Advances in the pathogenesis of periodontitis: summary of developments, clinical implications and future directions

Fibulins and matrilins are novel structural components of the periodontium in the mouse

Periodontitis refers to inflammatory disease of the periodontal structures (the gingiva, dental cementum, periodontal ligament (PDL) and alveolar bone) that ultimately leads to their destruction. Whereas collagens are well-examined main components of the periodontium, little is known about the other structural proteins that make up this tissue. The aim of this study was to identify new extracellular matrix (ECM) components, including fibulins and matrilins, in the periodontium of mice. After sacrificing 14 mice (Sv/129 strain), jaws were prepared. Each tissue sample contained a molar and its surrounding alveolar bone. Immunohistochemistry was carried out on paraffin-embedded sections. Our results show that mice exhibit fibulin-3, -4 and -5 and matrilin-1, -2, -3 and -4 in PDL and in blood vessels of alveolar bone and PDL as well as in the pericellular matrix of osteocytes and cementocytes. In dental cementum, only fibulin-4 is expressed. For the first time, we show that fibulin-3, -4 and -5 and matrilin-1, -2, -3 and -4 are essential components of the periodontal tissues. Our findings indicate an association of these proteins with collagens and oxytalan fibers that might be of future interest in regenerative periodontitis therapy.

Mucosal immunization with a flagellin-adjuvanted Hgp44 vaccine enhances protective immune responses in a murine Porphyromonas gingivalis infection model

Chronic periodontitis is caused by interactions between the oral polymicrobial community and host factors. Periodontal diseases are associated with dysbiotic shift in oral microbiota. Vaccination against periodontopathic bacteria could be a fundamental therapeutic to modulate polymicrobial biofilms. Because oral cavity is the site of periodontopathic bacterial colonization, mucosal vaccines should provide better protection than vaccines administered systemically. We previously reported that bacterial flagellin is an excellent mucosal adjuvant. In this study, we investigated whether mucosal immunization with a flagellin-adjuvanted polypeptide vaccine induces protective immune responses using a Porphyromonas gingivalis infection model. We used the Hgp44 domain polypeptide of Arg-gingipain A (RgpA) as a mucosal antigen. Intranasal (IN) immunization induced a significantly higher Hgp44-specific IgG titer in the serum of mice than sublingual (SL) administration. The co-administration of flagellin potentiated serum IgG responses for both the IN and SL vaccinations. On the other hand, the anti-Hgp44-specific IgA titer in the saliva was comparable between IN and SL vaccinations, suggesting SL administration as more compliant vaccination route for periodontal vaccines. The co-administration of flagellin significantly potentiated the secretory IgA response in saliva also. Furthermore, mice administered a mixture of Hgp44 and flagellin via the IN and SL routes exhibited significant reductions in alveolar bone loss induced by live P. gingivalis infections. An intranasally administered Hgp44-flagellin fusion protein induced a comparable level of Hgp44-specific antibody responses to the mixture of Hgp44 and flagellin. Overall, a flagellin-adjuvanted Hgp44 antigen would serve an important component for a multivalent mucosal vaccine against polymicrobial periodontitis.

Angelica dahurica ameliorates the inflammation of gingival tissue via regulation of pro-inflammatory mediators in experimental model for periodontitis

ETHNOPHARMACOLOGICAL RELEVANCE

Anti-inflammatory effects of Angelica dahurica (AD) have been reported in previous studies. In this study, we investigated the anti-inflammatory effects of AD on periodontitis.

MATERIALS AND METHODS

Male Sprague-Dawley rats aged 7 weeks (n=7) were subjected to ligature around bilateral mandibular first molars. 1 and 100mg/mL of AD were topically applied to first molars for 14 days. Histological changes were observed in gingival epithelial layer, and the thickness of the gingival epithelial layer as well as the number of epithelial cells were quantified. To investigate the mRNA expression of pro-inflammatory cytokines in gingival tissues, reverse transcriptase polymerase chain reaction was performed. To confirm the anti-inflammatory effects of AD, pro-inflammatory mediators including cytokines and NF-kB, COX-2, and iNOS were analyzed in LPS-stimulated Raw 264.7 cells.

RESULTS

Topical application of AD attenuated not only the thickness of epithelial layer, also the number of epithelial cells in gingival tissue. The expressions of IL-1β, IL-6, IL-8, and IFN-γ in gingiva were significantly reduced by AD treatment. Additionally, the expressions of IL-1β, IL-6, IL-8 and IFN-γ mRNA were inhibited by AD in LPS-treated RAW264.7 macrophage cells. Furthermore, AD treatment decreased LPS-induced elevation of NF-κB, COX-2 and iNOS protein levels in RAW264.7 cells.

CONCLUSION

Taken together, AD application ameliorated the hyperplasia of gingival epithelial layer by down-regulating pro-inflammatory mediators. AD might have therapeutic potentials for periodontal diseases.

Adjunctive Effect of Autologus Platelet-Rich Fibrin to Barrier Membrane in the Treatment of Periodontal Intrabony Defects

BACKGROUND AND AIM

Autologous platelet-rich fibrin (PRF) and barrier membranes in the treatment of intrabony defects in chronic periodontitis patients have shown significant clinical benefits. This study evaluates the additive effect of autologous PRF in combination with a barrier membrane versus the use of barrier membrane alone for the treatment of intrabony defects in chronic periodontitis patients.

METHODS

A randomized split-mouth design was used. Sixteen patients with 32 paired intrabony defects were included. In each patient 1 defect was treated using a resorbable collagen membrane along with PRF (test group) and the other defect by guided tissue regeneration alone (control group). The following clinical parameters were measured at baseline and after 9 months: plaque index, modified sulcus bleeding index, probing pocket depth, clinical attachment level, and gingival marginal level. The radiographic defect depth was also assessed at baseline and after 9 months.

RESULTS

Test group showed a statistically significant improvement for probing depth (P = 0.002), clinical attachment level (P = 0.001), and radiographic defect depth (P < 0.001) after 9 months as compared with the control sites. Radiographic defect depth reduction was 58.19 ± 13.24% in the test group as compared with 24.86 ± 9.94% reduction in the control group.

CONCLUSIONS

The adjunctive use of PRF in combination with barrier membrane is more effective in the treatment of intrabony defects in chronic periodontitis as compared with barrier membrane alone.

Pro-resolving mediators in the regulation of periodontal disease

Periodontitis is an inflammatory disease of the supporting structures of the dentition that is initiated by bacteria that form a biofilm on the surface of the teeth. The pathogenesis of the disease is a result of complex interactions between the biofilm and the host response that results in dysbiosis of the microbiome and dysregulation of the inflammatory response. Current data suggest that the excess inflammation associated with periodontitis is due to a failure of resolution of inflammation pathways. In this review, the relationship between inflammation and microbial dysbiosis is examined in the context of pro-inflammation and pro-resolution mediators and their ability to modify the course of disease. The impact of local oral inflammation on systemic inflammation and the relationship of periodontitis to other inflammatory diseases, including type 2 diabetes and cardiovascular disease is reviewed. Active resolvers of inflammation, including the lipoxins and resolvins, show great promise as therapeutics for the treatment of periodontitis and other inflammatory diseases.

The number of microvascular complications is associated with an increased risk for severity of periodontitis in type 2 diabetes patients: Results of a multicenter hospital-based cross-sectional study

Aims/Introduction

To explore the relationships between periodontitis and microvascular complications as well as glycemic control in type 2 diabetes patients.

Materials and Methods

This multicenter, hospital‐based, cross‐sectional study included 620 patients with type 2 diabetes. We compared the prevalence and severity of periodontitis between patients with ≥1 microvascular complication and those without microvascular complications. We also compared the prevalence and severity of periodontitis among patients with different degrees of glycemic control.

Results

After adjusting for confounding factors, multiple logistic regression analysis showed that the severity of periodontitis was significantly associated with the number of microvascular complications (odds ratio 1.3, 95% confidence interval 1.1–1.6), glycated hemoglobin ≥8.0% (64 mmol/mol; odds ratio 1.6; 95% confidence interval 1.1–2.3), and older age (≥50 years; odds ratio 1.7; 95% confidence interval 1.1–2.6). However, the prevalence of periodontitis was not significantly associated with the number of microvascular complications, but was associated with male sex, high glycated hemoglobin (≥8.0% [64 mmol/mol]), older age (≥40 years), longer duration of diabetes (≥15 years) and fewer teeth (≤25). Furthermore, propensity score matching for age, sex, diabetes duration and glycated hemoglobin showed that the incidence of severe periodontitis was significantly higher among patients with microvascular complications than among those without microvascular complications (P < 0.05).

Conclusions

The number of microvascular complications is a risk factor for more severe periodontitis in patients with type 2 diabetes, whereas poor glycemic control is a risk factor for increased prevalence and severity of periodontitis.

Root abnormalities and nonsurgical management of generalized aggressive periodontitis

To investigate long-term nonsurgical treatment outcomes in patients with generalized aggressive periodontitis (GAgP) and the impact of root abnormalities (RAs) and other patient-level factors in relation to GAgP progression. Patients (n = 64) from a GAgP cohort who completed active nonsurgical periodontal treatment and consented to re-evaluation after 3 to 11 (mean 5.3) years, were enrolled. RAs were identified using radiographs. Periodontal parameters (e.g., probing depths [PDs], and tooth loss [TL]) were investigated. Multivariate analysis was performed to identify factors contributing to TL and bone level alteration (∆BL). After treatment, the mean number of sites with PDs > 5 mm decreased from 54.3 to 17.2. Annual TL was 0.11/patient. Twenty-one patients (32.8%) had >4 teeth with root abnormalities (RA-teeth) and exhibited a higher risk for TL (univariate odds ration [OR] = 3.52, multivariate logistic OR = 6.57). Factors correlated to ∆BL were sites with residual PD > 5 mm (β = -0.400) and observation time (β = -0.210). Nonsurgical treatment provides beneficial outcomes in GAgP patients. Higher incidence of RAs and high prevalence of residual deep pockets have a negative impact on long-term outcomes.

PRACTICAL IMPLICATIONS

in cases of GAgP with residual deep pockets and high incidence of RAs, clinicians must emphasize that long-term outcomes of nonsurgical treatment may be compromised.

Epidemiology of Oral and Maxillofacial Infections

Dental caries and periodontal disease are the most common dental infections and are constantly increasing worldwide. Distribution, occurrence of dental caries, gingivitis, periodontitis, odontogenic infections, antibiotic resistance, oral mucosal infections, and microbe-related oral cancer are important to understand the public impact and methods of controlling such disease. Distribution of human papilloma virus and human immunodeficiency virus -related oral cancers in the US population is presented.

Lack of adjunctive effect of 0.1% sodium hypochlorite mouthwash combined to full-mouth ultrasonic debridement on supragingival plaque, gingival inflammation, and subgingival microbiota: A randomized placebo-controlled 6-month trial

To test the adjunctive effect of 0.1% sodium hypochlorite (NaOCl) mouthwash combined to full‐mouth ultrasonic debridement (FMUD) on reducing supragingival plaque, gingival inflammation, and microbial pathogens. In this 6‐month double‐blinded randomized clinical trial, individuals with gingivitis were assigned to test (n = 16) or placebo group (n = 16) and received FMUD followed by rinsing with 0.1% NaOCl (test) or distilled water (placebo), respectively, twice a day for 1 month. Full‐mouth periodontal examination was performed at baseline, 1, 3, and 6 months posttherapy, and subgingival plaque samples were obtained at the same time points and analysed for their composition by checkerboard. Differences between groups over time were examined by Student t test, Mann–Whitney, generalized linear model, and Friedman and chi‐square tests. Both therapeutic protocols resulted in significant clinical improvement in periodontal parameters over time, except for probing depth and attachment level, which had a slight mean increase of 0.2 mm (p < .01). No significant differences between groups were observed for any clinical parameter (p > .05). Most species (>65%) decreased similarly in levels in both groups over time. Significant reductions in the microbial complexes were seen mainly at 1 and 3 months, but they returned to baseline levels in both groups, except for the red and yellow complexes, and other oral species, which were kept in low levels at 6 months (p < .05). A 0.1% NaOCl mouthwash did not provide additional benefits to FMUD in reducing supragingival plaque, gingivitis, and/or microbial pathogens.

Role of PIN1 on in vivo periodontal tissue and in vitro cells

BACKGROUND

Although expression of peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (PIN1) was reported in bone tissue, the precise role of PIN1 in periodontal tissue and cells remain unclear.

MATERIAL & METHODS

To elucidate the roles of PIN1 in periodontal tissue, its expression in periodontal tissue and cells, and effects on in vitro 4 osteoblast differentiation and the underlying signaling mechanisms were evaluated.

RESULTS

PIN1 was expressed in mouse periodontal tissues including periodontal ligament cells (PDLCs), cementoblasts and osteoblasts at the developing root formation stage (postnatal, PN14) and functional stage of tooth (PN28). Treatment of PIN1 inhibitor juglone, and gene silencing by RNA interference promoted osteoblast differentiation in PDLCs and cementoblasts, whereas the overexpression of PIN1 inhibited. Moreover, osteogenic medium-induced activation of AMPK, mTOR, Akt, ERK, p38 and NF-jB pathways were enhanced by PIN1 siRNA, but attenuated by PIN1 overexpression. Runx2 expressions were induced by PIN1 siRNA, but downregulated by PIN1 overexpression.

CONCLUSION

In summary, this study is the first to demonstrate that PIN1 is expressed in developing periodontal tissue, and in vitro PDLCs and cementoblasts. PIN1 inhibition stimulates osteoblast differentiation, and thus may play an important role in periodontal regeneration.

Epstein-Barr virus is associated with periodontal diseases: A meta-analysis based on 21 case-control studies

Some controversies still exist between the detection of Epstein-Barr virus (EBV)'s DNA and risks of periodontal diseases. Hence, a comprehensive meta-analysis on all available literatures was performed to clarify the relationship between EBV and preidontitis.A comprehensive search was conducted within the PUBMED, EMBASE, and WANFANG databases up to October 10th, 2016 according to inclusion and exclusion criteria and finally 21 case-control literatures were obtained. The outcomes including odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. Publication bias was determined by Begg or Egger test. Sensitivity analysis was used to investigate reliability and stability of the results.According to the data from included trials, the association between overall increased risks of periodontitis and the detection of EBV was significant (OR = 6.199, 95% CI = 3.119-12.319, P < 0.001). In the disease-type analysis, the pooled ORs for chronic periodontitis and aggressive periodontitis were 6.586 (95% CI = 3.042-14.262, P < 0.001) and 8.361 (95% CI = 2.109-33.143, P = 0.003), respectively. In the subgroup analysis of ethnicity, our results suggested that high EBV-detecting frequencies were correlated with increased risks of periodontitis in Asians, Europeans, and Americans (P < 0.001). Subgroup analysis by the sample type showed that subgingival plaque (SgP) samples and tissue samples were available for EBV detecting (P < 0.001). Detecting EBV of samples in ≥5 (6) mm sites of periodontal pockets were easier than in ≤3-mm sites (P = 0.023).This meta-analysis indicates that high frequent detection of EBV correlates with increased risk of periodontal diseases. SgP and tissue are available for detecting EBV in patients of periodontitis. At last, our results suggest that detecting EBV of samples in =5 (6) mm sites of periodontal pockets are more sensitive than in ≤3-mm sites.

Antibiotic effects against periodontal bacteria in organ cultured tissue

Mechanical reduction of infectious bacteria by using physical instruments is considered the principal therapeutic strategy for periodontal disease; addition of antibiotics is adjunctive. However, local antibiotic treatment, combined with conventional mechanical debridement, has recently been shown to be more effective in periodontitis subjects with type 2 diabetes. This suggests that some bacteria may invade the inflamed inner gingival epithelium, and mechanical debridement alone will be unable to reduce these bacteria completely. Therefore, we tried to establish infected organ culture models that mimic the inner gingival epithelium and aimed to see the effects of antibiotics in these established models. Mouse dorsal skin epithelia were isolated, and periodontal bacteria were injected into the epithelia. Infected epithelia were incubated with test antibiotics, and colony-forming ability was evaluated. Results indicated that effective antibiotics differed according to injected bacteria and the bacterial combinations tested. Overall, in organ culture model, the combination of amoxicillin or cefdinir and metronidazole compensate for the effects of less effective bacterial combinations on each other. This in vitro study would suggest effective periodontal treatment regimens, especially for severe periodontitis.

An ex vivo evaluation of the efficacy of andrographolide in modulating differential expression of transcription factors and target genes in periodontal cells and its potential role in treating periodontal diseases

ETHANOPHARMACOLOGICAL RELEVANCE

Andrographolide is a herbal extract traditionally used in South Asian countries for treating inflammatory diseases.

AIM OF THE STUDY

To evaluate the efficacy of andrographolide in management of periodontal disease which is a highly prevalent oral disease.

MATERIALS AND METHODS

Periodontal ligament fibroblasts (PDLF) were cultured from healthy and diseased periodontium using explant culture methods. The safe dose of AG was determined using MTT assay. LPS (lipopolysaccharide) of the most important periodontopathogen, P gingivalis was used to activate NF-κB and STAT3 in PDLF. The efficacy of AG in inhibiting NF-κB and STAT3 was analyzed using immunofluorescence. Down regulation of expression of target genes of these transcription factors related to inflammation and bone resorption were analyzed using real time PCR.

RESULTS

AG up to the concentration of 25μM was found to be safe as determined by MTT assay. Statistically significant activation of NF-κB and STAT3 in cultured PDLF was observed in diseased group compared to healthy controls before and after LPS challenge. 5μM AG pretreatment significantly inhibited activation of NF-κB and STAT3 and down regulated expression of inflammatory and bone resorptive genes in cultured PDLF.

CONCLUSIONS

The findings of the present study propose the adjunctive use of a novel herbal drug andrographolide as a promising host modulation agent for periodontal therapy by inhibiting NF-κB and STAT3 activation and inhibition of inflammation and bone resorption related genes.

Salivary TNFα levels in groups of subjects with rheumatoid arthritis and chronic periodontitis

BACKGROUND

Rheumatoid arthritis (RA) and chronic periodontitis are the most common chronic inflammatory diseases with significant pathological and clinical similarities. Numerous studies have indicated a relationship between rheumatoid arthritis and periodontal disease. The aim of this study was to compare the TNF-α levels in saliva among patients with Rheumatoid arthritis (RA) and chronic periodontitis as well as healthy subjects.

METHODS

One hundred and seventy-one patients were enrolled in this cross-sectional study. Fifty-seven patients diagnosed of RA, 57 patients with chronic periodontitis and 57 healthy subjects. These patients have been examined with regard to TNF-α level from salivary samples. Their teeth were examined with regard to Plaque Index , Gingival Index, probing depth and clinical attachment level.All patients were non-smokers.

RESULTS

The results revealed a significant difference in all periodontal parameters among the three groups. The chronic periodontitis group showed a significantly higher value in all clinical periodontal parameters in comparison to both the RA and healthy groups. No significant difference was found between salivary TNF-α level among the three study groups.

CONCLUSIONS

Patients with chronic periodontitis had the highest periodontal indices. However there was no significant difference regarding the level of salivary TNF-α. Hence, suppression of proinflammatory cytokines might prove beneficial in suppressing periodontal diseases among RA patients.

Interleukin-6-174G/C Polymorphism Contributes to Periodontitis Susceptibility: An Updated Meta-Analysis of 21 Case-Control Studies

Introduction. Chronic Periodontitis (CP) is suggested to be related to gene variations. Present study aims to quantitatively estimate the association between interleukin-6- (IL-6-) 174G/C polymorphism and CP susceptibility. Materials and Methods. Pubmed, Embase, and Web of Science were searched up to May 2016. The meta-analyses were performed using STATA 12.0. Results. 21 studies were yielded. Significant associations were found under heterozygote comparison and dominant model in studies fulfilling HWE (GC versus GG: OR = 0.690, 95% CI = 0.560–0.849, P = 0.000; CC + GC versus GG: OR = 0.690, 95% CI = 0.568–0.838, P < 0.001); significant associations were found under heterozygote comparison and dominant model in Caucasian studies fulfilling HWE (GC versus GG: OR = 0.752, 95% CI = 0.577–0.980, P = 0.035; CC + GC versus GG: OR = 0.737, 95% CI = 0.576–0.944, P = 0.016); significant associations were found under allele comparison, heterozygote comparison, and dominant model in Brazilian population (C versus G: OR = 0.648, 95% CI = 0.497–0.845, P = 0.001; GC versus GG: OR = 0.621, 95% CI = 0.441–0.876, P = 0.007; CC + GC versus GG: OR = 0.649, 95% CI = 0.470–0.896, P = 0.009). Conclusion. IL-6 174 polymorphism is associated with CP susceptibility. In Brazilian and Caucasian population, IL-6 174 GG genotype plays as a risk factor to CP.

Relationship of Metabolic Syndrome to Periodontal Disease in Japanese Women: The Hisayama Study

Recent studies have suggested that several systemic conditions—such as obesity, hypertension, hyperlipidemia, and diabetes—are related to periodontitis. The objective of this study was to examine the relationship between periodontitis and 5 components of metabolic syndrome—abdominal obesity, triglyceride level, high-density lipoprotein cholesterol level, blood pressure, and fasting blood sugar level—in 584 Japanese women. In multivariate analyses, persons exhibiting more components of metabolic syndrome had significantly higher odds ratios for a greater pocket depth and clinical attachment loss than did those with no components; the odds ratios for a greater pocket depth and clinical attachment loss of the persons exhibiting 4 or 5 components were 6.6 (95% confidence interval = 2.6–16.4) and 4.2 (95% confidence interval = 1.2–14.8), respectively. These results indicate that metabolic syndrome increases risk of periodontitis, and suggest that people exhibiting several components of metabolic syndrome should be encouraged to undergo a periodontal examination.

The Severity of Periodontal Disease is Associated with the Development of Glucose Intolerance in Non-diabetics: The Hisayama Study

Inflammation is hypothesized to play a significant role in the development of type 2 diabetes; however, reports on clinical inflammatory conditions are limited. Studies have suggested that periodontitis affects glucose control in diabetics. This community-based study examined the relationship between periodontitis and glucose tolerance status, including changes in status. The relationship between periodontal condition and the results of a 75-g oral glucose tolerance test was examined in 961 adults in 1998. Deep pockets (mean pocket depth > 2.0 mm) were significantly associated with impaired glucose tolerance and with diabetes as compared with shallow pockets (< 1.3 mm). In the subgroup with normal glucose tolerance 10 years previously, subjects who subsequently developed impaired glucose tolerance were significantly more likely to have deep pockets. Deep pockets were closely related to current glucose tolerance status and the development of glucose intolerance.

Effect of Combined Therapy Using Diode Laser and Photodynamic Therapy on Levels of IL-17 in Gingival Crevicular Fluid in Patients With Chronic Periodontitis

Introduction: The aim of this study was to evaluate the efficacy of combination therapy of diode laser and photodynamic therapy (PDT) as an adjunct to scaling and root planing (SRP) on interleukin-17 (IL-17) levels in gingival crevicular fluid (GCF) in patients with chronic periodontitis. Methods: Thirty subjects with chronic periodontitis were included. All teeth received periodontal treatment comprising of SRP. Using a split mouth study design, the test group was additionally treated with a combination therapy of diode laser and PDT. GCF was collected to evaluate IL-17 levels at baseline and 3 months. Results: There was no difference in baseline values for levels of IL-17 in GCF in the test group and the control group. A significant decrease in GCF levels of IL-17 was observed in both treatment groups 3 months after treatment (P < 0.001). However, the treatment groups showed no significant difference (P > 0.05). Conclusion: Based on the results of the present study it was concluded that, GCF levels of IL-17 changed significantly after treatment regardless of treatment modality.

Biomarker levels in gingival crevicular fluid of subjects with different periodontal conditions: A cross-sectional study

OBJECTIVE

To compare five biomarker levels in gingival crevicular fluid (GCF) in different tooth-sites of subjects with healthy periodontium, aggressive periodontitis and severe chronic periodontitis, and to evaluate the value of these biomarker levels for diagnosis of the type and activity of periodontitis.

MATERIALS AND METHODS

Prior to therapy, GCF samples were collected using filter paper strip at different tooth-sites of 10 subjects with healthy periodontium (H), 15 with severe chronic periodontitis (CP) and 15 with aggressive periodontitis (AgP). The strips were weighed and the periodontal clinical parameters were recorded. Levels of interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α), C-reactive protein (CRP), and alkaline phosphatase (ALP) in GCF were assessed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The volumes of the GCF samples obtained in CP and AgP subjects were significantly higher than those from subjects with healthy periodontium (P<0.05). Levels of IL-6, TNF-α, CRP and ALP were significantly higher in the untreated disease sites in the CP and AgP groups compared to those in control sites in the H group, while IL-10 levels were lower in the CP and AgP groups than those in the control sites in the H group. However, the levels of all five biomarker levels showed significant correlation with the clinical parameters.

CONCLUSION

The measurement of five biomarker levels in GCF may facilitate overall screening of periodontitis patients in epidemiological studies and allow estimation of periodontitis activity.

Effect of non-surgical periodontal treatment on transferrin serum levels in patients with chronic periodontitis

Background. Transferrin is a negative acute phase protein, which decreases during inflammation and infection. The aim of the present investigation was to evaluate changes in the transferrin serum levels subsequent to non-surgical treatment of chronic periodontal disease. Methods. Twenty patients with chronic periodontitis and 20 systemically healthy subjects without periodontal disease, who had referred to Tabriz Faculty of Dentistry, were selected. Transferrin serum levels and clinical periodontal parameters (pocket depth, clinical attachment level, gingival index, bleeding index and plaque index) were measured at baseline and 3 months after non-surgical periodontal treatment. Data were analyzed with descriptive statistical methods (means ± standard deviations). Independent samples t-test was used to compare transferrin serum levels and clinical variables between the test and control groups. Paired samples t-test was used in the test group for comparisons before and after treatment. Statistical significance was set at P < 0.05. Results. The mean transferrin serum level in patients with chronic periodontitis (213.1 ± 9.2 mg/dL) was significantly less than that in periodontally healthy subjects (307.8 ± 11.7 mg/dL). Three months after periodontal treatment, the transferrin serum level increased significantly (298.3 ± 7.6 mg/dL) and approached the levels in periodontally healthy subjects (P < 0.05). Conclusion. The decrease and increase in transferrin serum levels with periodontal disease and periodontal treatment, respectively, indicated an inverse relationship between transferrin serum levels and chronic periodontitis.

Polymorphic Regions in Fc Gamma Receptor and Tumor Necrosis Factor-α Genes and Susceptibility to Chronic Periodontitis in a Cohort From South India

BACKGROUND

Polymorphisms in the immunoglobulin G Fc receptor II (FcGR) and tumor necrosis factor-α (TNFA) genes are known to influence pathogenesis and severity of several inflammatory conditions. Association of FcGR and TNFA gene polymorphisms with chronic periodontitis (CP) susceptibility has been found to be diverse among different ethnic populations. Objectives of the present study are to determine association of functional single nucleotide polymorphisms (SNPs) in FcGR and TNF-α genes with CP susceptibility in a cohort from South India.

METHODS

Polymorphisms of: 1) FCGR2A 131His/Arg (rs1801274); 2) FCGR2B 232Ile/Thr (rs1050501); 3) TNFA -1031T/C (rs1799964); and 4) TNFA -863C/A (rs1800630) were analyzed among patients with healthy gingiva (n = 176) and patients with CP (n = 177). Genotyping was performed using allele-specific real-time polymerase chain reaction assay. Association between CP and SNPs was examined by multivariable logistic regression analysis with adjustment for: 1) age; 2) sex; and 3) oral hygiene index (OHI). Epistatic interaction between FcGR polymorphisms and interleukin 1B (IL1B) +3954C/T (rs1143634) was assessed using multifactorial dimensionality reduction analysis.

RESULTS

Among four SNPs analyzed, only FCGR2A 131His/Arg showed significant association with CP in a dominant model (odds ratio: 1.6; 95% confidence interval: 1.028 to 2.530). This significance disappeared after correcting for multiple comparisons using Bonferroni analysis, or after adjusting for age, sex, and OHI. A significant redundant interaction between IL1B +3954 C/T and FCGR2A 131His/Arg was observed.

CONCLUSION

Study results suggest the variant form of the SNP in FCGR2A 131His/Arg, FCGR2B 232Ile/Thr, TNFA -1031T/C, and TNFA -863C/A are not associated with CP susceptibility in the selected cohort from South India.

Gingival crevicular fluid levels of cytokines/chemokines in chronic periodontitis: a meta-analysis

AIMS

To compare gingival crevicular fluid (GCF) cytokines/chemokines levels between periodontally healthy subjects and subjects diagnosed with chronic periodontitis (ChP), before and after non-surgical periodontal treatment, and to establish their predictive value for periodontal disease progression.

METHODS

Studies indexed in MEDLINE and EMBASE published in English, Portuguese and Spanish were eligible for this review. Database searches up to December 2015, and manual search of the reference list from reviews and selected articles was performed. Only studies providing data on GCF cytokines/chemokines levels in subjects diagnosed with ChP and periodontally healthy controls were included. Cross-sectional, case series, single-arm clinical studies, randomized controlled trials and prospective/retrospective cohort studies were included. Meta-analyses were conducted for those cytokines/chemokines with at least three available studies.

RESULTS

GCF levels of IL-1β, IL-6, IFN-γ and MCP-1/CCL2 were significantly higher in subjects diagnosed with ChP than periodontally healthy subjects. A significant decrease in GCF levels of IL-1β and IL-17 was observed after non-surgical periodontal treatment, whereas a significant increase was observed for IL-4.

CONCLUSION

Evidence for significant differences between periodontal health and ChP was observed for a few cytokines and one chemokine. No conclusions could be drawn with regards to increased risk of disease progression.

No association between periodontitis, preterm birth, or intrauterine growth restriction: experimental study in Wistar rats

BACKGROUND

The biologic plausibility of the possible association between periodontitis and adverse pregnancy outcomes has been assessed with the use of different experimental models. However, most experimental studies did not induce periodontitis in the animals but promoted an acute microbial challenge with selected periodontal pathogens or their products subcutaneous or intravenous or intraamniotic. The present study was then conducted to verify the biologic plausibility of such association by experimentally inducing periodontitis in Wistar rats.

OBJECTIVE

An experimental study on an animal model by the induction of periodontitis in 50% of sites and assessment of the presence of cytokines in the gingival tissue, serum, placenta, cord, and amniotic fluid was designed to test the null hypothesis that experimental periodontitis that is induced on rats does not result in adverse pregnancy outcomes.

STUDY DESIGN

Forty female Wistar rats were included in 2 groups: a periodontally healthy (without ligatures) and an experimentally induced periodontitis group (test, with ligatures). Forty-five days after the induction, the mating was initiated. Males were placed with females in the ratio of 1:2 for a period of 12 hours. The bodyweight of the female, from then on, was recorded daily. When the pregnancy was confirmed on day 20, laparotomy was performed. The amniotic fluid, placenta, umbilical cord, blood (serum) and maternal and gingival tissue samples were subjected to quantitative analysis for interleukin 1α, -6, -10, -4, -12p70, and -17a, tumor necrosis factor-α, and interferon-γ by multiplex methods. Mean scores, standard deviations, and standard errors for estimated measures were calculated. For cytokines analyses, the Mann-Whitney test was conducted to compare the concentration of the analytes from control and test groups in the different tissues samples. For comparison of cytokines reduction from gingival tissue to serum and from serum to placenta, the Wilcoxon Test was performed. Spearman's correlation was conducted among cytokines in the 5 different tissues that were evaluated.

RESULTS

The induced periodontitis in Wistar rats did not result in adverse outcomes of pregnancy. There were no statistically significant differences between groups in relation to prematurity, fetal, or birth weight. Regarding cytokines, there were no statistically significant differences in concentrations that were measured in each tissue between the groups with periodontitis and controls. Furthermore, all cytokine levels in the placenta, except interleukin-6, were diminished compared with the amniotic fluid or maternal serum, which suggested that the cytokines cannot easily be transferred via this tissue in maternal-fetal or fetomaternal direction. The fertility rate was reduced significantly in the group with periodontitis.

CONCLUSION

Periodontitis that is induced in rats is not a risk factor for preterm birth or low birthweight.

Antimicrobial photodynamic therapy using diode laser activated indocyanine green as an adjunct in the treatment of chronic periodontitis: A randomized clinical trial

INTRODUCTION

Clinical studies have shown the usefulness of antimicrobial photodynamic therapy (aPDT) as an adjunctive in periodontal therapy. These studies did not utilize indocyanine green (ICG) as a recently introduced photosensitizer. The aim of this study was to perform a full-mouth double-blind randomized controlled clinical study to test the efficacy of adjunctive aPDT with ICG compared with scaling and root planing (SRP) alone in chronic periodontitis treatment.

MATERIALS AND METHODS

Fifty patients were selected for this study. All patients received SRP. Then, each patient was randomly assigned to either the test group (aPDT+SRP) or the control group (SRP). aPDT was performed with a diode laser (wavelength: 810nm, power: 200mW) and ICG as photosensitizer. The adjunctive procedure was repeated after 7, 17 and 27 days. The clinical parameters including bleeding on probing (BOP), clinical attachment loss (CAL), plaque index (PI), probing pocket depth (PPD), full mouth plaque score (FMPS) and full mouth bleeding score (FMBS) were measured at baseline and after 1 and 3 months.

RESULTS

There were no significant differences between two groups at baseline. BOP, PPD and FMBS showed significant improvements in the test group (P≤0.001). In terms of PI, FMPS and CAL, no significant differences were observed between both groups (P≥0.05).

CONCLUSION

aPDT as an adjunctive approach yielded complete resolution of inflammation and significant reduction in periodontal pocket depth. However, aPDT had no additional advantages in clinical attachment gain and plaque score.

A meta-analysis of MMP-9 promoter -1562 C/T polymorphism on susceptibility of chronic periodontitis

Background

Although many studies have focused on the association of the MMP-9 promoter −1562 C/T polymorphism with the susceptibility and/or severity of chronic periodontitis (CP), results have been inconsistent. Therefore, a meta-analysis of all eligible studies was performed to derive a more precise estimation of the association between this polymorphism and CP risk.

Methods

All relevant studies were identified through a database search in PubMed, Medline, and Web of Science. All the full-text studies with appropriate analytical design, published in English, which evaluated the association of MMP-9 promoter −1562C/T polymorphism with CP risk using validated genotyping methods, and with non-duplicated data were selected for this study. A fixed-effect model was used to calculate pooled ORs in the absence of heterogeneity across included trials (P > 0.1 and I² < 50 %), otherwise the random-effect model was applied.

Results

In an overall meta-analysis, pooled ORs revealed that T variant in the MMP-9 promoter −1562 C/T polymorphism was associated with a significantly decreased risk for CP under all comparison models. In subgroup analyses by ethnicity, pooled ORs showed that a significant association of the MMP-9 promoter −1562 C/T polymorphism with CP risk was only detected in Caucasians and Asians but not in mixed population. In the subgroup analysis by severity of CP, pooled ORs indicated that T allele of the MMP-9 promoter −1562 C/T polymorphism was associated with decreased susceptibility to severe CP while there was no significant association between this polymorphism and moderate CP.

Conclusions

Our meta-analysis showed that T allele in the MMP-9 promoter −1562 C/T polymorphism might be a protective factor for CP, especially in Caucasians and Asians. Moreover, there was a significant association of the MMP-9 promoter −1562 C/T polymorphism with decreased susceptibility to severe CP, while the allelic and/or genotype distributions of this polymorphism were not associated with moderate CP.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-2135-3) contains supplementary material, which is available to authorized users.

Comparative assessment of the prevalence of periodontal disease in subjects with and without systemic autoimmune diseases: A case-control study

BACKGROUND

Immune mechanism shares a common pathway both for systemic autoimmune diseases and periodontal diseases. Scientific exploration of literature revealed limited studies on the association between systemic autoimmune diseases and periodontal diseases in India.

AIM

The aim of the study is to find whether the presence of systemic autoimmune diseases in an individual is a risk factor for the development of periodontal disease.

SETTINGS AND DESIGN

This was a hospital-based case-control study.

MATERIALS AND METHODS

A sample of 253 patients with systemic autoimmune diseases, attending the Rheumatology Department of Government General Hospital, Chennai-3, and 262 patients without systemic autoimmune diseases, attending the outpatient department of the Tamil Nadu Government Dental College and Hospital, Chennai-3, constituted the case and control groups, respectively. Age, gender, and oral hygiene status matching was done. Oral hygiene status was assessed using oral hygiene index (OHI) and periodontal status was assessed using community periodontal index (CPI) and loss of attachment (LOA) index.

STATISTICAL ANALYSIS

Statistical analysis was done using SPSS version 15 (SPSS Inc, 2006, Chicago).

RESULTS

Results showed 99.2% and 73.9% prevalence of gingivitis and periodontitis, respectively, in the case group as compared to 85.5% and 14.9%, respectively, in the control group. There is no linear relationship between OHI scores and prevalence of periodontitis (CPI and LOA scores) in the case group. Patients suffering from systemic autoimmune diseases showed more prevalence of periodontal diseases irrespective of oral hygiene scores.

CONCLUSION

It is postulated that the presence of systemic autoimmune diseases may pose a risk for the development of periodontal diseases.

A two-component system regulates gene expression of the type IX secretion component proteins via an ECF sigma factor

The periodontopathogen Porphyromonas gingivalis secretes potent pathogenic proteases, gingipains, via the type IX secretion system (T9SS). This system comprises at least 11 components; however, the regulatory mechanism of their expression has not yet been elucidated. Here, we found that the PorY (PGN_2001)-PorX (PGN_1019)-SigP (PGN_0274) cascade is involved in the regulation of T9SS. Surface plasmon resonance (SPR) analysis revealed a direct interaction between a recombinant PorY (rPorY) and a recombinant PorX (rPorX). rPorY autophosphorylated and transferred a phosphoryl group to rPorX in the presence of Mn²⁺. These results demonstrate that PorX and PorY act as a response regulator and a histidine kinase, respectively, of a two component system (TCS), although they are separately encoded on the chromosome. T9SS component-encoding genes were down-regulated in a mutant deficient in a putative extracytoplasmic function (ECF) sigma factor, PGN_0274 (SigP), similar to the porX mutant. Electrophoretic gel shift assays showed that rSigP bound to the putative promoter regions of T9SS component-encoding genes. The SigP protein was lacking in the porX mutant. Co-immunoprecipitation and SPR analysis revealed the direct interaction between SigP and PorX. Together, these results indicate that the PorXY TCS regulates T9SS-mediated protein secretion via the SigP ECF sigma factor.

Relationship between interleukin 1α levels in the gingival crevicular fluid in health and in inflammatory periodontal disease and periodontal inflamed surface area: A correlative study

Background:

Periodontitis has been suggested as a source of inflammation for pathological changes in distant sites. Interleukin-1 alpha (IL-1α) has shown to have specific roles in inflammation, immunity, tissue breakdown, and tissue homeostasis. This study assessed the correlation of periodontal inflamed surface area (PISA) index with the gingival crevicular fluid (GCF) levels of IL-1α, which would be helpful in evaluating the validity of PISA index in terms of reflection of the disease.

Materials and Methods:

A total of 40 subjects were recruited for this study and 20 subjects with healthy gingiva (Group I) served as controls and 20 subjects served as cases with periodontitis (Group II). Samples of GCF were obtained from one site in each patient by placing color-coded, calibrated, volumetric microcapillary pipettes extracrevicularly, and subjected to ELISA test.

Results:

There was a statistical significance for mean probing depth (PD) and periodontal epithelial surface area (PESA) (P < 0.01), mean bleeding on probing and PISA, IL-1α (P < 0.01) and PESA (P < 0.05) in Group I. Statistical significance was found between PISA and IL-1α in Group I (P < 0.01). A positive correlation was found in Group II between mean PD and mean attachment loss (P < 0.01), PISA, IL-1α and PESA (P < 0.01), PISA and IL-1α levels (P < 0.01) which was statistically significant.

Conclusion:

The inflammatory burden index was statistically significant in the periodontitis group correlating with higher IL-1α levels, which clearly indicates the validity of PISA index.

The Relationship of Bacterial Biofilms and Capsular Contracture in Breast Implants

Capsular contracture is a common sequelae of implant-based breast augmentation. Despite its prevalence, the etiology of capsular contracture remains controversial. Numerous studies have identified microbial biofilms on various implantable materials, including breast implants. Furthermore, biofilms have been implicated in subclinical infections associated with other surgical implants. In this review, we discuss microbial biofilms as a potential etiology of capsular contracture. The review also outlines the key diagnostic modalities available to identify the possible infectious agents found in biofilm, as well as available preventative and treatment measures.

Omega-3 fatty acids as an adjunct for periodontal therapy-a review

OBJECTIVES

The aim of this article is to present an overview of omega-3 fatty acids, their anti-inflammatory properties and potential use as an adjunct for periodontal therapy.

MATERIALS AND METHODS

A general literature search was conducted to provide an overview of omega-3 fatty acids, their metabolism and anti-inflammatory properties. A more specific literature search of PubMed and EMBASE was conducted to identify articles dealing studies investigating the effects of omega-3 fatty acids in the treatment of periodontitis in animals and humans and included cross-sectional, longitudinal and intervention designs.

RESULTS

To date, there is good emerging evidence that dietary supplementation with fish oil may be of some benefit and this is enhanced if combined with aspirin. All clinical intervention studies to date have been on small sample sizes, and this indicates there is need for larger and more robust clinical trials to verify these initial findings.

CONCLUSIONS

Dietary supplementation with fish oil could be a cost-effective adjunctive therapy to the management of periodontal disease.

CLINICAL RELEVANCE

The host modulatory properties of omega-3 fatty acids warrant further assessment of their use as an adjunct in the management of periodontitis.

Unique database study linking gingival inflammation and smoking in carcinogenesis

We investigated statistical association between gingival inflammation and cancer in a group of patients followed up for 26 years with the hypothesis that gingival inflammation affects carcinogenesis. Altogether, 1676 30- to 40-year-old subjects from Stockholm were clinically examined in 1985. In 2011, we compared the baseline oral examination and follow-up data with cancer diagnoses sourced from the Swedish national hospital register databases. Of 1676 individuals, 89 (55 women, 34 men) had got cancer by the year 2011. Women were found to be at higher risk for cancer than men. Smoking (expressed in pack-years) had been more prevalent in the cancer group than in those with no cancer diagnosis. Gingival index, marker of gingival inflammation, was higher in the cancer group than in subjects with no cancer. There were no significant differences between the groups regarding age, education, dental plaque and calculus index scores, or in the number of missing teeth. In multiple logistic regression analysis with cancer as the dependent variable and several independent variables, pack-years of smoking appeared to be a principal independent predictor with odds ratio (OR) 1.32 while gingival inflammation showed OR 1.29. Hence, our present findings showed that together with smoking, gingival inflammation indeed associated with the incidence of cancer in this cohort.

Glycemic control and the production of cytokines in diabetic patients with chronic periodontal disease

Objective: To evaluate the association of glycemic control and cytokine production in type 2 diabetic subjects with chronic periodontitis. Methods: Gingival biopsies were performed in 40 patients, divided into four groups: systemically healthy subjects without periodontal disease (S); systemically healthy patients with chronic periodontitis (P); patients with well-controlled type 2 diabetes mellitus (DM) with chronic periodontitis (C); poorly controlled type 2 diabetes mellitus with chronic periodontitis (D). The production of interleukin (IL) -4, -6, -10, -17 and interferon (IFN) -g was quantified by ELISA. Results: The production of IL-4, IL-10, IL-17 and INF-g was higher on group D when compared to other groups (p <0.05), which in turn were similar (p ³0.05). In addition, there was no difference in the production of IL-6 in any of the evaluated groups (p³0.05). Conclusion: Were observed significantly elevated levels of pro-inflammatory and anti-inflammatory cytokines in patients with poorly controlled type 2 diabetes and chronic periodontitis, demonstrating that glycemic control may be associated to the immune inflammatory response of sites with chronic periodontitis.

The Periodontal Status and Associated Systemic Health Problems among an Elderly Population Attending the Outpatient Clinics of a Dental School

AIM

Periodontal diseases are associated with systemic health and health behaviors; the purpose of this study was to investigate periodontal health status and its association with systemic health and health behaviors in the elderly.

MATERIALS AND METHODS

Data was collected from 300 random Case Western Reserve University (CWRU) dental school patient charts, aged 65 or higher. A modified WHO form was used to collect the date on: periodontal conditions using the community periodontal index (CPI), demographics, systemic health and certain health behaviors. Community periodontal index collected data for six sextants. Descriptive tests and bivariate analytic tests, Chi-square test and computation of odds ratio, investigated any association between certain periodontal conditions and demographic as well as systemic health attributes.

RESULTS

In the study cohort, the average age was 73.7 ± 6.8 years. Moderate periodontitis (38.9%) was the most prevalent periodontal health condition, while severe periodontitis was the least prevalent periodontal health (6.1%). Nearly 30% of the cohort had healthy periodontium. Only insurance status was associated with healthy periodontium (p < 0.05).

CONCLUSION

Moderate periodontitis was the most prevalent among the studied subjects. A positive association was found with the insurance status of the subjects and the healthy periodontium. No association was found between periodontal disease and smoking, alcohol consumption, diabetes and cardiovascular disease.

Periodontal CD14 mRNA expression is downregulated in patients with chronic periodontitis and type 2 diabetes

Background

Patients with type 2 diabetes mellitus (T2DM) have increased severity of periodontitis. Toll-like receptor (TLR)4, its co-receptors CD14 and MD-2, and adaptor MyD88 play pivotal roles in lipopolysaccharide (LPS)-triggered tissue inflammation and periodontitis. This study investigated the effects of T2DM and periodontitis on TLR4, CD14, MD-2 and MyD88 mRNA expression in surgically removed periodontal tissues.

Methods

Periodontal tissue specimens were collected from 14 patients without periodontitis and T2DM (Group 1), 15 patients with periodontitis alone (Group 2), and 7 patients with both periodontitis and T2DM (Group 3). The mRNA of TLR4, CD14, MD-2 and MyD88 was quantified using real-time PCR and compared between the groups.

Results

Statistical analysis showed that periodontal expression of CD14 mRNA was significantly reduced across Groups 1, 2 and 3 (p = 0.02) whereas the mRNA expression of TLR4, MD-2 and MyD88 was not significantly different among the groups. Furthermore, when patients in Groups 1 and 2 were combined (n = 22), the CD14 mRNA expression was significantly lower than that in patients of Group 1 (p = 0.04).

Conclusions

CD14 mRNA expression was downregulated across patients with neither periodontitis nor T2DM, patients with periodontitis alone and patients with both diseases, suggesting that CD14 mRNA expression is associated with a favorable host response or subjected to a negative feedback regulation.

Follicular dendritic cell-secreted protein may enhance osteoclastogenesis in periodontal disease

PURPOSE OF THE STUDY

Follicular dendritic cell-secreted protein (FDC-SP) has been found to be expressed in periodontal ligament (PDL), a layer of soft connective tissue between tooth root and alveolar bone, and involved in immunoreaction. This study was performed to explore the potential role of FDC-SP in periodontal disease.

MATERIALS AND METHODS

The human periodontal ligament cells (hPDLCs) were stimulated with Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) and FDC-SP expression was examined by real-time PCR and western blot. Then this molecule was overexpressed or silenced in hPDLCs by transfection of FDC-SP expression plasmids or its small-interfering (si) RNA, respectively, and the effects of FDC-SP on expression of osteogenesis- and osteoclastogenesis-related genes in hPDLCs were analyzed by real-time PCR and western blot.

RESULTS

Our results showed that P. gingivalis LPS upregulated FDC-SP expression in hPDLCs. Overexpression of FDC-SP could decrease the expression of osteogenesis-related genes, increase the expression of osteoclastogenesis-related genes and RANKL/OPG ratio in hPDLCs. Meanwhile, silence of FDC-SP expression in hPDLCs remarkably inversed the above results.

CONCLUSIONS

LPS-induced upregulation of FDC-SP expression in hPDLCs may enhance osteoclastogenesis in periodontal disease.

Gingival fibroblasts resist apoptosis in response to oxidative stress in a model of periodontal diseases

Periodontal diseases are classified as inflammation affecting the supporting tissue of teeth, which eventually leads to tooth loss. Mild reversible gingivitis and severe irreversible periodontitis are the most common periodontal diseases. Periodontal pathogens initiate the diseases. The bacterial toxin, lipopolysaccharide (LPS), triggers the inflammatory response and leads to oxidative stress. However, the progress of oxidative stress in periodontal diseases is unknown. The purpose of this study is to examine oxidative stress and cell damage in gingivitis and periodontitis. Our results showed that LPS increases reactive oxygen species (ROS) accumulation in gingival fibroblast (GF). However, oxidative stress resulting from excessive ROS did not influence DNA damage and cell apoptosis within 24 h. The mechanism may be related to the increased expression of DNA repair genes, Ogg1, Neil1 and Rad50. Detection of apoptosis-related proteins also showed anti-apoptotic effects and pro-apoptotic effects were balanced. The earliest damage appeared in DNA when increased γH2AX, an early biomarker for DNA damage, was detected in the LPS group after 48 h. Later, when recurrent inflammation persisted, 8-OHdG, a biomarker for oxidative stress was much higher in periodontitis model compared to the control in vivo. Staining of 8-OHdG in human periodontitis specimens confirmed the results. Furthermore, TUNEL staining of apoptotic cells indicated that the periodontitis model induced more cell apoptosis in gingival tissue. This suggested GF could resist early and acute inflammation (gingivitis), which was regarded as reversible, but recurrent and chronic inflammation (periodontitis) led to permanent cell damage and death.

Involvement of an Skp-Like Protein, PGN_0300, in the Type IX Secretion System of Porphyromonas gingivalis

The oral Gram-negative anaerobic bacterium Porphyromonas gingivalis is an important pathogen involved in chronic periodontitis. Among its virulence factors, the major extracellular proteinases, Arg-gingipain and Lys-gingipain, are of interest given their abilities to degrade host proteins and process other virulence factors. Gingipains possess C-terminal domains (CTDs) and are translocated to the cell surface or into the extracellular milieu by the type IX secretion system (T9SS). Gingipains contribute to the colonial pigmentation of the bacterium on blood agar. In this study, Omp17, the PGN_0300 gene product, was found in the outer membrane fraction. A mutant lacking Omp17 did not show pigmentation on blood agar and showed reduced proteolytic activity of the gingipains. CTD-containing proteins were released from bacterial cells without cleavage of the CTDs in the omp17 mutant. Although synthesis of the anionic polysaccharide (A-LPS) was not affected in the omp17 mutant, the processing of and A-LPS modification of CTD-containing proteins was defective. PorU, a C-terminal signal peptidase that cleaves the CTDs of other CTD-containing proteins, was not detected in any membrane fraction of the omp17 mutant, suggesting that the defective maturation of CTD-containing proteins by impairment of Omp17 is partly due to loss of function of PorU. In the mouse subcutaneous infection experiment, the omp17 mutant was less virulent than the wild type. These results suggested that Omp17 is involved in P. gingivalis virulence.

Biology and pathogenesis of cytomegalovirus in periodontal disease

Human periodontitis is associated with a wide range of bacteria and viruses and with complex innate and adaptive immune responses. Porphyromonas gingivalis, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, Treponema denticola, cytomegalovirus and other herpesviruses are major suspected pathogens of periodontitis, and a combined herpesvirus–bacterial periodontal infection can potentially explain major clinical features of the disease. Cytomegalovirus infects periodontal macrophages and T‐cells and elicits a release of interleukin‐1β and tumor necrosis factor‐α. These proinflammatory cytokines play an important role in the host defense against the virus, but they also have the potential to induce alveolar bone resorption and loss of periodontal ligament. Gingival fibroblasts infected with cytomegalovirus also exhibit diminished collagen production and release of an increased level of matrix metalloproteinases. This article reviews innate and adaptive immunity to cytomegalovirus and suggests that immune responses towards cytomegalovirus can play roles in controlling, as well as in exacerbating, destructive periodontal disease.