Tissue localization of Actinobacillus actinomycetemcomitans in human periodontitis. I. Light, immunofluorescence and electron microscopic studies

Grade C Molar-Incisor Pattern Periodontitis in Young Adults: What Have We Learned So Far?

Grade C molar-incisor pattern periodontitis (C-MIP) is a disease that affects specific teeth with an early onset and aggressive progression. It occurs in systemically healthy patients, mostly African descendants, at an early age, with familial involvement, minimal biofilm accumulation, and minor inflammation. Severe and rapidly progressive bone loss is observed around the first molars and incisors. This clinical condition has been usually diagnosed in children and young adults with permanent dentition under 30 years of age. However, this disease can also affect the primary dentition, which is not as frequently discussed in the literature. Radiographic records have shown that most patients diagnosed in the permanent dentition already presented disease signs in the primary dentition. A hyperresponsive immunological profile is observed in local (gingival crevicular fluid-GCF) and systemic environments. Siblings have also displayed a heightened inflammatory profile even without clinical signs of disease. A. actinomycetemcomitans has been classified as a key pathogen in C-MIP in both dentitions. Scaling and root planning associated with systemic antibiotics is the current gold standard to treat C-MIP, leading to GCF biomarker reduction, some systemic inflammatory response modulation and microbiome profile changes to a healthy-site profile. Further studies should focus on other possible disease-contributing risk factors.

Effect of Probiotics Lactobacillus rhamnosus and Lactobacillus plantarum on Caries and Periodontal Diseases: A Systematic Review

Caries and periodontitis are the most prevalent oral diseases worldwide. Major factors contributing to the development of these oral conditions include poor oral hygiene, dental biofilm formation, high carbohydrates diet, smoking, other systemic diseases, and genetic factors. Various preventive measures have been established to mitigate the risk of caries and periodontal disease development. The present review aims to discuss the role of the probiotics Lactobacillus rhamnosus and Lactobacillus plantarum in the prevention and treatment of caries and periodontal diseases. The study was conducted in accordance with PRISMA guidelines and was registered on PROSPERO. The search involved PubMed, Web of Science, and Scopus and considered the PICO format. Studies were screened by two reviewers independently, and disagreements were solved by consensus with a third reviewer. Data extraction included details about the type of probiotics, strains, and purpose of administration. A total of 15 RCTs were included, of which just 1 was about tooth cavities. Overall, 87% of the included studies were good-quality papers regarding the Jadad Scale. Several studies agreed on the potential of probiotics L. rhamnosus and L. plantarum, both alone and combined, to prevent and improve clinical outcomes in caries and periodontal treatments, weaker evidence is provided for the microbiological benefit.

Europe's contribution to the evaluation of the use of systemic antimicrobials in the treatment of periodontitis

This narrative review celebrates Europe's contribution to the current knowledge on systemically administered antimicrobials in periodontal treatment. Periodontitis is the most frequent chronic noncommunicable human disease. It is caused by dysbiotic bacterial biofilms and is commonly treated with subgingival instrumentation. However, some sites/patients do not respond adequately, and its limitations and shortcomings have been recognized. This has led to the development of alternative or adjunctive therapies. One is the use of antimicrobials to target bacteria in subgingival biofilms in the periodontal pocket, which can be targeted directly through the pocket entrance with a locally delivered antibiotic or systemically by oral, intravenous, or intramuscular methods. Since the early 20th century, several studies on systemic antibiotics have been undertaken and published, especially between 1990 and 2010. Europe's latest contribution to this topic is the first European Federation of Periodontology, S3-level Clinical Practice Guideline, which incorporates recommendations related to the use of adjuncts to treat stage I-III periodontitis. Understanding the etiopathogenesis of periodontal diseases, specifically periodontitis, has influenced the use of systemic periodontal antibiotic therapy. Randomized clinical trials and systematic reviews with meta-analyses have demonstrated the clinical advantages of adjunctive systemic antimicrobials. However, current recommendations are restrictive due to concerns about antibiotic misuse and the increase in microbial antibiotic resistance. European researchers have contributed to the use of systemic antimicrobials in the treatment of periodontitis through clinical trials and by providing rational guidelines. Nowadays, European researchers are exploring alternatives and directing clinical practice by providing evidence-based guidelines to limit the use of systemic antimicrobials.

Comparative Evaluation of Cost-Effectiveness, Clinical and Microbiological Parameters of Systemic Antibiotics Versus Local Drug Delivery in Aggressive Periodontitis

BACKGROUND

Periodontitis is a biofilm-associated inflammatory disease of the periodontium in which microbial component contributes to its initiation that mainly includes chronic periodontitis and aggressive periodontitis (AgP).

AIM

The present study aimed to ascertain a cost-effective treatment approach in AgP with minimal side effects by comparing systemic antibiotics (SA) and local drug delivery (LDD) as an adjunct to scaling and root planning (SRP). Furthermore, the objectives were to analyze its effect on clinical and microbial parameters.

MATERIALS AND METHODS

The participants were randomly divided into two groups A and B with eleven participants each. Group A was administered with Chlosite Gel [LDD] whereas group B with amoxicillin (AMX) 500 mg + metronidazole (MTZ) 400 mg [SA] thrice daily for 14 days. Clinical parameters such as plaque index (PI), gingival index (GI), clinical attachment level (CAL), and pocket probing depth (PPD)] were recorded at baseline and three months postoperatively. Microbiological parameters i.e Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) counts were also measured at baseline and after three months.

RESULTS

Statistically significant difference was observed in all clinical parameters i.e. PI, GI, CAL, and PPD after three months follow-up in groups A and B. Reduced bacterial load i.e. Aa and Pg was significant at three months in both the groups. However, on comparing the total expenditure of both the groups, group A ranged from 920-1480 ₹ while in group B it ranged from 330-360 ₹. Hence, lower expenditure in group B (3.7 fold) compared to group A was evident.

CONCLUSIONS

Cost-effective approach recommended in the present study is mainly to promote awareness among periodontal patients in the public and private sectors, who refuse to get dental treatment due to fear of high expenditure. This can be attained by incorporating SA as an alternative to LDD in AgP patients.

Comparing the efficiency of Er,Cr:YSGG laser and diode laser for the treatment of generalized aggressive periodontitis

BACKGROUND

This study aims to determine the effects of Er,Cr:YSGG and diode laser treatments on IL-1β, IL-8, and TNF-α levels in patients with generalized aggressive periodontitis.

METHODS

Twenty-six generalized aggressive periodontitis patients were enrolled in the study. We performed three treatment models: "scaling and root planning (SRP-only)," "SRP + Er,Cr:YSGG laser," and "SRP + diode laser." Each experimental quadrant was randomly allocated to the control group or the test group. The IL-1β, IL-8, and TNF-α levels were analyzed with an enzyme-linked immune-sorbent assay.

RESULTS

When the baseline and post-treatment IL-1β, IL-8, and TNF-α levels were compared, the most significant difference was observed in the SRP + Er,Cr:YSGG group and the least difference was observed in the SRP-only group.

CONCLUSIONS

The use of Er,Cr:YSGG laser as an addition to the conventional mechanical periodontal treatment was found to be more successful than the diode laser + SRP use in aggressive periodontitis treatment.

The effects of non-surgical periodontal therapy on neutrophil elastase and elastase alpha-1 proteinase inhibitor levels in GCF in periodontitis patients with or without acute coronary syndrome

OBJECTIVE

Periodontitis may contribute to vascular damage, resulting in the destabilization of atherosclerotic plaque leading to acute coronary syndrome (ACS). In this study, we explored the effect of non-surgical periodontal treatment (NSPT) on cardiovascular blood biomarkers and gingival crevicular fluid (GCF) neutrophil elastase (NE) and α1-proteinase inhibitor (α-1PI) levels in periodontitis (P) participants with and without ACS.

MATERIALS AND METHODS

Medical and dental examinations were performed to diagnose ACS and periodontitis, respectively. Seventeen patients with diagnosis of ACS and periodontitis were included in this study, as a test group (group ACS). Twenty-six age and sex-matched control patients with periodontitis (group P) were otherwise systemically healthy. Both groups received NSPT. Plasma levels of cholesterol, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), C-reactive protein (CRP), GCF NE activity, GCF α₁-PI levels, and GCF NE/α1-PI rates were measured at baseline, at1^st and 3^rd months after NSPT.

RESULTS

GCF NE activity/time (μU/30s) decreased significantly at 3^rd month compared to baseline values in the Group P after NSPT. First and 3^rd months after NSPT, in the Group P GCF α₁-PI activity/time (pg/30s) was significantly higher than the Group ACS. Moreover GCF NE/α₁-PI rates decreased significantly compared to baseline values at 1^st and 3^rd months after NSPT in the group P.

CONCLUSION

NSPT yields decrease in NE/α₁-PI rates. NE and its possible interactions with α₁-PI may play a crucial role in both periodontitis and ACS. GCF α1PI activity/time (U/30s) can be a potential biomarker in management of periodontitis associated with ACS.

CLINICAL RELEVANCE

The GCF α1-PI reduction may alter the immune-inflammatory response in patients with periodontitis and thus increase the risk of ACS.

TRIAL REGISTRATION

Thai Clinical Trials.gov (NCT04785235).

Mast cells exhibit intracellular microbicidal activity against Aggregatibacter actinomycetemcomitans

BACKGROUND AND OBJECTIVE

Several studies have demonstrated that mast cells are equipped with versatile tools to combat and kill bacteria. Additionally, mast cells produce and secrete a variety of mediators, which either regulate the host's immune system or directly attack bacteria. In this study, the intracellular microbicidal capacity of mast cells against Aggregatibacter actinomycetemcomitans was evaluated.

METHODS

Murine mast cells were challenged in vitro with A actinomycetemcomitans for 3, 5, 10, and 24 hours. Subsequently, the colony-forming units were counted. Additionally, the production and release of nitric oxide and hydrogen peroxide were analyzed by DAF-FM diacetate, the Griess reaction, and the Amplex Red kit, respectively. Cell death was evaluated using FITC Annexin V and propidium iodide staining.

RESULTS

Mast cells are able to efficiently eliminate periodontopathogen, with best results after 10 hours of intracellular challenge. The production/release of nitric oxide-and to a lesser extent of hydrogen peroxide-by mast cells was in agreement with its microbicidal capacity. Ninety percent of the mast cells  maintained their cellular viability even after 24 hours of bacterial challenge.

CONCLUSIONS

This is-to the best of our knowledge-the first report to describe the intracellular microbicidal activity of mast cells against A actinomycetemcomitans, concerning the production and release of potentially bactericidal substances. Further, the low number of cell deaths confirms that the decreased number of colony-forming units was due to the higher antimicrobial activity of mast cells. The results highlight the importance of these cells in the defense mechanisms of biofilm-induced periodontal disease.

Aggregatibacter actinomycetemcomitans Biofilm Reduces Gingival Epithelial Cell Keratin Expression in an Organotypic Gingival Tissue Culture Model

Epithelial cells express keratins, which are essential for the structural integrity and mechanical strength of the cells. In the junctional epithelium (JE) of the tooth, keratins such as K16, K18, and K19, are expressed, which is typical for non-differentiated and rapidly dividing cells. The expression of K17, K4, and K13 keratins can be induced by injury, bacterial irritation, smoking, and inflammation. In addition, these keratins can be found in the sulcular epithelium and in the JE. Our aim was to estimate the changes in K4, K13, K17, and K19 expression in gingival epithelial cells exposed to Aggregatibacter actinomycetemcomitans. An organotypic gingival mucosa and biofilm co-culture was used as a model system. The effect of the biofilm after 24 h was assessed using immunohistochemistry. The structure of the epithelium was also studied with transmission electron microscopy (TEM). The expression of K17 and K19, as well as total keratin expression, decreased in the suprabasal layers of epithelium, which were in close contact with the A. actinomycetemcomitans biofilm. The effect on keratin expression was biofilm specific. The expression of K4 and K13 was low in all of the tested conditions. When stimulated with the A. actinomycetemcomitans biofilm, the epithelial contact site displayed a thick necrotic layer on the top of the epithelium. The A. actinomycetemcomitans biofilm released vesicles, which were found in close contact with the epithelium. After A. actinomycetemcomitans irritation, gingival epithelial cells may lose their resistance and become more vulnerable to bacterial infection.

Virulence and Pathogenicity Properties of Aggregatibacter actinomycetemcomitans

Aggregatibacter actinomycetemcomitans is a periodontal pathogen colonizing the oral cavity of a large proportion of the human population. It is equipped with several potent virulence factors that can cause cell death and induce or evade inflammation. Because of the large genetic diversity within the species, both harmless and highly virulent genotypes of the bacterium have emerged. The oral condition and age, as well as the geographic origin of the individual, influence the risk to be colonized by a virulent genotype of the bacterium. In the present review, the virulence and pathogenicity properties of A. actinomycetemcomitans will be addressed.

Tools of Aggregatibacter actinomycetemcomitans to Evade the Host Response

Periodontitis is an infection-induced inflammatory disease that affects the tooth supporting tissues, i.e., bone and connective tissues. The initiation and progression of this disease depend on dysbiotic ecological changes in the oral microbiome, thereby affecting the severity of disease through multiple immune-inflammatory responses. Aggregatibacter actinomycetemcomitans is a facultative anaerobic Gram-negative bacterium associated with such cellular and molecular mechanisms associated with the pathogenesis of periodontitis. In the present review, we outline virulence mechanisms that help the bacterium to escape the host response. These properties include invasiveness, secretion of exotoxins, serum resistance, and release of outer membrane vesicles. Virulence properties of A. actinomycetemcomitans that can contribute to treatment resistance in the infected individuals and upon translocation to the circulation, also induce pathogenic mechanisms associated with several systemic diseases.

Effects of Er,Cr:YSGG and Diode Lasers on Clinical Parameters and Gingival Crevicular Fluid IL-1β and IL-37 Levels in Generalized Aggressive Periodontitis

Aim

The objective of the current study is to analyze the correlation between cytokine levels and periodontal parameters in aggressive periodontitis patients before and after periodontal treatment that was performed by using two different laser therapies.

Materials and Methods

Twenty-six generalized aggressive periodontitis patients were treated with three different methods (SRP, SRP+diode laser, and SRP+Er,Cr:YSGG laser) applied to three different half-jaws in the same patients. Pre- and posttreatment clinical periodontal parameters and GCF IL-1β and IL-37 levels were measured.

Results

There was a statistically significant decrease (p < 0.05) between pretreatment and posttreatment clinical periodontal parameters and IL-1β and IL-37 levels. When the reduction rates of IL-37 and IL-1β levels after treatment were evaluated, the decrease in IL-37 and IL-1β levels after treatment was lowest in the SRP group and highest in the SRP+Er,Cr:YSGG group. In addition, the amount of decrease in IL-1β in SRP+diode and SRP+Er,Cr:YSGG groups was found to be higher than that in IL-37. Furthermore, there was a positive correlation between IL-37 and IL-1β in all groups (p < 0.01).

Conclusion

Er,Cr:YSGG laser is more effective than diode laser for the treatment of aggressive periodontitis. IL-37 and IL-1β are cytokines that function together and thus must be evaluated together.

The Anti-biofilm Activity of Nanometric Zinc doped Bioactive Glass against Putative Periodontal Pathogens: An in vitro Study

Colonization of periodontal pathogens on the surgical sites is one of the primary reasons for the failure of regenerative periodontal therapies. Bioactive glasses (BGs) owing to their favorable structural and antimicrobial properties have been proposed as promising materials for the reconstruction of periodontal and peri-implant bone defects. This study aimed to investigate the antibiofilm activity of zinc-doped BG (Zn/BG) compared with 45S5 Bioglass® (BG®) on putative periodontal pathogens. In this in vitro experimental study, the nano BG doped with 5-mol% zinc and BG® were synthesized by sol-gel method. Mono-species biofilms of Aggregatibacter actinomycetemcomitans (A. a), Porphyromonas gingivalis (P. g), and Prevotella intermedia (P. i)were prepared separately in a well-containing microplate. After 48 hours of exposure to generated materials at 37°C, the anti-biofilm potential of the samples was studied by measuring the optical density (OD) at 570nm wavelengths with a microplate reader. Two-way ANOVA then analyzed the results. Both Zn/BG and BG® significantly reduced the biofilm formation ability of all examined strains after 48 hours of incubation (P=0.0001). Moreover, the anti-biofilm activity of Zn/BG was significantly stronger than BG® (P=0.0001), which resulted in the formation of a weak biofilm (OD<1) compared with a moderately adhered biofilm observed with BG® (1<OD<2). Zn/BG showed a significant inhibitory effect on the biofilm formation of all examined periodontal pathogens. Given the enhanced regenerative and anti-biofilm properties of this novel biomaterial, further investigations are required for its implementation in clinical situations.

Periodontal bacterial invasion and infection: contribution to atherosclerotic pathology

OBJECTIVE

The objective of this review was to perform a systematic evaluation of the literature reporting current scientific evidence for periodontal bacteria as contributors to atherosclerosis.

METHODS

Literature from epidemiological, clinical and experimental studies concerning periodontal bacteria and atherosclerosis were reviewed. Gathered data were categorized into seven "proofs" of evidence that periodontal bacteria: 1) disseminate from the oral cavity and reach systemic vascular tissues; 2) can be found in the affected tissues; 3) live within the affected site; 4) invade affected cell types in vitro; 5) induce atherosclerosis in animal models of disease; 6) non-invasive mutants of periodontal bacteria cause significantly reduced pathology in vitro and in vivo; and 7) periodontal isolates from human atheromas can cause disease in animal models of infection.

RESULTS

Substantial evidence for proofs 1 to 6 was found. However, proof 7 has not yet been fulfilled.

CONCLUSIONS

Despite the lack of evidence that periodontal bacteria obtained from human atheromas can cause atherosclerosis in animal models of infection, attainment of proofs 1 to 6 provides support that periodontal pathogens can contribute to atherosclerosis.

Periodontal bacterial invasion and infection: contribution to atherosclerotic pathology

OBJECTIVE

The objective of this review was to perform a systematic evaluation of the literature reporting current scientific evidence for periodontal bacteria as contributors to atherosclerosis.

METHODS

Literature from epidemiological, clinical and experimental studies concerning periodontal bacteria and atherosclerosis were reviewed. Gathered data were categorized into seven "proofs" of evidence that periodontal bacteria: 1) disseminate from the oral cavity and reach systemic vascular tissues; 2) can be found in the affected tissues; 3) live within the affected site; 4) invade affected cell types in vitro; 5) induce atherosclerosis in animal models of disease; 6) non-invasive mutants of periodontal bacteria cause significantly reduced pathology in vitro and in vivo; and 7) periodontal isolates from human atheromas can cause disease in animal models of infection.

RESULTS

Substantial evidence for proofs 1 to 6 was found. However, proof 7 has not yet been fulfilled.

CONCLUSIONS

Despite the lack of evidence that periodontal bacteria obtained from human atheromas can cause atherosclerosis in animal models of infection, attainment proofs 1 to 6 provides support that periodontal pathogens can contribute to atherosclerosis.

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

The presence of bacteria within the pocket epithelium and underlying connective tissue in gingival biopsies from patients with periodontitis has been reported using various methods, including electron microscopy, immunohistochemistry or immunofluorescence using bacteria-specific antibodies, and fluorescent in situ hybridization (FISH) using a fluorescence-labeled oligonucleotide probe. Nevertheless, these methods are not widely used due to technical limitation or difficulties. Here a method to localize bacteria within paraffin-embedded tissues using DIG-labeled DNA probes has been introduced. The paraffin-embedded tissues are the most common form of biopsy tissues available from pathology banks. Bacteria can be detected either in a species-specific or universal manner. Bacterial signals are detected as either discrete forms (coccus, rod, fusiform, and hairy form) of bacteria or dispersed forms. The technique allows other histological information to be obtained: the epithelia, connective tissue, inflammatory infiltrates, and blood vessels are well distinguished. This method can be used to study the role of bacteria in various diseases, such as periodontitis, cancers, and inflammatory immune diseases.

Hyaluronic Acid as an adjunct to scaling and root planing in chronic periodontitis. A randomized clinical trail

AIM

AIM of the present study was to evaluate the adjunctive effect of local application of hyaluronon gel following scaling and root planing (SRP) in chronic periodontitis patients.

MATERIALS AND METHODS

In this randomized split mouth study 33 subjects with chronic periodontitis were evaluated after full mouth SRP. In the test sites hyaluronon gel was applied immediately after SRP and one week post therapy, the control sites were treated with SRP alone. Bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) were recorded at baseline, 4 wk and 12 wk.

RESULTS

Significant reduction in BOP scores was observed in both the groups at 12weeks (p<0.001). The hyaluronon group showed a greater reduction in BOP (p<0.001). In the hyaluronon group the mean PPD at baseline was 6.33±0.09 which reduced to 2.49±0.51 at 12 weeks which was statistically significant (p<0.001). In the control group the mean PPD at baseline was 6.09±1.26 which reduced to 4.36±1.29 at 12 weeks which was statistically significant (p<0.001). The CAL measurements showed a significant difference between the groups (p<0.001) at 12 wk post therapy.

CONCLUSION

Hyaluronic Acid (HA) has a beneficial effect on periodontal health in patients with chronic Periodontitis. HA appears to be a suitable candidate as an adjunct to SRP in chronic periodontitis patients.

Breaking the Gingival Epithelial Barrier: Role of the Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin in Oral Infectious Disease

The Gram-negative bacterium Aggregatibacter actinomycetemcomitans is part of the HACEK group that causes infective endocarditis, a constituent of the oral flora that promotes some forms of periodontal disease and a member of the family of species that secrete a cytolethal distending toxin (Cdt). The family of bacteria that express the cdt genes participate in diseases that involve the disruption of a mucosal or epithelial layer. In vitro studies have shown that human gingival epithelial cells (HGEC) are native targets of the Cdt that typically induces DNA damage that signals growth arrest at the G₂/M interphase of the cell cycle. The gingival epithelium is an early line of defense in the oral cavity against microbial assault. When damaged, bacteria collectively gain entry into the underlying connective tissue where microbial products can affect processes and pathways in infiltrating inflammatory cells culminating in the destruction of the attachment apparatus of the tooth. One approach has been the use of an ex vivo gingival explant model to assess the effects of the Cdt on the morphology and integrity of the tissue. The goal of this review is to provide an overview of these studies and to critically examine the potential contribution of the Cdt to the breakdown of the protective gingival barrier.

Microbial analysis of subgingival plaque samples compared to that of whole saliva in patients with periodontitis

BACKGROUND

The detection of special bacterial species in patients with periodontitis is considered to be useful for clinical diagnosis and treatment. The collection of subgingival plaque samples is the common way for the determination of periodontopathic bacteria. However, recently, salivary analysis has been discussed as an advantageous future diagnostic method for periodontitis because it offers simple quantitative sampling and the possibility to assess various bacteria. The aim of this cross-sectional study is to investigate whether there is a correlation between the results of different bacterial species in saliva and subgingival plaque samples from individuals with aggressive periodontitis (AgP) and chronic periodontitis (CP).

METHODS

Whole saliva and subgingival plaque samples from the deepest pocket of each quadrant were collected from 43 patients with CP and 33 patients with AgP. Twenty different bacterial species from both samplings were determined by the 16S ribosomal RNA-based polymerase chain reaction with microarray technique.

RESULTS

All bacterial species were detected in salivary and subgingival plaque samples. For Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, as well as Actinomyces viscosus, Campylobacter rectus/showae, Prevotella intermedia, Parvimonas micra, Eubacterium nodatum, and Campylobacter gracilis, a significant positive correlation between salivary and subgingival plaque samples was detected in patients with both types of periodontitis. There were no significant differences in bacteria in salivary and subgingival plaque samples between AgP and CP.

CONCLUSION

Salivary analysis might be discussed as a potential alternative to subgingival plaque sampling for microbiologic analysis in both AgP and CP.

Effect of gingivitis on azithromycin concentrations in gingival crevicular fluid

BACKGROUND

Macrolide antibiotics yield high concentrations in inflamed tissue, suggesting that their levels in gingival crevicular fluid (GCF) could be increased at gingivitis sites. However, the increased volume of GCF associated with gingivitis could potentially dilute macrolides. To determine whether these assumptions are correct, the bioavailability of systemically administered azithromycin was compared in GCF from healthy and gingivitis sites.

METHODS

Experimental gingivitis was induced in one maxillary posterior sextant in nine healthy individuals. Contralateral healthy sextants served as controls. Participants ingested 500 mg azithromycin, followed by a 250-mg dose 24 hours later. Four hours after the second dose, plaque was removed from experimental sites. GCF was collected from eight surfaces in both the experimental and control sextants and pooled separately. GCF samples were subsequently collected on days 2, 3, 8, and 15, and azithromycin content was determined by agar diffusion bioassay.

RESULTS

On days 2 and 3, the pooled GCF volume at experimental sites was significantly higher than at control sites (P <0.01), and the total azithromycin mass in 30-second GCF samples pooled from experimental sites was significantly higher than at control sites (P <0.02). However, there were no significant differences in azithromycin concentration between the experimental and control pools at any point. Concentrations exceeded 7.3 μg/mL on day 2 and 2.5 μg/mL on day 15.

CONCLUSION

Azithromycin concentrations are similar in GCF from gingivitis sites and healthy sites, suggesting that the processes that regulate GCF azithromycin concentration can compensate for local inflammatory changes.

Cytolethal distending toxin damages the oral epithelium of gingival explants

The cytolethal distending toxin (Cdt), expressed by the periodontal pathogen Aggregatibacter actinomycetemcomitans, inhibits the proliferation of cultured epithelial cells by arresting the cell cycle. The gingival epithelium is an early line of defense against microbial assault. When damaged, bacteria collectively gain entry into underlying connective tissue where microbial products can affect infiltrating inflammatory cells, leading to the destruction of the attachment apparatus. Histological evaluation of rat and healthy human gingival tissue exposed ex vivo to the Cdt for 36 and 18 hours, respectively, revealed extensive detachment of the keratinized outer layer and distention of spinous and basal cells in the oral epithelium. Treated human tissue also exhibited disruption of rete pegs and dissolution of cell junctions. Cells in the connective tissue appeared unaffected. Primary gingival epithelial cells, but not gingival fibroblasts, isolated from the same healthy human tissue were cell-cycle-arrested when treated with the toxin. These findings provide new evidence that the Cdt severely damages the oral epithelium, ex vivo, by specifically targeting epithelial cells, in situ. The Cdt shows preferential targeting of the epithelium as opposed to connective tissue in animal and human gingival explant models.

ABBREVIATIONS

cytolethal distending toxin (Cdt), connective tissue (CT), 4',6-diamidino-2-phenylindole (DAPI), human gingival epithelial cells (HGEC), human gingival explants (HGX), human gingival fibroblasts (HGF), junctional epithelium (JE), oral epithelium (OE), rete pegs (RP), sulcular epithelium (SE).

Influence of different biomaterials on the viability of Aggregatibacter actinomycetemcomitans

OBJECTIVES

The aim of the present in vitro study was to evaluate the effects of different biomaterials used for regenerative periodontal surgery on the growth of the periodontopathogen Aggregatibacter actinomycetemcomitans.

METHODS

Three commercially available biomaterials of synthetic origin (hydroxyapatite/beta-tricalcium phosphate, nanostructured hydroxyapatite paste, oily calcium hydroxide suspension), a bovine-derived xenograft as well as an enamel matrix derivative (EMD) were added in different concentrations to calibrated suspensions of A. actinomycetemcomitans ATCC 43718/33384 (serotype b/c). Equal aliquots (0.1 ml) for the viability assay were taken after 5 min, 1h, 3h, 8h and 24h, plated on blood agar and incubated in an anaerobic environment for 48 h at 37°C. Viable cell counts were expressed as colony forming units (cfu)/0.1 ml.

RESULTS

The results demonstrated that none of the investigated biomaterials could inhibit the growth of A. actinomycetemcomitans serotype b. A marked growth reduction of A. actinomycetemcomitans serotype c was observed in the presence of oily calcium hydroxide suspension and nanostructured hydroxyapatite. In contrast, no significant growth inhibition could be observed in the presence of hydroxyapatite/beta-tricalcium phosphate, enamel matrix derivative and bovine-derived xenograft.

CONCLUSIONS

The results of the present study suggest that none of the investigated biomaterials possesses antimicrobial properties against A. actinomycetemcomitans serotype b. Therefore, the use of these biomaterials for regenerative procedures should be weighted critically in the presence of A. actinomycetemcomitans serotype b.

Azithromycin concentrations in blood and gingival crevicular fluid after systemic administration

BACKGROUND

Azithromycin is a macrolide antibiotic that is active against several periodontal pathogens. Macrolides are taken up and concentrated inside gingival fibroblasts, which could influence their pharmacokinetics. This study tests the hypothesis that steady-state levels of azithromycin are higher and more sustained in gingival crevicular fluid (GCF) than in serum.

METHODS

Four healthy patients received an initial dose of 500-mg azithromycin followed by 250-mg doses on each of the next 2 days. Serum and GCF samples were obtained 2 hours after the last dose on day 2, and on days 4 and 7. GCF samples were collected from maxillary posterior sites with paper strips. The strips were pooled and eluted with high-purity water. After extraction, the azithromycin content of the serum samples and GCF eluates was determined with an agar diffusion bioassay.

RESULTS

On days 2, 4, and 7, the concentrations of azithromycin in blood serum were 0.22 ± 0.02, 0.08 ± 0.02, and 0.04 ± 0.01 μg/mL, respectively. The concentrations in GCF were 8.82 ± 1.25, 7.90 ± 1.72, and 7.38 ± 1.15 μg/mL, respectively. Mean GCF levels were significantly higher than mean serum levels (P ≤0.02; paired t test).

CONCLUSIONS

The findings demonstrate that the pharmacokinetic profiles of azithromycin are different in GCF and serum. At steady state, azithromycin concentrations in GCF were higher and more sustained than those in serum. Based on previous studies, the levels observed in GCF were above the minimal inhibitory concentration for Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Porphyromonas gingivalis, and Prevotella intermedia.

Azithromycin decreases crevicular fluid volume and mediator content

Azithromycin enhances the response to root planing and produces anti-inflammatory effects in treating chronic lung disease. This led us to hypothesize that azithromycin inhibits inflammatory mediator production in gingiva, leading to decreased gingival crevicular fluid (GCF) volume. To test this hypothesis, ten periodontally healthy volunteers received azithromycin every 24 hours for 48 hours. GCF samples were collected from 12 maxillary interproximal sites prior to azithromycin (baseline) and 2, 4, 7, and 14 days later. Samples were assayed for IL-1beta, IL-8, TNF-alpha, VEGF, IL-6, and IL-10. With azithromycin treatment, GCF volume decreased significantly on days 2 through 7 (P < 0.05), but increased toward baseline levels on day 14. This was accompanied by a transient decrease in the content of IL-1beta, IL-8, TNF-alpha, and VEGF (P < 0.05). IL-6 and IL-10 were not detected. Since plaque was absent throughout the study, the findings suggest that azithromycin produces anti-inflammatory effects in gingiva.

The relationship between physiologic halitosis and periodontopathic bacteria of the tongue and gingival sulcus

To determine the influence of oral status on halitosis, the relationship between halitosis and periodontopathic bacteria present in plaque on the tongue and the subgingival sulcus was examined in 62 periodontally healthy adults. Halitosis indicators used were the organoleptic score; gas chromatography results [total volatile sulfur compounds (VSCs) = H(2)S + CH(3)SH + (CH(3))(2)S]; Halimeter values; and the results of three clinical tests, plaque control record (PlCR), plaque index (PlI), and tongue coat status. Significant correlations with organoleptic scores was observed for PlCR, PlI, tongue coat status, VSC amounts, and Halimeter values, indicating that halitosis in periodontally healthy subjects tended to originate from tongue plaque deposits. Polymerase chain reaction analysis was used to detect six periodontopathic bacteria (Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola) from the tongue and subgingival plaque. Significant effects on the organoleptic scores, tongue coat status, total VSC, H(2)S and CH(3)SH amounts, and Halimeter values were observed only for T. denticola and F. nucleatum and only in the tongue plaque, not in the subgingival plaque. Thus, therapies developed to inhibit the growth of these bacteria may lead to future treatments of halitosis.

Cardiovascular disease parameters in periodontitis

BACKGROUND

Recently, there has been an increasing in the impact of oral health on atherosclerosis and subsequent cardiovascular disease. The aim of this study is to investigate the association between chronic periodontitis and cardiovascular risk markers.

METHODS

Forty patients with periodontitis and 40 healthy gender-, body mass index-, and age-matched individuals were compared by measuring total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, levels of cytokines, antibodies against oxidized low-density lipoprotein, thiobarbituric acid reactive substances, total and differential white blood cell counts, and the non-linear index of refraction.

RESULTS

The levels of triglycerides and high-density lipoprotein in periodontitis patients were significantly higher and lower, respectively (P = 0.002 and P = 0.0126), compared to controls. Total cholesterol, low-density lipoprotein, and lipid peroxide levels were the same in both groups (P = 0.2943, P = 0.1284, and P = 0.067, respectively). Interleukin (IL)-6 and -8, antibodies against oxidized low-density lipoprotein, and leukocyte and neutrophil counts were significantly higher in periodontitis patients (P <0.05). The value of the non-linear index of refraction of low-density lipoprotein solutions was higher in the controls (P = 0.015) compared to individuals with periodontitis.

CONCLUSION

Our results confirmed and further strengthened the suggested association between coronary artery disease and periodontitis.

Persistence of extracrevicular bacterial reservoirs after treatment of aggressive periodontitis

BACKGROUND

The purpose of this study was to test the hypothesis that periodontal pathogens associated with aggressive periodontitis persist in extracrevicular locations following scaling and root planing, systemic antibiotics, and antimicrobial rinses.

METHODS

Eighteen patients with aggressive periodontitis received a clinical examination during which samples of subgingival plaque and buccal epithelial cells were obtained. Treatment consisted of full-mouth root planing, systemic antibiotics, and chlorhexidine rinses. Clinical measurements and sampling were repeated at 3 and 6 months. Quantitative polymerase chain reaction determined the number of Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Prevotella intermedia, Porphyromonas gingivalis, Tannerella forsythia (previously T. forsythensis), and Treponema denticola in the plaque. Fluorescence in situ hybridization and confocal microscopy determined the extent of intracellular invasion in epithelial cells.

RESULTS

Clinical measurements improved significantly following treatment. All bacterial species except P. gingivalis were significantly reduced in plaque between baseline and 3 months. However, all species showed a trend to repopulate between 3 and 6 months. This increase was statistically significant for log T. denticola counts. All species were detected intracellularly. The percentage of cells infected intracellularly was not affected by therapy.

CONCLUSIONS

The 6-month increasing trend in the levels of plaque bacteria suggests that subgingival recolonization was occurring. Because the presence of these species within epithelial cells was not altered after treatment, it is plausible that recolonization may occur from the oral mucosa. Systemic antibiotics and topical chlorhexidine did not reduce the percentage of invaded epithelial cells. These data support the hypothesis that extracrevicular reservoirs of bacteria exist, which might contribute to recurrent or refractory disease in some patients.

Porphyromonas gingivalis RgpA-Kgp proteinase-adhesin complexes penetrate gingival tissue and induce proinflammatory cytokines or apoptosis in a concentration-dependent manner

The RgpA-Kgp proteinase-adhesin complexes of Porphyromonas gingivalis were observed, using immunostaining, in human gingival tissue associated with periodontitis but not in healthy tissue. The staining pattern suggested a concentration gradient from the subgingival plaque into the subjacent gingival connective tissue. Intense immunostaining was observed in areas displaying gross disturbance of tissue architecture. P. gingivalis cells and the RgpA-Kgp complexes at low concentrations were shown to stimulate secretory intercellular adhesion molecule 1, interleukin-8 (IL-8), IL-6, and macrophage chemoattractant protein secretion from cultured human epithelial (KB) and fibroblast (MRC-5) cells. However, at high concentrations a reduction in the level of these mediators was observed. In contrast, macrophage inflammatory protein 1alpha and IL-1alpha were stimulated only at high P. gingivalis cell concentrations. P. gingivalis cells and the RgpA-Kgp complexes were shown to induce apoptosis in KB and MRC-5 cells in a time- and dose-dependent manner. These data suggest that the RgpA-Kgp complexes penetrate the gingival connective tissue; at low concentrations distal from the plaque the complexes stimulate the secretion of proinflammatory mediators, while at high concentrations proximal to the plaque they induce apoptosis and attenuate the secretion of proinflammatory mediators.

Clarithromycin transport by gingival fibroblasts and epithelial cells

Macrolide antibiotics penetrate cells, but the mechanism by which this occurs is unclear. The objective of this study was to characterize the mechanisms of clarithromycin uptake by gingival fibroblasts and oral epithelium. Cultured human gingival fibroblasts and SCC-25 cells were incubated with [(3)H]-clarithromycin. We assayed clarithromycin transport by measuring cell-associated radioactivity over time. Fibroblasts and epithelial cells rapidly accumulated clarithromycin, attaining steady-state intracellular concentrations within 15 minutes. Incubation in medium containing 2 mug/mL clarithromycin yielded steady-state intracellular concentrations of 75.8 mug/mL in fibroblasts and 6.6 mug/mL in SCC-25 cells. Clarithromycin transport exhibited Michaelis-Menten kinetics and was inhibited below 37 degrees C. The Michaelis constants for fibro-blasts and SCC-25 cells were 78.4 and 227 mug/mL, respectively, while the maximum transport velocities were 264 and 381 ng/min/10(6) cells, respectively. Thus, both types of cells take up clarithromycin via a concentrative active transport system. By increasing intracellular clarithromycin levels, this system may enhance the effectiveness of clarithromycin against invasive periodontal pathogens.

Timing Affects the Clinical Outcome of Adjunctive Systemic Antibiotic Therapy for Generalized Aggressive Periodontitis

BACKGROUND

Systemic antibiotics improve the outcome of scaling and root planing (SRP) in patients exhibiting severe periodontitis. This study evaluated the influence of timing of adjunctive systemic antibiotics in the sequence of periodontal therapy.

METHODS

Two cohorts of patients with generalized aggressive periodontitis and treated by SRP, adjunctive antibiotics, and supportive periodontal therapy (SPT) were analyzed retrospectively. Cohort A (17 patients; 36 +/- 5 years of age) received systemic amoxicillin/metronidazole immediately after SRP ("immediate"); cohort B (17 patients; 36 +/- 4 years of age) received the same regimen 3 months after SRP, following SPT, including subgingival reinstrumentation ("late"). Clinical parameters, including probing depth (PD), relative attachment level (RAL), bleeding on probing (BOP), and suppuration, were recorded with a pressure-sensitive electronic probe at baseline and 3 and 6 months after SRP.

RESULTS

Significant time*group interactions were found for all clinical parameters except BOP, i.e., timing of antibiotic therapy affected the course of clinical changes over time. Immediate antibiotic therapy produced significantly higher initial changes (0 to 3 months) in PD and RAL. Late antibiotic therapy at 3 months resulted in additional significant improvements in all clinical parameters between 3 and 6 months. In initially deep sites (baseline PD >6 mm), improvements in PD and RAL over 6 months were significantly higher with immediate antibiotic therapy compared to late antibiotic therapy.

CONCLUSION

Within the limits of a retrospective analysis, these findings indicate that administration of amoxicillin/metronidazole immediately after initial SRP provides more PD reduction and RAL "gain" in initially deep sites than late administration at SPT with reinstrumentation after 3 months.

Identification of periodontopathic bacteria in gingival tissue of Japanese periodontitis patients

INTRODUCTION

The identification of invading periodontopathic bacteria in tissues is important to determine their role in the pathogenesis of periodontal disease. The objective of this study was to identify periodontopathic bacteria in diseased gingival tissue of periodontitis patients.

METHODS

Subgingival plaque and gingival tissue were collected from 32 generalized chronic periodontitis (CP), 16 generalized aggressive periodontitis (GAgP) and eight localized aggressive periodontitis (LAgP) patients. Detection frequencies and quantities of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Tannerella forsythensis were investigated by polymerase chain reaction. The prevalences of Streptococcus oralis and Streptococcus sobrinus were also examined and the distribution of A. actinomycetemcomitans serotypes was observed.

RESULTS

P. gingivalis and T. forsythensis were detected in approximately 70% of tissue samples and 50% of plaque samples in the three periodontitis groups. Prevalence of A. actinomycetemcomitans in tissue samples was higher in the LAgP (63%) group than in either the CP (16%) or the GAgP (38%) group. A. actinomycetemcomitans serotype c was detected in 50% of LAgP patients. Detection frequencies of S. oralis and S. sobrinus were markedly low in both plaque and tissue samples from all three periodontitis groups. Amounts of P. gingivalis, A. actinomycetemcomitans and T. forsythensis in the tissue samples were not different among the three periodontitis groups.

CONCLUSION

P. gingivalis, A. actinomycetemcomitans and T. forsythensis can localize in diseased gingival tissue and may be involved in periodontal tissue destruction. Serotype c is the predominant serotype of A. actinomycetemcomitans in Japanese LAgP patients.

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis subgingival presence, species-specific serum immunoglobulin G antibody levels, and periodontitis disease recurrence

BACKGROUND AND OBJECTIVE

The biological and clinical effects of antibody against periodontal pathogenic bacteria are incompletely understood. This study evaluated the inter-relationships among periodontal levels of cultivable Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, species-specific serum immunoglobulin G (IgG) antibody levels, and periodontitis disease activity.

MATERIAL AND METHODS

Forty-three adults who had previously been treated for periodontitis and who also harbored cultivable A. actinomycetemcomitans or P. gingivalis were evaluated semiannually for clinical disease recurrence over a 36-month period. Each patient provided subgingival microbial samples, for the recovery of A. actinomycetemcomitans and P. gingivalis, from the two deepest pockets in each dentition sextant. A. actinomycetemcomitans and P. gingivalis serum IgG antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA), together with whole-cell sonicate extracts from A. actinomycetemcomitans serotypes a-c and P. gingivalis ATCC 33277. Data were analyzed using the Mantel-Haenszel chi-square and Fisher exact two-tailed tests.

RESULTS

Eighteen (60.0%) of 30 A. actinomycetemcomitans-positive subjects, and 10 (76.9%) of 13 P. gingivalis-positive subjects, exhibited recurrent periodontal breakdown within 36 months of periodontal therapy. Nineteen (67.9%) of the 28 patients with active periodontitis had A. actinomycetemcomitans or P. gingivalis serum antibody levels below designated threshold values. In comparison, 10 (66.7%) of 15 culture-positive clinically stable subjects showed A. actinomycetemcomitans or P. gingivalis serum antibody levels above threshold values. The difference between specific antibody levels in periodontitis-active and periodontitis-stable patients was statistically significant (p = 0.032).

CONCLUSIONS

Serum levels of IgG antibodies against A. actinomycetemcomitans or P. gingivalis in periodontitis-stable patients were higher than those in patients with active periodontitis. The results suggest that elevated levels of IgG antibody against A. actinomycetemcomitans and P. gingivalis have a detectable protective effect against periodontal infections with these microorganisms.

Identification of Fur-regulated genes in Actinobacillus actinomycetemcomitans

Actinobacillus actinomycetemcomitans is an oral pathogen that causes aggressive periodontitis as well as sometimes life-threatening, extra-oral infections. Iron regulation is thought to be important in the pathogenesis of A. actinomycetemcomitans infections and, consistent with this hypothesis, the fur gene has recently been identified and characterized in A. actinomycetemcomitans. In this study, 14 putatively Fur-regulated genes were identified by Fur titration assay (Furta) in A. actinomycetemcomitans, including afuA, dgt, eno, hemA, tbpA, recO and yfe – some of which are known to be Fur regulated in other species. A fur mutant A. actinomycetemcomitans strain was created by selecting for manganese resistance in order to study the Fur regulon. Comparisons between the fur gene sequences revealed that nucleotide 66 changed from C in the wild-type to T in the mutant strain, changing leucine to isoleucine. The fur mutant strain expressed a nonfunctional Fur protein as determined by Escherichia coli-based ferric uptake assays and Western blotting. It was also more sensitive to acid stress and expressed higher levels of minC than the wild-type strain. minC, which inhibits cell division in other bacterial species and whose regulation by iron has not been previously described, was found to be Fur regulated in A. actinomycetemcomitans by Furta, by gel shift assays, and by RT-qPCR assays for gene expression.

Modulation of gingival fibroblast minocycline accumulation by biological mediators

Gingival fibroblasts actively accumulate tetracyclines, thereby enhancing their redistribution from blood to gingiva. Since growth factors and pro-inflammatory cytokines regulate many fibroblast activities, they could potentially enhance fibroblast minocycline accumulation. To test this hypothesis, we treated gingival fibroblast monolayers for 1 or 6 hours with platelet-derived growth factor-BB (PDGF), fibroblast growth factor-2 (FGF), transforming growth factor-beta1 (TGF), or tumor necrosis factor-alpha (TNF). Minocycline uptake was assayed at 37 degrees by a fluorescence method. All 4 factors significantly enhanced minocycline uptake (P < or = 0.008, ANOVA), primarily by increasing the affinity of transport. Treatment for 6 hours with 10 ng/mL FGF, PDGF, TGF, or TNF enhanced fibroblast minocycline uptake by 19% to 25%. Phorbol myristate acetate enhanced fibroblast minocycline uptake by 28%, suggesting that protein kinase C plays a role in up-regulating transport. These effects on transport provide a mechanism by which systemic tetracyclines could be preferentially distributed to gingival wound or inflammatory sites.

The gingival crevicular fluid ciprofloxacin level in subjects with gingivitis and periodontitis, and its effects on clinical parameters

OBJECTIVES

The purpose of this study, conducted on patients with gingivitis and periodontitis, was twofold: to find out the serum and gingival crevicular fluid concentration of ciprofloxacin, which is a common drug used effectively against Actinobacillus actinomycetemcomitans and to determine the effects of ciprofloxacin administration on clinical parameters.

METHOD

A total of 32 adult patients, consisting of 16 subjects with gingivitis and 16 subjects with untreated chronic periodontitis, were included in the study. The subjects were divided into four groups: group I included eight subjects with chronic gingivitis who had not previously received any ciprofloxacin; group II included eight subjects with chronic gingivitis to whom three doses of ciprofloxacin were administered (Siprosan 500 mg) to establish adequate gingival crevicular fluid and serum concentrations of the agent; group III consisted of eight subjects with chronic periodontitis who had not received any ciprofloxacin; group IV included eight subjects with chronic periodontitis to whom three doses of ciprofloxacin were administered to establish adequate gingival crevicular fluid and serum concentrations of the agent. All patients were systemically healthy, free of pain and reported no current medication usage. Each patient was treated with scaling and/or root planing using specific hand instruments under local anesthesia. Gingival index, plaque index and clinical attachment levels of the teeth were used to determine the clinical condition of the subjects and findings were recorded at the beginning, seventh day, 21st day and third month of the study. Serum ciprofloxacin level was measured in venous blood. Approximately 5 ml of venous blood was drawn from subjects in groups II and IV using a standard venipuncture technique. Gingival crevicular fluid samples were sampled from six interproximal sites with six paper strips in the posterior region of upper jaw (excluding third molar) and all gingival crevicular fluid and serum samples were evaluated by high-performance liquid chromatography.

RESULTS

The serum concentrations of ciprofloxacin at the first and 72nd hour were not significantly different in subjects with periodontitis compared to subjects with gingivitis. But the gingival crevicular fluid concentrations of ciprofloxacin at the same hours were significantly high in subjects with periodontitis compared to subjects with gingivitis. Both subjects with gingivitis and periodontitis had significantly higher ciprofloxacin levels in the gingival crevicular fluid than in serum. The application of ciprofloxacin did not have any positive or statistically significant effect upon the clinical parameters of the subjects with gingivitis. On the other hand, a significant decrease in the clinical attachment level scores of the subjects with periodontitis (group IV) was observed compared to group III in the 21st day and third month.

CONCLUSION

According to these results, the use of ciprofloxacin as an alternative drug in subjects with periodontitis but not gingivitis can be recommended. However, long-term studies are also needed to assess the effects of ciprofloxacin on clinical parameters.

Distinct transcriptional profiles characterize oral epithelium-microbiota interactions

Transcriptional profiling, bioinformatics, statistical and ontology tools were used to uncover and dissect genes and pathways of human gingival epithelial cells that are modulated upon interaction with the periodontal pathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. Consistent with their biological and clinical differences, the common core transcriptional response of epithelial cells to both organisms was very limited, and organism-specific responses predominated. A large number of differentially regulated genes linked to the P53 apoptotic network were found with both organisms, which was consistent with the pro-apoptotic phenotype observed with A. actinomycetemcomitans and anti-apoptotic phenotype of P. gingivalis. Furthermore, with A. actinomycetemcomitans, the induction of apoptosis did not appear to be Fas- or TNF(alpha)-mediated. Linkage of specific bacterial components to host pathways and networks provided additional insight into the pathogenic process. Comparison of the transcriptional responses of epithelial cells challenged with parental P. gingivalis or with a mutant of P. gingivalis deficient in production of major fimbriae, which are required for optimal invasion, showed major expression differences that reverberated throughout the host cell transcriptome. In contrast, gene ORF859 in A. actinomycetemcomitans, which may play a role in intracellular homeostasis, had a more subtle effect on the transcriptome. These studies help unravel the complex and dynamic interactions between host epithelial cells and endogenous bacteria that can cause opportunistic infections.

Photodynamic therapy for periodontal diseases: State of the art

BACKGROUND

Photodynamic killing of periodontopathogenic bacteria may be an alternative to the systemic application of antibacterial drugs used in the treatment of periodontal diseases. Even though the method is still in the experimental stage, increasing bacterial resistance problems may promote the introduction of photodynamic therapy (PDT) into periodontal practice.

AIM

In this review a literature survey is given of PDT as seen from a periodontal perspective.

METHODS

In this review, the present knowledge and experience of PDT is summarized. Literature data are presented on drawbacks of conventional antibiotics, the mechanism of PDT, bactericidal effects of PDT as well as results of clinical efforts. The future prospects of the method are discussed.

RESULTS

The application of photosensitizing dyes and their excitation by visible light enables effective killing of periodontopathogens. Encouraging studies using PDT in periodontitis and in peri-implantitis are known.

CONCLUSION

Even though PDT is still in experimental stages of development and testing, the method may be an adjunct to conventional antibacterial measures in periodontology. Clinical follow-up studies are needed to confirm the efficacy of the procedure.

Periodontal dressing (VocopacR) influences outcomes in a two-step treatment procedure

OBJECTIVES

It is not clear if periodontal dressing influences the long-term results in a non-surgical treatment procedure.

MATERIAL AND METHODS

The periodontal parameters (pre-baseline) of 36 patients with aggressive periodontitis were obtained before the patients were treated initially (1st step) by a dental hygienist, who completely removed the supra- and subgingival concrements. Baseline parameters were raised 3 weeks after the 1st step, before the 2nd therapy step was conducted. It consisted of a non-surgical procedure, which comprised a closed full-mouth manual root curettage (root planing), immediate systemic application of metronidazole, and the placement of a periodontal dressing (Vocopac, Voco). The patients were randomized to two test groups having their periodontal packs removed after 3-4 days (group 1, n=12) and 7-8 days (group 2, n=12), respectively and a control group (n=12) without periodontal dressing. Clinical parameters were raised again after 6 and 24 months.

RESULTS

Six and 24 months later, changes in probing pocket depth (PPD) and probing attachment level (PAL) were observed in all three groups compared with baseline, but the difference was significant in group 2 only. In addition, group 2 showed a greater reduction in mean PPD and also a significantly greater gain of attachment in comparison with the controls.

CONCLUSION

Wound dressing has a positive effect on clinical long-term results using a two-step non-surgical procedure. Moreover, removing the dressing after 7-8 days leads to clearly better results than removing it earlier.

Distribution of systemic ciprofloxacin and doxycycline to gingiva and gingival crevicular fluid

BACKGROUND

Systemic fluoroquinolones and tetracyclines reach steady-state levels in gingival crevicular fluid (GCF) that are several-fold higher than their levels in serum. The mechanism by which this occurs is unclear, but gingival fibroblasts are known to accumulate these agents. Uptake by fibroblasts could enhance their distribution to gingiva. To test this hypothesis, steady-state levels of these agents were assayed in serum, gingival connective tissue (GCT), and GCF.

METHODS

Healthy subjects who needed resective periodontal surgery participated in the study. Approximately 78 hours prior to the surgical appointment, each subject began a 3-day regimen of ciprofloxacin or doxycycline. At the surgical appointment (scheduled approximately 6 hours after the last dose), samples of blood and GCT were collected. GCF samples were collected on paper strips and measured with an electronic device. Samples were extracted and analyzed by high performance liquid chromatography.

RESULTS

Mean ciprofloxacin levels in serum, GCT, and GCF were 0.40 microg/ml, 1.38 microg/g, and 1.66 microg/ml, respectively (P<0.001, N=9). For doxycycline, these levels were 1.11 microg/ml, 2.03 microg/g, and 2.41 microg/ml, respectively (P=0.002, N=8). For both agents, the GCT and GCF levels were significantly higher than serum levels (P<0.05), but not significantly different from each other.

CONCLUSIONS

Our findings suggest that fibroblasts could play an important role in the distribution of fluoroquinolones and tetracyclines to the gingiva. By accumulating these agents in GCT, fibroblasts could contribute to the relatively high levels they attain in GCF.

The cytolethal distending toxin induces receptor activator of NF-kappaB ligand expression in human gingival fibroblasts and periodontal ligament cells

Actinobacillus actinomycetemcomitans is associated with localized aggressive periodontitis, a disease characterized by rapid loss of the alveolar bone surrounding the teeth. Receptor activator of NF-kappaB Ligand (RANKL) and osteoprotegerin (OPG) are two molecules that regulate osteoclast formation and bone resorption. RANKL induces osteoclast differentiation and activation, whereas OPG blocks this process by acting as a decoy receptor for RANKL. The purpose of this study was to investigate the effect of A. actinomycetemcomitans on the expression of RANKL and OPG in human gingival fibroblasts and periodontal ligament cells. RANKL mRNA expression was induced in both cell types challenged by A. actinomycetemcomitans extract, whereas OPG mRNA expression remained unaffected. Cell surface RANKL protein was also induced by A. actinomycetemcomitans, whereas there was no change in OPG protein secretion. A cytolethal distending toxin (Cdt) gene-knockout strain of A. actinomycetemcomitans did not induce RANKL expression, in contrast to its wild-type strain. Purified Cdt from Haemophilus ducreyi alone, or in combination with extract from the A. actinomycetemcomitans cdt mutant strain, induced RANKL expression. Pretreatment of A. actinomycetemcomitans wild-type extract with Cdt antiserum abolished RANKL expression. In conclusion, A. actinomycetemcomitans induces RANKL expression in periodontal connective tissue cells. Cdt is crucial for this induction and may therefore be involved in the pathological bone resorption during the process of localized aggressive periodontitis.

Serum and gingival crevicular fluid levels of ciprofloxacin in patients with periodontitis

BACKGROUND

The use of antibiotics as an adjunctive therapy in the treatment of periodontal diseases is of special interest to dental practitioners. In addition to using an appropriate antibacterial agent, clinicians may find it useful to determine the local and systemic concentrations of antibiotics in infected periodontal sites to reduce the levels of bacteria. The purpose of this study was to determine the serum and gingival crevicular fluid, or GCF, concentrations of systemic ciprofloxacin in patients with periodontitis.

METHODS

Ten subjects with chronic periodontitis received ciprofloxacin (500 milligrams) twice daily for five days. The authors collected GCF and serum samples immediately after administering the first dose (baseline = 0 hours) and at consecutive time points. The orifice method was used for GCF sampling, and 5 milliliters of venous blood was drawn for serum analysis. The authors used high-performance liquid chromatography to determine ciprofloxacin concentrations in GCF and serum.

RESULTS

The authors found that ciprofloxacin concentrations in GCF were significantly higher than concentrations in serum at two, four, seven, 24 and 120 hours. Ciprofloxacin reached the maximum concentration, or Cmax (3.72 micrograms/ mL), in GCF two hours after the initial dose was administered. The concentration decreased to 2.06 microg/mL 24 hours after the initial administration of the drug. Serum Cmax was 2.58 microg/mL at 1.5 hours, and the concentration decreased to 0.26 microg/mL at 24 hours.

CONCLUSION

The results of this clinical study show that ciprofloxacin is found in GCF and its concentration in GCF is significantly higher than that in serum.

CLINICAL IMPLICATIONS

Ciprofloxacin may be useful in treating patients with periodontitis because it reaches higher concentrations in GCF than in serum.

Cell cycle arrest of human gingival fibroblasts and periodontal ligament cells byActinobacillus actinomycetemcomitans: involvement of the cytolethal distending toxin

The cytolethal distending toxin (Cdt) is produced by several Gram-negative bacterial species and causes growth arrest and morphological alterations in mammalian cells. Actinobacillus actinomycetemcomitans, which is involved in the pathogenesis of localized aggressive periodontitis, also produces a Cdt that affects periodontal connective tissue cells. The aim of this study was to investigate in which phase of the cell cycle these cells are arrested and enlarged when challenged with A. actinomycetemcomitans, and to evaluate the involvement of its Cdt. Human gingival fibroblasts and periodontal ligament cells were challenged with A. actinomycetemcomitans extract, or with purified Cdt, and cell cycle analysis was performed by propidium iodide staining and flow cytometry. Cells exposed to an A. actinomycetemcomitans wild-type strain, or to purified Cdt, were arrested in both G1 and G2/M phases, and appeared enlarged compared to the corresponding controls. The cellular enlargement occurred in both G1 and G2/M arrested cells. In contrast, cells exposed to an A. actinomycetemcomitans cdt-knockout mutant strain showed cell cycle phase distribution and size similar to the controls. In conclusion, A. actinomycetemcomitans causes a combined G1 and G2/M growth arrest and enlargement in periodontal connective tissue cells, which is attributed to its Cdt.