Relationship between the percentage of subgingival spirochetes and the severity of periodontal disease

Surface protease of Treponema denticola hydrolyzes C3 and influences function of polymorphonuclear leukocytes

Treponema denticola is a dominant microorganism in human periodontal lesions. One of the major virulence factors of this microorganism is its chymotrypsin-like surface protease, dentilisin. The purpose of this study was to evaluate the effect of dentilisin on human polymorphonuclear leukocytes (PMNs). We used chemiluminescence to assess production of O(-)(2) by PMNs against T. denticola ATCC 35405 and dentilisin-deficient mutant K1. T. denticola ATCC 35405 induced production of O(-)(2), whereas dentilisin-deficient K1 did not. We found that chymostatin, a protease inhibitor, strongly reduced the ability of T. denticola ATCC 35405 to induce production of, O(-)(2), whereas K1 was relatively unaffected. We also used Immunoblot and ELISA to evaluate the activation of complement by this microorganism in relation to PMNs. T. denticola ATCC 35405 hydrolyzed the alpha-chain of C3, producing iC3b. Furthermore, strain ATCC 35405 induced a larger release of MMP-9 from PMNs than strain K1. Dentilisin activated PMNs via complement pathways and may play a role in establishing periodontal lesions.

Enfermedad periodontal necrosante: una manifestación de trastornos sistémicos

Necrotizing periodontal disease (NPD) is an infection characterized by gingival necrosis presenting as "punched-out" papillae, with gingival bleeding, and pain. Prevotella intermedia and spirochetes have been associated with the gingival lesions. Predisposing factors may include emotional stress, immunosuppression, especially secondary to human immunodeficiency virus (HIV) infection, cigarette smoking, poor diet and pre-existing gingivitis. During the last few years, diagnosis of NPD has became more important not only because of its contribution to the appearance of clinical attachment loss and gingival sequelae, but also because it has been revealed as a marker for immune deterioration in HIV-seropositive patients.

A systematic review of professional mechanical plaque removal for prevention of periodontal diseases

AIM

To investigate the effect of professional mechanical plaque removal (PMPR) on the prevention of periodontal diseases.

METHODS

We searched for randomized controlled trials, controlled clinical trials and cohort studies from 1950 to October 2004. Screening and data abstraction were conducted independently and in duplicate. Critical appraisal of studies was based on objective criteria and evidence tables were constructed.

RESULTS

From 2179 titles and abstracts, 132 full-text articles were screened and 32 studies were relevant. Evidence exists that PMPR in adults, particularly in combination with oral hygiene instruction (OHI), may be more effective than no treatment judged by surrogate measures. The evidence for a benefit of PMPR+OHI over OHI alone is less clear. The optimum frequency of PMPR has not been investigated although more frequent PMPR is associated with improved markers of health. The strength of evidence for these results ranges from weak to moderate due to risk of bias, inconsistent results, lack of appropriate statistics and small sample size.

CONCLUSIONS

There appears to be little value in providing PMPR without OHI. In fact, repeated OHI might have a similar effect as PMPR. Some forms of PMPR might achieve greater patient satisfaction. There is little difference in beneficial or adverse effects of different methods of PMPR.

Quantitative analysis of multi-species oral biofilms by TaqMan Real-Time PCR

Oral infectious diseases, including dental caries, various forms of periodontitis and oral malodor, are not caused by a single pathogen. The etiology of these diseases is known to be associated with bacterial accumulation and plaque composition on the hard and soft tissues of the oral cavity. Therefore, the quantitative, as well as qualitative, analysis of the microorganisms present in oral biofilms, namely dental plaque, subgingival plaque and tongue debris, is important for diagnosis and rational treatment decisions. The quantitative microbial analysis of oral multi-species biofilms also provides useful information for establishing the etiology of oral infectious diseases. Recently, a 5' fluorogenic, nuclease-based, real-time polymerase chain reaction (PCR) technique has been increasingly employed for the quantitative microbial assessment of the human oral cavity. We review the development and use of TaqMan real-time PCR for quantifying oral bacteria, its role in the diagnosis of oral infectious diseases and their microbial etiology.

Loop-mediated isothermal amplification method for rapid detection of the periodontopathic bacteria Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola

Loop-mediated isothermal amplification (LAMP), a novel nucleic acid amplification method, was developed for the rapid detection of the major periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. The LAMP method amplifies DNA with high specificity, efficiency, and rapidity under isothermal conditions using a set of four specially designed primers and a DNA polymerase with strand displacement activity. In this study, we initially designed the primers for LAMP assays to detect these bacteria and evaluated the specificity and sensitivity of these assays. The specificities of the primers for these bacteria were examined using various oral bacteria and various reaction times. The lower detection limits of the 60-min LAMP reaction without loop primers were 1 microg/tube for P. gingivalis, 10 fg/tube for T. forsythia, and 1 ng/tube for T. denticola. Addition of the loop primers for each bacterium improved the detection specificities and sensitivities by several magnitudes. Furthermore, LAMP assays were applied to the rapid detection of these periodontal pathogens in clinical specimens, and the results were compared with those of conventional PCR detection. The results of the LAMP assays corresponded to those of conventional PCR assays. These results indicate that the LAMP assay is an extremely rapid, highly sensitive, specific method. This method is very useful for the rapid detection of periodontopathic bacteria and the diagnosis of periodontal disease.

Treponema denticola immunoinhibitory protein induces irreversible G1 arrest in activated human lymphocytes

Oral spirochetes may contribute to the pathogenesis of a number of disorders including periodontal and periradicular diseases; however, the mechanism (s) by which these organisms act to cause disease is unknown. We have previously shown that extracts of the oral spirochete, Treponema denticola, contain an immunosuppressive protein (Sip) which impairs human lymphocyte proliferation. The objective of this study was to determine the mechanism by which Sip alters the proliferative response of lymphocytes. Human T-cells were activated by PHA in the presence or absence of Sip and cell cycle progression was assessed by flow cytometry. Cell cycle distribution was based upon DNA, RNA and protein content as well as expression of the activation markers; CD69 and IL-2R. Seventy-two hours following activation with PHA, cells were found in the G0, G1, S and G2/M phases of the cell cycle. In contrast, pretreatment with Sip resulted in a significant reduction of cells in the S and G2/M phases and a concomitant increase in the G1 phase. Sip did not alter the expression of the early activation markers CD69 and CD25R. To determine if G1 arrest resulted in activation of the checkpoint and cell death, we also monitored Sip-treated cells for apoptosis. Indeed, treatment with Sip resulted in both DNA fragmentation and caspase activation after 96 h. Our results indicate that Sip induces G1 arrest in human T-cells and, furthermore, that the arrest is irreversible, culminating in activation of the apoptotic cascade. We propose that if cell cycle arrest occurs in vivo, it may result in local and/or systemic immunosuppression and thereby enhance the pathogenicity of spirochetes and/or that of other opportunistic organisms.

TaqMan real-time polymerase chain reaction assay for the correlation of Treponema denticola numbers with the severity of periodontal disease

Treponema denticola has been implicated in periodontitis, and the presence of this organism in periodontal pockets has been investigated. However, qualitative analysis is insufficient for the clinical evaluation of periodontal treatments, and quantification of T. denticola populations is essential for monitoring therapeutic efficacy. Therefore, we developed a quantitative method for T. denticola that uses the TaqMan real-time polymerase chain reaction assay. Using this system, we evaluated the relative and absolute numbers of this organism in saliva and subgingival plaque. Furthermore, we analyzed the relationship between the numbers of T. denticola and pocket depth, and found a significant positive correlation (P < 0.0001) between these parameters. This report demonstrates the broad potential of real-time polymerase chain reaction applications in periodontology.

A 43-kDa protein ofTreponema denticolais essential for dentilisin activity

A protease of Treponema denticola, dentilisin, is thought to be part of a complex with 43- and 38-kDa proteins. A sequence encoding a 43-kDa protein was located in the 3' region of the prcA gene upstream of the dentilisin gene (prtP). The 43-kDa protein was apparently generated from digestion of PrcA. To clarify the function of the protein, we constructed a mutant of the 43-kDa protein following homologous recombination. The mutant lacked detectable dentilisin activity. Immunoblot analysis demonstrated that the dentilisin protein was degraded in the mutant. The results of real-time polymerase chain reaction suggested that prtP mRNA expression in the mutant was somewhat decreased compared with the wild-type strain. These data suggest that the 43-kDa protein is involved in the stabilization of the dentilisin protein.

Microbiological diagnostic testing in the treatment of periodontal diseases

A variety of microbiological diagnostic tests are available for clinicians to use for evaluation of patients with periodontal disease. Each one has its own unique set of advantages and disadvantages, and probably the most useful information for the clinician can be obtained using a combination of the various analytic methods. The tests appear to have their greatest utility when used on patients with chronic or aggressive periodontitis who do not respond favorable to conventional mechanical therapy. The major limitation of all microbiological tests is that the information obtained is relevant to the site sampled, and may not be representative of the microflora of the entire dentition. However, since it is often only specific sites that do not respond to initial therapy, knowing the constituents of the microflora that populate these sites is clinically relevant.

Tomographic reconstruction of treponemal cytoplasmic filaments reveals novel bridging and anchoring components

An understanding of the involvement of bacterial cytoplasmic filaments in cell division requires the elucidation of the structural organization of those filamentous structures. Treponemal cytoplasmic filaments are composed of one protein, CfpA, and have been demonstrated to be involved in cell division. In this study, we used electron tomography to show that the filaments are part of a complex with a novel molecular organization that includes at least two distinct features decorating the filaments. One set of components appears to anchor the filaments to the cytoplasmic membrane. The other set of components appears to bridge the cytoplasmic filaments on the cytoplasmic side, and to be involved in the interfilament spacing within the cell. The filaments occupy between 3 and 18% of the inner surface of the cytoplasmic membrane. These results reveal a novel filamentous molecular organization of independent filaments linked by bridges and continuously anchored to the membrane.

Molecular genetic analysis of the virulence of oral bacterial pathogens: an historical perspective

This review will focus on the impact of molecular genetic approaches on elucidating the bacterial etiology of oral diseases from an historical perspective. Relevant results from the pre- and post-recombinant DNA periods will be highlighted, including the roles of gene cloning, mutagenesis, and nucleotide sequencing in this area of research. Finally, the impact of whole-genome sequencing on deciphering the virulence mechanisms of oral pathogens, along with new approaches to control these organisms, will be discussed.

Evaluation of enamel matrix derivative as an adjunct to non-surgical periodontal therapy

OBJECTIVES

The aim of this study was to evaluate the adjunctive use of enamel matrix derivative (EMD) on periodontal healing following nonsurgical periodontal therapy (scaling and root planing - SRP).

MATERIAL AND METHODS

The study was performed as an intraindividual, longitudinal trial of 3 months duration with a double-blinded, split-mouth, controlled, and randomized design. Twenty-two patients with moderate to severe chronic periodontitis were enrolled in the study. In each patient, two sites with pocket depths >/=5 mm and with radiographic angular bone defects >3 mm were selected. Baseline examination included measurement of probing pocket depth (PPD) and clinical attachment levels (CAL). The presence or absence of plaque and bleeding on probing at selected sites was also recorded. Following initial examination, full-mouth SRP was performed. Study sites were then treated with 24% EDTA for 2 min, followed by thorough irrigation with sterile saline. The sites were then randomized. The experimental site received subgingival application of enamel matrix derivative (Emdogain, BIORA AB, Malmo, Sweden). The control site received no additional treatment. At 3 months, all sites were re-examined. The response to therapy in experimental and control sites was evaluated, using change in probing depth and CAL as the primary outcome variables. Statistical analysis (paired t-tests) was used to compare response to treatment in control versus experimental sites.

RESULTS

Statistically significant changes in PPD and CAL were seen in both treatment groups from baseline to 3 months. The mean PPD reduction was 2.3+/-0.5 mm for control sites and 2.0+/-0.3 mm for experimental sites. The mean CAL gain was 1.8+/-0.4 mm for control sites, and 1.4+/-0.3 mm for experimental sites. Statistical analysis, however, revealed no significant difference in PPD reduction or CAL gain between experimental and control groups (p>0.4). In addition, no difference was found between treatment groups in bleeding or plaque indices at 3 months.

CONCLUSION

The findings from the present study do not support the use of EMD during routine, nonsurgical debridement of periodontal pockets as measured 3 months post SRP.

Subgingival microbiota of renal transplant recipients

Renal transplant patients undergoing immunosuppressive therapy may experience periodontal side-effects such as gingival overgrowth. This study evaluated the subgingival microbiota of renal transplant recipients with or without periodontal tissue destruction who may have concurrent gingival enlargement. Subgingival paper point samples taken from the deepest probing sites of 38 subjects (one per patient) were examined using direct microscopy and culture techniques. A complex microflora comprising gram-positive and gram-negative cocci, rods and filaments, fusiforms, curved rods and spirochetes was observed using microscopy. Yeasts were occasionally detected. Significantly higher proportions of gram-positive morphotypes, including gram-positive cocci, were observed in samples from periodontally healthy patients. The predominant cultivable microflora from anaerobic culture comprised several species of facultative and obligate anaerobes. Colonization of the subgingival sites by 'foreign' microbes that are normally dermal, intestinal or vaginal flora was detected in up to 50% of the samples. High mean proportions of lost or unidentified species were also occasionally noted. The results showed that the subgingival biofilm of renal transplant recipients with chronic periodontitis comprised mainly gram-negative rods and spirochetes. Besides the usual predominant cultivable subgingival microbiota associated with periodontitis, the high prevalence of unidentified and 'foreign' microbes indicates the possibility of subgingival microbial alteration in renal transplant patients.

Clinical evaluation of an Er:YAG laser combined with scaling and root planing for non-surgical periodontal treatment. A controlled, prospective clinical study

OBJECTIVES

The purpose of the present controlled clinical trial was to compare the treatment of advanced periodontal disease with a combination of an Er:YAG laser (KEY II, KaVo, Germany) and scaling and root planing with hand instruments (SRP) to laser alone.

MATERIAL AND METHODS

Twenty healthy patients with moderate to advanced periodontal destruction were randomly treated in a split-mouth design with a combination of an Er:YAG laser and SRP (test) or with laser (control) alone. The used energy setting for laser treatment was 160 mJ/pulse at a repetition rate of 10 Hz. Prior to treatment and 3, 6 and 12 months later the following parameters were evaluated by a blinded examiner: Plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR) and clinical attachment level (CAL). Subgingival plaque samples were taken at each appointment and analysed using darkfield microscopy for the presence of cocci,-non-motile rods, motile rods and spirochetes. No statistical significant differences in any of the investigated parameters between both groups were observed at baseline.

RESULTS

Initially, the plaque index was 1.0 +/- 0.6 in both groups. At the 3-month examination the plaque scores were markedly reduced and remained low throughout the study. A significant reduction of the GI and BOP occurred in both groups after 3, 6 and 12 months (P < 0.05, P < 0.05, respectively). The mean PD decreased in the test group from 5.2 +/- 0.8 mm at baseline to 3.2 +/- 0.8 mm after 12 months (P < 0.05) and in the control group from 5.0 +/- 0.7 mm at baseline to 3.3 +/- 0.7 mm after 12 months (P < 0.05). The mean CAL decreased in the test group from 6.9 +/- 1.0 mm at baseline to 5.3 +/- 1.0 mm after 12 months (P < 0.05) and in the control group from 6.6 +/- 1.1 mm at baseline to 5.0 +/- 0.7 after 12 months (P < 0.05). Both groups showed a significant increase of cocci and-non-motile rods and a decrease in the amount of motile rods and spirochetes.

CONCLUSION

In conclusion, the present results have indicated that: (i) non-surgical periodontal therapy with both an Er:YAG laser + SRP and an Er:YAG laser alone may lead to significant improvements in all clinical parameters investigated, and (ii) the combined treatment Er:YAG laser + SRP did not seem to additionally improve the outcome of the therapy compared to Er:YAG laser alone.

Treponema denticola may stimulate both epithelial proliferation and apoptosis through MAP kinase signal pathways

Mitogen-activated protein kinases (MAP kinases) play a key role in the regulation of cell survival and death. Effects of Treponema denticola ATCC 35405 on ERK, p38 and JNK MAP kinases, and cell behavior was studied using non-keratinizing periodontal ligament epithelial cells (PLE) in vitro. Compared to Chinese hamster ovary cells, human cervix adenocarcinoma cells, human osteosacroma cells and human gingival fibroblasts, PLE cells were much more resistant to T. denticola-induced reduction in cell viability, assayed by tetrazolium and crystal violet assays. A low dose of 5 x 10(7) T. denticola cells/ml increased DNA synthesis ([3H]thymidine uptake) in PLE cells but at higher concentrations DNA synthesis was decreased. TUNEL staining analysis showed that about 50% of epithelial cells in onolayers died through apoptosis when exposed to a high dose of 10(11) T. denticola/ml for 24 h. Morphological light and electron microscopic analysis supported the idea that both apoptotic and necrotic cell death took place. Rounding, membrane damage, fragmentation and detachment were observed in selective cells of both mono- and multilayered PLE cultures challenged with T. denticola. Western blot analysis using MAP kinase phosphospecific antibodies showed that T. denticola strongly but transiently activated ERK1 and ERK2, signals mediating cell proliferation, and JNK and p38, kinases mediating apoptosis. While a specific inhibitor of the ERK MAP kinase pathway prevented the T. denticola stimulation of cell proliferation, inhibitor of p38 increased the cell numbers in T. denticola-treated cultures. The results suggest that T. denticola activates epithelial cell MAP kinase signal pathways controlling cell proliferation and cell survival. In addition, T. denticola exerts cytotoxic effects that appear to predominate at higher bacterial concentrations.

Treponema denticola is resistant to human beta-defensins

Spirochetes, including Treponema denticola, are implicated in the pathogenesis of periodontal disease. Because T. denticola lacks lipopolysaccharides that serve as targets for human beta-defensin (h beta D) binding, we postulated that T. denticola would resist killing by h beta D. We showed that T. denticola is resistant to h beta D-1 and -2. Protease inhibitors did not enhance killing of T. denticola by h beta D-2, suggesting that degradation of h beta D-2 by treponemal proteases is not a major factor in T. denticola resistance.

Role of Treponema denticola in periodontal diseases

Among periodontal anaerobic pathogens, the oral spirochetes, and especially Treponema denticola, have been associated with periodontal diseases such as early-onset periodontitis, necrotizing ulcerative gingivitis, and acute pericoronitis. Basic research as well as clinical evidence suggest that the prevalence of T denticola, together with other proteolytic gram-negative bacteria in high numbers in periodontal pockets, may play an important role in the progression of periodontal disease. The accumulation of these bacteria and their products in the pocket may render the surface lining periodontal cells highly susceptible to lysis and damage. T. denticola has been shown to adhere to fibroblasts and epithelial cells, as well as to extracellular matrix components present in periodontal tissues, and to produce several deleterious factors that may contribute to the virulence of the bacteria. These bacterial components include outer-sheath-associated peptidases, chymotrypsin-like and trypsin-like proteinases, hemolytic and hemagglutinating activities, adhesins that bind to matrix proteins and cells, and an outer-sheath protein with pore-forming properties. The effects of T. denticola whole cells and their products on a variety of host mucosal and immunological cells has been studied extensively (Fig. 1). The clinical data regarding the presence of T. denticola in periodontal health and disease, together with the basic research results involving the role of T. denticola factors and products in relation to periodontal diseases, are reviewed and discussed in this article.

Clinical evidence for the efficacy and safety of powered toothbrushes

Powered toothbrushes are becoming increasingly popular among the general population, and there are many models on the market from which to choose. The design of these toothbrushes is changing constantly, as one would expect with a developing and expanding market, and from the dental professional's standpoint, it is difficult to evaluate products from the literature simply because the designs of clinical trials for powered toothbrushes are so varied. For example, the cohort recruited for testing the products is seldom the same from one study to the next. The aim of this paper is to provide a brief overview of the findings from some of the more contemporary trials of powered toothbrushes and to examine some of the factors that might have an effect on the observations and outcomes.

Testing the efficacy of 2 prototype brush heads for a powered toothbrush: refining the model

OBJECTIVES

To compare 2 prototype powered toothbrush (PTB) heads (A, B) to a marketed head (Sensiflex 2000) for plaque removing efficacy on the Philips/Jordan HX2550 PTB.

MATERIALS AND METHODS

A 2-week, 3-group, single-blind trial recruited 78 volunteers (18-25). Plaque indices (PIs) were recorded at screening and 14 days later at baseline. Subjects were stratified (gender and PI) and then asked to abstain from oral hygiene measures for 48 h. A supervised episode of brushing with the allocated PTB head followed. Subjects then used the PTBs at home for the next 12 days before being asked to abstain from all oral hygiene measures for another 48 h prior to a second supervised brushing episode. Plaque was scored using a new modification of the Quigley & Hein Index (PI) at full mouth (FM), interproximal (IP) and smooth surfaces (SS). PIs were recorded before and after the supervised brushing episodes to enable the means of the within subject differences (pre- to post-brushing) to be compared between groups (ANOVA/t-tests).

RESULTS

There were no significant differences in PI between groups at baseline or prior to the supervised brushings (p>0.05). Highly significant, mean reductions in PIs (approximately 1/2 of one PI unit) were observed for design B compared with the Sensiflex 2000 at FM and IP sites (p<0.0001) for both supervised brushing episodes. A significant reduction in PI at SS was seen only after the first brushing episode (p=0.0004). For design A, PI reductions were consistently greater than those for the Sensiflex 2000 but differences were only significant at the p<0.05 level.

CONCLUSION

It is concluded that this model of clinical trial has sufficient power to demonstrate clinical superiority with respect to plaque removal for PTBs and can be used for testing one or more prototype designs of brush heads.

Sulfate-reducing bacteria in relation with other potential periodontal pathogens

BACKGROUND, AIMS

Oral sulfate-reducing bacteria are involved in several clinical categories of periodontitis. The aim of this cross-sectional study was to compare the presence of sulfate-reducing bacteria (SRB) with other putative pathogens including spirochetes, Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis, and Treponema denticola in periodontal lesions.

METHOD

Periodontal SRB were detected by enrichment culture and compared with a microscopic spirochete count (n=168). Species-specific oligonucleotide probes directed against the 16S rRNA were employed to determine the presence of A. actinomycetemcomitans, P. gingivalis, B. forsythus, and T. denticola (n=55).

RESULTS

A significant positive correlation was observed between the presence of SRB and the proportions of spirochetes in subgingival plaque, although the 2 bacterial groups also occurred separately. SRB tended to be negatively correlated with the presence of A. actinomycetemcomitans. In contrast, all pockets with SRB harbored either T. denticola, or both T. denticola and B. forsythus (12/14) before therapy. Interestingly, the combination of SRB with P. gingivalis occurred in 32% of the periodontal pockets before treatment. After initial periodontal therapy, the prevalence of this combination was reduced to 2% of the sites, and to 25% of the sites in recall patients.

CONCLUSION

The presence of SRB was positively correlated with T. denticola, B. forsythus, and P. gingivalis in periodontal lesions. These suspected pathogens form a complex strongly associated with destructive periodontitis.

Periodontal disease as a specific, albeit chronic, infection: diagnosis and treatment

Periodontal disease is perhaps the most common chronic infection in adults. Evidence has been accumulating for the past 30 years which indicates that almost all forms of periodontal disease are chronic but specific bacterial infections due to the overgrowth in the dental plaque of a finite number of mostly anaerobic species such as Porphyromonas gingivalis, Bacteroides forsythus, and Treponema denticola. The success of traditional debridement procedures and/or antimicrobial agents in improving periodontal health can be associated with the reduction in levels of these anaerobes in the dental plaque. These findings suggest that patients and clinicians have a choice in the treatment of this overgrowth, either a debridement and surgery approach or a debridement and antimicrobial treatment approach. However, the antimicrobial approach, while supported by a wealth of scientific evidence, goes contrary to centuries of dental teaching that states that periodontal disease results from a "dirty mouth." If periodontal disease is demonstrated to be a risk factor for cardiovascular disease and stroke, it will be a modifiable risk factor since periodontal disease can be prevented and treated. Since the antimicrobial approach may be as effective as a surgical approach in the restoration and maintenance of a periodontally healthy dentition, this would give a cardiac or stroke patient and his or her physician a choice in the implementation of treatment seeking to improve the patient's periodontal condition so as to reduce and/or delay future cardiovascular events.

Cloning and expression of two novel hemin binding protein genes from Treponema denticola

Treponema denticola does not appear to produce siderophores, so it must acquire iron by other pathways. Indeed, T. denticola has been shown to have an iron-regulated 44-kDa outer membrane protein (HbpA) with hemin binding ability. To characterize the HbpA protein, its gene was cloned from genomic DNA libraries of T. denticola. Sequence analysis of the hbpA open reading frame indicated that it encoded a 42.8-kDa protein with a 23-amino-acid signal peptide. HbpA has no significant homology to any proteins in the databases. Southern blot analysis demonstrated that hbpA is present in several T. denticola ATCC strains and clinical isolates, but not in Treponema pectinovorum, Treponema socranskii, or Escherichia coli. HbpA, expressed as a recombinant protein in E. coli and purified by antibody affinity chromatography, has hemin binding activity as determined by lithium dodecyl sulfate-polyacrylamide gel electrophoresis with tetramethylbenzidine staining. Northern blot analysis showed that there were two hbpA-containing transcripts, of approximately 1.3 and 2.6 kb, and that the RNA levels were low-iron induced. Interestingly, the 2.6-kb mRNA also encoded a second protein with significant homology to hbpA. This downstream gene, called hbpB, was cloned and sequenced and its product was expressed as a fusion protein in E. coli. The hbpB gene product is 49% identical to HbpA and binds hemin. Thus, T. denticola has two novel hemin binding proteins which may be part of a previously unrecognized iron acquisition pathway.

Periodontal treatment with an Er: YAG laser compared to scaling and root planing. A controlled clinical study

BACKGROUND

The aim of the present study was to compare the effectiveness of an Er:YAG laser to that of scaling and root planing for non-surgical periodontal treatment.

METHODS

Twenty patients with moderate to advanced periodontal destruction were treated under local anesthesia and the quadrants were randomly allocated in a split-mouth design to either Er:YAG laser using an energy level of 160 mJ/pulse and 10 Hz or scaling and root planing (SRP) using hand instruments. Clinical assessments of plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR), and clinical attachment level (CAL) were made prior to and at 3 and 6 months after treatment. Subgingival plaque samples were taken at each appointment and analyzed using darkfield microscopy for the presence of cocci, non-motile rods, motile rods, and spirochetes. Differences in clinical parameters and prevalence of bacterial species were analyzed using the paired t-test.

RESULTS

The PI remained nearly unchanged while a significant reduction of the GI occurred in both groups after 6 months (P < or =0.001, P< or =0.001, respectively). The mean value of BOP decreased in the laser group from 56% at baseline to 13% after 6 months (P < or =0.001) and in the SRP group from 52% at baseline to 23% after 6 months (P < or =0.001). The mean value of the PD decreased in the laser group from 4.9+/-0.7 mm at baseline to 2.9+/-0.6 mm after 6 months (P< or =0.001) and in the SRP group from 5.0+/-0.6 mm at baseline to 3.4+/-0.7 mm after 6 months (P < or =0.001). The mean value of the CAL decreased in the laser group from 6.3+/-1.1 mm at baseline to 4.4+/-1.0 mm after 6 months (P < or =0.001) and in the SRP group from 6.5+/-1.0 mm at baseline to 5.5+/-1.0 after 6 months (P < or =0.001). The reduction of the BOP score and the CAL improvement was significantly higher in the laser group than in the SRP group (P < or =0.05, P < or =0.001, respectively). Both groups showed a significant increase of cocci and non-motile rods and a decrease in the amount of motile rods and spirochetes.

CONCLUSIONS

An Er:YAG laser may represent a suitable alternative for non-surgical periodontal treatment.

Taxonomy and virulence of oral spirochetes

All oral spirochetes are classified in the genus Treponema. This genus is in the family Spirochaetaceae as in Bergey's manual of systematic bacteriology. Other generic members of the family include Spirochaeta, Cristispira and Borrelia. This conventional classification is in accord with phylogenetic analysis of the spirochetes based on 16S rRNA cataloguing. The oral spirochetes fall naturally within the grouping of Treponema. Only four species of Treponema have been cultivated and maintained reliably: Treponema denticola, Treponema pectinovorum, Treponema socranskii and Treponema vincentii. These species have valid names according to the rules of nomenclature except for Treponema vincentii, which only has had effective publication. The virulence factors of the oral spirochetes updated in this mini-review have been discussed within the following broad confines: adherence, cytotoxic effects, iron sequestration and locomotion. T. denticola has been shown to attach to human gingival fibroblasts, basement membrane proteins, as well as other substrates by specific attachment mechanisms. The binding of the spirochete to human gingival fibroblasts resulted in cytotoxicity and cell death due to enzymes and other proteins. Binding of the spirochete to erythrocytes was accompanied by agglutination and lysis. Hemolysis releases hemin, which is sequestered by an outer membrane sheath receptor protein of the spirochete. The ability to locomote through viscous environments enables spirochetes to migrate within gingival crevicular fluid and to penetrate sulcular epithelial linings and gingival connective tissue. The virulence factors of the oral spirochetes proven in vitro underscore the important role they play in the periodontal disease process. This role has been evaluated in vivo by use of a murine model.

Necrotizing ulcerative gingivitis

Necrotizing periodontal diseases are unique in their clinical presentation and course. Data suggest that the etiology and pathogenesis of necrotizing periodontal diseases may also be distinctive from other periodontal diseases. Necrotizing ulcerative gingivitis (NUG) is a type of necrotizing periodontal disease in which the necrosis is limited to the gingival tissues. Three specific clinical characteristics must be present to diagnose NUG, pain (usually of rapid onset) interdental necrosis, and bleeding. Epidemiological and prospective clinical studies have found an altered ability to cope with psychological stress, immunosuppression, and tobacco use to be strongly associated with the onset of NUG.

Lack of humoral immune protection against Treponema denticola virulence in a murine model

This study investigated the characteristics of humoral immune responses to Treponema denticola following primary infection, reinfection, and active immunization, as well as immune protection in mice. Primary infection with T. denticola induced a significant (400-fold) serum immunoglobulin G (IgG) response compared to that in control uninfected mice. The IgG response to reinfection was 20, 000-fold higher than that for control mice and 10-fold higher than that for primary infection. Mice actively immunized with formalin-killed treponemes developed serum antibody levels seven- to eightfold greater than those in animals after primary infection. Nevertheless, mice with this acquired antibody following primary infection or active immunization demonstrated no significant alterations of lesion induction or decreased size of the abscesses following a challenge infection. Mice with primary infection developed increased levels of IgG3, IgG2b, and IgG2a antibodies, with IgG1 being lower than the other subclasses. Reinfected mice developed enhanced IgG2b, IgG2a, and IgG3 and less IgG1. In contrast, immunized mice developed higher IgG1 and lower IgG3 antibody responses to infection. These IgG subclass distributions indicate a stimulation of both Th1 and Th2 activities in development of the humoral immune response to infection and immunization. Our findings also demonstrated a broad antigen reactivity of the serum antibody, which was significantly increased with reinfection and active immunization. Furthermore, serum antibody was effective in vitro in immobilizing and clumping the bacteria but did not inhibit growth or passively prevent the treponemal infection. These observations suggest that humoral immune responses, as manifested by antibody levels, isotype, and antigenic specificity, were not capable of resolving a T. denticola infection.

Molecular epidemiology of oral treponemes associated with periodontal disease

Periodontitis, a disease responsible for tooth loss worldwide, is characterized by chronic inflammation of the periodontium, eventually leading to destruction of periodontal ligaments and supporting alveolar bone. Spirochetes, identified by dark-field microscopy as being the most predominant bacteria in advanced lesions, are thought to play a causative role. Various spirochetal morphotypes were observed, but most of these morphotypes are as yet uncultivable. To assess the role of these organisms we designed oligonucleotide probes for the identification of both cultivable and so far uncultivable spirochetes in periodontitis patients. Subgingival plaque specimens taken from diseased sites (n = 200) and healthy control sites (n = 44) from 53 patients with rapidly progressive periodontitis (RPP) were submitted to direct in situ hybridization or dot blot hybridization after prior amplification with eubacterial primers. Spirochetes were found in all patients, but their distributions varied considerably. Parallel use of oligonucleotide probes specific for cultivable or so far uncultivable treponemes suggested the presence of novel yet unknown organisms at a high frequency. These uncultivable treponemes were visualized by fluorescence in situ hybridization, and their morphologies, sizes, and numbers could be estimated. All RPP patients included in this study harbored oral treponemes that represent either novel species, e.g., Treponema maltophilum, or uncultivable phylotypes. Therefore, it is necessary to include these organisms in etiologic considerations and to strengthen efforts to cultivate these as yet uncultivable treponemes.

Virulence characteristics of oral treponemes in a murine model

This study was designed to investigate the virulence characteristics of Treponema denticola, T. socranskii, T. pectinovorum, and T. vincentii following challenge infection of mice. These microorganisms induced well-demarcated, dose-dependent, raised subcutaneous (s.c.) abscesses which were similar in time of onset, lesion progression, and duration of healing. Only viable cells were capable of inducing these characteristic s.c. abscesses. Histological examination of the skin lesion 3 and 5 days postinfection revealed abscess formation in the s.c. tissues, and abundant spiral organisms were demonstrated to be present in the abscess. Host resistance modulation by dexamethasone (neutrophil alteration) and cyclophosphamide (neutrophil depletion) pretreatment had a minimal effect on the virulence expression by any of these treponemes. The T. denticola isolates demonstrated significant trypsin-like protease (TLPase) activity, while both T. socranskii and T. vincentii were devoid of this activity. Interestingly, T. pectinovorum strains were heterogeneous with respect to TLPase as high producers, low producers, and nonproducers. However, no differences in lesion formation were noted regardless of whether the species expressed this proteolytic activity or whether treatment with N alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) and dithiothreitol was performed. These results showed that (i) a murine model may be used to evaluate virulence expression by oral treponemes; (ii) while TLPase activity varies among the oral treponemes, this protease does not appear to participate in abscess induction in the mouse model; and (iii) T. pectinovorum strains show variation in TLPase activity.

Clinical and microbiological effects of minocycline-loaded microcapsules in adult periodontitis

Clinical and microbiological effects of subgingival delivery of 10% minocycline-loaded (MC), bioabsorbable microcapsules were examined in 15 adult periodontitis patients. Patients received oral hygiene instruction 2 weeks prior to the study. At baseline (day 0) all teeth received supragingival scaling (SC); 2 quadrants received no further treatment and 1 quadrant received subgingival scaling and root planning (SRP). In the fourth quadrant, the tooth with the deepest probing sites (at least 1 site > or = 5 mm) was treated with minocycline microcapsules. The sites were evaluated at baseline and weeks 1, 2, 4, and 6. Clinical indices included bleeding on probing (BOP), probing depths (PD), and attachment loss (AL). Microbiological evaluations included percent morphotypes by phase-contrast microscopy; cultivable anaerobic, aerobic, and black-pigmented Bacteroides (BPB); and percent Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, and Actinomyces viscosus by indirect immunofluorescence. In the SC + MC group, BOP, PD, and AL were significantly reduced from baseline for weeks 1 to 6. BOP in the SC + MC group was significantly reduced compared to the SRP group from weeks 2 to 6. In the SC + MC group the percent of spirochetes and motile rods decreased and the percent of cocci increased after 1 week. The increased cocci and decreased motile rods were statistically greater at weeks 4 and 6 in the SC + MC group compared to the SRP group. This study demonstrates that local subgingival delivery of 10% minocycline-loaded microcapsules as an adjunct to scaling results in reduction in the percent sites bleeding on probing greater than scaling and root planning alone and induces a microbial response more favorable for periodontal health than scaling and root planing.

Differential attachment of oral treponemes to monolayers of epithelial cells

This in vitro study describes the attachment properties of several oral treponemes to monolayers of epithelial cells and the effect of epithelial cell confluence on treponeme attachment. Four serotypes of Treponema denticola, Treponema scoliodontum, three subspecies of Treponema socranskii, and Treponema vincentii were tested with monolayers of epithelial cells of human and canine origin. Attachment of oral treponemes were compared to attachment by T. pallidum subsp. pallidum, and by the non-pathogen Treponema phagedenis. Results indicated that different serotypes of T. denticola had similar abilities to attach to epithelial cells. However, subspecies of T. socranskii differed in their ability to attach to epithelial cells. The proportion of epithelial cells susceptible to attachment by oral spirochetes was strongly related to the confluence level of the monolayer. In contrast, T. pallidum attached equally well to both epithelial cell lines at all confluence levels. T. phagedenis attached to < 1% of all epithelial cells. In general, attachment of oral treponemes to canine cells was lower than to human cells, suggesting species-specificity for adherence. Attachment of oral treponemes to epithelial cells may promote colonization of the periodontal pocket, as well as retention of treponeme colonies within plaque. The preference of oral treponemes to attach to cells of low confluence fields may translate in vivo to an increased ability to attach to cells which are actively dividing. Such cells are found in areas of repair, a common status within inflamed periodontal pockets. Furthermore, attachment of oral treponemes to epithelial cell barriers may promote or potentiate cytopathic processes.

Identification, isolation, and characterization of the 42-kilodalton major outer membrane protein (MompA) from Treponema pectinovorum ATCC 33768

The major protein present in the isolated outer membrane of Treponema pectinovorum ATCC 33768, MompA, was identified, purified, and characterized. Immuno-gold electron microscopy, using anti-MompA serum, and cell fractionation experiments confirmed the localization of MompA to the outer membrane. MompA was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to have a molecular mass of 42 kDa when heat denatured, whereas native MompA formed a number of detergent-stable forms with molecular masses of 71, 76, and 83 kDa. A temperature of 60 degrees C was required to convert the native protein to the 42-kDa form. A number of detergents and chemical agents that are capable of breaking ionic and hydrogen bonds of proteins did not convert native MompA to the 42-kDa species. The native forms of the protein were resistant to the combined action of proteinase K, trypsin, and chymotrypsin, whereas the 42-kDa form of MompA was not. The N-terminal amino acid sequence of MompA was determined to be DVTVNINSRVRPVLYTT, and database searches did not identify any homology with known protein sequences. Amino acid compositional analysis showed the protein to be rich in proline and glycine, with these amino acids accounting for 28 and 13%, respectively, of the total amino acids. Antiserum raised against the major outer membrane protein of T. denticola GM-1 and ATCC 35405 did not cross-react with MompA, and antiserum raised against MompA did not react with any cellular components of Treponema denticola, Treponema vincentii, or Treponema socranskii. A major outer membrane protein similar in molecular mass to MompA was identified in eight clinical isolates of T. pectinovorum. The major outer membrane protein produced by four of the clinical isolates reacted strongly, by Western blotting, with anti-MompA serum, whereas proteins of the other strains did not.

Antimicrobial susceptibility tests on anaerobic oral mixed cultures in periodontal diseases

The ecosystem of the dental plaque in periodontal diseases is very complex: the study of such micro-organisms, which are mostly strict anaerobes, requires the use of specific techniques under conditions of strict anaerobiosis. The aim of the present study was to design a rapid method to evaluate the activity of antimicrobials on mixed bacterial plaque of subjects with periodontal diseases. The study was carried out using a computerised instrument generally used for simultaneous diagnostic tests with aerobic bacteria. Operative and methodological modifications were made to obtain conditions of strict anaerobiosis and the balanced growth of all the microbial forms present in the mixed cultures of the plaque. Penicillins and cephalosporins were active on all the samples, whereas colistin, gentamicin, kanamycin and nalidixic acid showed no activity. Clindamycin, tetracycline, erythromycin and penicillin G were effective only against some samples. The activity of the antimicrobials towards isolated strains was analogous to that towards the corresponding mixed culture.

Release and activation of human neutrophil matrix metallo- and serine proteinases during phagocytosis of Fusobacterium nucleatum, Porphyromonas gingivalis and Treponema denticola

The phagocytic ingestion of reference strains and clinical isolates of Fusobacterium nucleatum, Porphyromonas gingivalis, and Treponema denticola by polymorphonuclear leukocytes (PMNs) and the concomitant release of PMN granule proteinases were studied by specific functional and immunological assays. PMNs were incubated with the microorganisms anaerobically at 37 degrees C for indicated time periods. The suspensions and pellets were used for phagocytic ingestion assay and electron microscopic study, respectively. The supernatants were used for the measurements of the amounts and activities of the released PMN enzymes including PMN gelatinase (MMP-9), collagenase (MMP-8), serine proteases (elastase and cathepsin G), and lactate dehydrogenase (LDH). Both fluorescence microscopy and transmission electron microscopy showed that F. nucleatum, P. gingivalis and T. denticola were ingested by the PMNs in comparable numbers. However, measurements of the enzymes released from the triggered PMNs revealed major differences among the three species. High amount of elastase was released from the PMNs triggered by F. nucleatum, but not by P. gingivalis or T. denticola. The treatment of PMNs with P. gingivalis whole cells resulted in the release of gelatinase partly in the 82 kD active form, suggesting proteolytic activation of the degranulated 92 kD proMMP-9. The 82 kD active form of gelatinase was not detected upon triggering the PMNs with F. nucleatum and T. denticola. The PMN-bacteria interaction did not result in release of LDH from triggered PMNs indicating the proteinase release was not due to the PMN cell death. The results show that the susceptibilities of the 3 potentially periodontopathogenic microorganisms, F. nucleatum, P. gingivalis and T. denticola to phagocytic ingestion are not directly related to the amounts and activities of PMN enzymes released during the bacteria-PMN interactions. As PMN degranulation is considered as one of the major pathogenic mechanisms in periodontitis, the observed differences among the microorganisms may be important virulence characteristics of these species.

Membrane components of Treponema denticola trigger proteinase release from human polymorphonuclear leukocytes

Tissue destruction during periodontitis is believed to be primarily brought about by leukocyte proteinases. We postulate that oral spirochetes cause discharge of polymorphonuclear leukocyte (PMN) lysosomal enzymes. Effects of Treponema denticola 53-kDa outer membrane protein, lipopolysaccharide (LPS), and peptidoglycan on degranulation of matrix metalloproteinases (MMP)-8 (collagenase) and -9 (gelatinase), cathepsin G, and elastase by human peripheral blood PMNs were studied by specific enzyme assays and Western blot analysis. T. denticola 53-kDa kDa outer membrane protein was found to be a particularly efficient inducer of MMP-8 release. The induction was comparable with that of phorbol myristate acetate, a known inducer of PMN specific granule discharge. All of the treponemal substances, most notably the 53-kDa protein and LPS, induced release of MMP-9, a component of C-type granules. Both collagenase and gelatinase released from PMNs were mostly in active forms. Release of cathepsin G and elastase was also observed with the 53-kDa protein treatment. The other T. denticola substances did not induce release of these serine proteinases. Lactate dehydrogenase was not released from PMNs by the treatments, indicating that the degranulation was specific and not caused by toxic effects of the substances. This was confirmed by transmission electron microscopy of PMNs treated with the 53-kDa protein that showed rapid vacuole formation and cell shape changes but no disintegration of the cells. Thus, T. denticola may participate in the PMN-dependent extracellular matrix degradation during the course of periodontal inflammation by triggering the secretion and activation of matrix metalloproteinases.

Biochemical alterations in inflammatory periodontal diseases I. Poly (ADP-ribose) synthetase activity in gingiva and gingival fibroblasts from humans with periodontitis

Periodontal diseases are characterized in part by generation of oxygen free radicals, which can cause breaks in cellular DNA strands. Repair of damaged DNA is dependent upon the synthesis of poly (ADP-ribose)(PADPR) catalyzed by PADPR synthetase, an enzyme known to be activated by the broken ends of DNA strands. We measured the activities of PADPR synthetase and of PADPR glycohydrolase, which degrades PADPRS, in gingival biopsy specimens from 16 sites with adult periodontitis and 12 clinically healthy control sites. The results indicated that sites with periodontitis displayed markedly reduced PADPR synthetase activity compared with healthy control sites, whereas PADPR glycohydrolase activity was not changed. The mean specific activity of PADPR synthetase for the diseased specimens was one-sixth of that of the healthy specimens (p < 0.001). The PADPR synthetase activity was negatively correlated with the Gingival Index (rs = -0.60), pocket depth (rs = -0.70) and bleeding upon probing (rs = -0.72). Cultured fibroblasts derived from clinically characterized healthy and diseased gingival sites reflected similar patterns of enzyme activity. The mean specific activity of PADPR synthetase for the diseased-site cultures (n = 9) was 56 +/- 7% (p < 0.001) of the cultures from healthy control sites (n = 6). These results suggest that a reduced level of PADPR synthetase activity is associated with increased inflammation and periodontal destruction, and that the ability to synthesize PADPR is compromised in adult periodontitis.

Characterization of tetracycline and erythromycin resistance determinants in Treponema denticola

Treponema denticola isolates were evaluated for the presence of known tetracycline and erythromycin resistance determinants by Southern blot hybridization of whole-cell DNA and PCR assays. We examined all isolates available, which included 12 clinical and 4 American Type Culture Collection isolates. Two isolates carried the Tet B determinant, five isolates carried both the Tet B and Erm F determinants, seven isolates carried the Erm F determinant, and two did not carry any of the Tet or Erm determinants tested. Both the Tet B and Erm F determinants appeared to be associated with the chromosome. Neither of the two T. denticola donors tested could transfer the Tet B determinant, but three of four T. denticola tested transferred the Erm F determinant to an Enterococcus faecalis recipient. This extends the host range of both the tetB and ermF genes into the genus Treponema.

Comparison of a sonic and a manual toothbrush for efficacy in supragingival plaque removal and reduction of gingivitis

A new sonic electric toothbrush (Sonicare) and a traditional manual toothbrush were compared for efficacy in removing supragingival plaque and reducing gingival inflammation in a 12-week, single-blind clinical trial. 60 subjects with a gingival index (GI) of > 1.5 and no probing depths > 5 mm were randomly assigned to use either the manual or sonic brush, instructed in its use, and asked to brush each morning and evening for 2 minutes. Plaque scores were taken at baseline and at 1, 2, 4, and 12 weeks using the Turesky modification of the Quigley-Hein plaque index. Gingival inflammation was assessed by the GI, bleeding tendency score, presence or absence of bleeding on probing, volumetric measurements of gingival crevicular fluid (GCF), and aspartate aminotransferase (AST) levels in GCF. Repeated measures multivariate analyses of variance were used to detect time- and device-dependent differences for all clinical assessments between the 2 groups over the 5 visits. Both types of brush were effective in removing supragingival plaque. The sonic brush was statistically superior, on a percentage reduction basis, in removing supragingival plaque from the dentition taken as a whole (F-statistic; p = 0.012) and was particularly better in hard-to-reach areas such as posterior teeth (F-statistic; p = 0.003) and interproximal sites (F-statistic; p = 0.004). Both devices were equally effective in reducing gingival inflammation. The sonic brush exhibited less tendency to cause gingival abrasion than the manual brush (1 incident with sonic, 5 incidents with manual), confirming the safety of this product as an oral hygiene device.

Hyaluronan, a possible ligand mediating Treponema denticola binding to periodontal tissue

Binding of Treponema denticola ATCC 35405 to glycosaminoglycans, fibrinogen, type I collagen and porcine periodontal ligament epithelial cells was studied using an enzyme-linked immunosorbent assay. T. denticola bound to hyaluronan (hyaluronic acid) and its hexameric fragments. whereas little or no binding was detected to chondroitin-4-sulfate or dermatan sulfate proteoglycan. Binding of T. denticola to hyaluronan gradually increased during the 2-h incubation time. In contrast, binding to fibrinogen and type I collagen was more rapid, peaking within 5 min. T. denticola also bound to microbeads coated with hyaluronan and formed visible aggregates in solution. Pretreatment of the bacteria with hyaluronan or fibrinogen inhibited binding to hyaluronan. Gelatin, bovine serum albumin, chondroitin-4-sulfate, chondroitin-6-sulfate, heparin, dermatan sulfate, glucuronic acid, N-acetylglucosamine and N-acetyl-galactosamine did not inhibit binding. Binding was also inhibited by heating T. denticola and by pretreatment of the spirochetes with sodium periodate, phenylmethylsulfonyl fluoride, and p-chloromercurybenzoic acid. All these treatments also inhibited the chymotrypsin-like activity of T. denticola. Hyaluronan strongly inhibited binding of T. denticola to epithelial cells, whereas the other glycosaminoglycans and N-acetyl-glucosamine did not. The results show that T. denticola binds to hyaluronan, possibly by a mechanism involving the chymotrypsin-like surface protein of T. denticola.

Sequence analysis, expression, and binding activity of recombinant major outer sheath protein (Msp) of Treponema denticola

The gene encoding the major outer sheath protein (Msp) of the oral spirochete Treponema denticola ATCC 35405 was cloned, sequenced, and expressed in Escherichia coli. Preliminary sequence analysis showed that the 5' end of the msp gene was not present on the 5.5-kb cloned fragment described in a recent study (M. Haapasalo, K. H. Müller, V. J. Uitto, W. K. Leung, and B. C. McBride, Infect. Immun. 60:2058-2065,1992). The 5' end of msp was obtained by PCR amplification from a T. denticola genomic library, and an open reading frame of 1,629 bp was identified as the coding region for Msp by combining overlapping sequences. The deduced peptide consisted of 543 amino acids and had a molecular mass of 58,233 Da. The peptide had a typical prokaryotic signal sequence with a potential cleavage site for signal peptidase 1. Northern (RNA) blot analysis showing the msp transcript to be approximately 1.7 kb was consistent with the identification of a promoter consensus sequence located optimally upstream of msp and a transcription termination signal found downstream of the stop codon. The entire msp sequence was amplified from T. denticola genomic DNA and cloned in E. coli by using a tightly regulated T7 RNA polymerase vector system. Expression of Msp was toxic to E. coli when the entire msp gene was present. High levels of Msp were produced as inclusion bodies when the putative signal peptide sequence was deleted and replaced by a vector-encoded T7 peptide sequence. Recombinant Msp purified to homogeneity from a clone containing the full-length msp gene adhered to immobilized laminin and fibronectin but not to bovine serum albumin. Attachment of recombinant Msp was decreased in the presence of soluble substrate. Attachment of T. denticola to immobilized laminin and fibronectin was increased by pretreatment of the substrate with recombinant Msp. These studies lend further support to the hypothesis that Msp mediates the extracellular matrix binding activity of T. denticola.

Antagonistic effect of oral bacteria towards Treponema denticola

This study was designed to isolate oral bacteria exhibiting antagonism towards Treponema denticola and to characterize the inhibitory activity. Eleven bacterial isolates obtained from subgingival sites and identified as either Staphylococcus aureus or Streptococcus mutans were found to inhibit the growth of T. denticola. When the activity spectra of these isolates were analyzed, two additional periodontopathogens (Porphyromonas gingivalis and Prevotella intermedia) were found to be affected, whereas most gram-positive bacteria were not. Strains of S. aureus produce a bacteriocin-like inhibitory substance (heat stable and protease sensitive), whereas the inhibitory effect of S. mutans appears to be related to the production of lactic acid. The negative interactions reported in this paper may govern population shifts observed in subgingival sites.

Microbiological monitoring

If periodontal disease is due to a limited number of bacterial species, then continuous maximal plaque suppression is not the only possibility for prevention and therapy. Specific elimination or reduction of pathogenic bacteria from plaque becomes a valid alternative. Recent studies indicate that the elimination of certain putative pathogens is particularly difficult. New diagnostic methods should allow the choice of better suited procedures, make chosen procedures more effective (through better timing, dosage, selection of devices or drugs, increase of specificity, etc.) or lead to the elimination of unnecessary work (e.g., the treatment of non-susceptible sites or patients). The benefit of newly proposed tests depends on the possible impact of the obtained information on clinical decisions and on the consequences these decisions have for treatment. Thus, diagnostic methods and therapeutical options have to be evaluated together.

Characterization of new periodontal and endodontic isolates of spirochetes

Gas chromatographic analysis of cellular fatty acids (CFA), biochemical reactions, electrophoresis of soluble cellular proteins, as well as immunodiffusion were used to discriminate between 16 fresh spirochete isolates from periodontal and endodontic infections. CFA patterns were compared by the Hewlett Packard MIDI library to all available reference strains, and results of the biochemical tests were compared to VPI's records for treponemal strains. The electrophoretograms of soluble proteins of the fresh isolates were compared to those of previously well described strains of Treponema denticola, T. pectinovorum, T. vincentii, T. socranskii subsp. socranskii, T. socranskii subsp. paredis, T. socranskii subsp. buccale, and T. socranskii 04. Immunodiffusion was carried out by using adsorbed polyclonal rabbit antibodies to representative strains of the species mentioned. These methods separated most clinical strains from approved species strains, suggesting that new species had been isolated.

Dark field microscopy of the subgingival microflora in insulin-dependent diabetics

The subgingival microflora was assessed by means of dark field microscopy in 106 pockets of 47 subjects with long-term insulin-dependent diabetes mellitus (IDD). The microbiota of 55 healthy sulci (probing depth < 4 mm) and 51 periodontally diseased (probing depth > or = 4 and 6 mm) pockets were analyzed. The mean duration of the IDD of the diabetic subjects was 23.7 years (range from 10 to 41 years). The diabetic patients, aged 30-65 years, were under medical treatment at the III Department of Medicine, University of Helsinki Central Hospital, and at 2 clinics of the Helsinki Health Centre. Based upon their long-term medical records, 26 subjects were assessed to have poorly controlled insulin-dependent diabetes mellitus (PIDD) and 21 had controlled insulin-dependent diabetes (CIDD). The PIDD subjects exhibited higher mean blood glucose levels (12.9 +/- 4.6 mmol/l, mean +/- S.D.) than the CIDD subjects (7.9 +/- 3.6 mmol/l) (p < 0.001, t-test). The mean glycosylated hemoglobin HBA1 (HBA1c) levels were 11.2 +/- 4.6% (10.3 +/- 1.2%) and 8.8 +/- 1.8% (7.7 +/- 1.4%) for PIDD and CIDD subjects, respectively. These differences were statistically significant (p < 0.01 and p < 0.001, t-test). For each individual, site-specific recordings were made for plaque index and bleeding index scores, probing depth, loss of attachment and radiographic loss of alveolar bone. Dark field microscopy analysis of the presence of spirochetes, motile rods, cocci, non-motile rods, filaments and fusiforms was performed in the total of 106 pockets. According to the results of the dark field microscopy, the % of spirochetes and motile rods in the periodontally diseased pockets was significantly higher in the PIDD than in the CIDD subjects (9.2 +/- 13.4% and 10.8 +/- 14.3% versus 4.0 +/- 5.2% and 3.1 +/- 3.2%, p < 0.01 and p < 0.001, chi 2-test, respectively). Moreover, the PIDD subjects had lower mean %s of coccoid cells in periodontally diseased sites than the CIDD subjects (52.1 +/- 20.8% versus 60.7 +/- 9.0%, p < 0.001, chi 2-test).

Aspects of adherence of oral spirochetes

Oral spirochetes are present in the oral cavity in various numbers and forms and have been strongly implicated as playing a role in the etiology of periodontal disease. Because adherence to host tissues is a critical first step in establishing a bacterial infection, reports on the attachment of oral spirochetes to host tissues and matrix components were reviewed. The great bulk of the literature concerns Treponema denticola; however, where there is information regarding other oral spirochete species, it will be noted.

A comparison of the ability of foam swabs and toothbrushes to remove dental plaque: implications for nursing practice

This study aimed to assess the impact which the use of a toothbrush and the use of foam swabs had on the removal of dental plaque over a 6-day period. Three experiments were completed and duplicated using the author's mouth and one of these experiments was completed a third time on a volunteer's mouth. A plaque scoring system which quantified the amount of plaque on teeth in areas adjacent to periodontal tissue, and therefore capable of initiating inflammation, was used after plaque had been disclosed. Plaque at the gum/tooth margin (gingival crevice plaque) and plaque between teeth (approximal plaque) was measured. At the end of each 6-day period, which commenced with all tooth surfaces clean, the ability of the toothbrush to remove plaque was consistently better than that of swabs, and usually achieved complete visible plaque removal from all sites. In contrast, plaque remained in all sites which had been cleaned using foam swabs (after using a 'swabbing' or 'scrubbing' technique). However, it was possible to remove plaque from a number of gingival crevice sites with a swab when a varied 'any technique' was used on the visible disclosed plaque. The plaque in all approximal sites still remained after this technique. An experiment to measure the effect of using foam swabs on plaque which had been allowed to accumulate over a 6 day period produced similar results. The results from this study suggest that the success of a toothbrush in removing plaque is affected by user technique (total visible plaque removal was not achievable), and that foam swabs are not able to remove plaque from some 'sheltered' areas of teeth (total visible plaque removal was not achievable). The implications of these findings to nursing practice are discussed.

The 46-kilodalton-hemolysin gene from Treponema denticola encodes a novel hemolysin homologous to aminotransferases

The 46-kDa hemolysin produced by Treponema denticola may be involved in the etiology of periodontitis. In order to initiate a genetic analysis of the role of this protein in disease, its gene has been cloned. Synthetic oligonucleotides, designed on the basis of the previously reported amino-terminal amino acid sequence of the 45-kDa hemolysin, were used as primers in a PCR to amplify part of the hemolysin (hly) gene. This PCR product was then used to clone the entire hly gene from libraries of T. denticola genomic DNA. Constructs containing the entire cloned region on plasmids in Escherichia coli produced both hemolysis and hemoxidation activities either on sheep blood agar plates or in liquid assays. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) analysis revealed that the constructs synthesized a protein with molecular size of about 46 kDa which was reactive with anti-T. denticola hemolysin. Nucleotide sequence analysis indicated that the largest open reading frame could encode a protein with a calculated molecular size of 46.2 kDa. The first 31 amino acids encoded by this open reading frame were identical to the experimentally determined amino-terminal sequence of the 45-kDa hemolysin. These results indicate that the entire hly gene has been cloned. The deduced amino acid sequence of the T. denticola hly gene is homologous (23 to 37% identity) to those of proteins that are members of a family of pyridoxal-phosphate-dependent aminotransferases. This suggests that the 46-kDa hemolysin may be related to an aminotransferase and have a novel mechanism of hemolysis. However, the functional aspects of this relationship remain to be investigated.