Metronidazole alone or with amoxicillin as adjuncts to non-surgical treatment of chronic periodontitis: a secondary analysis of microbiological results from a randomized clinical trial

AIM

To evaluate the changes occurring in the subgingival microbial profile of subjects with generalized chronic periodontitis (ChP) treated by scaling and root planing (SRP) alone or with metronidazole (MTZ) or MTZ + amoxicillin(AMX). A secondary aim was to examine a possible added effect of chlorhexidine(CHX) to these therapies.

METHODS

One hundred and eighteen subjects were randomly assigned to receive SRP-only or with MTZ [400 mg/thrice a day (TID)] or MTZ + AMX (500 mg/TID) for 14 days. Half of the subjects in each group rinsed with 0.12% CHX twice a day (BID) for 2 months. Nine subgingival plaque samples/subject were analysed by checkerboard DNA–DNA hybridization for 40 bacterial species at baseline, 3, 6 and 12 months post-therapy.

RESULTS

At 12 months, the antibiotic-treated groups harboured lower mean counts and proportions of key periodontal pathogens than the SRP group (p < 0.05). These benefits were observed at initially deep and shallow sites. Initial reductions in periodontal pathogens obtained with SRP partially rebound after 12 months. CHX rinsing enhanced the microbiological effects of the MTZ + AMX treatment in shallow sites.

CONCLUSION

The adjunctive use of MTZ and MTZ + AMX results in a greater reduction in the levels of periodontal pathogens in generalized ChP subjects compared to SRP alone.

Comparing clinical attachment level and pocket depth for predicting periodontal disease progression in healthy sites of patients with chronic periodontitis using multi-state Markov models

Aim

To understand degeneration of healthy sites and identify factors associated with disease progression in patients with chronic periodontitis.

Material and Methods

Data on healthy sites from 163 American and Swedish subjects were analysed using two-three-state (health, gingivitis, chronic periodontitis) Markov models based on bleeding on probing (BOP), and either clinical attachment level (CAL) + BOP or pocket depth (PD) + BOP.

Results

In 2 years, 10% (CAL + BOP) and 3% (PD + BOP) of healthy sites developed chronic periodontitis. On average, healthy sites remained healthy for 32 months before transiting in both models. Most transitions (87–97%) from health were to the gingivitis state. The expected duration of the gingivitis lesion was 4–5 months and sites recovered with a high probability (96–98%). Disease severity as measured by number of sites with CAL/PD > 4 mm at baseline and smoking, were associated with fast progression from health to chronic periodontitis within 6 months as were gingival redness in the PD + BOP model only. With age, the rate of disease progression to gingivitis decreased.

Conclusion

Transition probabilities for gingivitis and chronic periodontitis were higher with CAL + BOP than with PD + BOP. Smoking and disease severity were significant predictors for fast progression.

Multilevel analysis of bacterial counts from chronic periodontitis after root planing/scaling, surgery, and systemic and local antibiotics: 2-year results

AIM

To follow changes (over 2 years) in subgingival bacterial counts of five microbial complexes including health-related Actinomyces spp. in deeper pockets (≥5 mm) after periodontal treatments.

METHODS

EIGHT DIFFERENT TREATMENTS WERE STUDIED: (1) scaling+root planing (SRP); (2) periodontal surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole (MET); (3) SURG+locally delivered tetracycline (TET); (4) SURG; (5) AMOX+MET+TET; (6) AMOX+MET; (7) TET; and (8) SURG+AMOX+MET+TET. Antibiotics were given immediately following SRP. Subgingival plaque was collected mesiobuccally from each tooth, except third molars, from 176 subjects, completing the study, at baseline, 3, 6, 12, 18, and 24 months post-treatment and analysed for 40 different bacteria using checkerboard hybridization. A negative binomial (NB) generalized estimating equation (NB GEE) model was used to analyze count data and a logistic GEE was used for proportions.

RESULTS

We observed short-term beneficial changes in the composition of the red complex of up to 3 months by treating subjects with AMOX+MET+TET. Similar short-term improvements with the same treatment were observed for Tannerella forsythia and Treponema denticola of the red complex. SURG had also short-term beneficial effect on Porphyromonas gingivalis. No periodontal treatments applied to severely affected sites promoted the growth of Actinomyces. Smoking elevated counts of both the red and orange complex while bleeding on probing (BOP) and gingival redness were also predictors of more red complex counts. Comparatively similar findings were obtained by analyzing counts and by analyzing proportions.

CONCLUSIONS

Although short-term reductions in the counts of the red complex were observed in sites that were treated with AMOX+MET+TET, long-term significant effects were not observed with any of the eight treatments. Poor oral hygiene in patients with severe chronic periodontitis diminished the beneficial effects of treatment.

Effect of periodontal therapy on the subgingival microbiota over a 2-year monitoring period. I. Overall effect and kinetics of change

AIM

To examine the 2-year post-therapy kinetics of change in the composition of subgingival biofilms.

MATERIAL AND METHODS

In this study, 178 chronic periodontitis subjects were recruited and clinically monitored at baseline, 3, 6, 12, 18 and 24 months after therapy. All subjects received scaling and root planing and 156 one or more of periodontal surgery, systemically administered amoxicillin + metronidazole or local tetracycline at pockets ≥5 mm. Subgingival biofilm samples taken from each subject at each time point were analysed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The significance of changes in median species counts over time was sought using the Wilcoxon or Friedman tests and adjusted for multiple comparisons.

RESULTS

Mean counts were significantly reduced from baseline to 2 years for 30 of the 40 taxa. Marked reductions were observed for periodontal pathogens including Tannerella forsythia, Treponema denticola and Eubacterium nodatum. The kinetics of change differed from species to species. When data were subset according to baseline PD, patterns of change in the microbial profiles were generally similar.

CONCLUSION

Periodontal therapy leads to a rapid reduction in periodontal pathogens, followed by a slower reduction in other taxa that can be sustained for at least 2 years.

Microbiological basis for periodontal therapy

The search for the etiologic agents of periodontal diseases started in the Golden Era of medical bacteriology, when the etiologic agents of many bacterial infections were isolated and characterized. After the initial enthusiasm in establishing the infectious nature and the true agents of periodontal diseases, this concept was virtually ignored for the next four decades. Until the early 1970s treatment regimens based on the non-specific plaque hypothesis were directed towards a non-specific reduction in plaque amount. Later, the specific plaque hypothesis established the role of some microorganisms such as A. actinomycetemcomitans, P. gingivalis, T. forsythensis, T. denticola, P. intermedia and F. nucleatum in different forms of periodontal diseases. It was recently suggested that these suspected periodontal pathogens seem to not act alone and interactions between species, especially the balance between pathogenic and beneficial species affect both progression of disease and response of tissues to periodontal therapy. Nowadays it is well established that one of the goals of therapy is to control such periodontal pathogens. Among the most commonly used therapies to treat periodontal infections are scaling and root planing (SRP), supragingival plaque control and periodontal surgeries. Many studies confirmed the reduction of "red complex" species by SRP, and apically repositioned flap can lead to an additional beneficial effect in the subgingival microbiota by decreasing levels of "red" and "orange complexes" species. Furthermore, the level of plaque control maintained by the patients has been considered a crucial step in preventing recurrence of destructive periodontitis.

Multilevel analysis of clinical parameters in chronic periodontitis after root planing/scaling, surgery, and systemic and local antibiotics: 2-year results

AIM

Find the periodontal treatment that best maintained clinical results over time evaluated by changes in pocket depth (PD) and clinical attachment level (CAL).

METHODS

229 patients with chronic periodontitis from USA (n=134) and Sweden (n=95) were randomly assigned to eight groups receiving (1) scaling+root planing (SRP) alone or combined with (2) surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole (MET); (3) SURG+local tetracycline (TET); (4) SURG; (5) AMOX+MET+TET; (6) AMOX+MET; (7) TET; and (8) SURG+AMOX+MET+TET. Antibiotics were given immediately after SRP. Plaque, gingival redness, bleeding on probing, suppuration, PD, and CAL were recorded at baseline and after 3, 6, 12, 18, and 24 months. Treatment effects were evaluated by linear multilevel regression and logistic multilevel regression models. We considered only data from sites with a baseline PD of at least 5 mm of 187 patients completing the study.

RESULTS

Surgically treated patients experienced most CAL loss. Adjunctive therapy including SURG was most effective in reducing PD. Combining SURG with AMOX, MET, and TET gave significant clinical benefits. Past and current smoking habits were significant predictors of deeper PD. Only current smoking was a significant predictor of CAL loss. Bleeding, accumulation of plaque, gingival redness, and suppuration were significant predictors of further CAL loss and deeper PD.

CONCLUSIONS

Both surgical and non-surgical therapies can be used to arrest chronic periodontitis. SURG+AMOX+MET+TET gave best maintenance of clinical results.

Control of periodontal infections: a randomized controlled trial I. The primary outcome attachment gain and pocket depth reduction at treated sites

OBJECTIVE

To compare the treatment outcome of scaling and root planing (SRP) in combination with systemic antibiotics, local antibiotic therapy and/or periodontal surgery.

MATERIAL AND METHODS

One hundred and eighty-seven patients were assigned to eight groups treated by SRP plus none, one, two or three adjunctive treatments and monitored for 24 months in a randomized controlled clinical trial using a 2 × 2 × 2 factorial design. Systemic amoxicillin + metronidazole (SMA), local tetracycline delivery (LTC) and periodontal surgery (SURG) were evaluated as adjuncts. Changes in clinical attachment level (CAL) and probing pocket depth (PPD) were statistically evaluated by ancova of main effects.

RESULTS

Effects of adjunctive therapy to SRP were minimal at 3 months. Between 3 and 6 months PPD reduction occurred particularly in patients receiving periodontal surgery. After 6 months, both CAL gain and PPD reduction reached a plateau that was maintained at 24 months in all groups. The 24-month CAL gain was improved by SMA (0.50 mm) while PPD was reduced by SMA (0.51 mm) and SURG (0.36 mm). Smoking reduced CAL gain and PPD reduction.

CONCLUSION

Patients receiving adjunctive therapies generally exhibited improved CAL gain and/or PPD reduction when compared with the outcome of SRP alone. Only additive, not synergistic effects of the various adjunctive therapies were observed.

Comparison of microbial changes in early redeveloping biofilms on natural teeth and dentures

BACKGROUND

Surfaces and fluids can affect oral bacterial colonization. The aim of this study is to compare redeveloping biofilms on natural teeth and dentures.

METHODS

Supragingival plaque samples were taken from 55 dentate individuals and the denture teeth of 62 edentulous individuals before and after professional cleaning. Also, samples from seven "teeth" (samples included dentures) in randomly selected quadrants were collected after 1, 2, 4, and 7 days of no oral hygiene. Samples were analyzed using checkerboard DNA-DNA hybridization. Counts and proportions of 41 bacterial taxa were determined at each time point, and significant differences were determined using the Mann-Whitney U test. Ecological succession was determined using a modified moving window analysis.

RESULTS

Mean total DNA probe counts were similar precleaning but were higher in dentate individuals at all post-cleaning visits (P <0.01). Precleaning edentate biofilms had higher counts and proportions of Streptococcus mitis, Streptococcus oralis, and Streptococcus mutans, whereas dentate individuals had higher proportions of Tannerella forsythia, Selenomonas noxia, and Neisseria mucosa. By day 2, mean counts of all taxa were higher in natural teeth, and most remained higher at day 7 (P <0.01). Succession was more rapid and complex in dentate individuals. Both groups demonstrated increased proportions of S. mitis and S. oralis by day 1. N. mucosa, Veillonella parvula, and Eikenella corrodens increased in both groups, but later in samples from edentate individuals.

CONCLUSIONS

"Mature" natural and denture teeth biofilms have similar total numbers of bacteria but different species proportions. Post-cleaning biofilm redevelopment is more rapid and more complex on natural teeth than on denture teeth.

Microbiologic profile of endodontic infections from HIV- and HIV+ patients using multiple-displacement amplification and checkerboard DNA-DNA hybridization

OBJECTIVE

To compare the microbiota of endodontic infections in necrotic pulp from HIV-negative and HIV-positive subjects.

MATERIALS AND METHODS

Root canal samples from necrotic pulp were collected from 40 HIV- and 20 HIV+ subjects. Pulps were amplified using multiple displacement amplification (MDA). Then, checkerboard DNA-DNA hybridization was employed to assess the levels of 107 microbial taxa. The percentage of DNA probe count and the percentage of teeth colonized by each test species were investigated. Significant differences between groups regarding proportions of taxa and prevalence of the test species were sought using the Mann-Whitney test and the Chi-square analysis, respectively.

RESULTS

The most prevalent taxa detected were Dialister pneumosintes, Stenotrophomonas maltophilia, Streptococcus sobrinus, Corynebacterium diphteriae, and Helicobacter pylori among HIV- subjects and D. pneumosintes, Prevotella tannerae, Porphyromonas gingivalis, Parvimonas micra, Prevotella nigrescens, and Corynebacterium diphtheriae among HIV+ individuals. D. pneumosintes, C. diphtheria, and C. albicans were the most abundant species in the HIV- group, whereas the predominant taxa in HIV+ samples were P. tannerae, D. pneumosintes and Olsenella uli. P. tannerae, O. uli, Veilonella dispar, Bacteroides fragilis, and Actinomyces meyeri were significantly more abundant in HIV+ samples.

CONCLUSIONS

There were significant differences in the prevalence and proportions of specific microbial taxa between HIV- and HIV+ individuals. The root canal microbiota may represent a reservoir of important oral and medical pathogens, mainly in HIV+ individuals.

Impact of periodontal therapy on the subgingival microbiota of severe periodontitis: comparison between good responders and individuals with refractory periodontitis using the human oral microbe identification microarray

BACKGROUND

This study compares the changes to the subgingival microbiota of individuals with "refractory" periodontitis (RP) or treatable periodontitis (good responders [GR]) before and after periodontal therapy by using the Human Oral Microbe Identification Microarray (HOMIM) analysis.

METHODS

Individuals with chronic periodontitis were classified as RP (n = 17) based on mean attachment loss (AL) and/or >3 sites with AL ≥2.5 mm after scaling and root planing, surgery, and systemically administered amoxicillin and metronidazole or as GR (n = 30) based on mean attachment gain and no sites with AL ≥2.5 mm after treatment. Subgingival plaque samples were taken at baseline and 15 months after treatment and analyzed for the presence of 300 species by HOMIM analysis. Significant differences in taxa before and post-therapy were sought using the Wilcoxon test.

RESULTS

The majority of species evaluated decreased in prevalence in both groups after treatment; however, only a small subset of organisms was significantly affected. Species that increased or persisted in high frequency in RP but were significantly reduced in GR included Bacteroidetes sp., Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella spp., Tannerella forsythia, Dialister spp., Selenomonas spp., Catonella morbi, Eubacterium spp., Filifactor alocis, Parvimonas micra, Peptostreptococcus sp. OT113, Fusobacterium sp. OT203, Pseudoramibacter alactolyticus, Streptococcus intermedius or Streptococcus constellatus, and Shuttlesworthia satelles. In contrast, Capnocytophaga sputigena, Cardiobacterium hominis, Gemella haemolysans, Haemophilus parainfluenzae, Kingella oralis, Lautropia mirabilis, Neisseria elongata, Rothia dentocariosa, Streptococcus australis, and Veillonella spp. were more associated with therapeutic success.

CONCLUSION

Persistence of putative and novel periodontal pathogens, as well as low prevalence of beneficial species was associated with chronic refractory periodontitis.

Subgingival microbiota in adult Down syndrome periodontitis

BACKGROUND AND OBJECTIVE

The subgingival microbiota in Down syndrome and non-Down syndrome adults receiving periodic dental care was examined for 40 bacterial species using checkerboard DNA-DNA hybridization and the results were related to clinical periodontal attachment loss.

MATERIAL AND METHODS

A total of 44 Down syndrome, 66 non-Down syndrome mentally retarded and 83 mentally normal adults were clinically evaluated. This involved, for each subject, the removal of subgingival specimens from three interproximal sites on different teeth; all subgingival samples per subject were then pooled and assessed for the presence and levels of 40 bacterial species using species-specific whole-genomic DNA probes and checkerboard DNA-DNA hybridization. Significant group differences in species proportions averaged across subjects were evaluated using the Kruskal-Wallis test, and associations between subgingival species and mean subject attachment loss within Down syndrome and non-Down syndrome subject groups were quantified using Pearson correlation and multiple linear regression analysis.

RESULTS

Down syndrome subjects exhibited greater attachment loss than non-Down syndrome subjects (p=0.05). Most microbial species were present in Down syndrome subjects at levels similar to non-Down syndrome subjects, except for higher proportions of Selenomonas noxia, Propionibacterium acnes, Streptococcus gordonii, Streptococcus mitis and Streptococcus oralis in Down syndrome subjects compared with non-Down syndrome study subjects, higher proportions of Treponema socranskii in Down syndrome subjects compared with non-Down syndrome mentally retarded subjects, and higher proportions of Streptococcus constellatus in Down syndrome subjects compared with mentally normal subjects. Down syndrome adults classified with periodontitis revealed higher subgingival levels of T. socranskii than Down syndrome subjects with no periodontitis (p=0.02). Higher subgingival proportions of S. constellatus, Fusobacterium nucleatum ssp. nucleatum, S. noxia and Prevotella nigrescens showed significant positive correlations (r=0.35-0.42) and higher proportions of Actinomyces naeslundii II and Actinomyces odontolyticus showed negative correlations (r=-0.36 to -0.40), with increasing mean subject attachment loss in Down syndrome adults.

CONCLUSION

Individuals with Down syndrome show higher levels of some subgingival bacterial species and specific associations between certain subgingival bacterial species and loss of periodontal attachment. These findings are consistent with the notion that certain subgingival bacteria may contribute to the increased level of periodontal disease seen in Down syndrome individuals and raise the question as to the reason for increased colonization in Down syndrome.

Relationships among interleukin-6, tumor necrosis factor-α, adipokines, vitamin D, and chronic periodontitis

BACKGROUND

The aim of this study is to explore relationships among serum adipokines, vitamin D, and clinical and microbial parameters of chronic periodontitis before and after treatment.

METHODS

Weight, height, and smoking status were recorded for 56 patients with chronic periodontitis. Plaque, gingivitis, bleeding on probing, suppuration, probing depth, and clinical attachment level were measured at all teeth present. Subgingival biofilm samples from each tooth were analyzed for levels of 40 bacterial species using checkerboard DNA-DNA hybridization. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-α, adiponectin, leptin, resistin, and vitamin D were measured at baseline. Sample collection was then performed in a subset of the population 6 months after therapy (n = 17). Serum samples were analyzed using enzyme-linked immunosorbent assay and immunoassays. Differences in clinical, microbial, and serum factors among groups were sought using the Mann-Whitney U test. Correlations among factors were evaluated using regression analysis. Effects of therapy were sought using the Wilcoxon signed rank test.

RESULTS

There were positive correlations between adiponectin/vitamin D and between IL-6/leptin, negative correlations between IL-6/vitamin D and leptin/vitamin D, but no associations between serum analytes and clinical or microbial parameters. Sex and body mass index were associated with levels of adipokines. Periodontal therapy improved clinical and microbiologic parameters but did not influence the levels of serum analytes.

CONCLUSION

Adipokines and IL-6 levels were affected by sex and body mass index. Serum analytes were not influenced by periodontal therapy.

Effects of periodontal therapy on GCF cytokines in generalized aggressive periodontitis subjects

AIM

To examine changes in levels of gingival crevicular fluid (GCF) cytokines, after periodontal therapy of generalized aggressive periodontitis (GAgP).

MATERIALS AND METHODS

Twenty-five periodontally healthy and 24 GAgP subjects had periodontal clinical parameters measured and gingival crevicular fluid (GCF) samples collected from up to 14 sites/subject. GCF samples were analysed using multiplex bead immunoassay for: GM-CSF, IFN-γ, IL-10, IL-1β, IL-2, IL-6 and TNF-α. Aggressive periodontitis subjects were randomly assigned to either scaling and root planing (SRP) alone or SRP plus systemic amoxicillin (500 mg) and metronidazole (400 mg) 3 times a day for 14 days. Clinical parameters and GCF cytokines were re-measured 6 months after treatment. Differences over time were analysed using the Wilcoxon test and between groups using the Mann-Whitney test.

RESULTS

Significant reductions in GCF GM-CSF, IL-1β and the ratio IL-1β/IL-10 and increases in GCF IL-6 were detected after therapy. The mean change in GCF cytokines did not differ significantly between groups.

CONCLUSIONS

Periodontal therapy improved GCF cytokine profiles by lowering IL-1β and increasing IL-10 levels. The reduction in GCF GM-CSF after therapy implicates this cytokine in the pathogenesis of GAgP. There was no difference between therapies in changes of GCF cytokines.

Early microbial succession in redeveloping dental biofilms in periodontal health and disease

BACKGROUND AND OBJECTIVE

The development of dental biofilms after professional plaque removal is very rapid. However, it is not clear whether most bacterial species return at similar rates in periodontally healthy and periodontitis subjects or if there are differences in bacterial recolonization between supragingival and subgingival biofilms in periodontal health and disease.

MATERIAL AND METHODS

Supragingival and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects immediately after professional cleaning. Samples were taken again from seven teeth in randomly selected quadrants after 1, 2, 4 and 7 d of no oral hygiene and analyzed using checkerboard DNA-DNA hybridization. The percentage of DNA probe counts were averaged within subjects at each time-point. Ecological succession was determined using a modified moving-window analysis.

RESULTS

Succession in supragingival biofilms from subjects with periodontitis and from healthy individuals was similar. At 1 d, Streptococcus mitis and Neisseria mucosa showed increased proportions, followed by Capnocytophaga gingivalis, Eikenella corrodens, Veillonella parvula and Streptococcus oralis at 1-4 d. At 4-7 d, Campylobacter rectus, Campylobacter showae, Prevotella melaninogenica and Prevotella nigrescens became elevated. Subgingival plaque redevelopment was slower and very different from supragingival plaque redevelopment. Increased proportions were first observed for S. mitis, followed by V. parvula and C. gingivalis and, at 7 d, by Capnocytophaga sputigena and P. nigrescens. No significant increase in the proportions of periodontal pathogens was observed in any of the clinical groups or locations.

CONCLUSION

There is a defined order in bacterial species succession in early supragingival and subgingival biofilm redevelopment after professional cleaning.

Microbial shifts during dental biofilm re-development in the absence of oral hygiene in periodontal health and disease

AIM

To monitor microbial shifts during dental biofilm re-development.

MATERIALS AND METHODS

Supra- and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects at baseline and immediately after tooth cleaning. Samples were taken again from seven teeth in randomly selected quadrants during 1, 2, 4 and 7 days of no oral hygiene. Samples were analysed using checkerboard DNA-DNA hybridization. Species counts were averaged within subjects at each time point. Significant differences in the counts between healthy and periodontitis subjects were determined using the Mann-Whitney test.

RESULTS

The total supra- and subgingival counts were significantly higher in periodontitis on entry and reached or exceeded the baseline values after day 2. Supragingival counts of Veillonella parvula, Fusobacterium nucleatum ss vincentii and Neisseria mucosa increased from 2 to 7 days. Subgingival counts were greater for Actinomyces, green and orange complex species. Significant differences between groups in supragingival counts occurred for 17 of 41 species at entry, 0 at day 7; for subgingival plaque, these values were 39/41 taxa at entry, 17/41 at day 7.

CONCLUSIONS

Supragingival plaque re-development was similar in periodontitis and health, but subgingival species recolonization was more marked in periodontitis.

RNA-oligonucleotide quantification technique (ROQT) for the enumeration of uncultivated bacterial species in subgingival biofilms

Approximately 35% of the species present in subgingival biofilms are as yet uncultivated, so their role in periodontal pathogenesis is unknown. The aim of the present study was to develop a high throughput method to quantify a wide range of cultivated and uncultivated taxa in subgingival biofilm samples associated with periodontal disease or health. Oligonucleotides targeting the 16S ribosomal DNA gene were designed, synthesized and labeled with digoxigenin. These probes were hybridized with the total nucleic acids of pure cultures or subgingival biofilm samples. Target species included cultivated taxa associated with periodontal health and disease, as well as uncultivated species, such as TM7 sp. OT 346, Mitsuokella sp. OT 131 and Desulfobulbus sp. OT 041. Sensitivity and specificity of the probes were determined. A Universal probe was used to assess total bacterial load. Sequences complementary to the probes were used as standards for quantification. Chemiluminescent signals were visualized after film exposure or using a CCD camera. In a pilot clinical study, 266 subgingival plaque samples from eight periodontally healthy people and 11 patients with periodontitis were examined. Probes were specific and sensitivity reached 10(4) cells. Fusobacterium nucleatum ss. polymorphum and Actinomyces gerencseriae were the most abundant cultivated taxa in clinical samples. Among uncultivated/unrecognized species, Mitsuokella sp. OT 131 and Prevotella sp. OT 306 were the most numerous. Porphyromonas gingivalis and Desulfobulbus sp. OT 041 were only detected in patients with periodontitis. Direct hybridization of total nucleic acids using oligonucleotide probes permitted the quantification of multiple cultivated and uncultivated taxa in mixed species biofilm samples.

Microbiota of deciduous endodontic infections analysed by MDA and Checkerboard DNA-DNA hybridization

AIMS

To evaluate the microbiota of endodontic infections in deciduous teeth by Checkerboard DNA-DNA hybridization after uniform amplification of DNA in samples by multiple displacement amplification (MDA).

METHODOLOGY

Forty samples from the root canal system of deciduous teeth exhibiting pulp necrosis with or without radiographically detectable periradicular/interradicular bone resorption were collected and 32 were analysed, with three individuals contributing two samples; these were MDA-amplified and analysed by Checkerboard DNA-DNA hybridization for levels of 83 bacterial taxa. Two outcome measures were used: the percentage of teeth colonized by each species and the mean proportion of each bacterial taxon present across all samples.

RESULTS

The mean amount of DNA in the samples prior to amplification was 5.2 (±4.7) ng and 6.1 (±2.3) μg after MDA. The mean number of species detected per sample was 19 (±4) (range: 3-66) to the nearest whole number. The most prevalent taxa were Prevotella intermedia (96.9%), Neisseria mucosa (65.6%), Prevotella nigrescens (56.2%) and Tannerella forsythia (56.2%). Aggregatibacter (Haemophilus) aphrophilus and Helicobacter pylori were not detected. P. intermedia (10%), Prevotella tannerae (7%) and Prevotella nigrescens (4.3%) presented the highest mean proportions of the target species averaged across the positive samples.

CONCLUSION

Root canals of infected deciduous teeth had a diverse bacterial population. Prevotella sp. were commonly found with P. intermedia, Prevotella tannerae and Prevotella nigrescens amongst the most prominent species detected.

Relationships between subgingival microbiota and GCF biomarkers in generalized aggressive periodontitis

AIM

To examine relationships between subgingival biofilm composition and levels of gingival crevicular fluid (GCF) cytokines in periodontal health and generalized aggressive periodontitis (GAP).

MATERIALS AND METHODS

Periodontal parameters were measured in 25 periodontally healthy and 31 GAP subjects. Subgingival plaque and GCF samples were obtained from 14 sites from each subject. Forty subgingival taxa were quantified using checkerboard DNA-DNA hybridization and the concentrations of eight GCF cytokines were measured using Luminex. Cluster analysis was used to define sites with similar subgingival microbiotas in each clinical group. Significance of differences in clinical, microbiological and immunological parameters among clusters was determined using the Kruskal-Wallis test.

RESULTS

GAP subjects had statistically significantly higher GCF levels of interleukin-1beta (IL-1beta) (p<0.001), granulocyte-macrophage colony-stimulating factor (GM-CSF) (p<0.01) and IL-1beta/IL-10 ratio (p<0.001) and higher proportions of Red and Orange complex species than periodontally healthy subjects. There were no statistically significant differences in the mean proportion of cytokines among clusters in the periodontally healthy subjects, while the ratio IL-1beta/IL-10 (p<0.05) differed significantly among clusters in the aggressive periodontitis group.

CONCLUSIONS

Different subgingival biofilm profiles are associated with distinct patterns of GCF cytokine expression. Aggressive periodontitis subjects were characterized by a higher IL-1beta/IL-10 ratio than periodontally healthy subjects, suggesting an imbalance between pro- and anti-inflammatory cytokines in aggressive periodontitis.

Survival of Dicor glass-ceramic dental restorations over 20 years: Part IV. The effects of combinations of variables

PURPOSE

Previous studies have shown the relationship of individual clinical variables to the survival of Dicor (Corning Glass Works) restorations. The purpose of the present investigation was to examine the effect of combinations of these variables on the intraoral survival of Dicor restorations.

MATERIALS AND METHODS

Dicor glass-ceramic restorations (n=1,444) were placed in 417 adult patients. Failure was defined as a restoration that required remake because of material fracture. The survival of restorations with different combinations of variables that were each individually associated with survival was described using Kaplan-Meier survivor functions. The statistical significance of differences in survival between different combinations of specific predictor variables was examined using the proportional hazards model.

RESULTS

Kaplan-Meier survival analysis indicated that significantly worse survival rates were found for restorations that included combinations of molar teeth, a dentin core, and a glass-ionomer luting agent; molar teeth, a dentin core, and a resin luting agent; and single-rooted teeth, a dentin core, and a glass-ionomer luting agent than for any other combinations tested. The Cox proportional hazards model described a hazard ratio of 3.37 (95% confidence interval [CI]: 2.23 to 5.08) for molar teeth (versus single-rooted teeth), 2.65 (95% CI: 1.44 to 4.87) for dentin core (versus gold core), 2.35 (95% CI: 1.58 to 3.51) for men (versus women), and 1.72 (95% CI: 1.13 to 2.60) for glass-ionomer luting agent (versus resin) after adjusting for the other variables in the model.

CONCLUSION

Factors beyond individual restoration design impact the survival of Dicor glass-ceramic. These include sex, tooth position, and restorations luted to gold core foundation bases.

Comparisons of subgingival microbial profiles of refractory periodontitis, severe periodontitis, and periodontal health using the human oral microbe identification microarray

BACKGROUND

This study compared the subgingival microbiota of subjects with refractory periodontitis (RP) to those in subjects with treatable periodontitis (GRs = good responders) or periodontal health (PH) using the Human Oral Microbe Identification Microarray (HOMIM).

METHODS

At baseline, subgingival plaque samples were taken from 47 subjects with periodontitis and 20 individuals with PH and analyzed for the presence of 300 species by HOMIM. The subjects with periodontitis were classified as having RP (n = 17) based on mean attachment loss (AL) and/or more than three sites with AL >or=2.5 mm after scaling and root planing, surgery, and systemically administered amoxicillin and metronidazole or as GRs (n = 30) based on mean attachment gain and no sites with AL >or=2.5 mm after treatment. Significant differences in taxa among the groups were sought using the Kruskal-Wallis and chi(2) tests.

RESULTS

More species were detected in patients with disease (GR or RP) than in those without disease (PH). Subjects with RP were distinguished from GRs or those with PH by a significantly higher frequency of putative periodontal pathogens, such as Parvimonas micra (previously Peptostreptococcus micros or Micromonas micros), Campylobacter gracilis, Eubacterium nodatum, Selenomonas noxia, Tannerella forsythia (previously T. forsythensis), Porphyromonas gingivalis, Prevotella spp., Treponema spp., and Eikenella corrodens, as well as unusual species (Pseudoramibacter alactolyticus, TM7 spp. oral taxon [OT] 346/356, Bacteroidetes sp. OT 272/274, Solobacterium moorei, Desulfobulbus sp. OT 041, Brevundimonas diminuta, Sphaerocytophaga sp. OT 337, Shuttleworthia satelles, Filifactor alocis, Dialister invisus/pneumosintes, Granulicatella adiacens, Mogibacterium timidum, Veillonella atypica, Mycoplasma salivarium, Synergistes sp. cluster II, and Acidaminococcaceae [G-1] sp. OT 132/150/155/148/135) (P <0.05). Species that were more prevalent in subjects with PH than in patients with periodontitis included Actinomyces sp. OT 170, Actinomyces spp. cluster I, Capnocytophaga sputigena, Cardiobacterium hominis, Haemophilus parainfluenzae, Lautropia mirabilis, Propionibacterium propionicum, Rothia dentocariosa/mucilaginosa, and Streptococcus sanguinis (P <0.05).

CONCLUSION

As determined by HOMIM, patients with RP presented a distinct microbial profile compared to patients in the GR and PH groups.

Factors affecting human supragingival biofilm composition. I. Plaque mass

BACKGROUND AND OBJECTIVE

Little is known about the factors that affect the microbial composition of supragingival biofilms. This study was designed to examine the relationship between total DNA probe counts of supragingival biofilm samples, clinical parameters and supragingival biofilm composition.

MATERIAL AND METHODS

Supragingival plaque samples were taken from 187 systemically healthy adult subjects (n = 4745 samples). All samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The relationship between total DNA probe counts and microbial composition was examined by subsetting the data into 10 groups based on 10 percentile increments of the total DNA probe counts. Differences among groups in terms of species counts and proportions were sought, as well as relationships of total plaque DNA probe count and clinical parameters.

RESULTS

There was a wide distribution in mean total DNA probe counts among the 187 subjects. With increasing total plaque levels there was a change in the proportions of individual species and microbial complexes. 'Small plaques' were characterized by high proportions of species in the yellow, orange, purple and 'other' complexes; plaques of moderate mass were characterized by high proportions of Actinomyces and purple complex species, while 'large plaques' exhibited increased proportions of green and orange complex species. Measures of gingival inflammation, pocket depth and recession were significantly positively associated with total DNA probe counts. Increased plaque numbers were related to increased pocket depth irrespective of presence or absence of gingival inflammation.

CONCLUSION

The proportions of individual species and microbial complexes in supragingival biofilms are influenced by the total numbers of organisms in the biofilm.

Application of the checkerboard immunoblotting technique to the quantification of host biomarkers in gingival crevicular fluid

BACKGROUND

The aim of this study was to describe the development and validation of the checkerboard immunoblotting (CBIB) technique for the high-throughput quantification of multiple inflammatory mediators in gingival crevicular fluid (GCF) samples.

METHODS

Monoclonal antibodies were used to bind GCF interleukin (IL)-1beta and -8 and matrix metalloproteinase (MMP)-8 to the surface of membranes. Biotinylated antibodies were used to detect bound antigens in a checkerboard format. Signals were developed using chemiluminescence, captured on film, and quantified using software for array analysis. The assay was tested for potential cross-reactions among the three pairs of antibodies. Eleven CBIBs were processed to determine the analytical sensitivity of the assay. Forty GCF samples were analyzed using CBIB and enzyme-linked immunosorbent assay (ELISA) in parallel, and the significance of the correlations among the results was tested using the Pearson correlation coefficient. Nine hundred thirty-one GCF samples were collected from 20 periodontally healthy subjects and 20 periodontitis subjects and analyzed using CBIB to test the assay's sensitivity and dynamic ranges using clinical samples.

RESULTS

The CBIB was capable of distinguishing among the three analytes. The sensitivity and dynamic ranges of the assay were suitable for the detection of the three targets in the majority of GCF samples. There were highly statistically significant (P <0.0001) positive correlations between CBIB and ELISA data for all three biomarkers. The periodontitis subjects had statistically significantly higher mean levels of IL-1beta and -8 compared to healthy subjects.

CONCLUSION

The CBIB technique is a sensitive and specific assay for the high-throughput quantification of MMP-8 and IL-8 and -1beta in GCF.

Comparison between polymerase chain reaction-based and checkerboard DNA hybridization techniques for microbial assessment of subgingival plaque samples

AIM

To compare polymerase chain reaction (PCR) with subsequent reverse hybridization (micro-IDent test) and checkerboard DNA-DNA hybridization for the identification of 13 bacterial species in subgingival plaque samples.

MATERIAL AND METHODS

Subgingival plaque samples were taken using paper points and curettes from two sites each with pocket depth <4, 4-6 and >6 mm at baseline and 3 months in 25 periodontitis subjects and two sites in 25 periodontally healthy subjects. Samples were analysed for their content of 13 bacterial species using both assays. Similarities for each species between techniques were determined using regression analysis. Differences between health and periodontitis were determined using the Mann-Whitney test.

RESULTS

Three hundred and fifty samples were evaluated using both techniques. Regression analysis indicated that 10/13 test species showed significant positive correlations between the counts determined by checkerboard analysis and levels determined by the PCR-based test after adjusting for 13 comparisons. The highest rank correlations of 0.58, 0.49 and 0.46 were seen for Treponema denticola, Fusobacterium nucleatum and Eubacterium nodatum, respectively (p<0.0001). Both tests could distinguish samples from healthy and periodontitis subjects.

CONCLUSION

Detection patterns of 10/13 test species in subgingival plaque samples from periodontitis and healthy subjects were similar using the two molecular techniques.

Salivary cytokine levels in subjects with chronic periodontitis and in periodontally healthy individuals: a cross-sectional study

BACKGROUND AND OBJECTIVE

Saliva has been proposed as a noninvasive diagnostic fluid that could be used in the diagnosis of oral and systemic diseases. The levels of salivary biomarkers, such as cytokines, could potentially be used as a surrogate to distinguish periodontally healthy individuals from subjects with periodontitis. Therefore, the goal of the present investigation was to determine if the levels of 10 different cytokines in saliva differed between a group of periodontally healthy individuals and a group of subjects with periodontitis. Correlations between the concentrations of these 10 cytokines and clinical parameters of periodontal disease were also examined.

MATERIAL AND METHODS

In this cross-sectional study, 74 subjects with chronic periodontitis and 44 periodontally healthy individuals were periodontally examined and had the levels of granulocyte-macrophage colony-stimulating factor, interleukin-1beta, interleukin-2, interleukin-4, interleukin-5, interleukin-6, interleukin-8, interleukin-10, interferon-gamma and tumor necrosis factor-alpha measured in whole saliva using a multiplexed bead immunoassay (Luminex). Significance of statistical differences in the levels of salivary cytokines between groups was determined using nonparametric analysis of covariance, adjusting for age and smoking status. The Spearman rank correlation coefficient was used to explore associations between the mean levels of salivary cytokines and mean clinical parameters.

RESULTS

There were no statistically significant differences between groups for any of the cytokines. There were weak, statistically significant positive associations between salivary interleukin-8 and pocket depth (r(s) = 0.2, p < 0.05) and bleeding on probing (r(s) = 0.2, p < 0.05), and weak negative correlations between salivary interleukin-10 and attachment level (r(s) = -0.2, p < 0.05) and bleeding on probing (r(s) = -0.3, p < 0.001).

CONCLUSION

Mean salivary levels of granulocyte-macrophage colony-stimulating factor, interleukin-1beta, interleukin-2, interleukin-4, interleukin-5, interleukin-6, interleukin-8, interleukin-10, interferon-gamma and tumor necrosis factor-alpha could not discriminate between periodontal health and disease.

Effect of herbal, essential oil, and chlorhexidine mouthrinses on the composition of the subgingival microbiota and clinical periodontal parameters

OBJECTIVE

The purpose of the present investigation was to determine if antimicrobial mouthrinses with different formulations could affect the composition of the subgingival microbiota and clinical parameters of adjacent tissues in periodontal maintenance subjects.

METHODS

One-hundred and sixteen subjects, who had been treated for chronic periodontitis and were in a maintenance program, were randomly assigned one of four mouthrinses, to be used twice daily for three months. The mouthrinses were herbal 1, herbal 2, essential oil, and chlorhexidine. Clinical measurements and subgingival plaque samples were taken at baseline and at three months. Plaque samples were individually evaluated for 18 test species/taxa using checkerboard DNA-DNA hybridization. Significance of differences between baseline and three months for both microbiological and clinical parameters were determined using the Wilcoxon Signed Ranks test. Significance of difference among groups for change in clinical and microbiological parameters was determined using analysis of covariance (ANCOVA), adjusting for baseline values.

RESULTS

Shifts in species proportions differed significantly for 9/18 test species/taxa among the four mouthrinse groups. Streptococcus and Capnocytophaga species were reduced most in the herbal rinse groups, while Veillonella parvula was reduced most in the essential oil and chlorhexidine groups. Actinomyces were also markedly reduced in the chlorhexidine group. Mean Plaque (PI) and Gingival Indices (GI) were reduced between baseline and three months in each group. Results emphasize that chlorhexidine (p < 0.001) and herbal (p < 0.05) rinses significantly reduced PI. Some subjects in each group responded better than others.

CONCLUSION

All four mouthrinses tested produced shifts in the composition of subgingival microbiota, although the results differed among the groups. The observed microbial changes were accompanied by improvements in clinical parameters in the periodontal maintenance subjects.

Factors affecting human supragingival biofilm composition. II. Tooth position

BACKGROUND AND OBJECTIVE

Little is known regarding the factors that affect the microbial composition of supragingival biofilms. This study was designed to test the hypothesis that tooth location affects the microbial composition of supragingival plaque beyond the effect due to plaque mass as reflected by total DNA probe count.

MATERIAL AND METHODS

Supragingival plaque samples were taken from the mesiobuccal aspect of each tooth in 187 subjects (n = 4745 samples). All samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. Significance of differences in mean species counts and proportions were determined among tooth surfaces and six tooth type categories: molars, bicuspids, incisors/canines in the mandible and maxilla separately using the Kruskal-Wallis test. Stepwise multiple linear regression was employed to examine the relationship between species proportions and total DNA probe count, tooth location, periodontal and smoking status, age and sex.

RESULTS

All species differed significantly among tooth types and among the six tooth categories. Higher plaque levels were seen on molars and lower incisors. Some differences observed between tooth types could be partly explained by the level of plaque. Teeth with high plaque mass exhibited high levels of Capnocytophaga gingivalis, Actinomyces naeslundii genospecies 2, Campylobacter rectus and Campylobacter showae. However, certain species, such as Veillonella parvula and Streptococcus sanguinis, differed significantly at different tooth locations despite similarities in plaque mass. Twenty of the test species exhibited a significant association with tooth location after adjusting for total DNA probe count and subject level factors.

CONCLUSION

While plaque mass was associated with differences in proportions of many species in supragingival biofilms, tooth location also was strongly associated with species proportions in both univariate and multivariate analyses.

The reproducibility of curet sampling of subgingival biofilms

BACKGROUND

Because few studies have examined the critical issue of sampling reproducibility, the purpose of the present study was to examine the reproducibility of curet sampling of subgingival biofilms.

METHODS

Seven subgingival biofilm samples were taken successively, using a curet, from each of 80 sites and individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. One healthy site was sampled in each of 20 periodontally healthy subjects, and one sulcus/pocket of < or =3, 4 to 5, and > or =6 mm was sampled in each of 20 subjects with chronic periodontitis. The significance of differences in counts and proportions of individual species at the seven successive samplings for each probing depth (PD) category was determined using the Kruskal-Wallis test. The reproducibility of species proportions at each PD category was measured using the coefficient of variation (CV), and the consistency of microbial profiles across samples was examined using the minimum similarity coefficient.

RESULTS

There was no significant difference in the mean proportions of the 40 test species in the seven successive samples in each of the four PD categories. The median CV for individual species in the same site was 0.79 (95% confidence interval [CI]: 0.76 to 0.82) compared to 1.76 (95% CI: 1.69 to 1.82) in samples from different sites. The within-site mean minimum similarity coefficient (+/- SEM) was 51.2% +/- 2.2%, and it was 27.9% +/- 0.3% between sites.

CONCLUSION

The proportions of species remained consistent in successive curet samples, indicating that the use of curets provided a reliable and reproducible method to obtain subgingival samples.

Microbial complexes in supragingival plaque

BACKGROUND/AIMS

To examine microbial communities in supragingival biofilm samples.

METHODS

Supragingival plaque samples were taken from 187 subjects at baseline (n = 4745). Fifty-five subjects provided supragingival plaque samples at 1-7 days after professional tooth cleaning (n = 1456); 93 subjects provided 8044 samples between 3 and 24 months post-therapy. All samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. Microbial associations among species were sought using cluster analysis and community ordination techniques for the three groups separately.

RESULTS

Six complexes were formed for the baseline samples. Similar complexes were formed for the samples taken 3-24 months post-therapy. However, distinct changes were observed in microbial communities in samples taken during the 7 days of plaque redevelopment. The complexes related to clinical parameters of periodontal disease.

CONCLUSION

There were specific microbial complexes in supragingival plaque that were similar to those found in subgingival plaque samples with a few minor differences. The relation of previously unclustered taxa to the complexes was also described.

Clinical and Microbiologic Changes Associated With the Combined Use of a Powered Toothbrush and a Triclosan/Copolymer Dentifrice: A 3-Year Prospective Study

BACKGROUND

Different means are available for self-performed oral hygiene. The aim of this study was to evaluate the clinical and microbiologic effects of a preventive homecare program including the combined use of a powered toothbrush and a triclosan/copolymer-containing dentifrice.

METHODS

A total of 160 adult subjects without signs of destructive periodontal disease were recruited for this 3-year randomized controlled trial. The subjects were assigned to a homecare program using an oscillating/rotating powered toothbrush and a triclosan/copolymer/fluoride-containing dentifrice (test) or a manual toothbrush and a standard fluoride-containing dentifrice (control). Supragingival polishing and reinforcement of homecare procedures were provided every 6 months. Plaque, bleeding on probing (BOP), and probing depth (PD) were scored at baseline and after 1, 2, and 3 years. Subgingival plaque samples were taken from the mesial aspect of each tooth at baseline and after 1, 2, and 3 years and were analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. All data analyses were based on "intention-to-treat" with the subject as the statistical unit.

RESULTS

Compared to baseline, no significant changes in clinical parameters were observed during the 3 years, except for a reduction in the mean PD at the 2- and 3-year follow-up examinations (P <0.05). No significant differences were found between the two groups with regard to plaque, BOP, or PD or in the mean counts of the 40 species at any time point.

CONCLUSION

The study failed to prove additional benefits of the combined use of a powered toothbrush and a triclosan/copolymer-containing dentifrice in adult subjects without signs of destructive periodontal disease.

Use of multiple-displacement amplification and checkerboard DNA-DNA hybridization to examine the microbiota of endodontic infections

Multiple-displacement amplification (MDA) has been used to uniformly amplify bacterial genomes present in small samples, providing abundant targets for molecular analysis. The purpose of this investigation was to combine MDA and checkerboard DNA-DNA hybridization to examine the microbiota of endodontic infections. Sixty-six samples were collected from teeth with endodontic infections. Nonamplified and amplified samples were analyzed by checkerboard DNA-DNA hybridization for levels and proportions of 77 bacterial taxa. Counts, percentages of DNA probe counts, and percentages of teeth colonized for each species in amplified and nonamplified samples were computed. Significance of differences for each species between amplified and nonamplified samples was sought with Wilcoxon signed-rank test and adjusted for multiple comparisons. The amount of DNA in the samples ranged from 6.80 (+/- 5.2) ng before to 6.26 (+/- 1.73) mug after MDA. Seventy of the 77 DNA probes hybridized with one or more of the nonamplified samples. All probes hybridized with at least one sample after amplification. Most commonly detected species at levels of >10(4) in both amplified and nonamplified samples were Prevotella tannerae and Acinetobacter baumannii at frequencies between 89 and 100% of samples. The mean number of species at counts of >10(4) in amplified samples was 51.2 +/- 2.2 and in nonamplified samples was 14.5 +/- 1.7. The endodontic microbiota was far more complex than previously shown, although microbial profiles at teeth with or without periradicular lesions did not differ significantly. Species commonly detected in endodontic samples included P. tannerae, Prevotella oris, and A. baumannii.

Periodontal bacterial DNA suppresses the immune response to mutans streptococcal glucosyltransferase

Certain CpG motifs found in bacterial DNA enhance immune responses through Toll-like receptor 9 (TLR-9) and may also demonstrate adjuvant properties. Our objective was to determine if DNA from bacteria associated with periodontal disease could affect the immune response to other bacterial antigens in the oral cavity. Streptococcus sobrinus glucosyltransferase (GTF), an enzyme involved in dental caries pathogenesis, was used as a test antigen. Rowett rats were injected with aluminum hydroxide (alum) with buffer, alum-GTF, or alum-GTF together with either Escherichia coli DNA, Fusobacterium nucleatum DNA, or Porphyromonas gingivalis DNA. Contrary to expectation, animals receiving alum-GTF plus bacterial DNA (P. gingivalis in particular) demonstrated significantly reduced serum immunoglobulin G (IgG) antibody, salivary IgA antibody, and T-cell proliferation to GTF compared to animals immunized with alum-GTF alone. A diminished antibody response was also observed after administration of alum-GTF with the P. gingivalis DNA either together or separately, indicating that physical complexing of antigen and DNA was not responsible for the reduction in antibody. Since TLR triggering by DNA induces synthesis of prospective suppressive factors (e.g., suppressor of cytokine signaling [SOCS]), the effects of P. gingivalis DNA and GTF exposure on rat splenocyte production of SOCS family molecules and inflammatory cytokines were investigated in vitro. P. gingivalis DNA significantly up-regulated SOCS1 and SOCS5 expression and down-regulated interleukin-10 expression by cultured splenocytes. These results suggested that DNA from periodontal disease-associated bacteria did not enhance, but in fact suppressed, the immune response to a protein antigen from cariogenic streptococci, potentially through suppressive SOCS components triggered by innate mechanisms.

Multiple displacement amplification as an aid in checkerboard DNA-DNA hybridization

OBJECTIVE

The study aimed to determine if multiple displacement amplification could be used to provide abundant target DNA and DNA probes for checkerboard DNA-DNA hybridization.

METHODS

Multiple displacement amplification was used to amplify 1 and 10 ng DNA from 16 individual bacterial species, DNA from single colonies, from a mixture of 20 bacterial species and oral biofilm samples, such as supragingival plaque, subgingival plaque, buccal swab and root canal samples. Samples in reaction buffer were heat-denatured at 95 degrees C for 3 min and cooled to 4 degrees C. Phi29 DNA polymerase was added and the mixture was incubated at 30 degrees C for 16-18 h. The quantity of the product was evaluated by the Picogreen assay. The amplified material was labeled with digoxigenin. The probes were compared with probes obtained from unamplified DNA using checkerboard DNA-DNA hybridization. Both amplified DNA and unamplified DNA were used as targets on the membrane. Amplified oral biofilm samples were compared to unamplified samples using checkerboard DNA-DNA hybridization.

RESULTS

The DNA yield ranged from 4 to 11 microg. DNA-DNA hybridization showed that the amplified genome of each species used either as target or as probe provided signals equivalent to controls and that amplification of a mixture of species provided signals comparable to those provided by the unamplified source mixture. Amplified oral biofilm samples exhibited comparable proportions of bacterial DNA when compared to the original unamplified samples.

CONCLUSIONS

The multiple displacement amplification technique is a simple and reliable method to uniformly amplify DNA for use in checkerboard DNA-DNA hybridization. It is also a useful tool in the amplification of clinical samples.

A three-year prospective study of adult subjects with gingivitis II: microbiological parameters

AIM

To investigate whether the clinical benefits obtained with a periodontal prevention programme in subjects with periodontal health or minimal disease were accompanied by beneficial changes in the subgingival microbiota.

MATERIAL AND METHODS

One hundred and twenty-four subjects completed the study. Subjects were clinically and microbiologically monitored at baseline, 1, 2 and 3 years. Subgingival plaque samples were taken from the mesiobuccal aspect of every tooth and were analysed for the levels of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples=13,477). The mean counts of each of the 40 test species were calculated for each subject at each time point. Significance of differences over time was sought using the Friedman test. p values were adjusted for multiple comparisons.

RESULTS

All clinical parameters, at the microbiologically sampled sites, improved over time. The clinical changes were accompanied by statistically significant decreases in the mean counts of 35 of the 40 test species. Major reductions occurred by year 2 for Actinomyces, Capnocytophaga, Campylobacter, Fusobacterium and Prevotella species. At year 3, there was a modest re-growth of the majority of the species.

CONCLUSIONS

The clinical improvements obtained through preventive measures were accompanied by a shift to a more host-compatible subgingival microbiota.

Clinical changes following four different periodontal therapies for the treatment of chronic periodontitis: 1-year results

OBJECTIVE

To compare clinical changes occurring in chronic periodontitis subjects receiving SRP alone or with systemically administered azithromycin, metronidazole or a sub-antimicrobial dose of doxycycline.

MATERIAL AND METHODS

92 chronic periodontitis subjects were randomly assigned to receive SRP alone (N=23) or combined with 500 mg azithromycin per day for 3 days (N=25), 250 mg metronidazole tid for 14 days (N=24) or 20 mg doxycycline bid for 3 months (N=20). Gingival redness, bleeding on probing, suppuration, pocket depth and attachment level were measured at baseline and 3, 6 and 12 months post therapy. The significance of changes in clinical parameters within groups over time was sought using the Friedman test and among groups using ANCOVA or the Kruskal Wallis test.

RESULTS

All groups showed clinical improvements at 12 months, with subjects receiving adjunctive agents showing a somewhat better response. Sites with initial pocket depth > 6 mm showed significantly greater pocket depth reduction and greater attachment gain in subjects receiving metronidazole or azithromycin than subjects in the other groups. Some subjects showed attachment loss at 12 months in each group ranging from 15% to 39% of subjects in the SDD and SRP only groups respectively.

CONCLUSION

This study, demonstrated that periodontal therapy provides clinical benefits and that antibiotics provide a clinical benefit over SRP alone, particularly at initially deeper periodontal pockets.

A three-year prospective study of adult subjects with gingivitis. I: clinical periodontal parameters

AIM

The objective of this study was to monitor prospectively clinical parameters in subjects without signs of destructive periodontal disease who were involved in a primary prevention programme, and to determine the changes that occurred between yearly examinations over a 3-year period.

MATERIAL AND METHODS

One hundred and twenty-six subjects aged at least 20 years with a maximum of two tooth sites with probing pocket depth (PPD)>4 mm and no proximal sites with clinical attachment loss participated in the study. Primary prevention was provided at baseline of the study and then every 6 months. Plaque, bleeding on probing (BoP) and PPD were scored at baseline, 1, 2 and 3 years.

RESULTS

There were no significant changes in the plaque score over the 3 years. After year 1, the BoP score was significantly improved with 5.6%, while no further improvement in BoP was found at years 2 and 3. The mean PPD decreased from 2.3 to 2.1 mm over the 3 years (p<0.05).

CONCLUSION

Although some individuals exhibiting minor signs of periodontal pathology may have benefited from the primary prevention, the overall clinical improvement was limited for such subjects in the present 3-year study.

Association of Eubacterium nodatum and Treponema denticola with human periodontitis lesions

BACKGROUND

The purpose of the present investigation was to compare the levels, proportions and percentage of sites colonized by 40 bacterial species in subgingival plaque samples from periodontally healthy subjects and patients with chronic periodontitis to seek possible pathogens other than the consensus pathogens Porphyromonas gingivalis and Tannerella forsythia.

METHOD

Subgingival plaque samples were taken from the mesial aspect of each tooth in 635 subjects with chronic periodontitis and 189 periodontally healthy subjects. The samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples = 21,832). Mean counts, % DNA probe counts and percentage of sites colonized at >10(5) were determined for each species in each subject and then averaged in each clinical group. Significance of difference between groups was determined using the Mann-Whitney test. Association between combinations of species and periodontal status was examined by stepwise logistic regression analysis. Analyses were repeated using a subset of subjects from both clinical groups who had proportions of P. gingivalis plus T. forsythia less than the median (4.42%) found in periodontally healthy subjects. All analyses were adjusted for multiple comparisons.

RESULTS

For the 824 subjects the consensus pathogens P. gingivalis and T. forsythia as well as Eubacterium nodatum and Treponema denticola had significantly higher mean counts, proportions and percentage of sites colonized in samples from subjects with periodontitis than from periodontally healthy subjects. There were significantly more Capnocytophaga gingivalis, Streptococcus gordonii and Veillonella parvula in periodontally healthy subjects. E. nodatum, T. denticola, Streptococcus oralis, Streptococcus intermedius, Fusobacterium nucleatum ssp. vincentii all had higher counts and proportions in diseased than healthy subjects who had low proportions of P. gingivalis and T. forsythia. Logistic regression analysis indicated that the same species groups were associated with disease status after adjusting for the proportions of the other species.

CONCLUSIONS

This investigation confirmed the strong association of P. gingivalis and T. forsythia with chronic periodontitis and emphasized a strong association of E. nodatum and T. denticola with periodontitis whether in the presence or absence of high levels of the consensus pathogens. Other species, including S. oralis, Eikenella corrodens, S. intermedius and F. nucleatum ssp. vincentii, were associated with disease when P. gingivalis and T. forsythia were present in low proportions.

Effects of metronidazole plus amoxicillin as the only therapy on the microbiological and clinical parameters of untreated chronic periodontitis

AIM

To determine the effect of metronidazole plus amoxicillin (M+A) as the sole therapy, on the subgingival microbiota of chronic periodontitis.

MATERIAL AND METHODS

Twenty-two patients with untreated chronic periodontitis were randomly assigned to a group that received M+A for 7 days, or to a group receiving scaling and root planing (SRP) and two placebos. Clinical measurements including sites with plaque, bleeding on probing (BOP), probing depth (PD) and attachment level (AL) were made at baseline, 3, 6, 9 and 12 months. Subgingival plaque samples were taken from all teeth at baseline 3, 6, 9 and 12 months for the counts of 40 subgingival species using checkerboard DNA-DNA hybridization.

RESULTS

Mean PD was reduced from 2.80+/-0.45 at baseline to 1.95+/-0.05 at 12 months (P<0.001) and from 2.39+/-0.41 to 1.95+/-0.10 (P<0.001) in the M+A- and SRP-treated patients, respectively. Corresponding values for relative mean AL were 10.07+/-1.30-9.77+/-0.34 (P<0.001) and 9.94+/-0.28-9.77+/-0.26 (P<0.001). Percentage of sites exhibiting BOP were 40.6+/-18.3-14.0+/-1.4 (P<0.001), and 38.5+/-5.1-19.0+/-2.8 (P<0.001) in the M+A and SRP groups, respectively. Mean total DNA probe counts and counts of the majority of the 40 test species were significantly reduced over time in both groups, with no significant differences detected at any time point between groups. At 12 months many of the species were still present at significantly lowered levels compared with their baseline counts in both groups.

CONCLUSIONS

Changes in clinical and microbiological parameters were similar after receiving systemically administered M+A as the sole therapy or after receiving SRP only.

Initial subgingival colonization of 'pristine' pockets

The treatment of periodontitis/peri-implantitis involves the reduction/eradication of periopathogens. After therapy, beneficial and pathogenic species recolonize the subgingival area. The dynamics of recolonization and especially the role of the supragingival environment in this process are still not well-understood. This prospective, split-mouth study followed the early colonization of 'pristine' pockets created during implant surgery (16 partially edentulous patients), to record the time needed before a complex subgingival flora could be established with the supragingival area as the single source. Four subgingival plaque samples were taken from shallow and medium pockets around implants (test), and neighboring teeth (undisturbed microbiota as reference) 1, 2, and 4 wks after abutment connection. Checkerboard DNA-DNA hybridization and culture data revealed a complex microbiota (including several pathogenic species) in the pristine pockets within a wk, with a minimal increase in counts up to 4 wks. Analysis of these data demonstrated that, even with the supragingival environment as the single source for colonizing bacteria, a complex subgingival microbiota can develop within 1 wk.

Stress and the periodontal diseases: growth responses of periodontal bacteria to Escherichia coli stress-associated autoinducer and exogenous Fe

Psychological stress is known to increase the circulating levels of the catecholamine hormones noradrenaline and adrenaline, which have been shown to influence the growth of a large number of bacterial species by acting in a siderophore-like manner or by inducing the production of novel autoinducers of growth. As we have previously demonstrated that periodontal organisms display differing growth responses to noradrenaline and adrenaline, the aim of this study was to determine whether these growth effects were based upon either siderophore-like or autoinducer mechanisms. Initial inocula of 43 microbial organisms normally found within the subgingival biofilm were established under anaerobic conditions (35 degrees C). Each strain was re-inoculated into a serum-based minimal medium and growth was assessed by optical density (OD(600 nm)) with test and control cultures performed in triplicate. Test cultures were supplemented with either 50 mum ferric nitrate or a previously described Escherichia coli autoinducer of growth. Significant growth effects for supplementation with ferric nitrate (13 species responding positively) and E. coli autoinducer (24 species responding positively) were observed, with differences in growth response within bacterial species and within microbial complexes. When data for all organisms were compared with published responses to catecholamines there were only weak correlations with Fe (r = 0.28) and E. coli autoinducer (r = 0.34) responses. However, large positive responses (> 25% increase) to free Fe and/or E. coli autoinducer were significantly more prevalent in the group of organisms (n = 12) known to exhibit similar responses to catecholamine hormones (P < 0.01; chi2 = 4.56). The results support the view that catecholamines may exert their effects on subgingival organisms by initiating autoinducer production, or simply by acting in a siderophore-like manner, scavenging bound iron from the local environment. It is possible that autoinducer mechanisms may play an important role in the response of oral microorganisms to stress hormones, thereby contributing to the clinical course of stress-associated periodontal diseases.