Type 1 diabetes predisposes to enhanced gingival leukocyte margination and macromolecule extravasation in vivo

Better Gingival Status in Patients with Comorbidity of Type 1 Diabetes and Thyroiditis in Comparison with Patients with Type 1 Diabetes and No Thyroid Disease-A Preliminary Study

Periodontal disease has been postulated as one of the chronic complications of diabetes. The prevalence of autoimmune thyroiditis in type 1 diabetes (T1D) is higher. The aim of the study was to determine the association between the presence of thyroiditis and gingival status in adults with T1D. A total of 264 patients, 119 men aged 18-45, diagnosed with T1D were included. For further analysis, the study group was divided into two subgroups, with or without autoimmune thyroiditis. Gingival status was assessed with the use of gingival indices. Patients diagnosed with T1D and thyroiditis presented lower plaque accumulation (p = 0.01) and lower-grade gingivitis (p = 0.02). Approximal Plaque Index (API) in all study groups correlated positively with age (Rs = 0.24; p = 0.0001), body mass index (BMI) (Rs = 0.22; p = 0.0008), hemoglobin A1c (HbA1c) (Rs = 0.18; p = 0.006), high-sensitivity C-Reactive Protein (hsCRP) (Rs = 0.17; p = 0.009), total cholesterol (T-Chol) (Rs = 0.17; p = 0.01) and negatively with thyroid-stimulating hormone (TSH) (Rs = -0.2; p = 0.02). Stepwise multivariate linear regression analysis indicated TSH, BMI and gender as independent predictors of dental plaque accumulation in patients with T1D. Autoimmune thyroiditis was associated with a lower accumulation of dental plaque and better gingival status in patients with T1D.

Salivary macrophage activation-related chemokines and mitogen-activated kinase kinase (MAPKK)-degrading proteolytic activity in type 1 diabetes mellitus

BACKGROUND

This cross-sectional study aimed to evaluate salivary concentrations of macrophage activation-related chemokines and mitogen-activated kinase kinase (MAPKK)-degrading proteolytic activity in children and adolescents with and without type 1 diabetes mellitus (T1DM).

METHODS

A total of 122 children and adolescents (65 T1DM patients, 50.8% female, mean age:10.9 years; 57 systemically healthy controls, 36.8% female, mean age: 9.5 years) were included in the study. Salivary concentrations of interferon gamma inducible protein-10 (IP-10), monocyte chemoattractant protein (MCP)-1, MCP-2, MCP-3, MCP-4, macrophage-derived chemokine (MDC), macrophage migration inhibitory factor (MIF), monokine induced by interferon gamma (MIG), and macrophage inflammatory protein-1 alpha (MIP-1α) were quantified using a bead-based technique. MAPKK-degrading proteolytic activity was detected using fluorescent peptide substrates.

RESULTS

The T1DM group had higher plaque index (PI%, p = 0.032) and bleeding on probing (BOP%, p = 0.045) scores, and lower decayed, missing, filled teeth (dmft/DMFT, p = 0.002) index scores compared to the healthy controls. Compared to the controls, salivary MCP-1 (p = 0.007), MCP-3 (p < 0.001), MIG (p = 0.007), and MIP-1α (p = 0.033) concentrations were elevated whereas MCP-4 concentrations decreased (p < 0.001) in the T1DM group. After adjusting for age, PI%, BOP%, and dmft/DMFT scores, significant differences in salivary concentrations of MIG (p = 0.033) and MIP-1α (p = 0.017) were observed between the groups. Moreover, protease activities directed to the cleavage sites of MEK23-18 (p = 0.001), MKK6b7-22 (p = 0.007), MKK451-66 (p = 0.005), MKK7b37-52 (p = 0.034), and MKK7b69-84 (p = 0.009) were elevated in the T1DM group.

CONCLUSION

T1DM disrupts the salivary macrophage activation-related chemokine profile and dysregulates proteolytic MAPKK cleavage. These findings can be an outcome of the impaired systemic immune response in T1DM.

Potential Roles of Selectins in Periodontal Diseases and Associated Systemic Diseases: Could They Be Targets for Immunotherapy?

Periodontal diseases are predisposing factors to the development of many systemic disorders, which is often initiated via leukocyte infiltration and vascular inflammation. These diseases could significantly affect human health and quality of life. Hence, it is vital to explore effective therapies to prevent disease progression. Periodontitis, which is characterized by gingival bleeding, disruption of the gingival capillary's integrity, and irreversible destruction of the periodontal supporting bone, appears to be caused by overexpression of selectins in periodontal tissues. Selectins (P-, L-, and E-selectins) are vital members of adhesion molecules regulating inflammatory and immune responses. They are mainly located in platelets, leukocytes, and endothelial cells. Furthermore, selectins are involved in the immunopathogenesis of vascular inflammatory diseases, such as cardiovascular disease, diabetes, cancers, and so on, by mediating leukocyte recruitment, platelet activation, and alteration of endothelial barrier permeability. Therefore, selectins could be new immunotherapeutic targets for periodontal disorders and their associated systemic diseases since they play a crucial role in immune regulation and endothelium dysfunction. However, the research on selectins and their association with periodontal and systemic diseases remains limited. This review aims to discuss the critical roles of selectins in periodontitis and associated systemic disorders and highlights the potential of selectins as therapeutic targets.

The role of oral microbiome in periodontitis under diabetes mellitus

Periodontitis is among most common human inflammatory diseases and characterized by destruction of tooth-supporting tissues that will eventually lead to tooth loss. Diabetes mellitus (DM) is a group of metabolic disorders characterized by chronic hyperglycemia which results from defects in insulin secretion and/or insulin resistance. Numerous studies have provided evidence for the inter-relationship between DM and periodontitis that has been considered as the sixth most frequent complication of DM. However, the mechanisms are not fully understood yet. The impact of DM on periodontitis through hyperglycemia and inflammatory pathways is well described, but the effects of DM on oral microbiota remain controversial according to previous studies. Recent studies using next-generation sequencing technology indicate that DM can alter the biodiversity and composition of oral microbiome especially subgingival microbiome. This may be another mechanism by which DM risks or aggravates periodontitis. Thus, to understand the role of oral microbiome in periodontitis of diabetics and the mechanism of shifts of oral microbiome under DM would be valuable for making specific therapeutic regimens for treating periodontitis patients with DM or preventing diabetic patients from periodontitis. This article reviews the role of oral microbiome in periodontal health (symbiosis) and disease (dysbiosis), highlights the oral microbial shifts under DM and summarizes the mechanism of the shifts.

Novel Insight into the Mechanisms of the Bidirectional Relationship between Diabetes and Periodontitis

Periodontitis and diabetes are two major global health problems despite their prevalence being significantly underreported and underestimated. Both epidemiological and intervention studies show a bidirectional relationship between periodontitis and diabetes. The hypothesis of a potential causal link between the two diseases is corroborated by recent studies in experimental animals that identified mechanisms whereby periodontitis and diabetes can adversely affect each other. Herein, we will review clinical data on the existence of a two-way relationship between periodontitis and diabetes and discuss possible mechanistic interactions in both directions, focusing in particular on new data highlighting the importance of the host response. Moreover, we will address the hypothesis that trained immunity may represent the unifying mechanism explaining the intertwined association between diabetes and periodontitis. Achieving a better mechanistic insight on clustering of infectious, inflammatory, and metabolic diseases may provide new therapeutic options to reduce the risk of diabetes and diabetes-associated comorbidities.

The impact of diabetes on periodontal diseases

The susceptibility and severity of periodontal diseases is made more severe by diabetes, with the impact on the disease process inversely proportional to the level of glycemic control. Although type 1 diabetes mellitus and type 2 diabetes mellitus have different etiologies, and their impact on bone is not identical, they share many of the same complications. Studies in animals and humans agree that both forms of diabetes increase inflammatory events in periodontal tissue, impair new bone formation, and increase expression of RANKL in response to bacterial challenge. High levels of glucose, reactive oxygen species, and advanced glycation end-products are found in the periodontium of diabetic individuals and lead to increased activation of nuclear factor-kappa B and expression of inflammatory cytokines such as tumor necrosis factor and interleukin-1. Studies in animals, moreover, suggest that there are multiple cell types in periodontal tissues that are affected by diabetes, including leukocytes, vascular cells, mesenchymal stem cells, periodontal ligament fibroblasts, osteoblasts, and osteocytes. The etiology of periodontal disease involves the host response to bacterial challenge that is affected by diabetes, which increases the expression of RANKL and reduces coupled bone formation. In addition, the inflammatory response also modifies the oral microbiota to render it more pathogenic, as demonstrated by increased inflammation and bone loss in animals where bacteria are transferred from diabetic donors to germ-free hosts compared with transfer from normoglycemic donors. This approach has the advantage of not relying upon limited knowledge of the specific bacterial taxa to determine pathogenicity, and examines the overall impact of the microbiota rather than the presumed pathogenicity of a few bacterial groups. Thus, animal studies have provided new insights into pathogenic mechanisms that identify cause-and-effect relationships that are difficult to perform in human studies.

Development and validation of a predictive model for periodontitis using NHANES 2011-2012 data

AIM

To develop and validate a predictive model for moderate-to-severe periodontitis in the adult USA population, with data from the 2011-2012 National Health and Nutrition Examination Survey (NHANES) cycle.

MATERIAL AND METHODS

A subset of 3017 subjects aged >30 years, with >14 teeth present and having received a periodontal examination in addition to data collected on cardio-metabolic risk measures (smoking habit, body mass index [BMI], blood pressure, total cholesterol and glycated haemoglobin [HbA1c]) were used for model development by multivariable logistic regression.

RESULTS

The prevalence of moderate and severe periodontitis using CDC/AAP classification was 37.1% and 13.2%, respectively. A multivariable logistic regression model revealed that HbA1c ≥5.7% was significantly associated with moderate-to-severe periodontitis (odds ratio, OR = 1.29; p < 0.01). A predictive model including age, gender, ethnicity, HbA1c and smoking habit as variables had 70.0% sensitivity and 67.6% specificity in detecting moderate-to-severe periodontitis in US adults.

CONCLUSIONS

Periodontitis is a common disease in North American adults, and its prevalence is significantly higher in individuals with pre-diabetes or diabetes. The present study demonstrates that a model including age, gender, ethnicity, HbA1c and smoking habit could be used as a reliable screening tool for periodontitis in primary medical care settings to facilitate referral of patients at risk for periodontal examination and diagnosis.

Evaluating All Potential Oral Complications of Diabetes Mellitus

Diabetes mellitus (DM) is associated with several microvascular and macrovascular complications, such as retinopathy, nephropathy, neuropathy, and cardiovascular diseases. The pathogenesis of these complications is complex, and involves metabolic and hemodynamic disturbances, including hyperglycemia, insulin resistance, dyslipidemia, hypertension, and immune dysfunction. These disturbances initiate several damaging processes, such as increased reactive oxygen species (ROS) production, inflammation, and ischemia. These processes mainly exert their damaging effect on endothelial and nerve cells, hence the susceptibility of densely vascularized and innervated sites, such as the eyes, kidneys, and nerves. Since the oral cavity is also highly vascularized and innervated, oral complications can be expected as well. The relationship between DM and oral diseases has received considerable attention in the past few decades. However, most studies only focus on periodontitis, and still approach DM from the limited perspective of elevated blood glucose levels only. In this review, we will assess other potential oral complications as well, including: dental caries, dry mouth, oral mucosal lesions, oral cancer, taste disturbances, temporomandibular disorders, burning mouth syndrome, apical periodontitis, and peri-implant diseases. Each oral complication will be briefly introduced, followed by an assessment of the literature studying epidemiological associations with DM. We will also elaborate on pathogenic mechanisms that might explain associations between DM and oral complications. To do so, we aim to expand our perspective of DM by not only considering elevated blood glucose levels, but also including literature about the other important pathogenic mechanisms, such as insulin resistance, dyslipidemia, hypertension, and immune dysfunction.

Impact of Glycemic Levels in Type 2 Diabetes on Periodontitis

AIM

The aim is to study the effect of glycemic level in Type 2 diabetes and cardiovascular risk factors on periodontal health.

MATERIALS AND METHOD

Type 2 diabetic and nondiabetic patients in the age group of 35-80 years (n = 1700) were recruited for the study. Periodontal examination included as follows: Probing depth, clinical attachment level (CAL), gingival recession, and bleeding on probing. Periodontitis was diagnosed based on the CAL levels and diabetes was diagnosed based on glycated hemoglobin (HbA1c) levels. Body mass index, total cholesterol, triglyceride, and low-density lipoprotein (LDL) were assessed for cardiovascular risk. Patients were characterized into two groups as follows: diabetic (n = 1235) and nondiabetic (n = 465). Sociodemographic variables included were: age, sex, obesity, smoking, duration of diabetes, and periodontitis were assessed. SPSS version 20.0.1.0 was used for all the statistical assessments.

CONCLUSION

HbA1c and lipid levels were statistically significant with the severity of periodontitis (odds ratio [OR] [95% confidence interval [CI]: HbA1c 1.34 [1.019-1.21]; Total cholesterol 1.01 [1.03-1.42]; triglycerides 1.01 [1.01-1.14]; LDL 1.028 [1.08-1.71]). Smoking and obesity were also found to be significantly associated with the presence of periodontitis [OR (95% CI): smoking 1.35 (1.10-1.67); obesity 1.23 (1.73-2.05)]. The study concluded that uncontrolled HbA1c levels and elevated cardiovascular risk factors significantly increase the severity of periodontitis in Type 2 diabetes mellitus.

Type 1 Diabetes and Periodontal Health

It is well established that hyperglycemia affects periodontal outcomes. A body of evidence, predominantly over the past 20 years supports significant independent associations between periodontal disease and glycemic control or complications of diabetes. Association between periodontal tissue and hyperglycemia is possible through altered cellular immunity, increased proliferation of bacteria, microangiopathy, and formation of the advanced glycation end products. However, most studies focus solely on patients with type 2 diabetes or diabetes in general. There is still the paucity of data concerning patients with type 1 diabetes (T1D). Here, the authors consider the possible mechanisms linking periodontal disease with diabetes, focusing mainly on T1D and discuss possible diagnostic and therapeutic approaches.

Function of Pro-Resolving Lipid Mediator Resolvin E1 in Type 2 Diabetes

Programming of inflammation resolution is governed by a class of specialized pro-resolving lipid mediators (SPMs) that act in concert to modulate epithelial, endothelial, and immune cell function for restoration of homeostasis. The resolution circuits are altered in obesity and associated morbidities, including type 2 diabetes mellitus (T2D), through reduced production and/or action of SPMs, which can be rescued by therapeutic SPM delivery or up-regulation of SPM receptors. Resolvin E1 (RvE1), an eicosapentaenoic acid derivative, has potent pro-resolving and insulin-sensitizing actions mediated by BLT1 and ERV1 receptors in the vasculature and metabolic organs. Nonetheless, the RvE1-mediated increase in protective adipokines such as adiponectin in white adipose tissues, the enhancement of monocyte patrolling function in the vasculature, as well as the macrophage-clearing functions improve metabolic control in obese-prone conditions. RvE1-enhanced resolving function in obesity prevents dysbiosis of the gut microflora and increased gut permeability. These functions suggest that RE1 has therapeutic potential for immunometabolic alterations associated with T2D in patients with reduced inflammation resolving capacity. SPM profiling in individuals at risk for T2D and associated complications will help to advance personalized disease management and precision medicine.

Comorbidity of periodontal disease: two sides of the same coin? An introduction for the clinician

Increasing evidence has suggested an independent association between periodontitis and a range of comorbidities, for example cardiovascular disease, type 2 diabetes, rheumatoid arthritis, osteoporosis, Parkinson’s disease, Alzheimer’s disease, psoriasis, and respiratory infections. Shared inflammatory pathways are likely to contribute to this association, but distinct causal mechanisms remain to be defined. Some of these comorbid conditions may improve by periodontal treatment, and a bidirectional relationship may exist, where, for example, treatment of diabetes can improve periodontal status. The present article presents an overview of the evidence linking periodontitis with selected systemic diseases and calls for increased cooperation between dentists and medical doctors to provide optimal screening, treatment, and prevention of both periodontitis and its comorbidities.

An intravital microscopy model to study early pancreatic inflammation in type 1 diabetes in NOD mice

Intravital microscopy (IVM) of the pancreas has been proven to be an invaluable tool in pancreatitis, transplantation and ischemia/reperfusion research. Also in type 1 diabetes (T1D) pancreatic IVM offers unique advantages for the elucidation of the disease process. Female non-obese diabetic (NOD) mice develop T1D spontaneously by 40 weeks of age. Our goal was to establish an IVM-based method to study early pancreatic inflammation in NOD mice, which can be used to screen novel medications to prevent or delay T1D in future studies. This included evaluation of leukocyte-endothelial interactions as well as disturbances of capillary perfusion in the pancreatic microcirculation.

A review of the evidence for pathogenic mechanisms that may link periodontitis and diabetes

AIMS

To review the evidence for the molecular and cellular processes that may potentially link periodontal disease and diabetes. The pathogenic roles of cytokines and metabolic molecules (e.g. glucose, lipids) are explored and the role of periodontal bacteria is also addressed. Paradigms for bidirectional relationships between periodontitis and diabetes are discussed and opportunities for elaborating these models are considered.

METHODS

Database searches were performed using MeSH terms, keywords, and title words. Studies were evaluated and summarized in a narrative review.

RESULTS

Periodontal microbiota appears unaltered by diabetes and there is little evidence that it may influence glycaemic control. Small-scale clinical studies and experiments in animal models suggest that IL-1β, TNF-α, IL-6, OPG and RANKL may mediate periodontitis in diabetes. The AGE-RAGE axis is likely an important pathway of tissue destruction and impaired repair in diabetes-associated periodontitis. A role for locally activated pro-inflammatory factors in the periodontium, which subsequently impact on diabetes, remains speculative.

CONCLUSION

There is substantial information on potential mechanistic pathways which support a close association between diabetes and periodontitis, but there is a real need for longitudinal clinical studies using larger patient groups, integrated with studies of animal models and cells/tissues in vitro.

Lack of p47(phox) in Akita Diabetic Mice Is Associated with Interstitial Pneumonia, Fibrosis, and Oral Inflammation

Excess reactive oxygen species production is central to the development of diabetic complications. The contribution of leukocyte reactive oxygen species produced by the NADPH oxidase to altered inflammatory responses associated with uncontrolled hyperglycemia is poorly understood. To get insight into the role of phagocytic superoxide in the onset of diabetic complications, we used a model of periodontitis in mice with chronic hyperglycemia and lack of leukocyte p47(phox) (Akita/Ncf1) bred from C57BL/6-Ins2(Akita)/J (Akita) and neutrophil cytosolic factor 1 knockout (Ncf1) mice. Akita/Nfc1 mice showed progressive cachexia starting at early age and increased mortality by six months. Their lungs developed infiltrative interstitial lesions that obliterated air spaces as early as 12 weeks when fungal colonization of lungs also was observed. Neutrophils of Akita/Ncf1 mice had normal degranulation and phagocytic efficiency when compared with wild-type mice. Although Akita/Ncf1 mice had increased prevalence of oral infections and more severe periodontitis compared with wild-type mice, bone loss was only marginally higher compared with Akita and Ncf1 null mice. Altogether these results indicate that lack of leukocyte superoxide production in mice with chronic hyperglycemia results in interstitial pneumonia and increased susceptibility to infections.

Management of diabolical diabetes mellitus and periodontitis nexus: Are we doing enough?

Periodontitis is the commonest oral disease affecting population worldwide. This disease is notorious for the devastation of tooth supporting structures, ensuing in the loss of dentition. The etiology for this disease is bacterial biofilm, which accumulates on the teeth as dental plaque. In addition to the biofilm microorganisms, other factors such as environmental, systemic and genetic are also responsible in progression of periodontitis. Diabetes mellitus (DM) is metabolic disorder which has an impact on the global health. DM plays a crucial role in the pathogenesis of periodontitis. Periodontitis is declared as the “sixth” major complication of DM. Evidence based literature has depicted an enhanced incidence and severity of periodontitis in subjects with DM. A “two way” relationship has been purported between periodontitis and DM. Mutual management of both conditions is necessary. Periodontal therapy (PT) may assist to diminish the progression of DM and improve glycemic control. Various advanced technological facilities may be utilized for the purpose of patient education and disease management. The present paper clarifies the etio-pathogenesis of periodontitis, establishing it as a complication of DM and elaborating the various mechanisms involved in the pathogenesis. The role of PT in amelioration of DM and application of digital communication will be discussed. Overall, it is judicious to create an increased patient cognizance of the periodontitis-DM relationship. Conjunctive efforts must be undertaken by the medical and oral health care professionals for the management of periodontitis affected DM patients.

Interleukin-17A Gene Variability in Patients with Type 1 Diabetes Mellitus and Chronic Periodontitis: Its Correlation with IL-17 Levels and the Occurrence of Periodontopathic Bacteria

Interleukin-17 contributes to the pathogenesis of type 1 diabetes mellitus (T1DM) and chronic periodontitis (CP). We analyzed IL-17A -197A/G and IL-17F +7488C/T polymorphisms in T1DM and CP and determined their associations with IL-17 production and occurrence of periopathogens. Totally 154 controls, 125 T1DM, and 244 CP patients were genotyped using 5' nuclease TaqMan(®) assays. Bacterial colonization was investigated by a DNA-microarray kit. Production of IL-17 after in vitro stimulation of mononuclear cells by mitogens and bacteria was examined by the Luminex system. Although no differences in the allele/genotype frequencies between patients with CP and T1DM + CP were found, the IL-17A -197 A allele increased the risk of T1DM (P < 0.05). Levels of HbA1c were significantly elevated in carriers of the A allele in T1DM patients (P < 0.05). Production of IL-17 by mononuclear cells of CP patients (unstimulated/stimulated by Porphyromonas gingivalis) was associated with IL-17A A allele (P < 0.05). IL-17A polymorphism increased the number of Tannerella forsythia and Treponema denticola in patients with CP and T1DM + CP, respectively (P < 0.05). IL-17A gene variability may influence control of T1DM and the "red complex" bacteria occurrence in patients with CP and T1DM + CP. Our findings demonstrated the functional relevance of the IL-17A polymorphism with higher IL-17 secretion in individuals with A allele.

Comparison of Experimental Diabetic Periodontitis Induced by Porphyromonas gingivalis in Mice

Periodontitis is one of the severe complications in diabetic patients and gingival epithelium plays an initial role on the onset and progression of this disease. However the potential mechanism is yet sufficiently understood. Meanwhile, the research on the correlational experimental animal models was also insufficient. Here, we established periodontitis with type 2 diabetes in db/db and Tallyho/JngJ (TH) mice and periodontitis with type 1 diabetes in streptozotocin induced diabetes C57BL/6J (STZ-C57) mice by oral infection of periodontal pathogen Porphyromonas gingivalis W50. We demonstrated that periodontal infected mice with high blood glucose levels showed dramatically more alveolar bone loss than their counterparts, in which infected db/db mice exhibited the most bone defects. No contrary impact could be observed between this periodontal infection and onset and severity of diabetes. The expressions of PTPN2 were inhibited whereas the expression of JAK1, STAT1, and STAT3 increased dramatically in gingival epithelia and the serum TNF-α also significantly increased in the mice with diabetic periodontitis. Our results indicated that the variations of inflammation-related protein expressions in gingival epithelia might lead to the phenotype differences in the mice with diabetic periodontitis.

Therapeutic Targets for Management of Periodontitis and Diabetes

The increasing incidence of diabetes mellitus (DM) and chronic periodontitis (CP) worldwide imposes a rethinking of individualized therapy for patients with both conditions. Central to bidirectional links between DM and CP is deregulated systemic inflammation and dysfunctional immune responses to altered-self and non-self. Control of blood glucose levels and metabolic imbalances associated with hyperglycemia in DM, and disruption of pathogenic subgingival biofilms in CP are currently the main therapeutic approaches for these conditions. Mounting evidence suggests the need to integrate immune modulatory therapeutics in treatment regimens that address the unresolved inflammation associated with DM and CP. The current review discusses the pathogenesis of DM and CP with emphasis on deregulated inflammation, current therapeutic approaches and the novel pro-resolution lipid mediators derived from Ω-3 polyunsaturated fatty acids.

Ethical guidelines, animal profile, various animal models used in periodontal research with alternatives and future perspectives

Laboratory animal models serve as a facilitator to investigate the etiopathogenesis of periodontal disease, are used to know the efficacy of reconstructive and regenerative procedures, and are also helpful in evaluation of newer therapeutic techniques including laser and implant therapies prior to application in the human beings. The aim of this review is to know the different animal models used in various specialties of dental research and to know the ethical guidelines prior to the usage of experimental models with main emphasis on how to refine, replace, and reduce the number of animal models usage in the laboratory. An online search for experimental animal models used in dental research was performed using MEDLINE/PubMed database. Publications from 2009 to May 2013 in the specialty of periodontics were included in writing this review. A total of 652 references were published in PubMed/MEDLINE databases based on the search terms used. Out of 245 studies, 241 were related to the periodontal research published in English from 2009 to 2013. Relevant papers were chosen according to the inclusion and exclusion criteria. After extensive electronic and hand search on animal models, it has been observed that various animal models were used in dental research. Search on animal models used for dental research purpose revealed that various animals such as rats, mice, guinea pigs, rabbit, beagle dogs, goats, and nonhuman primates were extensively used. However, with the new advancement of ex vivo animal models, it has become easy to investigate disease pathogenesis and to test the efficacy of newer therapeutic modalities with the reduced usage of animal models. This review summarized the large amount of literature on animal models used in periodontal research with main emphasis on ethical guidelines and on reducing the animal model usage in future perspective.

Neutrophil homeostasis and inflammation: novel paradigms from studying periodontitis

Once viewed as simply antibacterial effector cells packed with antimicrobials, neutrophils are now increasingly appreciated for their regulatory roles in immunity and inflammation. The homeostatic regulation of neutrophils is thus crucial for optimal operation of the immune system. An attractive model to understand mechanistically the role of neutrophils is periodontitis, an oral inflammatory disease that is particularly sensitive to neutrophil alterations in numbers or function. The recruitment and proper activation of neutrophils are largely dependent on leukocyte integrins and complement. This review discusses how these processes are affected by host genetic or microbial factors leading to the development of periodontitis. For instance, both hypo- and hyper-recruitment of neutrophils as a result of deficiencies in the expression of β2 integrins or their negative regulators, respectively, causes unwarranted IL-17-dependent inflammatory bone loss. Moreover, microbial hijacking of C5aR (CD88) signaling in neutrophils impairs their antimicrobial function while promoting destructive inflammatory responses. These studies not only support the concept that neutrophil homeostasis is key to periodontal health but also reveal promising, new therapeutic targets as discussed in the review.

Relationship of clinical and microbiological variables in patients with type 1 diabetes mellitus and periodontitis

BACKGROUND

The aim of the study was to analyze how metabolic control of type 1 diabetes is related to clinical and microbiological periodontal parameters.

MATERIAL AND METHODS

The study involved 56 subjects aged from 19 to 50 years divided into 2 groups: healthy subjects (the H group), and diabetic (type 1 diabetes) patients with chronic untreated generalized periodontitis (the DM group). The glycosylated hemoglobin value (HbA1c) was determined using the UniCel DxC 800 SYNCHRON System (Beckman Coulter, USA), and the concentration in blood was measured by the turbidimetric immunoinhibition method. A molecular genetic assay (Micro-IDent plus, Germany) was used to detect periodontopathogenic bacteria in plaque samples. Periodontitis was confirmed by clinical and radiological examination.

RESULTS

Fusobacterium nucleatum, Capnocytophaga species, and Eikenella corrodens were the most frequently found bacteria in dental plaque samples (77.8%, 66.7%, and 33.4%, respectively), whereas Aggregatibacter actinomycetemcomitans was identified 40.7% less frequently in the DM group than in the H group. The strongest relationship was observed between the presence of 2 periodontal pathogens - F. nucleatum and Capnocytophaga spp. - and poorer metabolic control in type 1 diabetes patients (HbA1c) and all clinical parameters of periodontal pathology.

CONCLUSIONS

Periodontal disease was more evident in type 1 diabetic patients, and the prevalence of periodontitis was greatly increased in subjects with poorer metabolic control.

Role of insulin sensitivity and beta cell function in the development of periodontal disease in adults without diabetes

AIM

The goal of this study was to explore whether insulin resistance and beta cell function are related to periodontal pocket formation, indicative of infectious periodontal disease in non-smoking adults without manifest diabetes.

MATERIAL AND METHODS

We analysed data from a Health 2000 Survey consisting of dentate subjects without any indication of diabetes, aged between 30 and 64, who had never smoked and who had participated in the Follow-up Study on Finnish Adults' Oral Health about 4 years later (n = 157). The Homeostasis Model Assessment Indices were used to measure insulin resistance (HOMA-IR) and β-cell function (HOMA-B). The development of periodontal disease was measured by means of the incidence of deepened periodontal pockets (4 mm deep or deeper) during the follow-up period. Incidence rate ratios (IRR) were estimated using Poisson regression models.

RESULTS

Both HOMA-IR and HOMA-B indices were associated with periodontal pocket formation during the 4-year follow-up.

CONCLUSION

The results of this follow-up study suggest that impaired glucose metabolism measured as insulin resistance and altered beta cell function predict the breakdown of periodontal tissues. Further studies about their role in the pathogenesis of periodontal diseases are needed.

Global metabolomic analysis of human saliva and plasma from healthy and diabetic subjects, with and without periodontal disease

Recent studies suggest that periodontal disease and type 2 diabetes mellitus are bi-directionally associated. Identification of a molecular signature for periodontitis using unbiased metabolic profiling could allow identification of biomarkers to assist in the diagnosis and monitoring of both diabetes and periodontal disease. This cross-sectional study identified plasma and salivary metabolic products associated with periodontitis and/or diabetes in order to discover biomarkers that may differentiate or demonstrate an interaction of these diseases. Saliva and plasma samples were analyzed from 161 diabetic and non-diabetic human subjects with a healthy periodontium, gingivitis and periodontitis. Metabolite profiling was performed using Metabolon's platform technology. A total of 772 metabolites were found in plasma and 475 in saliva. Diabetics had significantly higher levels of glucose and α-hydroxybutyrate, the established markers of diabetes, for all periodontal groups of subjects. Comparison of healthy, gingivitis and periodontitis saliva samples within the non-diabetic group confirmed findings from previous studies that included increased levels of markers of cellular energetic stress, increased purine degradation and glutathione metabolism through increased levels of oxidized glutathione and cysteine-glutathione disulfide, markers of oxidative stress, including increased purine degradation metabolites (e.g. guanosine and inosine), increased amino acid levels suggesting protein degradation, and increased ω-3 (docosapentaenoate) and ω-6 fatty acid (linoleate and arachidonate) signatures. Differences in saliva between diabetic and non-diabetic cohorts showed altered signatures of carbohydrate, lipid and oxidative stress exist in the diabetic samples. Global untargeted metabolic profiling of human saliva in diabetics replicated the metabolite signature of periodontal disease progression in non-diabetic patients and revealed unique metabolic signatures associated with periodontal disease in diabetics. The metabolites identified in this study that discriminated the periodontal groups may be useful for developing diagnostics and therapeutics tailored to the diabetic population.

Risk factors for periodontal disease

Risk factors play an important role in an individual's response to periodontal infection. Identification of these risk factors helps to target patients for prevention and treatment, with modification of risk factors critical to the control of periodontal disease. Shifts in our understanding of periodontal disease prevalence, and advances in scientific methodology and statistical analysis in the last few decades, have allowed identification of several major systemic risk factors for periodontal disease. The first change in our thinking was the understanding that periodontal disease is not universal, but that severe forms are found only in a portion of the adult population who show abnormal susceptibility. Analysis of risk factors and the ability to statistically adjust and stratify populations to eliminate the effects of confounding factors have allowed identification of independent risk factors. These independent but modifiable, risk factors for periodontal disease include lifestyle factors, such as smoking and alcohol consumption. They also include diseases and unhealthy conditions such as diabetes mellitus, obesity, metabolic syndrome, osteoporosis, and low dietary calcium and vitamin D. These risk factors are modifiable and their management is a major component of the contemporary care of many periodontal patients. Genetic factors also play a role in periodontal disease and allow one to target individuals for prevention and early detection. The role of genetic factors in aggressive periodontitis is clear. However, although genetic factors (i.e., specific genes) are strongly suspected to have an association with chronic adult periodontitis, there is as yet no clear evidence for this in the general population. It is important to pursue efforts to identify genetic factors associated with chronic periodontitis because such factors have potential in identifying patients who have a high susceptibility for development of this disease. Many of the systemic risk factors for periodontal disease, such as smoking, diabetes and obesity, and osteoporosis in postmenopausal women, are relatively common and can be expected to affect most patients with periodontal disease seen in clinics and dental practices. Hence, risk factor identification and management has become a key component of care for periodontal patients.

Evaluation of adjunctive systemic doxycycline with non-surgical periodontal therapy within type 2 diabetic patients

OBJECTIVES

To evaluate the effects of systemic doxycycline on clinical and microbiological parameters of diabetic subjects with chronic periodontitis.

METHODS

This 9-month multi-center, randomized, parallel, single-blinded study was conducted from different hospitals in Riyadh, Saudi Arabia between April 2010 and December 2010. A total of 76 diabetic subjects with chronic periodontitis were randomized into 2 groups: control group (CG) received only scaling and root planing (SRP), and the treatment group (TG) receiving systemic doxycycline during the reevaluation visit 45 days after the completion of SRP. Probing pocket depth, clinical attachment level, gingival index, plaque index, and bleeding on probing were collected at baseline, 45 days after SRP, and one, 3, and 6 months  after the use of systemic doxycycline. Microbiological analysis comprised the detection of Tannerella forsythia (Tf), Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), and Prevotella intermedia (Pi) by polymerase chain reaction method.

RESULTS

Sixty-eight (33 CG and 35 TG) subjects completed the study. Greater reduction in the population of Tf, Pg, and Pi were observed in TG compared with CG in the first month after the administration of systemic doxycycline. The TG showed a significant improvement in gingival index scores compared with the CG (p&lt;0.05) by the end of the first and 6 months after the administration of doxycycline.

CONCLUSION

Adjunct systemic doxycycline can be associated with a reduction of Tf, Pg, and Pi in the first month after the administration of doxycycline with an improvement in the GI. 

High-dose atorvastatin reduces periodontal inflammation: a novel pleiotropic effect of statins

OBJECTIVES

The purpose of this study was to test whether high-dose statin treatment would result in a reduction in periodontal inflammation as assessed by (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT).

BACKGROUND

Periodontal disease (PD) is an independent risk factor for atherosclerosis.

METHODS

Eighty-three adults with risk factors or with established atherosclerosis and who were not taking high-dose statins were randomized to atorvastatin 80 mg vs. 10 mg in a multicenter, double-blind trial to evaluate the impact of atorvastatin on arterial inflammation. Subjects were evaluated using FDG-PET/CT at baseline and at 4 and 12 weeks. Arterial and periodontal tracer activity was assessed while blinded to treatment allocation, clinical characteristics, and temporal sequence. Periodontal bone loss (an index of PD severity) was evaluated using contrast-enhanced CT images while blinded to clinical and imaging data.

RESULTS

Seventy-one subjects completed the study, and 59 provided periodontal images for analysis. At baseline, areas of severe PD had higher target-to-background ratio (TBR) compared with areas without severe PD (mean TBR: 3.83 [95% confidence interval (CI): 3.36 to 4.30] vs. 3.18 [95% CI: 2.91 to 3.44], p = 0.004). After 12 weeks, there was a significant reduction in periodontal inflammation in patients randomized to atorvastatin 80 mg vs. 10 mg (ΔTBR 80 mg vs. 10 mg group: mean -0.43 [95% CI: -0.83 to -0.02], p = 0.04). Between-group differences were greater in patients with higher periodontal inflammation at baseline (mean -0.74 [95% CI: -1.29 to -0.19], p = 0.01) and in patients with severe bone loss at baseline (-0.61 [95% CI: -1.16 to -0.054], p = 0.03). Furthermore, the changes in periodontal inflammation correlated with changes in carotid inflammation (R = 0.61, p < 0.001).

CONCLUSIONS

High-dose atorvastatin reduces periodontal inflammation, suggesting a newly recognized effect of statins. Given the concomitant changes observed in periodontal and arterial inflammation, these data raise the possibility that a portion of that beneficial impact of statins on atherosclerosis relate to reductions in extra-arterial inflammation, for example, periodontitis. (Evaluate the Utility of 18FDG-PET as a Tool to Quantify Atherosclerotic Plaque; NCT00703261).

Periodontitis: oral complication of diabetes

Periodontitis is a common, chronic, inflammatory disease in which the supporting apparatus of the teeth is gradually destroyed, resulting in tooth mobility and tooth loss. Susceptibility to periodontitis is increased approximately three-fold in people with diabetes. Hyperglycemia leads to exacerbated tissue destruction and the clinical signs of periodontitis. There is evidence to support a two-way relationship between periodontitis and diabetes; not only does diabetes increase the risk for periodontitis, but periodontitis is associated with compromised glycemic control. Cooperation between health care teams would benefit the treatment of patients with diabetes and periodontitis.

Diabetes mellitus and periodontal diseases

A bidirectional relationship between diabetes mellitus (DM) and periodontal diseases (PDs) has been established. It is estimated that patients with poorly controlled DM are 3 times more likely to develop chronic PD compared with normoglycemic individuals despite similar composition in subgingival biofilms. Furthermore, these patients present with increased severity and rapid progression of attachment loss around teeth resulting in edentulism. Treatment of PD results in a modest but significant improvement in glycemic control in patients with DM reflected by a 0.4 % reduction in HbA1c-glycated hemoglobin levels. Compelling evidence from in vitro and animal studies supports a plausible biological explanation for the relationship between the 2 conditions centered on systemic low-grade inflammation. However, the limited number of comparable large randomized clinical trials is reflected in the limited specific guidelines offered by the international organizations for DM and PD regarding the management of the 2 diseases in an individual.

25-hydroxyvitamin D3 ameliorates periodontitis by modulating the expression of inflammation-associated factors in diabetic mice

Periodontitis is a complication of diabetes mellitus, and the two diseases are highly associated with the dysfunction of inflammatory mediators. 25-hydroxyvitamin D(3) (25(OH)D(3)) plays a pivotal role in inflammatory modulation, but little is known about its effects on the progression of diabetic periodontitis and the underlying mechanism. In this paper, we showed that 25(OH)D(3) ameliorated experimental periodontitis in diabetic mice. The intraperitoneal administration of 25(OH)D(3) to streptozotocin-induced diabetic mice reduced fasting glucose and serum TNF-α levels, leading to decreased alveolar bone loss. Western blot analyses of gingival epithelia showed that vitamin D receptor (VDR) and protein tyrosine phosphatase N2 (PTPN2) were upregulated, while the expression of NF-κB and the phosphorylation of Janus family kinase 1 (JAK1) were attenuated upon 25(OH)D(3) treatment. These data may provide an explanation for the therapeutic benefits and anti-inflammatory effects of 25(OH)D(3). Our findings should have important implications for the clinical therapy of diabetic periodontitis.

Experimental periodontitis induced by Porphyromonas gingivalis does not alter the onset or severity of diabetes in mice

BACKGROUND AND OBJECTIVE

Diabetes mellitus is believed to increase the risk and severity of periodontitis. However, less evidence is available on the converse effects of periodontitis on diabetes. The objective of the study was to investigate to what degree experimental periodontitis induced by Porphyromonas gingivalis might influence the onset and severity of diabetes in different mouse models.

MATERIAL AND METHODS

Twenty-eight male Tallyho/JngJ mice (type 2 diabetes), 20 male streptozotocin-induced diabetes C57BL/6J mice (type 1 diabetes) and 20 male C57BL/6J mice at 4 wks of age were evenly divided into two groups: periodontal infection and sham infection. Periodontitis was induced by Porphyromonas gingivalis W50 (P. gingivalis) oral inoculation before the development of diabetes. Sham-infected mice received vehicle as control. P. gingivalis in the oral cavity were identified by quantitative polymerase chain reaction. Fasting glucose, body weight and food intake levels were monitored and glucose tolerance tests were performed to assess glucose homeostasis for the onset and progression of diabetes. The level of alveolar bone loss and tumor necrosis factor-alpha were determined in week 20 when mice were killed.

RESULTS

Mice in the infection groups developed more alveolar bone loss than those in sham-infection groups (Tallyho p = 0.021; C57-STZ p = 0.014; C57 p = 0.035). Hyperglycemic mice exhibited significantly more bone loss compared to those normal glucose mice (Tallyho vs. C57 p = 0.029; C57-STZ vs. C57 p = 0.024). The level of tumor necrosis factor-alpha was consistent with that of periodontal bone loss and hyperglycemia. There was no significant effect of mouse species on the amount of bone loss at the same level of blood glucose. No statistically significant difference or trend in glucose metabolism was found between the infection and sham-infection group.

CONCLUSION

Diabetes enhanced the risk for periodontal disease induced by P. gingivalis. However, no converse impact was found between this periodontal infection and onset and severity of diabetes in both type 1 and 2 diabetes mice.

Efficacy of short-term adjunctive subantimicrobial dose doxycycline in diabetic patients--randomized study

OBJECTIVE

To investigate the effectiveness of short-term adjunctive subantimicrobial dose doxycycline (SDD) treatment in patients with diabetes mellitus type 2 and chronic periodontitis (CP).

METHODS

Thirty-four patients with CP and type 2 diabetes mellitus were included in the placebo-controlled, double-blind study. After scaling and root planing (SRP), patients were randomly assigned to two groups, receiving either SDD or placebo bid for 3 months. The probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), approximal plaque index, glycated hemoglobin (HbA1c) level were recorded and gingival crevicular fluid (GCF) samples were collected at baseline and after 3-month therapy for the estimation of matrix metalloproteinase-8 levels.

RESULTS

Clinical attachment level, PD, and BOP improved significantly in both groups after therapy (P < 0.05). The statistically significant difference between the two groups after the therapy was observed only in PD in tooth sites with initial PD ≥ 4 mm (SRP + placebo: 3.41 ± 0.6 mm vs SRP + SDD: 2.92 ± 0.5 mm, P < 0.05). GCF matrix metalloproteinase-8 levels were significantly reduced only in SRP + SDD group (P < 0.01). There were no changes in HbA1c levels after therapy.

CONCLUSION

The short-term administration of SDD gives significant benefit at tooth sites with moderate disease (PD ≥ 4 mm) when compared to SRP alone in patients with diabetes and CP.

Spontaneous periodontitis development in diabetic rats involves an unrestricted expression of inflammatory cytokines and tissue destructive factors in the absence of major changes in commensal oral microbiota

Diabetes mellitus is a heterogeneous group of disorders, in which hyperglycemia is a main feature. The objective was to evaluate the involvement of RAGE, inflammatory cytokines, and metalloproteinases in spontaneous periodontitis triggered by diabetes induction. Immunohistochemical procedures for MMP-2, MMP-9, TNF-α, IL-1β, IL-6, RANKL, and RAGE were performed in rats after 1, 3, 6, 9, and 12 months of diabetes induction. Total DNA was extracted from paraffin-embedded tissues and evaluated by Real-TimePCR for 16S total bacterial load and specific periodontopathogens. Our data did not demonstrate differences in microbiological patterns between groups. In diabetic groups, an increase in RAGE-positive cells was detected at 6, 9, and 12 months, while TNF-alpha-stained cells were more prevalent at 6 and 12 months. In experimental groups, IL-β-positive cells were increased after 12 months, IL-6 stained cells were increased at 9 and 12 months, and RANKL-positive cells at 9 months. Diabetes resulted in widespread expression of RAGE, followed by expression of proinflammatory mediators, without major alterations in oral microbial profile. The pervasive expression of cytokines suggests that spontaneous periodontitis development may be independent of microbial stimulation and may be triggered by diabetes-driven imbalance of homeostasis.

Inflammatory biomarkers in saliva: assessing the strength of association of diabetes mellitus and periodontal status with the oral inflammatory burden

AIM

To determine the strength of association of type 2 diabetes mellitus and periodontal disease with the oral inflammatory burden, as assessed by markers of inflammation in saliva.

MATERIAL AND METHODS

Unstimulated saliva samples were collected from 192 subjects with or without type 2 diabetes. β-glucuronidase (βG) was measured via a fluorometric array and interlukin-1β (IL-1β) via enzyme-linked immunosorbent assay. The concentration of both mediators was evaluated in relationship to clinical parameters, severity of periodontal disease and diabetes status.

RESULTS

Regression analysis demonstrated that diabetes and periodontal disease was independently and positively correlated with increased concentration of βG in saliva (p < 0.001). Moreover, the relative association of periodontal disease with the level of βG in saliva was greater than the strength of association of the diabetic status. IL-1β concentration in saliva was primarily associated with the severity of periodontal disease (p < 0.01), but not the presence of diabetes (p = 0.50).

CONCLUSIONS

This study examined the nature of the inflammatory response in the oral cavity as assessed by inflammatory markers in saliva. Both periodontal disease and diabetes mellitus were independently associated with the oral inflammatory burden, in which the effect of periodontal disease was more pronounced.

The diabetic patient and dental treatment: an update

This paper has been written to both refresh and update clinicians' knowledge of diabetes. Treatment for patients with diabetes continues to develop with the majority of Type 1 diabetics now using multiple daily injections and an increasing minority using insulin pumps. Blood glucose monitoring and patient education programmes have resulted in more patient involvement in controlling this condition. Type 2 diabetics have had improvement in care provision through the development of shorter acting sulphonylureas and the potential for GLP1 injections. The impact of diabetes on both oral health and quality of life is discussed. Practical suggestions are made regarding the dental treatment of diabetic patients using both local anaesthetic and under sedation. Diabetes continues to be a fickle master for those affected by this condition. The paper is written from the perspective of the 'expert patient'. It is hoped that a greater understanding of this chronic condition will improve both access to, and safety of, dental care for those patients with diabetes.

Diabetes mellitus and periodontitis: a tale of two common interrelated diseases

Diabetes mellitus (a group of metabolic disorders characterized by hyperglycemia) and periodontitis (a microbially induced inflammatory disorder that affects the supporting structures of teeth) are both common, chronic conditions. Multiple studies have demonstrated that diabetes mellitus (type 1 and type 2) is an established risk factor for periodontitis. Findings from mechanistic studies indicate that diabetes mellitus leads to a hyperinflammatory response to the periodontal microbiota and also impairs resolution of inflammation and repair, which leads to accelerated periodontal destruction. The cell surface receptor for advanced glycation end products and its ligands are expressed in the periodontium of individuals with diabetes mellitus and seem to mediate these processes. The association between the two diseases is bidirectional, as periodontitis has been reported to adversely affect glycemic control in patients with diabetes mellitus and to contribute to the development of diabetic complications. In addition, meta-analyses conclude that periodontal therapy in individuals with diabetes mellitus can result in a modest improvement of glycemic control. The effect of periodontal infections on diabetes mellitus is potentially explained by the resulting increase in levels of systemic proinflammatory mediators, which exacerbates insulin resistance. As our understanding of the relationship between diabetes mellitus and periodontitis deepens, increased patient awareness of the link between diabetes mellitus and oral health and collaboration among medical and dental professionals for the management of affected individuals become increasingly important.