Blocking periodontal disease progression with anti-inflammatory agents

Roles of specialized pro-resolving mediators and omega-3 polyunsaturated fatty acids in periodontal inflammation and impact on oral microbiota

Periodontitis is a chronic inflammatory disease induced by dysbiotic dental biofilms. Management of periodontitis is primarily anti-bacterial via mechanical removal of bacterial biofilm. The successful resolution requires wound healing and tissue regeneration, which are not always achieved with these traditional methods. The discovery of specialized pro-resolving mediators (SPMs), a class of lipid mediators that induce the resolution of inflammation and promote local tissue homeostasis, creates another option for the treatment of periodontitis and other diseases of chronic inflammation. In this mini-review, we discuss the host-modulatory effects of SPMs on periodontal tissues and changes in the taxonomic composition of the gut and oral microbiome in the presence of SPMs and SPM precursor lipids. Further research into the relationship between host SPM production and microbiome-SPM modification has the potential to unveil new diagnostic markers of inflammation and wound healing. Expanding this field may drive the discovery of microbial-derived bioactive therapeutics to modulate immune responses.

Assessment of Periodontal status in Patients with Psoriatic Arthritis: A retrospective, case-control study

BACKGROUND

Psoriatic arthritis (PsA) and periodontitis both represent chronic inflammatory disorders that share similar pathophysiological processes. However, very few studies have been done to address the link between the two diseases which remains poorly understood. The present study aimed to assess and compare the periodontal status in patients suffering from PsA and systemically healthy subjects to identify whether a possible association exists between PsA and periodontitis.

MATERIAL AND METHODS

Periodontal parameters - PI, BOP, mGI, PPD and CAL were recorded in 110 patients with PsA and 110 age- and gender-matched systemically healthy patients. Mean values of the periodontal parameters were calculated for both groups and subjected to statistical analysis. Logistic regression analysis was performed to correlate the demographic data with periodontitis.

RESULTS

The frequency of periodontitis and mean values of BOP, mGI, PPD and CAL were found to be significantly higher in patients with PsA than in systemically healthy controls. The number of patients with stage III periodontitis was found to be significantly higher in the PsA group.

CONCLUSIONS

A possible link exists between periodontitis and psoriatic arthritis, as exhibited by the results of the present study. Dental and medical health professionals should be aware of this relationship depending on which, they should carry out adequate treatment strategies involving periodic periodontal evaluation and care. Key words:Periodontitis, psoriatic arthritis, chronic inflammation, probing pocket depth, clinical attachment loss.

Modular design of a hybrid hydrogel for protease-triggered enhancement of drug delivery to regulate TNF-α production by pro-inflammatory macrophages

Systemic drug administration has conventionally been prescribed to alleviate persistent local inflammation which is prevalent in chronic diseases. However, this approach is associated with drug-induced toxicity, particularly when the dosage exceeds that necessitated by pathological conditions of diseased tissues. Herein, we developed a modular hybrid hydrogel which could be triggered to release an anti-inflammatory drug upon exposure to elevated protease activity associated with inflammatory diseases. Modular design of the hybrid hydrogel enabled independent optimization of its protease-cleavable and drug-loaded subdomains to facilitate hydrogel formation, cleavability by matrix-metalloprotease-9 (MMP-9), and tuning drug release rate. In vitro study demonstrated the protease-triggered enhancement of drug release from the hybrid hydrogel system for effective inhibition of TNF-α production by pro-inflammatory macrophages and suggested its potential to mitigate drug-induced cytotoxicity. Using non-invasive imaging to monitor the activity of reactive oxygen species in biomaterial-induced host response, we confirmed that the hybrid hydrogel and its constituent materials did not induce adverse immune response after 5 days following their subcutaneous injection in immuno-competent mice. We subsequently incorporated this hybrid hydrogel onto a commercial wound dressing which could release the drug upon exposure to MMP-9. Together, our findings suggested that this hybrid hydrogel might be a versatile platform for on-demand drug delivery via either injectable or topical application to modulate inflammation in chronic diseases.

Omega-3 Fatty Acids Effects on Inflammatory Biomarkers and Lipid Profiles among Diabetic and Cardiovascular Disease Patients: A Systematic Review and Meta-Analysis

The purpose of this systematic review and meta-analysis was to investigate omega-3 fatty acids’ influence on 12 inflammatory biomarkers—LDL, HDL, total cholesterol, TG, HbA1c, Apo AI, Apo AII, Apo B, CRP, TNF-α, glucose, and fasting blood glucose among diabetic and cardiovascular disease (CVD) patients. We searched articles in six database engines, and 16 of the 696 articles reviewed met the inclusion criteria. Among these, lipid and inflammatory biomarkers investigated commonly included total cholesterol (11 studies), LDL, and TG (10 studies each). Overall, omega-3 was associated with a significant reduction in Apo AII among diabetic patients, as compared to different controls (−8.0 mg/dL 95% CI: −12.71, −3.29, p = 0.0009), triglycerides (−44.88 mg/dL 95% CI: −82.6, −7.16, p < 0.0001), HDL (−2.27 mg/dL 95% CI: −3.72, −0.83, p = 0.002), and increased fasting blood glucose (16.14 mg/dL 95% CI: 6.25, 26.04, p = 0.001). Omega-3 also was associated with increased LDL among CVD patients (2.10 mg/dL 95% CI: 1.00, 3.20, p = 0.0002). We conclude that omega-3 fatty acids may be associated with lower inflammatory biomarkers among diabetic and cardiovascular patients. Clinicians should be aware of these potential benefits; however, it is essential to recommend that patients consult with clinicians before any omega-3 intake.

Odontal-Periodontal Changes in Patients with Type 1 Diabetes

ABSTRACT: Diabetes mellitus is a complex disease characterized by insufficient insulin secretion and / or an inefficiency of target tissues to its metabolic action. Periodontal disease was recognized as the sixth leading complication of a diabetes. Gingival sulcus bleeding is considered as an important clinical parameter in the diagnosis of periodontal disease. This research is based on comparison of the clinical and paraclinical data between groups of patients with type 1 diabetes and periodontal disease on the one hand and groups of patients with periodontal disease without diabetic disease on the other hand. We can conclude that there is sufficient data to confirm the existence of a bidirectional relationship between metabolic changes in type 1 diabetes and periodontal (odontal-periodontal) disorder of patients, especially in adolescents and young adults. Both diseases can influence each other more or less, so for diabetics there is a predilection to develop periodontal disease as diabetes is a risk factor for severe parodontopathies.

Resolvin E1 Reverses Experimental Periodontitis and Dysbiosis

Periodontitis is a biofilm-induced inflammatory disease characterized by dysbiosis of the commensal periodontal microbiota. It is unclear how natural regulation of inflammation affects the periodontal biofilm. Promoters of active resolution of inflammation, including resolvin E1 (RvE1), effectively treat inflammatory periodontitis in animal models. The goals of this study were 1) to compare periodontal tissue gene expression in different clinical conditions, 2) to determine the impact of local inflammation on the composition of subgingival bacteria, and 3) to understand how inflammation impacts these changes. Two clinically relevant experiments were performed in rats: prevention and treatment of ligature-induced periodontitis with RvE1 topical treatment. The gingival transcriptome was evaluated by RNA sequencing of mRNA. The composition of the subgingival microbiota was characterized by 16S rDNA sequencing. Periodontitis was assessed by bone morphometric measurements and histomorphometry of block sections. H&E and tartrate-resistant acid phosphatase staining were used to characterize and quantify inflammatory changes. RvE1 treatment prevented bone loss in ligature-induced periodontitis. Osteoclast density and inflammatory cell infiltration in the RvE1 groups were lower than those in the placebo group. RvE1 treatment reduced expression of inflammation-related genes, returning the expression profile to one more similar to health. Treatment of established periodontitis with RvE1 reversed bone loss, reversed inflammatory gene expression, and reduced osteoclast density. Assessment of the rat subgingival microbiota after RvE1 treatment revealed marked changes in both prevention and treatment experiments. The data suggest that modulation of local inflammation has a major role in shaping the composition of the subgingival microbiota.

Prevalence of Periodontitis in Patients with Established Rheumatoid Arthritis: A Swedish Population Based Case-Control Study

INTRODUCTION

The possible hypothesis of a link between periodontitis and rheumatoid arthritis (RA), specifically anti-citrullinated protein antibody (ACPA) positive RA, prompted us to investigate the prevalence of periodontitis in the Swedish Epidemiological Investigation of RA (EIRA), a well-characterised population-based RA case-control cohort.

METHODS

Periodontal status of 2,740 RA cases and 3,942 matched controls was retrieved through linking EIRA with the National Dental Health Registry (DHR), where dental diagnostic- and treatment codes on the adult Swedish population have been registered. Dental records from 100 cases and controls were reviewed to validate the periodontal diagnostic codes in DHR.

RESULTS

The reviewed dental records confirmed 90% of the periodontitis diagnoses in DHR among RA cases, and 88% among controls. We found the positive predictive value of periodontitis diagnoses in the DHR to be 89% (95% CI 78 to 95%) with a sensitivity of 77% (95% CI: 65 to 86%). In total, 86% of EIRA participants were identified in DHR. The risk for periodontitis increased by age and current smoking status in both cases as well as controls. No significant differences in prevalence of periodontal disease in terms of gingivitis, periodontitis, peri-implantitis or increased risk for periodontitis or peri-implantitis were observed between RA cases and controls. In addition, there was no difference on the basis of seropositivity, ACPA or rheumatoid factor (RF), among patients with RA.

CONCLUSIONS

Our data verify that smoking and ageing are risk factors for periodontitis, both in RA and controls. We found no evidence of an increased prevalence of periodontitis in patients with established RA compared to healthy controls, and no differences based on ACPA or RF status among RA subjects.

Expression of anti-Porphyromonas gingivalis peptidylarginine deiminase immunoglobulin G and peptidylarginine deiminase-4 in patients with rheumatoid arthritis and periodontitis

BACKGROUND AND OBJECTIVE

Autoimmunity against citrullinated proteins through peptidylarginine deiminase (PAD) may be involved in the pathophysiology of rheumatoid arthritis (RA). The present study evaluated the serum levels of antibodies to citrullinated proteins and to Porphyromonas gingivalis PAD (PPAD), and the endogenous expression of PAD-4, in individuals with and without RA, as well as before and after periodontal treatment.

MATERIAL AND METHODS

The study participants consisted of 52 patients with RA (RA group) and 26 age-, gender- and smoking status-matched healthy controls (non-RA group). Of the 52 patients, 26 were randomly assigned to receive oral hygiene instruction and supragingival scaling (RA subgroup). After periodontal and rheumatologic assessments, the serum levels of anti-cyclic citrullinated peptide (CCP) immunoglobulin G (IgG), anti-PPAD IgG and PAD-4 were determined using ELISA.

RESULTS

The serum levels of anti-CCP IgG and anti-PPAD IgG were significantly higher in the RA group than in the non-RA group (p < 0.001 and p = 0.03). A significant, positive correlation was observed between the serum levels of anti-PPAD IgG and anti-CCP IgG (p = 0.04), but not between the serum levels of PAD-4 and anti-CCP IgG. Multiple logistic regression analyses revealed a significant association between anti-PPAD IgG responses and RA after adjustment for age, gender and smoking (p = 0.004). Supragingival scaling significantly improved the periodontal condition and disease activity of RA (p < 0.05), but failed to decrease the serum levels of anti-CCP IgG, anti-PPAD IgG and PAD-4 after 2 mo of treatment.

CONCLUSION

These results might suggest an association between anti-PPAD IgG and anti-CCP IgG responses, implicating a role for PPAD in protein citrullination in patients with RA and periodontitis.

Natural resolution of inflammation

Inflammation is a protective response essential for maintaining human health and for fighting disease. As an active innate immune reaction to challenge, inflammation gives rise to clinical cardinal signs: rubor, calor, dolor, tumor and functio laesa. Termination of acute inflammation was previously recognized as a passive process; a natural decay of pro-inflammatory signals. We now understand that the natural resolution of inflammation involves well-integrated, active, biochemical programs that return tissues to homeostasis. This review focuses on recent advances in the understanding of the role of endogenous lipid mediators that modulate cellular fate and inflammation. Biosynthesis of eicosanoids and other lipids in exudates coincides with changes in the types of inflammatory cells. Resolution of inflammation is initiated by an active class switch in lipid mediators, such as classic prostaglandins and leukotrienes, to the production of proresolution mediators. Endogenous pro-resolving lipid mediators, including arachidonic acid-derived lipoxins, aspirin-triggered lipoxins, ω3-eicosapentaenoic acid-derived resolvins of the E-series, docosahexaenoic acid-derived resolvins of the D-series, protectins and maresins, are biosynthesized during the resolution phase of acute inflammation. Depending on the type of injury and the type of tissue, the initial cells that respond are polymorphonuclear leukocytes, monocytes/macrophages, epithelial cells or endothelial cells. The selective interaction of specific lipid mediators with G protein-coupled receptors expressed on innate immune cells (e.g. G protein-coupled receptor 32, lipoxin A4 receptor/formyl peptide receptor2, chemokine-like receptor 1, leukotriene B4 receptor type 1 and cabannoid receptor 2) induces cessation of leukocyte infiltration; vascular permeability/edema returns to normal with polymorphonuclear neutrophil death (mostly via apoptosis), the nonphlogistic infiltration of monocyte/macrophages and the removal (by macrophages) of apoptotic polymorphonuclear neutrophils, foreign agents (bacteria) and necrotic debris from the site. While an acute inflammatory response that is resolved in a timely manner prevents tissue injury, inadequate resolution and failure to return tissue to homeostasis results in neutrophil-mediated destruction and chronic inflammation. A better understanding of the complex mechanisms of lipid agonist mediators, cell targets and actions allows us to exploit and develop novel therapeutic strategies to treat human inflammatory diseases, including periodontal diseases.

Formulation development of novel in situ nanoemulgel (NEG) of ketoprofen for the treatment of periodontitis

The aim of the present study was to formulate and evaluate in situ gelling syringeable nanoemulgels (NEGs) of ketoprofen for periodontal delivery. Application of 3-factor 3-level design was employed using the Box-Behnken experimental design for the optimization of nanoemulsion using three independent variables such as percent concentration (v/v) of oil (X1), S mix (mixture of surfactant and cosurfactant) (X2) and water (X3); while the particle size (nm) (Y1), polydispersity index (Y2) and zeta potential (mV) (Y3) were used as dependent variables. The NEG was evaluated based on their drug content, pH measurement, mucoadhesion on the goat buccal mucosa, syringeability and inverted sol-gel transition temperature. The drug release data were analyzed for curve fitting based on the Korsmeyer-Peppas law, and the n-values of optimized A5 and A8 formulations were found 0.3721 and 0.3932, respectively, confirmed that both the formulations followed pseudo Fickian diffusion (n < 0.43). The formulation A8 with the optimal drug release was identified as the best NEG formulation. Results of rheological, mucoadhesion and syringeability studies showed the suitability of desired sol-gel property for periodontal drug delivery. The Herschel-Bulkley model was the best fit model to explain the flow behavior of optimized formulation. Using the HET-CAM method, significantly lower in vitro toxicity was indicated the suitability of developed NEG for intra-pocket delivery.

Lessons learned and unlearned in periodontal microbiology

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

Periodontal disease in patients with psoriatic arthritis

Rheumatological diseases and periodontal disease are both characterized by dysregulation of the host inflammatory response. The aim of this study was to determine the possible relationship between periodontitis and psoriatic arthritis (PsA). Fifty-one adults with PsA (27 men and 24 women; mean age 41.73 ± 11.27 years) and 50 age- and gender-balanced systemically healthy control subjects participated in the study. Participants' periodontal status as determined by probing pocket depth, clinical attachment loss (CAL), plaque index, and gingival index was evaluated. The CAL levels of the PsA group were significantly higher than those of the control group (p < 0.05) There were no statistically significant differences in the frequency of periodontitis, probing pocket depth, plaque index, or gingival index between the two groups. The results of the present study show that periodontitis severity as determined by CAL was higher in the PsA group; therefore, periodontal evaluation must be considered when PsA is diagnosed.

Periodontal treatment decreases levels of antibodies to Porphyromonas gingivalis and citrulline in patients with rheumatoid arthritis and periodontitis

BACKGROUND

Porphyromonas gingivalis has been implicated as an etiologic agent of rheumatoid arthritis (RA) because of the expression of peptidylarginine deiminase. The present study evaluates whether periodontal treatment may affect serum antibodies to P. gingivalis and citrulline levels in relation to disease activity of RA.

METHODS

Fifty-five patients with RA were randomly assigned to receive oral hygiene instruction and supragingival scaling (treatment group, n = 26) or no periodontal treatment (control group, n = 29). Periodontal and rheumatologic parameters and serum levels of cytokine and inflammatory markers citrulline and immunoglobulin (Ig)G to P. gingivalis were examined at baseline and 8 weeks later.

RESULTS

Both groups did not differ statistically in any parameters except percentage of sites with probing depth and clinical attachment level ≥ 4 mm at baseline. The treatment group exhibited a significantly greater decrease in disease activity score including 28 joints using C-reactive protein (DAS28-CRP) (P = 0.02), serum levels of IgG to P. gingivalis hemin binding protein (HBP)35 (P = 0.04), and citrulline (P = 0.02) than the control group. Serum levels of IgG to P. gingivalis HBP35 were significantly correlated positively with those of anti-cyclic citrullinated peptide antibodies (P = 0.0002). The same correlation was obtained between serum levels of IgG to P. gingivalis-sonicated extracts and those of rheumatoid factor (P = 0.02).

CONCLUSIONS

These results suggest that supragingival scaling decreases DAS28-CRP and serum levels of IgG to P. gingivalis HBP35 and citrulline in patients with RA. These observations may reflect a role of P. gingivalis in the protein citrullination, which is related to the pathogenesis of RA.

Evaluative comparison of systemic aspirin therapy effects on gingival bleeding in post non-surgical periodontal therapy individuals

BACKGROUND

Gingival bleeding is considered as an important clinical sign for diagnosis of periodontal disease pathogenesis. Immune inflammatory reactions caused by local factors are considered as essential reasons for gingival bleeding, as also for the systemic bleeding disorders. In disease-free conditions of gingiva, the bleeding disorders are considered to be the main contender for bleeding. Other than these variables, many systemic drugs including systemic aspirin could also cause gingival bleeding. The main aim of the study was to evaluate the effect of buffered aspirin therapy on gingival bleeding.

MATERIALS AND METHODS

Totally, 36 systemically healthy individuals were included in the 15-day randomized, double-blinded, placebo-controlled clinical trial. The 15 days were divided as: control period for the first 7 days and study period for the following 7 days. On the 1(st) day, all individuals were given oral prophylaxis after recording gingival parameters such as Plaque Index, probing depth, and Bleeding Index, and then blood samples were collected for hematological investigations. Then, all individuals were administered placebo capsules for 1 week as once daily dose. On the 8(th) day, all procedures were repeated and the individuals were prescribed with 325 coated aspirin capsules for 1 week. On the 15(th) day, all parameters were repeated and the results were statistically analyzed.

RESULTS

In the study period, the parameters such as Bleeding Index, bleeding time, and prothrombin time were increased significantly, compared to the control period.

CONCLUSION

The variables such as systemic drug therapy should be considered for the examination of gingiva while the diagnosis is considered mainly based on gingival bleeding.

Serum cytokine levels and periodontal parameters in ankylosing spondylitis

BACKGROUND AND OBJECTIVE

Multiple studies support the role of periodontal disease in contributing to the chronic systemic inflammatory burden in a variety of diseases, including ankylosing spondylitis (AS), in the progression which the inflammatory process plays an important role. We assume that patients with AS are more likely to have periodontal disease than healthy individuals. The aim of this study was to determine the possible relationship between inflammatory periodontal diseases and AS by evaluating clinical periodontal parameters and serum cytokine levels.

MATERIAL AND METHODS

Forty-eight adults with AS (35 women and 13 men; age range 18-56 years; mean age 34.27 years) and 48 age- and sex-matched systemically healthy control subjects participated in the study. The clinical periodontal parameters, venous blood and Bath Ankylosing Spondylitis Disease Activity Score were obtained, and serum C-reactive protein, tumour necrosis factor-α and interleukin-6 (IL-6) levels were evaluated.

RESULTS

There was statistically no significant difference in the frequency of periodontitis between AS patients and the control group. Furthermore, there was no significant difference in probing depth, clinical attachment level and plaque index, and the only significant clinical difference between groups was in levels of bleeding on probing (p < 0.001). Serum concentrations of IL-6, tumour necrosis factor-α and C-reactive protein in the AS group were significantly higher than those in the control group (p < 0.001). In the AS group, there was a correlation between serum IL-6 levels and clinical attachment level (p < 0.001).

CONCLUSION

The results of present study suggest that bleeding on probing was the only different periodontal parameter between the AS and the control group, and the periodontal status of patients with AS may be affected by IL-6 levels.

Antibody responses to periodontopathic bacteria in relation to rheumatoid arthritis in Japanese adults

BACKGROUND

Periodontopathic bacteria have been implicated as contributory to the etiology of rheumatoid arthritis (RA). Anticyclic citrullinated peptide (CCP) antibodies and rheumatoid factor (RF) were shown to be associated with RA. This study examines whether serum levels of antibodies to periodontopathic bacteria may affect clinical and laboratory profiles of RA.

METHODS

The study participants consisted of 80 patients with RA, and 38 age-, sex-, smoking status-, and periodontal condition-balanced healthy controls. After periodontal and rheumatologic examination, serum levels of immunoglobulin G (IgG) antibodies to Porphyromonas gingivalis (Pg), Prevotella intermedia, Aggregatibacter actinomycetemcomitans (Aa) (previously Actinobacillus actinomycetemcomitans), and Eikenella corrodens (Ec) and those of anti-CCP antibodies and RF were determined by an enzyme-linked immunosorbent assay.

RESULTS

Patients with RA showed significantly higher levels of anti-Pg and anti-CCP antibodies than controls (P = 0.04 and P <0.0001). In contrast, IgG responses to Aa and Ec in patients with RA were significantly lower than those in controls (P <0.0001 and P = 0.0001). Multiple logistic regression analysis revealed a significant association of anti-Pg and anti-Aa IgG responses with RA, after adjustment for age, sex, and smoking (P = 0.005 and P = 0.02). Anti-Pg titer displayed a significant correlation with RF levels, probing depth, and clinical attachment level (P = 0.03, P = 0.03, and P = 0.02).

CONCLUSION

These results suggest that serum levels of anti-Pg IgG antibodies were associated with RA, and might affect serum levels of RF and periodontal condition in patients with RA.

Serum cytokine and periodontal profiles in relation to disease activity of rheumatoid arthritis in Japanese adults

BACKGROUND

Rheumatoid arthritis (RA) and periodontitis are common chronic inflammatory conditions and share many pathologic features. A similar profile of cytokines is involved in the pathogenesis of the two diseases. The relationship between the disease activity of RA and the periodontal condition remains unclear. This study examines whether the disease activity of RA affects serum cytokine and periodontal profiles.

METHODS

The study subjects consisted of 84 Japanese adults with RA and 22 race-matched control individuals. After periodontal and rheumatologic examination, the disease activity of RA was determined with the Disease Activity Score including 28 joints using C-reactive protein (DAS28-CRP). Serum levels of cytokines including interleukin (IL)-1beta, IL-6, IL-12, IL-12 p40, IL-18, and tumor necrosis factor-alpha (TNF-alpha) were determined by an enzyme-linked immunosorbent assay. High-sensitive CRP was also measured with a latex particle-enhanced nephelometric method.

RESULTS

Of 84 patients with RA, 28 and 56 patients exhibited low and moderate to high disease activity, respectively. Serum levels of IL-6, TNF-alpha, and CRP were significantly different between the two groups (P <0.05). Additionally, a significant correlation was observed between DAS28-CRP and percentage of sites with bleeding on probing (BOP) (P = 0.008) and between serum TNF-alpha levels and percentage of sites with BOP (P = 0.01) in 56 patients with RA with moderate to high activity.

CONCLUSION

These results suggest that the disease activity of RA correlated with serum levels of IL-6, TNF-alpha, and CRP, and it might influence BOP in the patients with moderate to high disease activity.

Periodontitis in systemic rheumatic diseases

Periodontitis is a chronic inflammatory disease that is characterized by loss of the periodontal ligament and alveolar bone, and is a major cause of tooth loss. Results from clinical and epidemiologic studies have suggested that periodontitis and tooth loss are more prevalent in individuals with rheumatoid arthritis (RA). However, the strength and temporality of the association are uncertain. Several biologically plausible causal and noncausal mechanisms might account for this association between periodontitis and RA. There is evidence to suggest that periodontitis could indeed be a causal factor in the initiation and maintenance of the autoimmune inflammatory response that occurs in RA. If proven, chronic periodontitis might represent an important modifiable risk factor for RA. In addition, patients with RA might show an increased risk of developing periodontitis and tooth loss through various mechanisms. Moreover, exposure to common genetic, environmental or behavioral factors might contribute to a noncausal association between both conditions.

Gingival crevicular fluid prostaglandin E(2) and thiobarbituric acid reactive substance levels in smokers and non-smokers with chronic periodontitis following phase I periodontal therapy and adjunctive use of flurbiprofen

BACKGROUND

It has been established that smoking is an important risk factor for the initiation and progression of chronic periodontitis (CP). This study investigates the effects of phase I periodontal therapy and adjunctive flurbiprofen administration on prostaglandin E(2) (PGE(2)) and thiobarbituric acid reactive substance (TBARS) levels in gingival crevicular fluid (GCF) samples from smoker and non-smoker patients with CP.

METHODS

Twenty-one non-smoker and 21 smoker patients with CP were divided into four groups according to treatment modalities. Group 1 (non-smokers with CP) and group 3 (smokers with CP) patients received daily 100-mg flurbiprofen tablets in a 2 x 1 regimen for 10 days together with scaling and root planing (SRP). Patients in group 2 (non-smokers with CP) and group 4 (smokers with CP) received placebo tablets in a 2 x 1 regimen for 10 days together with SRP. Plaque index (PI), gingival index (GI), probing depth (PD), and clinical attachment level (CAL) measurements were recorded and GCF samples were collected at baseline and on day 10 of drug intake from each sampling area by a single examiner who was unaware of the treatment modality. Assays for GCF PGE(2) and TBARS were carried out by an enzyme-linked immunosorbent assay and fluorometric method, respectively.

RESULTS

All groups showed statistically significant reductions in PI and GI scores following the phase I periodontal treatment on day 10 (P <0.05), but no statistical differences were observed in PD and CAL scores after the therapy. In groups 1 and 2, the reduction of GCF PGE(2) and TBARS levels were not significant after the therapy compared to baseline levels. In group 3, GCF PGE(2) and TBARS levels exhibited a statistically significant decrease (P <0.05) after the therapy. Group 4 showed significant reductions (P <0.05) in GCF PGE(2) levels after the therapy. No statistically significant reductions were observed in group 4 with regard to GCF TBARS levels. When groups 1 and 3 were compared according to GCF TBARS levels after the therapy, a more statistically significant reduction was observed in group 3 (P = 0.001).

CONCLUSION

These results suggest that additional flurbiprofen administration may have more inhibitory effects on GCF levels of PGE(2) and TBARS in the groups of smokers compared to non-smokers with CP.

Effect of meloxicam on gingival crevicular fluid IL-1beta and IL1 receptor antagonist levels in subjects with chronic periodontitis, and its effects on clinical parameters

The aim of the present study was to determine the effects of meloxicam after initial periodontal treatment on interleukin-1beta (IL-1beta) and IL-1 receptor antagonist (IL-1ra) in gingival crevicular fluid (GCF) and clinical parameters in the chronic periodontitis patients. Data were obtained from 30 patients with chronic periodontitis. Fifteen chronic periodontitis patients received 7.5 mg meloxicam, and 15 patients received placebo tablets in a 1x1 regimen for 1 month. All subjects were nonsmokers and had not received any periodontal therapy. The plaque index (PI), gingival index (GI), probing depth (PD), and clinical attachment level (CAL) were recorded. The GCF was collected using a paper strip: eluted and enzyme-linked immunoabsorbent assays (ELISAs) were performed to determine the cytokine levels. The clinical data and GCF samples were obtained after periodontal therapy and 1 month after periodontal therapy. The PI, GI, PD, and GCF IL-1ra decreased significantly (p<0.05) in meloxicam group at first month when comparing the initial levels. While decrease of the PI was statistically significant in control group (p<0.05), statistically significant changes were not determined in the other clinical parameters and GCF cytokine levels (p>0.05). There were no significant differences between two groups in any of the investigated parameters. Our observations did not reveal any influence of meloxicam on levels of IL-1beta and IL-1ra in chronic periodontitis. Additional clinical studies are advisable to determine whether COX-2 selective drugs alter periodontal disease outcome with greater safety.

Adjunctive subantimicrobial dose doxycycline: effect on clinical parameters and gingival crevicular fluid transforming growth factor-beta levels in severe, generalized chronic periodontitis

BACKGROUND

At present there is limited data concerning the efficacy of non-surgical periodontal therapy supplemented with subantimicrobial dose doxycycline (SDD) in the treatment of severe, generalized periodontitis. The purpose of the present study was to evaluate the effect of adjunctive SDD therapy on clinical periodontal parameters and gingival crevicular fluid (GCF) transforming growth factor-beta1 (TGF-beta1) levels in patients with severe, generalized chronic periodontitis over a 6-month period.

METHODS

Thirty-five patients with severe, generalized periodontitis and 11 periodontally healthy subjects were included in the present study. Patients received full-mouth supragingival debridment at baseline and randomized to take either SDD b.i.d. or placebo b.i.d. for 3 months. Patients received root planing and oral hygiene instruction once a week for four consecutive weeks. Clinical measurements including probing depth (PD), clinical attachment level, papilla bleeding index and plaque index and GCF sampling were performed at baseline, 3 and 6 months. The GCF TGF-beta1 levels were analysed by enzyme-linked immunosorbent assay.

RESULTS

Thirteen patients in both study groups completed the 6-month trial. Following scaling and root planing (SRP) plus SDD and SRP plus placebo therapy significant improvements in clinical periodontal parameters of both groups were observed (p<0.025). In the SDD group a significantly higher percentage (%73.4) of deep pockets resolved (PD reduction > or =3 mm from baseline) when compared with placebo group (%49.7) at 6 months (p<0.05). At baseline there were no significant differences in GCF TGF-beta1 levels between three groups. Both total amount and concentration of GCF TGF-beta1 in SDD and placebo groups increased when compared with baseline at 3 months. However, only GCF TGF-beta1 levels of SDD group was significantly higher than baseline (p<0.025) and placebo group (p<0.017) at 3 months. At 6 months GCF TGF-beta1 levels of both groups were similar to baseline levels (p<0.025).

CONCLUSIONS

These data indicate that combination of SDD with non-surgical therapy improves clinical parameters of periodontal disease and increases GCF TGF-beta1 levels together with a decrease in prevalence of residual pockets in patients with severe, generalized chronic periodontitis. Increased GCF TGF-beta1 levels following SDD therapy might suggest a novell pleiotrophic mechanism for tetracyclines to inhibit connective tissue breakdown.

Effect of subantimicrobial dose doxycycline as an effective adjunct to scaling and root planing

BACKGROUND

This study evaluated the efficacy and safety of a subantimicrobial dose of doxycycline (SDD) in conjunction with scaling and root planing (SRP).

METHODS

The study was a 9-month, double masked, randomized, placebo-controlled, parallel-group trial. A total of 41 patients with moderate chronic periodontitis who received SRP were randomly allocated to receive either a doxycycline hyclate or a placebo 2 weeks after SRP. Clinical attachment level (CAL), the probing depth (PD), gingival crevicular fluid (GCF) levels, and matrix metalloproteinase (MMP)-8 and -13 levels were measured throughout the study. The effect of SDD in conjunction with SRP on the dynamics of the periodontal microflora was also assessed using dark-field microscopic and culture analysis. Information on adverse events was collected throughout the study.

RESULTS

During the treatment period, per-patient reductions in PD and CAL were demonstrated for both treatment groups, with a significantly greater reduction for the SDD group. The mean value of per-patient change in the GCF was much greater for the SDD group. Microbial analysis showed there were a general tendency for cocci, non-motile rods, and aerobes to increase with increasing treatment duration and a general decreasing tendency for spirochetes, motile rods, and anaerobes and black pigmented bacteria in both treatment groups, but no significant difference between the groups. The MMP-8 and -13 levels of the SDD group gradually reduced with time, and the mean perpatient average was significantly higher than in the placebo group. The adverse events in the SDD group were similar to those in the placebo group.

CONCLUSION

This study suggests that a submicrobial dose of doxycycline as an adjunct therapy with SRP might be safe and effective in the long-term management of chronic periodontitis.

Pilot study of dietary fatty acid supplementation in the treatment of adult periodontitis

The anti-inflammatory effects of both n-3 and n-6 polyunsaturated fatty acids (PUFA) have been demonstrated in vitro and in many disease states, in particular in the treatment of rheumatoid arthritis. The benefit of n-3 PUFA supplementation has been documented in animal models of periodontal inflammation and a trend towards reduced inflammation has been seen in human experimental gingivitis. The purpose of this study was to examine the potential anti-inflammatory effects of PUFA supplementation, by administration of fish oil as a source of the n-3 PUFA, eicosapentaenoic acid, and borage oil as a source of the n-6 PUFA, gamma-linolenic acid (GLA), to adults with periodontitis. Thirty adult human subjects with periodontitis were administered either fish oil 3000 mg daily; borage oil 3000 mg daily; fish oil 1500 and borage oil 1500 mg daily, or placebo. The modified gingival index, the plaque index (PI), periodontal probing depths and beta-glucuronidase levels in gingival crevicular fluid were measured at baseline and after 12 weeks of treatment. Improvement in gingival inflammation was observed in subjects treated with borage oil (P<0.016), with a trend apparent in subjects treated with fish oil or a combination of PUFA. There was no statistically significant improvement in PI, although a trend was apparent in those receiving borage oil. Improvement in probing depth was seen in those subjects treated with either fish oil alone or borage oil alone, but statistical significance was only seen for the comparison of borage oil and placebo (P<0.044). No change was seen in gingival crevicular fluid (GCF) beta-glucuronidase levels. The use of borage oil supplementation, a source of the n-6 PUFA, GLA, can have beneficial effects on periodontal inflammation. n-6 PUFA supplementation seemed to offer more impressive results than either n-3 PUFA supplementation or the combination of lower doses of the two supplements. Additional studies will be necessary to more fully assess the potential of these agents to favorably affect periodontal inflammation.

Effects of selective cyclooxygenase-2 inhibition on gingival tissue levels of prostaglandin E2 and prostaglandin F2alpha and clinical parameters of chronic periodontitis

BACKGROUND

The purpose of the present study was to evaluate the effect of a relatively selective cyclooxygenase (COX)-2 inhibitor (nimesulide) and non-selective COX-1/COX-2 inhibitor (naproxen) used as an adjunct to non-surgical (scaling and root planing [SRP]) periodontal therapy in chronic periodontitis patients on the gingival tissue (GT) levels of prostaglandin (PG)E2 and PGF2alpha.

METHODS

Thirty patients with chronic periodontitis were divided into 3 groups of 10 each. One group received 100 mg of nimesulide; one received 275 mg of naproxen sodium; and the third group received placebo tablets in a 2 x 1 regimen for 10 days as an adjunct to SRP. GT samples were obtained before drug intake and on day 10. Plaque index (PI) and papillary bleeding index (PBI) scores were recorded at baseline, day 10, and at 3 months; probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 3 months. The levels of PGE2 were detected using an enzyme immunoassay (EIA), and the levels of PGF2alpha were analyzed by radioimmunoassay (RIA). Differences among and within the groups were assessed using non-parametric statistical analysis. Ten periodontally healthy individuals served as controls.

RESULTS

All 3 groups showed statistically significant reductions in PBI and PI on day 10 and at 3 months (P < 0.02), and in PD and CAL at 3 months (P < 0.02, P < 0.05, respectively). In the naproxen group, GT PGE2 levels exhibited a significant decrease (P < 0.05). However, the decrease of GT PGE2 levels in the nimesulide group was insignificant (P > 0.05), while a significant increase was observed in the placebo group (P < 0.05) on day 10. Both the nimesulide and naproxen groups showed a significant decrease (P<0.05) in PGF2alpha level, while the placebo group showed a significant increase (P<0.05).

CONCLUSIONS

Nimesulides, relatively selective COX-2 inhibitors, may have additional inhibitory effects on GT PGF2alpha levels in the first week following non-surgical periodontal treatment. However, nimesulide has an insignificant effect on reducing PGE2 levels in gingival tissue. The determination of GT levels of COX-1 and COX-2 enzymes as well as PGE2 and PGF2alpha in long-term studies may provide further support for the adjunctive use of selective COX-2 inhibitors in treatment of chronic periodontitis.

Effects of dental resin components on vascular reactivity

The frequent use of resins in dentistry has raised the question of their compatibility with oral tissues. The present study was undertaken to determine the effects of the resin components methyl methacrylate (MMA), hydroxyethyl methacrylate (HEMA), and triethylene glycol dimethacrylate (TEGDMA) on the reactivity of blood vessels using the isolated rat aorta as a tissue model. MMA, HEMA, and TEGDMA caused endothelium-dependent and -independent relaxation of rat aortic rings in a concentration-related manner. The endothelium-dependent responses of the tissues to all the resins were significantly attenuated by N-nitro-L-arginine methyl ester (L-NAME), indicating the involvement of nitric oxide. The vasorelaxant effects of both MMA and TEGDMA on the intact and denuded aortae were markedly inhibited by indomethacin, providing evidence for the role of prostanoids in these responses. Glybenclamide selectively attenuated TEGDMA-induced relaxation of the tissues with and without endothelium to a similar extent, suggesting the activation of vascular smooth muscle K(ATP) channels by this resin. It is concluded that MMA, HEMA, and TEGDMA interfere with the function of blood vessels by inducing vasorelaxation via different mechanisms, which, depending upon the type of resin, may at least involve the release of nitric oxide and prostanoid(s), and the activation of smooth muscle K(ATP) channels. These phenomena may play a role in tissue homeostasis and certain pathophysiological conditions associated with the application of resin materials to the oral environment.

The effect of aspirin on the periodontal parameter bleeding on probing

BACKGROUND

The absence or presence of bleeding on probing (BOP) is a sign of periodontal health or disease, but the presence of BOP is not an accurate predictor of disease progression. Aspirin is increasingly used in the prevention of cerebrovascular and cardiovascular diseases and is a non-disease factor that may modify bleeding indices given its antithrombolytic activity. The purpose of this double-blind placebo-controlled randomized clinical trial was to study the effect of short-term daily aspirin ingestion on the clinical parameter BOP.

METHODS

A total of 46 periodontally healthy subjects were included in this study: 16 received placebo, 15 low-dose aspirin (81 mg), and 15 regular dose (325 mg) aspirin. Clinical parameters assessed included plaque index, periodontal probing depth, and BOP using an automated pressure-sensitive probe. Measurements were recorded before and after 7-day exposure to placebo and aspirin regimens.

RESULTS

A statistically significant difference in BOP was found in patients with > or = 20% of bleeding sites during the visit prior to placebo or aspirin exposure (n = 11). The group treated with 325 mg aspirin exhibited a moderate yet statistically significant increase in BOP (12.4%) compared to the placebo group (there was no significant difference between the 81 mg aspirin group and placebo). The tendency to bleed was not statistically significant in the group which exhibited <20% (n = 35) of bleeding sites during the visit prior to exposure.

CONCLUSION

Aspirin intake of 325 mg daily for 7 days moderately increased the appearance of bleeding on probing in a population that had > or = 20% BOP sites.

Interaction between piroxicam and azithromycin during distribution to human periodontal tissues

BACKGROUND

Non-steroidal anti-inflammatory drugs and antibiotics are important in the prevention of infections and pain associated with periodontal surgery as well as in the adjunctive therapy of periodontal disease. In this study, patients undergoing oral surgery were treated with piroxicam and azithromycin to examine the interactions of these drugs on periodontal tissues.

METHODS

Sixty-six patients were assigned to 3 groups and treated for 3 days as follows: 1) piroxicam 20 mg/day; 2) azithromycin 500 mg/day; or 3) piroxicam 20 mg/day plus azithromycin 500 mg/day. Samples of blood, saliva, gingiva, and alveolar bone were collected during surgery and at days 0.5, 2.5, 4.5, and 6.5 after last dose. Piroxicam concentrations were assayed by high-performance liquid chromatography and azithromycin concentrations by microbiological assay.

RESULTS

In patients treated with piroxicam alone, the highest drug concentrations were found in plasma at each time point, but consistent piroxicam levels were also detected in gingival samples up to 4.5 days. The combined treatment with piroxicam plus azithromycin was associated with a reduction of piroxicam concentrations in periodontal tissues. In patients receiving azithromycin alone, high drug levels were measured in periodontal tissues up to 6.5 days. This distribution pattern did not vary in patients treated with piroxicam plus azithromycin.

CONCLUSIONS

Treatment with piroxicam or azithromycin alone ensures a favorable distribution of these drugs into periodontal tissues. However, upon combined administration, azithromycin interferes negatively with the periodontal disposition of piroxicam. This interaction might depend on the displacement of piroxicam from acceptor sites at the level of periodontal tissues.

Influence of (S)-ketoprofen and fluoride on caries in rats

OBJECTIVE

Non-steroidal anti-inflammatory agents (e.g., ketoprofen) used topically appear to be effective in reducing bone loss in the ligature model of periodontitis. Ketoprofen, in common with some food preservatives, e.g., benzoate and sorbate, is a weak acid. Fluoride, too, may behave as a weak acid and, similar to the other agents, may exert antibacterial effects. The purpose of the present study was to determine whether a combination of (S)-ketoprofen, an enantiomer of ketoprofen, alone or in combination with fluoride, would suppress Streptococcus sobrinus populations and reduce the incidence of dental caries in rats.

MATERIALS AND METHODS

Toothpastes containing ketoprofen and/or monofluorophosphate were applied to the teeth of six groups of 20 rats twice daily for 5 weeks.

RESULTS

Fewest S. sobrinus were found in the group treated with a paste containing 3% (S)-ketoprofen + 0.1% F. This group also displayed the lowest incidence of smooth surface caries of all groups. Severity of sulcal surface caries was also lowest in this group.

CONCLUSIONS

Results from this study show that the (S) enantiomer of ketoprofen enhances the caries protective effect of fluoride. It is conceivable that this combination could be effective in combating the two most common maladies of the mouth; periodontal disease and dental caries.

Rheumatoid arthritis: a review and suggested dental care considerations

BACKGROUND

Rheumatoid arthritis, or RA, is a chronic multisystem disease of presumed autoimmune etiology. It is estimated that arthritis and other rheumatic conditions affect 42.7 million Americans. Medical complications due to RA and its treatment may affect the provision of oral health care.

METHODS

The authors undertook an extensive review of the English literature relating to RA and dental care. They used primarily MEDLINE searches, which included such key words as "rheumatoid arthritis" and "dental care" and subsequent appropriate subheadings. While the MEDLINE search spanned the years from 1975 to the present, the most recent literature was prioritized. Appropriate medical and dental textbooks were also used. The authors extrapolated information from selected texts based on its relevance to dentistry, oral health and the role of the dental provider in the overall treatment of RA patients.

RESULTS

The authors reviewed nearly 200 articles and seven textbooks. Their determination of the texts' relevance to oral health care was based on content, significance, quality, journal in which articles were published and year of publication. Major features of RA--including its diagnosis, pathophysiology, clinical features and medical treatment--were identified, as well as complications due to treatment modalities and various related oral manifestations and conditions.

CONCLUSIONS

Medical complications due to RA and its treatment can affect oral health care. Oral health care providers need to recognize and identify modifications of dental care based on the medical status of patients with RA. Furthermore, oral health care providers play an important role in the overall care of these patients as it release to early recognition, as well as control of the disease.

CLINICAL IMPLICATIONS

In most patients with RA, the condition will necessitate few or no changes in routine dental care. However, considerations include the patient's ability to maintain adequate oral hygiene, xerostomia and its related complications, the patient's susceptibility to infections, impaired hemostasis, and untoward drug actions and interactions. Patients with RA may require antibiotic prophylaxis owing to joint replacement and/or immune suppression, glucocorticosteroid replacement therapy and modifications in oral hygiene procedures. Intra- and extraoral conditions such as ulcerations, gingival overgrowth, disease-associated periodontitis and temporomandibular pathology also need to be recognized.

Interleukin-1 and tumor necrosis factor antagonists inhibit the progression of inflammatory cell infiltration toward alveolar bone in experimental periodontitis

Periodontal disease is a significant cause of tooth loss in humans and is one of the most prevalent diseases associated with bone loss. Following bacterial colonization, the gingiva becomes inflamed and, in some cases, progresses to destruction of alveolar bone. To investigate the temporal movement of inflammatory cells toward alveolar bone and the role of interleukin-1 (IL-1) and tumor necrosis factor (TNF) in this process, studies were carried out in a Macaca fascicularis primate model of experimental periodontitis. IL-1 and TNF activity was inhibited by local application of soluble receptors to IL-1 and TNF by injection into interdental papillae. The results indicate that following induction of experimental periodontitis, the front of inflammatory cells progresses toward alveolar bone and is associated with osteoclast formation. These processes are inhibited by blockers to IL-1 and TNF. These studies suggest that the conversion from gingivitis to periodontitis is directly associated with the movement of an inflammatory infiltrate toward alveolar bone, and that this activity is at least partially dependent upon IL-1 and/ or TNF.

Risk for periodontal disease in patients with longstanding rheumatoid arthritis

OBJECTIVE

To quantify periodontal disease in rheumatoid arthritis (RA) patients and controls, and to correlate the degree of destruction from periodontal disease and from RA.

METHODS

Fifty RA patients were matched for age, sex, smoking status, and oral hygiene with 101 controls. Correlations between indices of chronic destruction in periodontal disease (gingival attachment loss) and in RA (Larsen radiographic score) were determined.

RESULTS

Patients with longstanding active RA (mean +/- SD 13 +/- 8 years) who were receiving treatment with disease-modifying antirheumatic drugs (n = 46), corticosteroids (n = 38), or nonsteroidal antiinflammatory drugs (n = 43) had a higher rate of gingival bleeding (increased by 50%), greater probing depth (increased by 26%), greater attachment loss (increased by 173%), and higher number of missing teeth (increased by 29%) compared with controls. No correlation was found between the Larsen radiographic score and gingival attachment.

CONCLUSION

Patients with longstanding active RA have a substantially increased frequency of periodontal disease, including loss of teeth, compared with controls. Antiinflammatory treatment interferes with periodontal disease and might have masked a possible correlation between the indices of chronic destruction in RA and periodontal disease.

Short-chain carboxylic-acid-stimulated, PMN-mediated gingival inflammation

This communication reviews the effects of short-chain carboxylic acids on human cells of importance to the periodontium. The central hypothesis is that these acids can alter both cell function and gene expression, and thus contribute to the initiation and prolongation of gingival inflammation. Short-chain carboxylic acids [CH3-(CH2)x-COOH, x < 3] are metabolic intermediates with a broad range of apparently paradoxical biological effects. For example, lactic acid (CH3-CHOH-COOH), a 3-carbon alpha-hydroxy-substituted acid, is widely recognized for its cariogenicity. Lactic acid, however, also occurs in tropical fruits, and is the active ingredient in a variety of anti-wrinkle creams developed by dermatologists. In marked contrast, the unsubstituted 3-carbon propionic acid (CH3-CH2-COOH) is used as a food preservative and is the active principle for one class of non-steroidal anti-inflammatory agents. Interestingly, the addition of one carbon to propionic acid dramatically changes the biological effects. The unsubstituted 4-carbon butyric acid (CH3-CH2-CH2-COOH) is used by hematologists as a de-differentiating agent for the treatment of sickle cell anemia, but by oncologists as a differentiating agent for cancer chemotherapy. Finally, acting either individually or in concert, these acids can increase vascular dilation. Clearly, these acids, while metabolically derived, have a number of very divergent activities which are cell-type-specific (Fig. 1). It may be telling that periodontal bacteria produce these acids in millimolar concentrations, and that these bacteria can be characterized by their acid production profiles. It is no less interesting that these acids occur in the gingival crevices of human subjects with severe periodontal disease at millimolar levels which are > 10-fold higher than those found in mildly diseased subjects, and are undetectable in healthy subjects. Further, when applied directly to healthy human gingiva, short-chain carboxylic acids stimulate a gingival inflammatory response and inflammatory cytokine release. At the cellular level, these acids inhibit proliferation of gingival epithelial and endothelial cells, and inhibit leukocyte apoptosis and function, but can stimulate leukocyte cytokine release. At the molecular level, these acids can stimulate neutrophil gene transcription, translation, and protein expression. Thus, the likelihood is high that these acids, in addition to their cariogenic activity, can promote and prolong gingival inflammation. Our challenge will be to identify the cell or cells of the periodontium which respond to short-chain carboxylic acids, to delineate their responses and the molecular mechanism(s) of these effects, and to categorize the aspects of the inflammatory components which damage and those which protect the host. With this information, it may be possible to begin to rationally identify and test pharmaceutical agents which diminish the harmful aspects, while enhancing the beneficial components, of the inflammatory response.

Osteoclast activation in inflammatory periodontal diseases

OBJECTIVE

In this paper, we review the mechanisms thought to be involved in the activation of osteoclasts in periodontitis.

SUMMARY

Osteoclasts are regulated by both microbial and host factors. Some factors act directly on cells of the osteoclast lineage, whereas others act indirectly through other cell types in the bone environment. The proinflammatory cytokines (interleukins 1 and 6, tumor necrosis factors) have been implicated in the stimulation of osteoclastic resorption. The roles of the immunoregulatory cytoknes (interleukins 2 and 4, interferon gamma) are less clear, but decreased levels of these factors may contribute to periodontitis. A number of lipid mediators may be involved in stimulation of bone resorption. These include bacterial lipopolysaccharide and host-derived platelet-activating factor and prostaglandins. More recently, reactive oxygen intermediates and extracellular nucleotides, both present at sites of inflammation, have been investigated as possible modulators of osteoclast activity. The potential use of antiresorptive therapies in periodontitis is reviewed.

CONCLUSIONS

A wide range of host and bacterial factors contribute to the loss of alveolar bone in periodontitis. However, much remains to be understood about the complex mechanisms through which these factors regulate osteoclast activity. Further studies at the cellular and molecular level will lead to a better understanding of these processes and perhaps suggest new approaches for periodontal therapy.

The significance of bone in periodontal disease

Although the connective tissue attachment represents the key issue in periodontal health or disease and in periodontal therapy, the assessment of alveolar bone changes renders valuable indirect evidence for periodontal stability, progression of disease, or repair mechanisms. In periodontal disease bacterial products trigger host cells to release mediators, which may imbalance the steady state between resorption of bone and apposition of osteoid. Modulation of the hosts prostaglandin or interleukin-I synthesis by drug therapy could support the antimicrobial concept of periodontal therapy. Cross-sectional and long-term assessments of alveolar bone have been used to estimate the progression rate of periodontal disease. Inherent limitations of bone assessments in radiographs have to be considered when drawing conclusions from measurements that represent remodeling in periodontal lesions after therapy. Both bone quantity and quality seem to be of secondary importance with respect to the progression of disease, as well as response to therapy. Other risk factors that affect the microbial ecology and/or the hosts immune system seem to be the primary determinants for the periodontal health status.

Comparison of canine and non-human primate animal models for periodontal regenerative therapy: results following a single administration of PDGF/IGF-I

Two commonly used animal models for evaluating putative periodontal regenerative therapies are the beagle dog model with natural periodontal disease and the non-human primate with ligature-induced attachment loss. The host response, microbiology, and skeletal rates of remodeling of these two models are summarized. In addition, the results of experiments comparing the healing response to periodontal surgery with and without concurrent use of the combination of platelet-derived growth factor (PDGF) and insulin-like growth factor-I (IGF-I) in these models are presented. At 1 month, PDGF/IGF-I administration resulted in a 64.1% and 51.4% increase in new attachment formation in the non-human primate and canine, respectively, while controls (surgery plus placebo) demonstrated 34.1% and 8.6% increases in new attachment formation in the non-human primate and canine models, respectively. Further, application of PDGF/IGF-I stimulated 21.6% and 65% osseous defect fill in the non-human primate and canine, respectively, while controls demonstrated 8.5% and 14.5% osseous defect fill in the non-human primate and canine, respectively. The osseous response in the canine appears greater than that of the non-human primate, and the new attachment formation was more substantial in the non-human primate than the canine. However, in general these data demonstrate a high degree of consistency in the effects of PDGF/IGF-I in promoting periodontal regeneration. Positive results in these two models--the dog with natural periodontal disease and the non-human primate with ligature-induced attachment loss--justify human clinical trial testing of a putative regenerative therapy.