of quorum-sensing inhibition on experimental periodontitis induced by mixed infection in mice

This study aimed to verify, in in vivo settings, whether quorum-sensing inhibition molecules could attenuate alveolar bone loss induced by Porphyromonas gingivalis/Fusobacterium nucleatum co-infection and reduce the bacterial colonization of periodontal tissues. In BALB/c mice, periodontitis was induced through oral inoculation with P. gingivalis and F. nucleatum six times during a 42-d period. Quorum sensing inhibitors (a furanone compound and D-ribose) were administered simultaneously with bacterial infection. Linear and volumetric modifications of interproximal alveolar bone levels were compared between groups using micro-computed tomography. Total bacteria, and P. gingivalis and F. nucleatum DNA in periodontal tissues, were quantified using real-time PCR. Radiographic linear measurements demonstrated a significant reduction of alveolar bone loss, of approximately 40%, in mice treated with quorum sensing inhibitors when compared with the co-infection group. This was confirmed by a significant increase of residual bone volume in the test group. While total bacterial genes in the treatment group significantly decreased by 93% in periodontal tissue samples when quorum sensing inhibitors were administered, no significant differences of P. gingivalis DNA were found. Quorum sensing inhibitors reduced periodontal breakdown and bacterial infection in periodontal tissues after co-infection with P. gingivalis and F. nucleatum.

Analysis of salivary phenotypes of generalized aggressive and chronic periodontitis through nuclear magnetic resonance-based metabolomics

BACKGROUND

Recent findings about the differential gene expression signature of periodontal lesions have raised the hypothesis of distinctive biological phenotypes expressed by generalized chronic periodontitis (GCP) and generalized aggressive periodontitis (GAgP) patients. Therefore, this cross-sectional investigation was planned, primarily, to determine the ability of nuclear magnetic resonance (NMR) spectroscopic analysis of unstimulated whole saliva to discriminate GCP and GAgP disease-specific metabolomic fingerprint and, secondarily, to assess potential metabolites discriminating periodontitis patients from periodontally healthy individuals (HI).

METHODS

NMR-metabolomics spectra were acquired from salivary samples of patients with a clinical diagnosis of GCP (n = 33) or GAgP (n = 28) and from HI (n = 39). The clustering of HI, GCP, and GAgP patients was achieved by using a combination of the Principal Component Analysis and Canonical Correlation Analysis on the NMR profiles.

RESULTS

These analyses revealed a significant predictive accuracy discriminating HI from GCP, and discriminating HI from GAgP patients (both 81%). In contrast, the GAgP and GCP saliva samples seem to belong to the same metabolic space (60% predictive accuracy). Significantly lower levels (P < 0.05) of pyruvate, N-acetyl groups and lactate and higher levels (P < 0.05) of proline, phenylalanine, and tyrosine were found in GCP and GAgP patients compared with HI.

CONCLUSIONS

Within the limitations of this study, CGP and GAgP metabolomic profiles were not unequivocally discriminated through a NMR-based spectroscopic analysis of saliva.

Prescription of Antibiotics for Periodontal Disease among Dentists in the Region of Tirana

BACKGROUND:

Periodontal disease has been and will be a challenge for dentists in the entirety of oral pathologies. To date, there is no data regarding the prescription of antibiotics for periodontitis in the district of Tirana.

AIM:

Evaluate aspects related to the pattern of prescription of antibiotics among dentists in Tirana region for periodontitis.

METHODS:

Prescriptions from dental practitioners were collected from 25 pharmacies, randomly selected. The only prescription containing a diagnosis of periodontitis, with at least one antibiotic given, was included in the study. Data analysis was done with SPSS 20.

RESULTS:

Out of 1159 initial prescriptions, only 314 met the selection criteria. The average age of patients was 39.91 ± 15.21 years. Mean duration of therapies was 5.57 ± 1.5 days. The most common form of prescription was one broad-spectrum antibiotic (74.5%), combined antibiotics therapy (22.3%) and narrow-spectrum antibiotic (3.2%). Combined antibiotics involved the use of Metronidazole with Amoxicillin (12.1%) and Metronidazole with Spiramycin (10.2%). Significant differences in the patterns of prescription were identified in relation with patient age and therapy duration (P < 0.05). No statistical difference was found in the patient’s gender and the typology of the therapy (P > 0.05).

CONCLUSIONS:

Our study shows prescription characteristics of antibiotics for periodontal disease by dentists in Tirana for the first time. Amoxycillin is the most prescribed antibiotic, followed by amoxicillin with clavulanic acid. We found variation in dosage, frequency and duration for all antibiotics used, and perceptible discrepancies between observed and recommended practice. Guidelines on rational antibiotic use are needed for dental practitioners in Tirana and the Republic of Albania for better management of periodontitis and resistance prevention.

Analysis of metabolic profiles of generalized aggressive periodontitis

BACKGROUND AND OBJECTIVE

The specific pathogenesis of generalized aggressive periodontitis (GAgP) has not yet been clarified, and few studies have focused on the association between GAgP and metabolomics. To elucidate the roles of metabolic profiles in the status of GAgP, this study aimed to identify the differential metabolic profiles between patients with GAgP and healthy controls using an untargeted metabolomic profiling method.

MATERIAL AND METHODS

Serum and gingival crevicular fluid samples were collected from healthy controls (n = 20) and patients with GAgP (n = 20) in this cross-sectional study. The relative levels of biomarkers in the samples were measured by gas chromatography-mass spectrometry. Principal components analysis and orthogonal partial least-squares discriminant analysis were used for statistical analysis. Metabolites were analysed qualitatively using the FiehnLib and NIST databases. Full-mouth probing depth and clinical attachment loss were recorded as indexes of periodontal disease.

RESULTS

A total of 349 metabolites were qualitatively detected in the gingival crevicular fluid samples, and 200 metabolites were detected in the serum samples. Compared with healthy controls, patients with GAgP showed significant increases in serum urea and allo-inositol levels. In contrast, glutathione, 2,5-dihydroxybenzaldehyde, adipic acid and 2-deoxyguanosine levels were decreased in patients with GAgP. In the gingival crevicular fluid samples, noradrenaline, uridine, α-tocopherol, dehydroascorbic acid, xanthine, galactose, glucose-1-phosphate and ribulose-5-phosphate levels were increased in patients with GAgP, while thymidine, glutathione and ribose-5-phosphate levels were decreased.

CONCLUSION

The metabolomics analysis by gas chromatography-mass spectrometry is an effective and minimally non-invasive way to differentiate the metabolites characteristic of patients with GAgP. Both serum and gingival crevicular fluid metabolomics are significantly different between patients with GAgP and healthy controls. These metabolic profiles have great potential in detecting GAgP and helping to understand its underlying mechanisms.

Periodontitis: facts, fallacies and the future

This volume of Periodontology 2000 represents the 25th anniversary of the Journal, and uses the occasion to assess important advancements in periodontology over the past quarter-century as well as the hurdles that remain. Periodontitis is defined by pathologic loss of the periodontal ligament and alveolar bone. The disease involves complex dynamic interactions among active herpesviruses, specific bacterial pathogens and destructive immune responses. Periodontal diagnostics is currently based on clinical rather than etiologic criteria, and provides limited therapeutic guidance. Periodontal causative treatment consists of scaling, antiseptic rinses and occasionally systemic antibiotics, and surgical intervention has been de-emphasized, except perhaps for the most advanced types of periodontitis. Plastic surgical therapy includes soft-tissue grafting to cover exposed root surfaces and bone grafting to provide support for implants. Dental implants are used to replace severely diseased or missing teeth, but implant overuse is of concern. The utility of laser treatment for periodontitis remains unresolved. Host modulation and risk-factor modification therapies may benefit select patient groups. Patient self-care is a critical part of periodontal health care, and twice-weekly oral rinsing with 0.10-0.25% sodium hypochlorite constitutes a valuable adjunct to conventional anti-plaque and anti-gingivitis treatments. A link between periodontal herpesviruses and systemic diseases is a strong biological plausibility. In summary, research during the past 25 years has significantly changed our concepts of periodontitis pathobiology and has produced more-effective and less-costly therapeutic options.

Worlds Apart - Transcriptome Profiles of Key Oral Microbes in the Periodontal Pocket Compared to Single Laboratory Culture Reflect Synergistic Interactions

Periodontitis is a worldwide prevalent oral disease which results from dysbiosis of the periodontal microbiome. Some of the most active microbial players, e.g., Porphyromonas gingivalis, Treponema denticola, and Fusobacterium nucleatum, have extensively been studied in the laboratory, but it is unclear to which extend these findings can be transferred to in vivo conditions. Here we show that the transcriptional profiles of P. gingivalis, T. denticola, and F. nucleatum in the periodontal niche are distinct from those in single laboratory culture and exhibit functional similarities. GO (gene ontology) term enrichment analysis showed up-regulation of transporters, pathogenicity related traits and hemin/heme uptake mechanisms for all three species in vivo. Differential gene expression analysis revealed that cysteine proteases, transporters and hemin/heme-binding proteins were highly up-regulated in the periodontal niche, while genes involved in DNA modification were down-regulated. The data suggest strong interactions between those three species regarding protein degradation, iron up-take, and mobility in vivo, explaining their enhanced synergistic pathogenicity. We discovered a strikingly high frequency of Single Nucleotide Polymorphisms (SNPs) in vivo. For F. nucleatum we discovered a total of 127,729 SNPs in periodontal niche transcripts, which were found in similar frequency in health and disease and covered the entire genome, suggesting continuous evolution in the host. We conclude that metabolic interactions shape gene expression in vivo. Great caution is required when inferring pathogenicity of microbes from laboratory data, and microdiversity is an important adaptive trait of natural communities.