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

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL RELEVANCE

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

Relationship between periodontal destruction and gene mutations in patients with familial Mediterranean fever

Recent studies have shown that genetic factors involved in the host responses might determine the disease severity for both familial Mediterranean fever (FMF) and periodontitis. The present study aimed to investigate the relationship of FMF with periodontitis and to search for the potential association between periodontitis and MEFV gene missense variations in patients with FMF. The study consisted of 97 FMF patients and 34 healthy volunteers. FMF patients were classified according to the kind of MEFV gene mutation: (1) patients with homozygous M694V gene mutation, (2) patients with heterozygous M694V gene mutation, and (3) patients with MEFV gene different mutations. Gingival Index (GI), Plaque Index (PI), probing pocket depth (PD), and clinical attachment level (CAL) were measured in all participants. The results of multivariate logistic regression showed a highly significant association between homozygous M694V gene mutation and periodontitis in FMF patients (p < 0.05). After adjusting for potential confounders (smoking, body weight, age, and gender), FMF patients with homozygous M694V gene mutation were 3.51 (1.08-11.45) times more likely to present periodontitis than the other FMF patients. These results indicate that the presence of homozygous M694V gene mutation seems to increase the risk for periodontitis in FMF patients.

Detection and diagnosis of periodontal conditions amenable to prevention

Gingivitis and chronic periodontitis are highly prevalent chronic inflammatory diseases. Gingivitis affects the majority of people, and advanced periodontitis is estimated to affect 5-15% of adults. The detection and diagnosis of these common diseases is a fundamentally important component of oral health care. All patients should undergo periodontal assessment as part of routine oral examination. Periodontal screening using methods such as the Basic Periodontal Examination/Community Periodontal Index or Periodontal Screening Record should be performed for all new patients, and also on a regular basis as part of ongoing oral health care. If periodontitis is identified, full periodontal assessment is required, involving recording of full mouth probing and bleeding data, together with assessment of other relevant parameters such as plaque levels, furcation involvement, recession and tooth mobility. Radiographic assessment of alveolar bone levels is driven by the clinical situation, and is required to assess bone destruction in patients with periodontitis. Risk assessment (such as assessing diabetes status and smoking) and risk management (such as promoting smoking cessation) should form a central component of periodontal therapy. This article provides guidance to the oral health care team regarding methods and frequencies of appropriate clinical and radiographic examinations to assess periodontal status, to enable appropriate detection and diagnosis of periodontal conditions.

Evaluation of MicroRNA-146a and Its Targets in Gingival Tissues of Patients With Chronic Periodontitis

BACKGROUND

MicroRNAs (miRNAs) are a group of small non-coding RNAs that play an important role in the regulation of gene expression. miRNA-146a (miR-146a), a member of the miR-146 family, is involved in the control of inflammation. Periodontitis is a set of chronic inflammatory disorders of the tissues surrounding the teeth that lead to the breakdown of alveolar bone and tooth loss. In this study, expression levels of miR-146a and its targets, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, are evaluated in human patients with chronic periodontitis (CP).

METHODS

The study population consisted of 10 healthy controls and 20 individuals with CP. For each participant, clinical parameters including probing depth and clinical attachment level were measured, and a gingival tissue sample was collected. Levels of miR-146a, TNF-α, IL-1β, and IL-6 were quantified using real-time polymerase chain reaction.

RESULTS

Levels of miR-146a were significantly higher in patients with CP (P <0.001). There was a positive correlation between levels of miR-146a and clinical parameters (P <0.05). Elevated miR-146a was accompanied by a significant reduction in TNF-α and IL-6 (P <0.001).

CONCLUSIONS

Patients with CP had higher levels of miR-146a than healthy individuals, accompanied by reduced levels of TNF-α and IL-6. A positive relationship between miR-146a levels and clinical parameters suggests a pathophysiologic role of miR-146a in CP.

Demethylation of IGFBP5 by Histone Demethylase KDM6B Promotes Mesenchymal Stem Cell-Mediated Periodontal Tissue Regeneration by Enhancing Osteogenic Differentiation and Anti-Inflammation Potentials

Mesenchymal stem cell (MSC)-mediated periodontal tissue regeneration is considered a promising method for periodontitis treatment. The molecular mechanism underlying directed differentiation and anti-inflammatory actions remains unclear, thus limiting potential MSC application. We previously found that insulin-like growth factor binding protein 5 (IGFBP5) is highly expressed in dental tissue-derived MSCs compared with in non-dental tissue-derived MSCs. IGFBP5 is mainly involved in regulating biological activity of insulin-like growth factors, and its functions in human MSCs and tissue regeneration are unclear. In this study, we performed gain- and loss-of-function assays to test whether IGFBP5 could regulate the osteogenic differentiation and anti-inflammatory potential in MSCs. We found that IGFBP5 expression was upregulated upon osteogenic induction, and that IGFBP5 enhanced osteogenic differentiation in MSCs. We further showed that IGFBP5 prompted the anti-inflammation effect of MSCs via negative regulation of NFκB signaling. Depletion of the histone demethylase lysine (K)-specific demethylase 6B (KDM6B) downregulated IGFBP5 expression by increasing histone K27 methylation in the IGFBP5 promoter. Moreover, IGFBP5 expression in periodontal tissues was downregulated in individuals with periodontitis compared with in healthy people, and IGFBP5 enhanced MSC-mediated periodontal tissue regeneration and alleviated local inflammation in a swine model of periodontitis. In conclusion, our present results reveal a new function for IGFBP5, provide insight into the mechanism underlying the directed differentiation and anti-inflammation capacities of MSCs, and identify a potential target mediator for improving tissue regeneration. Stem Cells  2015;33:2523–2536

Association of lipid profile test values, type-2 diabetes mellitus, and periodontitis

Objective:

A two-way relationship between diabetes and periodontal disease has been suggested; whereas obesity and impaired lipid profile are risk factors for type-2 diabetes mellitus. This study examined the relationship between lipid profile, oral glucose tolerance test (OGTT) with periodontal health/disease dependent variables in healthy, diabetic and impaired glucose tolerance subjects.

Materials and Methods:

120 patients were selected for the study and were determined to be periodontally healthy or diseased. All these patients underwent biochemical tests for OGTT and Lipid profile analysis and data was compared using Z-test.

Results:

The OGTT results deteriorated with deteriorating periodontal condition. A similar correlation was also observed between worsening lipid profile test values, OGTT score, and periodontal condition.

Conclusion:

This study indicates that hyperlipidemia may be one of the factors associated with periodontitis and that periodontitis may itself lead to abnormal serum lipid levels. Therefore, in addition to effects on diabetes, periodontitis may contribute to elevated serum lipid levels and therefore potentially to systemic disease arising from chronic hyperlipidemia.

Levels of lipocalin-2 in crevicular fluid and tear fluid in chronic periodontitis and obesity subjects

AIM

Lipocalin-2, a 25 kDa secretory glycoprotein, was first found in the neutrophilic granules of humans and in mouse kidney cells. It has been shown to have an important role in inflammation. The aim of this study was to determine the levels of lipocalin-2 in gingival crevicular fluid and tear fluid in patients with obesity and chronic periodontitis.

METHODS

A total of 40 subjects in the age group 25-40 years were divided into four groups based on probing depth, gingival index, clinical attachment level, body mass index, and radiographic evidence of bone loss. The groups were: nonobese healthy group; obese healthy group; nonobese chronic periodontitis group; obese chronic periodontitis group Gingival crevicular fluid and tear fluid samples were collected on the subsequent day.

RESULTS

There was an increase in lipocalin-2 levels from group 1 to group 4 (with the nonobese healthy group showing the least levels and obese chronic periodontitis group showing the highest levels) in both gingival crevicular fluid and tear fluid.

CONCLUSION

Lipocalin-2 may be an important inflammatory marker that may help link obesity and chronic periodontitis.

Effects of oestrogen deficiency on the alveolar bone of rats with experimental periodontitis

Periodontitis is an inflammatory disease characterized by loss of connective tissue and alveolar bone, and osteoporosis is a common disease characterized by a systemic impairment of bone mass and microarchitecture. To date, the association between periodontitis and osteoporosis has remained to be fully elucidated. In the present study, an experimental rat model of periodontitis was used to explore the effects of oestrogen deficiency-induced osteoporosis on the maxillary alveolar bone. Forty-four female, six-month-old Sprague-Dawley rats were randomly divided into four groups: Control, ligature, ovariectomized (OVX), and OVX + ligature. One month after ovariectomy, rats in the ligature and OVX + ligature groups received ligatures on their first and second maxillary molars for 1 month. Fluorescent labelling was performed prior to sacrificing the animals. At the end of the experiment, the maxillae and serum were collected and subjected to micro-computed tomography analysis, confocal laser-scanning microscopic observation, Van Gieson's fuchsin staining, tartrate-resistant acid phosphatase staining and ELISA. Ligatures slightly reduced the alveolar bone mineral density (BMD) and bone formation rate, but significantly reduced alveolar crest height (ACH). Ovariectomy reduced the alveolar BMD, impaired the trabecular structure, reduced the bone formation rate and increased the serum levels of bone resorption markers. Animals in the OVX + ligature group exhibited a lower alveolar BMD, a poorer trabecular structure, a reduced ACH, a lower bone formation rate and higher serum levels of bone resorption markers compared with those in the control group. The results of the present study showed that ovariectomy enhanced alveolar bone loss and reduced the ACH of rats with experimental periodontitis. Thus, post-menopausal osteoporosis may influence the progression of periodontitis.

Class I and II histone deacetylase expression in human chronic periodontitis gingival tissue

BACKGROUND AND OBJECTIVE

Histone deacetylase inhibitors (HDACi) are being considered to treat chronic inflammatory diseases at low doses. Currently HDACi that are more specific are being developed to target particular HDACs; therefore, this study aimed to determine levels and distribution of class I and II HDAC in human gingival samples obtained from patients with chronic periodontitis.

MATERIAL AND METHODS

Gingival biopsies were obtained from patients with and without (mild inflammation, no bone loss) periodontitis. Total RNA was isolated for real-time quantitative polymerase chain reaction to determine expression of HDACs 1-10. Immunohistochemistry was used to determine protein distribution of HDACs 1, 5, 8 and 9. Factor VIII, CD3 and tartrate resistant acid phosphatase (TRAP) were detected in serial sections to identify blood vessels, lymphocytes, pre-osteoclasts and osteoclasts cells respectively. Tumour necrosis factor α (TNF-α) expression was also assessed.

RESULTS

mRNA for HDAC 1, 5, 8 and 9 were significantly upregulated in chronic periodontitis gingival tissues compared to non-periodontitis samples (p < 0.05). Significantly higher HDAC 1 protein expression was observed in chronic periodontitis samples (p < 0.05), and was associated with CD3, TRAP and TNF-α-positive cells. HDAC 1, 5, 8 and 9 were expressed strongly by the factor VIII-positive microvasculature in the chronic periodontitis gingival tissues.

CONCLUSIONS

HDAC 1, 5, 8 and 9 expression was higher in gingival tissues from patients with chronic periodontitis compared to non-periodontitis samples. Results suggest that these HDACs could therefore be targeted with specific acting HDACi.

Clinical, microbiological, and immunological aspects of healthy versus peri-implantitis tissue in full arch reconstruction patients: a prospective cross-sectional study

Background

Due to the world-wide increase in treatments involving implant placement, the incidence of peri-implant disease is increasing. Late implant failure is the result of the inability to maintain osseointegration, whose most important cause is peri-implantitis. The aim of this study was to analyze the clinical, microbiological, and immunological aspects in the peri-implant sulcus fluid (PISF) of patients with healthy dental implants and patients with peri-implantitis.

Methods

PISF samples were obtained from 24 peri-implantitis sites and 54 healthy peri-implant sites in this prospective cross-sectional study. The clinical parameters recorded were: modified gingival index (mGI), modified plaque index (mPI) and probing pocket depth (PPD). The periodontopathogenic bacteria Tannerella forsythia, Treponema denticola and Porphyromonas gingivalis were evaluated, together with the total bacterial load (TBL). PISF samples were analyzed for the quantification of Interleukin (IL)-8, IL-1β, IL-6, IL-10 and Tumor Necrosis Factor (TNF)-α using flow cytometry (FACS).

Results

The mGI and PPD scores in the peri-implantitis group were significantly higher than the healthy group (p < 0.001). A total of 61.5% of the patients with peri-implantitis had both arches rehabilitated, compared with 22.7% of patients with healthy peri-implant tissues; there was no implant with peri-implantitis in cases that received mandibular treatment exclusively (p < 0.05). Concentrations of Porphyromonas gingivalis (p < 0.01), association with bacteria Porphyromonas gingivalis and Treponema denticola (p < 0.05), as well as the TBL (p < 0.05) are significantly higher in the peri-implantitis group. IL-1β (p < 0.01), IL-6 (p < 0.01), IL-10 (p < 0.05) and TNF-α (p < 0.01) are significantly higher at the sites with peri-implantitis compared to healthy peri-implant tissue, while IL-8 did not increase significantly.

Conclusion

The results of the present study involving a limited patient sample suggest that the peri-implant microbiota and which dental arch was rehabilitated involved could contribute to bone loss in peri-implantitis. A significant relationship is observed between the concentration of cytokines (interleukins 1β, 6 and 10 and TNF-α) and the inflammatory response in peri-implantitis tissue.

Effects of electroacupuncture on experimental periodontitis in rats

BACKGROUND

Acupuncture has shown the capability of modulating the immuno-inflammatory response of the host. This study aims to evaluate the effects of electroacupuncture (EA) on ligature-induced periodontitis in rats.

METHODS

Thirty-two animals were divided into four groups: 1) control; 2) experimental periodontitis (EP); 3) sham-treated (EP/EA-sham); and 4) treated with EA (EP/EA). For the EP groups, a ligature was placed around the right mandibular first molars at day 1. Sessions of EA or EA-sham were assigned every other day. For EA treatment, large intestine meridian points LI4 and LI11 and stomach meridian points ST36 and ST44 were used. EA-sham was performed in off-meridian points. Animals were euthanized at day 11. Histomorphometric and microtomographic analyses were performed. Immunolabeling patterns for the receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), and tartrate-resistant acid phosphatase (TRAP) were assessed. Expressions of interleukin (IL)-1β, matrix metalloproteinase (MMP)-8, IL-6, and cyclooxygenase (COX)-2 messenger RNAs (mRNAs) were evaluated by quantitative reverse transcription-polymerase chain reaction. Data were analyzed statistically (P <0.05, analysis of variance).

RESULTS

Histomorphometric and microtomographic analyses demonstrated that group EP/EA presented reduced alveolar bone loss when compared to group EP (P <0.05). Reduced RANKL immunolabeling and fewer TRAP-positive multinucleated cells were observed in the EA-treated group in relation to group EP. No differences were observed in OPG expression among groups. EA treatment decreased the genic expression of IL-1β and MMP-8 (P <0.05), increased the mRNA expression of IL-6 (P <0.05), and did not modify the genic expression of COX-2 in animals with EP (P >0.05).

CONCLUSION

It can be concluded that EA reduced periodontal tissue breakdown and the expression of some proinflammatory mediators and a proresorptive factor in EP in rats.

Significance of circulating and crevicular matrix metalloproteinase-9 in rheumatoid arthritis-chronic periodontitis association

In the recent years, statistically significant associations between rheumatoid arthritis (RA) and periodontal disease have been identified. Emerging as a chronic inflammatory joint disease, RA displays various features and pathogenetic events similar to chronic periodontitis (CP). The purpose of this study was to evaluate the utility of determining systemic and crevicular levels of metalloproteinase-9 (MMP-9) as potential biomarkers for association between RA and CP. A total of fifty-six patients were included in the study. The subjects were categorized into four groups as follows: healthy-control (n = 21), active RA (n = 16), CP (n = 14), and RA-CP association (n = 12). Assessment of serum and crevicular concentrations of total MMP-9 (active and pro-MMP-9) was based on ELISA technique. The results of this study showed statistically significant differences of serum MMP-9 between patients groups and control. Serum levels of MMP-9 were similar in RA and RA-CP associated patients. Gingival crevicular fluid (GCF) recorded increased MMP-9 levels in RA-CP association subjects as compared to CP. Considering that RA-CP association is characterized by a disregulation of the inflammatory response, MMP-9 may play a role in the pathogenesis of RA-CP association. MMP-9 is therefore a sensitive tool in the diagnosis and management of patients affected by this binomial association.

Evaluation of biochemical parameters and local and systemic levels of osteoactive and B-cell stimulatory factors in gestational diabetes in the presence or absence of gingivitis

BACKGROUND

Gestational diabetes mellitus (GDM) is defined as varying glucose intolerance, with first onset or recognition in pregnancy. This study evaluates clinical and biochemical parameters in a possible association between GDM and gingivitis.

METHODS

A total of 167 pregnant females was included in the study. There were 101 females with GDM and 66 females without GDM. Subgroups were created according to the presence or absence of gingival inflammation. Plaque index, bleeding on probing, and probing depth were recorded at four sites per tooth. Serum, saliva, and gingival crevicular fluid (GCF) levels of interleukin (IL)-6, IL-8, soluble receptor activator of nuclear factor-kappa B ligand (sRANKL), osteoprotegerin (OPG), B-cell activating factor (BAFF), and a proliferation-inducing ligand (APRIL) were determined by enzyme-linked immunosorbent assay. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests and Spearman correlation analysis.

RESULTS

Age and anthropometric indices were higher in the GDM than non-GDM group (P <0.0001). Clinical periodontal recordings, serum BAFF, IL-8, and saliva sRANKL levels were higher in the GDM group (P <0.05). Saliva IL-6 level was higher in the GDM with gingivitis group than non-GDM with gingivitis group (P = 0.044). Serum and GCF BAFF (P <0.0001), serum, saliva, and GCF APRIL (P <0.0001; P <0.0001; P = 0.032, respectively), GCF OPG (P = 0.036), and serum and saliva sRANKL (P <0.0001) were higher in the GDM with gingivitis group than GDM without gingivitis group.

CONCLUSIONS

The inflammatory response seems to be more pronounced in females with GDM. The observed increase in both local and systemic levels of inflammatory cytokines may suggest an interaction between gingivitis and GDM.

Role of resistin in the inflammatory response induced by nicotine plus lipopolysaccharide in human periodontal ligament cells in vitro

BACKGROUND AND OBJECTIVE

Resistin was recently reported to play a role in inflammation-related diseases such as arthritis. However, the precise role of resistin in chronic inflammatory diseases, such as periodontal disease, remains unclear. The aim of this study was to investigate the combined effects of nicotine and lipopolysaccharide (LPS) on the expression of resistin and to assess whether resistin expression influences the levels of inflammatory cytokines, extracellular matrix (ECM) molecules and MMPs in human periodontal ligament cells (PDLCs) stimulated with both nicotine and LPS.

MATERIAL AND METHODS

PDLCs were pretreated with isoproterenol or resistin-specific small interfering RNA (siRNA), stimulated with LPS plus nicotine for 24 h, and then monitored for the production of inflammatory mediators. The concentrations of prostaglandin E2 (PGE2) and nitric oxide (NO) were measured by radioimmunoassay and the Griess method, respectively. RT-PCR and western blot analysis were used to measure the levels of mRNA and protein, respectively. Western blot analysis was also used to assess the activation of various signal-transduction pathways.

RESULTS

Treatment with nicotine plus LPS up-regulated the expression of resistin mRNA and the production of resistin protein in PDLCs in a time- and concentration-dependent manner. Isoproterenol-mediated interference with the function of resistin, or siRNA-mediated knockdown of resistin expression, markedly attenuated the LPS plus nicotine-mediated stimulation of PGE2 and NO production, the production of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase proteins and the expression of proinflammatory cytokines [tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-12] and MMPs (MMP-1, MMP-2 and MMP-9); however, these treatments restored the expression of ECM molecules. Furthermore, pretreatment with isoproterenol or resistin-specific siRNA blocked nicotine plus LPS-induced activation of phosphoinositide-3-kinase, glycogen synthase kinase-3 beta, β-catenin, p38, ERK, JNK and nuclear factor-κB.

CONCLUSION

This is the first study to show that the inhibition of resistin, by either a pharmacological or a genetic silencing approach, has anti-inflammatory effects. These effects include decreased levels of inflammatory cytokines and the prevention of ECM breakdown in a nicotine plus LPS-stimulated PDLC model.

Transfection with follicular dendritic cell secreted protein to affect phenotype expression of human periodontal ligament cells

Follicular dendritic cell secreted protein (FDC-SP), has been found to inhibit osteogenic differentiation of human periodontal ligament cells (hPDLCs) in recent studies. Based on these findings, we further investigate its effect on phenotype expression of hPDLCs in the present study, aiming to contribute to a better understanding of the biological functions governing FDC-SP-induced hPDLC differentiation. hPDLCs were firstly identified with immunocytochemical staining, followed by transfection with FDC-SP lentiviral vector. Western blot analysis was used to confirm the expression of FDC-SP. Then the influence of FDC-SP transfection on hPDLC proliferation, osteogenic and fibrogenic phenotype expression was evaluated at the mRNA and protein level. Procollagen type I c-peptide production was measured and alizarin red staining was then conducted to demonstrate effect of FDC-SP on functional differentiation. We found that hPDLCs could be successfully transfected with FDC-SP. Cell proliferation and cell cycle tests indicated that transfection with FDC-SP did not affect hPDLC proliferation. Moreover, according to real-time PCR and Western blot results, expression levels of type 1 collagen alpha 1, type 1 collagen alpha 2 and type 3 collagen were upregulated while that of osteocalcin, osteopontin, and bone sialoprotein were downregulated in FDC-SP transfected cells. In addition, hPDLCs overexpressing FDC-SP exhibited higher PIP production than the controls. Our findings demonstrate that transfection with FDC-SP has negligible adverse effect on proliferation of hPDLCs and imply the biological function of FDC-SP as a fibroblastic phenotype stabilizer by inhibiting hPDLCs differentiation into mineralized tissue-forming cells, thus regulating regeneration in periodontal tissue engineering.

Evaluation of the efficacy of 2% curcumin gel in the treatment of experimental periodontitis

CONTEXT

Local drug delivery (LDD) systems have been proposed for the treatment of periodontitis. Curcumin could be a suitable agent as LDD for the treatment of periodontitis.

AIM

To formulate, evaluate the anti-inflammatory activity and to assess the duration of the action and the efficacy of 2% curcumin gel in the treatment of experimental periodontitis in Wistar albino rat model.

SETTINGS AND DESIGN

Twenty-one Wistar albino rats were randomly assigned to three groups. Periodontitis was induced using ligature model. Group 1: Control; group 2: Plain gel, and group 3: 2% curcumin gel.

MATERIALS AND METHODS

About 2% curcumin gel was prepared. The anti-inflammatory activity and duration of action was assessed. Silk ligature 5-0 was used to induce periodontitis. Gingival index (GI) and probing pocket depth (PPD) were measured. Treatment was done. The rats were sacrificed. Morphometric analysis was performed using stereomicroscope and ImageJ software.

STATISTICAL ANALYSIS USED

Analysis of variance followed by Bonferroni's test, Wilcoxon's test for inter-group comparison, Mann-Whitney test for P value computation was used. The observations are mean ± standard deviation and standard error of the mean. P < 0.01 when compared to control was considered as statistically significant.

RESULTS

About 2% curcumin gel showed 42.98% inhibition of edema and peak activity was noted at 24 h. There was statistically significant change in the GI and PPD. Morphometric analysis did not show any significant difference between groups. No toxic effects were seen on oral administration of 2000 mg/kg of curcumin.

CONCLUSIONS

About 2% curcumin gel was effective in the treatment of experimental periodontitis.

Epigenetic changes of TIMP-3, GSTP-1 and 14-3-3 sigma genes as indication of status of chronic inflammation and cancer

OBJECTIVES

This study aimed to compare the epigenetic changes via hypermethylation status of TIMP-3, GSTP-1 and 14-3-3σ genes, between healthy subjects and patients with reversible chronic inflammatory disease, and between healthy subjects and patients with irreversible malignant disease, to highlight the genetic changes that occur in the progression from an inflammatory condition to irreversible genetic changes commonly observed in cancer patients.

METHODS

DNA was extracted from the blood of 680 healthy subjects, and tissues and blood of 110 patients with chronic inflammation disease of the gums, as well as neoplastic tissues of 108 breast cancer patients. Methylation-specific polymerase chain reaction (PCR) for TIMP-3, GSTP-1 and 14-3-3σ was performed, and hypermethylation status was analyzed and compared between the 3 groups.

RESULTS

The hypermethylation frequencies of TIMP-3 and GSTP-1 of reversible chronic inflammatory gum disease and the control group were similar, but both were significantly lower than those for malignant disease patients (p<0.0001). The methylation frequency of 14-3-3σ in chronic inflammatory gum disease was higher than in the cancer and control groups (p<0.0001). The methylation of CpG islands in TIMP-3 and GSTP-1 in chronic inflammation patients occurred as frequently as in the control group, but less frequently than in breast cancer patients. However, the epigenetic silencing of 14-3-3σ occurred more frequently in the chronic inflammation group than in cancer patients and healthy controls.

CONCLUSIONS

The epigenetic silencing of 14-3-3σ might be essential for chronic inflammatory gum disease. The epigenetic changes presented in chronic inflammation patients might demonstrate an irreversible destruction in the tissues or organs similar to cancer.

NOD2 contributes to Porphyromonas gingivalis-induced bone resorption

The NOD-like receptors are cytoplasmic proteins that sense microbial by-products released by invasive bacteria. Although NOD1 and NOD2 are functionally expressed in cells from oral tissues and play a role triggering immune responses, the role of NOD2 receptor in the bone resorption and in the modulation of osteoclastogenesis is still unclear. We show that in an experimental model of periodontitis with Porphyromonas gingivalis W83, NOD2(-/-) mice showed lower bone resorption when compared to wild type. Quantitative polymerase chain reaction analysis revealed that wild-type infected mice showed an elevated RANKL/OPG ratio when compared to NOD2(-/-) infected mice. Moreover, the expression of 2 osteoclast activity markers-cathepsin K and matrix metalloproteinase 9-was significantly lower in gingival tissue from NOD2(-/-) infected mice compared to WT infected ones. The in vitro study reported an increase in the expression of the NOD2 receptor 24 hr after stimulation of hematopoietic bone marrow cells with M-CSF and RANKL. We also evaluated the effect of direct activation of NOD2 receptor on osteoclastogenesis, by the activation of this receptor in preosteoclasts culture, with different concentrations of muramyl dipeptide. The results show no difference in the number of TRAP-positive cells. Although it did not alter the osteoclasts differentiation, the activation of NOD2 receptor led to a significant increase of cathepsin K expression. We confirm that this enzyme was active, since the osteoclasts resorption capacity was enhanced by muramyl dipeptide stimulation, evaluated in osteoassay plate. These results show that the lack of NOD2 receptor impairs the bone resorption, suggesting that NOD2 receptor could contribute to the progression of bone resorption in experimental model of periodontitis. The stimulation of NOD2 by its agonist, muramyl dipeptide, did not affect osteoclastogenesis, but it does favor the bone resorption capacity identified by increased osteoclast activity.

Prevalence of human papilloma virus in marginal periodontium and its association with periodontitis: A cross sectional study

Context:

Bacterial pathogens in dental plaque are necessary for the development of periodontitis but this etiology alone does not explain all its clinicopathologic features. Researchers have proven the role of certain viruses like herpes virus in periodontal disease which implies that other viral agents like human papilloma virus may also be involved.

Aims:

This cross-sectional study was conducted to determine the proportion of patients with human papilloma virus (HPV-16) in marginal periodontium by analyzing DNA from the gingival tissue sample and to understand its association with periodontitis.

Settings and Design:

102 systemically healthy patients between the age group of 15 and 70 years reporting to the Department of Periodontology who required surgical intervention (flap surgery for patients with periodontitis and crown lengthening for healthy patients) with internal bevel gingivectomy were selected.

Materials and Methods:

After scaling and root planning, gingival tissue was collected during the respective surgical procedure. DNA was isolated and amplified using specific primers for HPV-16 by polymerase chain reaction (PCR). The amplified products were checked by agarose gel electrophoresis.

Results:

No HPV DNA was detected in the 102 samples analyzed.

Conclusion:

Marginal periodontium does not contain HPV in this study population and hence there was no association between HPV and periodontitis.

Effect of chronic stress on ligature-induced periodontitis in inbred and noninbred rats: a radiographic study

AIM

The aim was to compare the effect of chronic stress on ligature-induced periodontitis in inbred and noninbred female rats by means of a radiographic study.

MATERIALS AND METHODS

Adult Lewis (inbred) and Wistar (non-inbred) rats were used and divided into the following groups: Ligature/Stress Lewis Group (LSLG, n = 8); Ligature/Stress Wistar Group (LSWG, n = 8); Ligature Lewis Group (LLG, n = 8) and Ligature Wistar Group (LWG, n = 8). The animals were anesthetized and a silk thread was continuously kept around their second upper right molar. Then, groups LSLG and LSWG were subjected to physical stress test (physical restraint for 12 hours). After 15 days of ligature placement, the animals were euthanized. The right hemimaxilla was kept in formalin solution for 48 hours. Radiographs of the hemimaxillae were obtained using the parallelism technique and subsequently submitted to a standardized radiographic processing. The examiner was blinded to the groups and calibrated. The bone height level was measured and the data were subjected to statistical analysis (ANOVA, Tukey, p < 0.05).

RESULTS

LSWG showed bone destruction significantly higher than that of LSLG (32.1 ± 1.45 mm and 23.6 mm ± 2.13, respectively). Similarly, LWG showed bone destruction significantly higher than that of LLG (28.6 ± 1.18 mm and 25.2 ± 2.76 mm, respectively).

CONCLUSION

Inbred rats (Lewis) are less susceptible to the effects of chronic stress than are noninbred rats (Wistar) in relation to ligature-induced periodontitis.

CLINICAL SIGNIFICANCE

Epidemiological studies have shown a relationship between stress and periodontitis. One of the major difficulties of this type of research is the bias of the exact diagnosis of the patient's emotional state. Inbred lines animals have standards-specific neuroendocrine, this allows answers about the susceptibility of periodontal disease, making knowledge applicable in future clinical trials.

Obesity, diabetes and periodontitis--a triangular relationship?

The global rise of obesity, both adult and childhood, has been paralleled by a rise in type 2 diabetes, a trend predicted to continue for at least the next two decades. The combined effect will create a burden of direct and co-morbidities that will strain the physical and financial resources of all countries. While it is accepted that both type 1 and type 2 diabetes are major risk factors for the development and progression of periodontal disease, there is growing evidence that obesity is both an indirect risk factor because it affects glycaemic control and a direct risk factor because secretion of pro-inflammatory agents by adipose tissue modifies the periodontal reaction to the plaque biofilm. Recent research suggests that periodontitis may adversely affect glycaemic control, which can be improved by periodontal treatment with reduced risk of diabetic co-morbidity, thereby creating a two-way relationship. Furthermore it appears possible that periodontitis may stimulate inflammatory change in adipose tissue, creating a triangular self-generating cycle of morbidity linking obesity, diabetes and periodontal disease. Dentists should recognise these interlinked risk factors and consider including an assessment of glycaemic control and adiposity, possibly by waist-to-hip ratio, when periodontitis is diagnosed and in collaboration with medical practitioners provide treatment to help reduce the development of systemic disease.

Esthetic treatment of a periodontal patient with prefabricated composite veneers and fiber-reinforced composite: clinical considerations and technique

The advances in periodontal therapy and the clinical success of adhesive dentistry have changed the way dentists treat periodontal patients. As more teeth are saved, the demand for functional and esthetic restoration of periodontally involved teeth grows. Once, these teeth were restored with full-coverage splinted restorations, whereas today, adhesive techniques provide less invasive and less complicated treatment options. This paper presents a novel adhesive combination of fiber-reinforced composite and prefabricated composite veneers to restore function and esthetics in a periodontal patient with severe bone and attachment loss. After successful completion of the periodontal treatment, fiber-reinforced composite has been bonded to the buccal surface of the maxillary anterior teeth in order to control teeth mobility. At the same appointment, prefabricated composite veneers have been bonded to the splinted teeth in order to restore esthetics. The final result shows full integration of contemporary adhesive techniques for single-appointment, minimally invasive treatment of a periodontal patient.

CLINICAL SIGNIFICANCE

This paper describes the use of fiber-reinforced composite and prefabricated composite veneers for the treatment of severe periodontal patients with a minimally invasive, single-appointment technique.

Porphyromonas gingivalis peptidylarginine deiminase, a key contributor in the pathogenesis of experimental periodontal disease and experimental arthritis

OBJECTIVES

To investigate the suggested role of Porphyromonas gingivalis peptidylarginine deiminase (PAD) in the relationship between the aetiology of periodontal disease and experimentally induced arthritis and the possible association between these two conditions.

METHODS

A genetically modified PAD-deficient strain of P. gingivalis W50 was produced. The effect of this strain, compared to the wild type, in an established murine model for experimental periodontitis and experimental arthritis was assessed. Experimental periodontitis was induced following oral inoculation with the PAD-deficient and wild type strains of P. gingivalis. Experimental arthritis was induced via the collagen antibody induction process and was monitored by assessment of paw swelling and micro-CT analysis of the radio-carpal joints. Experimental periodontitis was monitored by micro CT scans of the mandible and histological assessment of the periodontal tissues around the mandibular molars. Serum levels of anti-citrullinated protein antibodies (ACPA) and P. gingivalis were assessed by ELISA.

RESULTS

The development of experimental periodontitis was significantly reduced in the presence of the PAD-deficient P. gingivalis strain. When experimental arthritis was induced in the presence of the PAD-deficient strain there was less paw swelling, less erosive bone damage to the joints and reduced serum ACPA levels when compared to the wild type P. gingivalis inoculated group.

CONCLUSION

This study has demonstrated that a PAD-deficient strain of P. gingivalis was associated with significantly reduced periodontal inflammation. In addition the extent of experimental arthritis was significantly reduced in animals exposed to prior induction of periodontal disease through oral inoculation of the PAD-deficient strain versus the wild type. This adds further evidence to the potential role for P. gingivalis and its PAD in the pathogenesis of periodontitis and exacerbation of arthritis. Further studies are now needed to elucidate the mechanisms which drive these processes.

Evaluation of the role of antibiotics in preventing postoperative complication after routine periodontal surgery: A comparative clinical study

Background and Objectives:

Aim of this randomly controlled clinical study was to evaluate the role of antibiotics to prevent postoperative complications after routine periodontal surgery and also to determine whether their administration improved the surgical outcome.

Materials and Methods:

Forty-five systemically healthy patients with moderate to severe chronic periodontitis requiring flap surgery were enrolled in the study. They were randomly allocated to Amoxicillin, Doxycycline, and control groups. Surgical procedures were carried out with complete asepsis as per the protocol. Postoperative assessment of patient variables like swelling, pain, temperature, infection, ulceration, necrosis, and trismus was performed at intervals of 24 h, 48 h, 1 week, and 3 months. Changes in clinical parameters such as gingival index, plaque index, probing pocket depth, and clinical attachment level were also recorded.

Results:

There was no incidence of postoperative infection in any of the patients. Patient variables were comparable in all the three groups. Though there was significant improvement in the periodontal parameters in all the groups, no statistically significant result was observed for any group over the others.

Conclusion:

Results of this study showed that when periodontal surgical procedures were performed following strict asepsis, the incidence of clinical infection was not significant among all the three groups, and also that antibiotic administration did not influence the outcome of surgery. Therefore, prophylactic antibiotics for patients who are otherwise healthy administered following routine periodontal surgery to prevent postoperative infection are unnecessary and have no demonstrable additional benefits.

Lessons learned and unlearned in periodontal microbiology

Periodontal diseases are initiated by bacterial species living in polymicrobial biofilms at or below the gingival margin and progress largely as a result of the inflammation elicited by specific subgingival species. In the past few decades, efforts to understand the periodontal microbiota have led to an exponential increase in information about biofilms associated with periodontal health and disease. In fact, the oral microbiota is one of the best-characterized microbiomes that colonize the human body. Despite this increased knowledge, one has to ask if our fundamental concepts of the etiology and pathogenesis of periodontal diseases have really changed. In this article we will review how our comprehension of the structure and function of the subgingival microbiota has evolved over the years in search of lessons learned and unlearned in periodontal microbiology. More specifically, this review focuses on: (i) how the data obtained through molecular techniques have impacted our knowledge of the etiology of periodontal infections; (ii) the potential role of viruses in the etiopathogenesis of periodontal diseases; (iii) how concepts of microbial ecology have expanded our understanding of host-microbe interactions that might lead to periodontal diseases; (iv) the role of inflammation in the pathogenesis of periodontal diseases; and (v) the impact of these evolving concepts on therapeutic and preventive strategies to periodontal infections. We will conclude by reviewing how novel systems-biology approaches promise to unravel new details of the pathogenesis of periodontal diseases and hopefully lead to a better understanding of their mechanisms.

Periodontitis: a host-mediated disruption of microbial homeostasis. Unlearning learned concepts

New concepts evolve when existing ones fail to address known factors adequately or are invalidated by new evidence. For decades periodontitis has been considered to be caused by specific bacteria or groups of bacteria and, accordingly, treatment protocols have largely been based on anti-infective therapies. However, close inspection of current data leads one to question whether these bacteria are the cause or the result of periodontitis. Good evidence is emerging to suggest that it is indeed the host response to oral bacteria that leads to the tissue changes noted in gingivitis. These changes lead to an altered subgingival environment that favors the emergence of 'periodontal pathogens' and the subsequent development of periodontitis if the genetic and external environmental conditions are favorable for disease development. Thus, it seems that it is indeed the initial early host-inflammatory and immune responses occurring during the development of gingivitis, and not specific bacteria or their so-called virulence factors, which determine whether periodontitis develops and progresses. In this review we consider these concepts and their potential to change the way in which we view and manage the inflammatory periodontal diseases.

Periodontal disease and dental caries among Indigenous Australians living in the Northern Territory, Australia

BACKGROUND

The aim of this study was to describe the caries experience and severity of periodontal disease in a convenience sample of Indigenous Australians living in the Northern Territory.

METHODS

Data were gathered via self-reported questionnaire and dental examination by calibrated examiners. Socio-demographic characteristics were compared with data from the 2011 Australian census while prevalence of periodontal disease and dental caries was compared against weighted estimates from the National Survey of Adult Oral Health 2004-2006. In each comparison, non-overlapping 95% confidence intervals inferred a significant difference. Within-study comparisons were assessed via chi-square, t-tests and analysis of variance for differences among study participants.

RESULTS

A total of 312 Indigenous Australian participants provided completed data (average age 39.5 ± 10.5 years, 174 males). Of these, 87.5% were confirmed periodontitis cases; 3.5 times that of national-level estimates. The experience of untreated caries was five times that of national estimates (mean decayed 3.0 versus 0.6). Periodontitis case status was positively associated with older age, male gender and presence of diabetes.

CONCLUSIONS

Periodontal disease and untreated caries were significantly more prevalent in this sample of Indigenous Australians compared to the general Australian population. The prevalence of periodontal disease was markedly higher than that previously described for Indigenous Australians.

Periodontal disease in Thai patients with rheumatoid arthritis

AIM

To evaluate the prevalence and severity of periodontal disease in patients with rheumatoid arthritis (RA) who attended a rheumatology clinic in a university hospital.

METHODS

All consecutive patients with RA who attended the rheumatology clinic between June 2009 and January 2010 were asked to enroll in this study. All participants answered questionnaires, which included demographic data, medical history, medications used and smoking habits. A full mouth periodontal examination, including gingival index, plaque index, probing pocket depth and clinical attachment level was performed. Only cases that had at least 20 teeth were included in this study. Rheumatoid arthritis parameters, including number of tender and swollen joints, erythrocyte sedimentation rate, the presence of rheumatoid factor (RF), hand radiographs, Disease Activity Index (DAS) and health status using the Thai Health Assessment Questionnaire (HAQ), were determined. The association between RA parameters and periodontal condition was examined.

RESULTS

There were 196 participants (87.2% female) with a mean age of 51.7 ± 9.70 years, mean disease duration of 9.62 ± 7.0 years and mean DAS score of 4.64 ± 1.25. Eighty-two per cent were RF-positive. Moderate and severe periodontitis were found in 42% and 57%, respectively. Higher age, male gender, previous or current smoking and high level of plaque score were associated with severe periodontal disease. No differences in RA parameters were found between groups of patients who had moderate and severe periodontitis.

CONCLUSIONS

We found a high prevalence of periodontitis in Thai patients with RA. However, there was no association between RA parameters and periodontal conditions.

Genetic dysbiosis: the role of microbial insults in chronic inflammatory diseases

Thousands of bacterial phylotypes colonise the human body and the host response to this bacterial challenge greatly influences our state of health or disease. The concept of infectogenomics highlights the importance of host genetic factors in determining the composition of human microbial biofilms and the response to this microbial challenge. We hereby introduce the term ‘genetic dysbiosis’ to highlight the role of human genetic variants affecting microbial recognition and host response in creating an environment conducive to changes in the normal microbiota. Such changes can, in turn, predispose to, and influence, diseases such as: cancer, inflammatory bowel disease, rheumatoid arthritis, psoriasis, bacterial vaginosis and periodontitis. This review presents the state of the evidence on host genetic factors affecting dysbiosis and microbial misrecognition (i.e. an aberrant response to the normal microbiota) and highlights the need for further research in this area.

Longitudinal supportive periodontal therapy for severe chronic periodontitis with furcation involvement: a 12-year follow-up report

We report a case involving a 12-year follow-up after treatment for chronic periodontitis with furcation involvement. A 54-year-old woman presented with the chief complaint of hypersensitivity. Clinical examination at the first visit revealed 15% of sites with a probing depth ≥4 mm and 35% of sites with bleeding on probing. Initial periodontal therapy was implemented based on a clinical diagnosis of severe chronic periodontitis. Surgical periodontal therapy was subsequently performed at selected sites. For #44, regenerative periodontal therapy using enamel matrix derivative (Emdogain(®)) was selected. For #16, which exhibited a 2- to 3-wall vertical bony defect and class III (mesio-distal) furcation involvement, bone graft was scheduled. Other sites with residual periodontal pockets were treated by open flap debridement. For #37, with a gutter-shaped root, odontoplasty was performed. After reevaluation, the patient was placed on supportive periodontal therapy (SPT). During 12 years of SPT, the periodontal condition remained uneventful in most of the teeth. However, bone resorption was observed in the distal aspect of #37, making the prognosis poor. This indicates the need to continuously monitor risk factors, including inflammation and traumatic occlusion, during SPT. Although some problems still remain, severe periodontitis with furcation involvement was successfully maintained longitudinally with an adequate level of patient compliance and careful SPT.

Determination of nitrite in saliva using microfluidic paper-based analytical devices

Point-of-care platforms can provide fast responses, decrease the overall cost of the treatment, allow for in-home determinations with or without a trained specialist, and improve the success of the treatment. This is especially true for microfluidic paper-based analytical devices (μPAD), which can enable the development of highly efficient and versatile analytical tools with applications in a variety of biomedical fields. The objective of this work was the development of μPADs to identify and quantify levels of nitrite in saliva, which has been proposed as a potential marker of periodontitis. The devices were fabricated by wax printing and allowed the detection of nitrite by a colorimetric reaction based on a modified version of the Griess reaction. The presented modifications, along with the implementation of a paper-based platform, address many of the common drawbacks (color development, stability, etc.) associated with the Griess reaction and are supported by results related to the design, characterization, and application of the proposed devices. Under the optimized conditions, the proposed devices enable the determination of nitrite in the 10-1000 μmol L(-1) range with a limit of detection of 10 μmol L(-1) and a sensitivity of 47.5 AU [log (μmol L(-1))](-1). In order to demonstrate the potential impact of this technology in the healthcare industry, the devices were applied to the analysis of a series of real samples, covering the relevant clinical range.