Periodontal diseases in the United States population

Effects of aging on endotoxin tolerance induced by lipopolysaccharides derived from Porphyromonas gingivalis and Escherichia coli

BACKGROUND

Periodontitis is a bacterially induced chronic inflammatory disease. Exposure of the host to periodontal pathogens and their virulence factors induces a state of hyporesponsiveness to subsequent stimulations, termed endotoxin tolerance. Aging has a profound effect on immune response to bacteria challenge. The aim of this study was to explore the effects of aging on endotoxin tolerance induced by Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) and Escherichia coli (E. coli) LPS in murine peritoneal macrophages.

METHODOLOGY/PRINCIPAL FINDINGS

We studied the cytokine production (TNF-α and IL-10) and Toll-like receptor 2, 4 (TLR2, 4) gene and protein expressions in peritoneal macrophages from young (2-month-old) and middle-aged (12-month-old) ICR mice following single or repeated P. gingivalis LPS or E. coli LPS stimulation. Pretreatment of peritoneal macrophages with P. gingivalis LPS or E. coli LPS resulted in a reduction in TNF-α production and an increase in IL-10 production upon secondary stimulation (p<0.05), and the markedly lower levels of TNF-α and higher levels of IL-10 were observed in macrophages from young mice compared with those from middle-aged mice (p<0.05). In addition, LPS restimulations also led to the significantly lower expression levels of TLR2, 4 mRNA and protein in macrophages from young mice (p<0.05).

CONCLUSIONS/SIGNIFICANCE

Repeated LPS stimulations triggered endotoxin tolerance in peritoneal macrophages and the ability to develop tolerance in young mice was more excellent. The impaired ability to develop endotoxin tolerance resulted from aging might be related to TLR2, 4 and might lead to the incontrollable periodontal inflammation in older adults.

Probiotic effects of orally administered Lactobacillus reuteri-containing tablets on the subgingival and salivary microbiota in patients with gingivitis. A randomized clinical trial

OBJECTIVE

To investigate the effects of an orally administered probiotic on the oral microbiota.

METHODS

A placebo-controlled, parallel study was conducted in 40 gingivitis subjects during 8 weeks. Treatment consisted on the administration of a daily tablet, either containing Lactobacillus reuteri or placebo. Unstimulated saliva and subgingival samples were collected and analysed by culture and PCR. Clinical and microbiological outcome variables were compared between and within groups.

RESULTS

There were no significant changes between and within the groups in the clinical variables. In saliva, total anaerobic counts after 4 weeks (p = 0.021) and counts of Prevotella intermedia after 8 weeks (p = 0.030), showed reductions in the test group. In subgingival samples, significant reductions in the changes baseline to 4 weeks were observed for P. gingivalis counts (p = 0.008). With PCR, L. reuteri ATCC-PTA-5289 was more frequently detected than L. reuteri DSM-17938.

CONCLUSIONS

The effect of L. reuteri administered in tablets resulted in a reduction in the number of selected periodontal pathogens in the subgingival microbiota, without an associated clinical impact.

Hypoxia induces apoptosis and autophagic cell death in human periodontal ligament cells through HIF-1α pathway

OBJECTIVES

Oxygen deficiency caused by occlusal trauma and smoking can be present in patients with periodontitis. However, biochemical events important in periodontal tissues during hypoxia remain unclear. The aim of this study was to investigate effects of hypoxia on apoptosis and autophagy of human periodontal ligament cells (PDLCs) in vitro.

MATERIALS AND METHODS

Human PDLCs were obtained and cultured in vitro. Cell viability, apoptosis, autophagy and gene and protein expression were measured in presence and absence of cobalt chloride (CoCl(2)).

RESULTS

CoCl(2) induced cytotoxicity of human PDLCs in a concentration-dependent manner dependent on macromolecular synthesis, and resulted in apoptosis and mitochondrial dysfunction. CoCl(2) also induced redistribution of autophagy marker LC3, increased ratio of LC3-IIto LC3-Iand function of lysosomes. Furthermore, CoCl(2) promoted expression of HIF-1α following upregulation of expressions of Bnip3. Significant increases in expression of IL-1β and MMP-8 were also observed. All these results were reversed by pre-treatment with antioxidant N-acetylcysteine.

CONCLUSIONS

Our data showed that CoCl(2) could induce cytotoxicity through mitochondria- apoptotic and autophagic pathways involved in HIF-1α. CoCl(2 -treated PDLCs may serve as an in vitro model for studies of molecular mechanisms in periodontitis.

A critical review of diabetes, glycemic control, and dental implant therapy

OBJECTIVES

To systematically examine the evidence guiding the use of implant therapy relative to glycemic control for patients with diabetes and to consider the potential for both implant therapy to support diabetes management and hyperglycemia to compromise implant integration.

MATERIAL AND METHODS

A systematic approach was used to identify and review clinical investigations directly assessing implant survival or failure for patients with diabetes. A MEDLINE (PubMED) database search identified potential articles for inclusion using the search strategy: (dental implants OR oral implants) AND (diabetes OR diabetic). Inclusion in this review required longitudinal assessments including at least 10 patients, with included articles assessed relative to documentation of glycemic status for patients.

RESULTS

Although the initial search identified 129 publications, this was reduced to 16, for inclusion. Reported implant failure rates for diabetic patients ranged from 0% to 14.3%. The identification and reporting of glycemic control was insufficient or lacking in 13 of the 16 studies with 11 of these enrolling only patients deemed as having acceptable glycemic control, limiting interpretation of findings relative to glycemic control. Three of the 16 studies having interpretable information on glycemic control failed to demonstrate a significant relationship between glycemic control and implant failure, with failure rates ranging from 0% to 2.9%.

CONCLUSIONS

Clinical evidence is lacking for the association of glycemic control with implant failure while support is emerging for implant therapy in diabetes patients with appropriate accommodations for delays in implant integration based on glycemic control. The role for implants to improve oral function in diabetes management and the effects of hyperglycemia on implant integration remain to be determined.

The association between inflammatory bowel disease and periodontitis among Jordanians: a case-control study

BACKGROUND AND OBJECTIVE

Inflammatory bowel disease (IBD) is hypothesized to involve immuno-inflammatory alterations, and the condition has been related to increased susceptibility to oral challenges. The objective of the study was to determine the association between the prevalence, severity and extent of periodontitis and both ulcerative colitis (UC) and Crohn's disease (CD).

MATERIAL AND METHODS

A case-control study was conducted among patients who attended outpatient clinics at King Hussein Medical City in Jordan during the study period. All participants completed the questionnaire and underwent thorough oral and periodontal examinations. Periodontitis was defined as presence of four or more teeth with one or more sites with probing pocket depth ≥ 4 mm and clinical attachment level ≥ 3 mm. The general linear model multivariate procedure and multivariate binary logistic regression were used to analyse the data.

RESULTS

This case-control study included 260 Jordanian adults (101 with UC, 59 with CD and 100 with no IBD) with a mean (SD) age of 39.4 (0.7) years. The prevalence of periodontitis was much higher among patients with CD and those with UC compared with subjects having no IBD in the age groups < 36 and 36-45 years old only. After adjusting for age and number of missing teeth, patients with CD (odds ratio 4.9, 95% confidence interval 1.8-13.2) and patients with UC (odds ratio 7.00, 95% confidence interval 2.8-17.5) had significantly higher odds of periodontitis than subjects with no IBD. In multivariate analysis, the severity of periodontitis was significantly higher among patients with CD and patients with UC when compared with subjects having no IBD. Ulcerative colitis patients but not CD patients had significantly higher prevalence of deep ulcers in oral soft tissues than the non-IBD group (p = 0.004).

CONCLUSION

Patients with IBD have higher prevalence, severity and extent of periodontitis compared with those having no IBD.

Quantitative determination of lysophosphatidic acids (LPAs) in human saliva and gingival crevicular fluid (GCF) by LC-MS/MS

Lysophosphatidic acid (LPA) is a phospholipid mediator that plays multiple cellular functions by acting through G protein-coupled LPA receptors. LPAs are known to be key mediators in inflammation, and several lines of evidence suggest a role for LPAs in inflammatory periodontal diseases. A simple and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method has been developed and validated to quantify LPA species (LPA 18:0, LPA 16:0, LPA 18:1 and LPA 20:4) in human saliva and gingival crevicular fluid (GCF). LPA 17:0 was used as an internal standard and the LPA species were extracted from saliva by liquid-liquid extraction using butanol. Chromatography was performed using a Macherey-Nagel NUCLEODUR® C8 Gravity Column (125 mm × 2.0 mm ID) with a mixture of methanol/water: 75/25 (v/v) containing 0.5% formic acid and 5 mM ammonium formate (mobile phase A) and methanol/water: 99/0.5 (v/v) containing 0.5% formic acid and 5mM ammonium formate (mobile phase B) at a flow rate of 0.5 mL/min. LPAs were detected by a linear ion trap-triple quadrupole mass spectrometer with a total run time of 8.5 min. The limit of quantification (LOQ) in saliva was 1 ng/mL for all LPA species and the method was validated over the range of 1-200 ng/mL. The method was validated in GCF over the ranges of 10-500 ng/mL for LPA 18:0 and LPA 16:0, and 5-500 ng/mL for LPA 18:1 and LPA 20:4. This sensitive LC-MS/MS assay was successfully applied to obtain quantitative data of individual LPA levels from control subjects and patients with various periodontal diseases. All four LPA species were consistently elevated in samples obtained from periodontal diseases, which supports a role of LPAs in the pathogenesis of periodontal diseases.

TLR2-dependent modulation of osteoclastogenesis by Porphyromonas gingivalis through differential induction of NFATc1 and NF-kappaB

Osteolytic diseases, including rheumatoid arthritis, osteomyelitis, and periodontitis, are usually associated with bacterial infections. However, the precise mechanisms by which bacteria induce bone loss still remain unclear. Evidence exists that Toll-like receptor (TLR) signaling regulates both inflammation and bone metabolism and that the receptor activator of NF-κB ligand (RANKL) and its receptor RANK are the key regulators for bone remodeling and for the activation of osteoclasts. Here, we investigate the direct effects of the periodontal pathogen Porphyromonas gingivalis on osteoclast differentiation and show that P. gingivalis differentially modulates RANKL-induced osteoclast formation contingent on the state of differentiation of osteoclast precursors. In addition, although an optimal induction of cytokines by P. gingivalis is dependent on TLR2 and TLR4, as well as myeloid differentiation factor 88 and Toll/IL-1R domain-containing adaptor-inducing IFN-β, P. gingivalis utilizes TLR2/ myeloid differentiation factor 88 in modulating osteoclast differentiation. P. gingivalis modulates RANKL-induced osteoclast formation by differential induction of NFATc1 and c-Fos. More importantly, RANKL-mediated lineage commitment also has an impact on P. gingivalis-induced cytokine production. RANKL inhibits P. gingivalis-induced cytokine production by down-regulation of TLR/NF-κB and up-regulation of NFATc1. Our findings reveal novel aspects of the interactions between TLR and RANK signaling and provide a new model for understanding the mechanism underlying the pathogenesis of bacteria-mediated bone loss.

A symmetrized Theil index measure of health disparities: An example using dental caries in U.S. children and adolescents

While the health status of Americans has generally improved over time, health disparities among groups of the population have been pervasive. Designing a measure that tracks the resulting disparities remains a challenge. In this paper, we propose a new measure of health disparities the Symmetrized Theil Index (STI), and derive its design-based sampling variance in grouped survey data. Because STI is symmetric, it circumvents the drawback of the Theil Index in how groups are weighted: indeed, the latter is mostly influenced by groups with high disease frequencies. Moreover, STI is related to Pearson's chi-square test of independence for binary data, and to the F-test in one-way analysis-of-variance for continuous data. We illustrate our approach using data on dental caries for children and adolescents from the third National Health and Nutrition Examination Surveys (NHANES III; 1988-1994) and NHANES 1999-2004. Tooth decay remains the most common chronic disease in U.S. children and adolescents. Although their oral health has generally improved, we find no change in the prevalence or severity of untreated tooth decay in U.S. children and adolescents between surveys. These findings are consistently observed for both the overall STI and its between-group component across gender, race/ethnicity, country of birth, survey respondent's education, income and poverty-income ratio.

Association between metabolic syndrome and periodontal disease

BACKGROUND

Metabolic syndrome has been suggested as a potential risk factor for periodontal disease. Data based on NHANES III, with 7431 subjects aged 20 years or older, were analysed to confirm the association between metabolic syndrome and periodontal disease, and identify which components of metabolic syndrome might play a role in this association.

METHODS

Clinical criteria for metabolic syndrome included: (1) abdominal obesity; (2) increased triglycerides; (3) decreased HDL cholesterol; (4) hypertension or current use of hypertension medication; and (5) high fasting plasma glucose. Periodontal disease was evaluated by probing pocket depth (PPD) and was defined as mean PPD≥2.5 mm.

RESULTS

Women with two or more metabolic components had significantly increased odds of having periodontal disease as compared to those with no component [(two components, OR=5.6 (95% CI: 2.2-14.4); three or more, OR=4.7 (2.0-11.2)]. Using the definition of metabolic syndrome as having three to five metabolic components (reference group with <3 components), the adjusted odds ratios were 1.0 (0.7-1.6) for men and 2.1 (1.2-3.7) for women. Abdominal obesity was the largest contributory factor in both genders.

CONCLUSIONS

While the association between metabolic syndrome and periodontal disease was particularly significant for women, abdominal obesity appeared to be the contributing metabolic factor for both genders.

Review: Pathogen-induced inflammation at sites distant from oral infection: bacterial persistence and induction of cell-specific innate immune inflammatory pathways

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.

Periodontal health status in the elderly with different levels of education: a 5-year follow-up study

OBJECTIVE

To assess the association between the periodontal health status and level of education over a 5-year period among the elderly aged 75 years and older.

BACKGROUND

Oral health among the higher educated is known to be better than among the less-well educated. On the other hand, the prevalence and severity of periodontal disease has been found to grow with increasing age.

METHODS

The participants were derived from a population-based Helsinki Aging Study, a random sample of 76-, 81- and 86-year-old elderly. The 170 dentate elderly who underwent clinical oral examinations at baseline and 71 who participated in the follow-up were included in this study. The data was collected from intraoral and radiological examinations and from a structured questionnaire.

RESULTS

Subjects with a higher level of education had more retained teeth than subjects with a lower level of education. According to CPITN index, better-educated participants had more healthy sextants, but they also had more sextants with periodontal pockets. Radiographic examination showed similar results.

CONCLUSION

Level of education has a clear effect on the periodontal health status in the elderly. More treatment need seems to polarise into those elderly who are better educated as they retain more teeth into old age.

Porphyromonas gingivalis cysteine proteinase inhibition by kappa-casein peptides

Porphyromonas gingivalis is a major pathogen associated with chronic periodontitis, an inflammatory disease of the supporting tissues of the teeth. The Arg-specific (RgpA/B) and Lys-specific (Kgp) cysteine proteinases of P. gingivalis are major virulence factors for the bacterium. In this study κ-casein(109-137) was identified in a chymosin digest of casein as an inhibiting peptide of the P. gingivalis proteinases. The peptide was synthesized and shown to inhibit proteolytic activity associated with P. gingivalis whole cells, purified RgpA-Kgp proteinase-adhesin complexes, and purified RgpB proteinase. The peptide κ-casein(109-137) exhibited synergism with Zn(II) against both Arg- and Lys-specific proteinases. The active region for inhibition was identified as κ-casein(117-137) using synthetic peptides. Kinetic studies revealed that κ-casein(109-137) inhibits in an uncompetitive manner. A molecular model based on the uncompetitive action and its synergistic ability with Zn(II) was developed to explain the mechanism of inhibition. Preincubation of P. gingivalis with κ-casein(109-137) significantly reduced lesion development in a murine model of infection.

Systemic consequences of poor oral health in chronic kidney disease patients

Changes in the oral cavity, such as periodontitis and other manifestations of poor oral health, are common in patients with chronic kidney disease (CKD) and may contribute to increased morbidity and mortality because of systemic consequences such as inflammation, infections, protein-energy wasting, and atherosclerotic complications. Poor oral health in CKD patients may thus represent an important, but often overlooked, problem. Several studies show that uremic patients have higher rates of decayed, missing, and filled teeth, loss of attachment, and periapical and mucosal lesions than the general population. The consequences of poor oral health may be more severe in CKD patients because of advanced age, common comorbidities such as diabetes, concurrent medications, and a state of immune dysfunction that may increase the risk for systemic consequences of periodontitis and other oral and dental pathologic conditions. Poor dentition and other signs of poor oral health should be an alarm clock also at early stages of CKD. However, it remains to be determined whether more successful management of poor oral health and periodontitis will reduce the risk of inflammation, infection, protein-energy wasting, and atherosclerotic complications in CKD patients. This review explores etiological factors and potential systemic consequences of poor oral health in CKD patients as well as possible preventive and therapeutic strategies.

Linear mixed models for skew-normal/independent bivariate responses with an application to periodontal disease

Bivariate clustered (correlated) data often encountered in epidemiological and clinical research are routinely analyzed under a linear mixed model (LMM) framework with underlying normality assumptions of the random effects and within-subject errors. However, such normality assumptions might be questionable if the data set particularly exhibits skewness and heavy tails. Using a Bayesian paradigm, we use the skew-normal/independent (SNI) distribution as a tool for modeling clustered data with bivariate non-normal responses in an LMM framework. The SNI distribution is an attractive class of asymmetric thick-tailed parametric structure which includes the skew-normal distribution as a special case. We assume that the random effects follow multivariate SNI distributions and the random errors follow SNI distributions which provides substantial robustness over the symmetric normal process in an LMM framework. Specific distributions obtained as special cases, viz. the skew-t, the skew-slash and the skew-contaminated normal distributions are compared, along with the default skew-normal density. The methodology is illustrated through an application to a real data which records the periodontal health status of an interesting population using periodontal pocket depth (PPD) and clinical attachment level (CAL).

Smokeless tobacco use and periodontal health in a rural male population

BACKGROUND

Despite the reported effects of smokeless tobacco (ST) on the periodontium and high prevalence of ST use in rural populations and in men, studies on this specific topic are limited. The purpose of this cross-sectional investigation is to evaluate the periodontal health status of male ST users from a rural population.

METHODS

Adult male residents of two rural Appalachian Ohio counties and daily ST users, with a unilateral mandibular oral ST keratosis lesion, were recruited. Subjects completed a questionnaire and received oral examination. Teeth present, ST keratosis lesion, plaque and gingival index, probing depth (PD), recession depth (RD), and attachment level were recorded. Statistical analysis compared ST-site mandibular teeth (teeth adjacent to the subject's unilateral ST keratosis lesion) to NST-site teeth (contralateral corresponding teeth).

RESULTS

This study includes 73 ST users. Recession prevalence is much greater in ST-site quadrants (36%) compared to NST-site quadrants (18%; P <0.001). Twice as many teeth had recession on ST-site (approximately 20%) than NST-site (approximately 10%; P = 0.0001). Average buccal RD on ST-site teeth did not differ from that on the NST-site teeth (P = 0.0875). Although average buccal attachment loss is greater on ST-site teeth (P = 0.016), the mean difference is <0.5 mm. When stratified by years of ST use, subjects using ST for 10 to 18 years exhibit the most differences between ST and NST sites, whereas subjects using ST for <10 years show no differences.

CONCLUSION

The results indicate that greater gingival recession prevalence and extent are associated with ST placement site in rural male ST users.

A prospective study of periodontal disease and risk of rheumatoid arthritis

OBJECTIVE

To test for an association between periodontal disease (PD) and incident rheumatoid arthritis (RA) in a large prospective cohort.

METHODS

We conducted a prospective analysis of history of periodontal surgery, tooth loss, and risk of RA among 81,132 women in the Nurses' Health Study prospective cohort. Periodontal surgery and tooth loss were used as proxies for history of PD. There were 292 incident RA cases diagnosed from 1992 to 2004. Information on periodontal surgery and tooth loss in the past 2 years was collected by questionnaire in 1992. Cox proportional hazards models were used to assess relationships between periodontal surgery, tooth loss, and risk of RA adjusting for age, smoking, number of natural teeth, body mass index, parity, breastfeeding, postmenopausal status, postmenopausal hormone use, father's occupation, and alcohol intake.

RESULTS

Compared with those who reported no history of periodontal surgery or tooth loss, women with periodontal surgery or tooth loss did not have a significantly elevated risk of RA in multivariable-adjusted models (RR 1.24, 95% CI 0.83, 1.83; and RR 1.18, 95% CI 0.47, 2.95, respectively). In analyses stratified by ever and never-smokers, ever-smokers with periodontal surgery had an increased risk that was also nonsignificant. Those with severe PD (both history of periodontal surgery and tooth loss) did not have a significant increased risk.

CONCLUSION

In this large cohort of American women, there was no evidence of an increased risk of later-onset RA among those with a history of periodontal surgery and/or tooth loss.

Review paper: DNA delivery strategies to promote periodontal regeneration

Periodontal diseases are caused by bacteria with an inflammatory component that result in the loss of bone and soft tissue around the neck of the teeth. Recent therapies allow clinicians to regenerate some of the lost structures of the periodontium. Regeneration of these lost supporting structures is a highly orchestrated process, involving various cellular and molecular players, leading to the complete restoration of the periodontium (the tooth-supporting apparatus). The introduction of growth factors has positively influenced the clinical outcome of the existing regenerative procedures but the supra-physiological doses and the high cost associated with these growth factors can be drawbacks. Gene therapy may offer some interesting advantages to current therapies. In the field of periodontology, several studies have been conducted to explore the efficacy of delivering the DNA of key growth factors using viral vectors in both periodontal and peri-implant bone regeneration. Relatively few studies have explored the application of nonviral gene therapy in periodontal regeneration. This article is aimed at reviewing the studies conducted so far using viral and nonviral gene delivery approaches to achieve periodontal and peri-implant bone regeneration.

Tetratricopeptide repeat protein-associated proteins contribute to the virulence of Porphyromonas gingivalis

Porphyromonas gingivalis is one of the most etiologically important microorganisms in periodontal disease. We found in a previous study that PG1385 (TprA) protein, a tetratricopeptide repeat (TPR) protein, was upregulated in P. gingivalis wild-type cells placed in a mouse subcutaneous chamber and that a tprA mutant was clearly less virulent in the mouse subcutaneous abscess model (M. Yoshimura et al., Oral Microbiol. Immunol. 23:413-418, 2008). In the present study, we investigated the gene expression profile of tprA mutant cells placed in a mouse subcutaneous chamber and found that 9 genes, including PG2102 (tapA), PG2101 (tapB), and PG2100 (tapC) genes, were downregulated in the tprA mutant compared with those in the wild type. Expression of a cluster of tapA, tapB, and tapC genes of the mutant was also downregulated in an in vitro culture with enriched brain heart infusion medium. The TprA protein has three TPR motifs known as a protein-protein interaction module. Yeast two-hybrid system analysis and in vitro protein binding assays with immunoprecipitation and surface plasmon resonance detection revealed that the TprA protein could bind to TapA and TapB proteins. TprA and TapB proteins were located in the periplasmic space, whereas TapA, which appeared to be one of the C-terminal domain family proteins, was located at the outer membrane. We constructed tapA, tapB, and tapC single mutants and a tapA-tapB-tapC deletion mutant. In the mouse subcutaneous infection experiment, all of the mutants were less virulent than the wild type. These results suggest that TprA, TapA, TapB, and TapC are cooperatively involved in P. gingivalis virulence.

A LATENT FACTOR MODEL FOR SPATIAL DATA WITH INFORMATIVE MISSINGNESS

A large amount of data is typically collected during a periodontal exam. Analyzing these data poses several challenges. Several types of measurements are taken at many locations throughout the mouth. These spatially-referenced data are a mix of binary and continuous responses, making joint modeling difficult. Also, most patients have missing teeth. Periodontal disease is a leading cause of tooth loss, so it is likely that the number and location of missing teeth informs about the patient's periodontal health. In this paper we develop a multivariate spatial framework for these data which jointly models the binary and continuous responses as a function of a single latent spatial process representing general periodontal health. We also use the latent spatial process to model the location of missing teeth. We show using simulated and real data that exploiting spatial associations and jointly modeling the responses and locations of missing teeth mitigates the problems presented by these data.

Characteristics of inflammation common to both diabetes and periodontitis: are predictive diagnosis and targeted preventive measures possible?

Diabetes and periodontitis are chronic inflammatory disorders that contribute to each others' severity and worsen each others' prognosis. Studies have shown that patients with diabetes are at increased risk of developing periodontitis, and that diabetics with untreated periodontitis have more difficulty controlling serum glucose. Periodontal treatment that reduces gingival inflammation aids in the control of hyperglycemia. Periodontitis is accompanied by gingival bleeding and the production of an inflammatory exudate termed gingival crevicular fluid (GCF) that arises from the inflamed gingival tissues surrounding the teeth. GCF contains byproducts of connective tissue degradation, enzymes from host and bacterial cells, cytokines and other inflammatory mediators, and has been studied for screening blood glucose and for biomarkers of both diabetes and periodontitis. This review focuses on the inter-relationship between diabetes and periodontitis and the biomarkers common to both these diseases that may enable earlier detection, targeted preventive measures and individualized therapeutic intervention of these chronic conditions.

Future approaches in periodontal regeneration: gene therapy, stem cells, and RNA interference

Periodontal disease is a major public health issue and the development of effective therapies to treat the disease and regenerate periodontal tissue is an important goal of today's medicine. This article highlights recent scientific advancements in gene therapy, stem cell biology, and RNA interference with the intent of identifying their potential in periodontal tissue regeneration. Results from basic research, preclinical, and clinical studies indicate that these fields of research may soon contribute to more effective regenerative therapies for periodontal disease.

Periodontal disease in mothers indicates risk in their children

INTRODUCTION

It is well established that severe periodontitis clusters in families, but there are no data about the relationship between mothers with chronic periodontitis and their children's periodontal status.

OBJECTIVE

To evaluate a risk for periodontal diseases in children of periodontally diseased and healthy mothers.

METHODS

Four study groups were included: (I) 20 female patients with untreated generalized severe chronic periodontitis, (II) their children (34), (III) 13 periodontally healthy mothers and (IV) their children (13). Material was collected from years 2004-2006. The clinical examination included registration of visible plaque index, modified gingival index and, bleeding sites on probing. Periodontal microbiological samples were obtained from all study subjects and the isolates were identified according to morphology and biochemical profiles; similar interfamilial pathogens were compared by PCR-technique.

RESULTS

The children of diseased mothers more frequently had periodontal diseases, especially gingivitis. In addition, clinical parameters of gingival inflammation were more expressed and oral hygiene was worse in this group of children. VPI and VPI% of the diseased and healthy mothers differed significantly. The most common oral pathogens were P. intermedia/nigrescens and A. actinomycetemcomitans. The children of healthy mothers harboured pathogens less frequently than the children of diseased mothers. The sharing of P. intermedia/nigrescens was more frequent (5 families) than A. actinomycetemcomitans (2 families).

CONCLUSION

Maternal indicators, such as periodontitis, hygiene habits, and periodontal microflora are risk factors for childhood periodontal diseases, and might be predictive of future childhood and adolescent periodontitis.

Inhibition of Porphyromonas gingivalis biofilm by oxantel

Porphyromonas gingivalis is a major pathogen of chronic periodontitis and exists in a biofilm on the surface of the tooth root. Oxantel, a cholinergic anthelmintic and fumarate reductase inhibitor, significantly inhibited biofilm formation by P. gingivalis and disrupted established biofilms at concentrations below its MIC against planktonic cells. Oxantel was more effective against P. gingivalis in biofilm than metronidazole, a commonly used antibiotic for periodontitis.

Systematic review on the effect of rinsing with povidone-iodine during nonsurgical periodontal therapy

BACKGROUND AND OBJECTIVE

The existing literature is inconsistent regarding whether there is any additional effect of povidone-iodine (PVP-iodine) as an adjunctive to scaling and root planing, and, if there is an effect, what its size is. Therefore, the aim of this study was to assess the additional effect of PVP-iodine as an adjunct to scaling and root planing compared with water, saline or no rinse in the treatment of chronic periodontitis.

MATERIAL AND METHODS

An electronic literature search of the databases PubMed, EMBASE and the Cochrane Central Library, and a handsearch, were performed (up to November 2008). Two reviewers independently identified and selected screened abstracts for possible inclusion, and assessed randomized, controlled clinical trials comparing the additional benefit of PVP-iodine with water, saline rinsing or no rinsing in the nonsurgical periodontal therapy of patients with chronic periodontitis. A fixed-effects meta-analysis was conducted in the absence of statistically significant heterogeneity.

RESULTS

A small, but statistically significant additional beneficial effect of the adjunctive use of PVP-iodine with enhanced probing pocket depth reductions of 0.28 mm (95% confidence interval: 0.08 to 0.48, p = 0.007) was found. There was no significant heterogeneity between studies (I(2) = 0%). However, most of the studies included in the meta-analysis were of low quality, and the treatment modalities showed various differences such as the use of PVP-iodine at different concentrations and application modalities. Nevertheless, single-rooted teeth, in particular, showed an additional benefit after scaling and root planing with PVP-iodine, particularly when the treatment was repeated during the healing stage.

CONCLUSION

The adjunctive use of PVP-iodine during scaling and root planing may increase the clinical pocket depth reduction, although the clinical significance is small to moderate.

Periodontal therapy reduces plasma levels of interleukin-6, C-reactive protein, and fibrinogen in patients with severe periodontitis and refractory arterial hypertension

BACKGROUND

Recent epidemiologic studies suggest that inflammation is the link between periodontal diseases and cardiovascular complications. This study aimed to evaluate the effects of non-surgical periodontal treatment on plasma levels of inflammatory markers (interleukin [IL]-6, C-reactive protein [CRP], and fibrinogen) in patients with severe periodontitis and refractory arterial hypertension.

METHODS

Twenty-two patients were examined and randomly divided into two groups. The test group was composed of 11 patients (mean age, 48.9 +/- 3.9 years) who received periodontal treatment, whereas the control group had 11 patients (mean age, 49.7 +/- 6.0 years) whose treatment was delayed for 3 months. Demographic and clinical periodontal data were collected, and blood tests were performed to measure the levels of IL-6, CRP, and fibrinogen at baseline and 3 months later.

RESULTS

The clinical results showed that the mean percentages of sites with bleeding on probing, probing depth (PD) 4 to 5 mm, PD > or =6 mm, clinical attachment loss (CAL) 4 to 5 mm, and CAL > or =6 mm were significantly reduced in the test group 3 months after periodontal treatment. There were no significant differences between the data at baseline and 3 months in the control group. Periodontal treatment significantly reduced the blood levels of fibrinogen, CRP, and IL-6 in the test group.

CONCLUSION

Non-surgical periodontal therapy was effective in improving periodontal clinical data and in reducing the plasma levels of IL-6, CRP, and fibrinogen in hypertensive patients with severe periodontitis.

Prevention and therapeutic approaches to gingival inflammation

The most important preventive and therapeutic effort to reduce inflammation is to remove the dental plaque thoroughly. Oral self-care is thus of crucial importance to achieve and maintain oral health. There is a scarcity of scientific evidence on the most effective models for behavioural change aimed to improve oral hygiene. There is a need for randomized-controlled trials, based on behavioural sciences and performed with great methodological rigour, to investigate the usefulness of these proposed behavioural changes. Oral hygiene regimens for patients with natural teeth as well as dental implants should include brushing twice daily, inter-dental cleaning once daily and rinsing with efficient rinses as an adjunct to mechanical infection control. Power toothbrushes are preferable as they are more effective than manual toothbrushes. Inter-dental brushes seem to be most effective and useful for inter-dental cleaning. Scaling and root planing is effective in reducing inflammation and probing depths in patients with periodontitis.

Circulating interleukin-6 and high-sensitivity C-reactive protein decrease after periodontal therapy in otherwise healthy subjects

BACKGROUND

Periodontal disease has been associated with many chronic inflammatory systemic diseases, and a common chronic inflammation pathway has been suggested for these conditions. However, few studies have evaluated whether periodontal disease, in the absence of other known inflammatory conditions and smoking, affects circulating markers of chronic inflammation. This study compared chronic inflammation markers in control individuals and patients with periodontal disease and observed whether non-surgical periodontal therapy affected inflammatory disease markers after 3 months.

METHODS

Plasma and serum of 20 controls and 25 patients with periodontal disease were obtained prior to and 3 months after non-surgical periodontal therapy. All patients were non-smokers, they did not use any medication, and they had no history or detectable signs and symptoms of systemic diseases. Periodontal and systemic parameters included probing depth, bleeding on probing, clinical attachment level, hematologic parameters, as well as the following inflammatory markers: interleukin (IL)-6, high-sensitivity C-reactive protein (hs-CRP), CD40 ligand, monocyte chemoattractant protein (MCP)-1, soluble P-selectin (sP-selectin), soluble vascular adhesion molecule (sVCAM)-1, and soluble intercellular adhesion molecule (sICAM)-1.

RESULTS

There were no differences in the hematologic parameters of the patients in the control and periodontal disease groups. Among the tested inflammatory markers, IL-6 concentrations were higher in the periodontal disease group at baseline compared to the controls (P = 0.006). Therapy was highly effective (P <0.001 for all the analyzed clinical parameters), and a decrease in circulating IL-6 and hs-CRP concentrations was observed 3 months after therapy (P = 0.001 and P = 0.006, respectively). Our results also suggest that the CD40 ligand marker may have been different in the control and periodontal disease groups prior to the therapy (P = 0.009).

CONCLUSIONS

In apparently otherwise healthy patients, periodontal disease is associated with increased circulating concentrations of IL-6 and hs-CRP, which decreased 3 months after non-surgical periodontal therapy. With regard to the CD40 ligand, MCP-1, sP-selectin, sVCAM-1, and sICAM-1, no changes were seen in the periodontal disease group between baseline and 3 months after therapy.

Age-related alterations in innate immune receptor expression and ability of macrophages to respond to pathogen challenge in vitro

The impact of ageing in innate immunity is poorly understood. Studies in the mouse model have described altered innate immune functions in aged macrophages, although these were not generally linked to altered expression of receptors or regulatory molecules. Moreover, the influence of ageing in the expression of these molecules has not been systematically examined. We investigated age-dependent expression differences in selected Toll-like and other pattern-recognition receptors, receptors involved in inflammatory amplification, and in transmembrane and intracellular regulators of inflammatory signaling. Young and aged macrophages were examined under resting conditions or upon activation with Porphyromonas gingivalis, a major pathogen in periodontal disease, the prevalence and severity of which increase in old age. We detected a limited number of age-dependent alterations, involving both reduction and increase of immune activity. Interestingly, surface expression of receptors that amplify inflammation (C5a anaphylatoxin receptor and triggering receptor expressed on myeloid cells [TREM]-1) was elevated in aged macrophages. No significant age-dependent differences were observed regarding the phagocytosis and intracellular killing of P. gingivalis, consistent with lack of significant changes in phagocytic receptor expression and induction of antimicrobial molecules. Therefore, at least at the cellular level, certain aspects of innate immune function may not necessarily decline with age.

Lipopolysaccharide biosynthesis-related genes are required for colony pigmentation of Porphyromonas gingivalis

The periodontopathic bacterium Porphyromonas gingivalis forms pigmented colonies when incubated on blood agar plates as a result of accumulation of mu-oxo haem dimer on the cell surface. Gingipain-adhesin complexes are responsible for production of mu-oxo haem dimer from haemoglobin. Non-pigmented mutants (Tn6-5, Tn7-1, Tn7-3 and Tn10-4) were isolated from P. gingivalis by Tn4351 transposon mutagenesis [Hoover & Yoshimura (1994), FEMS Microbiol Lett 124, 43-48]. In this study, we found that the Tn6-5, Tn7-1 and Tn7-3 mutants carried Tn4351 DNA in a gene homologous to the ugdA gene encoding UDP-glucose 6-dehydrogenase, a gene encoding a putative group 1 family glycosyltransferase and a gene homologous to the rfa gene encoding ADP heptose-LPS heptosyltransferase, respectively. The Tn10-4 mutant carried Tn4351 DNA at the same position as that for Tn7-1. Gingipain activities associated with cells of the Tn7-3 mutant (rfa) were very weak, whereas gingipain activities were detected in the culture supernatants. Immunoblot and mass spectrometry analyses also revealed that gingipains, including their precursor forms, were present in the culture supernatants. A lipopolysaccharide (LPS) fraction of the rfa deletion mutant did not show the ladder pattern that was usually seen for the LPS of the wild-type P. gingivalis. A recombinant chimera gingipain was able to bind to an LPS fraction of the wild-type P. gingivalis in a dose-dependent manner. These results suggest that the rfa gene product is associated with biosynthesis of LPS and/or cell-surface polysaccharides that can function as an anchorage for gingipain-adhesin complexes.