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

Characterization of oral treponemes isolated from human periodontal pockets

A total of 90 clinical strains of oral treponemes was isolated from subgingival plaque in patients with periodontal disease. They were characterized by biochemical means as well as cell enzyme, protein analysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and DNA dot blot hybridization. Sixty strains were isolated on Medium 10 (M10), which was fundamentally serum-free. The remainder were isolated on serum-containing media. Isolates were divided into 6 groups according to their biochemical characteristics. Three of the 6 groups were asaccharolytic, and 2 of these 3 groups were Treponema denticola and "Treponema vincentii". The other 3 groups were saccharolytic and further divided into 9 subgroups. The analysis of cell enzyme, cell protein and dot blot hybridization with the DNA probe of Treponema socranskii indicated that all the saccharolytic groups were T. socranskii or closely related species. This study indicated that the newly characterized saccharolytic oral treponemes could be identified using M10 from the human periodontal pocket.

Population genetic analysis of oral treponemes by multilocus enzyme electrophoresis

Seventeen treponemes recently isolated from necrotic pulps, periodontal and periapical infections and 17 previously well characterized oral treponemal strains were analyzed by multilocus enzyme electrophoresis. Ten genetic loci were characterized on the basis of the electrophoretic mobilities of their enzymatic products. All loci were polymorphic. The average number of alleles per locus was 7.8. The genetic diversity among the electrophoretic types at each locus ranged from 0.624 to 0.836 with a mean genetic diversity per locus of 0.751. The 34 strains represented 34 electrophoretic types, constituting 6 main divisions (I-VI) separated at genetic distances greater than 0.75. Several of the previously characterized treponemes revealed multiple bands of enzyme activity at several loci, indicating that they were not pure. The characterized strains usually clustered within established species, whereas fresh clinical isolates overlapped species borders. There was a large genetic difference between some reference and clinical strains, indicating that the latter may contain undescribed species. Treponema socranskii and Treponema denticola strains clustered in distinct divisions (IV and V, respectively), with the exception of T. denticola strain FDC 51B2 and T. socranskii subsp. paredis strain VPI D46CPE1, both previously well described. This indicated that the taxonomic assignment of these 2 strains should be reconsidered.

Distribution of Porphyromonas gingivalis and Treponema denticola in human subgingival plaque at different periodontal pocket depths examined by immunohistochemical methods

Localization of Porphyromonas gingivalis and Treponema denticola in different areas of subgingival plaque from advanced adult periodontitis patients was studied immunohistochemically using sensitive immunogold-silver staining and immunoelectron microscopy. Fourteen periodontally diseased teeth were extracted without damaging the subgingival plaque, fixed, and embedded. The subgingival plaque samples were sectioned according to four different pocket depths (0-2 mm, 2-4 mm, 4-6 mm and > or = 6 mm). Serial thin sections were stained using specific antisera to P. gingivalis or T. denticola and then with secondary antibody labelled with colloidal-gold. Cells of both P. gingivalis and T. denticola were predominantly found in subgingival plaque located at depths of more than 4 mm in periodontal pockets. T. denticola cells were found in the surface layers of subgingival plaque, and P. gingivalis were predominant beneath them. However, in the deeper subgingival plaque, the coexistence of P. gingivalis and T. denticola was observed. The present findings suggest that P. gingivalis and T. denticola play important roles in the pathogenicity of periodontal disease and provide the useful information for elucidating the pattern of colonization of microorganisms in the periodontal pocket.

Cytopathic effects of Treponema denticola chymotrypsin-like proteinase on migrating and stratified epithelial cells

The effects of Treponema denticola and its outer membrane-bound chymotrypsin-like proteinase on periodontal ligament epithelial cell cultures at different stages of maturity were studied. In sparse cultures with migrating epithelial cells, large intracellular vacuoles were formed rapidly following exposure to live T. denticola. Treponemes showing structural damage were seen occasionally inside membrane-bound vesicles. Intensive membrane blebbing occurred in infected cells and continued for up to 48 h before the cell died. Blebbing could also be induced by a purified chymotrypsin-like proteinase of T. denticola. Cortical actin and alpha-actinin of the bacterium-treated cells showed disorganization, and pericellular fibronectin was degraded by both whole T. denticola and the isolated proteinase. Epithelial cells with well-formed lateral cell contacts appeared to be more resistant to the effects of T. denticola than migrating isolated cells. In multilayer epithelial cultures, adhesion of T. denticola and membrane blebbing were observed infrequently. There was no evidence of invasion of T. denticola into epithelial multilayers. However, immunogold electron microscopy showed rapid transport of T. denticola chymotrypsin-like proteinase into newly formed large intracellular vacuoles within the epithelial layers. These vacuoles were lined by membranes studded with ribosomes. T. denticola-treated epithelial multilayers had loose cell contacts, collapsed intercellular spaces, and increased permeability. Through its capacity to cause these unique cytopathic effects, the chymotrypsin-like proteinase of T. denticola has the potential to contribute to the initiation of periodontal disease.

A feasibility study on the use of direct light silver stain compared with dark field microscopy for differential counting of subgingival plaque

The purpose of the present study was to compare direct light microscopy using a silver stain, with dark field microscopy for differential counting of subgingival plaque samples from patients with periodontitis. The feasibility of using the staining method was assessed on subgingival plaque samples which were collected at 34 sites from patients with untreated adult periodontitis. Differential counts of plaque morphotypes assessed by both methods showed close agreement. The proportions of spirochaetes assessed by both methods were significantly associated with probing depth. The silver stain proved a simple, rapid and inexpensive method for differential counting of plaque composition. This method is suitable for possible use in general dental practice where smears could be made at the chair-side and allowed to dry ready for staining and counting at the dentist's convenience using a simple light microscope. A permanent record is also produced which could allow for comparison of samples from before and after treatment and could be used as an aid to patient motivation in suitable cases.

Cloning and expression of a neutral phosphatase gene from Treponema denticola

We have isolated and characterized a neutral phosphatase gene, phoN, from Treponema denticola ATCC 35405. The gene was isolated from a T. denticola clone bank constructed in the medium-copy-number plasmid vector pMCL19. Subcloning and nucleotide sequencing of the DNA insert from one phosphatase clone, pTph14, revealed that the activity corresponded to an open reading frame consisting of 1,027 bp coding for a 37.9-kDa protein. Hydrophobicity analysis indicated that the protein exhibits some hydrophobic regions. Indeed, partial purification of the phosphatase suggested that the enzyme was membrane associated both in T. denticola and in the Escherichia coli clone. The pH optimum of the enzyme, approximately pH 6.4, indicated that it corresponded to a neutral phosphatase activity from T. denticola. An examination of possible natural substrates for the enzyme suggested that this enzyme hydrolyzes nucleoside di- and triphosphates. Northern (RNA) blot analysis revealed that this phosphatase gene is not likely to be present in an operon structure.

Microbiological features of gingivitis in pubertal children

The subgingival microflora of 42 pubertal children (aged 12-15 years) and 18 young adults (aged 21-25 years) was investigated by anaerobic culture and phase contrast microscopy. Motile rods, spirochetes and Prevotella intermedia were elevated proportionately in pubertal children with gingivitis (median GI > or = 1); however, no statistically significant differences in enumerated organisms on selective media were observed between pubertal children and young adults. These organisms were positively correlated with the index of bleeding on probing and the gingival index of pubertal children. Pubertal children were divided into 3 distinct subject clusters according to the similarity of subgingival microbial features, and the subjects who were then selected for the gingivitis group were distributed into clusters 1 and 2. The proportions of motile rods, P. intermedia and Eikenella corrodens were significantly higher in cluster 2 than in cluster 1. These results suggest that these 2 species and motile rods which differentiated features of clusters, are useful for screening of high-risk subjects for worsening of inflammation.

Microscopic spirochete counts in untreated subjects with and without periodontal tissue destruction

The purpose of the study was to determine microscopically the %s of spirochetes at sites without periodontal destruction in subjects with destructive periodontal diseases (cases) and in subjects free of it (controls), who had not received professional prophylaxis. From a sample of 164 individuals aged between 30-44 years living in rural and urban areas of Tanzania, cases and controls were selected. Cases (n = 25) were selected who exhibited at least 3 teeth with pocket depth of > 5 mm. The controls (n = 28) had no pockets deeper than 3 mm. From each subject, 1 subgingival plaque sample was taken at the mid point of the lingual surface of 1 of the upper premolars which showed bleeding on probing but no calculus and no pockets. In addition, one subgingival sample was obtained from a pocket. Pockets contained the highest %s of spirochetes, which confirms earlier findings. A significant difference in % of spirochetes between cases and controls was found at non-destructive sites, indicating a host effect on the subgingival microflora. However, the spirochete counts at non-destructive sites did not provide a reliable measure to identify subjects with destructive periodontal disease.

Microbiota of rapidly progressive periodontitis lesions in association with clinical parameters

The microbial population in 73 rapidly progressive periodontitis (RPP) lesions in 10 young adults aged 25 to 35 years (5 males, 5 females) was studied in relation to the clinical parameters probing depth, bleeding on probing, and suppuration, which were recorded at the sampled sites. Porphyromonas gingivalis was found to predominate (26.7%) in 73 periodontal lesions with clinical probing depth > 6 mm, followed by Bacteroides forsythus (23.6%), and Prevotella intermedia (15.7%). The prevalence of P. gingivalis was 91.7%, Fusobacterium nucleatum, 90.4%; Streptococcus intermedius, 87.7%; and B. forsythus, 53.4%. Significant differences between bleeding index 0, 1, and 2 (P < 0.05) in frequency of detection were found for P. intermedia, Campylobacter concisus, Selenomonas sputigena, and Peptostreptococcus micros at bleeding sites and for Streptococcus sanguis, Actinobacillus actinomycetemcomitans, and B. forsythus (P < 0.001) at non-bleeding sites. Between suppurating and non-suppurating sites, significant differences (P < 0.05) in frequency of isolation were found for P. intermedia, Capnocytophaga ochracea, and A. actinomycetemcomitans at suppurating sites and for F. nucleatum at non-suppurating sites.

Effects of tetracycline-containing gel and a mixture of tetracycline and citric acid-containing gel on non-surgical periodontal therapy

The purpose of this study was to assess the clinical and microbiological effects of a newly developed root conditioning gel system containing tetracycline or a mixture of tetracycline and citric acid on non-surgical periodontal therapy. Sixty-four (64) single-rooted teeth with a probing depth of 4 to 6 mm were randomly subjected to one of the following four treatments; 1) root planing alone (RP group); 2) tetracycline-containing gel alone (TCG group); 3) root planing plus tetracycline-containing gel (RP + TCG group); or 4) root planing plus a mixture of tetracycline and citric acid-containing gel (RP + TC-CAG group). Probing depth, attachment level, and tooth mobility were measured and the presence of dental plaque and gingival inflammation was recorded at baseline and after 2, 4, 8, and 12 weeks. Subgingival plaque samples from each site were collected at the same visits and examined with phase contrast microscopy for proportions of motile rods and spirochetes. Plaque index, gingival sulcus bleeding index (SBI), probing depth, and attachment level decreased significantly in all groups compared to the baseline values (P < 0.05). A significant decrease in probing pocket depth was noted after 12 weeks in RP + TC-CAG group compared to the other groups (P < 0.05). Significantly more gain in attachment was detected in the RP + TC-CAG group compared to the TCG group (P < 0.05). Tooth mobility scores also decreased later in the study. A significant decrease in the proportion of motile rods was found primarily in the RP + TC-CAG group.(ABSTRACT TRUNCATED AT 250 WORDS)

A clinical study of an electronic constant force periodontal probe

Automated probing systems have been developed to provide a more precise method of evaluating periodontal pocket depths and attachment levels. The purpose of this study was to assess the clinical performance (reproducibility, time, and comfort) of a new electronic probe (E.P.) compared to the UNC 15 conventional probe (C.P.). Paired measurements 2 hours apart were performed by one examiner on 20 patients with moderate to advanced localized or generalized adult periodontitis. Both the E.P. and C.P. were used on each patient in a random manner. Overall reproducibility (+/- 1.5 mm) was: E.P. 94% (n = 1181); C.P. 96.5% (n = 1254); E.P./C.P. used interchangeably 82.4% (n = 830). In assessing the reproducibility of bleeding on probing, using the Wilcoxon matched pairs signed ranks test, only the mid-facial surface, when using the C.P. exhibited differences between measurements (P < 0.017). Paired t test revealed E.P. took significantly longer per exam (4 minutes, 46 seconds). Comfort levels, evaluated with a visual analog scale, were not significantly different between probes as shown by the Mann Whitney U test. The data suggest that, in general, there was no major significant difference in reproducibility measurements between the E.P. and the C.P. The E.P. took more time. Comfort levels were similar for both probes.

Influence of a single application of subgingival chlorhexidine gel or tetracycline paste on the clinical parameters of adult periodontitis patients

The clinical effects of subgingivally placed 1% chlorhexidine gel (w/w) and 40% tetracycline (w/w) paste in periodontal pockets of 22 adult periodontitis patients were studied. The 2 agents were applied following scaling and root planing in pockets exceeding 4 mm. The patients were randomly divided into 3 groups: (a) scaling and root planing (SCRP) only, the control group; (b) corsodyl gel+SCRP; (c) Tetracycline paste+SCRP. Gel or paste were gently applied using a syringe with a blunt needle until the selected pocket was overfilled. Evaluations were made of clinical parameters including the plaque index (PI), gingival index (GI), bleeding index (GI-S), probing pocket depths, probing attachment levels and position of the gingival margin. The results suggested that all the treatment modalities were effective in producing statistically significant improvements in clinical parameters. It was concluded that the conventional treatment modalities were essential in the treatment of periodontal diseases, but in view of the structure of the periodontal pocket and adjacent complex root surface, subgingival drug application in certain cases, might also provide adjunctive improvement.

Effect of rotary electric toothbrush versus manual toothbrush on decalcification during orthodontic treatment

The purpose of this study was to determine whether daily use of a rotary electric toothbrush (Rota-dent, Prodentec Corp., Batesville, Ark.) and a 0.05% sodium fluoride (NaF) rinse would significantly reduce decalcification when compared with manual toothbrushing only (control group) or manual toothbrushing and daily use of a NaF rinse (rinse group). All three groups used a standard fluoride toothpaste. Ninety consecutive adolescent patients who were to receive orthodontic treatment were placed into one of three groups according to age and sex criteria. Decalcification was evaluated single blind by two calibrated examiners on the facial surfaces of all permanent teeth before appliances were placed (baseline) and 3 months after appliances were removed (posttreatment). Data were analyzed by analysis of covariance with the dependent variable derived by subtracting the baseline decalcification scores from the posttreatment scores and using the baseline scores as the covariate. The results showed that although there were no significant differences between the three groups at baseline, the Rota-dent group showed significantly (p < 0.05) less posttreatment decalcification than either the control or rinse groups. In a separate analysis of first molars, the Rota-dent group again showed the least decalcification and the control group showed the most. These data suggest that twice daily use of the Rota-dent electric toothbrush with a standard fluoride toothpaste and once daily use of a 0.05% NaF rinse is more effective for preventing decalcification in adolescents during orthodontic treatment with fixed appliances than either conventional toothbrushing with a fluoride toothpaste, or similar toothbrushing and toothpaste with a once daily NaF rinse.

Diversity of cultivable and uncultivable oral spirochetes from a patient with severe destructive periodontitis

To determine the genetic diversity of cultivable and uncultivable spirochetes in the gingival crevice of a patient with severe periodontitis, partial 16S rRNA genes were cloned from PCR-amplified products of DNA and RNA extracted from a subgingival plaque sample. Approximately 500 bp were amplified in PCRs by using universally conserved primers with polylinker tails. Purified PCR products were cloned into Escherichia coli by using the plasmid vector pUC19. The resultant clone library was screened by colony hybridization with a radiolabeled, treponeme-specific oligonucleotide probe. The 16S rRNA inserts of 81 spirochetal clones were then sequenced by standard procedures. Sequences were compared with 16S rRNA sequences of 35 spirochetes, including the four known cultivable oral treponeme species. The analysis revealed an unexpected diversity of oral treponemes from a single patient. When 98% or greater sequence similarity was used as the definition of a species-level cluster, the clone sequences were found to represent 23 species. When 92% similarity was used as the definition, the clones fell into eight major groups, only two of which contained named species, Treponema vincentii and Treponema denticola, while Treponema pectinovorum and Treponema socranskii were not represented in any cluster. Seven of the 81 spirochetal clones were found to contain chimeric 16S rRNA sequences. In situ fluorescence hybridization with a fluorescein isothiocyanate-labeled oligonucleotide probe specific for one of the new species representing cluster 19 was used to identify cells of the target species directly in clinical samples.

Localized prepubertal periodontitis in a 5-year-old child: investigations and clinical observations over a 3-year period

A 5-year-old boy presented with persistent generalized gingival inflammation. Clinical and radiographic examination supplemented by immunological and microbiological investigation led to a diagnosis of localized prepubertal periodontitis. The child was subsequently monitored for 3 years and despite treatment there was continued bone loss related to his primary teeth. This case highlights the need for liaison between specialists in paediatric dentistry, periodontology, immunology and microbiology in order to diagnose prepubertal periodontitis and to establish a rational basis for treatment to prevent progression to juvenile periodontitis.

Eighteen-month evaluation of the effects of a 0.4% stannous fluoride gel on gingivitis in orthodontic patients

The purpose of this study was to determine whether conventional toothbrushing and twice daily use of a brush-on 0.4% stannous fluoride (SnF2) gel containing more than 90% available Sn2+ would be more effective for controlling plaque accumulation and gingivitis in the presence of orthodontic appliances than conventional toothbrushing alone. Consecutively treated adolescents who were to receive full-mouth fixed orthodontic appliances were assigned to one of two groups according to age and sex criteria. The first group (control, n = 35) used toothbrushing with a standard fluoride toothpaste, whereas the second group (treatment, n = 30) used toothbrushing supplemented with a 0.4% SnF2 gel used twice daily for the entire 18-month study period. Clinical assessments (Plaque Index, Gingival Index, bleeding tendency, and coronal staining) were made single blind before appliances were placed and 1, 3, 6, 9, 12, and 18 months after appliances were placed. Complete data were obtained for 32 control and 23 SnF2 gel subjects. The results indicated that the SnF2 gel group had significantly lower scores for plaque index (p < 0.01), gingival index (p < 0.001), and bleeding tendency (p < 0.001) at all examinations than did the control group. In the SnF2 group, one subject developed mild coronal staining, and two subjects developed moderate staining. We conclude that the use of a 0.4% SnF2 gel containing more than 90% available Sn2+ is an effective adjunct to mechanical tooth cleaning in preventing gingivitis in adolescents undergoing orthodontic treatment with fixed appliances.

Binding of hemin and congo red by oral hemolytic spirochetes

Colony-forming units or cells in suspension of oral anaerobic spirochetes (Treponema denticola, Treponema vincentii and Treponema socranskii) bind hemin and Congo red. Hemin or Congo red binds to a hydrophobic polypeptide receptor that is located in the outer membrane of the bacterial cells and it has a relative molecular mass of 47 kDa. These oral spirochetes also lyse sheep erythrocytes to produce beta-hemolytic zones around colony-forming units. The oral spirochetes may acquire iron for growth when they lyse erythrocytes and bind heme from which they may sequester and transport iron into the cells.

Involvement of treponemal surface-located protein and carbohydrate moieties in the attachment of Treponema denticola ATCC 33520 to cultured rat palatal epithelial cells

We studied the nature of attachment of Treponema denticola ATCC 33520 to a microscopically distinct population of rounded rat palatal epithelial cells. The motility of the freshly harvested spirochetes appeared not be a prerequisite for attachment. Treatment of T. denticola ATCC 3350 with proteinase-K, heat, glutaraldehyde, formaldehyde and periodate oxidation decreased the attachment to the rounded rat palatal epithelial cells, indicating the involvement of protein and carbohydrate moieties. Trypsin treatment had no effect on the attachment. The attachment of T. denticola ATCC 33520 was decreased after treatment with native non-immune rabbit serum, native polyclonal rabbit serum, D-mannose, N-acetyl-D-galactosamine and sialic acid. The results indicate that the attachment of T. denticola ATCC 33520 to rounded rat palatal epithelial cells is mediated by trypsin-resistant adhesin(s) of protein and carbohydrate nature, with affinity for D-mannose, N-acetyl-D-galactosamine and sialic acid.

Attachment of T. denticola strains ATCC 33520, ATCC 35405, B11 and Ny541 to a morphologically distinct population of rat palatal epithelial cells

In the present study an assay for the attachment of T. denticola to epithelial cells is described. An indirect immunohistochemical staining method, using two native polyclonal antisera, revealed dark-brown coloured spirochetes attached to rat palatal epithelial cell (RPE) monolayers. In addition, two morphologically distinct populations of RPE cells could be distinguished in the monolayers when using phase contrast microscopy. One minor population consisted of isolated rounded RPE cells that were lying on top of a confluent monolayer of flattened RPE cells. The rounded RPE cells were more receptive for the attachment of T. denticola than the flattened cells. The rounded RPE cells were evenly distributed over the monolayer, but the attachment of spirochetes to the rounded cells was greater at the edge than in the centre of the monolayers. The percentage of rounded RPE cells with attached spirochetes depended on the incubation time (optimum 6 h), temperature (optimum 37 degrees C) and pH (optimum 7.0). It is speculated that the attachment of T. denticola is a physical/chemical process of yet unknown nature and that differences in the number of microvilli and/or the amount of available receptors, between the two morphologically distinct cell types, accounts for the differences in the numbers of attached spirochetes.

The effect of subgingival debridement on periodontal disease parameters and the subgingival microbiota

The aim of the present investigation was to analyse the effect of subgingival scaling and root planing in subjects who prior to treatment exercised meticulous supragingival plaque control. 300 subjects were examined at baseline and after 1 and 2 years without treatment. After the year 2 examination, 62 subjects were randomly selected for therapy. They were given detailed instruction in proper self-performed toothcleaning measures and were carefully monitored during the subsequent 2 years. Following the year-4 examination, 2 quadrants, 1 maxillary and 1 mandibular in each subject, were randomly selected for additional therapy. The teeth in the selected quadrants were exposed to subgingival scaling and root planing. The subgingival therapy was repeated until a site no longer bled on gentle probing. This basic therapy was completed within a 2-month period. All subjects were re-examined after another 12-month interval. The examinations at year 4 and 5 included assessment of plaque, gingivitis, probing pocket depth and analysis of samples obtained from the subgingival microbiota at 134 selected sites. The findings from the present study demonstrated: (i) that subgingival scaling and root planing were effective in eliminating subgingival plaque and gingivitis; (ii) that professional therapy resulted in a pronounced reduction of probing depth at sites which at year 4 had a probing depth > 3 mm; (iii) that in non-scaled quadrants, the extension of self-performed plaque control resulted in a continued improvement of the periodontal conditions at sites which at year 4 were < 5 mm deep.

Effect of outer membrane of Treponema denticola on bone resorption

The effect of the outer membrane (outer sheath) of Treponema denticola on bone resorption was studied. Bone resorption was measured by the release of previously incorporated 45Ca from the shafts of the radii and ulnae of 19-day fetal rats. A treated-over-control ratio (T/C ratio) significantly greater than 1 indicated the stimulation of bone resorption by the test substance. The addition of outer membrane of T. denticola increased the release of 45Ca from the assay bones. The minimum concentrations required to yield significant 45Ca release from the assay bones were 15, 22 and 75 micrograms protein/ml for serovars a, b and c, respectively. These protein values corresponded to estimated lipopolysaccharide contents of 0.6, 0.8 and 2.8 micrograms/ml, based on 3-deoxy-2-manno-octulosonate analysis. Heat treatment of outer membrane (60 degrees for 30 min) did not change the effect on 45Ca release. Parathyroid hormone or prostaglandin E2, known to act synergistically with lipopolysaccharides in bone resorption, was also added to the assay system. Neither prostaglandin E2 at 10(-7) M nor parathyroid hormone at 40 ng/ml, by itself, increased 45Ca release. However, in the presence of 10 micrograms protein/ml of outer membrane of serovar b at 120 h, the T/C ratio was increased to 1.31 +/- 0.07 and 1.58 +/- 0.118, respectively. These results suggest that a lipopolysaccharide-like material is present in the outer membrane of T. denticola that may be responsible for bone resorption in the in vitro system.

Attachment of Treponema denticola strains to monolayers of epithelial cells of different origin

The attachment of 10 different Treponema denticola strains to monolayers of 4 types of epithelial cells derived from rat palatal epithelium, guinea pig ear, human buccal epithelium and human corneal epithelium was screened microscopically. Most T. denticola strains were able to attach to all four types of epithelial cells. The T. denticola strains seemed to attach better to epithelial cells derived from primary cultured material. The T. denticola strains showed different degrees of attachment. Scanning electron microscopy studies revealed that the attachment of T. denticola was not only tip-associated but occurred also at random points in close contact with microvilli of the epithelial cells. Attached spirochetes were non-uniformly distributed over the monolayers, indicating the presence of receptive subpopulations of epithelial cells in the monolayers.

Relationship of "bleeding on probing" and "gingival index bleeding" as clinical parameters of gingival inflammation

Bleeding on probing (BOP) and the gingival index have been used to clinically characterize the degree of gingival inflammation. It is, however, unclear to what extent these parameters correlate to each other and to probing pocket depth (PD). The purpose of this clinical study was to evaluate the association between BOP and GI bleeding (scores of 2 and 3), as well as the relationship of these variables to PD, in a group of patients presenting with naturally-occurring gingivitis. Based on screening examinations of 125 subjects with at least 20 teeth, no more than 4 sites with PD over 6 mm, a BOP frequency of 30% or greater, and no systemic condition that would influence the inflammatory response, were selected. 2 weeks after screening they were examined at 6 sites per tooth for plaque index, GI, PD and BOP. A standardized pressure sensitive probe (Florida Probe) with 20 g probing force was used for BOP and PD measurements. In this population, means of 40.9% (S.E. = 1.36) BOP sites and 35.3% (S.E. = 1.81) GI bleeding sites per patient were found. A total of 20,008 sites ranging in PD up to 5.9 mm were evaluated; however, the majority of sites (19,723, 98.6%) presented with < 4 mm PD. When sites were evaluated, BOP demonstrated a positive correlation with PD, whereas GI bleeding correlated with PD. For sites characterized by the absence of BOP as well as the absence of GI bleeding (scores 0 and 1), the highest % of agreement between the 2 indices (77.7%) was found in shallow sites (0.1-2 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

A stereomicroscopic and immunohistochemical study of vasculature in gingiva bleeding after probing

This study investigated the stereomicroscopic appearance of gingival sulcular surfaces and the histologic alterations of subepithelial vasculature of gingiva bleeding after probing. Sixty-four pairs of gingival biopsies from 49 patients were obtained and the results of stereomicroscopically visible vasculature were observed in half of the specimens. The number of biopsies showing that the vasculature of bleeding gingiva was significantly greater than those of non-bleeding gingiva. The immunohistochemical marker UEA-1 was used to identify endothelial cells on the vascular walls of 34 gingival biopsies from 15 patients. Following stereomicroscopic examination, tissue preparation with routine and UEA-1 stainings was performed. Volumetric and numerical analyses of vasculature in 6 divided portions of subepithelial connective tissue were measured. The results showed that significantly greater numbers of UEA-1 staining vessels were found within the apico-superficial portion of bleeding gingiva than those of non-bleeding gingiva. However, there was no specific correlation between the UEA-1 positive vessels within gingival tissue and stereomicroscopic visibility of vasculature on the surface appearance. It is suggested that increased vascularity in gingiva may be responsible for bleeding on clinical probing.

Nutritional interactions between two suspected periodontopathogens, Treponema denticola and Porphyromonas gingivalis

A mutual symbiotic enhancement of growth of Porphyromonas gingivalis and Treponema denticola is described in this report. Brain heart infusion broth supplemented with vitamin K did not support the individual growth of P. gingivalis or T. denticola. However, when inoculated as a mixture, both bacterial species did grow significantly. The growth-stimulating factors produced by P. gingivalis and T. denticola were dialyzable and heat stable and were further identified as isobutyric acid and succinic acid, respectively. Since some forms of periodontal disease are associated with the presence, in affected sites, of high numbers of P. gingivalis and spirochetes, it is suggested that the bacterial interaction described in this report might be of utmost importance in the initiation and progression of the disease.

Cloning and expression of the aspartate carbamoyltransferase gene from Treponema denticola

Treponema denticola seems to play a central role in the etiology of human periodontal disease. We have cloned an antigenic protein-coding sequence from T. denticola ATCC 33520. The protein-coding region was found to be a 3-kbp HindIII-HindIII fragment. The open reading frame consists of 1,426 bp and codes for a protein with an M(r) of 54,919. The deduced amino acid sequence showed 33.8% homology with that of the aspartate carbamoyltransferase of Escherichia coli. The gene products showed aspartate carbamoyltransferase activity.

Concentration of metronidazole in periodontal pockets after application of a metronidazole 25% dental gel

The metronidazole concentration was monitored in gingival crevicular fluid (GCF) of inflamed periodontal pockets after 1 application of a 25% gel. 12 patients with periodontal disease were included in the study. Metronidazole gel was applied with a syringe into the pockets of 10 teeth with probing depths > or = 5 mm. Samples of GCF were taken with Periopaper before application and 4, 8, 12, 24 and 36 h after application. At each time, samples from 2 teeth were pooled in order to obtain a sufficient amount of fluid for analysis. By means of a calibrated Periotron, the collected volume of GCF was measured. High-performance liquid chromatography was used to determine the amount of metronidazole. MIC50 for anaerobic periopathogens susceptible to metronidazole is below 1 microgram/ml. In this study, the concentration obtained was higher than 1 microgram/ml in all samples after 4 and 8 h, in 92% after 12 h, in 50% after 24 h and in 8% after 36 h. Thus, metronidazole concentrations in the pockets were generally above MIC50 for susceptible periopathogens 24 h after 1 application of a 25% metronidazole gel.

Characterization, cloning, and binding properties of the major 53-kilodalton Treponema denticola surface antigen

Treponema denticola surface proteins were studied for their biochemical and biological characteristics. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of detergent extracts of whole cells revealed a major protein of 53 kDa and a number of minor proteins. Antiserum raised against whole cells of T. denticola ATCC 35405 reacted with the 53-kDa protein and a 72-kDa protein but not with the other proteins. Immunoelectron microscopy with anti-53-kDa-protein antibodies showed that the 53-kDa protein is located on the surface of the cell. SDS-PAGE analysis of unheated samples indicated that the 53-kDa protein is the major component of oligomers with molecular masses ranging from 130 to 300 kDa. Western blot (immunoblot) analysis showed that the high-molecular-mass oligomers reacted with whole-cell antiserum and anti-53-kDa-protein antibody. The aggregates dissociated into their subunits after heating to 70 degrees C. Isoelectric focusing followed by SDS-PAGE indicated that the 53-kDa protein was separated into several forms with apparent pI values ranging from 8.0 to 5.5. The oligomeric forms were highly resistant to proteolysis by trypsin and proteinase K, whereas the monomeric proteins were readily digested. A clone expressing a 53-kDa antigen in Escherichia coli was isolated from a lambda ZAP II DNA library of T. denticola ATCC 35405. The recombinant protein had exactly the same molecular mass as the major 53-kDa T. denticola surface protein and reacted with antisera raised against this protein. The role of T. denticola ATCC 35405 surface proteins in attachment to laminin, fibronectin, gelatin, fibrinogen, and bovine serum albumin (BSA) was studied by a modified Western blot binding assay. Fibronectin, laminin, and fibrinogen attached to the 53-kDa surface protein of T. denticola as well as to a 72-kDa protein, whereas no attachment to gelatin or BSA was observed. Attachment could be inhibited by pretreating the blots with fibrinogen but not with gelatin or BSA. Our results suggest that the 53-kDa major surface protein of T. denticola may play a role in the attachment to host proteins and may thus be an important virulence determinant of this species.

Bacterial synergy of Treponema denticola and Porphyromonas gingivalis in a multinational population

Treponema denticola and Porphyromonas gingivalis have been associated with human adult severe periodontitis. In this study, we quantified these putative pathogens in subgingival plaque samples collected from 74 Fijians, 74 Colombians and 73 U.S. Americans stationed at the Multinational Force and Observers encampment in the Sinai Desert, Egypt. A contingency table of T. denticola and P. gingivalis frequency revealed a highly significant synergistic relationship. We discovered that the occurrence of T. denticola apparently requires the presence of P. gingivalis. This represents the first observation of a synergistic relationship between these putative oral pathogens associated with adult severe periodontal disease.

Treponema denticola and Porphyromonas gingivalis as prognostic markers following periodontal treatment

Subgingival plaque samples were collected from individuals with advanced periodontitis before and 3 to 11 weeks after scaling and root planing periodontal treatment. The plaque levels of Treponema denticola and Porphyromonas gingivalis antigens were measured before and after treatment by a quantitative immunoassay procedure using monoclonal antibodies specific for these oral bacteria. A decrease in mean levels of T. denticola (P less than .05) and P. gingivalis antigens (P less than .09) were observed following periodontal therapy. Improved health, as measured by a decrease in probing depth, was associated with a decrease in T. denticola antigen (P less than .05). These results suggest that the T. denticola levels of successfully treated sites decreased, while non-responding sites had levels of this microbial marker which were equal to or greater than the pre-treatment levels. These results provide additional evidence that T. denticola is associated with human adult severe periodontal disease, and can serve as a prognostic marker for disease recurrence.

Sulfhydryl-dependent attachment of Treponema denticola to laminin and other proteins

Attachment of Treponema denticola ATCC 35405 to laminin, a major basement membrane protein, and to other proteins was studied. Microdilution plates were coated with the proteins, and the attachment of T. denticola was measured by the enzyme-linked immunosorbent assay technique. Compared with bovine serum albumin (BSA), T. denticola had a high affinity to laminin, fibronectin, fibrinogen, and gelatin, as well as to type I and type IV collagens. Attachment to RGD peptide (Gly-Arg-Gly-Asp-Ser, the integrin recognition sequence) was only about 30% of that to laminin and was comparable to attachment to BSA. Tests with laminin fragments obtained through elastase digestion showed that the spirochetes attached well to an A-chain 140-kDa fragment involved in eukaryote cell attachment but did not attach to a 50-kDa fragment that includes the heparin binding site. Pretreatment of T. denticola with soluble laminin, fibronectin, gelatin, BSA, or fibrinogen had no effect on the attachment of the bacteria to laminin or fibronectin. A wide variety of compounds were tested for their possible inhibitory actions on the attachment. While most treatments of T. denticola ATCC 35405 had little or no effect on the attachment to proteins, sulfhydryl reagents p-chloromercuribenzoic acid (pCMBA) and oxidized glutathione inhibited the attachment by 70 to 99%, depending on the protein. When T. denticola was first allowed to attach to proteins, addition of pCMBA or oxidized glutathione could no longer reverse the attachment. Heat treatment of the spirochetes also markedly reduced the attachment to laminin, gelatin, and fibrinogen but not to BSA. Mixed glycosidase treatment of the spirochetes inhibited the attachment by 20 to 80%. None of the above treatments of the substrate proteins had any marked effect on the spirochete attachment. The results indicate that T. denticola has the capacity to bind to many different kinds of proteins by utilizing specific attachment mechanisms. The binding appears to involve protein SH groups and/or carbohydrate residues on the surface of T. denticola.

Associations between subgingival plaque bacterial morphotypes and clinical indices?

The aim of the present study was to evaluate possible associations between subgingival plaque bacterial morphotypes, as assessed by darkground microscopy, and clinical indices of routine adult chronic periodontitis. Clinical indices were plaque index (PlI), gingival index (GI), sulcus bleeding index (SBI), papilla bleeding index (PBI), attachment loss (AL), pocket depth (PD) and probeable pocket depth (PPD). Apical border plaque was sampled in vivo and after extraction to test whether direct or indirect sampling affected any such associations. Similarly, pocket depth and attachment loss were also assessed directly and indirectly on the same teeth, in vivo or after extraction. The influence of the type of index used to record inflammation (GI, SBI, PBI) was also assessed, as were the effects of the numbers of sampled subjects and the method of analysis, which comprised the use of transformed and untransformed data and of parametric and non-parametric tests. Data were collected in relation to the approximal surfaces of 44 teeth extracted from 22 adults (2 teeth each) and from 1 pair of contralateral upper anterior or premolar teeth in each of 100 adults, all which untreated routine chronic periodontitis. Selected subjects had greater than or equal to 4 mm probeable pocket depth and/or attachment loss, and radiographic evidence of bone loss in relation to 1 approximal surface on each of 1 pair of contralateral anterior or premolar teeth, or to 2 teeth scheduled for extraction. Plaque preparation and darkground microscopy were as described previously. Insignificant associations (p greater than 0.05) were demonstrated between supragingival plaque (PlI) and periodontal inflammation (GI, SBI, PBI) or destruction (PPD and AL), as well as between inflammation and attachment level. In contrast, significant moderate associations (r = 0.5-0.77) were demonstrated between each of the 3 morphotype groups; spirochaetes, other motiles and cocci. Spirochaetes showed a significant moderate (r = 0.5) positive association with pocket depth with a 2.43% mean increase of spirochaetes for each 1 mm increase of PPD. Although highly significant associations (r = 0.9) were demonstrable between the 3 inflammation indices (GI, SBI, PBI) themselves, only PBI showed significant positive associations (r = 0.3) with spirochaetes and other motiles. Also, PlI showed significant associations with each of the 4 morphotypes (r = 0.3-0.5). The heterogeneity of spirochaetes and other motiles as well as the multiplicity of possible aetiological microbial agents in plaque may have resulted in underestimated associations between subjects as well as undetectable association within a given mouth using only 4 morphotype groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Purification of phospholipase C by hydrophobic interaction affinity chromatography

A simple procedure is described for the purification of phosphatidylcholine-hydrolyzing phospholipase C(PLC). Lecithin, the substrate for PLC, was ligated hydrophobically to octyl-Sepharose in 2 M (NH4)2SO4. The washed lecithin-conjugated resin was then used to purify PLC from crude preparations by affinity chromatography. PLC binds to the lecithin moiety in the presence of Zn2+ and is eluted with an acidic buffer containing EDTA. PLC activity was recovered in the eluate. Both sodium dodecyl sulphate polyacrylamide gel electrophoresis and pI electrofocusing showed that the eluate contained a single monomeric protein with an apparent molecular mass of 66 kDa and a pI of 5.5.

Bleeding on probing as it relates to probing pressure and gingival health

The present study was designed to determine the threshold pressure value to be applied in provoking bleeding on probing (BOP) in clinically healthy gingival units. 12 female dental hygiene students volunteered for the study. They were selected on the basis of excellent oral hygiene standards, absence of probing depths greater than 3 mm and absence of caries or dental restorations on smooth and proximal tooth surfaces. Applying a probing force of 0.25, 0.5, 0.75 and 1.0 N in one of the 4 jaw quadrants, respectively, on 2 different occasions with an interval of 10 days, bleeding on probing was assessed. Oral hygiene and gingival conditions were determined using the criteria of the plaque control record and the gingival index. On the basis of the BOP values, obtained using the lowest probing force (0.25 N), the subjects were divided into 2 groups: group 1 ("minimal BOP" value) consisted of 6 subjects yielding practically no bleeding (mean BOP = 0.9%) at both examinations, while the subjects of group 2 ("low BOP" value) had slightly higher BOP% (mean BOP = 13.4%). Both groups showed significant increase in mean BOP% with increasing probing force (0.9%-36.1% in group 1 and 13.4%-47.0% in group 2). Regression analysis revealed an almost linear correlation and a high correlation coefficient between BOP% and probing force. The comparison of the regression lines of the 2 groups showed almost identical slope inclination. However, slight differences in slope inclination were found for different sites: approximal sites clearly yielded steeper regression lines than buccal/oral sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of acrylic strips containing amoxycillin with clavulanic acid for local drug delivery

The in vitro release of amoxycillin with clavulanic acid from acrylic strips at initial concentrations of 30, 40 and 50 per cent w/w was monitored using a double-beam ultraviolet spectrophotometer and compared with release of tetracycline hydrochloride. Highest levels of the antibacterial agents were released during the first 24 h period. Therapeutic levels of the drugs continued to be released during the subsequent 9 day period and were shown to be biologically active. Furthermore, for amoxycillin with clavulanic acid, an initial concentration of 40 per cent gave the highest level of release on day 10; while, for tetracycline, 50 per cent provided the highest level of release. Local application of 40 per cent amoxycillin with clavulanic acid incorporated into acrylic strips placed in periodontal pockets in patients with established periodontitis produced a marked change in the subgingival microflora as monitored by dark-field microscopy and cultural techniques. These changes in the subgingival flora were concomitant with elimination of bleeding on probing at the treated sites and were still evident 3 weeks after removal of the acrylic strips. The sensitivity of Bacteroides gingivalis (syn. Porphyromonas gingivalis) and Bacteroides intermedius (syn. Prevotella intermedia) isolated before and after treatment to amoxycillin with clavulanic acid remained unchanged.

Factors in virulence expression and their role in periodontal disease pathogenesis

The classic progression of the development of periodontitis with its associated formation of an inflammatory lesion is characterized by a highly reproducible microbiological progression of a Gram-positive microbiota to a highly pathogenic Gram-negative one. While this Gram-negative microbiota is estimated to consist of at least 300 different microbial species, it appears to consist of a very limited number of microbial species that are involved in the destruction of periodontal diseases. Among these "putative periodontopathic species" are members of the genera Porphyromonas, Bacteroides, Fusobacterium, Wolinella, Actinobacillus, Capnocytophaga, and Eikenella. While members of the genera Actinomyces and Streptococcus may not be directly involved in the microbial progression, these species do appear to be essential to the construction of the network of microbial species that comprise both the subgingival plaque matrix. The temporal fluctuation (emergence/disappearance) of members of this microbiota from the developing lesion appears to depend upon the physical interaction of the periodontal pocket inhabitants, as well as the utilization of the metabolic end-products of the respective species intimately involved in the disease progression. A concerted action of the end-products of prokaryotic metabolism and the destruction of host tissues through the action of a large number of excreted proteolytic enzymes from several of these periodontopathogens contribute directly to the periodontal disease process.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of complement by Treponema denticola

Oral spirochetes have been shown to be associated with periodontal diseases and are present in increased numbers in lesions of greater severity. In this study, the interaction of Treponema denticola with human complement, a major antibacterial defense system, was examined. For each of two strains of T. denticola, it was found that both the classical and alternative pathways of human complement were activated in human serum upon incubation at 37 degrees C. C3 fragments were deposited on the surface of this organism following complement activation; the fragments bound included both of the major C3-derived opsonic fragments C3b and iC3b. Under incubation conditions identical to those carried out for complement activation in serum, T. denticola failed to degrade purified, hemolytically-active C3, although it readily degraded inactivated C3. Thus, despite the documented proteolytic activity of this organism, complement activation and deposition of complement-derived opsonins may be important defense mechanisms in the control of infections with T. denticola.

A 2-year follow-up on the clinical and microbiological conditions of periodontium in teenagers

87 teenagers were included in a 2-year follow-up study on clinical and microbiological conditions of the periodontium. The clinical status was determined according to the Community Periodontal Index of Treatment Needs (CPITN) for subjects under 20 years of age. 59% of the subjects had at least 3 healthy sextants at the baseline and 68% at the 2-year examination. The microbiological conditions were assessed by using direct dark-field microscopy, and the culture of Actinobacillus actinomycetemcomitants (A.a.). Subgingival bacterial samples were taken, 2 for the microscopy and 2 for the culture, from the mesial surfaces of the first molars of each subject. The presence of gingival bleeding after probing was separately recorded from the 2 sites sampled for dark-field microscopy. No gingival bleeding at these 2 sites was found at the 2-year examination in 55% of those subjects who were non-bleeding at baseline, in 46% of the subjects initially with 1 bleeding site and in 13% of the subjects with both sites bleeding at baseline. 55% of the subjects with neither fusiforms, motile rods nor spirochetes at baseline maintained their healthy flora for 2 years. A.a. was recovered in 4 subjects at baseline and in 5 subjects 2 years later, in 3 of them at both examinations. Longer follow-up periods are needed to reveal the significance of the constant recovery of A.a. from the same subjects.

Topical chemotherapy in human periodontitis using a new controlled-release insert containing ofloxacin. I. Microbiological observation

The recognition that destructive periodontal diseases may be caused by specific microorganisms in periodontal pockets has led to an increased interest in and usage of antimicrobial agents in periodontal therapy. Recently, a new controlled-release insert containing ofloxacin, a synthetic antibiotic, has been developed. In this study, the controlled-release insert (PT-01) was microbiologically evaluated in combination with or without subgingival mechanical debridement. PT-01 was applied in the periodontal pockets of 27 patients with chronic periodontitis. Three sites with a deep probing pocket depth (greater than or equal to 5 mm) were randomly selected in different quadrants of each patient, and were assigned into three groups, i.e., PT-01 applied (T), placebo applied (P) and control sites (C). Periodontal treatments consisted of supragingival scaling with oral hygiene instruction for the first 2 weeks followed by root planing and subgingival scaling PT-01 was applied weekly on day 0 to 35, and the subgingival plaque samples from each site were collected on d 0, 14, 21 and 42. The dynamics of the subgingival microflora was investigated by dark field microscopy and by anaerobic and aerobic cultivation. In the supragingival scaling period, significant reduction in percentages of spirochetes and motile rods and significant increase of the percentage of coccoid cells were observed only at T sites. In addition, the total viable counts of bacteria, black-pigmented Bacteroides and Fusobacterium species were significantly reduced at T sites. After mechanical subgingival debridement, significant shifts in the proportion and reduction of the viable counts in the subgingival microflora were found at all sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Recolonization of the subgingival microflora after scaling and root planing in human periodontitis

The purpose of this study was to evaluate the recolonization patterns of the subgingival microflora of adult periodontitis patients after a single session of scaling and root planing. In each of eight patients, three clinically diseased sites were investigated microbiologically by darkfield microscopy and cultural analysis. After initial clinical and microbiological parameters were determined, each subject received a single session of scaling and root planing but no oral hygiene instructions. Clinical indices were measured and microbial parameters were reassessed 7, 21, and 60 days after treatment in a manner such that each of the test sites was sampled only once after treatment. Recolonization was evaluated by matching any single site with its own preoperative site. A significant improvement in probing depth was noted for up to 60 days after treatment, while the gingival index did not change markedly during the course of the study. The microbial composition of treated sites 7 days after scaling and root planing, as determined by both cultural and darkfield data, was similar to that of periodontally healthy sites. Differences between cultural and darkfield data became apparent at the 21 day sampling point. The darkfield data showed that the sites consisted of cocci with few spirochetes. Cultural data demonstrated that the majority of the cocci were anaerobic, namely Streptococcus intermedius, Veillonella parvula, and Peptostreptococcus micros. At 60 days, there was no significant variation in any of the parameters from pretreatment levels. The most prevalent anaerobic rods prior to and 60 days after therapy were Fusobacterium nucleatum, Bacteroides gingivalis, and B. intermedius.(ABSTRACT TRUNCATED AT 250 WORDS)

Darkground microscopy of subgingival plaque from the top to the bottom of the periodontal pocket

Part of the results of a study of subgingival plaque by darkground microscopy was used to investigate morphotype distribution at different levels within the periodontal pocket. Subgingival plaque was sampled at coronal, middle and apical levels from each of 28 approximal surfaces on 28 teeth extracted from 28 adults with untreated moderate to advanced periodontitis. Sample preparation and darkground microscopy were as described previously. The data recorded only the subgingival level at which the maximum count occurred for a given morphotype and subject. It was found that the maximum count of spirochaetes occurred most frequently at the apical level (p less than 0.05) and the maximum count of 'others' at the coronal level (p less than 0.05). Also, coccal counts showed a trend to increase the more apical the sample. Standardised darkground microscopy was able to show that the sampled subgingival level had a significant influence on plaque bacterial morphotype distribution, indicating the importance of accurate sampling of subgingival plaque at the most apical level.

Quantitative immunoassay of Treponema denticola serovar C in adult periodontitis

Murine monoclonal antibodies specific for Treponema denticola serovar C were produced and characterized in this study. An immunoassay was then developed by using these monoclonal antibodies, and the T. denticola serovar C antigen content of subgingival plaque was quantitated for samples taken from patients with periodontitis and healthy volunteers. The human subgingival plaque samples were grouped by severity of disease and pocket depth measurements at the collection site. The T. denticola serovar C content per milligram of subgingival plaque from deep pockets (greater than 6 mm) of patients with severe periodontitis was found to be twice that of samples collected from deep pockets (4 to 6 mm) of patients with moderate periodontitis or samples collected from healthy subjects (pocket depth, less than 4 mm).

Interaction of Treponema denticola TD-4, GM-1, and MS25 with human gingival fibroblasts

The adherence of Treponema denticola GM-1, TD-4, and MS25 to human gingival fibroblasts (HGFs) was studied to serve as an introduction to investigations into the interactions of these oral bacteria with human host cells. Under both aerobic (5% CO2) and anaerobic (85% N2 plus 10% H2 plus 5% CO2) environments, the interactions with the HGFs were such that strains GM-1 and MS25 were consistently more adherent than strain TD-4. Polyclonal antibodies to GM-1 inhibited GM-1 adherence by 70%, while MS25 and TD-4 showed differing degrees of cross-reactive inhibition, indicative of common but not identical epitopes on the surface of the three T. denticola strains. Pretreatment of the three strains with trypsin did not inhibit adherence; proteinase K did, however, inhibit this interaction by 80%. Trypsin pretreatment of the HGFs resulted in increases in adherence of 50 and 86% for GM-1 and MS25, respectively, while a decrease of 41% was noted for TD-4. Exposure of the T. denticola strains to sugars and lectin pretreatment of the HGFs implicated adherence mediation by mannose and galactose residues on the HGF surface. Periodate treatment of HGFs resulted in a 50% drop in adherence for GM-1 and MS25, but did not decrease that of TD-4. Addition of fetal bovine serum inhibited adherence of the three strains to differing degrees, with TD-4 being the most susceptible. Addition of purified fibronectin (100 micrograms/ml) resulted in greater than 50% inhibition in GM-1 and MS25 adherence, while a 25% increase occurred with TD-4. While strain differences were noted in some of the parameters studied, the results indicate two possibilities for T. denticola-HGF adherence: a lectinlike adhesin(s) on the T. denticola surface with affinity for galactose and mannose on the HGF surface, and a serum host factor(s) bridging T. denticola and HGFs.

Spirochaetes and granulocytes at sites involved in periodontal disease

Eighty-six men and 63 women with periodontitis participated in this investigation, at the start of which clinical indices were recorded and the pocket contents from one periodontally involved site for each patient were analysed. The numbers of spirochaetes, other motile microorganisms, non-motile filaments, rods or cocci and of granulocytes, monocytes and epithelial cells were determined. After non-surgical treatment 98 patients (P-group) were unsuccessfully and 51 (C-group) were successfully treated. At baseline the P-group had significantly higher numbers of spirochaetes (p = 0.0001) and polymorphonuclear leucocytes (p = 0.0256) than the C-group. The number of rods was statistically higher in the C-group (p = 0.0254). There was no significant difference between the groups with respect to the number of remaining teeth, plaque or calculus scores. Significantly higher values were found in the P-group for bleeding on probing (p = 0.0434), number of pockets greater than or equal to 5 mm (p = 0.0001), mean pocket depths (p = 0.0001), percentage bone loss per site (p = 0.0001) and the number of sites with greater than or equal to 20% bone loss on radiographs (p = 0.0001).