Microbial etiological agents of destructive periodontal diseases

Phototargeting oral black-pigmented bacteria

We have found that broadband light (380 to 520 nm) rapidly and selectively kills oral black-pigmented bacteria (BPB) in pure cultures and in dental plaque samples obtained from human subjects with chronic periodontitis. We hypothesize that this killing effect is a result of light excitation of their endogenous porphyrins. Cultures of Prevotella intermedia and P. nigrescens were killed by 4.2 J/cm2, whereas P. melaninogenica required 21 J/cm2. Exposure to light with a fluence of 42 J/cm2 produced 99% killing of P. gingivalis. High-performance liquid chromatography demonstrated the presence of various amounts of different porphyrin molecules in BPB. The amounts of endogenous porphyrin in BPB were 267 (P. intermedia), 47 (P. nigrescens), 41 (P. melaninogenica), and 2.2 (P. gingivalis) ng/mg. Analysis of bacteria in dental plaque samples by DNA-DNA hybridization for 40 taxa before and after phototherapy showed that the growth of the four BPB was decreased by 2 and 3 times after irradiation at energy fluences of 4.2 and 21 J/cm2, respectively, whereas the growth of the remaining 36 microorganisms was decreased by 1.5 times at both energy fluences. The present study suggests that intraoral light exposure may be used to control BPB growth and possibly benefit patients with periodontal disease.

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.

The Trans-Chromosomic Mouse-Derived Human Monoclonal Antibody Promotes Phagocytosis ofPorphyromonas gingivalisby Neutrophils

BACKGROUND

As a safe immunotherapeutic approach, human monoclonal antibody (hMAb) may be effective in clearing periodontopathic bacteria. The trans-chromosomic (TC) technology has recently been applied to construction of the TC mouse, which enables us to incorporate entire human chromosome fragments containing immunoglobulin (Ig) gene cluster. The aim of this study is to establish TC mouse-derived hMAb, and to test the in vitro opsonophagocytic activity.

METHODS

Human Ig-producing TC mouse was immunized by recombinant 40-kDa outer membrane protein (r40-kDa OMP) of Porphyromonas gingivalis 381, and the spleen cells were fused with the mouse myeloma cell line. The specificity of antir40- kDa OMP hMAb was evaluated with the enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance assays. Flow cytometric analyses were performed to assess the opsonophagocytic activity.

RESULTS

We successfully constructed 99 IgG isotype clones (IgG1: 84; IgG2: 11; IgG4: four clones), which were specifically reactive with r40-kDa OMP. The anti-r40-kDa OMP IgG1 hMAbs promoted phagocytosis of P. gingivalis by neutrophils. Futhermore, an increased opsonophagocytic activitity of anti-r40-kDa OMP IgG1 hMAbs was observed not only in P. gingivalis 381, but also in the W50, W83, and Su63 strains.

CONCLUSION

Our results document the TC mouse-derived hMAb to promote neutrophil phagocytosis of P. gingivalis, suggesting an immunotherapeutic option for clearance of P. gingivalis.

Experimental gingivitis in type 1 diabetics: a controlled clinical and microbiological study

OBJECTIVE

To monitor clinical and microbiological changes during experimental gingivitis in type 1 diabetics and non-diabetics.

MATERIALS AND METHODS

Nine type 1 diabetics with good/moderate metabolic control and nine age-gender matched non-diabetics were recruited. Probing pocket depths in all subjects did not exceed 4 mm and none were affected by attachment loss. According to the original model, an experimental 3-week plaque accumulation resulting in experimental gingivitis development and a subsequent 2-week period of optimal plaque control were staged. Subgingival plaque samples were collected at days 0, 21 and 35 from one site per quadrant, pooled and analysed using checkerboard DNA-DNA hybridization.

RESULTS

Diabetics (mean age 25.6+/-5.8 standard deviation (SD), range 16-35 years) had a mean HbA1c level of 8.1+/-0.7% (SD), while non-diabetics (mean age 24.8+/-5.7 (SD), range 15-36 years) were metabolically controlled (HbA1c< or =6.5%). Between Days 0, 21 and 35, no statistically significant differences in mean plaque and gingival index scores were observed between diabetics and non-diabetics. At days 7 and 21, however, diabetics showed statistically significantly higher percentages of sites with gingival index scores > or =2 compared with non-diabetics. Mean DNA probe counts of the red and orange complex species increased significantly (p<0.05) between days 0 and 21 and decreased significantly (p<0.05) between days 21 and 35 in both groups.

CONCLUSION

Both diabetics and non-diabetics react to experimental plaque accumulation with gingival inflammation. Type 1 diabetics, however, develop an earlier and higher inflammatory response to a comparable bacterial challenge.

Porphyromonas gingivalis bacteremia induces coronary and aortic atherosclerosis in normocholesterolemic and hypercholesterolemic pigs

OBJECTIVES

The aim of this study was to determine whether recurrent intravenous injections with Porphyromonas gingivalis (P gingivalis), mimicking periodontitis-associated bacteremia, promotes coronary artery and aortic atherosclerosis in pigs.

METHODS AND RESULTS

Pigs (n=36) fed low- or high-fat chow were divided into P gingivalis-sensitized and P gingivalis-challenged groups or P gingivalis-sensitized controls and saline-treated controls. Pigs were sensitized with 10(9) killed P gingivalis subcutaneously. Four weeks later all sensitized pigs in the group to be challenged started intravenous injections thrice weekly for 5 months with 10(6) to 10(7) colony forming units of P gingivalis while controls received saline. Anti-P gingivalis antibody, serum cholesterol, and complete blood counts were assayed monthly. Pigs were euthanized 2 weeks after the last injection, and coronary arteries and aortas were analyzed by histomorphometry and immunohistochemistry. Anti-P gingivalis antibody was increased by P gingivalis exposure. P gingivalis-challenged pigs developed a significantly greater amount of coronary and aortic atherosclerosis than controls in the normocholesterolemic group and nearly significant in the hypercholesterolemic group. P gingivalis was detected by polymerase chain reaction in arteries from most (94%, 16 of 17) P gingivalis-challenged pigs but not controls.

CONCLUSIONS

Recurrent P gingivalis bacteremia induces aortic and coronary lesions consistent with atherosclerosis in normocholesterolemic pigs and increases aortic and coronary atherosclerosis in hypercholesterolemic pigs.

The prevalence and pathogenic differences of Porphyromonas gingivalis fimA genotypes in patients with aggressive periodontitis

BACKGROUND

The fimA gene, which encodes fimbrillin (FimA), is found in Porphyromonas gingivalis and has been classified into six genotypes based on nucleotide sequence. P. gingivalis that possesses the type II fimA gene is prevalent in adult periodontitis.

OBJECTIVES

The aim of this study was to investigate the prevalence of P. gingivalis fimA genotypes in Japanese aggressive periodontitis patients, and to examine their virulence.

METHODS

Subgingival plaque samples were obtained from 223 sites in 18 aggressive periodontitis patients and 95 sites in 22 periodontally healthy young adults. Actinobacillus actinomycetemcomitans, P. gingivalis and Tannerella forsythensis detection, determination of the fimA genotype in P. gingivalis, and the quantification of P. gingivalis were analyzed by polymerase chain reaction (PCR) methods. The proteolytic activities of the P. gingivalis fimA type I and fimA type II were also examined.

RESULTS

In aggressive periodontitis patients, the most prevalent fimA genotype was the type II (46.7%), followed by the type Ib and type I, whereas in healthy subjects, the type I fimA was the only genotype detected. The number of P. gingivalis pathogens was the greatest in the type I fimA positive sites, and the frequency of coexisting A. actinomycetemcomitans and T. forsythensis was highest in the type II fimA positive sites in the aggressive periodontitis patients. Both the arginine-specific cysteine proteinase (Arg-gingipain) and lysine-specific cysteine proteinase (Lys-gingipain) activity of the P. gingivalis fimA type I strain were significantly higher than those of the fimA type II strains.

CONCLUSIONS

These results suggest that differences in virulence exist among different fimA genotypes. Coadherence with other pathogens in P. gingivalis fimA type II-associated aggressive periodontitis and quantitative increases in P. gingivalis in fimA type I-associated aggressive periodontitis are related to this virulence.

Scaling and root planing, systemic metronidazole and professional plaque removal in the treatment of chronic periodontitis in a Brazilian population II - microbiological results

OBJECTIVE

The current investigation evaluated changes in levels and proportions of 39 bacterial species in subgingival plaque samples after scaling and root planing (SRP) alone or in combination with systemic metronidazole and/or professional cleaning in subjects with chronic periodontitis.

METHODS

Forty-four adult subjects (mean age 45+/-6 years) with periodontitis were randomly assigned in four treatment groups, a control (C, n=10) that received SRP and placebo and three test groups treated as follows: T1 (n=12): SRP and metronidazole (M, 400 mg tid) for 10 days; T2 (n=12): SRP, weekly professional supragingival plaque removal for 3 months (PC) and placebo; and T3 (n=10): SRP, M and PC. Subgingival plaque samples were taken from seven sites per subject at baseline and 90 days post-therapy. Counts of 39 subgingival species were determined using checkerboard DNA-DNA hybridization. Significance of differences over time was determined using the Wilcoxon signed ranks test and among groups using ancova.

RESULTS

The mean counts of the majority of the species were reduced post-therapy in the 4 treatment groups. Counts (x 10(5)+/-SEM) of Porphyromonas gingivalis, Tannerella forsythensis and Treponema denticola were significantly reduced in groups T2 and T3. Levels of beneficial species, such as some Actinomyces species, Veillonella parvula, Streptococcus sanguis, Streptococcus oralis and Streptococcus gordonii were minimally affected in levels when the combined therapy was applied (T3). Mean proportions of red complex species decreased from 18.4% at baseline to 3% at 90 days post-therapy in group T3 (p<0.01), from 25.8% to 2.3% in group T2 (p<0.01), from 17.7% to 5.6% in group T1 (p<0.05) and from 19.4% to 8.8% in group C (NS). Proportions of the suspected periodontal pathogens from the orange complex were also markedly reduced in groups T2 and T3.

CONCLUSIONS

All treatments reduced counts and proportions of red complex species. Adjunctive therapy appeared to have a greater effect and also affected members of the orange complex.

Levels of interleukin-17 in gingival crevicular fluid and in supernatants of cellular cultures of gingival tissue from patients with chronic periodontitis

BACKGROUND AND AIMS

Interleukin-17 (IL-17) is a T-cell-derived cytokine that may play an important role in the initiation or maintenance of the pro-inflammatory response and has recently been found to stimulate osteoclastic resorption. The purpose of the present study was to determine the presence of IL-17 in gingival crevicular fluid (GCF) samples and in the culture supernatants of gingival cells from patients with chronic periodontitis.

METHOD

GCF samples were collected during 30 s from two sites in 16 patients from periodontally affected sites (probing depth > or =5 mm, attachment loss > or =3 mm). The comparison with healthy controls was carried out by collecting GCF samples from eight healthy volunteers. GCF was collected using a paper strip and ELISA was performed to determine the total amount of IL-17. Supernatant cellular cultures of gingival cells were obtained from periodontal biopsies taken from 12 periodontitis patients and from eight healthy control subjects during the surgical removal of wisdom teeth. Spontaneous and phytohaemagglutinin (PHA)-stimulated levels of IL-17 were determined by ELISA.

RESULTS

The total amount of cytokine IL-17 was significantly higher in the periodontitis group than the control group (45.9 versus 35.6 pg, p=0.005). Significantly higher GCF volume and amount of total proteins were obtained from periodontitis patients as compared with control subjects (0.98 versus 0.36 microl, p=0.0005; 0.12 versus 0.05 microg, p=0.0005, respectively). A higher concentration of IL-17 was detected in culture supernatants from periodontitis patients compared with healthy subjects, either without stimulation (36.28+/-8.39 versus 28.81+/-1.50 microg/ml, p=0.011) or with PHA stimulation (52.12+/-14.56 versus 39.00+/-4.90 microg/ml, p=0.012). Treatment with PHA induced a significant increase in the production of IL-17 in healthy subjects and periodontitis patients (p=0.001 and 0.003).

CONCLUSIONS

The total amount of cytokine IL-17 in GCF samples and in the culture supernatants of gingival cells are significantly increased in periodontal disease.

Iron and heme utilization in Porphyromonas gingivalis

Porphyromonas gingivalis is a Gram-negative anaerobic bacterium associated with the initiation and progression of adult periodontal disease. Iron is utilized by this pathogen in the form of heme and has been shown to play an essential role in its growth and virulence. Recently, considerable attention has been given to the characterization of various secreted and surface-associated proteins of P. gingivalis and their contribution to virulence. In particular, the properties of proteins involved in the uptake of iron and heme have been extensively studied. Unlike other Gram-negative bacteria, P. gingivalis does not produce siderophores. Instead it employs specific outer membrane receptors, proteases (particularly gingipains), and lipoproteins to acquire iron/heme. In this review, we will focus on the diverse mechanisms of iron and heme acquisition in P. gingivalis. Specific proteins involved in iron and heme capture will be described. In addition, we will discuss new genes for iron/heme utilization identified by nucleotide sequencing of the P. gingivalis W83 genome. Putative iron- and heme-responsive gene regulation in P. gingivalis will be discussed. We will also examine the significance of heme/hemoglobin acquisition for the virulence of this pathogen.

Modulation of cytokine production by Porphyromonas gingivalis in a macrophage and epithelial cell co-culture model

Epithelial cells and macrophages play a major role in the host response to Porphyromonas gingivalis, a major etiologic agent of chronic periodontitis. Secretion of high levels of cytokines by these cells is believed to contribute to periodontal tissue destruction. To investigate the interactions between P. gingivalis and these two major cell types, we characterized the production of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-alpha) and regulated on activation normal T cell expressed and secreted (RANTES) by an in vitro co-culture model composed of epithelial-like transformed cells (HeLa cell line) and macrophage-like cells (phorbol myristic acid-differentiated U937 cell line) following a challenge with different strains of P. gingivalis. P. gingivalis cells stimulated the secretion of pro-inflammatory cytokines (IL-1beta and IL-6) and chemokines (IL-8 and RANTES) in the co-culture model. Responses to P. gingivalis infection were influenced by the macrophage/epithelial cell ratios of the cultures. In addition, the level of secretion of these inflammatory mediators was dependent on the bacterial strain and the multiplicity of infection (MOI) used. The use of a gingipain-deficient mutant of P. gingivalis or the addition of a cysteine protease inhibitor suggested that the level of cytokines secreted by the co-culture model was underestimated due to an extensive proteolytic degradation. This study showed that P. gingivalis can modulate the levels of inflammatory mediators, which may contribute to the progression of periodontitis.

Systemic antibiotics in periodontics

This position paper addresses the role of systemic antibiotics in the treatment of periodontal disease. Topical antibiotic therapy is not discussed here. The paper was prepared by the Research, Science and Therapy Committee of the American Academy of Periodontology. The document consists of three sections: 1) concept of antibiotic periodontal therapy; 2) efficacy of antibiotic periodontal therapy; and 3) practical aspects of antibiotic periodontal therapy. The conclusions drawn in this paper represent the position of the American Academy of Periodontology and are intended for the information of the dental profession.

Introns in the cytolethal distending toxin gene of Actinobacillus actinomycetemcomitans

In eukaryotic cells, genes are interrupted by intervening sequences called introns. Introns are transcribed as part of a precursor RNA that is subsequently removed by splicing, giving rise to mature mRNA. However, introns are rarely found in bacteria. Actinobacillus actinomycetemcomitans is a periodontal pathogen implicated in aggressive forms of periodontal disease. This organism has been shown to produce cytolethal distending toxin (CDT), which causes sensitive eukaryotic cells to become irreversibly blocked at the G2/M phase of the cell cycle. In this study, we report the presence of introns within the cdt gene of A. actinomycetemcomitans. By use of reverse transcription-PCR, cdt transcripts of 2.123, 1.572, and 0.882 kb (RTA1, RTA2, and RTA3, respectively) were detected. In contrast, a single 2.123-kb amplicon was obtained by PCR with the genomic DNA. Similar results were obtained when a plasmid carrying cdt was cloned into Escherichia coli. Sequence analysis of RTA1, RTA2, and RTA3 revealed that RTA1 had undergone splicing, giving rise to RTA2 and RTA3. Two exon-intron boundaries, or splice sites, were identified at positions 863 to 868 and 1553 to 1558 of RTA1. Site-directed and deletion mutation studies of the splice site sequence indicated that sequence conservation was important in order for accurate splicing to occur. The catalytic region of the cdt RNA was located within the cdtC gene. This 0.56-kb RNA behaved independently as a catalytically active RNA molecule (a ribozyme) in vitro, capable of splicing heterologous RNA in both cis and trans configurations.

Prevalence of Periodontopathic Bacteria in Aggressive Periodontitis Patients in a Chilean Population

BACKGROUND

Actinobacillus actinomycetemcomitans is considered a major etiologic agent of aggressive periodontitis (AgP). Other periodontopathic bacteria such as Porphyromonas gingivalis are also suspected of participating in aggressive periodontitis although the evidence to support this is controversial. The aim of the present study was to determine the prevalence of eight periodontopathic bacteria in Chilean patients with AgP.

METHODS

Subgingival plaque samples were collected from 36 aggressive, 30 localized, and six generalized periodontitis patients. Samples from 17 advanced chronic periodontitis (CP) patients were taken as controls. Samples collected from the four deepest periodontal pockets in each patient were pooled in prereduced transport fluid (RTF) and cultured. Periodontal bacteria were primarily identified by colony morphology under stereoscopic microscope and rapid biochemical tests. The identity of some bacterial isolates was confirmed by colony polymerase chain reaction (PCR).

RESULTS

AgP showed a significatively higher prevalence of C. rectus than CP (P = 0.036). The only statistical difference found was for C. rectus. Patients with AgP showed a higher, but not statistically significant, prevalence of P. gingivalis, E. corrodens, P. micros, and Capnocytophaga sp. A similar prevalence in both groups of patients was observed for F. nucleatum and P. intermedia/nigrescens, and A. actinomycetemcomitans was less prevalent in AgP than CP patients. In localized AgP, P. intermedia/nigrescens, E. corrodens, F. nucleatum, and P. micros were the more prevalent pathogens in contrast to generalized AgP patients who harbored A. actinomycetemcomitans, P. gingivalis, and Capnocytophaga sp. as the most prevalent bacteria.

CONCLUSIONS

C. rectus, P. gingivalis, E. corrodens, P. micros, and Capnocytophaga sp. were the most predominant periodontopathic bacteria of AgP in this Chilean population, but the only statistical difference found here between AgP and CP was for C. rectus, suggesting that the differences in clinical appearance may be caused by factors other than the microbiological composition of the subgingival plaque of these patients. In this study, the prevalence of A. actinomycetemcomitans was much lower than that of P. gingivalis.

The effect of HAART on salivary microbiota in the Women's Interagency HIV Study (WIHS)

OBJECTIVE

Study the prevalence of potentially pathogenic microorganisms in saliva of HIV-positive women in the Women's Interagency HIV Study.

STUDY DESIGN

157 HIV-positive and 31 HIV-negative women were studied. At baseline and every 6 months over 4 years, information was collected on socioeconomic and educational status, oral and systemic health, including HIV markers and antiretroviral therapy, and frequency of professional oral care utilization. Bacterial and yeast pathogenic isolates from stimulated whole saliva were tentatively identified using standard methodologies.

RESULTS

The prevalence of microorganisms in stimulated saliva of HIV-positive women was not significantly different from that of HIV-negative women. In HIV-positive women, highly active antiretroviral therapy (HAART) was independently and significantly associated with the presence of a variety of salivary bacterial species. HAART increased the risk for recovering Fusobacterium species (P < .001), enteric gram-negative rods (P < .05), Peptostreptococcus micros (P < .05), Campylobacter species (P < .0001), Eubacterium species (P < .001), and Tannerella forsythia (P < .01). In contrast, HAART led to decreased recovery rate of yeasts (Candida albicans and Candida dubliniensis) (P < .0001).

CONCLUSION

The present findings suggest that the institution of HAART promotes an increasingly pathogenic salivary microbiota, at least temporarily. Similar findings have been reported for various nonoral microbial ecosystems.

Non-Surgical Periodontal Therapy With Adjunctive Topical Doxycycline: A Double-Masked, Randomized, Controlled Multicenter Study. II. Microbiological Results

BACKGROUND

Topical application of active substances offers an additional option in periodontal therapy. The aim of this study was to examine the influence of the administration of a novel, biodegradable 14% doxycycline gel on microbiological findings, in connection with scaling and root planing.

METHODS

One hundred ten patients in three centers (Frankfurt and Heidelberg, Germany; Nijmegen, The Netherlands) with moderate to advanced periodontitis were evaluated in this randomized, double-masked, split-mouth clinical trial. In each patient, three test teeth were randomly assigned to one of three treatment modalities: 1) scaling and root planing (SRP) alone; 2) SRP with subgingival placebo gel (VEH); or 3) SRP and 14% doxycycline gel (DOX). Subgingival plaque samples were analyzed at baseline and 3 and 6 months after therapy for Actinobacillus actinomycetemcomitans (A.a.), Tannerella forsythensis (T.f.), Porphyromonas gingivalis (P.g.), and Treponema denticola (T.d.) using a RNA probe. Samples from 10 patients were tested for resistance against doxycycline, amoxicillin/clavulanic acid, cefoxitin, clindamycin, and metronidazole using agar diffusion testing.

RESULTS

The largest decrease in pathogens was found after 3 months, with the most pronounced differences between DOX and SRP (P <0.05). At 6 months, pathogens were still reduced markedly in all groups. Treatment results were consolidated for VEH and DOX, with a slight deterioration for SRP (DOX versus SRP: P <0.001). Resistance was observed to amoxycillin/clavulanic acid, cefoxitin, clindamycin, and metronidazole (four isolates) but not to doxycycline.

CONCLUSION

The addition of subgingival instillation of a 14% doxycycline gel resulted in pronounced reduction of periodontal pathogens after 3 months and stabilizing results up to 6 months after therapy. Resistance to doxycycline was not induced.

Micromonas (Peptostreptococcus) micros: unusual case of prosthetic joint infection associated with dental procedures

Micromonas (Peptostreptococcus) micros is frequently associated with periodontal disease as well as respiratory, gastrointestinal and female genitourinary tract infections, but only rarely has been reported as a pathogenic agent of prosthetic joint infections. Here we describe a case of a 63-year-old woman with prosthetic joint infection of total hip arthroplasty caused by the anaerobic species Micromonas micros, associated with tooth extraction. Samples obtained intraoperatively and from the oral cavity were positive for the presence of M. micros by culture and by real-time PCR. This case report indicates that infections of prosthetic joints can be associated with dental procedures and that sensitive molecular techniques are necessary for their routine diagnostic.

Gene expression profiling and characterization under hemin limitation in Porphyromonas gingivalis

Hemin is an important nutrient for Porphyromonas gingivalis growth and pathogenicity. We examined the gene expression profile of P. gingivalis, including genes involved in its pathogenicity, at various growth stages under hemin-standard and limited conditions by using a custom-made microarray. The transcription of many genes decreased after late-log and mid-log phases under hemin-standard and limited conditions, respectively. We focused on two groups of genes while comparing gene expression profiles under hemin-standard and limited conditions by gene tree analysis. Genes belonging to group A maintained high transcriptional levels, whereas genes in group B were expressed at low levels under standard hemin conditions. However, group B genes increased remarkably under hemin-limited conditions. Groups A and B contained genes involved in regulatory functions and protein fate, respectively. Genes related to energy metabolism, transport, and protein binding were present in both groups. Our results suggest that P. gingivalis experienced severe stress under hemin-limited conditions, and growth phase-dependent changes in transcription levels were observed for many genes. Moreover, increased expression of genes involved in energy metabolism suggests that hemin is related not only to pathogenicity, but also energy metabolism.

Prevalence of periodontal pathogens in dental plaque of children

Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, and Tannerella forsythensis have been implicated as the main etiological agents of periodontal disease. The purpose of this work was to estimate the prevalence of these organisms in plaque from children without gingivitis (group 1; n = 65) and from those with gingivitis (group 2; n = 53). Extracted DNA from plaque was subjected to two rounds of PCR targeting the 16S rRNA gene using both universal primers and species-specific primers. The results were as follows: group 1, P. gingivalis, 49%; A. actinomycetemcomitans, 55%; and T. forsythensis, 65%; group 2, P. gingivalis, 47%; A. actinomycetemcomitans, 59%; and T. forsythensis, 45%. T. forsythensis was detected more frequently in children with no gingivitis than in those with gingivitis (P = 0.03). There was no significant difference between the two groups with respect to the presence of P. gingivalis or A. actinomycetemcomitans in either group (P > 0.05). Logistic regression analysis revealed that the odds of a patient having gingivitis were 2.3 times greater in the absence of T. forsythensis. In conclusion, the results of this study have shown that the three pathogens can be detected in the dental plaque of healthy children and of those with gingivitis and that T. forsythensis is associated with dental plaque at sites with no gingivitis.

Actinobacillus actinomycetemcomitansLipopolysaccharide Activates Matrix Metalloproteinase-2 and Increases Receptor Activator of Nuclear Factor-κB Ligand Expression in Human Periodontal Ligament Cells

BACKGROUND

The lipopolysaccharide (LPS) of A. actinomycetemcomitans is one of the major pathogenic factors in periodontal disease. It induces secretion of proinflammatory cytokines and is involved in alveolar bone destruction. We hypothesized that the LPS of A. actinomycetemcomitans could affect the activation of matrix metalloproteinase (MMP)-2 and the expression of receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin in human periodontal ligament (HPDL) cells leading to the destruction of periodontium.

METHODS

HPDL cells were cultured in serum-free medium with or without the LPS of A. actinomycetemcomitans for 36 hours. The activation of MMP-2 was analyzed by zymography. Changes of the expression of RANKL and osteoprotegerin (OPG) were examined by reverse transcription-polymerase chain reaction and supported by Western blot analysis.

RESULTS

The activation of MMP-2 could be induced by the LPS of A. actinomycetemcomitans in HPDL cells and could be inhibited by a serine protease inhibitor. This result suggested that the LPS might activate MMP-2 through a serine protease-dependent pathway. This activation was also blocked by NF-kappaB inhibitor, which indicated the involvement of NF-kappaB. The upregulation of RANKL but not OPG by the LPS was found in both transcription and translation and could be reduced by indomethacin. In addition, serine protease inhibitor also inhibited the upregulation of RANKL, suggesting the activity of serine protease.

CONCLUSIONS

The effect of the LPS of A. actinomycetemcomitans on HPDL cells is serum-independent and the induction of the activation of MMP-2 and the expression of RANKL are serine protease-dependent pathways. The results suggest the role of HPDL cells in the pathogenesis of periodontitis.

In vitro studies on controlled-release cellulose acetate films for local delivery of chlorhexidine, indomethacin, and meloxicam

BACKGROUND

Delivery of medications into periodontal pockets to suppress or eradicate the pathogenic microbiota or modulate the inflammatory response, thereby limiting periodontal tissue destruction, has attracted significant interest with the purpose of effective periodontal treatment. However, no study has previously attempted to develop a controlled-release formulation of anti-inflammatory agents to be used in the field of periodontology. The aim of the present study was to examine the in vitro release profile of chlorhexidine gluconate, indomethacin, and meloxicam from cellulose acetate films.

METHODS

Cellulose acetate films containing chlorhexidine gluconate, indomethacin, and meloxicam were prepared and cut in a form to fit to the periodontal pocket anatomy. The release of active agents was studied in 10 ml artificial saliva at 37 degrees C. Apparatus Vibrax was used at 150 r.p.m. Determinations were carried out spectrophotometrically and the release profiles were plotted as a function of time.

RESULTS

The formulations showed two different release patterns for a total observation period of approximately 120 h. When the formulations of the three active agents were compared, the release patterns of meloxicam and chlorhexidine gluconate were found to be similar, while the indomethacin-containing formulation exhibited the fastest release rate.

CONCLUSIONS

As a conclusion, cellulose acetate may be a suitable inert material for obtaining a prolonged local release of various anti-inflammatory agents like meloxicam. Further in vitro and in vivo studies are required before starting clinical applications of these controlled-release formulations of anti-inflammatory agents.

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.

MMP-2 activation byActinobacillus actinomycetemcomitanssupernatant in human PDL cells was corresponded with reduction of TIMP-2

OBJECTIVE

Matrix metalloproteinase 2 (MMP-2) has been implicated to play a role in pathogenesis of periodontal disease. We recently reported that Porphyromonas gingivalis supernatant could activate MMP-2 in human periodontal ligament (HPDL) cells. In this study, activation of MMP-2 by Actinobacillus actinomycetemcomitans supernatant and the mechanism was investigated.

METHODS

HPDL cells were treated with either A. actinomycetemcomitans or P. gingivalis supernatant for 48 h. To verify the mechanism, pretreated inhibitors were used. Gelatin zymography, RT-PCR and Western blot analysis were used to detect the activation of MMP-2, expression of MT1-MMP and TIMP-2 mRNA and the proteins, respectively.

RESULTS

The supernatant from A. actinomycetemcomitans could activate MMP-2 in HPDL cells similar to that from P. gingivalis but by a different mechanism. Activation by A. actinomycetemcomitans supernatant was correlated with a reduction of TIMP-2 secretion without any alteration of MT1-MMP, while activation by P. gingivalis increased MT1-MMP but no change of TIMP-2 was found.

CONCLUSION

The supernatant from A. actinomycetemcomitans and P. gingivalis could induce the activation of MMP-2 possibly through the imbalance of MT1-MMP and TIMP-2 in HPDL cells but by different mechanisms. The imbalance of MT1-MMP and TIMP-2 may be another factor that is involved in the severity of periodontal disease.

Clinical and microbiological effects of topical subgingival application of hyaluronic acid gel adjunctive to scaling and root planing in the treatment of chronic periodontitis

BACKGROUND

Hyaluronic acid (HA) has shown anti-inflammatory effects in gingivitis therapy. The potential benefits of local subgingival application of HA adjunctive to scaling and root planing (SRP) were evaluated in this study.

METHODS

Twenty patients with chronic periodontitis were included in this split-mouth study. Sulcus fluid flow rate (SFFR) and sulcus bleeding index were monitored at baseline and after 1, 2, 3, 4, 5, 6, and 12 weeks; probing depth and clinical attachment level were monitored at baseline and 6 and 12 weeks. Subgingival plaque samples were also taken at these same three appointments to determine the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola. All patients were treated with full-mouth scaling and root planing (SRP); in addition, an HA gel was administered subgingivally in the test sites every week for 6 weeks.

RESULTS

An improvement of all clinical variables was observed (P < 0.05) in both groups. Clinically, no difference between test and control sites could be found. No difference between test and control sites was seen in the tested microorganisms.

CONCLUSIONS

No clinical or microbiological improvement was achieved by the adjunctive use of HA gel compared to SRP alone. Only SFFR was affected by the use of HA in terms of a more rapid reduction of SFFR in the test sites.

Occurrence of Porphyromonas gingivalis and Tannerella forsythensis in periodontally diseased and healthy subjects

BACKGROUND

The purpose of this study was to compare the prevalence and level of Porphyromonas gingivalis (P. gingivalis) and Tannerella forsythensis (T. forsythensis) in subgingival plaque samples from both healthy individuals and periodontal patients in different age groups.

METHODS

A total of 498 subgingival plaque samples were studied. These samples were collected from 407 individuals diagnosed with periodontal disease (210 adult periodontitis [AP], 78 rapidly progressive periodontitis [RPP], and 119 refractory periodontitis [Ref-P] cases) and 91 healthy (H) subjects. P. gingivalis and T. forsythensis were detected by indirect immunofluorescent assay using species-specific polyclonal antisera to P. gingivalis strain (FDC 381) and T. forsythensis strain (FDC 335). The prevalence of P. gingivalis and T. forsythensis was compared by chi-square analysis. Differences in P. gingivalis and T. forsythensis levels among various periodontal status and age groups was determined by one-way analysis of variance and Fisher's multiple comparison tests. The association between the presence of P. gingivalis or T. forsythensis in different periodontal status and age groups was measured using odds ratios.

RESULTS

P. gingivalis was found in 85.7% (P < 0.0001) and T. forsythensis in 60.7% (P = 0.0002) of diseased subjects compared to 23.1% and 39.6%, respectively, in healthy subjects. P. gingivalis, but not T. forsythensis, was detected more frequently in any diseased group than in the H group in every age group (P<0.0001). No significant difference was found in the prevalence of P. gingivalis and T. forsythensis among age groups, except T. forsythensis was more prevalent in the age group of 40 to 59 years than in the age group < 20 years (chi2 = 3.93, P = 0.047) in the H group. The mean level of P. gingivalis and T. forsythensis was significantly higher in diseased groups than in the H group (P < 0.0001). The odds ratio for P. gingivalis in the AP group (25.0) was greater than any other group for P. gingivalis or T. forsythensis compared to the H group.

CONCLUSIONS

These data suggested that P. gingivalis is closely associated with the pathogenesis of periodontitis and that it may not be a normal inhabitant of periodontally healthy subjects. T. forsythensis is also important in the pathogenesis of periodontal disease; however, whether it causes periodontal disease or is a secondary invader of periodontal lesions remains to be determined.

CARD15 gene mutations in periodontitis

OBJECTIVES

The CARD15 gene encodes the Nod2 protein, which is involved in intracellular recognition of bacterial products like peptidoglycan, activates inflammation and regulates apoptosis through nuclear factor-kappa B, a transcription factor that plays a central role in the innate immunity. Two functional mutations, an insertion mutation at nucleotide 3020 (3020insC) and a missense mutation C2104T in the CARD15 gene (originally NOD2 gene) have been reported to be associated with Crohn's disease. Our aim was to investigate the occurrence of CARD15 gene polymorphisms in adult patients with periodontitis taking into account smoking and presence of putative periodontal pathogens as additional variables.

MATERIAL AND METHODS

A case-control study was performed in 104 Dutch Caucasian patients with severe adult periodontitis (54 non-smokers and 50 smokers, mean age 46 years) and in 97 ethnically matched, periodontal healthy controls (73 non-smokers and 24 smokers, mean age 40 years). DNA isolated from a mouthwash was typed with PCR technology. Presence of putative periodontal pathogens was established by culture technique.

RESULTS

Frequencies of the CARD15 3020insC and 2104T mutations were similar in the periodontitis group and in the control group (5.1% and 13.3%; 5.2% and 10.3%, respectively). The highest carrier frequency of CARD15 mutations was found in non-smoking patients without Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans (29.4% versus 17.4% in controls); however it did not reach statistical significance.

CONCLUSION

Our results suggest no role for CARD15 3020insC and C2104T mutations in adult periodontitis.

A combination of both arginine- and lysine-specific gingipain activity of Porphyromonas gingivalis is necessary for the generation of the micro-oxo bishaem-containing pigment from haemoglobin

The black pigment of Porphyromonas gingivalis is composed of the mu-oxo bishaem complex of Fe(III) protoporphyrin IX (mu-oxo oligomer, dimeric haem), namely [Fe(III)PPIX]2O. P. gingivalis W50 and Rgp (Arg-gingipain)- and Kgp (Lys-gingipain)-deficient mutants K1A, D7, E8 and W501 [Aduse-Opoku, Davies, Gallagher, Hashim, Evans, Rangarajan, Slaney and Curtis (2000) Microbiology 146, 1933-1940] were grown on horse blood/agar for 14 days and examined for the production of mu-oxo bishaem. Mu-oxo Bishaem was detected by UV-visible, Mössbauer and Raman spectroscopies in wild-type W50 and in the black-pigmented RgpA- and RgpB-deficient mutants (W501 and D7 respectively), whereas no haem species were detected in the straw-coloured colonies of Kgp-deficient strain K1A. The dark brown pigment of the double RgpA/RgpB knockout mutant (E8) was not composed of mu-oxo bishaem, but of a high-spin monomeric Fe(III) protoporphyrin IX species (possibly a haem-albumin complex). In vitro incubation of oxyhaemoglobin with cells of the W50 strain and the RgpA- and RgpB-deficient mutants (W501 and D7) resulted in the formation of mu-oxo bishaem via methaemoglobin as an intermediate. Although the Kgp-deficient strain K1A converted oxyhaemoglobin into methaemoglobin, this was not further degraded into mu-oxo bishaem. The double RgpA/RgpB knockout was also not capable of producing mu-oxo bishaem from oxyhaemoglobin, but instead generated a haemoglobin haemichrome. Inhibition of Arg-X protease activity of W50, W501, D7 and K1A with leupeptin, under conditions where Lys-X protease activity was unaffected, prevented the production of mu-oxo bishaem from oxyhaemoglobin, but resulted in the formation of a haemoglobin haemichrome. These results show that one or both of RgpA and RgpB gingipains, in addition to the lysine-specific gingipain, is necessary for the production of mu-oxo bishaem from haemoglobin by whole cells of P. gingivalis.

Quantitative microbiological study of subgingival plaque by real-time PCR shows correlation between levels of Tannerella forsythensis and Fusobacterium spp

A TaqMan-based real-time PCR assay was established to quantify the periodontopathic bacteria Tannerella forsythensis and Fusobacterium spp. With this assay, the prevalence and proportion of these bacteria in clinical specimens were evaluated. Our preliminary results suggest a positive colocalization of T. forsythensis and Fusobacterium spp. in periodontal pockets.

Periodontal Changes in Patients Undergoing Radiotherapy

BACKGROUND

The purpose of this study was to evaluate changes in the periodontium in patients who received head and neck radiation therapy.

METHODS

Periodontal clinical parameters (probing depth, clinical attachment level, gingival recession, plaque index, and bleeding on probing) were assessed on 27 patients before and 6 to 8 months following radiation therapy in the head and neck area.

RESULTS

The greatest changes occurred in clinical attachment level: overall, 70.3% of the patients showed a loss, with 92% evincing loss in the mandible. Attachment loss was directly related to the field of radiation and was greater when the jaws were actually included in the irradiated area.

CONCLUSION

Periodontal status should be evaluated prior to and following radiation therapy in the oral-maxillary-facial region to help ensure that periodontal health is maintained in oncology patients.

Intracellular localization of Porphyromonas gingivalis thiol proteinase in periodontal tissues of chronic periodontitis patients

OBJECTIVES

Porphyromonas gingivalis is a significant periodontal pathogen that has been shown in vitro to be able to invade gingival epithelial cells and grow intracellularly. The aim of the present study was to detect P. gingivalis in gingival tissues from chronic periodontitis (CP) patients.

MATERIALS AND METHODS

Monoclonal antibodies specific to a cell membrane-bound thiol proteinase of P. gingivalis were used to detect the microbe in gingival tissues of CP patients (n = 13) by immunohistochemistry. The presence of P. gingivalis was also analysed by polymerase chain reaction (PCR).

RESULTS

Immunohistochemical analysis of the periodontal tissues revealed positive staining for P. gingivalis thiol proteinase in 11 of the 13 patients. Positive staining was mainly located intracellularly in the perinuclear region of the cytoplasm in the periodontal epithelial cells and it could be detected throughout the whole depth of both pocket and oral epithelium. The sensitivity of immunohistochemistry was found to be comparable with that of PCR.

CONCLUSIONS

Our results provide in vivo evidence of the ability of P. gingivalis to enter human gingival epithelial cells. Intracellular localization of P. gingivalis contributes to its evasion of the host immune surveillance and eventually increases its resistance to conventional treatments of periodontal diseases.

Subgingival microbiota of chilean patients with chronic periodontitis

BACKGROUND

An association between race/ethnicity and the composition of the subgingival microbiota has been found in chronic periodontitis. A study was undertaken to determine the characteristics of the subgingival microbiota of chronic periodontitis in Chileans residing in Santiago.

METHODS

Twenty-six subjects (mean age 45 +/- 7 years) with chronic periodontitis, mean probing depth (PD) 2.63 +/- 0.5 mm, mean attachment level (AL) 3.70 +/- 0.77 mm, and without a history of periodontal therapy were selected. Measurements of PD, AL, bleeding on probing, and plaque accumulation were recorded at six sites per tooth. Subgingival plaque samples were taken from the mesial aspect of every tooth and evaluated for the presence, levels, and proportions of 40 bacterial taxa using whole genomic DNA probes and checkerboard DNA-DNA hybridization. The microbial data of the Chileans were compared with data from 115 chronic periodontitis patients from Boston, Massachusetts. Since several clinical and demographic parameters differed between the two populations, significance of differences for each species was determined using analysis of covariance, adjusting for age, plaque level, mean PD, gender, and smoking status.

RESULTS

Each of the individual test species was present in at least 25 of the 26 subjects, and 12 subjects (46.1%) harbored all 40 test species. With the exception of Prevotella intermedia, all test species colonized more than 75% of sites, and 25 species colonized > or = 90% of sites including the co-colonizing species of advanced periodontal lesions, termed the red complex, composed of the three species Porphyromonas gingivalis, Tannerella forsythensis (formerly Bacteroides forsythus), and Treponema denticola as well as Fusobacterium nucleatum subspecies, Campylobacter rectus, Peptostreptococcus micros, and Treponerma socranskii. Sixteen of the 40 species differed significantly between Chilean and U.S. subjects. Red, yellow, and other complexes were significantly higher in the Chileans, while the Actinomyces were higher in the U.S. subjects.

CONCLUSIONS

The composition of the subgingival plaque differs among different subject populations. Thus, care should be taken when extrapolating the findings of one study to different ethnic groups.

Update on human cytomegalovirus in destructive periodontal disease

AIM

Human cytomegalovirus (HCMV), a herpesvirus, is discussed in this review as it relates to destructive periodontal disease in humans.

RESULTS

HCMV genomic sequences, detected by polymerase chain reaction identification, occur with elevated frequency in severe adult periodontitis, localized and generalized aggressive (juvenile) periodontitis, Papillon-Lefèvre syndrome periodontitis, acute necrotizing ulcerative gingivitis, and periodontal abscesses.

DISCUSSION

Herpesviruses establish lifelong persistent infections. HCMV infection involves an asymptomatic latent phase interrupted by periods of recrudescence where viral replication and possibly clinical disease become manifest. HCMV reactivation is triggered by a number of immunosuppressive factors, some of which have been shown also to be risk factors/indicators of periodontitis. HCMV periodontal infection may cause release of tissue-destructive cytokines, overgrowth of pathogenic periodontal bacteria, and initiation of cytotoxic or immunopathologic events.

CONCLUSIONS

A growing body of data supports the concept that HCMV contributes to severe types of periodontal disease. HCMV infection of the periodontium may alter the immune control of resident microorganisms and be important in a multistage pathogenesis of periodontitis involving viral activation, periodontopathic bacteria, and host immune responses. Understanding the significance of HCMV and other herpesviruses in the development of periodontal disease may have important therapeutic implications. Vaccines against HCMV, which are in various stages of development, need to be evaluated for their ability to decrease the incidence of destructive periodontal disease.

Percent of plaque on individual tooth surfaces and differences in plaque area between adjacent teeth in healthy adults

OBJECTIVES

To apply a planimetric method to determine the percentage of the tooth area covered by plaque on individual tooth surfaces and to compare the percentage of plaque between adjacent tooth surfaces.

METHODS

Forty-three adults, mean age 43.0 years, with no signs of periodontal disease, participated. The subjects underwent comprehensive professional cleaning of all teeth. The subjects were then instructed to maintain their ordinary oral hygiene habits. Plaque was registered after 1 month, on each individual tooth surface by use of P%I.

RESULTS

The pattern of plaque accumulation was in large symmetrical, with differences in mean P%I between several adjacent tooth surfaces, e.g. for the maxillary buccal and lingual tooth surfaces between the first and second molars (P<0.001) and for the lingual tooth surfaces between the canines and the first premolars (P<0.01).

CONCLUSION

In the present study, it was possible to identify and describe adjacent tooth surfaces with the most pronounced plaque accumulation, to make further improvements of oral hygiene possible.

Antibiotic resistance profile of the subgingival microbiota following systemic or local tetracycline therapy

BACKGROUND

Tetracyclines have been extensively used as adjunctives to conventional periodontal therapy. Emergence of resistant strains, however, has been reported. This study evaluated longitudinally the tetracycline resistance patterns of the subgingival microbiota of periodontitis subjects treated with systemic or local tetracycline therapy+scaling and root planing (SRP).

METHODS

Thirty chronic periodontitis patients were randomly assigned to three groups: SRP+500 mg of systemic tetracycline twice/day for 14 days; SRP alone and SRP+tetracycline fibers (Actsite) at four selected sites for 10 days. Subgingival plaque samples were obtained from four sites with probing pocket depths (PPD)> or =6 mm in each patient at baseline, 1 week, 3, 6 and 12 months post-therapy. Samples were dispersed and diluted in pre-reduced anaerobically sterilized Ringer's solution, plated on Trypticase Soy Agar (TSA)+5% blood with or without 4 microg/ml of tetracycline and incubated anaerobically for 10 days. The percentage of resistant microorganisms were determined and the isolates identified by DNA probes and the checkerboard method. Significance of differences among and within groups over time was sought using the Kruskal-Wallis and Friedman tests, respectively.

RESULTS

The percentage of resistant microorganisms increased significantly at 1 week in the tetracycline groups, but dropped to baseline levels over time. The SRP+Actsite group presented the lowest proportions of resistant species at 6 and 12 months. No significant changes were observed in the SRP group. The predominant tetracycline-resistant species included Streptococcus spp., Veillonela parvula, Peptostreptococcus micros, Prevotella intermedia, Gemella morbillorum and Actinobacillus actinomycetemcomitans (Aa). A high percentage of sites with resistant Aa, Porphyromonas gingivalis and Tanerella forsythensis was observed in all groups at baseline. However, T. forsythensis was not detected in any group and P. gingivalis was not present in the SRP+Actsite group at 1 year post-therapy. Aa was still frequently detected in all groups after therapy. However, the greatest reduction was observed in the SRP+Actsite group.

CONCLUSION

Local or systemically administered tetracycline results in transitory selection of subgingival species intrinsically resistant to this drug. Although the percentage of sites harboring periodontal pathogens resistant to tetracycline were quite elevated in this population, both therapies were effective in reducing their prevalence over time.

Genetic analysis of Treponema denticola ATCC 35405 biofilm formation

Treponema denticola is a major aetiological organism implicated in periodontal disease. The interaction of T. denticola with other oral bacteria, in particular Porphyromonas gingivalis, in biofilm formation is thought to be an important step in the onset of periodontal disease. The interaction between T. denticola and P. gingivalis has been examined using a panel of T. denticola mutants and their effects on mixed biofilm formation tested in a static biofilm model. T. denticola ATCC 35405 did not form detectable biofilms on various inert surfaces. However, the spirochaete was demonstrated to form a biofilm with preattached P. gingivalis 381. T. denticola cfpA, which lacks the cytoplasmic filament, was unable to produce a mixed biofilm with P. gingivalis. A T. denticola flgE mutant which lacks the flagella hook protein and is therefore non-motile displayed a reduced, but readily detectable, ability to form a mixed biofilm as did the T. denticola mutant which does not possess the major outer sheath protein (Msp). The T. denticola lrrA mutant was only moderately defective in forming mixed biofilms with P. gingivalis. However, the T. denticola methyl-accepting chemotaxis protein (DmcA) did not appear to play a major role in mixed biofilm formation. In contrast, T. denticola lacking the PrtP protein for prolyl-phenylalanine-specific protease, showed an increased ability to form mixed biofilms and a prolonged viability in the biofilm.

Relationship of Subgingival and Salivary Microbiota to Gingival Overgrowth in Heart Transplant Patients Following Cyclosporin A Therapy

BACKGROUND

Severe gingival overgrowth (GO) is induced in patients taking cyclosporin A (CsA) following organ transplantation. Determining which patient will develop GO is still not possible. The purpose of this study was to establish an association between CsA and gingival overgrowth in heart transplant patients taking into account periodontal and microbiological conditions.

METHODS

Thirty patients (10 female, 20 male; range: 13 to 67 years; mean age: 44.89) undergoing CsA treatment were evaluated using the gingival index (GI), plaque index (PI), probing depth (PD), and clinical attachment level (CAL). Subgingival samples collected from the deepest site of each quadrant and saliva samples were submitted to microbial analysis. All patients had at least 12 teeth. Exclusion criteria were the use of antibiotics and/or having undergone periodontal treatment 6 months prior to the study. Patients were divided in two groups: with gingival (GO+) and without gingival overgrowth (GO-).

RESULTS

There were no statistically significant differences between the GO+ and GO- groups when CsA dosage, time since transplant, GI, PI, PD, and CAL were compared. Microbiological examination of the subgingival samples detected the following microorganisms: Actinobacillus actinomycetemcomitans (23%), Porphyromonas gingivalis (36%), Prevotella intermedia (93%), Fusobacterium sp. (66%), Campylobacter rectus (30%), Micromonas micros (66%), enteric rods (0%), and yeasts (30%). A positive association between M. micros and the GO+ group was found (P < 0.001). Yeasts were detected in 30% of the subgingival and saliva samples.

CONCLUSIONS

Clinical parameters were not sufficient to determine which patients would develop GO. However, colonization by M. micros might play a role in the etiology of GO.

Treponema putidum sp. nov., a medium-sized proteolytic spirochaete isolated from lesions of human periodontitis and acute necrotizing ulcerative gingivitis

So far, little phenotypic heterogeneity has been detected in cultured oral treponemes with trypsin-like proteolytic activity, and all have been assigned to the species Treponema denticola. However, comparisons of protein patterns and antigen expression in our collection of proteolytic oral treponemes occasionally identified isolates with a unique phenotype; e.g. strain OMZ 830 (=ATCC 700768), which qualified as a ‘pathogen-related oral spirochaete’ due to the presence of a ∼37 kDa protein reactive with the Treponema pallidum FlaA-specific mAb H9-2. In addition to such single isolates, a homogeneous group of seven independent strains is described that were highly motile, medium-sized, proteolytic but asaccharolytic spirochaetes and were cultured from human gingivitis, periodontitis and acute necrotizing ulcerative gingivitis in medium OMIZ-Pat supplemented with 1 % human serum and antibiotics. Growth of these spirochaetes in OMIZ-Pat was not dependent on, but was stimulated by, human or bovine serum. Carbohydrates were neither required nor stimulatory for growth. The protein and antigen patterns of total cell extracts of these organisms separated by SDS-PAGE were distinct from those of all previously cultured spirochaetes, with highest similarity to T. denticola. The novel spirochaete has a 2 : 4 : 2 arrangement of the periplasmic flagella, similar to T. denticola. However, the flagellin pattern as detected by immunostaining or glycan staining of Western blots readily distinguished the novel group from T. denticola. Also, distinct from reference strains of T. denticola, none of the novel isolates displayed sialidase or dentilisin activities, both of which are expressed by most strains of T. denticola. Trypsin-like activity and other enzymes as detected by API ZYM test were similar to those of T. denticola. The status of a novel species is supported by the 16S rRNA gene sequence, with 98·5 % similarity to its closest cultured relative, T. denticola. The name Treponema putidum sp. nov. is proposed (type strain OMZ 758T=ATCC 700334T=CIP 108088T).

A comparative evaluation of the clinical effects of systemic and local doxycycline in the treatment of chronic periodontitis

In this study, the clinical efficacies of systemic doxycycline (SD) and local doxycycline (LD) in the treatment of chronic periodontitis were compared. Forty-five patients were studied in 3 main groups with 5 treatments: SD alone, SD+scaling-root planing (SD+SRP), LD alone, LD+SRP and SRP alone. Antibiotic-treated patients were given doxycycline treatment alone in 1 quadrant of their upper jaws, and doxycycline+SRP was given in the contralateral quadrant. The areas included at least 4 teeth with > or = 5 mm pockets. Probing depth (PD), clinical attachment level, gingival index, sulcular bleeding index and plaque index values were recorded at baseline and the 7th week. The results were statistically analyzed. All of the clinical parameters were significantly reduced by all treatments (P < or = 0.05). The SD and LD treatments alone provided significant clinical healings. The significant differences among the groups were only in PD at the 7th week. The LD treatment provided significantly higher PD reduction than the SD treatment (P < or = 0.05). No significant difference was found between the SD+SRP and the LD+SRP treatments. There was no significant difference between SD+SRP and SRP alone treatment (P > 0.05). The SD group showed lower PD reduction than SRP group (P < or = 0.05), while no significant difference was found between LD and SRP treatments. The LD alone treatment seemed more effective than SD alone treatment on PD reduction, but no significant difference was found between them when combined with the SRP. LD may be more preferable than SD as an adjunct to mechanical treatment since LD seems more effective than SD on PD reduction and does not have the side effects of SD.

Oral health problems in elderly rehabilitation patients

A combination of poor oral hygiene and dry mouth may be hazardous to the oral health status. However, systematic assessments in order to detect oral health problems are seldom performed in the nursing care of the elderly. The aims of this study were to investigate the occurrence of oral health problems measured using the Revised Oral Assessment Guide (ROAG) and to analyse associations between oral health problems and age, gender, living conditions, cohabitation, reason for admission, number of drugs, and functional and nutritional status. One registered nurse performed oral health assessments using ROAG in 161 newly admitted elderly patients in rehabilitation care. Oral health problems were found in 71% of the patients. Thirty per cent of these patients had between four and eight problems. Low saliva flow and problems related to lips were the most frequent oral health problems. Problems in oral health status were significantly associated with presence of respiratory diseases (problems with gums, lips, alterations on the tongue and mucous membranes), living in special accommodation (low saliva flow, problems with teeth/dentures and alterations on the tongue), being undernourished (alterations on the tongue and low saliva flow) and being a woman (low saliva flow). The highest Odds ratio (OR) was found in problems with gums in relation with prevalence of respiratory diseases (OR 8.9; confidence interval (CI) 2.8-27.8; P < 0.0005). This study indicates the importance of standardised oral health assessments in order to detect oral health problems which can otherwise be hidden when the patients are admitted to the hospital ward.

A randomized clinical trial on the short-term clinical and microbiological effects of the adjunctive use of a 0.05% chlorhexidine mouth rinse for patients in supportive periodontal care

OBJECTIVE

To evaluate the clinical and microbiological activity of a new mouth rinse formulation, used as an adjunct to oral hygiene, for patients in supportive periodontal care.

PATIENTS AND METHODS

This was a randomized, placebo-controlled clinical trial with two groups: test group, rinsing twice per day with the test product (with 0.05% chlorhexidine and 0.05% cetylpyridinium chloride); and control group, rinsing with a placebo. Treated chronic periodontitis patients were included, and two visits were rendered, baseline, and after 15 days. Clinical outcome variables included plaque and gingival indices, and probing pocket depth. Subgingival samples were processed by culturing. Patient-based variables and adverse effects were also assessed. Outcome variables were compared by t-test, chi2, and Mann-Whitney test.

RESULTS

The results belonged to 33 patients. Plaque and gingival indices, and the log of bacterial total counts were reduced in the test group (p < or = 0.01), but differences between groups were only statistically significant (p < 0.05) for plaque and bacterial counts. A significant reduction in the proportions of flora (p < 0.05) and frequency of detection (p = 0.01) of Porphyromonas gingivalis was observed in the test group.

CONCLUSIONS

The newly formulated mouth rinse demonstrated short-term plaque-inhibitory activity. This was associated with a reduction in the total load of anaerobic subgingival microflora.

Gm (23) allotypes and Fcgamma receptor genotypes as risk factors for various forms of periodontitis

OBJECTIVES

Given the diversity of the distribution of the Gm (23) allotypes and FcgammaR genotypes in different ethnic groups, it was our purpose to examine their clinical significance in periodontitis in Taiwan.

MATERIAL & METHODS

Genomic DNA of 50 patients with chronic periodontitis (CP), 30 patients with generalized aggressive periodontitis (G-AP) and 74 healthy controls were harvested. The Gm (23) allotypes were determined by radial immunodiffusion test, and the FcgammaR IIa (CD32) and IlIb (CD16) genotypes were determined by polymerase chain reaction-based allele-specific oligonucleotide hybridization.

RESULTS

The overall carrier rate of the Gm (23+) allotype was higher than 85%, and the Gm (23-) allotype was statistically over-represented in patients with CP compared to the controls. There were no differences in the distributions of the three genotypes of FcgammaR IIa and IIIb among the three tested groups. The frequency of the R131 allele of the FcgammaR IIa polymorphisms was higher in G-AP than in CP when R/H allelic frequencies (p = 0.01) were examined by the chi2 test.

CONCLUSION

The Gm (23-) allotype might be a potential risk factor for CP. Although the R131 allele of FcgammaR IIa occurred more frequently in G-AP than in CP, its clinical significance could not be justified in this study.

Clinical effects of scaling and root planing in adults infected with Actinobacillus actinomycetemcomitans

The periodontal pathogen Actinobacillus actinomycetemcomitans can frequently be isolated from subgingival plaque of adults with chronic inflammatory periodontal disease and individuals with plaque-induced gingivitis. Problems with the persistence of the organism after thorough debridement of root surfaces have been reported. In the present study clinical effects of the hygienic phase of periodontal therapy in ten adult patients with moderate or advanced periodontitis harbouring A. actinomycetemcomitans were analysed. Since proper analysis of highly correlated data within a given patient is crucial for appropriate interpretation, a major objective of this study was to compare the results of different models derived from logistic regression of clinical and microbiological factors on gain or loss of clinical attachment under different assumptions. Subgingival samples from every tooth present were obtained before and 6 weeks after thorough subgingival scaling, and selectively cultivated for the organism. A relevant gain of clinical attachment of 2 mm or more was observed at a total of 36% of periodontitis sites after scaling. Overall, loss of attachment of 2 mm or more was observed at 8% sites. Most loss occurred at sites with gingival enlargement (15%), whereas 3% periodontitis sites lost 2 mm or more. In multivariate analyses erroneously assuming either independence of data or correctly considering the correlated structure of observations attachment gain was mainly associated with deep probing depths at the outset. Presence or absence of A. actinomycetemcomitans before or after therapy was not included into the periodontitis models. Also, loss of attachment of 2 mm or more after subgingival scaling was not influenced by the organism. A direct comparison of the results obtained with both approaches of logistic regression may be helpful in the assessment of the influence of the magnitude of correlation of the data on the regression coefficients.

Porphyromonas gingivalis 67-kDa fimbriae induced cytokine production and osteoclast differentiation utilizing TLR2

Porphyromonas gingivalis, a major etiological agent of adult periodontitis, has two distinctly different types of fimbriae on the cell surface. The major fimbriae, which consist of a 41-kDa fimbrillin of P. gingivalis ATCC 33277, have been known to induce inflammatory cytokine production in murine peritoneal macrophages. In this study, we examined the effects of the minor fimbriae of P. gingivalis, composed of a 67-kDa fimbrillin, on cytokine production in murine peritoneal macrophages and the ability to induce osteoclast differentiation. Murine peritoneal macrophages were stimulated with P. gingivalis 67-kDa minor fimbriae for 24 h, then the levels of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and IL-6 production were determined by enzyme-linked immunosorbent assay (ELISA). To estimate osteoclast differentiation, mouse osteoclast precursors were placed on dentine slices, and cultured with or without P. gingivalis 67-kDa minor fimbriae for 7 days. P. gingivalis 67-kDa minor fimbriae clearly induced IL-1beta, TNF-alpha and IL-6 production in mouse macrophages. Furthermore, pit formations on the dentine slices were significantly extended when the osteoclast precursors were incubated with P. gingivalis 67-kDa minor fimbriae. Pretreatment with anti-Toll-like receptor 2 (TLR2) antibody significantly inhibited IL-1beta, TNF-alpha and IL-6 induction (P<0.05) in mouse macrophages and pit-forming activity of osteoclast precursor cells stimulated with P. gingivalis 67-kDa minor fimbriae. These results suggest that P. gingivalis 67-kDa minor fimbriae may provoke host inflammatory response and be involved in periodontal tissue breakdown.

Periodontitis vaccine decreases local prostaglandin E2 levels in a primate model

Interleukin-1beta, tumor necrosis factor alpha, prostaglandin E2 (PGE2), and Porphyromonas gingivalis-specific immunoglobulin G levels in gingival crevicular fluid were measured in primates immunized with a P. gingivalis vaccine followed by ligature-induced periodontitis. Only PGE2 levels were dramatically suppressed (P < 0.0001) in immunized animals versus controls. A significant correlation (P < 0.027) was also found between PGE2 levels and decreased bone loss scores. This study presents the first evidence of a potential mechanism involved in periodontitis vaccine-induced suppression of bone loss in a nonhuman primate model and offers insight into the role of PGE2 in periodontal destruction.