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1.  Inflammation and Uncoupling as Mechanisms of Periodontal Bone Loss 
Journal of Dental Research  2011;90(2):143-153.
Periodontal disease is characterized by both inflammation and bone loss. Advances in research in both these areas have led to a new appreciation of not only each field but also the intimate relationship between inflammation and bone loss. This relationship has resulted in a new field of science called osteoimmunology and provides a context for better understanding the pathogenesis of periodontal disease. In this review, we discuss several aspects of the immuno-inflammatory host response that ultimately results in loss of alveolar bone. A proposal is made that periodontal inflammation not only stimulates osteoclastogenesis but also interferes with the uncoupling of bone formation and bone resorption, consistent with a pathologic process. Furthermore, arguments based on experimental animal models suggest a critical role of the spatial and temporal aspects of inflammation in the periodontium. A review of these findings leads to a new paradigm to help explain more fully the impact of inflammation on alveolar bone in periodontal disease so that it includes the effects of inflammation on uncoupling of bone formation from resorption.
doi:10.1177/0022034510385236
PMCID: PMC3144100  PMID: 21135192
adaptive immunity; bone matrix; cytokine; innate immunity; IL-1; osteoblast; osteoclast; RANK ligand; TNF
2.  Functional human T-cell immunity and osteoprotegerin ligand control alveolar bone destruction in periodontal infection  
Periodontitis, a prime cause of tooth loss in humans, is implicated in the increased risk of systemic diseases such as heart failure, stroke, and bacterial pneumonia. The mechanisms by which periodontitis and antibacterial immunity lead to alveolar bone and tooth loss are poorly understood. To study the human immune response to specific periodontal infections, we transplanted human peripheral blood lymphocytes (HuPBLs) from periodontitis patients into NOD/SCID mice. Oral challenge of HuPBL-NOD/SCID mice with Actinobacillus actinomycetemcomitans, a well-known Gram-negative anaerobic microorganism that causes human periodontitis, activates human CD4+ T cells in the periodontium and triggers local alveolar bone destruction. Human CD4+ T cells, but not CD8+ T cells or B cells, are identified as essential mediators of alveolar bone destruction. Stimulation of CD4+ T cells by A. actinomycetemcomitans induces production of osteoprotegerin ligand (OPG-L), a key modulator of osteoclastogenesis and osteoclast activation. In vivo inhibition of OPG-L function with the decoy receptor OPG diminishes alveolar bone destruction and reduces the number of periodontal osteoclasts after microbial challenge. These data imply that the molecular explanation for alveolar bone destruction observed in periodontal infections is mediated by microorganism-triggered induction of OPG-L expression on CD4+ T cells and the consequent activation of osteoclasts. Inhibition of OPG-L may thus have therapeutic value to prevent alveolar bone and/or tooth loss in human periodontitis.
This article may have been published online in advance of the print edition. The date of publication is available from the JCI website, http://www.jci.org. J. Clin. Invest. 106:R59–R67 (2000).
PMCID: PMC3102542  PMID: 10995794
3.  Expression levels of novel cytokine IL-32 in periodontitis and its role in the suppression of IL-8 production by human gingival fibroblasts stimulated with Porphyromonas gingivalis  
Journal of Oral Microbiology  2012;4:10.3402/jom.v4i0.14832.
Background
IL-32 was recently found to be elevated in the tissue of rheumatoid arthritis and inflammatory bowel disease. Periodontitis is a chronic inflammatory disease caused by polymicrobial infections that result in soft tissue destruction and alveolar bone loss. Although IL-32 is also thought to be associated with periodontal disease, its expression and possible role in periodontal tissue remain unclear. Therefore, this study investigated the expression patterns of IL-32 in healthy and periodontally diseased gingival tissue. The expression of IL-32 in cultured human gingival fibroblasts (HGF) as well as effects of autocrine IL-32 on IL-8 production from HGF were also examined.
Methods
Periodontal tissue was collected from both healthy volunteers and periodontitis patients, and immunofluorescent staining was performed in order to determine the production of IL-32. Using real-time PCR and ELISA, mRNA expression and protein production of IL-32 in HGF, stimulated by Porphyromonas gingivalis (Pg), were also investigated.
Results
Contrary to our expectation, the production of IL-32 in the periodontitis patients was significantly lower than in the healthy volunteers. According to immunofluorescent microscopy, positive staining for IL-32 was detected in prickle and basal cell layers in the epithelium as well as fibroblastic cells in connective tissue. Addition of fixed Pg in vitro was found to suppress the otherwise constitutive expression of IL-32 mRNA and protein in HGF. However, recombinant IL-32 in vitro inhibited the expression of IL-8 mRNA by HGF stimulated with Pg. Interestingly, anti-IL-32 neutralizing antibody upregulated the IL-8 mRNA expression in non-stimulated HGF, indicating that constitutive expression of IL-32 in HGF suppressed IL-8 mRNA expression in the absence of bacterial stimulation.
Conclusion
These results indicate that IL-32 is constitutively produced by HGF which can be suppressed by Pg and may play a role in the downregulation of inflammatory responses, such as IL-8 production, in periodontal tissue.
doi:10.3402/jom.v4i0.14832
PMCID: PMC3307671  PMID: 22435084
Interleukin-32; periodontal disease; Porphyromonas gingivalis; human gingival fibroblast; Interleukin-8
4.  Is there a relationship between periodontitis and rheumatoid arthritis? 
Background:
Growth of scientific evidence suggests an exquisite association between oral infection and systemic diseases. Though etiologies of periodontitis and rheumatoid arthritis (RA) are separate, their underlying pathological processes are sufficient to warrant consideration of hypothesis that individuals at risk of developing RA may also be at the risk of developing periodontitis and vice versa.
Materials and Methods:
To test their relationship, a study was carried out on 80 individuals. Part A: Forty subjects having rheumatoid arthritis (RA group) were compared to 40 controls without arthritis (NRA group). Their periodontal indices rheumatoid arthritis clinical laboratory parameters were also correlated with periodontitis in group. Part B: Omplete periodontal treatment was done for 10 patients of group suffering from periodontitis. All parameters of periodontal indices were measured pre-operatively and weeks after completion of periodontal treatment.
Results:
(1) There was high prevalence of mild (12.5%) to moderate (75%) periodontitis in group. (2) Extent severity of periodontal disease rheumatoid arthritis were positively correlated. (3) Statistically significant differences were present in periodontal parameters of RA group compared to NRA group. (4) There was statistically, significant reduction in parameters postoperatively with concomitant decrease in periodontal parameters in RA group.
Conclusion:
Thus, an association exists between periodontal disease with an underlying dysregulation of the molecular pathways in the inflammatory response. Also, there are significant management implications in the future as new host modifying medications are developed.
doi:10.4103/0972-124X.94599
PMCID: PMC3357028  PMID: 22628958
Inflammation; periodontitis; relationship; rheumatoid arthritis
5.  Diabetes and periodontal disease 
Journal of Pharmacy & Bioallied Sciences  2012;4(Suppl 2):S280-S282.
Diabetes mellitus is a systemic disease characterized by increased blood glucose levels and abnormalities of lipid metabolism due to absence or decreased level of insulin. It affects all the body organs and their functions either directly or indirectly. Every dentist should have a basic understanding of the etiopathogenesis, oral and systemic manifestations of this disease. The periodontal diseases are a consequence of extension of the gingival inflammation into the underlying supporting structures of the periodontium, initiated by the presence of plaque and its products on the surfaces of the teeth and the adjoining structures. The progression of periodontal disease is influenced by variety of factors like microorganisms, host response, systemic background, and genetic makeup of the host. Amongst them, diabetes mellitus tops the list. Diabetes and periodontitis influence the clinical outcome of each other and control of both influences the clinical improvement of each.
doi:10.4103/0975-7406.100251
PMCID: PMC3467897  PMID: 23066270
Diabetes mellitus; periodontitis; vascular changes
6.  Systemic Diseases Caused by Oral Infection 
Clinical Microbiology Reviews  2000;13(4):547-558.
Recently, it has been recognized that oral infection, especially periodontitis, may affect the course and pathogenesis of a number of systemic diseases, such as cardiovascular disease, bacterial pneumonia, diabetes mellitus, and low birth weight. The purpose of this review is to evaluate the current status of oral infections, especially periodontitis, as a causal factor for systemic diseases. Three mechanisms or pathways linking oral infections to secondary systemic effects have been proposed: (i) metastatic spread of infection from the oral cavity as a result of transient bacteremia, (ii) metastatic injury from the effects of circulating oral microbial toxins, and (iii) metastatic inflammation caused by immunological injury induced by oral microorganisms. Periodontitis as a major oral infection may affect the host's susceptibility to systemic disease in three ways: by shared risk factors; subgingival biofilms acting as reservoirs of gram-negative bacteria; and the periodontium acting as a reservoir of inflammatory mediators. Proposed evidence and mechanisms of the above odontogenic systemic diseases are given.
PMCID: PMC88948  PMID: 11023956
7.  The Relationship Between Periodontal Disease (Pd) and Cardiovascular Disease (Cvd). 
The recent focus on the potential link between periodontal and cardiovascular disease (PD and CVD) is part of the larger renewed interest on the role of infection and inflammation in the etiology of atherosclerosis and its clinical manifestations. Periodontal Disease is an inflammatory process affecting the periodontium, the tissue that surrounds and supports the teeth. The process usually starts with an inflammatory process of the gum (gingivitis) but it may progress with an extensive involvement of the gum, as well as the periodontal ligament and the bone surrounding the teeth resulting in substantial bone loss. Periodontal disease is a common oral pathological condition in the adult age and represents the leading cause of tooth loss. PD prevalence increases with age and there are estimates that up to 49,000,000 Americans may suffer from some form of gum disease. The gingival plaque associated with PD is colonized by a number of gram-positive and gram-negative bacteria that have been shown to affect the initiation and development of PD and have been associated with the potential etiological role of PD in CVD and other chronic conditions. A potential etiological link between PD and CVD may have important public health implications as both the exposure (PD) and the outcomes (CVD) are highly prevalent in industrialized societies. In situations in which both the exposure and the outcome are highly prevalent even modest associations, like those observed in the studies reporting on the link between PD and CVD outcomes, may have relevance. There are not definite data on the effect of periodontal treatment on CVD clinical outcomes (either in primary or secondary prevention) however it should be pointed out that the limited (both in terms of numbers and study design) experimental evidence in humans suggests a possible beneficial effect of periodontal treatment of indices of functional and structural vascular health.
doi:10.4084/MJHID.2010.030
PMCID: PMC3033151  PMID: 21415980
8.  MECHANISMS INVOLVED IN THE ASSOCIATION BETWEEN PERIDONTAL DISEASES AND CARDIOVASCULAR DISEASE 
Oral Diseases  2011;17(5):450-461.
It is now well accepted that besides the cholesterol associated mechanisms of atherogenesis, inflammation plays a crucial role in all stages of the development of the atherosclerotic lesion. This “inflammation hypothesis” raises the possibility that, through systemic elevations of pro-inflammatory cytokines, periodontal diseases might also contribute to systemic inflammation and, therefore, to atherogenesis. In fact, there is evidence that periodontal diseases are associated with higher systemic levels of high-sensitivity C-reactive protein and a low grade systemic inflammation. This phenomenon has been explained based on mechanisms associated with either the infectious or the inflammatory nature of periodontal diseases. The purposes of this article are to review (1) the evidence suggesting a role for oral bacterial species, particularly periodontal pathogens, in atherogenesis; (2) the potential mechanisms explaining an etiological role for oral bacteria in atherosclerosis; (3) the evidence suggesting that periodontal infections are accompanied by a heightened state of systemic inflammation; (4) the potential sources of systemic inflammatory biomarkers associated with periodontal diseases; and (5) the effects of periodontal therapy on systemic inflammatory biomarkers and cardiovascular risk.
doi:10.1111/j.1601-0825.2010.01784.x
PMCID: PMC3373016  PMID: 21223455
Cardiovascular disease; atherosclerosis; periodontal diseases; infection; periodontal pathogens; bacteremia; inflammatory response; systemic biomarkers; C-reactive protein
9.  Periodontal inflammation and bone loss in aged mice 
Journal of periodontal research  2010;45(4):574-578.
Background and objective
Young mice do not develop measurable periodontal bone loss, unless heavily infected with human periodontal pathogens. However, mice with genetically altered immune system are unable to control their own oral flora and develop periodontitis early in life. Based on the potential of the indigenous oral microbiota to cause periodontitis, we hypothesized that normal mice may ultimately develop inflammatory periodontal bone loss, i.e., as a function of age. If confirmed, this could serve as an aging model of chronic periodontitis.
Materials and methods
Periodontal bone levels were measured as the distance from the cementoenamel junction (CEJ) to the alveolar bone crest (ABC), in young (8-10 weeks of age), old (≥ 18 months of age), and mice of intermediate ages. Differential expression of inflammatory mediators in the gingivae of young and old mice was determined by quantitative real-time PCR.
Results
In comparison to young mice, old mice displayed significantly (p < 0.05) increased periodontal bone loss, accompanied by elevated expression of proinflammatory cytokines (interleukin-1β, tumor necrosis factor-α, and interleukin-17A) and innate immune receptors involved in the induction or amplification of inflammation (Toll-like receptor 2, CD14, CD11b, CD18, complement C5a receptor, and triggering receptor expressed on myeloid cells-3).
Conclusion
Mice develop naturally-induced periodontal bone loss as a function of age. This aging model of periodontitis represents a genuinely chronic model to study mechanisms of periodontal tissue destruction.
doi:10.1111/j.1600-0765.2009.01245.x
PMCID: PMC2894296  PMID: 20337897
Animal model; Alveolar bone; Chronic periodontitis; Inflammation; Innate immunology
10.  Complement and Periodontitis 
Biochemical pharmacology  2010;80(12):1992-2001.
Although the complement system is centrally involved in host defense, its overactivation or deregulation (e.g., due to inherent host genetic defects or due to pathogen subversion) may excessively amplify inflammation and contribute to immunopathology. Periodontitis is an oral infection-driven chronic inflammatory disease which exerts a systemic impact on health. This paper reviews evidence linking complement to periodontal inflammation and pathogenesis. Clinical and histological observations show a correlation between periodontal inflammatory activity and local complement activation. Certain genetic polymorphisms or deficiencies in specific complement components appear to predispose to increased susceptibility to periodontitis. Animal model studies and in vitro experiments indicate that periodontal bacteria can either inhibit or activate distinct components of the complement cascade. Porphyromonas gingivalis, a keystone species in periodontitis, subverts complement receptor 3 and C5a anaphylatoxin receptor signaling in ways that promote its adaptive fitness in the presence of non-productive inflammation. Overall, available evidence suggests that complement activation or subversion contributes to periodontal pathogenesis, although not all complement pathways or functions are necessarily destructive. Effective complement-targeted therapeutic intervention in periodontitis would require determining the precise roles of the various inductive or effector complement pathways. This information is essential as it may reveal which specific pathways need to be blocked to counteract microbial evasion and inflammatory pathology or, conversely, be enhanced to promote host immunity.
doi:10.1016/j.bcp.2010.06.017
PMCID: PMC2955993  PMID: 20599785
11.  The Management of Inflammation in Periodontal Disease 
Journal of periodontology  2008;79(8 Suppl):1601-1608.
It has become clear in recent years that periodontitis is an inflammatory disease initiated by oral microbial biofilm. This distinction implies that it is the host response to the biofilm that destroys the periodontium in the pathogenesis of the disease. As our understanding of pathways of inflammation has matured, a better understanding of the molecular basis of resolution of inflammation has emerged. Resolution of inflammation is an active, agonist-mediated, well-orchestrated return of tissue homeostasis. There is an important distinction between anti-inflammation and resolution; anti-inflammation is pharmacologic intervention in inflammatory pathways, whereas resolution is biologic pathways restoring homeostasis. A growing body of research suggests that chronic inflammatory periodontal disease involves a failure of resolution pathways to restore homeostasis. This article reviews the resolution of inflammation in the context of periodontal disease and the potential for the modification of resolution pathways for the prevention and treatment of periodontal diseases. Proof-of-concept studies in the 1980s demonstrated that pharmacologic anti-inflammation prevented and slowed the progression of periodontal diseases in animals and man. However, the side-effect profile of such therapies precluded the use of non-steroidal anti-inflammatory drugs or other enzyme inhibitors or receptor antagonists in periodontal therapy. The isolation and characterization of resolving agonist molecules has opened a new area of research using endogenous lipid mediators of resolution as potential therapeutic agents for the management of inflammatory periodontitis. Work in animal models of periodontitis has revealed the potential of this therapeutic approach for its prevention and treatment and forced the reconsideration of our understanding of the pathogenesis of human periodontal diseases.
doi:10.1902/jop.2008.080173
PMCID: PMC2563957  PMID: 18673016
Anti-inflammatory; lipoxins; Porphyromonas gingivalis; periodontal disease; resolvin E1
12.  Effect of anti-rheumatic agents on periodontal parameters and biomarkers of inflammation: a systematic review and meta-analysis 
Purpose
Anti-rheumatic agents target common molecular pathways of inflammation in rheumatoid arthritis (RA) and periodontitis. The purpose of this study was to determine the relative effect of anti-rheumatic agents on the levels of inflammatory biomarkers and periodontal inflammation in RA patients with periodontitis.
Methods
A systematic review and meta-analysis were conducted of studies comparing periodontal parameters of inflammation, such as bleeding on probing, and biomarkers of inflammation in RA patients with periodontitis and healthy adults with and without periodontitis. The search included the electronic databases MEDLINE, Cochrane Database of Systematic Reviews, and Google Scholar, inclusive through October 2011, with no language restrictions. Hand searches were conducted of the bibliographies of related journals and systematic reviews. Observational and interventional studies assessing the effects of antirheumatic therapy qualified for inclusion. Two reviewers performed independent data extraction and risk-of-bias assessment. Of the 187 identified publications, 13 studies fulfilled the inclusion criteria.
Results
When compared to healthy adults without periodontitis, RA subjects were found to have significantly higher levels of bleeding on probing and limited evidence of higher levels of interleukin-1β and tumor necrosis factor-α (TNF-α) in gingival crevicular fluid and saliva. No consistent differences were found in periodontal parameters and inflammatory biomarkers between RA subjects and adults with periodontitis. Studies evaluating the effect of anti-TNF-α therapy in RA subjects with periodontitis have yielded inconsistent results.
Conclusions
There are limited data, however, to suggest that anti-TNF-α agents can reduce local production of inflammatory cytokines and periodontal inflammation in RA patients with periodontitis.
doi:10.5051/jpis.2012.42.1.3
PMCID: PMC3296933  PMID: 22413068
Periodontitis; Rheumatoid arthritis; Tumor necrosis factor-alpha
13.  Direct Recognition of Fusobacterium nucleatum by the NK Cell Natural Cytotoxicity Receptor NKp46 Aggravates Periodontal Disease 
PLoS Pathogens  2012;8(3):e1002601.
Periodontitis is a common human chronic inflammatory disease that results in the destruction of the tooth attachment apparatus and tooth loss. Although infections with periopathogenic bacteria such as Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum) are essential for inducing periodontitis, the nature and magnitude of the disease is determined by the host's immune response. Here, we investigate the role played by the NK killer receptor NKp46 (NCR1 in mice), in the pathogenesis of periodontitis. Using an oral infection periodontitis model we demonstrate that following F. nucleatum infection no alveolar bone loss is observed in mice deficient for NCR1 expression, whereas around 20% bone loss is observed in wild type mice and in mice infected with P. gingivalis. By using subcutaneous chambers inoculated with F. nucleatum we demonstrate that immune cells, including NK cells, rapidly accumulate in the chambers and that this leads to a fast and transient, NCR1-dependant TNF-α secretion. We further show that both the mouse NCR1 and the human NKp46 bind directly to F. nucleatum and we demonstrate that this binding is sensitive to heat, to proteinase K and to pronase treatments. Finally, we show in vitro that the interaction of NK cells with F. nucleatum leads to an NCR1-dependent secretion of TNF-α. Thus, the present study provides the first evidence that NCR1 and NKp46 directly recognize a periodontal pathogen and that this interaction influences the outcome of F. nucleatum-mediated periodontitis.
Author Summary
Periodontal disease is a common bacterial-induced inflammatory process in which F. nucleatum and P. gingivalis infections lead to the destruction of the teeth supporting attachment apparatus. Previous reports demonstrated that immune cells aggravate the severity of the disease. However, whether NK cells in general and NKp46 (a major killer receptor expressed by NK cells) in particular, play a protective or destructive role in this disease is unknown. Using mice deficient in NCR1 (the mouse orthlogue of NKp46), we demonstrate that oral infection of mice with F. nucleatum, but not with P. gingivalis results in an NCR1-dependent alveolar bone loss. In addition, we show that F. nucleatum is recognized by NCR1 and NKp46 directly and that this recognition leads to the secretion of TNF-α, a central cytokine critically involved in the pathogenesis of periodontal destruction. Collectively, we show that NCR1 and NKp46 play a critical role in the pathogenesis of F. nucleatum-mediated periodontitis.
doi:10.1371/journal.ppat.1002601
PMCID: PMC3310798  PMID: 22457623
14.  MAPK Usage in Periodontal Disease Progression 
Journal of Signal Transduction  2012;2012:308943.
In periodontal disease, host recognition of bacterial constituents, including lipopolysaccharide (LPS), induces p38 MAPK activation and subsequent inflammatory cytokine expression, favoring osteoclastogenesis and increased net bone resorption in the local periodontal environment. In this paper, we discuss evidence that the p38/MAPK-activated protein kinase-2 (MK2) signaling axis is needed for periodontal disease progression: an orally administered p38α inhibitor reduced the progression of experimental periodontal bone loss by reducing inflammation and cytokine expression. Subsequently, the significance of p38 signaling was confirmed with RNA interference to attenuate MK2-reduced cytokine expression and LPS-induced alveolar bone loss. MAPK phosphatase-1 (MKP-1), a negative regulator of MAPK activation, was also critical for periodontal disease progression. In MPK-1-deficient mice, p38-sustained activation increased osteoclast formation and bone loss, whereas MKP-1 overexpression dampened p38 signaling and subsequent cytokine expression. Finally, overexpression of the p38/MK2 target RNA-binding tristetraprolin (TTP) decreased mRNA stability of key inflammatory cytokines at the posttranscriptional level, thereby protecting against periodontal inflammation. Collectively, these studies highlight the importance of p38 MAPK signaling in immune cytokine production and periodontal disease progression.
doi:10.1155/2012/308943
PMCID: PMC3270463  PMID: 22315682
15.  Critical analysis of biomarkers in the current periodontal practice 
Periodontal disease is a chronic microbial infection that triggers inflammation-mediated loss of the periodontal ligament and alveolar bone that supports the teeth. Because of the increasing prevalence and associated comorbidities, there is a need for the development of new diagnostic tests that can detect the presence of active disease, predict future disease progression, and evaluate the response to periodontal therapy, thereby improving the clinical management of periodontal patients. The diagnosis of active phases of periodontal disease and the identification of patients at risk for active disease represent challenges for clinical investigators and practitioners. Advances in diagnostic research are moving toward methods whereby the periodontal risk can be identified and quantified by objective measures using biomarkers. Patients with periodontitis may have elevated circulating levels of specific inflammatory markers that can be correlated to the severity of the disease. Advances in the use of oral fluids as possible biological samples for objective measures of the current disease state, treatment monitoring, and prognostic indicators have boosted saliva- and other oral-based fluids to the forefront of technology. Gingival crevicular fluid (GCF) is an inflammatory exudate that can be collected at the gingival margin or within the gingival crevice. This article highlights recent advances in the use of biomarker-based disease diagnostics that focus on the identification of active periodontal disease from plaque biofilms, GCF, and saliva.
doi:10.4103/0972-124X.84376
PMCID: PMC3183658  PMID: 21976831
Biomarkers; C-telopeptide pyridinoline; gingival crevicular fluid; periodontal disease
16.  Treatment modalities and evaluation models for periodontitis 
Periodontitis is the most common localized dental inflammatory disease related with several pathological conditions like inflammation of gums (gingivitis), degeneration of periodontal ligament, dental cementum and alveolar bone loss. In this perspective, the various preventive and treatment modalities, including oral hygiene, gingival irrigations, mechanical instrumentation, full mouth disinfection, host modulation and antimicrobial therapy, which are used either as adjunctive treatments or as stand-alone therapies in the non-surgical management of periodontal infections, have been discussed. Intra-pocket, sustained release systems have emerged as a novel paradigm for the future research. In this article, special consideration is given to different locally delivered anti-microbial and anti inflammatory medications which are either commercially available or are currently under consideration for Food and Drug Administration (FDA) approval. The various in vitro dissolution models and microbiological strain investigated to impersonate the infected and inflamed periodontal cavity and to predict the in vivo performance of treatment modalities have also been thrashed out. Animal models that have been employed to explore the pathology at the different stages of periodontitis and to evaluate its treatment modalities are enlightened in this proposed review.
doi:10.4103/2230-973X.104394
PMCID: PMC3555006  PMID: 23373002
Chemotherapeutic agents; intra-pocket devices; mechanical therapies; oral hygiene
17.  Destructive effects of smoking on molecular and genetic factors of periodontal disease 
Many epidemiological evidences have proven the association between smoking and periodontal disease. The causality can be further established by linking findings of traditional epidemiological studies with the developments in molecular techniques that occurred in the last decade. The present article reviews recent studies that address the effect of smoking on molecular and genetic factors in periodontal disease. Most findings support the fact that tobacco smoking modulates destruction of the periodontium through different pathways: microcirculatory and host immune systems, connective tissue, and bone metabolism. Although smokers experience an increased burden of inflammatory responses to microbial challenges compared to non-smokers, understanding the association between smoking and periodontal diseases involves substantial problems with respect to accuracy of measurements, and particularly, sampling of many subjects. It remains unclear whether genetic susceptibility to periodontal disease is influenced by exposure to smoking or the effect of smoking on periodontal disease is influenced by genetic susceptibility. Employment of molecular techniques may play a key role in further elucidation of mechanisms linking smoking and periodontal destruction, the direct relationship as environmental factors and indirect relationship through genetic factors.
doi:10.1186/1617-9625-8-4
PMCID: PMC2836317  PMID: 20170537
18.  Pathogen-induced inflammation at sites distant from oral infection: bacterial persistence and induction of cell-specific innate immune inflammatory pathways 
Molecular oral microbiology  2010;25(5):305-316.
SUMMARY
A hallmark of infection with the gram-negative pathogen Porphyromonas gingivalis is the induction of a chronic inflammatory response. P. gingivalis induces a local chronic inflammatory response that results in oral inflammatory bone destruction, which manifests as periodontal disease. In addition to chronic inflammation at the initial site of infection, mounting evidence has accumulated supporting a role for P. gingivalis-mediated periodontal disease as a risk factor for several systemic diseases including, diabetes, preterm birth, stroke, and atherosclerotic cardiovascular disease. A growing number of in vitro studies have demonstrated that P. gingivalis infection stimulates cell activation commensurate with expected responses paralleling inflammatory atherosclerotic-type responses. Furthermore, various mouse models have been used to examine the ability of P. gingivalis to stimulate chronic inflammatory plaque accumulation and recent studies have pointed to a pivotal role for innate immune signaling via the Toll-like receptors in the chronic inflammation associated with P. gingivalis infection. In this review we discuss the pathogen and host cell specificity of these responses and discuss possible mechanisms by which this oral pathogen can induce and maintain a chronic state of inflammation at sites distant from oral infection.
doi:10.1111/j.2041-1014.2010.00582.x
PMCID: PMC2951292  PMID: 20883220
atherosclerosis; bacterial persistence; immune evasion; innate immunity; Porphyromonas gingivalis; Toll-like receptor
19.  Periodontal treatment effects on endothelial function and cardiovascular disease biomarkers in subjects with chronic periodontitis: protocol for a randomized clinical trial 
Trials  2011;12:46.
Background
Periodontal disease (PD) is an infectious clinical entity characterized by the destruction of supporting tissues of the teeth as the result of a chronic inflammatory response in a susceptible host. It has been proposed that PD as subclinical infection may contribute to the etiology and to the pathogenesis of several systemic diseases including Atherosclerosis. A number of epidemiological studies link periodontal disease/edentulism as independent risk factor for acute myocardial infarction, peripheral vascular disease, and cerebrovascular disease. Moreover, new randomized controlled clinical trials have shown an improvement on cardiovascular surrogate markers (endothelial function, sICAM, hsPCR level, fibrinogen) after periodontal treatment. Nonetheless, such trials are still limited in terms of external validity, periodontal treatment strategies, CONSORT-based design and results consistency/extrapolation. The current study is designed to evaluate if periodontal treatment with scaling and root planning plus local delivered chlorhexidine improves endothelial function and other biomarkers of cardiovascular disease in subjects with moderate to severe periodontitis.
Methods/Design
This randomized, single-blind clinical trial will be performed at two health centers and will include two periodontal treatment strategies. After medical/periodontal screening, a baseline endothelium-dependent brachial artery flow-mediated dilatation (FMD) and other systemic surrogate markers will be obtained from all recruited subjects. Patients then will be randomized to receive either supragingival/subgingival plaque cleaning and calculus removal plus chlorhexidine (treatment group) or supragingival plaque removal only (control group). A second and third FMD will be obtained after 24 hours and 12 weeks in both treatment arms. Each group will consist of 49 patients (n = 98) and all patients will be followed-up for secondary outcomes and will be monitored through a coordinating center. The primary outcomes are FMD differences baseline, 24 hours and 3 months after treatment. The secondary outcomes are differences in C-reactive protein (hs-CRP), glucose serum levels, blood lipid profile, and HOMA index.
Discussion
This RCT is expected to provide more evidence on the effects of different periodontal treatment modalities on FMD values, as well as to correlate such findings with different surrogate markers of systemic inflammation with cardiovascular effects.
Trial registration number
ClinicalTrials.gov Identifier: NCT00681564.
doi:10.1186/1745-6215-12-46
PMCID: PMC3049125  PMID: 21324167
20.  Molecular Epidemiology of Oral Treponemes Associated with Periodontal Disease 
Journal of Clinical Microbiology  1998;36(5):1399-1403.
Periodontitis, a disease responsible for tooth loss worldwide, is characterized by chronic inflammation of the periodontium, eventually leading to destruction of periodontal ligaments and supporting alveolar bone. Spirochetes, identified by dark-field microscopy as being the most predominant bacteria in advanced lesions, are thought to play a causative role. Various spirochetal morphotypes were observed, but most of these morphotypes are as yet uncultivable. To assess the role of these organisms we designed oligonucleotide probes for the identification of both cultivable and so far uncultivable spirochetes in periodontitis patients. Subgingival plaque specimens taken from diseased sites (n = 200) and healthy control sites (n = 44) from 53 patients with rapidly progressive periodontitis (RPP) were submitted to direct in situ hybridization or dot blot hybridization after prior amplification with eubacterial primers. Spirochetes were found in all patients, but their distributions varied considerably. Parallel use of oligonucleotide probes specific for cultivable or so far uncultivable treponemes suggested the presence of novel yet unknown organisms at a high frequency. These uncultivable treponemes were visualized by fluorescence in situ hybridization, and their morphologies, sizes, and numbers could be estimated. All RPP patients included in this study harbored oral treponemes that represent either novel species, e.g., Treponema maltophilum, or uncultivable phylotypes. Therefore, it is necessary to include these organisms in etiologic considerations and to strengthen efforts to cultivate these as yet uncultivable treponemes.
PMCID: PMC104836  PMID: 9574713
21.  Relationship Between Osteoporosis and Periodontal Disease: Review of the Literature 
Objective
Osteoporosis is a skeletal disease characterized by reduction in bone mass and micro architectural changes in the bone, which leads to increased bone fragility. The gold standard for the diagnosis of osteoporosis is the measurement of bone mineral density (BMD) by dual energy x-ray absorptiometry (DXA). Periodontal disease is a chronic destructive disease which can occur in adults, young people and children. Periodontal pathogens cause inflammation of the gingiva which is called gingivitis. When periodontal tissue destruction and alveolar bone loss happen, it is called periodontitis. Since both osteoporosis and periodontal diseases are bone destructive diseases, it has been hypothesized that osteoporosis could be a risk factor for the progression of periodontal disease. The aim of this study is to review the articles assessing the relationship between osteoporosis and periodontitis
Materials and Methods:
In this review, articles were selected from PubMed between January of 1998 and June 2010. Amongst 508 articles identified from the electronic search, 17 articles were selected for a full-text reading based on the inclusion and exclusion criteria.
Results:
Among the 17 studies focused on, 11 studies showed a positive relation between osteoporosis and periodontal disease and the six remaining studies found no significant relation between osteoporosis and periodontal disease.
Conclusion:
These data indicate a greater propensity to lose alveolar bone in subjects with osteoporosis, especially in subjects with preexisting periodontitis. This would indicate that osteoporosis or low systemic BMD should be considered a risk factor for periodontal disease progression.
PMCID: PMC3536461  PMID: 23323188
Periodontitis; Tooth Loss; Bone Density; Osteoporosis
22.  Effect of smoking on gingival microvasculature: A histological study 
Background:
Smoking has been reported as a major risk factor for periodontal disease. Studies have demonstrated decreased bleeding on probing and reduced inflammatory response among smokers, which has been attributed to the alterations in gingival microvasculature, gingival epithelium. In previous investigations, vascular and epithelial changes have been studied in the gingival tissues of smokers suffering from periodontitis and compared with healthy periodontium of non smokers. Inflammation is known to cause vascular and epithelial changes in the gingiva on its own in the absence of smoking. Hence, in the present investigation, an attempt is made to study and to compare the vascular and epithelial changes in the gingiva of smokers and non smokers suffering from chronic periodontitis.
Aim of Study:
The purpose of this study was to evaluate the vascular and epithelial changes in gingiva of smokers and non smokers with chronic periodontitis.
Study Design:
Cross sectional study
Materials and Methods:
Gingival biopsies were obtained from 33 male patients (18 smokers and 15 non smokers) who were undergoing periodontal therapy or extraction. The sections were stained with eosin and hematoxylin. Vascular density, area of the lumen, and epithelial thickness were assessed using histomorphometric image analysis.
Statistical Method:
Data was analyzed using student unpaired ‘t’ test, Karl Pearsons correlation, and Chi-square test.
Results:
The mean blood vessel density for smokers was 12.388±6.472 and for non smokers was 14.800±4.91. The mean lumen area of the vessels among smokers and non smokers was 19.290±8.775 μm2 and 20.044±7.896 μm2, respectively. The mean epithelial thickness among smokers was 150.551±32.994 μ and 134.941±30.63 μ for non smokers.
Conclusion:
Based on the present histomorphometric study, it could be concluded that smokers have less vascular density and reduced lumen area and increased epithelial thickness than non smokers. However, these changes were not statistically significant.
doi:10.4103/0972-124X.92566
PMCID: PMC3283930  PMID: 22368357
Chronic periodontitis; gingival epithelium; gingival microvasculature; smoking; vascular density
23.  Salivary enzymes as diagnostic markers for detection of gingival/periodontal disease and their correlation with the severity of the disease 
Context:
Host responses to periodontal disease include the production of different enzymes released by stromal, epithelial or inflammatory cells. Important enzymes associated with cell injury and cell death are aspartate aminotransferase, alanine aminotransferase (AST, ALT), alkaline phosphatase, acidic phosphatase (ALP, ACP), and gama glutamyl transferase (GGT). Changes in enzymatic activity reflect metabolic changes in the gingiva and periodontium, in the inflammation.
Aims:
In this article we examined the activity of AST, ALT, GGT, ALP, and ACP in the saliva from patients with periodontal disease, before and after periodontal treatment (experimental group — 20 gingivitis patients and 20 periodontitis patients), and in the saliva from healthy subjects (control group — 20 samples).
Settings and Design:
Periodontal disease was determined based on the clinical parameters (gingival index (GI), probing depth (PD), and clinical attachment loss (CAL)). Patients with periodontal disease were under conventional periodontal treatment.
Materials and Methods:
The stimulated saliva of the patient was collected in a sterile test tube and analyzed using the Automatic Analyzer.
Results:
The obtained results showed statistically significant increased activity of AST, ALT, GGT, ALP, and ACP in the saliva from patients with periodontal disease, in relation to the control group. A significant reduction in the enzyme levels was seen after conventional periodontal therapy.
Conclusions:
Based on these results, it can be assumed that the salivary enzymes (AST, ALT, GGT, ALP, and ACP) can be considered as biochemical markers for evaluating the diagnosis and prognosis of the functional condition of periodontal tissues in disease and health, and in the evaluation of the therapy effects in periodontal disease.
doi:10.4103/0972-124X.100911
PMCID: PMC3498704  PMID: 23162329
Enzymes; periodontal disease; saliva
24.  Comparative analysis of GCF β-glucuronidase level in diabetic and nondiabetic patients with chronic periodontitis: A clinicobiochemical study 
Recent evidences prove that, release of potent lysosomal enzymes e.g. β-Glucuronidase by degranulation of polymorponuclear leukocytes in host gingiva may contribute significantly to tissue destruction and the pathogenesis of periodontal disease. The purpose of the present study was to compare and correlate GCF β-Glucuronidase with periodontal status among diabetic and non-diabetic patients with chronic periodontitis. A total number of 75 patients were equally divided into Group I (control group), Group II (non diabetic with chronic periodontitis) and Group III (diabetic with chronic periodontitis). Clinical parameters like Plaque index, Gingival index, Probing Pocket Depth and RBS were recorded. The β-Glucuronidase level in GCF of all three groups was determined by spectrophotometric analysis. It was observed that the periodontitis patients irrespective of their diabetic status, showed increased periodontal destruction with elevated level of β-Glucuronidase than the controls. Also, the diabetic patients showed increased severity of periodontal destruction and the elevated level of β-Glucuronidase, thus indicating diabetics at a higher risk for progressive periodontal destruction.
doi:10.4103/0972-124X.44092
PMCID: PMC2813552  PMID: 20142938
β - Glucuronidase; chronic periodontitis; diabetes; GCF
25.  Periodontitis and diabetes: a two-way relationship 
Diabetologia  2011;55(1):21-31.
Periodontitis is a common chronic inflammatory disease characterised by destruction of the supporting structures of the teeth (the periodontal ligament and alveolar bone). It is highly prevalent (severe periodontitis affects 10–15% of adults) and has multiple negative impacts on quality of life. Epidemiological data confirm that diabetes is a major risk factor for periodontitis; susceptibility to periodontitis is increased by approximately threefold in people with diabetes. There is a clear relationship between degree of hyperglycaemia and severity of periodontitis. The mechanisms that underpin the links between these two conditions are not completely understood, but involve aspects of immune functioning, neutrophil activity, and cytokine biology. There is emerging evidence to support the existence of a two-way relationship between diabetes and periodontitis, with diabetes increasing the risk for periodontitis, and periodontal inflammation negatively affecting glycaemic control. Incidences of macroalbuminuria and end-stage renal disease are increased twofold and threefold, respectively, in diabetic individuals who also have severe periodontitis compared to diabetic individuals without severe periodontitis. Furthermore, the risk of cardiorenal mortality (ischaemic heart disease and diabetic nephropathy combined) is three times higher in diabetic people with severe periodontitis than in diabetic people without severe periodontitis. Treatment of periodontitis is associated with HbA1c reductions of approximately 0.4%. Oral and periodontal health should be promoted as integral components of diabetes management.
doi:10.1007/s00125-011-2342-y
PMCID: PMC3228943  PMID: 22057194
Diabetes; Diabetes complications; Periodontal diseases; Periodontitis; Type 1 diabetes mellitus; Type 2 diabetes mellitus

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